tool.go

     1  // Copyright 2017 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 base
     6  
     7  import (
     8  	"fmt"
     9  	"go/build"
    10  	"os"
    11  	"path/filepath"
    12  
    13  	"cmd/go/internal/cfg"
    14  	"cmd/internal/par"
    15  )
    16  
    17  // Tool returns the path to the named builtin tool (for example, "vet").
    18  // If the tool cannot be found, Tool exits the process.
    19  func Tool(toolName string) string {
    20  	toolPath, err := ToolPath(toolName)
    21  	if err != nil && len(cfg.BuildToolexec) == 0 {
    22  		// Give a nice message if there is no tool with that name.
    23  		fmt.Fprintf(os.Stderr, "go: no such tool %q\n", toolName)
    24  		SetExitStatus(2)
    25  		Exit()
    26  	}
    27  	return toolPath
    28  }
    29  
    30  // ToolPath returns the path at which we expect to find the named tool
    31  // (for example, "vet"), and the error (if any) from statting that path.
    32  func ToolPath(toolName string) (string, error) {
    33  	if !validToolName(toolName) {
    34  		return "", fmt.Errorf("bad tool name: %q", toolName)
    35  	}
    36  	toolPath := filepath.Join(build.ToolDir, toolName) + cfg.ToolExeSuffix()
    37  	err := toolStatCache.Do(toolPath, func() error {
    38  		_, err := os.Stat(toolPath)
    39  		return err
    40  	})
    41  	return toolPath, err
    42  }
    43  
    44  func validToolName(toolName string) bool {
    45  	for _, c := range toolName {
    46  		switch {
    47  		case 'a' <= c && c <= 'z', '0' <= c && c <= '9', c == '_':
    48  		default:
    49  			return false
    50  		}
    51  	}
    52  	return true
    53  }
    54  
    55  var toolStatCache par.Cache[string, error]
    56
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