1 files changed, 125 insertions, 0 deletions
diff --git a/src/cmd/go/tool.go b/src/cmd/go/tool.go
new file mode 100644
index 000000000..cb463a2e7
--- /dev/null
+++ b/src/cmd/go/tool.go
@@ -0,0 +1,125 @@
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"go/build"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"sort"
+	"strings"
+)
+
+var cmdTool = &Command{
+	Run:       runTool,
+	UsageLine: "tool [-n] command [args...]",
+	Short:     "run specified go tool",
+	Long: `
+Tool runs the go tool command identified by the arguments.
+With no arguments it prints the list of known tools.
+
+The -n flag causes tool to print the command that would be
+executed but not execute it.
+
+For more about each tool command, see 'go tool command -h'.
+`,
+}
+
+var (
+	toolGOOS      = runtime.GOOS
+	toolGOARCH    = runtime.GOARCH
+	toolIsWindows = toolGOOS == "windows"
+	toolDir       = build.ToolDir
+
+	toolN bool
+)
+
+func init() {
+	cmdTool.Flag.BoolVar(&toolN, "n", false, "")
+}
+
+const toolWindowsExtension = ".exe"
+
+func tool(name string) string {
+	p := filepath.Join(toolDir, name)
+	if toolIsWindows {
+		p += toolWindowsExtension
+	}
+	return p
+}
+
+func runTool(cmd *Command, args []string) {
+	if len(args) == 0 {
+		listTools()
+		return
+	}
+	toolName := args[0]
+	// The tool name must be lower-case letters, numbers or underscores.
+	for _, c := range toolName {
+		switch {
+		case 'a' <= c && c <= 'z', '0' <= c && c <= '9', c == '_':
+		default:
+			fmt.Fprintf(os.Stderr, "go tool: bad tool name %q\n", toolName)
+			setExitStatus(2)
+			return
+		}
+	}
+	toolPath := tool(toolName)
+	// Give a nice message if there is no tool with that name.
+	if _, err := os.Stat(toolPath); err != nil {
+		fmt.Fprintf(os.Stderr, "go tool: no such tool %q\n", toolName)
+		setExitStatus(3)
+		return
+	}
+
+	if toolN {
+		fmt.Printf("%s %s\n", toolPath, strings.Join(args[1:], " "))
+		return
+	}
+	toolCmd := &exec.Cmd{
+		Path:   toolPath,
+		Args:   args,
+		Stdin:  os.Stdin,
+		Stdout: os.Stdout,
+		Stderr: os.Stderr,
+	}
+	err := toolCmd.Run()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "go tool %s: %s\n", toolName, err)
+		setExitStatus(1)
+		return
+	}
+}
+
+// listTools prints a list of the available tools in the tools directory.
+func listTools() {
+	f, err := os.Open(toolDir)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "go tool: no tool directory: %s\n", err)
+		setExitStatus(2)
+		return
+	}
+	defer f.Close()
+	names, err := f.Readdirnames(-1)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "go tool: can't read directory: %s\n", err)
+		setExitStatus(2)
+		return
+	}
+
+	sort.Strings(names)
+	for _, name := range names {
+		// Unify presentation by going to lower case.
+		name = strings.ToLower(name)
+		// If it's windows, don't show the .exe suffix.
+		if toolIsWindows && strings.HasSuffix(name, toolWindowsExtension) {
+			name = name[:len(name)-len(toolWindowsExtension)]
+		}
+		fmt.Println(name)
+	}
+}