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// 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.
package exec
import (
"os"
"strings"
)
// ErrNotFound is the error resulting if a path search failed to find an executable file.
var ErrNotFound = os.ErrorString("executable file not found in $PATH")
func findExecutable(file string) os.Error {
d, err := os.Stat(file)
if err != nil {
return err
}
if d.IsRegular() && d.Permission()&0111 != 0 {
return nil
}
return os.EPERM
}
// 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.
func LookPath(file string) (string, os.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}
}
pathenv := os.Getenv("PATH")
for _, dir := range strings.Split(pathenv, ":", -1) {
if dir == "" {
// Unix shell semantics: path element "" means "."
dir = "."
}
if err := findExecutable(dir + "/" + file); err == nil {
return dir + "/" + file, nil
}
}
return "", &Error{file, ErrNotFound}
}
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