| // 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. | |
| //go:build unix | |
| package exec | |
| import ( | |
| "errors" | |
| "internal/syscall/unix" | |
| "io/fs" | |
| "os" | |
| "path/filepath" | |
| "strings" | |
| "syscall" | |
| ) | |
| // 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 | |
| } | |
| m := d.Mode() | |
| if m.IsDir() { | |
| return syscall.EISDIR | |
| } | |
| err = unix.Eaccess(file, unix.X_OK) | |
| // ENOSYS means Eaccess is not available or not implemented. | |
| // EPERM can be returned by Linux containers employing seccomp. | |
| // In both cases, fall back to checking the permission bits. | |
| if err == nil || (err != syscall.ENOSYS && err != syscall.EPERM) { | |
| return err | |
| } | |
| if m&0111 != 0 { | |
| return nil | |
| } | |
| return fs.ErrPermission | |
| } | |
| // LookPath searches for an executable 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. | |
| // Otherwise, on success, the result is an absolute path. | |
| // | |
| // In older versions of Go, LookPath could return a path relative to the current directory. | |
| // As of Go 1.19, LookPath will instead return that path along with an error satisfying | |
| // [errors.Is](err, [ErrDot]). See the package documentation for more details. | |
| 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 err := validateLookPath(file); err != nil { | |
| return "", &Error{file, err} | |
| } | |
| 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 { | |
| if !filepath.IsAbs(path) { | |
| if execerrdot.Value() != "0" { | |
| return path, &Error{file, ErrDot} | |
| } | |
| execerrdot.IncNonDefault() | |
| } | |
| return path, nil | |
| } | |
| } | |
| return "", &Error{file, ErrNotFound} | |
| } | |
| // lookExtensions is a no-op on non-Windows platforms, since | |
| // they do not restrict executables to specific extensions. | |
| func lookExtensions(path, dir string) (string, error) { | |
| return path, nil | |
| } | |