From 960ffa98ce73ef2c2060c84c7ac28d37a83f345e Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Tue, 3 May 2022 15:14:56 -0400 Subject: [PATCH] os/exec: return clear error for missing cmd.Path Following up on CL 403694, there is a bit of confusion about when Path is and isn't set, along with now the exported Err field. Catch the case where Path and Err (and lookPathErr) are all unset and give a helpful error. Fixes #52574 Followup after #43724. Change-Id: I03205172aef3801c3194f5098bdb93290c02b1b6 Reviewed-on: https://go-review.googlesource.com/c/go/+/403759 Reviewed-by: Bryan Mills Reviewed-by: Roland Shoemaker --- src/os/exec/exec.go | 3 +++ src/os/exec/exec_test.go | 8 ++++++++ 2 files changed, 11 insertions(+) diff --git a/src/os/exec/exec.go b/src/os/exec/exec.go index 8101e718ff..f0dc7dab7d 100644 --- a/src/os/exec/exec.go +++ b/src/os/exec/exec.go @@ -465,6 +465,9 @@ func lookExtensions(path, dir string) (string, error) { // The Wait method will return the exit code and release associated resources // once the command exits. func (c *Cmd) Start() error { + if c.Path == "" && c.Err == nil && c.lookPathErr == nil { + c.Err = errors.New("exec: no command") + } if c.Err != nil || c.lookPathErr != nil { c.closeDescriptors(c.closeAfterStart) c.closeDescriptors(c.closeAfterWait) diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go index c593cbd11d..9cc14bdaca 100644 --- a/src/os/exec/exec_test.go +++ b/src/os/exec/exec_test.go @@ -1125,3 +1125,11 @@ func TestStringPathNotResolved(t *testing.T) { t.Errorf("String(%q, %q) = %q, want %q", "makemeasandwich", "-lettuce", got, want) } } + +func TestNoPath(t *testing.T) { + err := new(exec.Cmd).Start() + want := "exec: no command" + if err == nil || err.Error() != want { + t.Errorf("new(Cmd).Start() = %v, want %q", err, want) + } +}