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os/exec: reduce arbitrary sleeps in TestWaitid

If we use the "pipetest" helper command instead of "sleep",
we can use its stdout pipe to determine when the process
is ready to handle a SIGSTOP, and we can additionally check
that sending a SIGCONT actually causes the process to continue.

This also allows us to remove the "sleep" helper command,
making the test file somewhat more concise.

Noticed while looking into #50138.

Change-Id: If4fdee4b1ddf28c6ed07ec3268c81b73c2600238
Reviewed-on: https://go-review.googlesource.com/c/go/+/442576
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
This commit is contained in:
Bryan C. Mills 2022-10-12 15:11:16 -04:00 committed by Gopher Robot
parent 379a49c593
commit 498ee73a4b

View File

@ -9,6 +9,7 @@ package exec_test
import (
"fmt"
"internal/testenv"
"io"
"os"
"os/user"
"path/filepath"
@ -23,7 +24,6 @@ import (
func init() {
registerHelperCommand("pwd", cmdPwd)
registerHelperCommand("sleep", cmdSleep)
}
func cmdPwd(...string) {
@ -35,15 +35,6 @@ func cmdPwd(...string) {
fmt.Println(pwd)
}
func cmdSleep(args ...string) {
n, err := strconv.Atoi(args[0])
if err != nil {
fmt.Println(err)
os.Exit(1)
}
time.Sleep(time.Duration(n) * time.Second)
}
func TestCredentialNoSetGroups(t *testing.T) {
if runtime.GOOS == "android" {
maySkipHelperCommand("echo")
@ -86,15 +77,29 @@ func TestCredentialNoSetGroups(t *testing.T) {
func TestWaitid(t *testing.T) {
t.Parallel()
cmd := helperCommand(t, "sleep", "3")
cmd := helperCommand(t, "pipetest")
stdin, err := cmd.StdinPipe()
if err != nil {
t.Fatal(err)
}
stdout, err := cmd.StdoutPipe()
if err != nil {
t.Fatal(err)
}
if err := cmd.Start(); err != nil {
t.Fatal(err)
}
// The sleeps here are unnecessary in the sense that the test
// should still pass, but they are useful to make it more
// likely that we are testing the expected state of the child.
time.Sleep(100 * time.Millisecond)
// Wait for the child process to come up and register any signal handlers.
const msg = "O:ping\n"
if _, err := io.WriteString(stdin, msg); err != nil {
t.Fatal(err)
}
buf := make([]byte, len(msg))
if _, err := io.ReadFull(stdout, buf); err != nil {
t.Fatal(err)
}
// Now leave the pipes open so that the process will hang until we close stdin.
if err := cmd.Process.Signal(syscall.SIGSTOP); err != nil {
cmd.Process.Kill()
@ -106,16 +111,30 @@ func TestWaitid(t *testing.T) {
ch <- cmd.Wait()
}()
time.Sleep(100 * time.Millisecond)
// Give a little time for Wait to block on waiting for the process.
// (This is just to give some time to trigger the bug; it should not be
// necessary for the test to pass.)
if testing.Short() {
time.Sleep(1 * time.Millisecond)
} else {
time.Sleep(10 * time.Millisecond)
}
// This call to Signal should succeed because the process still exists.
// (Prior to the fix for #19314, this would fail with os.ErrProcessDone
// or an equivalent error.)
if err := cmd.Process.Signal(syscall.SIGCONT); err != nil {
t.Error(err)
syscall.Kill(cmd.Process.Pid, syscall.SIGCONT)
}
cmd.Process.Kill()
<-ch
// The SIGCONT should allow the process to wake up, notice that stdin
// is closed, and exit successfully.
stdin.Close()
err = <-ch
if err != nil {
t.Fatal(err)
}
}
// https://go.dev/issue/50599: if Env is not set explicitly, setting Dir should