libgo/go/os/executable_path.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 // +build aix
   6
   7 package os
   8
   9 // We query the working directory at init, to use it later to search for the
  10 // executable file
  11 // errWd will be checked later, if we need to use initWd
  12 var initWd, errWd = Getwd()
  13
  14 func executable() (string, error) {
  15         var err error
  16         var exePath string
  17         if len(Args) == 0 || Args[0] == "" {
  18                 return "", ErrNotExist
  19         }
  20         // Args[0] is an absolute path : this is the executable
  21         if IsPathSeparator(Args[0][0]) {
  22                 exePath = Args[0]
  23         } else {
  24                 for i := 1; i < len(Args[0]); i++ {
  25                         // Args[0] is a relative path : append current directory
  26                         if IsPathSeparator(Args[0][i]) {
  27                                 if errWd != nil {
  28                                         return "", errWd
  29                                 }
  30                                 exePath = initWd + string(PathSeparator) + Args[0]
  31                                 break
  32                         }
  33                 }
  34         }
  35         if exePath != "" {
  36                 err = isExecutable(exePath)
  37                 if err == nil {
  38                         return exePath, nil
  39                 }
  40                 // File does not exist or is not executable,
  41                 // this is an unexpected situation !
  42                 return "", err
  43         }
  44         // Search for executable in $PATH
  45         for _, dir := range splitPathList(Getenv("PATH")) {
  46                 if len(dir) == 0 {
  47                         continue
  48                 }
  49                 if !IsPathSeparator(dir[0]) {
  50                         if errWd != nil {
  51                                 return "", errWd
  52                         }
  53                         dir = initWd + string(PathSeparator) + dir
  54                 }
  55                 exePath = dir + string(PathSeparator) + Args[0]
  56                 err = isExecutable(exePath)
  57                 if err == nil {
  58                         return exePath, nil
  59                 }
  60                 if err == ErrPermission {
  61                         return "", err
  62                 }
  63         }
  64         return "", ErrNotExist
  65 }
  66
  67 // isExecutable returns an error if a given file is not an executable.
  68 func isExecutable(path string) error {
  69         stat, err := Stat(path)
  70         if err != nil {
  71                 return err
  72         }
  73         mode := stat.Mode()
  74         if !mode.IsRegular() {
  75                 return ErrPermission
  76         }
  77         if (mode & 0111) != 0 {
  78                 return nil
  79         }
  80         return ErrPermission
  81 }
  82
  83 // splitPathList splits a path list.
  84 // This is based on genSplit from strings/strings.go
  85 func splitPathList(pathList string) []string {
  86         n := 1
  87         for i := 0; i < len(pathList); i++ {
  88                 if pathList[i] == PathListSeparator {
  89                         n++
  90                 }
  91         }
  92         start := 0
  93         a := make([]string, n)
  94         na := 0
  95         for i := 0; i+1 <= len(pathList) && na+1 < n; i++ {
  96                 if pathList[i] == PathListSeparator {
  97                         a[na] = pathList[start:i]
  98                         na++
  99                         start = i + 1
 100                 }
 101         }
 102         a[na] = pathList[start:]
 103         return a[:na+1]
 104 }