Revert "test/testenv: run dial-stdio with Pdeathsig and process group"

test/testenv/buildx.go

@@ -11,10 +11,8 @@ import (
 	"net"
 	"os"
 	"os/exec"
-	"runtime"
 	"strings"
 	"sync"
-	"syscall"
 	"testing"
 	"time"
 
@@ -106,15 +104,6 @@ func (b *BuildxEnv) dialStdio(ctx context.Context) error {
 		// the buildx dial-stdio process from cleaning up its resources properly.
 		cmd := exec.Command("docker", args...)
 		cmd.Env = os.Environ()
-		cmd.SysProcAttr = &syscall.SysProcAttr{
-			// Put the child in its own process group so we can kill the entire
-			// group (docker + docker-buildx plugin) during cleanup.
-			Setpgid: true,
-			// Send SIGTERM to the child process when the parent (test process) dies.
-			// This prevents dial-stdio processes from being orphaned when the test
-			// suite is interrupted or crashes.
-			Pdeathsig: syscall.SIGTERM,
-		}
 
 		c1, c2 := net.Pipe()
 		cmd.Stdin = c1
@@ -128,29 +117,16 @@ func (b *BuildxEnv) dialStdio(ctx context.Context) error {
 		ww := io.MultiWriter(w, errBuf)
 		cmd.Stderr = ww
 
-		// processDone is closed when cmd.Wait() returns, signaling the cleanup
-		// function that the process has exited.
-		processDone := make(chan struct{})
-		go func() {
-			// Lock this goroutine to its OS thread for the lifetime of the child process.
-			// Pdeathsig delivers the signal when the *thread* that forked the child exits,
-			// not when the process exits. Without locking, the Go runtime may destroy the
-			// thread that called cmd.Start(), prematurely delivering SIGTERM to the child.
-			runtime.LockOSThread()
-			defer runtime.UnlockOSThread()
-
-			if err := cmd.Start(); err != nil {
-				// Propagate the start error through the stderr pipe so the
-				// scanner below will surface it via scanner.Err().
-				w.CloseWithError(err)
-				return
-			}
+		if err := cmd.Start(); err != nil {
+			return nil, err
+		}
 
+		chWait := make(chan struct{})
+		go func() {
 			err := cmd.Wait()
-			close(processDone)
 			c1.Close()
 			// pkgerrors.Wrap will return nil if err is nil, otherwise it will give
-			// us a wrapped error with the buffered stderr from the command.
+			// us a wrapped error with the buffered stderr from he command.
 			w.CloseWithError(pkgerrors.Wrapf(err, "%s", errBuf))
 		}()
 
@@ -184,7 +160,7 @@ func (b *BuildxEnv) dialStdio(ctx context.Context) error {
 				}
 
 				select {
-				case <-processDone:
+				case <-chWait:
 				case <-time.After(10 * time.Second):
 					// If it still doesn't exit, force kill
 					cmd.Process.Kill() //nolint:errcheck // Force kill if it doesn't exit after interrupt