| // Copyright 2010 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris |
| |
| package exec |
| |
| import ( |
| "errors" |
| "os" |
| "path/filepath" |
| "strings" |
| ) |
| |
| // ErrNotFound is the error resulting if a path search failed to find an executable file. |
| var ErrNotFound = errors.New("executable file not found in $PATH") |
| |
| func findExecutable(file string) error { |
| d, err := os.Stat(file) |
| if err != nil { |
| return err |
| } |
| if m := d.Mode(); !m.IsDir() && m&0111 != 0 { |
| return nil |
| } |
| return os.ErrPermission |
| } |
| |
| // LookPath searches for an executable binary named file |
| // in the directories named by the PATH environment variable. |
| // If file contains a slash, it is tried directly and the PATH is not consulted. |
| // The result may be an absolute path or a path relative to the current directory. |
| func LookPath(file string) (string, error) { |
| // NOTE(rsc): I wish we could use the Plan 9 behavior here |
| // (only bypass the path if file begins with / or ./ or ../) |
| // but that would not match all the Unix shells. |
| |
| if strings.Contains(file, "/") { |
| err := findExecutable(file) |
| if err == nil { |
| return file, nil |
| } |
| return "", &Error{file, err} |
| } |
| path := os.Getenv("PATH") |
| for _, dir := range filepath.SplitList(path) { |
| if dir == "" { |
| // Unix shell semantics: path element "" means "." |
| dir = "." |
| } |
| path := filepath.Join(dir, file) |
| if err := findExecutable(path); err == nil { |
| return path, nil |
| } |
| } |
| return "", &Error{file, ErrNotFound} |
| } |