Source file src/pkg/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		"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 findExecutable(file string) error {
    18		d, err := os.Stat(file)
    19		if err != nil {
    20			return err
    21		}
    22		if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
    23			return nil
    24		}
    25		return os.ErrPermission
    26	}
    27	
    28	// LookPath searches for an executable named file in the
    29	// directories named by the path environment variable.
    30	// If file begins with "/", "#", "./", or "../", it is tried
    31	// directly and the path is not consulted.
    32	// The result may be an absolute path or a path relative to the current directory.
    33	func LookPath(file string) (string, error) {
    34		// skip the path lookup for these prefixes
    35		skip := []string{"/", "#", "./", "../"}
    36	
    37		for _, p := range skip {
    38			if strings.HasPrefix(file, p) {
    39				err := findExecutable(file)
    40				if err == nil {
    41					return file, nil
    42				}
    43				return "", &Error{file, err}
    44			}
    45		}
    46	
    47		path := os.Getenv("path")
    48		for _, dir := range filepath.SplitList(path) {
    49			path := filepath.Join(dir, file)
    50			if err := findExecutable(path); err == nil {
    51				return path, nil
    52			}
    53		}
    54		return "", &Error{file, ErrNotFound}
    55	}
    56	

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