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