main.go

Documentation: cmd/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  //go:generate go test cmd/go -v -run=^TestDocsUpToDate$ -fixdocs
     6  
     7  package main
     8  
     9  import (
    10  	"context"
    11  	"flag"
    12  	"fmt"
    13  	"internal/buildcfg"
    14  	"log"
    15  	"os"
    16  	"path/filepath"
    17  	rtrace "runtime/trace"
    18  	"slices"
    19  	"strings"
    20  
    21  	"cmd/go/internal/base"
    22  	"cmd/go/internal/bug"
    23  	"cmd/go/internal/cfg"
    24  	"cmd/go/internal/clean"
    25  	"cmd/go/internal/doc"
    26  	"cmd/go/internal/envcmd"
    27  	"cmd/go/internal/fix"
    28  	"cmd/go/internal/fmtcmd"
    29  	"cmd/go/internal/generate"
    30  	"cmd/go/internal/help"
    31  	"cmd/go/internal/list"
    32  	"cmd/go/internal/modcmd"
    33  	"cmd/go/internal/modfetch"
    34  	"cmd/go/internal/modget"
    35  	"cmd/go/internal/modload"
    36  	"cmd/go/internal/run"
    37  	"cmd/go/internal/telemetrycmd"
    38  	"cmd/go/internal/telemetrystats"
    39  	"cmd/go/internal/test"
    40  	"cmd/go/internal/tool"
    41  	"cmd/go/internal/toolchain"
    42  	"cmd/go/internal/trace"
    43  	"cmd/go/internal/version"
    44  	"cmd/go/internal/vet"
    45  	"cmd/go/internal/work"
    46  	"cmd/go/internal/workcmd"
    47  	"cmd/internal/telemetry"
    48  	"cmd/internal/telemetry/counter"
    49  )
    50  
    51  func init() {
    52  	base.Go.Commands = []*base.Command{
    53  		bug.CmdBug,
    54  		work.CmdBuild,
    55  		clean.CmdClean,
    56  		doc.CmdDoc,
    57  		envcmd.CmdEnv,
    58  		fix.CmdFix,
    59  		fmtcmd.CmdFmt,
    60  		generate.CmdGenerate,
    61  		modget.CmdGet,
    62  		work.CmdInstall,
    63  		list.CmdList,
    64  		modcmd.CmdMod,
    65  		workcmd.CmdWork,
    66  		run.CmdRun,
    67  		telemetrycmd.CmdTelemetry,
    68  		test.CmdTest,
    69  		tool.CmdTool,
    70  		version.CmdVersion,
    71  		vet.CmdVet,
    72  
    73  		help.HelpBuildConstraint,
    74  		help.HelpBuildmode,
    75  		help.HelpC,
    76  		help.HelpCache,
    77  		help.HelpEnvironment,
    78  		help.HelpFileType,
    79  		modload.HelpGoMod,
    80  		help.HelpGopath,
    81  		modfetch.HelpGoproxy,
    82  		help.HelpImportPath,
    83  		modload.HelpModules,
    84  		modfetch.HelpModuleAuth,
    85  		help.HelpPackages,
    86  		modfetch.HelpPrivate,
    87  		test.HelpTestflag,
    88  		test.HelpTestfunc,
    89  		modget.HelpVCS,
    90  	}
    91  }
    92  
    93  var _ = go11tag
    94  
    95  var counterErrorsGOPATHEntryRelative = counter.New("go/errors:gopath-entry-relative")
    96  
    97  func main() {
    98  	log.SetFlags(0)
    99  	telemetry.MaybeChild() // Run in child mode if this is the telemetry sidecar child process.
   100  	counter.Open()         // Open the telemetry counter file so counters can be written to it.
   101  	handleChdirFlag()
   102  	toolchain.Select()
   103  
   104  	telemetry.MaybeParent() // Run the upload process. Opening the counter file is idempotent.
   105  	flag.Usage = base.Usage
   106  	flag.Parse()
   107  	counter.Inc("go/invocations")
   108  	counter.CountFlags("go/flag:", *flag.CommandLine)
   109  
   110  	args := flag.Args()
   111  	if len(args) < 1 {
   112  		base.Usage()
   113  	}
   114  
   115  	cfg.CmdName = args[0] // for error messages
   116  	if args[0] == "help" {
   117  		counter.Inc("go/subcommand:" + strings.Join(append([]string{"help"}, args[1:]...), "-"))
   118  		help.Help(os.Stdout, args[1:])
   119  		return
   120  	}
   121  
   122  	if cfg.GOROOT == "" {
   123  		fmt.Fprintf(os.Stderr, "go: cannot find GOROOT directory: 'go' binary is trimmed and GOROOT is not set\n")
   124  		os.Exit(2)
   125  	}
   126  	if fi, err := os.Stat(cfg.GOROOT); err != nil || !fi.IsDir() {
   127  		fmt.Fprintf(os.Stderr, "go: cannot find GOROOT directory: %v\n", cfg.GOROOT)
   128  		os.Exit(2)
   129  	}
   130  	switch strings.ToLower(cfg.GOROOT) {
   131  	case "/usr/local/go": // Location recommended for installation on Linux and Darwin and used by Mac installer.
   132  		counter.Inc("go/goroot:usr-local-go")
   133  	case "/usr/lib/go": // A typical location used by Linux package managers.
   134  		counter.Inc("go/goroot:usr-lib-go")
   135  	case "/usr/lib/golang": // Another typical location used by Linux package managers.
   136  		counter.Inc("go/goroot:usr-lib-golang")
   137  	case `c:\program files\go`: // Location used by Windows installer.
   138  		counter.Inc("go/goroot:program-files-go")
   139  	case `c:\program files (x86)\go`: // Location used by 386 Windows installer on amd64 platform.
   140  		counter.Inc("go/goroot:program-files-x86-go")
   141  	default:
   142  		counter.Inc("go/goroot:other")
   143  	}
   144  
   145  	// Diagnose common mistake: GOPATH==GOROOT.
   146  	// This setting is equivalent to not setting GOPATH at all,
   147  	// which is not what most people want when they do it.
   148  	if gopath := cfg.BuildContext.GOPATH; filepath.Clean(gopath) == filepath.Clean(cfg.GOROOT) {
   149  		fmt.Fprintf(os.Stderr, "warning: GOPATH set to GOROOT (%s) has no effect\n", gopath)
   150  	} else {
   151  		for _, p := range filepath.SplitList(gopath) {
   152  			// Some GOPATHs have empty directory elements - ignore them.
   153  			// See issue 21928 for details.
   154  			if p == "" {
   155  				continue
   156  			}
   157  			// Note: using HasPrefix instead of Contains because a ~ can appear
   158  			// in the middle of directory elements, such as /tmp/git-1.8.2~rc3
   159  			// or C:\PROGRA~1. Only ~ as a path prefix has meaning to the shell.
   160  			if strings.HasPrefix(p, "~") {
   161  				fmt.Fprintf(os.Stderr, "go: GOPATH entry cannot start with shell metacharacter '~': %q\n", p)
   162  				os.Exit(2)
   163  			}
   164  			if !filepath.IsAbs(p) {
   165  				if cfg.Getenv("GOPATH") == "" {
   166  					// We inferred $GOPATH from $HOME and did a bad job at it.
   167  					// Instead of dying, uninfer it.
   168  					cfg.BuildContext.GOPATH = ""
   169  				} else {
   170  					counterErrorsGOPATHEntryRelative.Inc()
   171  					fmt.Fprintf(os.Stderr, "go: GOPATH entry is relative; must be absolute path: %q.\nFor more details see: 'go help gopath'\n", p)
   172  					os.Exit(2)
   173  				}
   174  			}
   175  		}
   176  	}
   177  
   178  	cmd, used := lookupCmd(args)
   179  	cfg.CmdName = strings.Join(args[:used], " ")
   180  	if len(cmd.Commands) > 0 {
   181  		if used >= len(args) {
   182  			help.PrintUsage(os.Stderr, cmd)
   183  			base.SetExitStatus(2)
   184  			base.Exit()
   185  		}
   186  		if args[used] == "help" {
   187  			// Accept 'go mod help' and 'go mod help foo' for 'go help mod' and 'go help mod foo'.
   188  			counter.Inc("go/subcommand:" + strings.ReplaceAll(cfg.CmdName, " ", "-") + "-" + strings.Join(args[used:], "-"))
   189  			help.Help(os.Stdout, append(slices.Clip(args[:used]), args[used+1:]...))
   190  			base.Exit()
   191  		}
   192  		helpArg := ""
   193  		if used > 0 {
   194  			helpArg += " " + strings.Join(args[:used], " ")
   195  		}
   196  		cmdName := cfg.CmdName
   197  		if cmdName == "" {
   198  			cmdName = args[0]
   199  		}
   200  		counter.Inc("go/subcommand:unknown")
   201  		fmt.Fprintf(os.Stderr, "go %s: unknown command\nRun 'go help%s' for usage.\n", cmdName, helpArg)
   202  		base.SetExitStatus(2)
   203  		base.Exit()
   204  	}
   205  	// Increment a subcommand counter for the subcommand we're running.
   206  	// Don't increment the counter for the tool subcommand here: we'll
   207  	// increment in the tool subcommand's Run function because we need
   208  	// to do the flag processing in invoke first.
   209  	if cfg.CmdName != "tool" {
   210  		counter.Inc("go/subcommand:" + strings.ReplaceAll(cfg.CmdName, " ", "-"))
   211  	}
   212  	telemetrystats.Increment()
   213  	invoke(cmd, args[used-1:])
   214  	base.Exit()
   215  }
   216  
   217  // lookupCmd interprets the initial elements of args
   218  // to find a command to run (cmd.Runnable() == true)
   219  // or else a command group that ran out of arguments
   220  // or had an unknown subcommand (len(cmd.Commands) > 0).
   221  // It returns that command and the number of elements of args
   222  // that it took to arrive at that command.
   223  func lookupCmd(args []string) (cmd *base.Command, used int) {
   224  	cmd = base.Go
   225  	for used < len(args) {
   226  		c := cmd.Lookup(args[used])
   227  		if c == nil {
   228  			break
   229  		}
   230  		if c.Runnable() {
   231  			cmd = c
   232  			used++
   233  			break
   234  		}
   235  		if len(c.Commands) > 0 {
   236  			cmd = c
   237  			used++
   238  			if used >= len(args) || args[0] == "help" {
   239  				break
   240  			}
   241  			continue
   242  		}
   243  		// len(c.Commands) == 0 && !c.Runnable() => help text; stop at "help"
   244  		break
   245  	}
   246  	return cmd, used
   247  }
   248  
   249  func invoke(cmd *base.Command, args []string) {
   250  	// 'go env' handles checking the build config
   251  	if cmd != envcmd.CmdEnv {
   252  		buildcfg.Check()
   253  		if cfg.ExperimentErr != nil {
   254  			base.Fatal(cfg.ExperimentErr)
   255  		}
   256  	}
   257  
   258  	// Set environment (GOOS, GOARCH, etc) explicitly.
   259  	// In theory all the commands we invoke should have
   260  	// the same default computation of these as we do,
   261  	// but in practice there might be skew
   262  	// This makes sure we all agree.
   263  	cfg.OrigEnv = toolchain.FilterEnv(os.Environ())
   264  	cfg.CmdEnv = envcmd.MkEnv()
   265  	for _, env := range cfg.CmdEnv {
   266  		if os.Getenv(env.Name) != env.Value {
   267  			os.Setenv(env.Name, env.Value)
   268  		}
   269  	}
   270  
   271  	cmd.Flag.Usage = func() { cmd.Usage() }
   272  	if cmd.CustomFlags {
   273  		args = args[1:]
   274  	} else {
   275  		base.SetFromGOFLAGS(&cmd.Flag)
   276  		cmd.Flag.Parse(args[1:])
   277  		flagCounterPrefix := "go/" + strings.ReplaceAll(cfg.CmdName, " ", "-") + "/flag"
   278  		counter.CountFlags(flagCounterPrefix+":", cmd.Flag)
   279  		counter.CountFlagValue(flagCounterPrefix+"/", cmd.Flag, "buildmode")
   280  		args = cmd.Flag.Args()
   281  	}
   282  
   283  	if cfg.DebugRuntimeTrace != "" {
   284  		f, err := os.Create(cfg.DebugRuntimeTrace)
   285  		if err != nil {
   286  			base.Fatalf("creating trace file: %v", err)
   287  		}
   288  		if err := rtrace.Start(f); err != nil {
   289  			base.Fatalf("starting event trace: %v", err)
   290  		}
   291  		defer func() {
   292  			rtrace.Stop()
   293  			f.Close()
   294  		}()
   295  	}
   296  
   297  	ctx := maybeStartTrace(context.Background())
   298  	ctx, span := trace.StartSpan(ctx, fmt.Sprint("Running ", cmd.Name(), " command"))
   299  	cmd.Run(ctx, cmd, args)
   300  	span.Done()
   301  }
   302  
   303  func init() {
   304  	base.Usage = mainUsage
   305  }
   306  
   307  func mainUsage() {
   308  	help.PrintUsage(os.Stderr, base.Go)
   309  	os.Exit(2)
   310  }
   311  
   312  func maybeStartTrace(pctx context.Context) context.Context {
   313  	if cfg.DebugTrace == "" {
   314  		return pctx
   315  	}
   316  
   317  	ctx, close, err := trace.Start(pctx, cfg.DebugTrace)
   318  	if err != nil {
   319  		base.Fatalf("failed to start trace: %v", err)
   320  	}
   321  	base.AtExit(func() {
   322  		if err := close(); err != nil {
   323  			base.Fatalf("failed to stop trace: %v", err)
   324  		}
   325  	})
   326  
   327  	return ctx
   328  }
   329  
   330  // handleChdirFlag handles the -C flag before doing anything else.
   331  // The -C flag must be the first flag on the command line, to make it easy to find
   332  // even with commands that have custom flag parsing.
   333  // handleChdirFlag handles the flag by chdir'ing to the directory
   334  // and then removing that flag from the command line entirely.
   335  //
   336  // We have to handle the -C flag this way for two reasons:
   337  //
   338  //  1. Toolchain selection needs to be in the right directory to look for go.mod and go.work.
   339  //
   340  //  2. A toolchain switch later on reinvokes the new go command with the same arguments.
   341  //     The parent toolchain has already done the chdir; the child must not try to do it again.
   342  func handleChdirFlag() {
   343  	_, used := lookupCmd(os.Args[1:])
   344  	used++ // because of [1:]
   345  	if used >= len(os.Args) {
   346  		return
   347  	}
   348  
   349  	var dir string
   350  	switch a := os.Args[used]; {
   351  	default:
   352  		return
   353  
   354  	case a == "-C", a == "--C":
   355  		if used+1 >= len(os.Args) {
   356  			return
   357  		}
   358  		dir = os.Args[used+1]
   359  		os.Args = slices.Delete(os.Args, used, used+2)
   360  
   361  	case strings.HasPrefix(a, "-C="), strings.HasPrefix(a, "--C="):
   362  		_, dir, _ = strings.Cut(a, "=")
   363  		os.Args = slices.Delete(os.Args, used, used+1)
   364  	}
   365  	counter.Inc("go/flag:C")
   366  
   367  	if err := os.Chdir(dir); err != nil {
   368  		base.Fatalf("go: %v", err)
   369  	}
   370  }
   371
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