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  	if cfg.Experiment != nil && cfg.Experiment.CoverageRedesign {
    70  		work.AddCoverFlags(CmdRun, nil)
    71  	}
    72  	CmdRun.Flag.Var((*base.StringsFlag)(&work.ExecCmd), "exec", "")
    73  }
    74  
    75  func runRun(ctx context.Context, cmd *base.Command, args []string) {
    76  	if shouldUseOutsideModuleMode(args) {
    77  		// Set global module flags for 'go run cmd@version'.
    78  		// This must be done before modload.Init, but we need to call work.BuildInit
    79  		// before loading packages, since it affects package locations, e.g.,
    80  		// for -race and -msan.
    81  		modload.ForceUseModules = true
    82  		modload.RootMode = modload.NoRoot
    83  		modload.AllowMissingModuleImports()
    84  		modload.Init()
    85  	} else {
    86  		modload.InitWorkfile()
    87  	}
    88  
    89  	work.BuildInit()
    90  	b := work.NewBuilder("")
    91  	defer func() {
    92  		if err := b.Close(); err != nil {
    93  			base.Fatal(err)
    94  		}
    95  	}()
    96  
    97  	i := 0
    98  	for i < len(args) && strings.HasSuffix(args[i], ".go") {
    99  		i++
   100  	}
   101  	pkgOpts := load.PackageOpts{MainOnly: true}
   102  	var p *load.Package
   103  	if i > 0 {
   104  		files := args[:i]
   105  		for _, file := range files {
   106  			if strings.HasSuffix(file, "_test.go") {
   107  				// GoFilesPackage is going to assign this to TestGoFiles.
   108  				// Reject since it won't be part of the build.
   109  				base.Fatalf("go: cannot run *_test.go files (%s)", file)
   110  			}
   111  		}
   112  		p = load.GoFilesPackage(ctx, pkgOpts, files)
   113  	} else if len(args) > 0 && !strings.HasPrefix(args[0], "-") {
   114  		arg := args[0]
   115  		var pkgs []*load.Package
   116  		if strings.Contains(arg, "@") && !build.IsLocalImport(arg) && !filepath.IsAbs(arg) {
   117  			var err error
   118  			pkgs, err = load.PackagesAndErrorsOutsideModule(ctx, pkgOpts, args[:1])
   119  			if err != nil {
   120  				base.Fatal(err)
   121  			}
   122  		} else {
   123  			pkgs = load.PackagesAndErrors(ctx, pkgOpts, args[:1])
   124  		}
   125  
   126  		if len(pkgs) == 0 {
   127  			base.Fatalf("go: no packages loaded from %s", arg)
   128  		}
   129  		if len(pkgs) > 1 {
   130  			names := make([]string, 0, len(pkgs))
   131  			for _, p := range pkgs {
   132  				names = append(names, p.ImportPath)
   133  			}
   134  			base.Fatalf("go: pattern %s matches multiple packages:\n\t%s", arg, strings.Join(names, "\n\t"))
   135  		}
   136  		p = pkgs[0]
   137  		i++
   138  	} else {
   139  		base.Fatalf("go: no go files listed")
   140  	}
   141  	cmdArgs := args[i:]
   142  	load.CheckPackageErrors([]*load.Package{p})
   143  
   144  	if cfg.Experiment.CoverageRedesign && cfg.BuildCover {
   145  		load.PrepareForCoverageBuild([]*load.Package{p})
   146  	}
   147  
   148  	p.Internal.OmitDebug = true
   149  	p.Target = "" // must build - not up to date
   150  	if p.Internal.CmdlineFiles {
   151  		//set executable name if go file is given as cmd-argument
   152  		var src string
   153  		if len(p.GoFiles) > 0 {
   154  			src = p.GoFiles[0]
   155  		} else if len(p.CgoFiles) > 0 {
   156  			src = p.CgoFiles[0]
   157  		} else {
   158  			// this case could only happen if the provided source uses cgo
   159  			// while cgo is disabled.
   160  			hint := ""
   161  			if !cfg.BuildContext.CgoEnabled {
   162  				hint = " (cgo is disabled)"
   163  			}
   164  			base.Fatalf("go: no suitable source files%s", hint)
   165  		}
   166  		p.Internal.ExeName = src[:len(src)-len(".go")]
   167  	} else {
   168  		p.Internal.ExeName = p.DefaultExecName()
   169  	}
   170  
   171  	a1 := b.LinkAction(work.ModeBuild, work.ModeBuild, p)
   172  	a1.CacheExecutable = true
   173  	a := &work.Action{Mode: "go run", Actor: work.ActorFunc(buildRunProgram), Args: cmdArgs, Deps: []*work.Action{a1}}
   174  	b.Do(ctx, a)
   175  }
   176  
   177  // shouldUseOutsideModuleMode returns whether 'go run' will load packages in
   178  // module-aware mode, ignoring the go.mod file in the current directory. It
   179  // returns true if the first argument contains "@", does not begin with "-"
   180  // (resembling a flag) or end with ".go" (a file). The argument must not be a
   181  // local or absolute file path.
   182  //
   183  // These rules are slightly different than other commands. Whether or not
   184  // 'go run' uses this mode, it interprets arguments ending with ".go" as files
   185  // and uses arguments up to the last ".go" argument to comprise the package.
   186  // If there are no ".go" arguments, only the first argument is interpreted
   187  // as a package path, since there can be only one package.
   188  func shouldUseOutsideModuleMode(args []string) bool {
   189  	// NOTE: "@" not allowed in import paths, but it is allowed in non-canonical
   190  	// versions.
   191  	return len(args) > 0 &&
   192  		!strings.HasSuffix(args[0], ".go") &&
   193  		!strings.HasPrefix(args[0], "-") &&
   194  		strings.Contains(args[0], "@") &&
   195  		!build.IsLocalImport(args[0]) &&
   196  		!filepath.IsAbs(args[0])
   197  }
   198  
   199  // buildRunProgram is the action for running a binary that has already
   200  // been compiled. We ignore exit status.
   201  func buildRunProgram(b *work.Builder, ctx context.Context, a *work.Action) error {
   202  	cmdline := str.StringList(work.FindExecCmd(), a.Deps[0].BuiltTarget(), a.Args)
   203  	if cfg.BuildN || cfg.BuildX {
   204  		b.Shell(a).ShowCmd("", "%s", strings.Join(cmdline, " "))
   205  		if cfg.BuildN {
   206  			return nil
   207  		}
   208  	}
   209  
   210  	base.RunStdin(cmdline)
   211  	return nil
   212  }
   213
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