github.com/ader1990/go@v0.0.0-20140630135419-8c24447fa791/src/pkg/os/exec/lp_windows.go (about)

     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  	"errors"
     9  	"os"
    10  	"strings"
    11  )
    12  
    13  // ErrNotFound is the error resulting if a path search failed to find an executable file.
    14  var ErrNotFound = errors.New("executable file not found in %PATH%")
    15  
    16  func chkStat(file string) error {
    17  	d, err := os.Stat(file)
    18  	if err != nil {
    19  		return err
    20  	}
    21  	if d.IsDir() {
    22  		return os.ErrPermission
    23  	}
    24  	return nil
    25  }
    26  
    27  func hasExt(file string) bool {
    28  	i := strings.LastIndex(file, ".")
    29  	if i < 0 {
    30  		return false
    31  	}
    32  	return strings.LastIndexAny(file, `:\/`) < i
    33  }
    34  
    35  func findExecutable(file string, exts []string) (string, error) {
    36  	if len(exts) == 0 {
    37  		return file, chkStat(file)
    38  	}
    39  	if hasExt(file) {
    40  		if chkStat(file) == nil {
    41  			return file, nil
    42  		}
    43  	}
    44  	for _, e := range exts {
    45  		if f := file + e; chkStat(f) == nil {
    46  			return f, nil
    47  		}
    48  	}
    49  	return ``, os.ErrNotExist
    50  }
    51  
    52  // LookPath searches for an executable binary named file
    53  // in the directories named by the PATH environment variable.
    54  // If file contains a slash, it is tried directly and the PATH is not consulted.
    55  // LookPath also uses PATHEXT environment variable to match
    56  // a suitable candidate.
    57  // The result may be an absolute path or a path relative to the current directory.
    58  func LookPath(file string) (f string, err error) {
    59  	x := os.Getenv(`PATHEXT`)
    60  	if x == `` {
    61  		x = `.COM;.EXE;.BAT;.CMD`
    62  	}
    63  	exts := []string{}
    64  	for _, e := range strings.Split(strings.ToLower(x), `;`) {
    65  		if e == "" {
    66  			continue
    67  		}
    68  		if e[0] != '.' {
    69  			e = "." + e
    70  		}
    71  		exts = append(exts, e)
    72  	}
    73  	if strings.IndexAny(file, `:\/`) != -1 {
    74  		if f, err = findExecutable(file, exts); err == nil {
    75  			return
    76  		}
    77  		return ``, &Error{file, err}
    78  	}
    79  	if f, err = findExecutable(`.\`+file, exts); err == nil {
    80  		return
    81  	}
    82  	if pathenv := os.Getenv(`PATH`); pathenv != `` {
    83  		for _, dir := range splitList(pathenv) {
    84  			if f, err = findExecutable(dir+`\`+file, exts); err == nil {
    85  				return
    86  			}
    87  		}
    88  	}
    89  	return ``, &Error{file, ErrNotFound}
    90  }
    91  
    92  func splitList(path string) []string {
    93  	// The same implementation is used in SplitList in path/filepath;
    94  	// consider changing path/filepath when changing this.
    95  
    96  	if path == "" {
    97  		return []string{}
    98  	}
    99  
   100  	// Split path, respecting but preserving quotes.
   101  	list := []string{}
   102  	start := 0
   103  	quo := false
   104  	for i := 0; i < len(path); i++ {
   105  		switch c := path[i]; {
   106  		case c == '"':
   107  			quo = !quo
   108  		case c == os.PathListSeparator && !quo:
   109  			list = append(list, path[start:i])
   110  			start = i + 1
   111  		}
   112  	}
   113  	list = append(list, path[start:])
   114  
   115  	// Remove quotes.
   116  	for i, s := range list {
   117  		if strings.Contains(s, `"`) {
   118  			list[i] = strings.Replace(s, `"`, ``, -1)
   119  		}
   120  	}
   121  
   122  	return list
   123  }