run.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 run implements the “go run” command.
     6  package run
     7  
     8  import (
     9  	"context"
    10  	"go/build"
    11  	"path/filepath"
    12  	"strings"
    13  
    14  	"cmd/go/internal/base"
    15  	"cmd/go/internal/cfg"
    16  	"cmd/go/internal/load"
    17  	"cmd/go/internal/modload"
    18  	"cmd/go/internal/str"
    19  	"cmd/go/internal/work"
    20  )
    21  
    22  var CmdRun = &base.Command{
    23  	UsageLine: "go run [build flags] [-exec xprog] package [arguments...]",
    24  	Short:     "compile and run Go program",
    25  	Long: `
    26  Run compiles and runs the named main Go package.
    27  Typically the package is specified as a list of .go source files from a single
    28  directory, but it may also be an import path, file system path, or pattern
    29  matching a single known package, as in 'go run .' or 'go run my/cmd'.
    30  
    31  If the package argument has a version suffix (like @latest or @v1.0.0),
    32  "go run" builds the program in module-aware mode, ignoring the go.mod file in
    33  the current directory or any parent directory, if there is one. This is useful
    34  for running programs without affecting the dependencies of the main module.
    35  
    36  If the package argument doesn't have a version suffix, "go run" may run in
    37  module-aware mode or GOPATH mode, depending on the GO111MODULE environment
    38  variable and the presence of a go.mod file. See 'go help modules' for details.
    39  If module-aware mode is enabled, "go run" runs in the context of the main
    40  module.
    41  
    42  By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
    43  If the -exec flag is given, 'go run' invokes the binary using xprog:
    44  	'xprog a.out arguments...'.
    45  If the -exec flag is not given, GOOS or GOARCH is different from the system
    46  default, and a program named go_$GOOS_$GOARCH_exec can be found
    47  on the current search path, 'go run' invokes the binary using that program,
    48  for example 'go_js_wasm_exec a.out arguments...'. This allows execution of
    49  cross-compiled programs when a simulator or other execution method is
    50  available.
    51  
    52  By default, 'go run' compiles the binary without generating the information
    53  used by debuggers, to reduce build time. To include debugger information in
    54  the binary, use 'go build'.
    55  
    56  The go command places $GOROOT/bin at the beginning of $PATH in the
    57  subprocess environment, so that subprocesses that execute 'go' commands
    58  use the same 'go' as their parent.
    59  
    60  The exit status of Run is not the exit status of the compiled binary.
    61  
    62  For more about build flags, see 'go help build'.
    63  For more about specifying packages, see 'go help packages'.
    64  
    65  See also: go build.
    66  	`,
    67  }
    68  
    69  func init() {
    70  	CmdRun.Run = runRun // break init loop
    71  
    72  	work.AddBuildFlags(CmdRun, work.DefaultBuildFlags)
    73  	work.AddCoverFlags(CmdRun, nil)
    74  	CmdRun.Flag.Var((*base.StringsFlag)(&work.ExecCmd), "exec", "")
    75  }
    76  
    77  func runRun(ctx context.Context, cmd *base.Command, args []string) {
    78  	moduleLoaderState := modload.NewState()
    79  	if shouldUseOutsideModuleMode(args) {
    80  		// Set global module flags for 'go run cmd@version'.
    81  		// This must be done before modload.Init, but we need to call work.BuildInit
    82  		// before loading packages, since it affects package locations, e.g.,
    83  		// for -race and -msan.
    84  		moduleLoaderState.ForceUseModules = true
    85  		moduleLoaderState.RootMode = modload.NoRoot
    86  		moduleLoaderState.AllowMissingModuleImports()
    87  		modload.Init(moduleLoaderState)
    88  	} else {
    89  		moduleLoaderState.InitWorkfile()
    90  	}
    91  
    92  	work.BuildInit(moduleLoaderState)
    93  	b := work.NewBuilder("", moduleLoaderState.VendorDirOrEmpty)
    94  	defer func() {
    95  		if err := b.Close(); err != nil {
    96  			base.Fatal(err)
    97  		}
    98  	}()
    99  
   100  	i := 0
   101  	for i < len(args) && strings.HasSuffix(args[i], ".go") {
   102  		i++
   103  	}
   104  	pkgOpts := load.PackageOpts{MainOnly: true}
   105  	var p *load.Package
   106  	if i > 0 {
   107  		files := args[:i]
   108  		for _, file := range files {
   109  			if strings.HasSuffix(file, "_test.go") {
   110  				// GoFilesPackage is going to assign this to TestGoFiles.
   111  				// Reject since it won't be part of the build.
   112  				base.Fatalf("go: cannot run *_test.go files (%s)", file)
   113  			}
   114  		}
   115  		p = load.GoFilesPackage(moduleLoaderState, ctx, pkgOpts, files)
   116  	} else if len(args) > 0 && !strings.HasPrefix(args[0], "-") {
   117  		arg := args[0]
   118  		var pkgs []*load.Package
   119  		if strings.Contains(arg, "@") && !build.IsLocalImport(arg) && !filepath.IsAbs(arg) {
   120  			var err error
   121  			pkgs, err = load.PackagesAndErrorsOutsideModule(moduleLoaderState, ctx, pkgOpts, args[:1])
   122  			if err != nil {
   123  				base.Fatal(err)
   124  			}
   125  		} else {
   126  			pkgs = load.PackagesAndErrors(moduleLoaderState, ctx, pkgOpts, args[:1])
   127  		}
   128  
   129  		if len(pkgs) == 0 {
   130  			base.Fatalf("go: no packages loaded from %s", arg)
   131  		}
   132  		if len(pkgs) > 1 {
   133  			names := make([]string, 0, len(pkgs))
   134  			for _, p := range pkgs {
   135  				names = append(names, p.ImportPath)
   136  			}
   137  			base.Fatalf("go: pattern %s matches multiple packages:\n\t%s", arg, strings.Join(names, "\n\t"))
   138  		}
   139  		p = pkgs[0]
   140  		i++
   141  	} else {
   142  		base.Fatalf("go: no go files listed")
   143  	}
   144  	cmdArgs := args[i:]
   145  	load.CheckPackageErrors([]*load.Package{p})
   146  
   147  	if cfg.BuildCover {
   148  		load.PrepareForCoverageBuild(moduleLoaderState, []*load.Package{p})
   149  	}
   150  
   151  	p.Internal.OmitDebug = true
   152  	p.Target = "" // must build - not up to date
   153  	if p.Internal.CmdlineFiles {
   154  		//set executable name if go file is given as cmd-argument
   155  		var src string
   156  		if len(p.GoFiles) > 0 {
   157  			src = p.GoFiles[0]
   158  		} else if len(p.CgoFiles) > 0 {
   159  			src = p.CgoFiles[0]
   160  		} else {
   161  			// this case could only happen if the provided source uses cgo
   162  			// while cgo is disabled.
   163  			hint := ""
   164  			if !cfg.BuildContext.CgoEnabled {
   165  				hint = " (cgo is disabled)"
   166  			}
   167  			base.Fatalf("go: no suitable source files%s", hint)
   168  		}
   169  		p.Internal.ExeName = src[:len(src)-len(".go")]
   170  	} else {
   171  		p.Internal.ExeName = p.DefaultExecName()
   172  	}
   173  
   174  	a1 := b.LinkAction(moduleLoaderState, work.ModeBuild, work.ModeBuild, p)
   175  	a1.CacheExecutable = true
   176  	a := &work.Action{Mode: "go run", Actor: work.ActorFunc(buildRunProgram), Args: cmdArgs, Deps: []*work.Action{a1}}
   177  	b.Do(ctx, a)
   178  }
   179  
   180  // shouldUseOutsideModuleMode returns whether 'go run' will load packages in
   181  // module-aware mode, ignoring the go.mod file in the current directory. It
   182  // returns true if the first argument contains "@", does not begin with "-"
   183  // (resembling a flag) or end with ".go" (a file). The argument must not be a
   184  // local or absolute file path.
   185  //
   186  // These rules are slightly different than other commands. Whether or not
   187  // 'go run' uses this mode, it interprets arguments ending with ".go" as files
   188  // and uses arguments up to the last ".go" argument to comprise the package.
   189  // If there are no ".go" arguments, only the first argument is interpreted
   190  // as a package path, since there can be only one package.
   191  func shouldUseOutsideModuleMode(args []string) bool {
   192  	// NOTE: "@" not allowed in import paths, but it is allowed in non-canonical
   193  	// versions.
   194  	return len(args) > 0 &&
   195  		!strings.HasSuffix(args[0], ".go") &&
   196  		!strings.HasPrefix(args[0], "-") &&
   197  		strings.Contains(args[0], "@") &&
   198  		!build.IsLocalImport(args[0]) &&
   199  		!filepath.IsAbs(args[0])
   200  }
   201  
   202  // buildRunProgram is the action for running a binary that has already
   203  // been compiled. We ignore exit status.
   204  func buildRunProgram(b *work.Builder, ctx context.Context, a *work.Action) error {
   205  	cmdline := str.StringList(work.FindExecCmd(), a.Deps[0].BuiltTarget(), a.Args)
   206  	if cfg.BuildN || cfg.BuildX {
   207  		b.Shell(a).ShowCmd("", "%s", strings.Join(cmdline, " "))
   208  		if cfg.BuildN {
   209  			return nil
   210  		}
   211  	}
   212  
   213  	base.RunStdin(cmdline)
   214  	return nil
   215  }
   216
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