debuginfo: Add a timeout for LLDB tests.

Fixes #18649.

Author: michaelwoerister

src/etc/lldb_batchmode.py

@@ -28,6 +28,7 @@
 import os
 import sys
 import threading
+import thread
 import re
 import atexit
 import time
@@ -131,6 +132,22 @@ def listen():
   target.GetBroadcaster().AddListener(listener, lldb.SBTarget.eBroadcastBitBreakpointChanged)
 
 
+def start_watchdog():
+  "Starts a watchdog thread that will terminate the process after a certain period of time"
+  watchdog_start_time = time.clock()
+  watchdog_max_time = watchdog_start_time + 30
+
+  def watchdog():
+    while time.clock() < watchdog_max_time:
+      time.sleep(1)
+    print("TIMEOUT: lldb_batchmode.py has been running for too long. Aborting!")
+    thread.interrupt_main()
+
+  # Start the listener and let it run as a daemon
+  watchdog_thread = threading.Thread(target = watchdog)
+  watchdog_thread.daemon = True
+  watchdog_thread.start()
+
 ####################################################################################################
 # ~main
 ####################################################################################################
@@ -148,6 +165,9 @@ def listen():
 print("Target executable is '%s'." % target_path)
 print("Current working directory is '%s'" % os.getcwd())
 
+# Start the timeout watchdog
+start_watchdog()
+
 # Create a new debugger instance
 debugger = lldb.SBDebugger.Create()