From: Ian Lance Taylor Date: Tue, 12 Sep 2023 00:07:55 +0000 (+0000) Subject: Revert "os/exec: avoid calling LookPath in cmd.Start for resolved paths" X-Git-Tag: go1.22rc1~895 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8221f90f1347bd96548d48b178c8bcb0607cde8f;p=gostls13.git Revert "os/exec: avoid calling LookPath in cmd.Start for resolved paths" This reverts CL 512155. Reason for revert: CL 512155 introduced a race in that it caused cmd.Start to set cmd.Path. Previously it was fine if code looked at cmd.Path in one goroutine while calling cmd.Start in a different goroutine. A test case for this race is in CL 527495. Change-Id: Ic18fdadf6763727f8ea748280d5f0e601b9bf374 Reviewed-on: https://go-review.googlesource.com/c/go/+/527337 Auto-Submit: Ian Lance Taylor Reviewed-by: Ian Lance Taylor LUCI-TryBot-Result: Go LUCI Reviewed-by: Matthew Dempsky --- diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go index 2881345fb3..dfede0e7e2 100644 --- a/src/os/exec/exec.go +++ b/src/os/exec/exec.go @@ -590,6 +590,32 @@ func (c *Cmd) Run() error { return c.Wait() } +// lookExtensions finds windows executable by its dir and path. +// It uses LookPath to try appropriate extensions. +// lookExtensions does not search PATH, instead it converts `prog` into `.\prog`. +func lookExtensions(path, dir string) (string, error) { + if filepath.Base(path) == path { + path = "." + string(filepath.Separator) + path + } + if dir == "" { + return LookPath(path) + } + if filepath.VolumeName(path) != "" { + return LookPath(path) + } + if len(path) > 1 && os.IsPathSeparator(path[0]) { + return LookPath(path) + } + dirandpath := filepath.Join(dir, path) + // We assume that LookPath will only add file extension. + lp, err := LookPath(dirandpath) + if err != nil { + return "", err + } + ext := strings.TrimPrefix(lp, dirandpath) + return path + ext, nil +} + // Start starts the specified command but does not wait for it to complete. // // If Start returns successfully, the c.Process field will be set. @@ -623,11 +649,13 @@ func (c *Cmd) Start() error { } return c.Err } - lp, err := lookExtensions(c.Path, c.Dir) - if err != nil { - return err + if runtime.GOOS == "windows" { + lp, err := lookExtensions(c.Path, c.Dir) + if err != nil { + return err + } + c.Path = lp } - c.Path = lp if c.Cancel != nil && c.ctx == nil { return errors.New("exec: command with a non-nil Cancel was not created with CommandContext") } diff --git a/src/os/exec/lp_plan9.go b/src/os/exec/lp_plan9.go index dffdbac35f..9344b14e8c 100644 --- a/src/os/exec/lp_plan9.go +++ b/src/os/exec/lp_plan9.go @@ -64,9 +64,3 @@ func LookPath(file string) (string, error) { } 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 -} diff --git a/src/os/exec/lp_unix.go b/src/os/exec/lp_unix.go index 3787132078..fd2c6efbef 100644 --- a/src/os/exec/lp_unix.go +++ b/src/os/exec/lp_unix.go @@ -80,9 +80,3 @@ func LookPath(file string) (string, error) { } 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 -} diff --git a/src/os/exec/lp_wasm.go b/src/os/exec/lp_wasm.go index 3c819049ba..f2c8e9c5de 100644 --- a/src/os/exec/lp_wasm.go +++ b/src/os/exec/lp_wasm.go @@ -21,9 +21,3 @@ func LookPath(file string) (string, error) { // Wasm can not execute processes, so act as if there are no executables at all. 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 -} diff --git a/src/os/exec/lp_windows.go b/src/os/exec/lp_windows.go index 7f13347c50..066d38dfdb 100644 --- a/src/os/exec/lp_windows.go +++ b/src/os/exec/lp_windows.go @@ -63,45 +63,6 @@ func findExecutable(file string, exts []string) (string, error) { // 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) { - return lookPath(file, pathExt()) -} - -// lookExtensions finds windows executable by its dir and path. -// It uses LookPath to try appropriate extensions. -// lookExtensions does not search PATH, instead it converts `prog` into `.\prog`. -func lookExtensions(path, dir string) (string, error) { - if filepath.Base(path) == path { - path = "." + string(filepath.Separator) + path - } - exts := pathExt() - if ext := filepath.Ext(path); ext != "" { - for _, e := range exts { - if strings.EqualFold(ext, e) { - // Assume that path has already been resolved. - return path, nil - } - } - } - if dir == "" { - return lookPath(path, exts) - } - if filepath.VolumeName(path) != "" { - return lookPath(path, exts) - } - if len(path) > 1 && os.IsPathSeparator(path[0]) { - return lookPath(path, exts) - } - dirandpath := filepath.Join(dir, path) - // We assume that LookPath will only add file extension. - lp, err := lookPath(dirandpath, exts) - if err != nil { - return "", err - } - ext := strings.TrimPrefix(lp, dirandpath) - return path + ext, nil -} - -func pathExt() []string { var exts []string x := os.Getenv(`PATHEXT`) if x != "" { @@ -117,11 +78,7 @@ func pathExt() []string { } else { exts = []string{".com", ".exe", ".bat", ".cmd"} } - return exts -} -// lookPath implements LookPath for the given PATHEXT list. -func lookPath(file string, exts []string) (string, error) { if strings.ContainsAny(file, `:\/`) { f, err := findExecutable(file, exts) if err == nil {