From 4d6ca68a85e42c75683bc96aa540207566f54e26 Mon Sep 17 00:00:00 2001 From: "Bryan C. Mills" Date: Wed, 28 Sep 2022 13:29:12 -0400 Subject: os/exec: do not close pipes on a double-Start error This fixes a bug introduced in CL 401834 in which calling Start twice with pipes attached to a command would spuriously close those pipes when returning the error from the second Start call. For #50436. Change-Id: I3563cc99c0a0987752190fef95da3e9927a76fda Reviewed-on: https://go-review.googlesource.com/c/go/+/436095 Reviewed-by: Ian Lance Taylor TryBot-Result: Gopher Robot Run-TryBot: Bryan Mills Auto-Submit: Bryan Mills --- src/os/exec/exec_test.go | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'src/os/exec/exec_test.go') diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go index 52001bf9e3..07ac0cf3d4 100644 --- a/src/os/exec/exec_test.go +++ b/src/os/exec/exec_test.go @@ -1094,3 +1094,46 @@ func TestNoPath(t *testing.T) { t.Errorf("new(Cmd).Start() = %v, want %q", err, want) } } + +// TestDoubleStartLeavesPipesOpen checks for a regression in which calling +// Start twice, which returns an error on the second call, would spuriously +// close the pipes established in the first call. +func TestDoubleStartLeavesPipesOpen(t *testing.T) { + cmd := helperCommand(t, "pipetest") + in, err := cmd.StdinPipe() + if err != nil { + t.Fatal(err) + } + out, err := cmd.StdoutPipe() + if err != nil { + t.Fatal(err) + } + if err := cmd.Start(); err != nil { + t.Fatal(err) + } + if err := cmd.Start(); err == nil || !strings.HasSuffix(err.Error(), "already started") { + t.Fatalf("second call to Start returned a nil; want an 'already started' error") + } + + outc := make(chan []byte, 1) + go func() { + b, err := io.ReadAll(out) + if err != nil { + t.Error(err) + } + outc <- b + }() + + const msg = "O:Hello, pipe!\n" + + _, err = io.WriteString(in, msg) + if err != nil { + t.Fatal(err) + } + in.Close() + + b := <-outc + if !bytes.Equal(b, []byte(msg)) { + t.Fatalf("read %q from stdout pipe; want %q", b, msg) + } +} -- cgit v1.3