Bound subprocess output teardown

internal/process/process.go

@@ -11,6 +11,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"time"
 )
 
 // Invocation describes one child process. UnsetEnv removes inherited values
@@ -135,6 +136,7 @@ func newCommand(ctx context.Context, invocation Invocation) (*exec.Cmd, error) {
 	}
 	command := exec.CommandContext(ctx, invocation.Args[0], invocation.Args[1:]...)
 	command.Dir = invocation.Dir
+	command.WaitDelay = time.Second
 	if len(invocation.Env) != 0 || len(invocation.UnsetEnv) != 0 {
 		command.Env = environmentEntries(invocation.Env, invocation.UnsetEnv)
 	}

internal/process/process_test.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -119,6 +120,68 @@ func TestRunReturnsCancellation(t *testing.T) {
 	}
 }
 
+func TestRunBoundsInheritedOutputPipes(t *testing.T) {
+	for _, mode := range []string{"cancel-descendant", "exit-descendant"} {
+		t.Run(mode, func(t *testing.T) {
+			ready := filepath.Join(t.TempDir(), "descendant")
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+			var output bytes.Buffer
+			result := make(chan error, 1)
+			go func() {
+				result <- Run(ctx, Invocation{
+					Args:   []string{helperExecutable(t), "-test.run=TestProcessHelper", "--", "unused", mode},
+					Env:    map[string]string{"RELEASEKIT_PROCESS_HELPER": "1", "RELEASEKIT_DESCENDANT_READY": ready},
+					Stdout: &output, Stderr: &output,
+				})
+			}()
+			deadline := time.After(10 * time.Second)
+			var pid int
+			for pid == 0 {
+				data, err := os.ReadFile(ready)
+				if err == nil {
+					pid, _ = strconv.Atoi(string(data))
+				}
+				select {
+				case <-deadline:
+					t.Fatal("descendant did not become ready")
+				default:
+					time.Sleep(10 * time.Millisecond)
+				}
+			}
+			t.Cleanup(func() {
+				if process, err := os.FindProcess(pid); err == nil {
+					_ = process.Kill()
+				}
+			})
+			if mode == "cancel-descendant" {
+				cancel()
+			}
+			select {
+			case err := <-result:
+				if mode == "cancel-descendant" && !errors.Is(err, context.Canceled) {
+					t.Fatalf("canceled command error = %v", err)
+				}
+				if mode == "exit-descendant" && !errors.Is(err, exec.ErrWaitDelay) {
+					t.Fatalf("exited command error = %v, want pipe teardown error", err)
+				}
+			case <-time.After(10 * time.Second):
+				t.Fatal("command did not release inherited output pipes")
+			}
+		})
+	}
+}
+
+func TestRunDoesNotLimitHealthyCommandLifetime(t *testing.T) {
+	err := Run(context.Background(), Invocation{
+		Args: []string{helperExecutable(t), "-test.run=TestProcessHelper", "--", "unused", "slow-success"},
+		Env:  map[string]string{"RELEASEKIT_PROCESS_HELPER": "1"},
+	})
+	if err != nil {
+		t.Fatalf("healthy command failed: %v", err)
+	}
+}
+
 func TestStartPipedExchangesBeforeInputEOFAndPreservesSettings(t *testing.T) {
 	workdir := filepath.Join(t.TempDir(), "piped directory")
 	if err := os.Mkdir(workdir, 0o700); err != nil {
@@ -279,11 +342,39 @@ func TestProcessHelper(t *testing.T) {
 		os.Exit(0)
 	case "exit":
 		os.Exit(7)
+	case "slow-success":
+		time.Sleep(1500 * time.Millisecond)
+		os.Exit(0)
 	case "wait":
 		fmt.Fprintln(os.Stdout, "started")
 		for {
 			time.Sleep(time.Second)
 		}
+	case "cancel-descendant", "exit-descendant":
+		child := exec.Command(os.Args[0], "-test.run=TestProcessHelper", "--", "unused", "descendant")
+		child.Stdout, child.Stderr = os.Stdout, os.Stderr
+		if err := child.Start(); err != nil {
+			os.Exit(14)
+		}
+		for {
+			if _, err := os.Stat(os.Getenv("RELEASEKIT_DESCENDANT_READY")); err == nil {
+				break
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+		if mode == "exit-descendant" {
+			os.Exit(0)
+		}
+		for {
+			time.Sleep(time.Second)
+		}
+	case "descendant":
+		if err := os.WriteFile(os.Getenv("RELEASEKIT_DESCENDANT_READY"), []byte(strconv.Itoa(os.Getpid())), 0o600); err != nil {
+			os.Exit(15)
+		}
+		for {
+			time.Sleep(time.Second)
+		}
 	case "exchange":
 		reader := bufio.NewReader(os.Stdin)
 		request, err := reader.ReadString('\n')