tool.go

Documentation: cmd/go/internal/tool

     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 tool implements the “go tool” command.
     6  package tool
     7  
     8  import (
     9  	"cmd/internal/telemetry/counter"
    10  	"context"
    11  	"encoding/json"
    12  	"flag"
    13  	"fmt"
    14  	"go/build"
    15  	"internal/platform"
    16  	"os"
    17  	"os/exec"
    18  	"os/signal"
    19  	"sort"
    20  	"strings"
    21  
    22  	"cmd/go/internal/base"
    23  	"cmd/go/internal/cfg"
    24  )
    25  
    26  var CmdTool = &base.Command{
    27  	Run:       runTool,
    28  	UsageLine: "go tool [-n] command [args...]",
    29  	Short:     "run specified go tool",
    30  	Long: `
    31  Tool runs the go tool command identified by the arguments.
    32  With no arguments it prints the list of known tools.
    33  
    34  The -n flag causes tool to print the command that would be
    35  executed but not execute it.
    36  
    37  For more about each tool command, see 'go doc cmd/<command>'.
    38  `,
    39  }
    40  
    41  var toolN bool
    42  
    43  // Return whether tool can be expected in the gccgo tool directory.
    44  // Other binaries could be in the same directory so don't
    45  // show those with the 'go tool' command.
    46  func isGccgoTool(tool string) bool {
    47  	switch tool {
    48  	case "cgo", "fix", "cover", "godoc", "vet":
    49  		return true
    50  	}
    51  	return false
    52  }
    53  
    54  func init() {
    55  	base.AddChdirFlag(&CmdTool.Flag)
    56  	CmdTool.Flag.BoolVar(&toolN, "n", false, "")
    57  }
    58  
    59  func runTool(ctx context.Context, cmd *base.Command, args []string) {
    60  	if len(args) == 0 {
    61  		counter.Inc("go/subcommand:tool")
    62  		listTools()
    63  		return
    64  	}
    65  	toolName := args[0]
    66  	// The tool name must be lower-case letters, numbers or underscores.
    67  	for _, c := range toolName {
    68  		switch {
    69  		case 'a' <= c && c <= 'z', '0' <= c && c <= '9', c == '_':
    70  		default:
    71  			fmt.Fprintf(os.Stderr, "go: bad tool name %q\n", toolName)
    72  			base.SetExitStatus(2)
    73  			return
    74  		}
    75  	}
    76  
    77  	toolPath, err := base.ToolPath(toolName)
    78  	if err != nil {
    79  		if toolName == "dist" && len(args) > 1 && args[1] == "list" {
    80  			// cmd/distpack removes the 'dist' tool from the toolchain to save space,
    81  			// since it is normally only used for building the toolchain in the first
    82  			// place. However, 'go tool dist list' is useful for listing all supported
    83  			// platforms.
    84  			//
    85  			// If the dist tool does not exist, impersonate this command.
    86  			if impersonateDistList(args[2:]) {
    87  				// If it becomes necessary, we could increment an additional counter to indicate
    88  				// that we're impersonating dist list if knowing that becomes important?
    89  				counter.Inc("go/subcommand:tool-dist")
    90  				return
    91  			}
    92  		}
    93  
    94  		counter.Inc("go/subcommand:tool-unknown")
    95  		// Emit the usual error for the missing tool.
    96  		_ = base.Tool(toolName)
    97  	} else {
    98  		// Increment a counter for the tool subcommand with the tool name.
    99  		counter.Inc("go/subcommand:tool-" + toolName)
   100  	}
   101  
   102  	if toolN {
   103  		cmd := toolPath
   104  		if len(args) > 1 {
   105  			cmd += " " + strings.Join(args[1:], " ")
   106  		}
   107  		fmt.Printf("%s\n", cmd)
   108  		return
   109  	}
   110  	args[0] = toolPath // in case the tool wants to re-exec itself, e.g. cmd/dist
   111  	toolCmd := &exec.Cmd{
   112  		Path:   toolPath,
   113  		Args:   args,
   114  		Stdin:  os.Stdin,
   115  		Stdout: os.Stdout,
   116  		Stderr: os.Stderr,
   117  	}
   118  	err = toolCmd.Start()
   119  	if err == nil {
   120  		c := make(chan os.Signal, 100)
   121  		signal.Notify(c)
   122  		go func() {
   123  			for sig := range c {
   124  				toolCmd.Process.Signal(sig)
   125  			}
   126  		}()
   127  		err = toolCmd.Wait()
   128  		signal.Stop(c)
   129  		close(c)
   130  	}
   131  	if err != nil {
   132  		// Only print about the exit status if the command
   133  		// didn't even run (not an ExitError) or it didn't exit cleanly
   134  		// or we're printing command lines too (-x mode).
   135  		// Assume if command exited cleanly (even with non-zero status)
   136  		// it printed any messages it wanted to print.
   137  		if e, ok := err.(*exec.ExitError); !ok || !e.Exited() || cfg.BuildX {
   138  			fmt.Fprintf(os.Stderr, "go tool %s: %s\n", toolName, err)
   139  		}
   140  		base.SetExitStatus(1)
   141  		return
   142  	}
   143  }
   144  
   145  // listTools prints a list of the available tools in the tools directory.
   146  func listTools() {
   147  	f, err := os.Open(build.ToolDir)
   148  	if err != nil {
   149  		fmt.Fprintf(os.Stderr, "go: no tool directory: %s\n", err)
   150  		base.SetExitStatus(2)
   151  		return
   152  	}
   153  	defer f.Close()
   154  	names, err := f.Readdirnames(-1)
   155  	if err != nil {
   156  		fmt.Fprintf(os.Stderr, "go: can't read tool directory: %s\n", err)
   157  		base.SetExitStatus(2)
   158  		return
   159  	}
   160  
   161  	sort.Strings(names)
   162  	for _, name := range names {
   163  		// Unify presentation by going to lower case.
   164  		// If it's windows, don't show the .exe suffix.
   165  		name = strings.TrimSuffix(strings.ToLower(name), cfg.ToolExeSuffix())
   166  
   167  		// The tool directory used by gccgo will have other binaries
   168  		// in addition to go tools. Only display go tools here.
   169  		if cfg.BuildToolchainName == "gccgo" && !isGccgoTool(name) {
   170  			continue
   171  		}
   172  		fmt.Println(name)
   173  	}
   174  }
   175  
   176  func impersonateDistList(args []string) (handled bool) {
   177  	fs := flag.NewFlagSet("go tool dist list", flag.ContinueOnError)
   178  	jsonFlag := fs.Bool("json", false, "produce JSON output")
   179  	brokenFlag := fs.Bool("broken", false, "include broken ports")
   180  
   181  	// The usage for 'go tool dist' claims that
   182  	// “All commands take -v flags to emit extra information”,
   183  	// but list -v appears not to have any effect.
   184  	_ = fs.Bool("v", false, "emit extra information")
   185  
   186  	if err := fs.Parse(args); err != nil || len(fs.Args()) > 0 {
   187  		// Unrecognized flag or argument.
   188  		// Force fallback to the real 'go tool dist'.
   189  		return false
   190  	}
   191  
   192  	if !*jsonFlag {
   193  		for _, p := range platform.List {
   194  			if !*brokenFlag && platform.Broken(p.GOOS, p.GOARCH) {
   195  				continue
   196  			}
   197  			fmt.Println(p)
   198  		}
   199  		return true
   200  	}
   201  
   202  	type jsonResult struct {
   203  		GOOS         string
   204  		GOARCH       string
   205  		CgoSupported bool
   206  		FirstClass   bool
   207  		Broken       bool `json:",omitempty"`
   208  	}
   209  
   210  	var results []jsonResult
   211  	for _, p := range platform.List {
   212  		broken := platform.Broken(p.GOOS, p.GOARCH)
   213  		if broken && !*brokenFlag {
   214  			continue
   215  		}
   216  		if *jsonFlag {
   217  			results = append(results, jsonResult{
   218  				GOOS:         p.GOOS,
   219  				GOARCH:       p.GOARCH,
   220  				CgoSupported: platform.CgoSupported(p.GOOS, p.GOARCH),
   221  				FirstClass:   platform.FirstClass(p.GOOS, p.GOARCH),
   222  				Broken:       broken,
   223  			})
   224  		}
   225  	}
   226  	out, err := json.MarshalIndent(results, "", "\t")
   227  	if err != nil {
   228  		return false
   229  	}
   230  
   231  	os.Stdout.Write(out)
   232  	return true
   233  }
   234
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