// Copyright 2011 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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"path/filepath"
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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 findExecutable(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 m := d.Mode(); !m.IsDir() && m&0111 != 0 {
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return nil
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}
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return os.ErrPermission
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}
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// LookPath searches for an executable named file in the
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// directories named by the path environment variable.
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// If file begins with "/", "#", "./", or "../", it is tried
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// directly and the path is not consulted.
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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) (string, error) {
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// skip the path lookup for these prefixes
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skip := []string{"/", "#", "./", "../"}
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for _, p := range skip {
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if strings.HasPrefix(file, p) {
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err := findExecutable(file)
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if err == nil {
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return file, nil
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}
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return "", &Error{file, err}
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}
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}
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path := os.Getenv("path")
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for _, dir := range filepath.SplitList(path) {
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path := filepath.Join(dir, file)
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if err := findExecutable(path); err == nil {
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return path, nil
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}
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}
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return "", &Error{file, ErrNotFound}
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}
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