libgo/go/exec/lp_unix.go

   1 // Copyright 2010 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         "os"
   9         "strings"
  10 )
  11
  12 func canExec(file string) bool {
  13         d, err := os.Stat(file)
  14         if err != nil {
  15                 return false
  16         }
  17         return d.IsRegular() && d.Permission()&0111 != 0
  18 }
  19
  20 // LookPath searches for an executable binary named file
  21 // in the directories named by the PATH environment variable.
  22 // If file contains a slash, it is tried directly and the PATH is not consulted.
  23 func LookPath(file string) (string, os.Error) {
  24         // NOTE(rsc): I wish we could use the Plan 9 behavior here
  25         // (only bypass the path if file begins with / or ./ or ../)
  26         // but that would not match all the Unix shells.
  27
  28         if strings.Contains(file, "/") {
  29                 if canExec(file) {
  30                         return file, nil
  31                 }
  32                 return "", os.ENOENT
  33         }
  34         pathenv := os.Getenv("PATH")
  35         for _, dir := range strings.Split(pathenv, ":", -1) {
  36                 if dir == "" {
  37                         // Unix shell semantics: path element "" means "."
  38                         dir = "."
  39                 }
  40                 if canExec(dir + "/" + file) {
  41                         return dir + "/" + file, nil
  42                 }
  43         }
  44         return "", os.ENOENT
  45 }