124 lines
2.7 KiB
Go
124 lines
2.7 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package exec
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import (
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"errors"
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"os"
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"strings"
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)
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// ErrNotFound is the error resulting if a path search failed to find an executable file.
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var ErrNotFound = errors.New("executable file not found in %PATH%")
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func chkStat(file string) error {
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d, err := os.Stat(file)
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if err != nil {
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return err
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}
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if d.IsDir() {
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return os.ErrPermission
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}
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return nil
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}
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func hasExt(file string) bool {
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i := strings.LastIndex(file, ".")
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if i < 0 {
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return false
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}
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return strings.LastIndexAny(file, `:\/`) < i
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}
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func findExecutable(file string, exts []string) (string, error) {
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if len(exts) == 0 {
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return file, chkStat(file)
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}
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if hasExt(file) {
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if chkStat(file) == nil {
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return file, nil
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}
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}
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for _, e := range exts {
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if f := file + e; chkStat(f) == nil {
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return f, nil
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}
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}
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return ``, os.ErrNotExist
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}
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// LookPath searches for an executable binary named file
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// in the directories named by the PATH environment variable.
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// If file contains a slash, it is tried directly and the PATH is not consulted.
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// LookPath also uses PATHEXT environment variable to match
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// a suitable candidate.
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// The result may be an absolute path or a path relative to the current directory.
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func LookPath(file string) (f string, err error) {
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x := os.Getenv(`PATHEXT`)
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if x == `` {
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x = `.COM;.EXE;.BAT;.CMD`
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}
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exts := []string{}
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for _, e := range strings.Split(strings.ToLower(x), `;`) {
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if e == "" {
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continue
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}
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if e[0] != '.' {
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e = "." + e
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}
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exts = append(exts, e)
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}
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if strings.IndexAny(file, `:\/`) != -1 {
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if f, err = findExecutable(file, exts); err == nil {
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return
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}
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return ``, &Error{file, err}
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}
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if f, err = findExecutable(`.\`+file, exts); err == nil {
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return
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}
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if pathenv := os.Getenv(`PATH`); pathenv != `` {
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for _, dir := range splitList(pathenv) {
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if f, err = findExecutable(dir+`\`+file, exts); err == nil {
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return
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}
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}
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}
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return ``, &Error{file, ErrNotFound}
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}
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func splitList(path string) []string {
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// The same implementation is used in SplitList in path/filepath;
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// consider changing path/filepath when changing this.
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if path == "" {
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return []string{}
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}
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// Split path, respecting but preserving quotes.
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list := []string{}
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start := 0
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quo := false
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for i := 0; i < len(path); i++ {
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switch c := path[i]; {
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case c == '"':
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quo = !quo
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case c == os.PathListSeparator && !quo:
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list = append(list, path[start:i])
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start = i + 1
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}
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}
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list = append(list, path[start:])
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// Remove quotes.
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for i, s := range list {
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if strings.Contains(s, `"`) {
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list[i] = strings.Replace(s, `"`, ``, -1)
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}
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}
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return list
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}
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