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 exit status of Run is not the exit status of the compiled binary.
    57  
    58  For more about build flags, see 'go help build'.
    59  For more about specifying packages, see 'go help packages'.
    60  
    61  See also: go build.
    62  	`,
    63  }
    64  
    65  func init() {
    66  	CmdRun.Run = runRun // break init loop
    67  
    68  	work.AddBuildFlags(CmdRun, work.DefaultBuildFlags)
    69  	work.AddCoverFlags(CmdRun, nil)
    70  	CmdRun.Flag.Var((*base.StringsFlag)(&work.ExecCmd), "exec", "")
    71  }
    72  
    73  func runRun(ctx context.Context, cmd *base.Command, args []string) {
    74  	if shouldUseOutsideModuleMode(args) {
    75  		// Set global module flags for 'go run cmd@version'.
    76  		// This must be done before modload.Init, but we need to call work.BuildInit
    77  		// before loading packages, since it affects package locations, e.g.,
    78  		// for -race and -msan.
    79  		modload.ForceUseModules = true
    80  		modload.RootMode = modload.NoRoot
    81  		modload.AllowMissingModuleImports()
    82  		modload.Init()
    83  	} else {
    84  		modload.InitWorkfile()
    85  	}
    86  
    87  	work.BuildInit()
    88  	b := work.NewBuilder("")
    89  	defer func() {
    90  		if err := b.Close(); err != nil {
    91  			base.Fatal(err)
    92  		}
    93  	}()
    94  
    95  	i := 0
    96  	for i < len(args) && strings.HasSuffix(args[i], ".go") {
    97  		i++
    98  	}
    99  	pkgOpts := load.PackageOpts{MainOnly: true}
   100  	var p *load.Package
   101  	if i > 0 {
   102  		files := args[:i]
   103  		for _, file := range files {
   104  			if strings.HasSuffix(file, "_test.go") {
   105  				// GoFilesPackage is going to assign this to TestGoFiles.
   106  				// Reject since it won't be part of the build.
   107  				base.Fatalf("go: cannot run *_test.go files (%s)", file)
   108  			}
   109  		}
   110  		p = load.GoFilesPackage(ctx, pkgOpts, files)
   111  	} else if len(args) > 0 && !strings.HasPrefix(args[0], "-") {
   112  		arg := args[0]
   113  		var pkgs []*load.Package
   114  		if strings.Contains(arg, "@") && !build.IsLocalImport(arg) && !filepath.IsAbs(arg) {
   115  			var err error
   116  			pkgs, err = load.PackagesAndErrorsOutsideModule(ctx, pkgOpts, args[:1])
   117  			if err != nil {
   118  				base.Fatal(err)
   119  			}
   120  		} else {
   121  			pkgs = load.PackagesAndErrors(ctx, pkgOpts, args[:1])
   122  		}
   123  
   124  		if len(pkgs) == 0 {
   125  			base.Fatalf("go: no packages loaded from %s", arg)
   126  		}
   127  		if len(pkgs) > 1 {
   128  			names := make([]string, 0, len(pkgs))
   129  			for _, p := range pkgs {
   130  				names = append(names, p.ImportPath)
   131  			}
   132  			base.Fatalf("go: pattern %s matches multiple packages:\n\t%s", arg, strings.Join(names, "\n\t"))
   133  		}
   134  		p = pkgs[0]
   135  		i++
   136  	} else {
   137  		base.Fatalf("go: no go files listed")
   138  	}
   139  	cmdArgs := args[i:]
   140  	load.CheckPackageErrors([]*load.Package{p})
   141  
   142  	if cfg.BuildCover {
   143  		load.PrepareForCoverageBuild([]*load.Package{p})
   144  	}
   145  
   146  	p.Internal.OmitDebug = true
   147  	p.Target = "" // must build - not up to date
   148  	if p.Internal.CmdlineFiles {
   149  		//set executable name if go file is given as cmd-argument
   150  		var src string
   151  		if len(p.GoFiles) > 0 {
   152  			src = p.GoFiles[0]
   153  		} else if len(p.CgoFiles) > 0 {
   154  			src = p.CgoFiles[0]
   155  		} else {
   156  			// this case could only happen if the provided source uses cgo
   157  			// while cgo is disabled.
   158  			hint := ""
   159  			if !cfg.BuildContext.CgoEnabled {
   160  				hint = " (cgo is disabled)"
   161  			}
   162  			base.Fatalf("go: no suitable source files%s", hint)
   163  		}
   164  		p.Internal.ExeName = src[:len(src)-len(".go")]
   165  	} else {
   166  		p.Internal.ExeName = p.DefaultExecName()
   167  	}
   168  
   169  	a1 := b.LinkAction(work.ModeBuild, work.ModeBuild, p)
   170  	a1.CacheExecutable = true
   171  	a := &work.Action{Mode: "go run", Actor: work.ActorFunc(buildRunProgram), Args: cmdArgs, Deps: []*work.Action{a1}}
   172  	b.Do(ctx, a)
   173  }
   174  
   175  // shouldUseOutsideModuleMode returns whether 'go run' will load packages in
   176  // module-aware mode, ignoring the go.mod file in the current directory. It
   177  // returns true if the first argument contains "@", does not begin with "-"
   178  // (resembling a flag) or end with ".go" (a file). The argument must not be a
   179  // local or absolute file path.
   180  //
   181  // These rules are slightly different than other commands. Whether or not
   182  // 'go run' uses this mode, it interprets arguments ending with ".go" as files
   183  // and uses arguments up to the last ".go" argument to comprise the package.
   184  // If there are no ".go" arguments, only the first argument is interpreted
   185  // as a package path, since there can be only one package.
   186  func shouldUseOutsideModuleMode(args []string) bool {
   187  	// NOTE: "@" not allowed in import paths, but it is allowed in non-canonical
   188  	// versions.
   189  	return len(args) > 0 &&
   190  		!strings.HasSuffix(args[0], ".go") &&
   191  		!strings.HasPrefix(args[0], "-") &&
   192  		strings.Contains(args[0], "@") &&
   193  		!build.IsLocalImport(args[0]) &&
   194  		!filepath.IsAbs(args[0])
   195  }
   196  
   197  // buildRunProgram is the action for running a binary that has already
   198  // been compiled. We ignore exit status.
   199  func buildRunProgram(b *work.Builder, ctx context.Context, a *work.Action) error {
   200  	cmdline := str.StringList(work.FindExecCmd(), a.Deps[0].BuiltTarget(), a.Args)
   201  	if cfg.BuildN || cfg.BuildX {
   202  		b.Shell(a).ShowCmd("", "%s", strings.Join(cmdline, " "))
   203  		if cfg.BuildN {
   204  			return nil
   205  		}
   206  	}
   207  
   208  	base.RunStdin(cmdline)
   209  	return nil
   210  }
   211
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