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