libgo/go/os/exec/lp_plan9.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 package exec
   6
   7 import (
   8         "errors"
   9         "io/fs"
  10         "os"
  11         "path/filepath"
  12         "strings"
  13 )
  14
  15 // ErrNotFound is the error resulting if a path search failed to find an executable file.
  16 var ErrNotFound = errors.New("executable file not found in $path")
  17
  18 func findExecutable(file string) error {
  19         d, err := os.Stat(file)
  20         if err != nil {
  21                 return err
  22         }
  23         if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
  24                 return nil
  25         }
  26         return fs.ErrPermission
  27 }
  28
  29 // LookPath searches for an executable named file in the
  30 // directories named by the path environment variable.
  31 // If file begins with "/", "#", "./", or "../", it is tried
  32 // directly and the path is not consulted.
  33 // The result may be an absolute path or a path relative to the current directory.
  34 func LookPath(file string) (string, error) {
  35         // skip the path lookup for these prefixes
  36         skip := []string{"/", "#", "./", "../"}
  37
  38         for _, p := range skip {
  39                 if strings.HasPrefix(file, p) {
  40                         err := findExecutable(file)
  41                         if err == nil {
  42                                 return file, nil
  43                         }
  44                         return "", &Error{file, err}
  45                 }
  46         }
  47
  48         path := os.Getenv("path")
  49         for _, dir := range filepath.SplitList(path) {
  50                 path := filepath.Join(dir, file)
  51                 if err := findExecutable(path); err == nil {
  52                         return path, nil
  53                 }
  54         }
  55         return "", &Error{file, ErrNotFound}
  56 }