Source file src/os/exec/lp_windows.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		"errors"
     9		"os"
    10		"path/filepath"
    11		"strings"
    12	)
    13	
    14	// ErrNotFound is the error resulting if a path search failed to find an executable file.
    15	var ErrNotFound = errors.New("executable file not found in %PATH%")
    16	
    17	func chkStat(file string) error {
    18		d, err := os.Stat(file)
    19		if err != nil {
    20			return err
    21		}
    22		if d.IsDir() {
    23			return os.ErrPermission
    24		}
    25		return nil
    26	}
    27	
    28	func hasExt(file string) bool {
    29		i := strings.LastIndex(file, ".")
    30		if i < 0 {
    31			return false
    32		}
    33		return strings.LastIndexAny(file, `:\/`) < i
    34	}
    35	
    36	func findExecutable(file string, exts []string) (string, error) {
    37		if len(exts) == 0 {
    38			return file, chkStat(file)
    39		}
    40		if hasExt(file) {
    41			if chkStat(file) == nil {
    42				return file, nil
    43			}
    44		}
    45		for _, e := range exts {
    46			if f := file + e; chkStat(f) == nil {
    47				return f, nil
    48			}
    49		}
    50		return "", os.ErrNotExist
    51	}
    52	
    53	// LookPath searches for an executable named file in the
    54	// directories named by the PATH environment variable.
    55	// If file contains a slash, it is tried directly and the PATH is not consulted.
    56	// LookPath also uses PATHEXT environment variable to match
    57	// a suitable candidate.
    58	// The result may be an absolute path or a path relative to the current directory.
    59	func LookPath(file string) (string, error) {
    60		var exts []string
    61		x := os.Getenv(`PATHEXT`)
    62		if x != "" {
    63			for _, e := range strings.Split(strings.ToLower(x), `;`) {
    64				if e == "" {
    65					continue
    66				}
    67				if e[0] != '.' {
    68					e = "." + e
    69				}
    70				exts = append(exts, e)
    71			}
    72		} else {
    73			exts = []string{".com", ".exe", ".bat", ".cmd"}
    74		}
    75	
    76		if strings.ContainsAny(file, `:\/`) {
    77			if f, err := findExecutable(file, exts); err == nil {
    78				return f, nil
    79			} else {
    80				return "", &Error{file, err}
    81			}
    82		}
    83		if f, err := findExecutable(filepath.Join(".", file), exts); err == nil {
    84			return f, nil
    85		}
    86		path := os.Getenv("path")
    87		for _, dir := range filepath.SplitList(path) {
    88			if f, err := findExecutable(filepath.Join(dir, file), exts); err == nil {
    89				return f, nil
    90			}
    91		}
    92		return "", &Error{file, ErrNotFound}
    93	}
    94	

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