bash tool: kill the whole process tree on timeout (process group on Unix, taskkill /T on Windows)

Author: AgentiLoop

tools/proc_unix.go

@@ -0,0 +1,17 @@
+//go:build !windows
+
+package tools
+
+import (
+	"os/exec"
+	"syscall"
+)
+
+// killTreeOnCancel runs the command in its own process group and kills the
+// whole group on timeout, so children of `sh -c` don't outlive it.
+func killTreeOnCancel(cmd *exec.Cmd) {
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	cmd.Cancel = func() error {
+		return syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+	}
+}

tools/proc_windows.go

@@ -0,0 +1,20 @@
+//go:build windows
+
+package tools
+
+import (
+	"os/exec"
+	"strconv"
+)
+
+// killTreeOnCancel kills the whole process tree on timeout, so children of
+// `cmd /C` don't outlive it (and keep the working directory locked).
+func killTreeOnCancel(cmd *exec.Cmd) {
+	cmd.Cancel = func() error {
+		kill := exec.Command("taskkill", "/T", "/F", "/PID", strconv.Itoa(cmd.Process.Pid))
+		if err := kill.Run(); err != nil {
+			return cmd.Process.Kill()
+		}
+		return nil
+	}
+}

tools/tools.go

@@ -261,6 +261,7 @@ func (Bash) Call(ctx context.Context, tc core.ToolContext, input json.RawMessage
 		cmd = exec.CommandContext(ctx, "sh", "-c", a.Command)
 	}
 	cmd.Dir = tc.Cwd
+	killTreeOnCancel(cmd)
 	cmd.WaitDelay = time.Second // don't hang on grandchildren holding the pipes
 	var stdout, stderr strings.Builder
 	cmd.Stdout, cmd.Stderr = &stdout, &stderr

tools/tree_test.go

@@ -0,0 +1,21 @@
+//go:build !windows
+
+package tools
+
+import (
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestBashTimeoutKillsChildren(t *testing.T) {
+	_, err := call(t, Bash{}, t.TempDir(), `{"command":"sleep 7.123 & sleep 7.123; wait","timeout_secs":1}`)
+	if err == nil || !strings.Contains(err.Error(), "timed out") {
+		t.Fatal(err)
+	}
+	time.Sleep(200 * time.Millisecond)
+	if out, _ := exec.Command("pgrep", "-f", "sleep 7.123").Output(); len(out) > 0 {
+		t.Fatalf("children survived: %s", out)
+	}
+}