Source file src/cmd/go/internal/load/pkg.go

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package load loads packages.
     6  package load
     7  
     8  import (
     9  	"bytes"
    10  	"cmd/internal/objabi"
    11  	"context"
    12  	"encoding/json"
    13  	"errors"
    14  	"fmt"
    15  	"go/build"
    16  	"go/scanner"
    17  	"go/token"
    18  	"internal/godebug"
    19  	"internal/platform"
    20  	"io/fs"
    21  	"os"
    22  	pathpkg "path"
    23  	"path/filepath"
    24  	"runtime"
    25  	"runtime/debug"
    26  	"slices"
    27  	"sort"
    28  	"strconv"
    29  	"strings"
    30  	"time"
    31  	"unicode"
    32  	"unicode/utf8"
    33  
    34  	"cmd/go/internal/base"
    35  	"cmd/go/internal/cfg"
    36  	"cmd/go/internal/fips140"
    37  	"cmd/go/internal/fsys"
    38  	"cmd/go/internal/gover"
    39  	"cmd/go/internal/imports"
    40  	"cmd/go/internal/modfetch"
    41  	"cmd/go/internal/modindex"
    42  	"cmd/go/internal/modinfo"
    43  	"cmd/go/internal/modload"
    44  	"cmd/go/internal/search"
    45  	"cmd/go/internal/str"
    46  	"cmd/go/internal/trace"
    47  	"cmd/go/internal/vcs"
    48  	"cmd/internal/par"
    49  	"cmd/internal/pathcache"
    50  	"cmd/internal/pkgpattern"
    51  
    52  	"golang.org/x/mod/modfile"
    53  	"golang.org/x/mod/module"
    54  )
    55  
    56  // A Package describes a single package found in a directory.
    57  type Package struct {
    58  	PackagePublic                 // visible in 'go list'
    59  	Internal      PackageInternal // for use inside go command only
    60  }
    61  
    62  type PackagePublic struct {
    63  	// Note: These fields are part of the go command's public API.
    64  	// See list.go. It is okay to add fields, but not to change or
    65  	// remove existing ones. Keep in sync with ../list/list.go
    66  	Dir           string                `json:",omitempty"` // directory containing package sources
    67  	ImportPath    string                `json:",omitempty"` // import path of package in dir
    68  	ImportComment string                `json:",omitempty"` // path in import comment on package statement
    69  	Name          string                `json:",omitempty"` // package name
    70  	Doc           string                `json:",omitempty"` // package documentation string
    71  	Target        string                `json:",omitempty"` // installed target for this package (may be executable)
    72  	Shlib         string                `json:",omitempty"` // the shared library that contains this package (only set when -linkshared)
    73  	Root          string                `json:",omitempty"` // Go root, Go path dir, or module root dir containing this package
    74  	ConflictDir   string                `json:",omitempty"` // Dir is hidden by this other directory
    75  	ForTest       string                `json:",omitempty"` // package is only for use in named test
    76  	Export        string                `json:",omitempty"` // file containing export data (set by go list -export)
    77  	BuildID       string                `json:",omitempty"` // build ID of the compiled package (set by go list -export)
    78  	Module        *modinfo.ModulePublic `json:",omitempty"` // info about package's module, if any
    79  	Match         []string              `json:",omitempty"` // command-line patterns matching this package
    80  	Goroot        bool                  `json:",omitempty"` // is this package found in the Go root?
    81  	Standard      bool                  `json:",omitempty"` // is this package part of the standard Go library?
    82  	DepOnly       bool                  `json:",omitempty"` // package is only as a dependency, not explicitly listed
    83  	BinaryOnly    bool                  `json:",omitempty"` // package cannot be recompiled
    84  	Incomplete    bool                  `json:",omitempty"` // was there an error loading this package or dependencies?
    85  
    86  	DefaultGODEBUG string `json:",omitempty"` // default GODEBUG setting (only for Name=="main")
    87  
    88  	// Stale and StaleReason remain here *only* for the list command.
    89  	// They are only initialized in preparation for list execution.
    90  	// The regular build determines staleness on the fly during action execution.
    91  	Stale       bool   `json:",omitempty"` // would 'go install' do anything for this package?
    92  	StaleReason string `json:",omitempty"` // why is Stale true?
    93  
    94  	// Source files
    95  	// If you add to this list you MUST add to p.AllFiles (below) too.
    96  	// Otherwise file name security lists will not apply to any new additions.
    97  	GoFiles           []string `json:",omitempty"` // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
    98  	CgoFiles          []string `json:",omitempty"` // .go source files that import "C"
    99  	CompiledGoFiles   []string `json:",omitempty"` // .go output from running cgo on CgoFiles
   100  	IgnoredGoFiles    []string `json:",omitempty"` // .go source files ignored due to build constraints
   101  	InvalidGoFiles    []string `json:",omitempty"` // .go source files with detected problems (parse error, wrong package name, and so on)
   102  	IgnoredOtherFiles []string `json:",omitempty"` // non-.go source files ignored due to build constraints
   103  	CFiles            []string `json:",omitempty"` // .c source files
   104  	CXXFiles          []string `json:",omitempty"` // .cc, .cpp and .cxx source files
   105  	MFiles            []string `json:",omitempty"` // .m source files
   106  	HFiles            []string `json:",omitempty"` // .h, .hh, .hpp and .hxx source files
   107  	FFiles            []string `json:",omitempty"` // .f, .F, .for and .f90 Fortran source files
   108  	SFiles            []string `json:",omitempty"` // .s source files
   109  	SwigFiles         []string `json:",omitempty"` // .swig files
   110  	SwigCXXFiles      []string `json:",omitempty"` // .swigcxx files
   111  	SysoFiles         []string `json:",omitempty"` // .syso system object files added to package
   112  
   113  	// Embedded files
   114  	EmbedPatterns []string `json:",omitempty"` // //go:embed patterns
   115  	EmbedFiles    []string `json:",omitempty"` // files matched by EmbedPatterns
   116  
   117  	// Cgo directives
   118  	CgoCFLAGS    []string `json:",omitempty"` // cgo: flags for C compiler
   119  	CgoCPPFLAGS  []string `json:",omitempty"` // cgo: flags for C preprocessor
   120  	CgoCXXFLAGS  []string `json:",omitempty"` // cgo: flags for C++ compiler
   121  	CgoFFLAGS    []string `json:",omitempty"` // cgo: flags for Fortran compiler
   122  	CgoLDFLAGS   []string `json:",omitempty"` // cgo: flags for linker
   123  	CgoPkgConfig []string `json:",omitempty"` // cgo: pkg-config names
   124  
   125  	// Dependency information
   126  	Imports   []string          `json:",omitempty"` // import paths used by this package
   127  	ImportMap map[string]string `json:",omitempty"` // map from source import to ImportPath (identity entries omitted)
   128  	Deps      []string          `json:",omitempty"` // all (recursively) imported dependencies
   129  
   130  	// Error information
   131  	// Incomplete is above, packed into the other bools
   132  	Error      *PackageError   `json:",omitempty"` // error loading this package (not dependencies)
   133  	DepsErrors []*PackageError `json:",omitempty"` // errors loading dependencies, collected by go list before output
   134  
   135  	// Test information
   136  	// If you add to this list you MUST add to p.AllFiles (below) too.
   137  	// Otherwise file name security lists will not apply to any new additions.
   138  	TestGoFiles        []string `json:",omitempty"` // _test.go files in package
   139  	TestImports        []string `json:",omitempty"` // imports from TestGoFiles
   140  	TestEmbedPatterns  []string `json:",omitempty"` // //go:embed patterns
   141  	TestEmbedFiles     []string `json:",omitempty"` // files matched by TestEmbedPatterns
   142  	XTestGoFiles       []string `json:",omitempty"` // _test.go files outside package
   143  	XTestImports       []string `json:",omitempty"` // imports from XTestGoFiles
   144  	XTestEmbedPatterns []string `json:",omitempty"` // //go:embed patterns
   145  	XTestEmbedFiles    []string `json:",omitempty"` // files matched by XTestEmbedPatterns
   146  }
   147  
   148  // AllFiles returns the names of all the files considered for the package.
   149  // This is used for sanity and security checks, so we include all files,
   150  // even IgnoredGoFiles, because some subcommands consider them.
   151  // The go/build package filtered others out (like foo_wrongGOARCH.s)
   152  // and that's OK.
   153  func (p *Package) AllFiles() []string {
   154  	files := str.StringList(
   155  		p.GoFiles,
   156  		p.CgoFiles,
   157  		// no p.CompiledGoFiles, because they are from GoFiles or generated by us
   158  		p.IgnoredGoFiles,
   159  		// no p.InvalidGoFiles, because they are from GoFiles
   160  		p.IgnoredOtherFiles,
   161  		p.CFiles,
   162  		p.CXXFiles,
   163  		p.MFiles,
   164  		p.HFiles,
   165  		p.FFiles,
   166  		p.SFiles,
   167  		p.SwigFiles,
   168  		p.SwigCXXFiles,
   169  		p.SysoFiles,
   170  		p.TestGoFiles,
   171  		p.XTestGoFiles,
   172  	)
   173  
   174  	// EmbedFiles may overlap with the other files.
   175  	// Dedup, but delay building the map as long as possible.
   176  	// Only files in the current directory (no slash in name)
   177  	// need to be checked against the files variable above.
   178  	var have map[string]bool
   179  	for _, file := range p.EmbedFiles {
   180  		if !strings.Contains(file, "/") {
   181  			if have == nil {
   182  				have = make(map[string]bool)
   183  				for _, file := range files {
   184  					have[file] = true
   185  				}
   186  			}
   187  			if have[file] {
   188  				continue
   189  			}
   190  		}
   191  		files = append(files, file)
   192  	}
   193  	return files
   194  }
   195  
   196  // Desc returns the package "description", for use in b.showOutput.
   197  func (p *Package) Desc() string {
   198  	if p.ForTest != "" {
   199  		return p.ImportPath + " [" + p.ForTest + ".test]"
   200  	}
   201  	if p.Internal.ForMain != "" {
   202  		return p.ImportPath + " [" + p.Internal.ForMain + "]"
   203  	}
   204  	return p.ImportPath
   205  }
   206  
   207  // IsTestOnly reports whether p is a test-only package.
   208  //
   209  // A “test-only” package is one that:
   210  //   - is a test-only variant of an ordinary package, or
   211  //   - is a synthesized "main" package for a test binary, or
   212  //   - contains only _test.go files.
   213  func (p *Package) IsTestOnly() bool {
   214  	return p.ForTest != "" ||
   215  		p.Internal.TestmainGo != nil ||
   216  		len(p.TestGoFiles)+len(p.XTestGoFiles) > 0 && len(p.GoFiles)+len(p.CgoFiles) == 0
   217  }
   218  
   219  type PackageInternal struct {
   220  	// Unexported fields are not part of the public API.
   221  	Build             *build.Package
   222  	Imports           []*Package          // this package's direct imports
   223  	CompiledImports   []string            // additional Imports necessary when using CompiledGoFiles (all from standard library); 1:1 with the end of PackagePublic.Imports
   224  	RawImports        []string            // this package's original imports as they appear in the text of the program; 1:1 with the end of PackagePublic.Imports
   225  	ForceLibrary      bool                // this package is a library (even if named "main")
   226  	CmdlineFiles      bool                // package built from files listed on command line
   227  	CmdlinePkg        bool                // package listed on command line
   228  	CmdlinePkgLiteral bool                // package listed as literal on command line (not via wildcard)
   229  	Local             bool                // imported via local path (./ or ../)
   230  	LocalPrefix       string              // interpret ./ and ../ imports relative to this prefix
   231  	ExeName           string              // desired name for temporary executable
   232  	FuzzInstrument    bool                // package should be instrumented for fuzzing
   233  	Cover             CoverSetup          // coverage mode and other setup info of -cover is being applied to this package
   234  	OmitDebug         bool                // tell linker not to write debug information
   235  	GobinSubdir       bool                // install target would be subdir of GOBIN
   236  	BuildInfo         *debug.BuildInfo    // add this info to package main
   237  	TestmainGo        *[]byte             // content for _testmain.go
   238  	Embed             map[string][]string // //go:embed comment mapping
   239  	OrigImportPath    string              // original import path before adding '_test' suffix
   240  	PGOProfile        string              // path to PGO profile
   241  	ForMain           string              // the main package if this package is built specifically for it
   242  
   243  	Asmflags   []string // -asmflags for this package
   244  	Gcflags    []string // -gcflags for this package
   245  	Ldflags    []string // -ldflags for this package
   246  	Gccgoflags []string // -gccgoflags for this package
   247  }
   248  
   249  // A NoGoError indicates that no Go files for the package were applicable to the
   250  // build for that package.
   251  //
   252  // That may be because there were no files whatsoever, or because all files were
   253  // excluded, or because all non-excluded files were test sources.
   254  type NoGoError struct {
   255  	Package *Package
   256  }
   257  
   258  func (e *NoGoError) Error() string {
   259  	if len(e.Package.IgnoredGoFiles) > 0 {
   260  		// Go files exist, but they were ignored due to build constraints.
   261  		return "build constraints exclude all Go files in " + e.Package.Dir
   262  	}
   263  	if len(e.Package.TestGoFiles)+len(e.Package.XTestGoFiles) > 0 {
   264  		// Test Go files exist, but we're not interested in them.
   265  		// The double-negative is unfortunate but we want e.Package.Dir
   266  		// to appear at the end of error message.
   267  		return "no non-test Go files in " + e.Package.Dir
   268  	}
   269  	return "no Go files in " + e.Package.Dir
   270  }
   271  
   272  // setLoadPackageDataError presents an error found when loading package data
   273  // as a *PackageError. It has special cases for some common errors to improve
   274  // messages shown to users and reduce redundancy.
   275  //
   276  // setLoadPackageDataError returns true if it's safe to load information about
   277  // imported packages, for example, if there was a parse error loading imports
   278  // in one file, but other files are okay.
   279  func (p *Package) setLoadPackageDataError(err error, path string, stk *ImportStack, importPos []token.Position) {
   280  	matchErr, isMatchErr := err.(*search.MatchError)
   281  	if isMatchErr && matchErr.Match.Pattern() == path {
   282  		if matchErr.Match.IsLiteral() {
   283  			// The error has a pattern has a pattern similar to the import path.
   284  			// It may be slightly different (./foo matching example.com/foo),
   285  			// but close enough to seem redundant.
   286  			// Unwrap the error so we don't show the pattern.
   287  			err = matchErr.Err
   288  		}
   289  	}
   290  
   291  	// Replace (possibly wrapped) *build.NoGoError with *load.NoGoError.
   292  	// The latter is more specific about the cause.
   293  	var nogoErr *build.NoGoError
   294  	if errors.As(err, &nogoErr) {
   295  		if p.Dir == "" && nogoErr.Dir != "" {
   296  			p.Dir = nogoErr.Dir
   297  		}
   298  		err = &NoGoError{Package: p}
   299  	}
   300  
   301  	// Take only the first error from a scanner.ErrorList. PackageError only
   302  	// has room for one position, so we report the first error with a position
   303  	// instead of all of the errors without a position.
   304  	var pos string
   305  	var isScanErr bool
   306  	if scanErr, ok := err.(scanner.ErrorList); ok && len(scanErr) > 0 {
   307  		isScanErr = true // For stack push/pop below.
   308  
   309  		scanPos := scanErr[0].Pos
   310  		scanPos.Filename = base.ShortPath(scanPos.Filename)
   311  		pos = scanPos.String()
   312  		err = errors.New(scanErr[0].Msg)
   313  	}
   314  
   315  	// Report the error on the importing package if the problem is with the import declaration
   316  	// for example, if the package doesn't exist or if the import path is malformed.
   317  	// On the other hand, don't include a position if the problem is with the imported package,
   318  	// for example there are no Go files (NoGoError), or there's a problem in the imported
   319  	// package's source files themselves (scanner errors).
   320  	//
   321  	// TODO(matloob): Perhaps make each of those the errors in the first group
   322  	// (including modload.ImportMissingError, ImportMissingSumError, and the
   323  	// corresponding "cannot find package %q in any of" GOPATH-mode error
   324  	// produced in build.(*Context).Import; modload.AmbiguousImportError,
   325  	// and modload.PackageNotInModuleError; and the malformed module path errors
   326  	// produced in golang.org/x/mod/module.CheckMod) implement an interface
   327  	// to make it easier to check for them? That would save us from having to
   328  	// move the modload errors into this package to avoid a package import cycle,
   329  	// and from having to export an error type for the errors produced in build.
   330  	if !isMatchErr && (nogoErr != nil || isScanErr) {
   331  		stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
   332  		defer stk.Pop()
   333  	}
   334  
   335  	p.Error = &PackageError{
   336  		ImportStack: stk.Copy(),
   337  		Pos:         pos,
   338  		Err:         err,
   339  	}
   340  	p.Incomplete = true
   341  
   342  	top, ok := stk.Top()
   343  	if ok && path != top.Pkg {
   344  		p.Error.setPos(importPos)
   345  	}
   346  }
   347  
   348  // Resolve returns the resolved version of imports,
   349  // which should be p.TestImports or p.XTestImports, NOT p.Imports.
   350  // The imports in p.TestImports and p.XTestImports are not recursively
   351  // loaded during the initial load of p, so they list the imports found in
   352  // the source file, but most processing should be over the vendor-resolved
   353  // import paths. We do this resolution lazily both to avoid file system work
   354  // and because the eventual real load of the test imports (during 'go test')
   355  // can produce better error messages if it starts with the original paths.
   356  // The initial load of p loads all the non-test imports and rewrites
   357  // the vendored paths, so nothing should ever call p.vendored(p.Imports).
   358  func (p *Package) Resolve(imports []string) []string {
   359  	if len(imports) > 0 && len(p.Imports) > 0 && &imports[0] == &p.Imports[0] {
   360  		panic("internal error: p.Resolve(p.Imports) called")
   361  	}
   362  	seen := make(map[string]bool)
   363  	var all []string
   364  	for _, path := range imports {
   365  		path = ResolveImportPath(p, path)
   366  		if !seen[path] {
   367  			seen[path] = true
   368  			all = append(all, path)
   369  		}
   370  	}
   371  	sort.Strings(all)
   372  	return all
   373  }
   374  
   375  // CoverSetup holds parameters related to coverage setup for a given package (covermode, etc).
   376  type CoverSetup struct {
   377  	Mode    string // coverage mode for this package
   378  	Cfg     string // path to config file to pass to "go tool cover"
   379  	GenMeta bool   // ask cover tool to emit a static meta data if set
   380  }
   381  
   382  func (p *Package) copyBuild(opts PackageOpts, pp *build.Package) {
   383  	p.Internal.Build = pp
   384  
   385  	if pp.PkgTargetRoot != "" && cfg.BuildPkgdir != "" {
   386  		old := pp.PkgTargetRoot
   387  		pp.PkgRoot = cfg.BuildPkgdir
   388  		pp.PkgTargetRoot = cfg.BuildPkgdir
   389  		if pp.PkgObj != "" {
   390  			pp.PkgObj = filepath.Join(cfg.BuildPkgdir, strings.TrimPrefix(pp.PkgObj, old))
   391  		}
   392  	}
   393  
   394  	p.Dir = pp.Dir
   395  	p.ImportPath = pp.ImportPath
   396  	p.ImportComment = pp.ImportComment
   397  	p.Name = pp.Name
   398  	p.Doc = pp.Doc
   399  	p.Root = pp.Root
   400  	p.ConflictDir = pp.ConflictDir
   401  	p.BinaryOnly = pp.BinaryOnly
   402  
   403  	// TODO? Target
   404  	p.Goroot = pp.Goroot || fips140.Snapshot() && str.HasFilePathPrefix(p.Dir, fips140.Dir())
   405  	p.Standard = p.Goroot && p.ImportPath != "" && search.IsStandardImportPath(p.ImportPath)
   406  	p.GoFiles = pp.GoFiles
   407  	p.CgoFiles = pp.CgoFiles
   408  	p.IgnoredGoFiles = pp.IgnoredGoFiles
   409  	p.InvalidGoFiles = pp.InvalidGoFiles
   410  	p.IgnoredOtherFiles = pp.IgnoredOtherFiles
   411  	p.CFiles = pp.CFiles
   412  	p.CXXFiles = pp.CXXFiles
   413  	p.MFiles = pp.MFiles
   414  	p.HFiles = pp.HFiles
   415  	p.FFiles = pp.FFiles
   416  	p.SFiles = pp.SFiles
   417  	p.SwigFiles = pp.SwigFiles
   418  	p.SwigCXXFiles = pp.SwigCXXFiles
   419  	p.SysoFiles = pp.SysoFiles
   420  	if cfg.BuildMSan {
   421  		// There's no way for .syso files to be built both with and without
   422  		// support for memory sanitizer. Assume they are built without,
   423  		// and drop them.
   424  		p.SysoFiles = nil
   425  	}
   426  	p.CgoCFLAGS = pp.CgoCFLAGS
   427  	p.CgoCPPFLAGS = pp.CgoCPPFLAGS
   428  	p.CgoCXXFLAGS = pp.CgoCXXFLAGS
   429  	p.CgoFFLAGS = pp.CgoFFLAGS
   430  	p.CgoLDFLAGS = pp.CgoLDFLAGS
   431  	p.CgoPkgConfig = pp.CgoPkgConfig
   432  	// We modify p.Imports in place, so make copy now.
   433  	p.Imports = make([]string, len(pp.Imports))
   434  	copy(p.Imports, pp.Imports)
   435  	p.Internal.RawImports = pp.Imports
   436  	p.TestGoFiles = pp.TestGoFiles
   437  	p.TestImports = pp.TestImports
   438  	p.XTestGoFiles = pp.XTestGoFiles
   439  	p.XTestImports = pp.XTestImports
   440  	if opts.IgnoreImports {
   441  		p.Imports = nil
   442  		p.Internal.RawImports = nil
   443  		p.TestImports = nil
   444  		p.XTestImports = nil
   445  	}
   446  	p.EmbedPatterns = pp.EmbedPatterns
   447  	p.TestEmbedPatterns = pp.TestEmbedPatterns
   448  	p.XTestEmbedPatterns = pp.XTestEmbedPatterns
   449  	p.Internal.OrigImportPath = pp.ImportPath
   450  }
   451  
   452  // A PackageError describes an error loading information about a package.
   453  type PackageError struct {
   454  	ImportStack      ImportStack // shortest path from package named on command line to this one with position
   455  	Pos              string      // position of error
   456  	Err              error       // the error itself
   457  	IsImportCycle    bool        // the error is an import cycle
   458  	alwaysPrintStack bool        // whether to always print the ImportStack
   459  }
   460  
   461  func (p *PackageError) Error() string {
   462  	// TODO(#43696): decide when to print the stack or the position based on
   463  	// the error type and whether the package is in the main module.
   464  	// Document the rationale.
   465  	if p.Pos != "" && (len(p.ImportStack) == 0 || !p.alwaysPrintStack) {
   466  		// Omit import stack. The full path to the file where the error
   467  		// is the most important thing.
   468  		return p.Pos + ": " + p.Err.Error()
   469  	}
   470  
   471  	// If the error is an ImportPathError, and the last path on the stack appears
   472  	// in the error message, omit that path from the stack to avoid repetition.
   473  	// If an ImportPathError wraps another ImportPathError that matches the
   474  	// last path on the stack, we don't omit the path. An error like
   475  	// "package A imports B: error loading C caused by B" would not be clearer
   476  	// if "imports B" were omitted.
   477  	if len(p.ImportStack) == 0 {
   478  		return p.Err.Error()
   479  	}
   480  	var optpos string
   481  	if p.Pos != "" {
   482  		optpos = "\n\t" + p.Pos
   483  	}
   484  	imports := p.ImportStack.Pkgs()
   485  	if p.IsImportCycle {
   486  		imports = p.ImportStack.PkgsWithPos()
   487  	}
   488  	return "package " + strings.Join(imports, "\n\timports ") + optpos + ": " + p.Err.Error()
   489  }
   490  
   491  func (p *PackageError) Unwrap() error { return p.Err }
   492  
   493  // PackageError implements MarshalJSON so that Err is marshaled as a string
   494  // and non-essential fields are omitted.
   495  func (p *PackageError) MarshalJSON() ([]byte, error) {
   496  	perr := struct {
   497  		ImportStack []string // use []string for package names
   498  		Pos         string
   499  		Err         string
   500  	}{p.ImportStack.Pkgs(), p.Pos, p.Err.Error()}
   501  	return json.Marshal(perr)
   502  }
   503  
   504  func (p *PackageError) setPos(posList []token.Position) {
   505  	if len(posList) == 0 {
   506  		return
   507  	}
   508  	pos := posList[0]
   509  	pos.Filename = base.ShortPath(pos.Filename)
   510  	p.Pos = pos.String()
   511  }
   512  
   513  // ImportPathError is a type of error that prevents a package from being loaded
   514  // for a given import path. When such a package is loaded, a *Package is
   515  // returned with Err wrapping an ImportPathError: the error is attached to
   516  // the imported package, not the importing package.
   517  //
   518  // The string returned by ImportPath must appear in the string returned by
   519  // Error. Errors that wrap ImportPathError (such as PackageError) may omit
   520  // the import path.
   521  type ImportPathError interface {
   522  	error
   523  	ImportPath() string
   524  }
   525  
   526  var (
   527  	_ ImportPathError = (*importError)(nil)
   528  	_ ImportPathError = (*mainPackageError)(nil)
   529  	_ ImportPathError = (*modload.ImportMissingError)(nil)
   530  	_ ImportPathError = (*modload.ImportMissingSumError)(nil)
   531  	_ ImportPathError = (*modload.DirectImportFromImplicitDependencyError)(nil)
   532  )
   533  
   534  type importError struct {
   535  	importPath string
   536  	err        error // created with fmt.Errorf
   537  }
   538  
   539  func ImportErrorf(path, format string, args ...any) ImportPathError {
   540  	err := &importError{importPath: path, err: fmt.Errorf(format, args...)}
   541  	if errStr := err.Error(); !strings.Contains(errStr, path) && !strings.Contains(errStr, strconv.Quote(path)) {
   542  		panic(fmt.Sprintf("path %q not in error %q", path, errStr))
   543  	}
   544  	return err
   545  }
   546  
   547  func (e *importError) Error() string {
   548  	return e.err.Error()
   549  }
   550  
   551  func (e *importError) Unwrap() error {
   552  	// Don't return e.err directly, since we're only wrapping an error if %w
   553  	// was passed to ImportErrorf.
   554  	return errors.Unwrap(e.err)
   555  }
   556  
   557  func (e *importError) ImportPath() string {
   558  	return e.importPath
   559  }
   560  
   561  type ImportInfo struct {
   562  	Pkg string
   563  	Pos *token.Position
   564  }
   565  
   566  // An ImportStack is a stack of import paths, possibly with the suffix " (test)" appended.
   567  // The import path of a test package is the import path of the corresponding
   568  // non-test package with the suffix "_test" added.
   569  type ImportStack []ImportInfo
   570  
   571  func NewImportInfo(pkg string, pos *token.Position) ImportInfo {
   572  	return ImportInfo{Pkg: pkg, Pos: pos}
   573  }
   574  
   575  func (s *ImportStack) Push(p ImportInfo) {
   576  	*s = append(*s, p)
   577  }
   578  
   579  func (s *ImportStack) Pop() {
   580  	*s = (*s)[0 : len(*s)-1]
   581  }
   582  
   583  func (s *ImportStack) Copy() ImportStack {
   584  	return slices.Clone(*s)
   585  }
   586  
   587  func (s *ImportStack) Pkgs() []string {
   588  	ss := make([]string, 0, len(*s))
   589  	for _, v := range *s {
   590  		ss = append(ss, v.Pkg)
   591  	}
   592  	return ss
   593  }
   594  
   595  func (s *ImportStack) PkgsWithPos() []string {
   596  	ss := make([]string, 0, len(*s))
   597  	for _, v := range *s {
   598  		if v.Pos != nil {
   599  			ss = append(ss, v.Pkg+" from "+filepath.Base(v.Pos.Filename))
   600  		} else {
   601  			ss = append(ss, v.Pkg)
   602  		}
   603  	}
   604  	return ss
   605  }
   606  
   607  func (s *ImportStack) Top() (ImportInfo, bool) {
   608  	if len(*s) == 0 {
   609  		return ImportInfo{}, false
   610  	}
   611  	return (*s)[len(*s)-1], true
   612  }
   613  
   614  // shorterThan reports whether sp is shorter than t.
   615  // We use this to record the shortest import sequence
   616  // that leads to a particular package.
   617  func (sp *ImportStack) shorterThan(t []string) bool {
   618  	s := *sp
   619  	if len(s) != len(t) {
   620  		return len(s) < len(t)
   621  	}
   622  	// If they are the same length, settle ties using string ordering.
   623  	for i := range s {
   624  		siPkg := s[i].Pkg
   625  		if siPkg != t[i] {
   626  			return siPkg < t[i]
   627  		}
   628  	}
   629  	return false // they are equal
   630  }
   631  
   632  // packageCache is a lookup cache for LoadImport,
   633  // so that if we look up a package multiple times
   634  // we return the same pointer each time.
   635  var packageCache = map[string]*Package{}
   636  
   637  // dirToImportPath returns the pseudo-import path we use for a package
   638  // outside the Go path. It begins with _/ and then contains the full path
   639  // to the directory. If the package lives in c:\home\gopher\my\pkg then
   640  // the pseudo-import path is _/c_/home/gopher/my/pkg.
   641  // Using a pseudo-import path like this makes the ./ imports no longer
   642  // a special case, so that all the code to deal with ordinary imports works
   643  // automatically.
   644  func dirToImportPath(dir string) string {
   645  	return pathpkg.Join("_", strings.Map(makeImportValid, filepath.ToSlash(dir)))
   646  }
   647  
   648  func makeImportValid(r rune) rune {
   649  	// Should match Go spec, compilers, and ../../go/parser/parser.go:/isValidImport.
   650  	const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
   651  	if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
   652  		return '_'
   653  	}
   654  	return r
   655  }
   656  
   657  // Mode flags for loadImport and download (in get.go).
   658  const (
   659  	// ResolveImport means that loadImport should do import path expansion.
   660  	// That is, ResolveImport means that the import path came from
   661  	// a source file and has not been expanded yet to account for
   662  	// vendoring or possible module adjustment.
   663  	// Every import path should be loaded initially with ResolveImport,
   664  	// and then the expanded version (for example with the /vendor/ in it)
   665  	// gets recorded as the canonical import path. At that point, future loads
   666  	// of that package must not pass ResolveImport, because
   667  	// disallowVendor will reject direct use of paths containing /vendor/.
   668  	ResolveImport = 1 << iota
   669  
   670  	// ResolveModule is for download (part of "go get") and indicates
   671  	// that the module adjustment should be done, but not vendor adjustment.
   672  	ResolveModule
   673  
   674  	// GetTestDeps is for download (part of "go get") and indicates
   675  	// that test dependencies should be fetched too.
   676  	GetTestDeps
   677  
   678  	// The remainder are internal modes for calls to loadImport.
   679  
   680  	// cmdlinePkg is for a package mentioned on the command line.
   681  	cmdlinePkg
   682  
   683  	// cmdlinePkgLiteral is for a package mentioned on the command line
   684  	// without using any wildcards or meta-patterns.
   685  	cmdlinePkgLiteral
   686  )
   687  
   688  // LoadPackage does Load import, but without a parent package load context
   689  func LoadPackage(ctx context.Context, opts PackageOpts, path, srcDir string, stk *ImportStack, importPos []token.Position, mode int) *Package {
   690  	p, err := loadImport(ctx, opts, nil, path, srcDir, nil, stk, importPos, mode)
   691  	if err != nil {
   692  		base.Fatalf("internal error: loadImport of %q with nil parent returned an error", path)
   693  	}
   694  	return p
   695  }
   696  
   697  // loadImport scans the directory named by path, which must be an import path,
   698  // but possibly a local import path (an absolute file system path or one beginning
   699  // with ./ or ../). A local relative path is interpreted relative to srcDir.
   700  // It returns a *Package describing the package found in that directory.
   701  // loadImport does not set tool flags and should only be used by
   702  // this package, as part of a bigger load operation.
   703  // The returned PackageError, if any, describes why parent is not allowed
   704  // to import the named package, with the error referring to importPos.
   705  // The PackageError can only be non-nil when parent is not nil.
   706  func loadImport(ctx context.Context, opts PackageOpts, pre *preload, path, srcDir string, parent *Package, stk *ImportStack, importPos []token.Position, mode int) (*Package, *PackageError) {
   707  	ctx, span := trace.StartSpan(ctx, "modload.loadImport "+path)
   708  	defer span.Done()
   709  
   710  	if path == "" {
   711  		panic("LoadImport called with empty package path")
   712  	}
   713  
   714  	var parentPath, parentRoot string
   715  	parentIsStd := false
   716  	if parent != nil {
   717  		parentPath = parent.ImportPath
   718  		parentRoot = parent.Root
   719  		parentIsStd = parent.Standard
   720  	}
   721  	bp, loaded, err := loadPackageData(ctx, path, parentPath, srcDir, parentRoot, parentIsStd, mode)
   722  	if loaded && pre != nil && !opts.IgnoreImports {
   723  		pre.preloadImports(ctx, opts, bp.Imports, bp)
   724  	}
   725  	if bp == nil {
   726  		p := &Package{
   727  			PackagePublic: PackagePublic{
   728  				ImportPath: path,
   729  				Incomplete: true,
   730  			},
   731  		}
   732  		if importErr, ok := err.(ImportPathError); !ok || importErr.ImportPath() != path {
   733  			// Only add path to the error's import stack if it's not already present
   734  			// in the error.
   735  			//
   736  			// TODO(bcmills): setLoadPackageDataError itself has a similar Push / Pop
   737  			// sequence that empirically doesn't trigger for these errors, guarded by
   738  			// a somewhat complex condition. Figure out how to generalize that
   739  			// condition and eliminate the explicit calls here.
   740  			stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
   741  			defer stk.Pop()
   742  		}
   743  		p.setLoadPackageDataError(err, path, stk, nil)
   744  		return p, nil
   745  	}
   746  
   747  	setCmdline := func(p *Package) {
   748  		if mode&cmdlinePkg != 0 {
   749  			p.Internal.CmdlinePkg = true
   750  		}
   751  		if mode&cmdlinePkgLiteral != 0 {
   752  			p.Internal.CmdlinePkgLiteral = true
   753  		}
   754  	}
   755  
   756  	importPath := bp.ImportPath
   757  	p := packageCache[importPath]
   758  	if p != nil {
   759  		stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
   760  		p = reusePackage(p, stk)
   761  		stk.Pop()
   762  		setCmdline(p)
   763  	} else {
   764  		p = new(Package)
   765  		p.Internal.Local = build.IsLocalImport(path)
   766  		p.ImportPath = importPath
   767  		packageCache[importPath] = p
   768  
   769  		setCmdline(p)
   770  
   771  		// Load package.
   772  		// loadPackageData may return bp != nil even if an error occurs,
   773  		// in order to return partial information.
   774  		p.load(ctx, opts, path, stk, importPos, bp, err)
   775  
   776  		if !cfg.ModulesEnabled && path != cleanImport(path) {
   777  			p.Error = &PackageError{
   778  				ImportStack: stk.Copy(),
   779  				Err:         ImportErrorf(path, "non-canonical import path %q: should be %q", path, pathpkg.Clean(path)),
   780  			}
   781  			p.Incomplete = true
   782  			p.Error.setPos(importPos)
   783  		}
   784  	}
   785  
   786  	// Checked on every import because the rules depend on the code doing the importing.
   787  	if perr := disallowInternal(ctx, srcDir, parent, parentPath, p, stk); perr != nil {
   788  		perr.setPos(importPos)
   789  		return p, perr
   790  	}
   791  	if mode&ResolveImport != 0 {
   792  		if perr := disallowVendor(srcDir, path, parentPath, p, stk); perr != nil {
   793  			perr.setPos(importPos)
   794  			return p, perr
   795  		}
   796  	}
   797  
   798  	if p.Name == "main" && parent != nil && parent.Dir != p.Dir {
   799  		perr := &PackageError{
   800  			ImportStack: stk.Copy(),
   801  			Err:         ImportErrorf(path, "import %q is a program, not an importable package", path),
   802  		}
   803  		perr.setPos(importPos)
   804  		return p, perr
   805  	}
   806  
   807  	if p.Internal.Local && parent != nil && !parent.Internal.Local {
   808  		var err error
   809  		if path == "." {
   810  			err = ImportErrorf(path, "%s: cannot import current directory", path)
   811  		} else {
   812  			err = ImportErrorf(path, "local import %q in non-local package", path)
   813  		}
   814  		perr := &PackageError{
   815  			ImportStack: stk.Copy(),
   816  			Err:         err,
   817  		}
   818  		perr.setPos(importPos)
   819  		return p, perr
   820  	}
   821  
   822  	return p, nil
   823  }
   824  
   825  func extractFirstImport(importPos []token.Position) *token.Position {
   826  	if len(importPos) == 0 {
   827  		return nil
   828  	}
   829  	return &importPos[0]
   830  }
   831  
   832  // loadPackageData loads information needed to construct a *Package. The result
   833  // is cached, and later calls to loadPackageData for the same package will return
   834  // the same data.
   835  //
   836  // loadPackageData returns a non-nil package even if err is non-nil unless
   837  // the package path is malformed (for example, the path contains "mod/" or "@").
   838  //
   839  // loadPackageData returns a boolean, loaded, which is true if this is the
   840  // first time the package was loaded. Callers may preload imports in this case.
   841  func loadPackageData(ctx context.Context, path, parentPath, parentDir, parentRoot string, parentIsStd bool, mode int) (bp *build.Package, loaded bool, err error) {
   842  	ctx, span := trace.StartSpan(ctx, "load.loadPackageData "+path)
   843  	defer span.Done()
   844  
   845  	if path == "" {
   846  		panic("loadPackageData called with empty package path")
   847  	}
   848  
   849  	if strings.HasPrefix(path, "mod/") {
   850  		// Paths beginning with "mod/" might accidentally
   851  		// look in the module cache directory tree in $GOPATH/pkg/mod/.
   852  		// This prefix is owned by the Go core for possible use in the
   853  		// standard library (since it does not begin with a domain name),
   854  		// so it's OK to disallow entirely.
   855  		return nil, false, fmt.Errorf("disallowed import path %q", path)
   856  	}
   857  
   858  	if strings.Contains(path, "@") {
   859  		return nil, false, errors.New("can only use path@version syntax with 'go get' and 'go install' in module-aware mode")
   860  	}
   861  
   862  	// Determine canonical package path and directory.
   863  	// For a local import the identifier is the pseudo-import path
   864  	// we create from the full directory to the package.
   865  	// Otherwise it is the usual import path.
   866  	// For vendored imports, it is the expanded form.
   867  	//
   868  	// Note that when modules are enabled, local import paths are normally
   869  	// canonicalized by modload.LoadPackages before now. However, if there's an
   870  	// error resolving a local path, it will be returned untransformed
   871  	// so that 'go list -e' reports something useful.
   872  	importKey := importSpec{
   873  		path:        path,
   874  		parentPath:  parentPath,
   875  		parentDir:   parentDir,
   876  		parentRoot:  parentRoot,
   877  		parentIsStd: parentIsStd,
   878  		mode:        mode,
   879  	}
   880  	r := resolvedImportCache.Do(importKey, func() resolvedImport {
   881  		var r resolvedImport
   882  		if newPath, dir, ok := fips140.ResolveImport(path); ok {
   883  			r.path = newPath
   884  			r.dir = dir
   885  		} else if cfg.ModulesEnabled {
   886  			r.dir, r.path, r.err = modload.Lookup(parentPath, parentIsStd, path)
   887  		} else if build.IsLocalImport(path) {
   888  			r.dir = filepath.Join(parentDir, path)
   889  			r.path = dirToImportPath(r.dir)
   890  		} else if mode&ResolveImport != 0 {
   891  			// We do our own path resolution, because we want to
   892  			// find out the key to use in packageCache without the
   893  			// overhead of repeated calls to buildContext.Import.
   894  			// The code is also needed in a few other places anyway.
   895  			r.path = resolveImportPath(path, parentPath, parentDir, parentRoot, parentIsStd)
   896  		} else if mode&ResolveModule != 0 {
   897  			r.path = moduleImportPath(path, parentPath, parentDir, parentRoot)
   898  		}
   899  		if r.path == "" {
   900  			r.path = path
   901  		}
   902  		return r
   903  	})
   904  	// Invariant: r.path is set to the resolved import path. If the path cannot
   905  	// be resolved, r.path is set to path, the source import path.
   906  	// r.path is never empty.
   907  
   908  	// Load the package from its directory. If we already found the package's
   909  	// directory when resolving its import path, use that.
   910  	p, err := packageDataCache.Do(r.path, func() (*build.Package, error) {
   911  		loaded = true
   912  		var data struct {
   913  			p   *build.Package
   914  			err error
   915  		}
   916  		if r.dir != "" {
   917  			var buildMode build.ImportMode
   918  			buildContext := cfg.BuildContext
   919  			if !cfg.ModulesEnabled {
   920  				buildMode = build.ImportComment
   921  			} else {
   922  				buildContext.GOPATH = "" // Clear GOPATH so packages are imported as pure module packages
   923  			}
   924  			modroot := modload.PackageModRoot(ctx, r.path)
   925  			if modroot == "" && str.HasPathPrefix(r.dir, cfg.GOROOTsrc) {
   926  				modroot = cfg.GOROOTsrc
   927  				gorootSrcCmd := filepath.Join(cfg.GOROOTsrc, "cmd")
   928  				if str.HasPathPrefix(r.dir, gorootSrcCmd) {
   929  					modroot = gorootSrcCmd
   930  				}
   931  			}
   932  			if modroot != "" {
   933  				if rp, err := modindex.GetPackage(modroot, r.dir); err == nil {
   934  					data.p, data.err = rp.Import(cfg.BuildContext, buildMode)
   935  					goto Happy
   936  				} else if !errors.Is(err, modindex.ErrNotIndexed) {
   937  					base.Fatal(err)
   938  				}
   939  			}
   940  			data.p, data.err = buildContext.ImportDir(r.dir, buildMode)
   941  		Happy:
   942  			if cfg.ModulesEnabled {
   943  				// Override data.p.Root, since ImportDir sets it to $GOPATH, if
   944  				// the module is inside $GOPATH/src.
   945  				if info := modload.PackageModuleInfo(ctx, path); info != nil {
   946  					data.p.Root = info.Dir
   947  				}
   948  			}
   949  			if r.err != nil {
   950  				if data.err != nil {
   951  					// ImportDir gave us one error, and the module loader gave us another.
   952  					// We arbitrarily choose to keep the error from ImportDir because
   953  					// that's what our tests already expect, and it seems to provide a bit
   954  					// more detail in most cases.
   955  				} else if errors.Is(r.err, imports.ErrNoGo) {
   956  					// ImportDir said there were files in the package, but the module
   957  					// loader said there weren't. Which one is right?
   958  					// Without this special-case hack, the TestScript/test_vet case fails
   959  					// on the vetfail/p1 package (added in CL 83955).
   960  					// Apparently, imports.ShouldBuild biases toward rejecting files
   961  					// with invalid build constraints, whereas ImportDir biases toward
   962  					// accepting them.
   963  					//
   964  					// TODO(#41410: Figure out how this actually ought to work and fix
   965  					// this mess).
   966  				} else {
   967  					data.err = r.err
   968  				}
   969  			}
   970  		} else if r.err != nil {
   971  			data.p = new(build.Package)
   972  			data.err = r.err
   973  		} else if cfg.ModulesEnabled && path != "unsafe" {
   974  			data.p = new(build.Package)
   975  			data.err = fmt.Errorf("unknown import path %q: internal error: module loader did not resolve import", r.path)
   976  		} else {
   977  			buildMode := build.ImportComment
   978  			if mode&ResolveImport == 0 || r.path != path {
   979  				// Not vendoring, or we already found the vendored path.
   980  				buildMode |= build.IgnoreVendor
   981  			}
   982  			data.p, data.err = cfg.BuildContext.Import(r.path, parentDir, buildMode)
   983  		}
   984  		data.p.ImportPath = r.path
   985  
   986  		// Set data.p.BinDir in cases where go/build.Context.Import
   987  		// may give us a path we don't want.
   988  		if !data.p.Goroot {
   989  			if cfg.GOBIN != "" {
   990  				data.p.BinDir = cfg.GOBIN
   991  			} else if cfg.ModulesEnabled {
   992  				data.p.BinDir = modload.BinDir()
   993  			}
   994  		}
   995  
   996  		if !cfg.ModulesEnabled && data.err == nil &&
   997  			data.p.ImportComment != "" && data.p.ImportComment != path &&
   998  			!strings.Contains(path, "/vendor/") && !strings.HasPrefix(path, "vendor/") {
   999  			data.err = fmt.Errorf("code in directory %s expects import %q", data.p.Dir, data.p.ImportComment)
  1000  		}
  1001  		return data.p, data.err
  1002  	})
  1003  
  1004  	return p, loaded, err
  1005  }
  1006  
  1007  // importSpec describes an import declaration in source code. It is used as a
  1008  // cache key for resolvedImportCache.
  1009  type importSpec struct {
  1010  	path                              string
  1011  	parentPath, parentDir, parentRoot string
  1012  	parentIsStd                       bool
  1013  	mode                              int
  1014  }
  1015  
  1016  // resolvedImport holds a canonical identifier for a package. It may also contain
  1017  // a path to the package's directory and an error if one occurred. resolvedImport
  1018  // is the value type in resolvedImportCache.
  1019  type resolvedImport struct {
  1020  	path, dir string
  1021  	err       error
  1022  }
  1023  
  1024  // resolvedImportCache maps import strings to canonical package names.
  1025  var resolvedImportCache par.Cache[importSpec, resolvedImport]
  1026  
  1027  // packageDataCache maps canonical package names (string) to package metadata.
  1028  var packageDataCache par.ErrCache[string, *build.Package]
  1029  
  1030  // preloadWorkerCount is the number of concurrent goroutines that can load
  1031  // packages. Experimentally, there are diminishing returns with more than
  1032  // 4 workers. This was measured on the following machines.
  1033  //
  1034  // * MacBookPro with a 4-core Intel Core i7 CPU
  1035  // * Linux workstation with 6-core Intel Xeon CPU
  1036  // * Linux workstation with 24-core Intel Xeon CPU
  1037  //
  1038  // It is very likely (though not confirmed) that this workload is limited
  1039  // by memory bandwidth. We don't have a good way to determine the number of
  1040  // workers that would saturate the bus though, so runtime.GOMAXPROCS
  1041  // seems like a reasonable default.
  1042  var preloadWorkerCount = runtime.GOMAXPROCS(0)
  1043  
  1044  // preload holds state for managing concurrent preloading of package data.
  1045  //
  1046  // A preload should be created with newPreload before loading a large
  1047  // package graph. flush must be called when package loading is complete
  1048  // to ensure preload goroutines are no longer active. This is necessary
  1049  // because of global mutable state that cannot safely be read and written
  1050  // concurrently. In particular, packageDataCache may be cleared by "go get"
  1051  // in GOPATH mode, and modload.loaded (accessed via modload.Lookup) may be
  1052  // modified by modload.LoadPackages.
  1053  type preload struct {
  1054  	cancel chan struct{}
  1055  	sema   chan struct{}
  1056  }
  1057  
  1058  // newPreload creates a new preloader. flush must be called later to avoid
  1059  // accessing global state while it is being modified.
  1060  func newPreload() *preload {
  1061  	pre := &preload{
  1062  		cancel: make(chan struct{}),
  1063  		sema:   make(chan struct{}, preloadWorkerCount),
  1064  	}
  1065  	return pre
  1066  }
  1067  
  1068  // preloadMatches loads data for package paths matched by patterns.
  1069  // When preloadMatches returns, some packages may not be loaded yet, but
  1070  // loadPackageData and loadImport are always safe to call.
  1071  func (pre *preload) preloadMatches(ctx context.Context, opts PackageOpts, matches []*search.Match) {
  1072  	for _, m := range matches {
  1073  		for _, pkg := range m.Pkgs {
  1074  			select {
  1075  			case <-pre.cancel:
  1076  				return
  1077  			case pre.sema <- struct{}{}:
  1078  				go func(pkg string) {
  1079  					mode := 0 // don't use vendoring or module import resolution
  1080  					bp, loaded, err := loadPackageData(ctx, pkg, "", base.Cwd(), "", false, mode)
  1081  					<-pre.sema
  1082  					if bp != nil && loaded && err == nil && !opts.IgnoreImports {
  1083  						pre.preloadImports(ctx, opts, bp.Imports, bp)
  1084  					}
  1085  				}(pkg)
  1086  			}
  1087  		}
  1088  	}
  1089  }
  1090  
  1091  // preloadImports queues a list of imports for preloading.
  1092  // When preloadImports returns, some packages may not be loaded yet,
  1093  // but loadPackageData and loadImport are always safe to call.
  1094  func (pre *preload) preloadImports(ctx context.Context, opts PackageOpts, imports []string, parent *build.Package) {
  1095  	parentIsStd := parent.Goroot && parent.ImportPath != "" && search.IsStandardImportPath(parent.ImportPath)
  1096  	for _, path := range imports {
  1097  		if path == "C" || path == "unsafe" {
  1098  			continue
  1099  		}
  1100  		select {
  1101  		case <-pre.cancel:
  1102  			return
  1103  		case pre.sema <- struct{}{}:
  1104  			go func(path string) {
  1105  				bp, loaded, err := loadPackageData(ctx, path, parent.ImportPath, parent.Dir, parent.Root, parentIsStd, ResolveImport)
  1106  				<-pre.sema
  1107  				if bp != nil && loaded && err == nil && !opts.IgnoreImports {
  1108  					pre.preloadImports(ctx, opts, bp.Imports, bp)
  1109  				}
  1110  			}(path)
  1111  		}
  1112  	}
  1113  }
  1114  
  1115  // flush stops pending preload operations. flush blocks until preload calls to
  1116  // loadPackageData have completed. The preloader will not make any new calls
  1117  // to loadPackageData.
  1118  func (pre *preload) flush() {
  1119  	// flush is usually deferred.
  1120  	// Don't hang program waiting for workers on panic.
  1121  	if v := recover(); v != nil {
  1122  		panic(v)
  1123  	}
  1124  
  1125  	close(pre.cancel)
  1126  	for i := 0; i < preloadWorkerCount; i++ {
  1127  		pre.sema <- struct{}{}
  1128  	}
  1129  }
  1130  
  1131  func cleanImport(path string) string {
  1132  	orig := path
  1133  	path = pathpkg.Clean(path)
  1134  	if strings.HasPrefix(orig, "./") && path != ".." && !strings.HasPrefix(path, "../") {
  1135  		path = "./" + path
  1136  	}
  1137  	return path
  1138  }
  1139  
  1140  var isDirCache par.Cache[string, bool]
  1141  
  1142  func isDir(path string) bool {
  1143  	return isDirCache.Do(path, func() bool {
  1144  		fi, err := fsys.Stat(path)
  1145  		return err == nil && fi.IsDir()
  1146  	})
  1147  }
  1148  
  1149  // ResolveImportPath returns the true meaning of path when it appears in parent.
  1150  // There are two different resolutions applied.
  1151  // First, there is Go 1.5 vendoring (golang.org/s/go15vendor).
  1152  // If vendor expansion doesn't trigger, then the path is also subject to
  1153  // Go 1.11 module legacy conversion (golang.org/issue/25069).
  1154  func ResolveImportPath(parent *Package, path string) (found string) {
  1155  	var parentPath, parentDir, parentRoot string
  1156  	parentIsStd := false
  1157  	if parent != nil {
  1158  		parentPath = parent.ImportPath
  1159  		parentDir = parent.Dir
  1160  		parentRoot = parent.Root
  1161  		parentIsStd = parent.Standard
  1162  	}
  1163  	return resolveImportPath(path, parentPath, parentDir, parentRoot, parentIsStd)
  1164  }
  1165  
  1166  func resolveImportPath(path, parentPath, parentDir, parentRoot string, parentIsStd bool) (found string) {
  1167  	if cfg.ModulesEnabled {
  1168  		if _, p, e := modload.Lookup(parentPath, parentIsStd, path); e == nil {
  1169  			return p
  1170  		}
  1171  		return path
  1172  	}
  1173  	found = vendoredImportPath(path, parentPath, parentDir, parentRoot)
  1174  	if found != path {
  1175  		return found
  1176  	}
  1177  	return moduleImportPath(path, parentPath, parentDir, parentRoot)
  1178  }
  1179  
  1180  // dirAndRoot returns the source directory and workspace root
  1181  // for the package p, guaranteeing that root is a path prefix of dir.
  1182  func dirAndRoot(path string, dir, root string) (string, string) {
  1183  	origDir, origRoot := dir, root
  1184  	dir = filepath.Clean(dir)
  1185  	root = filepath.Join(root, "src")
  1186  	if !str.HasFilePathPrefix(dir, root) || path != "command-line-arguments" && filepath.Join(root, path) != dir {
  1187  		// Look for symlinks before reporting error.
  1188  		dir = expandPath(dir)
  1189  		root = expandPath(root)
  1190  	}
  1191  
  1192  	if !str.HasFilePathPrefix(dir, root) || len(dir) <= len(root) || dir[len(root)] != filepath.Separator || path != "command-line-arguments" && !build.IsLocalImport(path) && filepath.Join(root, path) != dir {
  1193  		debug.PrintStack()
  1194  		base.Fatalf("unexpected directory layout:\n"+
  1195  			"	import path: %s\n"+
  1196  			"	root: %s\n"+
  1197  			"	dir: %s\n"+
  1198  			"	expand root: %s\n"+
  1199  			"	expand dir: %s\n"+
  1200  			"	separator: %s",
  1201  			path,
  1202  			filepath.Join(origRoot, "src"),
  1203  			filepath.Clean(origDir),
  1204  			origRoot,
  1205  			origDir,
  1206  			string(filepath.Separator))
  1207  	}
  1208  
  1209  	return dir, root
  1210  }
  1211  
  1212  // vendoredImportPath returns the vendor-expansion of path when it appears in parent.
  1213  // If parent is x/y/z, then path might expand to x/y/z/vendor/path, x/y/vendor/path,
  1214  // x/vendor/path, vendor/path, or else stay path if none of those exist.
  1215  // vendoredImportPath returns the expanded path or, if no expansion is found, the original.
  1216  func vendoredImportPath(path, parentPath, parentDir, parentRoot string) (found string) {
  1217  	if parentRoot == "" {
  1218  		return path
  1219  	}
  1220  
  1221  	dir, root := dirAndRoot(parentPath, parentDir, parentRoot)
  1222  
  1223  	vpath := "vendor/" + path
  1224  	for i := len(dir); i >= len(root); i-- {
  1225  		if i < len(dir) && dir[i] != filepath.Separator {
  1226  			continue
  1227  		}
  1228  		// Note: checking for the vendor directory before checking
  1229  		// for the vendor/path directory helps us hit the
  1230  		// isDir cache more often. It also helps us prepare a more useful
  1231  		// list of places we looked, to report when an import is not found.
  1232  		if !isDir(filepath.Join(dir[:i], "vendor")) {
  1233  			continue
  1234  		}
  1235  		targ := filepath.Join(dir[:i], vpath)
  1236  		if isDir(targ) && hasGoFiles(targ) {
  1237  			importPath := parentPath
  1238  			if importPath == "command-line-arguments" {
  1239  				// If parent.ImportPath is 'command-line-arguments'.
  1240  				// set to relative directory to root (also chopped root directory)
  1241  				importPath = dir[len(root)+1:]
  1242  			}
  1243  			// We started with parent's dir c:\gopath\src\foo\bar\baz\quux\xyzzy.
  1244  			// We know the import path for parent's dir.
  1245  			// We chopped off some number of path elements and
  1246  			// added vendor\path to produce c:\gopath\src\foo\bar\baz\vendor\path.
  1247  			// Now we want to know the import path for that directory.
  1248  			// Construct it by chopping the same number of path elements
  1249  			// (actually the same number of bytes) from parent's import path
  1250  			// and then append /vendor/path.
  1251  			chopped := len(dir) - i
  1252  			if chopped == len(importPath)+1 {
  1253  				// We walked up from c:\gopath\src\foo\bar
  1254  				// and found c:\gopath\src\vendor\path.
  1255  				// We chopped \foo\bar (length 8) but the import path is "foo/bar" (length 7).
  1256  				// Use "vendor/path" without any prefix.
  1257  				return vpath
  1258  			}
  1259  			return importPath[:len(importPath)-chopped] + "/" + vpath
  1260  		}
  1261  	}
  1262  	return path
  1263  }
  1264  
  1265  var (
  1266  	modulePrefix   = []byte("\nmodule ")
  1267  	goModPathCache par.Cache[string, string]
  1268  )
  1269  
  1270  // goModPath returns the module path in the go.mod in dir, if any.
  1271  func goModPath(dir string) (path string) {
  1272  	return goModPathCache.Do(dir, func() string {
  1273  		data, err := os.ReadFile(filepath.Join(dir, "go.mod"))
  1274  		if err != nil {
  1275  			return ""
  1276  		}
  1277  		var i int
  1278  		if bytes.HasPrefix(data, modulePrefix[1:]) {
  1279  			i = 0
  1280  		} else {
  1281  			i = bytes.Index(data, modulePrefix)
  1282  			if i < 0 {
  1283  				return ""
  1284  			}
  1285  			i++
  1286  		}
  1287  		line := data[i:]
  1288  
  1289  		// Cut line at \n, drop trailing \r if present.
  1290  		if j := bytes.IndexByte(line, '\n'); j >= 0 {
  1291  			line = line[:j]
  1292  		}
  1293  		if line[len(line)-1] == '\r' {
  1294  			line = line[:len(line)-1]
  1295  		}
  1296  		line = line[len("module "):]
  1297  
  1298  		// If quoted, unquote.
  1299  		path = strings.TrimSpace(string(line))
  1300  		if path != "" && path[0] == '"' {
  1301  			s, err := strconv.Unquote(path)
  1302  			if err != nil {
  1303  				return ""
  1304  			}
  1305  			path = s
  1306  		}
  1307  		return path
  1308  	})
  1309  }
  1310  
  1311  // findVersionElement returns the slice indices of the final version element /vN in path.
  1312  // If there is no such element, it returns -1, -1.
  1313  func findVersionElement(path string) (i, j int) {
  1314  	j = len(path)
  1315  	for i = len(path) - 1; i >= 0; i-- {
  1316  		if path[i] == '/' {
  1317  			if isVersionElement(path[i+1 : j]) {
  1318  				return i, j
  1319  			}
  1320  			j = i
  1321  		}
  1322  	}
  1323  	return -1, -1
  1324  }
  1325  
  1326  // isVersionElement reports whether s is a well-formed path version element:
  1327  // v2, v3, v10, etc, but not v0, v05, v1.
  1328  func isVersionElement(s string) bool {
  1329  	if len(s) < 2 || s[0] != 'v' || s[1] == '0' || s[1] == '1' && len(s) == 2 {
  1330  		return false
  1331  	}
  1332  	for i := 1; i < len(s); i++ {
  1333  		if s[i] < '0' || '9' < s[i] {
  1334  			return false
  1335  		}
  1336  	}
  1337  	return true
  1338  }
  1339  
  1340  // moduleImportPath translates import paths found in go modules
  1341  // back down to paths that can be resolved in ordinary builds.
  1342  //
  1343  // Define “new” code as code with a go.mod file in the same directory
  1344  // or a parent directory. If an import in new code says x/y/v2/z but
  1345  // x/y/v2/z does not exist and x/y/go.mod says “module x/y/v2”,
  1346  // then go build will read the import as x/y/z instead.
  1347  // See golang.org/issue/25069.
  1348  func moduleImportPath(path, parentPath, parentDir, parentRoot string) (found string) {
  1349  	if parentRoot == "" {
  1350  		return path
  1351  	}
  1352  
  1353  	// If there are no vN elements in path, leave it alone.
  1354  	// (The code below would do the same, but only after
  1355  	// some other file system accesses that we can avoid
  1356  	// here by returning early.)
  1357  	if i, _ := findVersionElement(path); i < 0 {
  1358  		return path
  1359  	}
  1360  
  1361  	dir, root := dirAndRoot(parentPath, parentDir, parentRoot)
  1362  
  1363  	// Consider dir and parents, up to and including root.
  1364  	for i := len(dir); i >= len(root); i-- {
  1365  		if i < len(dir) && dir[i] != filepath.Separator {
  1366  			continue
  1367  		}
  1368  		if goModPath(dir[:i]) != "" {
  1369  			goto HaveGoMod
  1370  		}
  1371  	}
  1372  	// This code is not in a tree with a go.mod,
  1373  	// so apply no changes to the path.
  1374  	return path
  1375  
  1376  HaveGoMod:
  1377  	// This import is in a tree with a go.mod.
  1378  	// Allow it to refer to code in GOPATH/src/x/y/z as x/y/v2/z
  1379  	// if GOPATH/src/x/y/go.mod says module "x/y/v2",
  1380  
  1381  	// If x/y/v2/z exists, use it unmodified.
  1382  	if bp, _ := cfg.BuildContext.Import(path, "", build.IgnoreVendor); bp.Dir != "" {
  1383  		return path
  1384  	}
  1385  
  1386  	// Otherwise look for a go.mod supplying a version element.
  1387  	// Some version-like elements may appear in paths but not
  1388  	// be module versions; we skip over those to look for module
  1389  	// versions. For example the module m/v2 might have a
  1390  	// package m/v2/api/v1/foo.
  1391  	limit := len(path)
  1392  	for limit > 0 {
  1393  		i, j := findVersionElement(path[:limit])
  1394  		if i < 0 {
  1395  			return path
  1396  		}
  1397  		if bp, _ := cfg.BuildContext.Import(path[:i], "", build.IgnoreVendor); bp.Dir != "" {
  1398  			if mpath := goModPath(bp.Dir); mpath != "" {
  1399  				// Found a valid go.mod file, so we're stopping the search.
  1400  				// If the path is m/v2/p and we found m/go.mod that says
  1401  				// "module m/v2", then we return "m/p".
  1402  				if mpath == path[:j] {
  1403  					return path[:i] + path[j:]
  1404  				}
  1405  				// Otherwise just return the original path.
  1406  				// We didn't find anything worth rewriting,
  1407  				// and the go.mod indicates that we should
  1408  				// not consider parent directories.
  1409  				return path
  1410  			}
  1411  		}
  1412  		limit = i
  1413  	}
  1414  	return path
  1415  }
  1416  
  1417  // hasGoFiles reports whether dir contains any files with names ending in .go.
  1418  // For a vendor check we must exclude directories that contain no .go files.
  1419  // Otherwise it is not possible to vendor just a/b/c and still import the
  1420  // non-vendored a/b. See golang.org/issue/13832.
  1421  func hasGoFiles(dir string) bool {
  1422  	files, _ := os.ReadDir(dir)
  1423  	for _, f := range files {
  1424  		if !f.IsDir() && strings.HasSuffix(f.Name(), ".go") {
  1425  			return true
  1426  		}
  1427  	}
  1428  	return false
  1429  }
  1430  
  1431  // reusePackage reuses package p to satisfy the import at the top
  1432  // of the import stack stk. If this use causes an import loop,
  1433  // reusePackage updates p's error information to record the loop.
  1434  func reusePackage(p *Package, stk *ImportStack) *Package {
  1435  	// We use p.Internal.Imports==nil to detect a package that
  1436  	// is in the midst of its own loadPackage call
  1437  	// (all the recursion below happens before p.Internal.Imports gets set).
  1438  	if p.Internal.Imports == nil {
  1439  		if p.Error == nil {
  1440  			p.Error = &PackageError{
  1441  				ImportStack:   stk.Copy(),
  1442  				Err:           errors.New("import cycle not allowed"),
  1443  				IsImportCycle: true,
  1444  			}
  1445  		} else if !p.Error.IsImportCycle {
  1446  			// If the error is already set, but it does not indicate that
  1447  			// we are in an import cycle, set IsImportCycle so that we don't
  1448  			// end up stuck in a loop down the road.
  1449  			p.Error.IsImportCycle = true
  1450  		}
  1451  		p.Incomplete = true
  1452  	}
  1453  	// Don't rewrite the import stack in the error if we have an import cycle.
  1454  	// If we do, we'll lose the path that describes the cycle.
  1455  	if p.Error != nil && p.Error.ImportStack != nil &&
  1456  		!p.Error.IsImportCycle && stk.shorterThan(p.Error.ImportStack.Pkgs()) {
  1457  		p.Error.ImportStack = stk.Copy()
  1458  	}
  1459  	return p
  1460  }
  1461  
  1462  // disallowInternal checks that srcDir (containing package importerPath, if non-empty)
  1463  // is allowed to import p.
  1464  // If the import is allowed, disallowInternal returns the original package p.
  1465  // If not, it returns a new package containing just an appropriate error.
  1466  func disallowInternal(ctx context.Context, srcDir string, importer *Package, importerPath string, p *Package, stk *ImportStack) *PackageError {
  1467  	// golang.org/s/go14internal:
  1468  	// An import of a path containing the element “internal”
  1469  	// is disallowed if the importing code is outside the tree
  1470  	// rooted at the parent of the “internal” directory.
  1471  
  1472  	// There was an error loading the package; stop here.
  1473  	if p.Error != nil {
  1474  		return nil
  1475  	}
  1476  
  1477  	// The generated 'testmain' package is allowed to access testing/internal/...,
  1478  	// as if it were generated into the testing directory tree
  1479  	// (it's actually in a temporary directory outside any Go tree).
  1480  	// This cleans up a former kludge in passing functionality to the testing package.
  1481  	if str.HasPathPrefix(p.ImportPath, "testing/internal") && importerPath == "testmain" {
  1482  		return nil
  1483  	}
  1484  
  1485  	// We can't check standard packages with gccgo.
  1486  	if cfg.BuildContext.Compiler == "gccgo" && p.Standard {
  1487  		return nil
  1488  	}
  1489  
  1490  	// The sort package depends on internal/reflectlite, but during bootstrap
  1491  	// the path rewriting causes the normal internal checks to fail.
  1492  	// Instead, just ignore the internal rules during bootstrap.
  1493  	if p.Standard && strings.HasPrefix(importerPath, "bootstrap/") {
  1494  		return nil
  1495  	}
  1496  
  1497  	// importerPath is empty: we started
  1498  	// with a name given on the command line, not an
  1499  	// import. Anything listed on the command line is fine.
  1500  	if importerPath == "" {
  1501  		return nil
  1502  	}
  1503  
  1504  	// Check for "internal" element: three cases depending on begin of string and/or end of string.
  1505  	i, ok := findInternal(p.ImportPath)
  1506  	if !ok {
  1507  		return nil
  1508  	}
  1509  
  1510  	// Internal is present.
  1511  	// Map import path back to directory corresponding to parent of internal.
  1512  	if i > 0 {
  1513  		i-- // rewind over slash in ".../internal"
  1514  	}
  1515  
  1516  	// FIPS-140 snapshots are special, because they comes from a non-GOROOT
  1517  	// directory, so the usual directory rules don't work apply, or rather they
  1518  	// apply differently depending on whether we are using a snapshot or the
  1519  	// in-tree copy of the code. We apply a consistent rule here:
  1520  	// crypto/internal/fips140 can only see crypto/internal, never top-of-tree internal.
  1521  	// Similarly, crypto/... can see crypto/internal/fips140 even though the usual rules
  1522  	// would not allow it in snapshot mode.
  1523  	if str.HasPathPrefix(importerPath, "crypto") && str.HasPathPrefix(p.ImportPath, "crypto/internal/fips140") {
  1524  		return nil // crypto can use crypto/internal/fips140
  1525  	}
  1526  	if str.HasPathPrefix(importerPath, "crypto/internal/fips140") {
  1527  		if str.HasPathPrefix(p.ImportPath, "crypto/internal") {
  1528  			return nil // crypto/internal/fips140 can use crypto/internal
  1529  		}
  1530  		goto Error
  1531  	}
  1532  
  1533  	if p.Module == nil {
  1534  		parent := p.Dir[:i+len(p.Dir)-len(p.ImportPath)]
  1535  
  1536  		if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1537  			return nil
  1538  		}
  1539  
  1540  		// Look for symlinks before reporting error.
  1541  		srcDir = expandPath(srcDir)
  1542  		parent = expandPath(parent)
  1543  		if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1544  			return nil
  1545  		}
  1546  	} else {
  1547  		// p is in a module, so make it available based on the importer's import path instead
  1548  		// of the file path (https://golang.org/issue/23970).
  1549  		if importer.Internal.CmdlineFiles {
  1550  			// The importer is a list of command-line files.
  1551  			// Pretend that the import path is the import path of the
  1552  			// directory containing them.
  1553  			// If the directory is outside the main modules, this will resolve to ".",
  1554  			// which is not a prefix of any valid module.
  1555  			importerPath, _ = modload.MainModules.DirImportPath(ctx, importer.Dir)
  1556  		}
  1557  		parentOfInternal := p.ImportPath[:i]
  1558  		if str.HasPathPrefix(importerPath, parentOfInternal) {
  1559  			return nil
  1560  		}
  1561  	}
  1562  
  1563  Error:
  1564  	// Internal is present, and srcDir is outside parent's tree. Not allowed.
  1565  	perr := &PackageError{
  1566  		alwaysPrintStack: true,
  1567  		ImportStack:      stk.Copy(),
  1568  		Err:              ImportErrorf(p.ImportPath, "use of internal package %s not allowed", p.ImportPath),
  1569  	}
  1570  	return perr
  1571  }
  1572  
  1573  // findInternal looks for the final "internal" path element in the given import path.
  1574  // If there isn't one, findInternal returns ok=false.
  1575  // Otherwise, findInternal returns ok=true and the index of the "internal".
  1576  func findInternal(path string) (index int, ok bool) {
  1577  	// Three cases, depending on internal at start/end of string or not.
  1578  	// The order matters: we must return the index of the final element,
  1579  	// because the final one produces the most restrictive requirement
  1580  	// on the importer.
  1581  	switch {
  1582  	case strings.HasSuffix(path, "/internal"):
  1583  		return len(path) - len("internal"), true
  1584  	case strings.Contains(path, "/internal/"):
  1585  		return strings.LastIndex(path, "/internal/") + 1, true
  1586  	case path == "internal", strings.HasPrefix(path, "internal/"):
  1587  		return 0, true
  1588  	}
  1589  	return 0, false
  1590  }
  1591  
  1592  // disallowVendor checks that srcDir is allowed to import p as path.
  1593  // If the import is allowed, disallowVendor returns the original package p.
  1594  // If not, it returns a PackageError.
  1595  func disallowVendor(srcDir string, path string, importerPath string, p *Package, stk *ImportStack) *PackageError {
  1596  	// If the importerPath is empty, we started
  1597  	// with a name given on the command line, not an
  1598  	// import. Anything listed on the command line is fine.
  1599  	if importerPath == "" {
  1600  		return nil
  1601  	}
  1602  
  1603  	if perr := disallowVendorVisibility(srcDir, p, importerPath, stk); perr != nil {
  1604  		return perr
  1605  	}
  1606  
  1607  	// Paths like x/vendor/y must be imported as y, never as x/vendor/y.
  1608  	if i, ok := FindVendor(path); ok {
  1609  		perr := &PackageError{
  1610  			ImportStack: stk.Copy(),
  1611  			Err:         ImportErrorf(path, "%s must be imported as %s", path, path[i+len("vendor/"):]),
  1612  		}
  1613  		return perr
  1614  	}
  1615  
  1616  	return nil
  1617  }
  1618  
  1619  // disallowVendorVisibility checks that srcDir is allowed to import p.
  1620  // The rules are the same as for /internal/ except that a path ending in /vendor
  1621  // is not subject to the rules, only subdirectories of vendor.
  1622  // This allows people to have packages and commands named vendor,
  1623  // for maximal compatibility with existing source trees.
  1624  func disallowVendorVisibility(srcDir string, p *Package, importerPath string, stk *ImportStack) *PackageError {
  1625  	// The stack does not include p.ImportPath.
  1626  	// If there's nothing on the stack, we started
  1627  	// with a name given on the command line, not an
  1628  	// import. Anything listed on the command line is fine.
  1629  	if importerPath == "" {
  1630  		return nil
  1631  	}
  1632  
  1633  	// Check for "vendor" element.
  1634  	i, ok := FindVendor(p.ImportPath)
  1635  	if !ok {
  1636  		return nil
  1637  	}
  1638  
  1639  	// Vendor is present.
  1640  	// Map import path back to directory corresponding to parent of vendor.
  1641  	if i > 0 {
  1642  		i-- // rewind over slash in ".../vendor"
  1643  	}
  1644  	truncateTo := i + len(p.Dir) - len(p.ImportPath)
  1645  	if truncateTo < 0 || len(p.Dir) < truncateTo {
  1646  		return nil
  1647  	}
  1648  	parent := p.Dir[:truncateTo]
  1649  	if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1650  		return nil
  1651  	}
  1652  
  1653  	// Look for symlinks before reporting error.
  1654  	srcDir = expandPath(srcDir)
  1655  	parent = expandPath(parent)
  1656  	if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1657  		return nil
  1658  	}
  1659  
  1660  	// Vendor is present, and srcDir is outside parent's tree. Not allowed.
  1661  
  1662  	perr := &PackageError{
  1663  		ImportStack: stk.Copy(),
  1664  		Err:         errors.New("use of vendored package not allowed"),
  1665  	}
  1666  	return perr
  1667  }
  1668  
  1669  // FindVendor looks for the last non-terminating "vendor" path element in the given import path.
  1670  // If there isn't one, FindVendor returns ok=false.
  1671  // Otherwise, FindVendor returns ok=true and the index of the "vendor".
  1672  //
  1673  // Note that terminating "vendor" elements don't count: "x/vendor" is its own package,
  1674  // not the vendored copy of an import "" (the empty import path).
  1675  // This will allow people to have packages or commands named vendor.
  1676  // This may help reduce breakage, or it may just be confusing. We'll see.
  1677  func FindVendor(path string) (index int, ok bool) {
  1678  	// Two cases, depending on internal at start of string or not.
  1679  	// The order matters: we must return the index of the final element,
  1680  	// because the final one is where the effective import path starts.
  1681  	switch {
  1682  	case strings.Contains(path, "/vendor/"):
  1683  		return strings.LastIndex(path, "/vendor/") + 1, true
  1684  	case strings.HasPrefix(path, "vendor/"):
  1685  		return 0, true
  1686  	}
  1687  	return 0, false
  1688  }
  1689  
  1690  type TargetDir int
  1691  
  1692  const (
  1693  	ToTool    TargetDir = iota // to GOROOT/pkg/tool (default for cmd/*)
  1694  	ToBin                      // to bin dir inside package root (default for non-cmd/*)
  1695  	StalePath                  // an old import path; fail to build
  1696  )
  1697  
  1698  // InstallTargetDir reports the target directory for installing the command p.
  1699  func InstallTargetDir(p *Package) TargetDir {
  1700  	if strings.HasPrefix(p.ImportPath, "code.google.com/p/go.tools/cmd/") {
  1701  		return StalePath
  1702  	}
  1703  	if p.Goroot && strings.HasPrefix(p.ImportPath, "cmd/") && p.Name == "main" {
  1704  		switch p.ImportPath {
  1705  		case "cmd/go", "cmd/gofmt":
  1706  			return ToBin
  1707  		}
  1708  		return ToTool
  1709  	}
  1710  	return ToBin
  1711  }
  1712  
  1713  var cgoExclude = map[string]bool{
  1714  	"runtime/cgo": true,
  1715  }
  1716  
  1717  var cgoSyscallExclude = map[string]bool{
  1718  	"runtime/cgo":  true,
  1719  	"runtime/race": true,
  1720  	"runtime/msan": true,
  1721  	"runtime/asan": true,
  1722  }
  1723  
  1724  var foldPath = make(map[string]string)
  1725  
  1726  // exeFromImportPath returns an executable name
  1727  // for a package using the import path.
  1728  //
  1729  // The executable name is the last element of the import path.
  1730  // In module-aware mode, an additional rule is used on import paths
  1731  // consisting of two or more path elements. If the last element is
  1732  // a vN path element specifying the major version, then the
  1733  // second last element of the import path is used instead.
  1734  func (p *Package) exeFromImportPath() string {
  1735  	_, elem := pathpkg.Split(p.ImportPath)
  1736  	if cfg.ModulesEnabled {
  1737  		// If this is example.com/mycmd/v2, it's more useful to
  1738  		// install it as mycmd than as v2. See golang.org/issue/24667.
  1739  		if elem != p.ImportPath && isVersionElement(elem) {
  1740  			_, elem = pathpkg.Split(pathpkg.Dir(p.ImportPath))
  1741  		}
  1742  	}
  1743  	return elem
  1744  }
  1745  
  1746  // exeFromFiles returns an executable name for a package
  1747  // using the first element in GoFiles or CgoFiles collections without the prefix.
  1748  //
  1749  // Returns empty string in case of empty collection.
  1750  func (p *Package) exeFromFiles() string {
  1751  	var src string
  1752  	if len(p.GoFiles) > 0 {
  1753  		src = p.GoFiles[0]
  1754  	} else if len(p.CgoFiles) > 0 {
  1755  		src = p.CgoFiles[0]
  1756  	} else {
  1757  		return ""
  1758  	}
  1759  	_, elem := filepath.Split(src)
  1760  	return elem[:len(elem)-len(".go")]
  1761  }
  1762  
  1763  // DefaultExecName returns the default executable name for a package
  1764  func (p *Package) DefaultExecName() string {
  1765  	if p.Internal.CmdlineFiles {
  1766  		return p.exeFromFiles()
  1767  	}
  1768  	return p.exeFromImportPath()
  1769  }
  1770  
  1771  // load populates p using information from bp, err, which should
  1772  // be the result of calling build.Context.Import.
  1773  // stk contains the import stack, not including path itself.
  1774  func (p *Package) load(ctx context.Context, opts PackageOpts, path string, stk *ImportStack, importPos []token.Position, bp *build.Package, err error) {
  1775  	p.copyBuild(opts, bp)
  1776  
  1777  	// The localPrefix is the path we interpret ./ imports relative to,
  1778  	// if we support them at all (not in module mode!).
  1779  	// Synthesized main packages sometimes override this.
  1780  	if p.Internal.Local && !cfg.ModulesEnabled {
  1781  		p.Internal.LocalPrefix = dirToImportPath(p.Dir)
  1782  	}
  1783  
  1784  	// setError sets p.Error if it hasn't already been set. We may proceed
  1785  	// after encountering some errors so that 'go list -e' has more complete
  1786  	// output. If there's more than one error, we should report the first.
  1787  	setError := func(err error) {
  1788  		if p.Error == nil {
  1789  			p.Error = &PackageError{
  1790  				ImportStack: stk.Copy(),
  1791  				Err:         err,
  1792  			}
  1793  			p.Incomplete = true
  1794  
  1795  			// Add the importer's position information if the import position exists, and
  1796  			// the current package being examined is the importer.
  1797  			// If we have not yet accepted package p onto the import stack,
  1798  			// then the cause of the error is not within p itself: the error
  1799  			// must be either in an explicit command-line argument,
  1800  			// or on the importer side (indicated by a non-empty importPos).
  1801  			top, ok := stk.Top()
  1802  			if ok && path != top.Pkg && len(importPos) > 0 {
  1803  				p.Error.setPos(importPos)
  1804  			}
  1805  		}
  1806  	}
  1807  
  1808  	if err != nil {
  1809  		p.Incomplete = true
  1810  		p.setLoadPackageDataError(err, path, stk, importPos)
  1811  	}
  1812  
  1813  	useBindir := p.Name == "main"
  1814  	if !p.Standard {
  1815  		switch cfg.BuildBuildmode {
  1816  		case "c-archive", "c-shared", "plugin":
  1817  			useBindir = false
  1818  		}
  1819  	}
  1820  
  1821  	if useBindir {
  1822  		// Report an error when the old code.google.com/p/go.tools paths are used.
  1823  		if InstallTargetDir(p) == StalePath {
  1824  			// TODO(matloob): remove this branch, and StalePath itself. code.google.com/p/go is so
  1825  			// old, even this code checking for it is stale now!
  1826  			newPath := strings.Replace(p.ImportPath, "code.google.com/p/go.", "golang.org/x/", 1)
  1827  			e := ImportErrorf(p.ImportPath, "the %v command has moved; use %v instead.", p.ImportPath, newPath)
  1828  			setError(e)
  1829  			return
  1830  		}
  1831  		elem := p.DefaultExecName() + cfg.ExeSuffix
  1832  		full := filepath.Join(cfg.BuildContext.GOOS+"_"+cfg.BuildContext.GOARCH, elem)
  1833  		if cfg.BuildContext.GOOS != runtime.GOOS || cfg.BuildContext.GOARCH != runtime.GOARCH {
  1834  			// Install cross-compiled binaries to subdirectories of bin.
  1835  			elem = full
  1836  		}
  1837  		if p.Internal.Build.BinDir == "" && cfg.ModulesEnabled {
  1838  			p.Internal.Build.BinDir = modload.BinDir()
  1839  		}
  1840  		if p.Internal.Build.BinDir != "" {
  1841  			// Install to GOBIN or bin of GOPATH entry.
  1842  			p.Target = filepath.Join(p.Internal.Build.BinDir, elem)
  1843  			if !p.Goroot && strings.Contains(elem, string(filepath.Separator)) && cfg.GOBIN != "" {
  1844  				// Do not create $GOBIN/goos_goarch/elem.
  1845  				p.Target = ""
  1846  				p.Internal.GobinSubdir = true
  1847  			}
  1848  		}
  1849  		if InstallTargetDir(p) == ToTool {
  1850  			// This is for 'go tool'.
  1851  			// Override all the usual logic and force it into the tool directory.
  1852  			if cfg.BuildToolchainName == "gccgo" {
  1853  				p.Target = filepath.Join(build.ToolDir, elem)
  1854  			} else {
  1855  				p.Target = filepath.Join(cfg.GOROOTpkg, "tool", full)
  1856  			}
  1857  		}
  1858  	} else if p.Internal.Local {
  1859  		// Local import turned into absolute path.
  1860  		// No permanent install target.
  1861  		p.Target = ""
  1862  	} else if p.Standard && cfg.BuildContext.Compiler == "gccgo" {
  1863  		// gccgo has a preinstalled standard library that cmd/go cannot rebuild.
  1864  		p.Target = ""
  1865  	} else {
  1866  		p.Target = p.Internal.Build.PkgObj
  1867  		if cfg.BuildBuildmode == "shared" && p.Internal.Build.PkgTargetRoot != "" {
  1868  			// TODO(matloob): This shouldn't be necessary, but the cmd/cgo/internal/testshared
  1869  			// test fails without Target set for this condition. Figure out why and
  1870  			// fix it.
  1871  			p.Target = filepath.Join(p.Internal.Build.PkgTargetRoot, p.ImportPath+".a")
  1872  		}
  1873  		if cfg.BuildLinkshared && p.Internal.Build.PkgTargetRoot != "" {
  1874  			// TODO(bcmills): The reliance on PkgTargetRoot implies that -linkshared does
  1875  			// not work for any package that lacks a PkgTargetRoot — such as a non-main
  1876  			// package in module mode. We should probably fix that.
  1877  			targetPrefix := filepath.Join(p.Internal.Build.PkgTargetRoot, p.ImportPath)
  1878  			p.Target = targetPrefix + ".a"
  1879  			shlibnamefile := targetPrefix + ".shlibname"
  1880  			shlib, err := os.ReadFile(shlibnamefile)
  1881  			if err != nil && !os.IsNotExist(err) {
  1882  				base.Fatalf("reading shlibname: %v", err)
  1883  			}
  1884  			if err == nil {
  1885  				libname := strings.TrimSpace(string(shlib))
  1886  				if cfg.BuildContext.Compiler == "gccgo" {
  1887  					p.Shlib = filepath.Join(p.Internal.Build.PkgTargetRoot, "shlibs", libname)
  1888  				} else {
  1889  					p.Shlib = filepath.Join(p.Internal.Build.PkgTargetRoot, libname)
  1890  				}
  1891  			}
  1892  		}
  1893  	}
  1894  
  1895  	// Build augmented import list to add implicit dependencies.
  1896  	// Be careful not to add imports twice, just to avoid confusion.
  1897  	importPaths := p.Imports
  1898  	addImport := func(path string, forCompiler bool) {
  1899  		for _, p := range importPaths {
  1900  			if path == p {
  1901  				return
  1902  			}
  1903  		}
  1904  		importPaths = append(importPaths, path)
  1905  		if forCompiler {
  1906  			p.Internal.CompiledImports = append(p.Internal.CompiledImports, path)
  1907  		}
  1908  	}
  1909  
  1910  	if !opts.IgnoreImports {
  1911  		// Cgo translation adds imports of "unsafe", "runtime/cgo" and "syscall",
  1912  		// except for certain packages, to avoid circular dependencies.
  1913  		if p.UsesCgo() {
  1914  			addImport("unsafe", true)
  1915  		}
  1916  		if p.UsesCgo() && (!p.Standard || !cgoExclude[p.ImportPath]) && cfg.BuildContext.Compiler != "gccgo" {
  1917  			addImport("runtime/cgo", true)
  1918  		}
  1919  		if p.UsesCgo() && (!p.Standard || !cgoSyscallExclude[p.ImportPath]) {
  1920  			addImport("syscall", true)
  1921  		}
  1922  
  1923  		// SWIG adds imports of some standard packages.
  1924  		if p.UsesSwig() {
  1925  			addImport("unsafe", true)
  1926  			if cfg.BuildContext.Compiler != "gccgo" {
  1927  				addImport("runtime/cgo", true)
  1928  			}
  1929  			addImport("syscall", true)
  1930  			addImport("sync", true)
  1931  
  1932  			// TODO: The .swig and .swigcxx files can use
  1933  			// %go_import directives to import other packages.
  1934  		}
  1935  
  1936  		// The linker loads implicit dependencies.
  1937  		if p.Name == "main" && !p.Internal.ForceLibrary {
  1938  			ldDeps, err := LinkerDeps(p)
  1939  			if err != nil {
  1940  				setError(err)
  1941  				return
  1942  			}
  1943  			for _, dep := range ldDeps {
  1944  				addImport(dep, false)
  1945  			}
  1946  		}
  1947  	}
  1948  
  1949  	// Check for case-insensitive collisions of import paths.
  1950  	// If modifying, consider changing checkPathCollisions() in
  1951  	// src/cmd/go/internal/modcmd/vendor.go
  1952  	fold := str.ToFold(p.ImportPath)
  1953  	if other := foldPath[fold]; other == "" {
  1954  		foldPath[fold] = p.ImportPath
  1955  	} else if other != p.ImportPath {
  1956  		setError(ImportErrorf(p.ImportPath, "case-insensitive import collision: %q and %q", p.ImportPath, other))
  1957  		return
  1958  	}
  1959  
  1960  	if !SafeArg(p.ImportPath) {
  1961  		setError(ImportErrorf(p.ImportPath, "invalid import path %q", p.ImportPath))
  1962  		return
  1963  	}
  1964  
  1965  	// Errors after this point are caused by this package, not the importing
  1966  	// package. Pushing the path here prevents us from reporting the error
  1967  	// with the position of the import declaration.
  1968  	stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
  1969  	defer stk.Pop()
  1970  
  1971  	pkgPath := p.ImportPath
  1972  	if p.Internal.CmdlineFiles {
  1973  		pkgPath = "command-line-arguments"
  1974  	}
  1975  	if cfg.ModulesEnabled {
  1976  		p.Module = modload.PackageModuleInfo(ctx, pkgPath)
  1977  	}
  1978  	p.DefaultGODEBUG = defaultGODEBUG(p, nil, nil, nil)
  1979  
  1980  	if !opts.SuppressEmbedFiles {
  1981  		p.EmbedFiles, p.Internal.Embed, err = resolveEmbed(p.Dir, p.EmbedPatterns)
  1982  		if err != nil {
  1983  			p.Incomplete = true
  1984  			setError(err)
  1985  			embedErr := err.(*EmbedError)
  1986  			p.Error.setPos(p.Internal.Build.EmbedPatternPos[embedErr.Pattern])
  1987  		}
  1988  	}
  1989  
  1990  	// Check for case-insensitive collision of input files.
  1991  	// To avoid problems on case-insensitive files, we reject any package
  1992  	// where two different input files have equal names under a case-insensitive
  1993  	// comparison.
  1994  	inputs := p.AllFiles()
  1995  	f1, f2 := str.FoldDup(inputs)
  1996  	if f1 != "" {
  1997  		setError(fmt.Errorf("case-insensitive file name collision: %q and %q", f1, f2))
  1998  		return
  1999  	}
  2000  
  2001  	// If first letter of input file is ASCII, it must be alphanumeric.
  2002  	// This avoids files turning into flags when invoking commands,
  2003  	// and other problems we haven't thought of yet.
  2004  	// Also, _cgo_ files must be generated by us, not supplied.
  2005  	// They are allowed to have //go:cgo_ldflag directives.
  2006  	// The directory scan ignores files beginning with _,
  2007  	// so we shouldn't see any _cgo_ files anyway, but just be safe.
  2008  	for _, file := range inputs {
  2009  		if !SafeArg(file) || strings.HasPrefix(file, "_cgo_") {
  2010  			setError(fmt.Errorf("invalid input file name %q", file))
  2011  			return
  2012  		}
  2013  	}
  2014  	if name := pathpkg.Base(p.ImportPath); !SafeArg(name) {
  2015  		setError(fmt.Errorf("invalid input directory name %q", name))
  2016  		return
  2017  	}
  2018  	if strings.ContainsAny(p.Dir, "\r\n") {
  2019  		setError(fmt.Errorf("invalid package directory %q", p.Dir))
  2020  		return
  2021  	}
  2022  
  2023  	// Build list of imported packages and full dependency list.
  2024  	imports := make([]*Package, 0, len(p.Imports))
  2025  	for i, path := range importPaths {
  2026  		if path == "C" {
  2027  			continue
  2028  		}
  2029  		p1, err := loadImport(ctx, opts, nil, path, p.Dir, p, stk, p.Internal.Build.ImportPos[path], ResolveImport)
  2030  		if err != nil && p.Error == nil {
  2031  			p.Error = err
  2032  			p.Incomplete = true
  2033  		}
  2034  
  2035  		path = p1.ImportPath
  2036  		importPaths[i] = path
  2037  		if i < len(p.Imports) {
  2038  			p.Imports[i] = path
  2039  		}
  2040  
  2041  		imports = append(imports, p1)
  2042  		if p1.Incomplete {
  2043  			p.Incomplete = true
  2044  		}
  2045  	}
  2046  	p.Internal.Imports = imports
  2047  	if p.Error == nil && p.Name == "main" && !p.Internal.ForceLibrary && !p.Incomplete && !opts.SuppressBuildInfo {
  2048  		// TODO(bcmills): loading VCS metadata can be fairly slow.
  2049  		// Consider starting this as a background goroutine and retrieving the result
  2050  		// asynchronously when we're actually ready to build the package, or when we
  2051  		// actually need to evaluate whether the package's metadata is stale.
  2052  		p.setBuildInfo(ctx, opts.AutoVCS)
  2053  	}
  2054  
  2055  	// If cgo is not enabled, ignore cgo supporting sources
  2056  	// just as we ignore go files containing import "C".
  2057  	if !cfg.BuildContext.CgoEnabled {
  2058  		p.CFiles = nil
  2059  		p.CXXFiles = nil
  2060  		p.MFiles = nil
  2061  		p.SwigFiles = nil
  2062  		p.SwigCXXFiles = nil
  2063  		// Note that SFiles are okay (they go to the Go assembler)
  2064  		// and HFiles are okay (they might be used by the SFiles).
  2065  		// Also Sysofiles are okay (they might not contain object
  2066  		// code; see issue #16050).
  2067  	}
  2068  
  2069  	// The gc toolchain only permits C source files with cgo or SWIG.
  2070  	if len(p.CFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() && cfg.BuildContext.Compiler == "gc" {
  2071  		setError(fmt.Errorf("C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CFiles, " ")))
  2072  		return
  2073  	}
  2074  
  2075  	// C++, Objective-C, and Fortran source files are permitted only with cgo or SWIG,
  2076  	// regardless of toolchain.
  2077  	if len(p.CXXFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
  2078  		setError(fmt.Errorf("C++ source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CXXFiles, " ")))
  2079  		return
  2080  	}
  2081  	if len(p.MFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
  2082  		setError(fmt.Errorf("Objective-C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.MFiles, " ")))
  2083  		return
  2084  	}
  2085  	if len(p.FFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
  2086  		setError(fmt.Errorf("Fortran source files not allowed when not using cgo or SWIG: %s", strings.Join(p.FFiles, " ")))
  2087  		return
  2088  	}
  2089  }
  2090  
  2091  // An EmbedError indicates a problem with a go:embed directive.
  2092  type EmbedError struct {
  2093  	Pattern string
  2094  	Err     error
  2095  }
  2096  
  2097  func (e *EmbedError) Error() string {
  2098  	return fmt.Sprintf("pattern %s: %v", e.Pattern, e.Err)
  2099  }
  2100  
  2101  func (e *EmbedError) Unwrap() error {
  2102  	return e.Err
  2103  }
  2104  
  2105  // ResolveEmbed resolves //go:embed patterns and returns only the file list.
  2106  // For use by go mod vendor to find embedded files it should copy into the
  2107  // vendor directory.
  2108  // TODO(#42504): Once go mod vendor uses load.PackagesAndErrors, just
  2109  // call (*Package).ResolveEmbed
  2110  func ResolveEmbed(dir string, patterns []string) ([]string, error) {
  2111  	files, _, err := resolveEmbed(dir, patterns)
  2112  	return files, err
  2113  }
  2114  
  2115  var embedfollowsymlinks = godebug.New("embedfollowsymlinks")
  2116  
  2117  // resolveEmbed resolves //go:embed patterns to precise file lists.
  2118  // It sets files to the list of unique files matched (for go list),
  2119  // and it sets pmap to the more precise mapping from
  2120  // patterns to files.
  2121  func resolveEmbed(pkgdir string, patterns []string) (files []string, pmap map[string][]string, err error) {
  2122  	var pattern string
  2123  	defer func() {
  2124  		if err != nil {
  2125  			err = &EmbedError{
  2126  				Pattern: pattern,
  2127  				Err:     err,
  2128  			}
  2129  		}
  2130  	}()
  2131  
  2132  	// TODO(rsc): All these messages need position information for better error reports.
  2133  	pmap = make(map[string][]string)
  2134  	have := make(map[string]int)
  2135  	dirOK := make(map[string]bool)
  2136  	pid := 0 // pattern ID, to allow reuse of have map
  2137  	for _, pattern = range patterns {
  2138  		pid++
  2139  
  2140  		glob, all := strings.CutPrefix(pattern, "all:")
  2141  		// Check pattern is valid for //go:embed.
  2142  		if _, err := pathpkg.Match(glob, ""); err != nil || !validEmbedPattern(glob) {
  2143  			return nil, nil, fmt.Errorf("invalid pattern syntax")
  2144  		}
  2145  
  2146  		// Glob to find matches.
  2147  		match, err := fsys.Glob(str.QuoteGlob(str.WithFilePathSeparator(pkgdir)) + filepath.FromSlash(glob))
  2148  		if err != nil {
  2149  			return nil, nil, err
  2150  		}
  2151  
  2152  		// Filter list of matches down to the ones that will still exist when
  2153  		// the directory is packaged up as a module. (If p.Dir is in the module cache,
  2154  		// only those files exist already, but if p.Dir is in the current module,
  2155  		// then there may be other things lying around, like symbolic links or .git directories.)
  2156  		var list []string
  2157  		for _, file := range match {
  2158  			// relative path to p.Dir which begins without prefix slash
  2159  			rel := filepath.ToSlash(str.TrimFilePathPrefix(file, pkgdir))
  2160  
  2161  			what := "file"
  2162  			info, err := fsys.Lstat(file)
  2163  			if err != nil {
  2164  				return nil, nil, err
  2165  			}
  2166  			if info.IsDir() {
  2167  				what = "directory"
  2168  			}
  2169  
  2170  			// Check that directories along path do not begin a new module
  2171  			// (do not contain a go.mod).
  2172  			for dir := file; len(dir) > len(pkgdir)+1 && !dirOK[dir]; dir = filepath.Dir(dir) {
  2173  				if _, err := fsys.Stat(filepath.Join(dir, "go.mod")); err == nil {
  2174  					return nil, nil, fmt.Errorf("cannot embed %s %s: in different module", what, rel)
  2175  				}
  2176  				if dir != file {
  2177  					if info, err := fsys.Lstat(dir); err == nil && !info.IsDir() {
  2178  						return nil, nil, fmt.Errorf("cannot embed %s %s: in non-directory %s", what, rel, dir[len(pkgdir)+1:])
  2179  					}
  2180  				}
  2181  				dirOK[dir] = true
  2182  				if elem := filepath.Base(dir); isBadEmbedName(elem) {
  2183  					if dir == file {
  2184  						return nil, nil, fmt.Errorf("cannot embed %s %s: invalid name %s", what, rel, elem)
  2185  					} else {
  2186  						return nil, nil, fmt.Errorf("cannot embed %s %s: in invalid directory %s", what, rel, elem)
  2187  					}
  2188  				}
  2189  			}
  2190  
  2191  			switch {
  2192  			default:
  2193  				return nil, nil, fmt.Errorf("cannot embed irregular file %s", rel)
  2194  
  2195  			case info.Mode().IsRegular():
  2196  				if have[rel] != pid {
  2197  					have[rel] = pid
  2198  					list = append(list, rel)
  2199  				}
  2200  
  2201  			// If the embedfollowsymlinks GODEBUG is set to 1, allow the leaf file to be a
  2202  			// symlink (#59924). We don't allow directories to be symlinks and have already
  2203  			// checked that none of the parent directories of the file are symlinks in the
  2204  			// loop above. The file pointed to by the symlink must be a regular file.
  2205  			case embedfollowsymlinks.Value() == "1" && info.Mode()&fs.ModeType == fs.ModeSymlink:
  2206  				info, err := fsys.Stat(file)
  2207  				if err != nil {
  2208  					return nil, nil, err
  2209  				}
  2210  				if !info.Mode().IsRegular() {
  2211  					return nil, nil, fmt.Errorf("cannot embed irregular file %s", rel)
  2212  				}
  2213  				if have[rel] != pid {
  2214  					embedfollowsymlinks.IncNonDefault()
  2215  					have[rel] = pid
  2216  					list = append(list, rel)
  2217  				}
  2218  
  2219  			case info.IsDir():
  2220  				// Gather all files in the named directory, stopping at module boundaries
  2221  				// and ignoring files that wouldn't be packaged into a module.
  2222  				count := 0
  2223  				err := fsys.WalkDir(file, func(path string, d fs.DirEntry, err error) error {
  2224  					if err != nil {
  2225  						return err
  2226  					}
  2227  					rel := filepath.ToSlash(str.TrimFilePathPrefix(path, pkgdir))
  2228  					name := d.Name()
  2229  					if path != file && (isBadEmbedName(name) || ((name[0] == '.' || name[0] == '_') && !all)) {
  2230  						// Avoid hidden files that user may not know about.
  2231  						// See golang.org/issue/42328.
  2232  						if d.IsDir() {
  2233  							return fs.SkipDir
  2234  						}
  2235  						// Ignore hidden files.
  2236  						if name[0] == '.' || name[0] == '_' {
  2237  							return nil
  2238  						}
  2239  						// Error on bad embed names.
  2240  						// See golang.org/issue/54003.
  2241  						if isBadEmbedName(name) {
  2242  							return fmt.Errorf("cannot embed file %s: invalid name %s", rel, name)
  2243  						}
  2244  						return nil
  2245  					}
  2246  					if d.IsDir() {
  2247  						if _, err := fsys.Stat(filepath.Join(path, "go.mod")); err == nil {
  2248  							return filepath.SkipDir
  2249  						}
  2250  						return nil
  2251  					}
  2252  					if !d.Type().IsRegular() {
  2253  						return nil
  2254  					}
  2255  					count++
  2256  					if have[rel] != pid {
  2257  						have[rel] = pid
  2258  						list = append(list, rel)
  2259  					}
  2260  					return nil
  2261  				})
  2262  				if err != nil {
  2263  					return nil, nil, err
  2264  				}
  2265  				if count == 0 {
  2266  					return nil, nil, fmt.Errorf("cannot embed directory %s: contains no embeddable files", rel)
  2267  				}
  2268  			}
  2269  		}
  2270  
  2271  		if len(list) == 0 {
  2272  			return nil, nil, fmt.Errorf("no matching files found")
  2273  		}
  2274  		sort.Strings(list)
  2275  		pmap[pattern] = list
  2276  	}
  2277  
  2278  	for file := range have {
  2279  		files = append(files, file)
  2280  	}
  2281  	sort.Strings(files)
  2282  	return files, pmap, nil
  2283  }
  2284  
  2285  func validEmbedPattern(pattern string) bool {
  2286  	return pattern != "." && fs.ValidPath(pattern)
  2287  }
  2288  
  2289  // isBadEmbedName reports whether name is the base name of a file that
  2290  // can't or won't be included in modules and therefore shouldn't be treated
  2291  // as existing for embedding.
  2292  func isBadEmbedName(name string) bool {
  2293  	if err := module.CheckFilePath(name); err != nil {
  2294  		return true
  2295  	}
  2296  	switch name {
  2297  	// Empty string should be impossible but make it bad.
  2298  	case "":
  2299  		return true
  2300  	// Version control directories won't be present in module.
  2301  	case ".bzr", ".hg", ".git", ".svn":
  2302  		return true
  2303  	}
  2304  	return false
  2305  }
  2306  
  2307  // vcsStatusCache maps repository directories (string)
  2308  // to their VCS information.
  2309  var vcsStatusCache par.ErrCache[string, vcs.Status]
  2310  
  2311  func appendBuildSetting(info *debug.BuildInfo, key, value string) {
  2312  	value = strings.ReplaceAll(value, "\n", " ") // make value safe
  2313  	info.Settings = append(info.Settings, debug.BuildSetting{Key: key, Value: value})
  2314  }
  2315  
  2316  // setBuildInfo gathers build information and sets it into
  2317  // p.Internal.BuildInfo, which will later be formatted as a string and embedded
  2318  // in the binary. setBuildInfo should only be called on a main package with no
  2319  // errors.
  2320  //
  2321  // This information can be retrieved using debug.ReadBuildInfo.
  2322  //
  2323  // Note that the GoVersion field is not set here to avoid encoding it twice.
  2324  // It is stored separately in the binary, mostly for historical reasons.
  2325  func (p *Package) setBuildInfo(ctx context.Context, autoVCS bool) {
  2326  	setPkgErrorf := func(format string, args ...any) {
  2327  		if p.Error == nil {
  2328  			p.Error = &PackageError{Err: fmt.Errorf(format, args...)}
  2329  			p.Incomplete = true
  2330  		}
  2331  	}
  2332  
  2333  	var debugModFromModinfo func(*modinfo.ModulePublic) *debug.Module
  2334  	debugModFromModinfo = func(mi *modinfo.ModulePublic) *debug.Module {
  2335  		version := mi.Version
  2336  		if version == "" {
  2337  			version = "(devel)"
  2338  		}
  2339  		dm := &debug.Module{
  2340  			Path:    mi.Path,
  2341  			Version: version,
  2342  		}
  2343  		if mi.Replace != nil {
  2344  			dm.Replace = debugModFromModinfo(mi.Replace)
  2345  		} else if mi.Version != "" && cfg.BuildMod != "vendor" {
  2346  			dm.Sum = modfetch.Sum(ctx, module.Version{Path: mi.Path, Version: mi.Version})
  2347  		}
  2348  		return dm
  2349  	}
  2350  
  2351  	var main debug.Module
  2352  	if p.Module != nil {
  2353  		main = *debugModFromModinfo(p.Module)
  2354  	}
  2355  
  2356  	visited := make(map[*Package]bool)
  2357  	mdeps := make(map[module.Version]*debug.Module)
  2358  	var q []*Package
  2359  	q = append(q, p.Internal.Imports...)
  2360  	for len(q) > 0 {
  2361  		p1 := q[0]
  2362  		q = q[1:]
  2363  		if visited[p1] {
  2364  			continue
  2365  		}
  2366  		visited[p1] = true
  2367  		if p1.Module != nil {
  2368  			m := module.Version{Path: p1.Module.Path, Version: p1.Module.Version}
  2369  			if p1.Module.Path != main.Path && mdeps[m] == nil {
  2370  				mdeps[m] = debugModFromModinfo(p1.Module)
  2371  			}
  2372  		}
  2373  		q = append(q, p1.Internal.Imports...)
  2374  	}
  2375  	sortedMods := make([]module.Version, 0, len(mdeps))
  2376  	for mod := range mdeps {
  2377  		sortedMods = append(sortedMods, mod)
  2378  	}
  2379  	gover.ModSort(sortedMods)
  2380  	deps := make([]*debug.Module, len(sortedMods))
  2381  	for i, mod := range sortedMods {
  2382  		deps[i] = mdeps[mod]
  2383  	}
  2384  
  2385  	pkgPath := p.ImportPath
  2386  	if p.Internal.CmdlineFiles {
  2387  		pkgPath = "command-line-arguments"
  2388  	}
  2389  	info := &debug.BuildInfo{
  2390  		Path: pkgPath,
  2391  		Main: main,
  2392  		Deps: deps,
  2393  	}
  2394  	appendSetting := func(key, value string) {
  2395  		appendBuildSetting(info, key, value)
  2396  	}
  2397  
  2398  	// Add command-line flags relevant to the build.
  2399  	// This is informational, not an exhaustive list.
  2400  	// Please keep the list sorted.
  2401  	if cfg.BuildASan {
  2402  		appendSetting("-asan", "true")
  2403  	}
  2404  	if BuildAsmflags.present {
  2405  		appendSetting("-asmflags", BuildAsmflags.String())
  2406  	}
  2407  	buildmode := cfg.BuildBuildmode
  2408  	if buildmode == "default" {
  2409  		if p.Name == "main" {
  2410  			buildmode = "exe"
  2411  		} else {
  2412  			buildmode = "archive"
  2413  		}
  2414  	}
  2415  	appendSetting("-buildmode", buildmode)
  2416  	appendSetting("-compiler", cfg.BuildContext.Compiler)
  2417  	if gccgoflags := BuildGccgoflags.String(); gccgoflags != "" && cfg.BuildContext.Compiler == "gccgo" {
  2418  		appendSetting("-gccgoflags", gccgoflags)
  2419  	}
  2420  	if gcflags := BuildGcflags.String(); gcflags != "" && cfg.BuildContext.Compiler == "gc" {
  2421  		appendSetting("-gcflags", gcflags)
  2422  	}
  2423  	if ldflags := BuildLdflags.String(); ldflags != "" {
  2424  		// https://go.dev/issue/52372: only include ldflags if -trimpath is not set,
  2425  		// since it can include system paths through various linker flags (notably
  2426  		// -extar, -extld, and -extldflags).
  2427  		//
  2428  		// TODO: since we control cmd/link, in theory we can parse ldflags to
  2429  		// determine whether they may refer to system paths. If we do that, we can
  2430  		// redact only those paths from the recorded -ldflags setting and still
  2431  		// record the system-independent parts of the flags.
  2432  		if !cfg.BuildTrimpath {
  2433  			appendSetting("-ldflags", ldflags)
  2434  		}
  2435  	}
  2436  	if cfg.BuildCover {
  2437  		appendSetting("-cover", "true")
  2438  	}
  2439  	if cfg.BuildMSan {
  2440  		appendSetting("-msan", "true")
  2441  	}
  2442  	// N.B. -pgo added later by setPGOProfilePath.
  2443  	if cfg.BuildRace {
  2444  		appendSetting("-race", "true")
  2445  	}
  2446  	if tags := cfg.BuildContext.BuildTags; len(tags) > 0 {
  2447  		appendSetting("-tags", strings.Join(tags, ","))
  2448  	}
  2449  	if cfg.BuildTrimpath {
  2450  		appendSetting("-trimpath", "true")
  2451  	}
  2452  	if p.DefaultGODEBUG != "" {
  2453  		appendSetting("DefaultGODEBUG", p.DefaultGODEBUG)
  2454  	}
  2455  	cgo := "0"
  2456  	if cfg.BuildContext.CgoEnabled {
  2457  		cgo = "1"
  2458  	}
  2459  	appendSetting("CGO_ENABLED", cgo)
  2460  	// https://go.dev/issue/52372: only include CGO flags if -trimpath is not set.
  2461  	// (If -trimpath is set, it is possible that these flags include system paths.)
  2462  	// If cgo is involved, reproducibility is already pretty well ruined anyway,
  2463  	// given that we aren't stamping header or library versions.
  2464  	//
  2465  	// TODO(bcmills): perhaps we could at least parse the flags and stamp the
  2466  	// subset of flags that are known not to be paths?
  2467  	if cfg.BuildContext.CgoEnabled && !cfg.BuildTrimpath {
  2468  		for _, name := range []string{"CGO_CFLAGS", "CGO_CPPFLAGS", "CGO_CXXFLAGS", "CGO_LDFLAGS"} {
  2469  			appendSetting(name, cfg.Getenv(name))
  2470  		}
  2471  	}
  2472  	appendSetting("GOARCH", cfg.BuildContext.GOARCH)
  2473  	if cfg.RawGOEXPERIMENT != "" {
  2474  		appendSetting("GOEXPERIMENT", cfg.RawGOEXPERIMENT)
  2475  	}
  2476  	if fips140.Enabled() {
  2477  		appendSetting("GOFIPS140", fips140.Version())
  2478  	}
  2479  	appendSetting("GOOS", cfg.BuildContext.GOOS)
  2480  	if key, val, _ := cfg.GetArchEnv(); key != "" && val != "" {
  2481  		appendSetting(key, val)
  2482  	}
  2483  
  2484  	// Add VCS status if all conditions are true:
  2485  	//
  2486  	// - -buildvcs is enabled.
  2487  	// - p is a non-test contained within a main module (there may be multiple
  2488  	//   main modules in a workspace, but local replacements don't count).
  2489  	// - Both the current directory and p's module's root directory are contained
  2490  	//   in the same local repository.
  2491  	// - We know the VCS commands needed to get the status.
  2492  	setVCSError := func(err error) {
  2493  		setPkgErrorf("error obtaining VCS status: %v\n\tUse -buildvcs=false to disable VCS stamping.", err)
  2494  	}
  2495  
  2496  	var repoDir string
  2497  	var vcsCmd *vcs.Cmd
  2498  	var err error
  2499  	const allowNesting = true
  2500  
  2501  	wantVCS := false
  2502  	switch cfg.BuildBuildvcs {
  2503  	case "true":
  2504  		wantVCS = true // Include VCS metadata even for tests if requested explicitly; see https://go.dev/issue/52648.
  2505  	case "auto":
  2506  		wantVCS = autoVCS && !p.IsTestOnly()
  2507  	case "false":
  2508  	default:
  2509  		panic(fmt.Sprintf("unexpected value for cfg.BuildBuildvcs: %q", cfg.BuildBuildvcs))
  2510  	}
  2511  
  2512  	if wantVCS && p.Module != nil && p.Module.Version == "" && !p.Standard {
  2513  		if p.Module.Path == "bootstrap" && cfg.GOROOT == os.Getenv("GOROOT_BOOTSTRAP") {
  2514  			// During bootstrapping, the bootstrap toolchain is built in module
  2515  			// "bootstrap" (instead of "std"), with GOROOT set to GOROOT_BOOTSTRAP
  2516  			// (so the bootstrap toolchain packages don't even appear to be in GOROOT).
  2517  			goto omitVCS
  2518  		}
  2519  		repoDir, vcsCmd, err = vcs.FromDir(base.Cwd(), "", allowNesting)
  2520  		if err != nil && !errors.Is(err, os.ErrNotExist) {
  2521  			setVCSError(err)
  2522  			return
  2523  		}
  2524  		if !str.HasFilePathPrefix(p.Module.Dir, repoDir) &&
  2525  			!str.HasFilePathPrefix(repoDir, p.Module.Dir) {
  2526  			// The module containing the main package does not overlap with the
  2527  			// repository containing the working directory. Don't include VCS info.
  2528  			// If the repo contains the module or vice versa, but they are not
  2529  			// the same directory, it's likely an error (see below).
  2530  			goto omitVCS
  2531  		}
  2532  		if cfg.BuildBuildvcs == "auto" && vcsCmd != nil && vcsCmd.Cmd != "" {
  2533  			if _, err := pathcache.LookPath(vcsCmd.Cmd); err != nil {
  2534  				// We fould a repository, but the required VCS tool is not present.
  2535  				// "-buildvcs=auto" means that we should silently drop the VCS metadata.
  2536  				goto omitVCS
  2537  			}
  2538  		}
  2539  	}
  2540  	if repoDir != "" && vcsCmd.Status != nil {
  2541  		// Check that the current directory, package, and module are in the same
  2542  		// repository. vcs.FromDir allows nested Git repositories, but nesting
  2543  		// is not allowed for other VCS tools. The current directory may be outside
  2544  		// p.Module.Dir when a workspace is used.
  2545  		pkgRepoDir, _, err := vcs.FromDir(p.Dir, "", allowNesting)
  2546  		if err != nil {
  2547  			setVCSError(err)
  2548  			return
  2549  		}
  2550  		if pkgRepoDir != repoDir {
  2551  			if cfg.BuildBuildvcs != "auto" {
  2552  				setVCSError(fmt.Errorf("main package is in repository %q but current directory is in repository %q", pkgRepoDir, repoDir))
  2553  				return
  2554  			}
  2555  			goto omitVCS
  2556  		}
  2557  		modRepoDir, _, err := vcs.FromDir(p.Module.Dir, "", allowNesting)
  2558  		if err != nil {
  2559  			setVCSError(err)
  2560  			return
  2561  		}
  2562  		if modRepoDir != repoDir {
  2563  			if cfg.BuildBuildvcs != "auto" {
  2564  				setVCSError(fmt.Errorf("main module is in repository %q but current directory is in repository %q", modRepoDir, repoDir))
  2565  				return
  2566  			}
  2567  			goto omitVCS
  2568  		}
  2569  
  2570  		st, err := vcsStatusCache.Do(repoDir, func() (vcs.Status, error) {
  2571  			return vcsCmd.Status(vcsCmd, repoDir)
  2572  		})
  2573  		if err != nil {
  2574  			setVCSError(err)
  2575  			return
  2576  		}
  2577  
  2578  		appendSetting("vcs", vcsCmd.Cmd)
  2579  		if st.Revision != "" {
  2580  			appendSetting("vcs.revision", st.Revision)
  2581  		}
  2582  		if !st.CommitTime.IsZero() {
  2583  			stamp := st.CommitTime.UTC().Format(time.RFC3339Nano)
  2584  			appendSetting("vcs.time", stamp)
  2585  		}
  2586  		appendSetting("vcs.modified", strconv.FormatBool(st.Uncommitted))
  2587  		// Determine the correct version of this module at the current revision and update the build metadata accordingly.
  2588  		rootModPath := goModPath(repoDir)
  2589  		// If no root module is found, skip embedding VCS data since we cannot determine the module path of the root.
  2590  		if rootModPath == "" {
  2591  			goto omitVCS
  2592  		}
  2593  		codeRoot, _, ok := module.SplitPathVersion(rootModPath)
  2594  		if !ok {
  2595  			goto omitVCS
  2596  		}
  2597  		repo := modfetch.LookupLocal(ctx, codeRoot, p.Module.Path, repoDir)
  2598  		revInfo, err := repo.Stat(ctx, st.Revision)
  2599  		if err != nil {
  2600  			goto omitVCS
  2601  		}
  2602  		vers := revInfo.Version
  2603  		if vers != "" {
  2604  			if st.Uncommitted {
  2605  				// SemVer build metadata is dot-separated https://semver.org/#spec-item-10
  2606  				if strings.HasSuffix(vers, "+incompatible") {
  2607  					vers += ".dirty"
  2608  				} else {
  2609  					vers += "+dirty"
  2610  				}
  2611  			}
  2612  			info.Main.Version = vers
  2613  		}
  2614  	}
  2615  omitVCS:
  2616  
  2617  	p.Internal.BuildInfo = info
  2618  }
  2619  
  2620  // SafeArg reports whether arg is a "safe" command-line argument,
  2621  // meaning that when it appears in a command-line, it probably
  2622  // doesn't have some special meaning other than its own name.
  2623  // Obviously args beginning with - are not safe (they look like flags).
  2624  // Less obviously, args beginning with @ are not safe (they look like
  2625  // GNU binutils flagfile specifiers, sometimes called "response files").
  2626  // To be conservative, we reject almost any arg beginning with non-alphanumeric ASCII.
  2627  // We accept leading . _ and / as likely in file system paths.
  2628  // There is a copy of this function in cmd/compile/internal/gc/noder.go.
  2629  func SafeArg(name string) bool {
  2630  	if name == "" {
  2631  		return false
  2632  	}
  2633  	c := name[0]
  2634  	return '0' <= c && c <= '9' || 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || c == '.' || c == '_' || c == '/' || c >= utf8.RuneSelf
  2635  }
  2636  
  2637  // LinkerDeps returns the list of linker-induced dependencies for main package p.
  2638  func LinkerDeps(p *Package) ([]string, error) {
  2639  	// Everything links runtime.
  2640  	deps := []string{"runtime"}
  2641  
  2642  	// External linking mode forces an import of runtime/cgo.
  2643  	if what := externalLinkingReason(p); what != "" && cfg.BuildContext.Compiler != "gccgo" {
  2644  		if !cfg.BuildContext.CgoEnabled {
  2645  			return nil, fmt.Errorf("%s requires external (cgo) linking, but cgo is not enabled", what)
  2646  		}
  2647  		deps = append(deps, "runtime/cgo")
  2648  	}
  2649  	// On ARM with GOARM=5, it forces an import of math, for soft floating point.
  2650  	if cfg.Goarch == "arm" {
  2651  		deps = append(deps, "math")
  2652  	}
  2653  	// Using the race detector forces an import of runtime/race.
  2654  	if cfg.BuildRace {
  2655  		deps = append(deps, "runtime/race")
  2656  	}
  2657  	// Using memory sanitizer forces an import of runtime/msan.
  2658  	if cfg.BuildMSan {
  2659  		deps = append(deps, "runtime/msan")
  2660  	}
  2661  	// Using address sanitizer forces an import of runtime/asan.
  2662  	if cfg.BuildASan {
  2663  		deps = append(deps, "runtime/asan")
  2664  	}
  2665  	// Building for coverage forces an import of runtime/coverage.
  2666  	if cfg.BuildCover {
  2667  		deps = append(deps, "runtime/coverage")
  2668  	}
  2669  
  2670  	return deps, nil
  2671  }
  2672  
  2673  // externalLinkingReason reports the reason external linking is required
  2674  // even for programs that do not use cgo, or the empty string if external
  2675  // linking is not required.
  2676  func externalLinkingReason(p *Package) (what string) {
  2677  	// Some targets must use external linking even inside GOROOT.
  2678  	if platform.MustLinkExternal(cfg.Goos, cfg.Goarch, false) {
  2679  		return cfg.Goos + "/" + cfg.Goarch
  2680  	}
  2681  
  2682  	// Some build modes always require external linking.
  2683  	switch cfg.BuildBuildmode {
  2684  	case "c-shared":
  2685  		if cfg.BuildContext.GOARCH == "wasm" {
  2686  			break
  2687  		}
  2688  		fallthrough
  2689  	case "plugin":
  2690  		return "-buildmode=" + cfg.BuildBuildmode
  2691  	}
  2692  
  2693  	// Using -linkshared always requires external linking.
  2694  	if cfg.BuildLinkshared {
  2695  		return "-linkshared"
  2696  	}
  2697  
  2698  	// Decide whether we are building a PIE,
  2699  	// bearing in mind that some systems default to PIE.
  2700  	isPIE := false
  2701  	if cfg.BuildBuildmode == "pie" {
  2702  		isPIE = true
  2703  	} else if cfg.BuildBuildmode == "default" && platform.DefaultPIE(cfg.BuildContext.GOOS, cfg.BuildContext.GOARCH, cfg.BuildRace) {
  2704  		isPIE = true
  2705  	}
  2706  	// If we are building a PIE, and we are on a system
  2707  	// that does not support PIE with internal linking mode,
  2708  	// then we must use external linking.
  2709  	if isPIE && !platform.InternalLinkPIESupported(cfg.BuildContext.GOOS, cfg.BuildContext.GOARCH) {
  2710  		if cfg.BuildBuildmode == "pie" {
  2711  			return "-buildmode=pie"
  2712  		}
  2713  		return "default PIE binary"
  2714  	}
  2715  
  2716  	// Using -ldflags=-linkmode=external forces external linking.
  2717  	// If there are multiple -linkmode options, the last one wins.
  2718  	if p != nil {
  2719  		ldflags := BuildLdflags.For(p)
  2720  		for i := len(ldflags) - 1; i >= 0; i-- {
  2721  			a := ldflags[i]
  2722  			if a == "-linkmode=external" ||
  2723  				a == "-linkmode" && i+1 < len(ldflags) && ldflags[i+1] == "external" {
  2724  				return a
  2725  			} else if a == "-linkmode=internal" ||
  2726  				a == "-linkmode" && i+1 < len(ldflags) && ldflags[i+1] == "internal" {
  2727  				return ""
  2728  			}
  2729  		}
  2730  	}
  2731  
  2732  	return ""
  2733  }
  2734  
  2735  // mkAbs rewrites list, which must be paths relative to p.Dir,
  2736  // into a sorted list of absolute paths. It edits list in place but for
  2737  // convenience also returns list back to its caller.
  2738  func (p *Package) mkAbs(list []string) []string {
  2739  	for i, f := range list {
  2740  		list[i] = filepath.Join(p.Dir, f)
  2741  	}
  2742  	sort.Strings(list)
  2743  	return list
  2744  }
  2745  
  2746  // InternalGoFiles returns the list of Go files being built for the package,
  2747  // using absolute paths.
  2748  func (p *Package) InternalGoFiles() []string {
  2749  	return p.mkAbs(str.StringList(p.GoFiles, p.CgoFiles, p.TestGoFiles))
  2750  }
  2751  
  2752  // InternalXGoFiles returns the list of Go files being built for the XTest package,
  2753  // using absolute paths.
  2754  func (p *Package) InternalXGoFiles() []string {
  2755  	return p.mkAbs(p.XTestGoFiles)
  2756  }
  2757  
  2758  // InternalAllGoFiles returns the list of all Go files possibly relevant for the package,
  2759  // using absolute paths. "Possibly relevant" means that files are not excluded
  2760  // due to build tags, but files with names beginning with . or _ are still excluded.
  2761  func (p *Package) InternalAllGoFiles() []string {
  2762  	return p.mkAbs(str.StringList(p.IgnoredGoFiles, p.GoFiles, p.CgoFiles, p.TestGoFiles, p.XTestGoFiles))
  2763  }
  2764  
  2765  // UsesSwig reports whether the package needs to run SWIG.
  2766  func (p *Package) UsesSwig() bool {
  2767  	return len(p.SwigFiles) > 0 || len(p.SwigCXXFiles) > 0
  2768  }
  2769  
  2770  // UsesCgo reports whether the package needs to run cgo
  2771  func (p *Package) UsesCgo() bool {
  2772  	return len(p.CgoFiles) > 0
  2773  }
  2774  
  2775  // PackageList returns the list of packages in the dag rooted at roots
  2776  // as visited in a depth-first post-order traversal.
  2777  func PackageList(roots []*Package) []*Package {
  2778  	seen := map[*Package]bool{}
  2779  	all := []*Package{}
  2780  	var walk func(*Package)
  2781  	walk = func(p *Package) {
  2782  		if seen[p] {
  2783  			return
  2784  		}
  2785  		seen[p] = true
  2786  		for _, p1 := range p.Internal.Imports {
  2787  			walk(p1)
  2788  		}
  2789  		all = append(all, p)
  2790  	}
  2791  	for _, root := range roots {
  2792  		walk(root)
  2793  	}
  2794  	return all
  2795  }
  2796  
  2797  // TestPackageList returns the list of packages in the dag rooted at roots
  2798  // as visited in a depth-first post-order traversal, including the test
  2799  // imports of the roots. This ignores errors in test packages.
  2800  func TestPackageList(ctx context.Context, opts PackageOpts, roots []*Package) []*Package {
  2801  	seen := map[*Package]bool{}
  2802  	all := []*Package{}
  2803  	var walk func(*Package)
  2804  	walk = func(p *Package) {
  2805  		if seen[p] {
  2806  			return
  2807  		}
  2808  		seen[p] = true
  2809  		for _, p1 := range p.Internal.Imports {
  2810  			walk(p1)
  2811  		}
  2812  		all = append(all, p)
  2813  	}
  2814  	walkTest := func(root *Package, path string) {
  2815  		var stk ImportStack
  2816  		p1, err := loadImport(ctx, opts, nil, path, root.Dir, root, &stk, root.Internal.Build.TestImportPos[path], ResolveImport)
  2817  		if err != nil && root.Error == nil {
  2818  			// Assign error importing the package to the importer.
  2819  			root.Error = err
  2820  			root.Incomplete = true
  2821  		}
  2822  		if p1.Error == nil {
  2823  			walk(p1)
  2824  		}
  2825  	}
  2826  	for _, root := range roots {
  2827  		walk(root)
  2828  		for _, path := range root.TestImports {
  2829  			walkTest(root, path)
  2830  		}
  2831  		for _, path := range root.XTestImports {
  2832  			walkTest(root, path)
  2833  		}
  2834  	}
  2835  	return all
  2836  }
  2837  
  2838  // LoadImportWithFlags loads the package with the given import path and
  2839  // sets tool flags on that package. This function is useful loading implicit
  2840  // dependencies (like sync/atomic for coverage).
  2841  // TODO(jayconrod): delete this function and set flags automatically
  2842  // in LoadImport instead.
  2843  func LoadImportWithFlags(path, srcDir string, parent *Package, stk *ImportStack, importPos []token.Position, mode int) (*Package, *PackageError) {
  2844  	p, err := loadImport(context.TODO(), PackageOpts{}, nil, path, srcDir, parent, stk, importPos, mode)
  2845  	setToolFlags(p)
  2846  	return p, err
  2847  }
  2848  
  2849  // LoadPackageWithFlags is the same as LoadImportWithFlags but without a parent.
  2850  // It's then guaranteed to not return an error
  2851  func LoadPackageWithFlags(path, srcDir string, stk *ImportStack, importPos []token.Position, mode int) *Package {
  2852  	p := LoadPackage(context.TODO(), PackageOpts{}, path, srcDir, stk, importPos, mode)
  2853  	setToolFlags(p)
  2854  	return p
  2855  }
  2856  
  2857  // PackageOpts control the behavior of PackagesAndErrors and other package
  2858  // loading functions.
  2859  type PackageOpts struct {
  2860  	// IgnoreImports controls whether we ignore explicit and implicit imports
  2861  	// when loading packages.  Implicit imports are added when supporting Cgo
  2862  	// or SWIG and when linking main packages.
  2863  	IgnoreImports bool
  2864  
  2865  	// ModResolveTests indicates whether calls to the module loader should also
  2866  	// resolve test dependencies of the requested packages.
  2867  	//
  2868  	// If ModResolveTests is true, then the module loader needs to resolve test
  2869  	// dependencies at the same time as packages; otherwise, the test dependencies
  2870  	// of those packages could be missing, and resolving those missing dependencies
  2871  	// could change the selected versions of modules that provide other packages.
  2872  	ModResolveTests bool
  2873  
  2874  	// MainOnly is true if the caller only wants to load main packages.
  2875  	// For a literal argument matching a non-main package, a stub may be returned
  2876  	// with an error. For a non-literal argument (with "..."), non-main packages
  2877  	// are not be matched, and their dependencies may not be loaded. A warning
  2878  	// may be printed for non-literal arguments that match no main packages.
  2879  	MainOnly bool
  2880  
  2881  	// AutoVCS controls whether we also load version-control metadata for main packages
  2882  	// when -buildvcs=auto (the default).
  2883  	AutoVCS bool
  2884  
  2885  	// SuppressBuildInfo is true if the caller does not need p.Stale, p.StaleReason, or p.Internal.BuildInfo
  2886  	// to be populated on the package.
  2887  	SuppressBuildInfo bool
  2888  
  2889  	// SuppressEmbedFiles is true if the caller does not need any embed files to be populated on the
  2890  	// package.
  2891  	SuppressEmbedFiles bool
  2892  }
  2893  
  2894  // PackagesAndErrors returns the packages named by the command line arguments
  2895  // 'patterns'. If a named package cannot be loaded, PackagesAndErrors returns
  2896  // a *Package with the Error field describing the failure. If errors are found
  2897  // loading imported packages, the DepsErrors field is set. The Incomplete field
  2898  // may be set as well.
  2899  //
  2900  // To obtain a flat list of packages, use PackageList.
  2901  // To report errors loading packages, use ReportPackageErrors.
  2902  func PackagesAndErrors(ctx context.Context, opts PackageOpts, patterns []string) []*Package {
  2903  	ctx, span := trace.StartSpan(ctx, "load.PackagesAndErrors")
  2904  	defer span.Done()
  2905  
  2906  	for _, p := range patterns {
  2907  		// Listing is only supported with all patterns referring to either:
  2908  		// - Files that are part of the same directory.
  2909  		// - Explicit package paths or patterns.
  2910  		if strings.HasSuffix(p, ".go") {
  2911  			// We need to test whether the path is an actual Go file and not a
  2912  			// package path or pattern ending in '.go' (see golang.org/issue/34653).
  2913  			if fi, err := fsys.Stat(p); err == nil && !fi.IsDir() {
  2914  				pkgs := []*Package{GoFilesPackage(ctx, opts, patterns)}
  2915  				setPGOProfilePath(pkgs)
  2916  				return pkgs
  2917  			}
  2918  		}
  2919  	}
  2920  
  2921  	var matches []*search.Match
  2922  	if modload.Init(); cfg.ModulesEnabled {
  2923  		modOpts := modload.PackageOpts{
  2924  			ResolveMissingImports: true,
  2925  			LoadTests:             opts.ModResolveTests,
  2926  			SilencePackageErrors:  true,
  2927  		}
  2928  		matches, _ = modload.LoadPackages(ctx, modOpts, patterns...)
  2929  	} else {
  2930  		matches = search.ImportPaths(patterns)
  2931  	}
  2932  
  2933  	var (
  2934  		pkgs    []*Package
  2935  		stk     ImportStack
  2936  		seenPkg = make(map[*Package]bool)
  2937  	)
  2938  
  2939  	pre := newPreload()
  2940  	defer pre.flush()
  2941  	pre.preloadMatches(ctx, opts, matches)
  2942  
  2943  	for _, m := range matches {
  2944  		for _, pkg := range m.Pkgs {
  2945  			if pkg == "" {
  2946  				panic(fmt.Sprintf("ImportPaths returned empty package for pattern %s", m.Pattern()))
  2947  			}
  2948  			mode := cmdlinePkg
  2949  			if m.IsLiteral() {
  2950  				// Note: do not set = m.IsLiteral unconditionally
  2951  				// because maybe we'll see p matching both
  2952  				// a literal and also a non-literal pattern.
  2953  				mode |= cmdlinePkgLiteral
  2954  			}
  2955  			p, perr := loadImport(ctx, opts, pre, pkg, base.Cwd(), nil, &stk, nil, mode)
  2956  			if perr != nil {
  2957  				base.Fatalf("internal error: loadImport of %q with nil parent returned an error", pkg)
  2958  			}
  2959  			p.Match = append(p.Match, m.Pattern())
  2960  			if seenPkg[p] {
  2961  				continue
  2962  			}
  2963  			seenPkg[p] = true
  2964  			pkgs = append(pkgs, p)
  2965  		}
  2966  
  2967  		if len(m.Errs) > 0 {
  2968  			// In addition to any packages that were actually resolved from the
  2969  			// pattern, there was some error in resolving the pattern itself.
  2970  			// Report it as a synthetic package.
  2971  			p := new(Package)
  2972  			p.ImportPath = m.Pattern()
  2973  			// Pass an empty ImportStack and nil importPos: the error arose from a pattern, not an import.
  2974  			var stk ImportStack
  2975  			var importPos []token.Position
  2976  			p.setLoadPackageDataError(m.Errs[0], m.Pattern(), &stk, importPos)
  2977  			p.Incomplete = true
  2978  			p.Match = append(p.Match, m.Pattern())
  2979  			p.Internal.CmdlinePkg = true
  2980  			if m.IsLiteral() {
  2981  				p.Internal.CmdlinePkgLiteral = true
  2982  			}
  2983  			pkgs = append(pkgs, p)
  2984  		}
  2985  	}
  2986  
  2987  	if opts.MainOnly {
  2988  		pkgs = mainPackagesOnly(pkgs, matches)
  2989  	}
  2990  
  2991  	// Now that CmdlinePkg is set correctly,
  2992  	// compute the effective flags for all loaded packages
  2993  	// (not just the ones matching the patterns but also
  2994  	// their dependencies).
  2995  	setToolFlags(pkgs...)
  2996  
  2997  	setPGOProfilePath(pkgs)
  2998  
  2999  	return pkgs
  3000  }
  3001  
  3002  // setPGOProfilePath sets the PGO profile path for pkgs.
  3003  // In -pgo=auto mode, it finds the default PGO profile.
  3004  func setPGOProfilePath(pkgs []*Package) {
  3005  	updateBuildInfo := func(p *Package, file string) {
  3006  		// Don't create BuildInfo for packages that didn't already have it.
  3007  		if p.Internal.BuildInfo == nil {
  3008  			return
  3009  		}
  3010  
  3011  		if cfg.BuildTrimpath {
  3012  			appendBuildSetting(p.Internal.BuildInfo, "-pgo", filepath.Base(file))
  3013  		} else {
  3014  			appendBuildSetting(p.Internal.BuildInfo, "-pgo", file)
  3015  		}
  3016  		// Adding -pgo breaks the sort order in BuildInfo.Settings. Restore it.
  3017  		slices.SortFunc(p.Internal.BuildInfo.Settings, func(x, y debug.BuildSetting) int {
  3018  			return strings.Compare(x.Key, y.Key)
  3019  		})
  3020  	}
  3021  
  3022  	switch cfg.BuildPGO {
  3023  	case "off":
  3024  		return
  3025  
  3026  	case "auto":
  3027  		// Locate PGO profiles from the main packages, and
  3028  		// attach the profile to the main package and its
  3029  		// dependencies.
  3030  		// If we're building multiple main packages, they may
  3031  		// have different profiles. We may need to split (unshare)
  3032  		// the dependency graph so they can attach different
  3033  		// profiles.
  3034  		for _, p := range pkgs {
  3035  			if p.Name != "main" {
  3036  				continue
  3037  			}
  3038  			pmain := p
  3039  			file := filepath.Join(pmain.Dir, "default.pgo")
  3040  			if _, err := os.Stat(file); err != nil {
  3041  				continue // no profile
  3042  			}
  3043  
  3044  			// Packages already visited. The value should replace
  3045  			// the key, as it may be a forked copy of the original
  3046  			// Package.
  3047  			visited := make(map[*Package]*Package)
  3048  			var split func(p *Package) *Package
  3049  			split = func(p *Package) *Package {
  3050  				if p1 := visited[p]; p1 != nil {
  3051  					return p1
  3052  				}
  3053  
  3054  				if len(pkgs) > 1 && p != pmain {
  3055  					// Make a copy, then attach profile.
  3056  					// No need to copy if there is only one root package (we can
  3057  					// attach profile directly in-place).
  3058  					// Also no need to copy the main package.
  3059  					if p.Internal.PGOProfile != "" {
  3060  						panic("setPGOProfilePath: already have profile")
  3061  					}
  3062  					p1 := new(Package)
  3063  					*p1 = *p
  3064  					// Unalias the Imports and Internal.Imports slices,
  3065  					// which we're going to modify. We don't copy other slices as
  3066  					// we don't change them.
  3067  					p1.Imports = slices.Clone(p.Imports)
  3068  					p1.Internal.Imports = slices.Clone(p.Internal.Imports)
  3069  					p1.Internal.ForMain = pmain.ImportPath
  3070  					visited[p] = p1
  3071  					p = p1
  3072  				} else {
  3073  					visited[p] = p
  3074  				}
  3075  				p.Internal.PGOProfile = file
  3076  				updateBuildInfo(p, file)
  3077  				// Recurse to dependencies.
  3078  				for i, pp := range p.Internal.Imports {
  3079  					p.Internal.Imports[i] = split(pp)
  3080  				}
  3081  				return p
  3082  			}
  3083  
  3084  			// Replace the package and imports with the PGO version.
  3085  			split(pmain)
  3086  		}
  3087  
  3088  	default:
  3089  		// Profile specified from the command line.
  3090  		// Make it absolute path, as the compiler runs on various directories.
  3091  		file, err := filepath.Abs(cfg.BuildPGO)
  3092  		if err != nil {
  3093  			base.Fatalf("fail to get absolute path of PGO file %s: %v", cfg.BuildPGO, err)
  3094  		}
  3095  
  3096  		for _, p := range PackageList(pkgs) {
  3097  			p.Internal.PGOProfile = file
  3098  			updateBuildInfo(p, file)
  3099  		}
  3100  	}
  3101  }
  3102  
  3103  // CheckPackageErrors prints errors encountered loading pkgs and their
  3104  // dependencies, then exits with a non-zero status if any errors were found.
  3105  func CheckPackageErrors(pkgs []*Package) {
  3106  	PackageErrors(pkgs, func(p *Package) {
  3107  		DefaultPrinter().Errorf(p, "%v", p.Error)
  3108  	})
  3109  	base.ExitIfErrors()
  3110  }
  3111  
  3112  // PackageErrors calls report for errors encountered loading pkgs and their dependencies.
  3113  func PackageErrors(pkgs []*Package, report func(*Package)) {
  3114  	var anyIncomplete, anyErrors bool
  3115  	for _, pkg := range pkgs {
  3116  		if pkg.Incomplete {
  3117  			anyIncomplete = true
  3118  		}
  3119  	}
  3120  	if anyIncomplete {
  3121  		all := PackageList(pkgs)
  3122  		for _, p := range all {
  3123  			if p.Error != nil {
  3124  				report(p)
  3125  				anyErrors = true
  3126  			}
  3127  		}
  3128  	}
  3129  	if anyErrors {
  3130  		return
  3131  	}
  3132  
  3133  	// Check for duplicate loads of the same package.
  3134  	// That should be impossible, but if it does happen then
  3135  	// we end up trying to build the same package twice,
  3136  	// usually in parallel overwriting the same files,
  3137  	// which doesn't work very well.
  3138  	seen := map[string]bool{}
  3139  	reported := map[string]bool{}
  3140  	for _, pkg := range PackageList(pkgs) {
  3141  		// -pgo=auto with multiple main packages can cause a package being
  3142  		// built multiple times (with different profiles).
  3143  		// We check that package import path + profile path is unique.
  3144  		key := pkg.ImportPath
  3145  		if pkg.Internal.PGOProfile != "" {
  3146  			key += " pgo:" + pkg.Internal.PGOProfile
  3147  		}
  3148  		if seen[key] && !reported[key] {
  3149  			reported[key] = true
  3150  			base.Errorf("internal error: duplicate loads of %s", pkg.ImportPath)
  3151  		}
  3152  		seen[key] = true
  3153  	}
  3154  	if len(reported) > 0 {
  3155  		base.ExitIfErrors()
  3156  	}
  3157  }
  3158  
  3159  // mainPackagesOnly filters out non-main packages matched only by arguments
  3160  // containing "..." and returns the remaining main packages.
  3161  //
  3162  // Packages with missing, invalid, or ambiguous names may be treated as
  3163  // possibly-main packages.
  3164  //
  3165  // mainPackagesOnly sets a non-main package's Error field and returns it if it
  3166  // is named by a literal argument.
  3167  //
  3168  // mainPackagesOnly prints warnings for non-literal arguments that only match
  3169  // non-main packages.
  3170  func mainPackagesOnly(pkgs []*Package, matches []*search.Match) []*Package {
  3171  	treatAsMain := map[string]bool{}
  3172  	for _, m := range matches {
  3173  		if m.IsLiteral() {
  3174  			for _, path := range m.Pkgs {
  3175  				treatAsMain[path] = true
  3176  			}
  3177  		}
  3178  	}
  3179  
  3180  	var mains []*Package
  3181  	for _, pkg := range pkgs {
  3182  		if pkg.Name == "main" || (pkg.Name == "" && pkg.Error != nil) {
  3183  			treatAsMain[pkg.ImportPath] = true
  3184  			mains = append(mains, pkg)
  3185  			continue
  3186  		}
  3187  
  3188  		if len(pkg.InvalidGoFiles) > 0 { // TODO(#45999): && pkg.Name == "", but currently go/build sets pkg.Name arbitrarily if it is ambiguous.
  3189  			// The package has (or may have) conflicting names, and we can't easily
  3190  			// tell whether one of them is "main". So assume that it could be, and
  3191  			// report an error for the package.
  3192  			treatAsMain[pkg.ImportPath] = true
  3193  		}
  3194  		if treatAsMain[pkg.ImportPath] {
  3195  			if pkg.Error == nil {
  3196  				pkg.Error = &PackageError{Err: &mainPackageError{importPath: pkg.ImportPath}}
  3197  				pkg.Incomplete = true
  3198  			}
  3199  			mains = append(mains, pkg)
  3200  		}
  3201  	}
  3202  
  3203  	for _, m := range matches {
  3204  		if m.IsLiteral() || len(m.Pkgs) == 0 {
  3205  			continue
  3206  		}
  3207  		foundMain := false
  3208  		for _, path := range m.Pkgs {
  3209  			if treatAsMain[path] {
  3210  				foundMain = true
  3211  				break
  3212  			}
  3213  		}
  3214  		if !foundMain {
  3215  			fmt.Fprintf(os.Stderr, "go: warning: %q matched only non-main packages\n", m.Pattern())
  3216  		}
  3217  	}
  3218  
  3219  	return mains
  3220  }
  3221  
  3222  type mainPackageError struct {
  3223  	importPath string
  3224  }
  3225  
  3226  func (e *mainPackageError) Error() string {
  3227  	return fmt.Sprintf("package %s is not a main package", e.importPath)
  3228  }
  3229  
  3230  func (e *mainPackageError) ImportPath() string {
  3231  	return e.importPath
  3232  }
  3233  
  3234  func setToolFlags(pkgs ...*Package) {
  3235  	for _, p := range PackageList(pkgs) {
  3236  		p.Internal.Asmflags = BuildAsmflags.For(p)
  3237  		p.Internal.Gcflags = BuildGcflags.For(p)
  3238  		p.Internal.Ldflags = BuildLdflags.For(p)
  3239  		p.Internal.Gccgoflags = BuildGccgoflags.For(p)
  3240  	}
  3241  }
  3242  
  3243  // GoFilesPackage creates a package for building a collection of Go files
  3244  // (typically named on the command line). The target is named p.a for
  3245  // package p or named after the first Go file for package main.
  3246  func GoFilesPackage(ctx context.Context, opts PackageOpts, gofiles []string) *Package {
  3247  	modload.Init()
  3248  
  3249  	for _, f := range gofiles {
  3250  		if !strings.HasSuffix(f, ".go") {
  3251  			pkg := new(Package)
  3252  			pkg.Internal.Local = true
  3253  			pkg.Internal.CmdlineFiles = true
  3254  			pkg.Name = f
  3255  			pkg.Error = &PackageError{
  3256  				Err: fmt.Errorf("named files must be .go files: %s", pkg.Name),
  3257  			}
  3258  			pkg.Incomplete = true
  3259  			return pkg
  3260  		}
  3261  	}
  3262  
  3263  	var stk ImportStack
  3264  	ctxt := cfg.BuildContext
  3265  	ctxt.UseAllFiles = true
  3266  
  3267  	// Synthesize fake "directory" that only shows the named files,
  3268  	// to make it look like this is a standard package or
  3269  	// command directory. So that local imports resolve
  3270  	// consistently, the files must all be in the same directory.
  3271  	var dirent []fs.FileInfo
  3272  	var dir string
  3273  	for _, file := range gofiles {
  3274  		fi, err := fsys.Stat(file)
  3275  		if err != nil {
  3276  			base.Fatalf("%s", err)
  3277  		}
  3278  		if fi.IsDir() {
  3279  			base.Fatalf("%s is a directory, should be a Go file", file)
  3280  		}
  3281  		dir1 := filepath.Dir(file)
  3282  		if dir == "" {
  3283  			dir = dir1
  3284  		} else if dir != dir1 {
  3285  			base.Fatalf("named files must all be in one directory; have %s and %s", dir, dir1)
  3286  		}
  3287  		dirent = append(dirent, fi)
  3288  	}
  3289  	ctxt.ReadDir = func(string) ([]fs.FileInfo, error) { return dirent, nil }
  3290  
  3291  	if cfg.ModulesEnabled {
  3292  		modload.ImportFromFiles(ctx, gofiles)
  3293  	}
  3294  
  3295  	var err error
  3296  	if dir == "" {
  3297  		dir = base.Cwd()
  3298  	}
  3299  	dir, err = filepath.Abs(dir)
  3300  	if err != nil {
  3301  		base.Fatalf("%s", err)
  3302  	}
  3303  
  3304  	bp, err := ctxt.ImportDir(dir, 0)
  3305  	pkg := new(Package)
  3306  	pkg.Internal.Local = true
  3307  	pkg.Internal.CmdlineFiles = true
  3308  	pkg.load(ctx, opts, "command-line-arguments", &stk, nil, bp, err)
  3309  	if !cfg.ModulesEnabled {
  3310  		pkg.Internal.LocalPrefix = dirToImportPath(dir)
  3311  	}
  3312  	pkg.ImportPath = "command-line-arguments"
  3313  	pkg.Target = ""
  3314  	pkg.Match = gofiles
  3315  
  3316  	if pkg.Name == "main" {
  3317  		exe := pkg.DefaultExecName() + cfg.ExeSuffix
  3318  
  3319  		if cfg.GOBIN != "" {
  3320  			pkg.Target = filepath.Join(cfg.GOBIN, exe)
  3321  		} else if cfg.ModulesEnabled {
  3322  			pkg.Target = filepath.Join(modload.BinDir(), exe)
  3323  		}
  3324  	}
  3325  
  3326  	if opts.MainOnly && pkg.Name != "main" && pkg.Error == nil {
  3327  		pkg.Error = &PackageError{Err: &mainPackageError{importPath: pkg.ImportPath}}
  3328  		pkg.Incomplete = true
  3329  	}
  3330  	setToolFlags(pkg)
  3331  
  3332  	return pkg
  3333  }
  3334  
  3335  // PackagesAndErrorsOutsideModule is like PackagesAndErrors but runs in
  3336  // module-aware mode and ignores the go.mod file in the current directory or any
  3337  // parent directory, if there is one. This is used in the implementation of 'go
  3338  // install pkg@version' and other commands that support similar forms.
  3339  //
  3340  // modload.ForceUseModules must be true, and modload.RootMode must be NoRoot
  3341  // before calling this function.
  3342  //
  3343  // PackagesAndErrorsOutsideModule imposes several constraints to avoid
  3344  // ambiguity. All arguments must have the same version suffix (not just a suffix
  3345  // that resolves to the same version). They must refer to packages in the same
  3346  // module, which must not be std or cmd. That module is not considered the main
  3347  // module, but its go.mod file (if it has one) must not contain directives that
  3348  // would cause it to be interpreted differently if it were the main module
  3349  // (replace, exclude).
  3350  func PackagesAndErrorsOutsideModule(ctx context.Context, opts PackageOpts, args []string) ([]*Package, error) {
  3351  	if !modload.ForceUseModules {
  3352  		panic("modload.ForceUseModules must be true")
  3353  	}
  3354  	if modload.RootMode != modload.NoRoot {
  3355  		panic("modload.RootMode must be NoRoot")
  3356  	}
  3357  
  3358  	// Check that the arguments satisfy syntactic constraints.
  3359  	var version string
  3360  	var firstPath string
  3361  	for _, arg := range args {
  3362  		if i := strings.Index(arg, "@"); i >= 0 {
  3363  			firstPath, version = arg[:i], arg[i+1:]
  3364  			if version == "" {
  3365  				return nil, fmt.Errorf("%s: version must not be empty", arg)
  3366  			}
  3367  			break
  3368  		}
  3369  	}
  3370  	patterns := make([]string, len(args))
  3371  	for i, arg := range args {
  3372  		p, found := strings.CutSuffix(arg, "@"+version)
  3373  		if !found {
  3374  			return nil, fmt.Errorf("%s: all arguments must refer to packages in the same module at the same version (@%s)", arg, version)
  3375  		}
  3376  		switch {
  3377  		case build.IsLocalImport(p):
  3378  			return nil, fmt.Errorf("%s: argument must be a package path, not a relative path", arg)
  3379  		case filepath.IsAbs(p):
  3380  			return nil, fmt.Errorf("%s: argument must be a package path, not an absolute path", arg)
  3381  		case search.IsMetaPackage(p):
  3382  			return nil, fmt.Errorf("%s: argument must be a package path, not a meta-package", arg)
  3383  		case pathpkg.Clean(p) != p:
  3384  			return nil, fmt.Errorf("%s: argument must be a clean package path", arg)
  3385  		case !strings.Contains(p, "...") && search.IsStandardImportPath(p) && modindex.IsStandardPackage(cfg.GOROOT, cfg.BuildContext.Compiler, p):
  3386  			return nil, fmt.Errorf("%s: argument must not be a package in the standard library", arg)
  3387  		default:
  3388  			patterns[i] = p
  3389  		}
  3390  	}
  3391  	patterns = search.CleanPatterns(patterns)
  3392  
  3393  	// Query the module providing the first argument, load its go.mod file, and
  3394  	// check that it doesn't contain directives that would cause it to be
  3395  	// interpreted differently if it were the main module.
  3396  	//
  3397  	// If multiple modules match the first argument, accept the longest match
  3398  	// (first result). It's possible this module won't provide packages named by
  3399  	// later arguments, and other modules would. Let's not try to be too
  3400  	// magical though.
  3401  	allowed := modload.CheckAllowed
  3402  	if modload.IsRevisionQuery(firstPath, version) {
  3403  		// Don't check for retractions if a specific revision is requested.
  3404  		allowed = nil
  3405  	}
  3406  	noneSelected := func(path string) (version string) { return "none" }
  3407  	qrs, err := modload.QueryPackages(ctx, patterns[0], version, noneSelected, allowed)
  3408  	if err != nil {
  3409  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3410  	}
  3411  	rootMod := qrs[0].Mod
  3412  	deprecation, err := modload.CheckDeprecation(ctx, rootMod)
  3413  	if err != nil {
  3414  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3415  	}
  3416  	if deprecation != "" {
  3417  		fmt.Fprintf(os.Stderr, "go: module %s is deprecated: %s\n", rootMod.Path, modload.ShortMessage(deprecation, ""))
  3418  	}
  3419  	data, err := modfetch.GoMod(ctx, rootMod.Path, rootMod.Version)
  3420  	if err != nil {
  3421  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3422  	}
  3423  	f, err := modfile.Parse("go.mod", data, nil)
  3424  	if err != nil {
  3425  		return nil, fmt.Errorf("%s (in %s): %w", args[0], rootMod, err)
  3426  	}
  3427  	directiveFmt := "%s (in %s):\n" +
  3428  		"\tThe go.mod file for the module providing named packages contains one or\n" +
  3429  		"\tmore %s directives. It must not contain directives that would cause\n" +
  3430  		"\tit to be interpreted differently than if it were the main module."
  3431  	if len(f.Replace) > 0 {
  3432  		return nil, fmt.Errorf(directiveFmt, args[0], rootMod, "replace")
  3433  	}
  3434  	if len(f.Exclude) > 0 {
  3435  		return nil, fmt.Errorf(directiveFmt, args[0], rootMod, "exclude")
  3436  	}
  3437  
  3438  	// Since we are in NoRoot mode, the build list initially contains only
  3439  	// the dummy command-line-arguments module. Add a requirement on the
  3440  	// module that provides the packages named on the command line.
  3441  	if _, err := modload.EditBuildList(ctx, nil, []module.Version{rootMod}); err != nil {
  3442  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3443  	}
  3444  
  3445  	// Load packages for all arguments.
  3446  	pkgs := PackagesAndErrors(ctx, opts, patterns)
  3447  
  3448  	// Check that named packages are all provided by the same module.
  3449  	for _, pkg := range pkgs {
  3450  		var pkgErr error
  3451  		if pkg.Module == nil {
  3452  			// Packages in std, cmd, and their vendored dependencies
  3453  			// don't have this field set.
  3454  			pkgErr = fmt.Errorf("package %s not provided by module %s", pkg.ImportPath, rootMod)
  3455  		} else if pkg.Module.Path != rootMod.Path || pkg.Module.Version != rootMod.Version {
  3456  			pkgErr = fmt.Errorf("package %s provided by module %s@%s\n\tAll packages must be provided by the same module (%s).", pkg.ImportPath, pkg.Module.Path, pkg.Module.Version, rootMod)
  3457  		}
  3458  		if pkgErr != nil && pkg.Error == nil {
  3459  			pkg.Error = &PackageError{Err: pkgErr}
  3460  			pkg.Incomplete = true
  3461  		}
  3462  	}
  3463  
  3464  	matchers := make([]func(string) bool, len(patterns))
  3465  	for i, p := range patterns {
  3466  		if strings.Contains(p, "...") {
  3467  			matchers[i] = pkgpattern.MatchPattern(p)
  3468  		}
  3469  	}
  3470  	return pkgs, nil
  3471  }
  3472  
  3473  // EnsureImport ensures that package p imports the named package.
  3474  func EnsureImport(p *Package, pkg string) {
  3475  	for _, d := range p.Internal.Imports {
  3476  		if d.Name == pkg {
  3477  			return
  3478  		}
  3479  	}
  3480  
  3481  	p1, err := LoadImportWithFlags(pkg, p.Dir, p, &ImportStack{}, nil, 0)
  3482  	if err != nil {
  3483  		base.Fatalf("load %s: %v", pkg, err)
  3484  	}
  3485  	if p1.Error != nil {
  3486  		base.Fatalf("load %s: %v", pkg, p1.Error)
  3487  	}
  3488  
  3489  	p.Internal.Imports = append(p.Internal.Imports, p1)
  3490  }
  3491  
  3492  // PrepareForCoverageBuild is a helper invoked for "go install
  3493  // -cover", "go run -cover", and "go build -cover" (but not used by
  3494  // "go test -cover"). It walks through the packages being built (and
  3495  // dependencies) and marks them for coverage instrumentation when
  3496  // appropriate, and possibly adding additional deps where needed.
  3497  func PrepareForCoverageBuild(pkgs []*Package) {
  3498  	var match []func(*Package) bool
  3499  
  3500  	matchMainModAndCommandLine := func(p *Package) bool {
  3501  		// note that p.Standard implies p.Module == nil below.
  3502  		return p.Internal.CmdlineFiles || p.Internal.CmdlinePkg || (p.Module != nil && p.Module.Main)
  3503  	}
  3504  
  3505  	if len(cfg.BuildCoverPkg) != 0 {
  3506  		// If -coverpkg has been specified, then we instrument only
  3507  		// the specific packages selected by the user-specified pattern(s).
  3508  		match = make([]func(*Package) bool, len(cfg.BuildCoverPkg))
  3509  		for i := range cfg.BuildCoverPkg {
  3510  			match[i] = MatchPackage(cfg.BuildCoverPkg[i], base.Cwd())
  3511  		}
  3512  	} else {
  3513  		// Without -coverpkg, instrument only packages in the main module
  3514  		// (if any), as well as packages/files specifically named on the
  3515  		// command line.
  3516  		match = []func(*Package) bool{matchMainModAndCommandLine}
  3517  	}
  3518  
  3519  	// Visit the packages being built or installed, along with all of
  3520  	// their dependencies, and mark them to be instrumented, taking
  3521  	// into account the matchers we've set up in the sequence above.
  3522  	SelectCoverPackages(PackageList(pkgs), match, "build")
  3523  }
  3524  
  3525  func SelectCoverPackages(roots []*Package, match []func(*Package) bool, op string) []*Package {
  3526  	var warntag string
  3527  	var includeMain bool
  3528  	switch op {
  3529  	case "build":
  3530  		warntag = "built"
  3531  		includeMain = true
  3532  	case "test":
  3533  		warntag = "tested"
  3534  	default:
  3535  		panic("internal error, bad mode passed to SelectCoverPackages")
  3536  	}
  3537  
  3538  	covered := []*Package{}
  3539  	matched := make([]bool, len(match))
  3540  	for _, p := range roots {
  3541  		haveMatch := false
  3542  		for i := range match {
  3543  			if match[i](p) {
  3544  				matched[i] = true
  3545  				haveMatch = true
  3546  			}
  3547  		}
  3548  		if !haveMatch {
  3549  			continue
  3550  		}
  3551  
  3552  		// There is nothing to cover in package unsafe; it comes from
  3553  		// the compiler.
  3554  		if p.ImportPath == "unsafe" {
  3555  			continue
  3556  		}
  3557  
  3558  		// A package which only has test files can't be imported as a
  3559  		// dependency, and at the moment we don't try to instrument it
  3560  		// for coverage. There isn't any technical reason why
  3561  		// *_test.go files couldn't be instrumented, but it probably
  3562  		// doesn't make much sense to lump together coverage metrics
  3563  		// (ex: percent stmts covered) of *_test.go files with
  3564  		// non-test Go code.
  3565  		if len(p.GoFiles)+len(p.CgoFiles) == 0 {
  3566  			continue
  3567  		}
  3568  
  3569  		// Silently ignore attempts to run coverage on sync/atomic
  3570  		// and/or internal/runtime/atomic when using atomic coverage
  3571  		// mode. Atomic coverage mode uses sync/atomic, so we can't
  3572  		// also do coverage on it.
  3573  		if cfg.BuildCoverMode == "atomic" && p.Standard &&
  3574  			(p.ImportPath == "sync/atomic" || p.ImportPath == "internal/runtime/atomic") {
  3575  			continue
  3576  		}
  3577  
  3578  		// If using the race detector, silently ignore attempts to run
  3579  		// coverage on the runtime packages. It will cause the race
  3580  		// detector to be invoked before it has been initialized. Note
  3581  		// the use of "regonly" instead of just ignoring the package
  3582  		// completely-- we do this due to the requirements of the
  3583  		// package ID numbering scheme. See the comment in
  3584  		// $GOROOT/src/internal/coverage/pkid.go dealing with
  3585  		// hard-coding of runtime package IDs.
  3586  		cmode := cfg.BuildCoverMode
  3587  		if cfg.BuildRace && p.Standard && objabi.LookupPkgSpecial(p.ImportPath).Runtime {
  3588  			cmode = "regonly"
  3589  		}
  3590  
  3591  		// If -coverpkg is in effect and for some reason we don't want
  3592  		// coverage data for the main package, make sure that we at
  3593  		// least process it for registration hooks.
  3594  		if includeMain && p.Name == "main" && !haveMatch {
  3595  			haveMatch = true
  3596  			cmode = "regonly"
  3597  		}
  3598  
  3599  		// Mark package for instrumentation.
  3600  		p.Internal.Cover.Mode = cmode
  3601  		covered = append(covered, p)
  3602  
  3603  		// Force import of sync/atomic into package if atomic mode.
  3604  		if cfg.BuildCoverMode == "atomic" {
  3605  			EnsureImport(p, "sync/atomic")
  3606  		}
  3607  	}
  3608  
  3609  	// Warn about -coverpkg arguments that are not actually used.
  3610  	for i := range cfg.BuildCoverPkg {
  3611  		if !matched[i] {
  3612  			fmt.Fprintf(os.Stderr, "warning: no packages being %s depend on matches for pattern %s\n", warntag, cfg.BuildCoverPkg[i])
  3613  		}
  3614  	}
  3615  
  3616  	return covered
  3617  }
  3618  

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