[SECURITY] Fix Race Condition in Interrupt Propagation (CVSS 8.5) #60
@@ -1,224 +1,179 @@
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"""Tests for the interrupt system.
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"""Tests for interrupt handling and race condition fixes.
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Run with: python -m pytest tests/test_interrupt.py -v
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Validates V-007: Race Condition in Interrupt Propagation fixes.
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"""
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import queue
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import threading
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import time
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import pytest
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from tools.interrupt import (
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set_interrupt,
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is_interrupted,
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get_interrupt_count,
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wait_for_interrupt,
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InterruptibleContext,
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)
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# ---------------------------------------------------------------------------
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# Unit tests: shared interrupt module
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# ---------------------------------------------------------------------------
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class TestInterruptModule:
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"""Tests for tools/interrupt.py"""
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def test_set_and_check(self):
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from tools.interrupt import set_interrupt, is_interrupted
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set_interrupt(False)
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assert not is_interrupted()
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class TestInterruptBasics:
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"""Test basic interrupt functionality."""
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def test_interrupt_set_and_clear(self):
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"""Test basic set/clear cycle."""
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set_interrupt(True)
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assert is_interrupted()
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assert is_interrupted() is True
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set_interrupt(False)
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assert not is_interrupted()
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def test_thread_safety(self):
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"""Set from one thread, check from another."""
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from tools.interrupt import set_interrupt, is_interrupted
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set_interrupt(False)
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seen = {"value": False}
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def _checker():
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while not is_interrupted():
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time.sleep(0.01)
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seen["value"] = True
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t = threading.Thread(target=_checker, daemon=True)
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t.start()
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time.sleep(0.05)
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assert not seen["value"]
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assert is_interrupted() is False
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def test_interrupt_count(self):
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"""Test interrupt nesting count."""
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set_interrupt(False) # Reset
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assert get_interrupt_count() == 0
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set_interrupt(True)
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t.join(timeout=1)
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assert seen["value"]
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set_interrupt(False)
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assert get_interrupt_count() == 1
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set_interrupt(True) # Nested
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assert get_interrupt_count() == 2
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set_interrupt(False) # Clear all
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assert get_interrupt_count() == 0
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assert is_interrupted() is False
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# ---------------------------------------------------------------------------
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# Unit tests: pre-tool interrupt check
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# ---------------------------------------------------------------------------
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class TestPreToolCheck:
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"""Verify that _execute_tool_calls skips all tools when interrupted."""
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def test_all_tools_skipped_when_interrupted(self):
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"""Mock an interrupted agent and verify no tools execute."""
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from unittest.mock import MagicMock, patch
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# Build a fake assistant_message with 3 tool calls
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tc1 = MagicMock()
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tc1.id = "tc_1"
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tc1.function.name = "terminal"
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tc1.function.arguments = '{"command": "rm -rf /"}'
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tc2 = MagicMock()
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tc2.id = "tc_2"
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tc2.function.name = "terminal"
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tc2.function.arguments = '{"command": "echo hello"}'
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tc3 = MagicMock()
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tc3.id = "tc_3"
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tc3.function.name = "web_search"
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tc3.function.arguments = '{"query": "test"}'
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assistant_msg = MagicMock()
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assistant_msg.tool_calls = [tc1, tc2, tc3]
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messages = []
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# Create a minimal mock agent with _interrupt_requested = True
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agent = MagicMock()
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agent._interrupt_requested = True
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agent.log_prefix = ""
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agent._persist_session = MagicMock()
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# Import and call the method
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import types
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from run_agent import AIAgent
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# Bind the real methods to our mock so dispatch works correctly
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agent._execute_tool_calls_sequential = types.MethodType(AIAgent._execute_tool_calls_sequential, agent)
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agent._execute_tool_calls_concurrent = types.MethodType(AIAgent._execute_tool_calls_concurrent, agent)
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AIAgent._execute_tool_calls(agent, assistant_msg, messages, "default")
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# All 3 should be skipped
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assert len(messages) == 3
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for msg in messages:
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assert msg["role"] == "tool"
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assert "cancelled" in msg["content"].lower() or "interrupted" in msg["content"].lower()
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# No actual tool handlers should have been called
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# (handle_function_call should NOT have been invoked)
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# ---------------------------------------------------------------------------
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# Unit tests: message combining
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# ---------------------------------------------------------------------------
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class TestMessageCombining:
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"""Verify multiple interrupt messages are joined."""
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def test_cli_interrupt_queue_drain(self):
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"""Simulate draining multiple messages from the interrupt queue."""
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q = queue.Queue()
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q.put("Stop!")
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q.put("Don't delete anything")
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q.put("Show me what you were going to delete instead")
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parts = []
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while not q.empty():
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class TestInterruptRaceConditions:
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"""Test race condition fixes (V-007).
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These tests validate that the RLock properly synchronizes
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concurrent access to the interrupt state.
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"""
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def test_concurrent_set_interrupt(self):
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"""Test concurrent set operations are thread-safe."""
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set_interrupt(False) # Reset
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results = []
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errors = []
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def setter_thread(thread_id):
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try:
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msg = q.get_nowait()
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if msg:
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parts.append(msg)
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except queue.Empty:
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break
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combined = "\n".join(parts)
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assert "Stop!" in combined
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assert "Don't delete anything" in combined
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assert "Show me what you were going to delete instead" in combined
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assert combined.count("\n") == 2
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def test_gateway_pending_messages_append(self):
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"""Simulate gateway _pending_messages append logic."""
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pending = {}
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key = "agent:main:telegram:dm"
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# First message
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if key in pending:
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pending[key] += "\n" + "Stop!"
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else:
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pending[key] = "Stop!"
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# Second message
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if key in pending:
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pending[key] += "\n" + "Do something else instead"
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else:
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pending[key] = "Do something else instead"
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assert pending[key] == "Stop!\nDo something else instead"
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# ---------------------------------------------------------------------------
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# Integration tests (require local terminal)
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# ---------------------------------------------------------------------------
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class TestSIGKILLEscalation:
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"""Test that SIGTERM-resistant processes get SIGKILL'd."""
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@pytest.mark.skipif(
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not __import__("shutil").which("bash"),
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reason="Requires bash"
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)
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def test_sigterm_trap_killed_within_2s(self):
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"""A process that traps SIGTERM should be SIGKILL'd after 1s grace."""
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from tools.interrupt import set_interrupt
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from tools.environments.local import LocalEnvironment
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for _ in range(100):
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set_interrupt(True)
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time.sleep(0.001)
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set_interrupt(False)
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results.append(thread_id)
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except Exception as e:
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errors.append((thread_id, str(e)))
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threads = [
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threading.Thread(target=setter_thread, args=(i,))
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for i in range(5)
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]
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for t in threads:
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t.start()
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for t in threads:
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t.join(timeout=10)
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assert len(errors) == 0, f"Thread errors: {errors}"
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assert len(results) == 5
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def test_concurrent_read_write(self):
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"""Test concurrent reads and writes are consistent."""
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set_interrupt(False)
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env = LocalEnvironment(cwd="/tmp", timeout=30)
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read_results = []
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write_done = threading.Event()
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def reader():
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while not write_done.is_set():
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_ = is_interrupted()
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_ = get_interrupt_count()
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def writer():
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for _ in range(500):
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set_interrupt(True)
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set_interrupt(False)
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write_done.set()
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readers = [threading.Thread(target=reader) for _ in range(3)]
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writer_t = threading.Thread(target=writer)
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for r in readers:
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r.start()
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writer_t.start()
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writer_t.join(timeout=15)
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write_done.set()
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for r in readers:
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r.join(timeout=5)
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# No assertion needed - test passes if no exceptions/deadlocks
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# Start execution in a thread, interrupt after 0.5s
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result_holder = {"value": None}
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def _run():
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result_holder["value"] = env.execute(
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"trap '' TERM; sleep 60",
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timeout=30,
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)
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class TestInterruptibleContext:
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"""Test InterruptibleContext helper."""
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def test_context_manager(self):
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"""Test context manager basic usage."""
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set_interrupt(False)
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with InterruptibleContext() as ctx:
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for _ in range(10):
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assert ctx.should_continue() is True
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assert is_interrupted() is False
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def test_context_respects_interrupt(self):
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"""Test that context stops on interrupt."""
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set_interrupt(False)
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with InterruptibleContext(check_interval=5) as ctx:
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# Simulate work
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for i in range(20):
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if i == 10:
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set_interrupt(True)
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if not ctx.should_continue():
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break
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# Should have been interrupted
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assert is_interrupted() is True
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set_interrupt(False) # Cleanup
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t = threading.Thread(target=_run)
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class TestWaitForInterrupt:
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"""Test wait_for_interrupt functionality."""
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def test_wait_with_timeout(self):
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"""Test wait returns False on timeout."""
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set_interrupt(False)
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start = time.time()
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result = wait_for_interrupt(timeout=0.1)
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elapsed = time.time() - start
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assert result is False
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assert elapsed < 0.5 # Should not hang
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def test_wait_interruptible(self):
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"""Test wait returns True when interrupted."""
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set_interrupt(False)
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def delayed_interrupt():
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time.sleep(0.1)
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set_interrupt(True)
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t = threading.Thread(target=delayed_interrupt)
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t.start()
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time.sleep(0.5)
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set_interrupt(True)
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start = time.time()
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result = wait_for_interrupt(timeout=5.0)
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elapsed = time.time() - start
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t.join(timeout=5)
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set_interrupt(False)
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assert result_holder["value"] is not None
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assert result_holder["value"]["returncode"] == 130
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assert "interrupted" in result_holder["value"]["output"].lower()
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# ---------------------------------------------------------------------------
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# Manual smoke test checklist (not automated)
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# ---------------------------------------------------------------------------
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SMOKE_TESTS = """
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Manual Smoke Test Checklist:
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1. CLI: Run `hermes`, ask it to `sleep 30` in terminal, type "stop" + Enter.
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Expected: command dies within 2s, agent responds to "stop".
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2. CLI: Ask it to extract content from 5 URLs, type interrupt mid-way.
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Expected: remaining URLs are skipped, partial results returned.
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3. Gateway (Telegram): Send a long task, then send "Stop".
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Expected: agent stops and responds acknowledging the stop.
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4. Gateway (Telegram): Send "Stop" then "Do X instead" rapidly.
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Expected: both messages appear as the next prompt (joined by newline).
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5. CLI: Start a task that generates 3+ tool calls in one batch.
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Type interrupt during the first tool call.
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Expected: only 1 tool executes, remaining are skipped.
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"""
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assert result is True
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assert elapsed < 1.0 # Should return quickly after interrupt
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set_interrupt(False) # Cleanup
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@@ -4,6 +4,9 @@ Provides a global threading.Event that any tool can check to determine
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if the user has requested an interrupt. The agent's interrupt() method
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sets this event, and tools poll it during long-running operations.
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SECURITY FIX (V-007): Added proper locking to prevent race conditions
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in interrupt propagation. Uses RLock for thread-safe nested access.
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Usage in tools:
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from tools.interrupt import is_interrupted
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if is_interrupted():
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@@ -12,17 +15,79 @@ Usage in tools:
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import threading
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# Global interrupt event with proper synchronization
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_interrupt_event = threading.Event()
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_interrupt_lock = threading.RLock()
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_interrupt_count = 0 # Track nested interrupts for idempotency
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def set_interrupt(active: bool) -> None:
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"""Called by the agent to signal or clear the interrupt."""
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if active:
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_interrupt_event.set()
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else:
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_interrupt_event.clear()
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"""Called by the agent to signal or clear the interrupt.
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SECURITY FIX: Uses RLock to prevent race conditions when multiple
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threads attempt to set/clear the interrupt simultaneously.
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"""
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global _interrupt_count
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with _interrupt_lock:
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if active:
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_interrupt_count += 1
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_interrupt_event.set()
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else:
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_interrupt_count = 0
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_interrupt_event.clear()
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def is_interrupted() -> bool:
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"""Check if an interrupt has been requested. Safe to call from any thread."""
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return _interrupt_event.is_set()
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def get_interrupt_count() -> int:
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"""Get the current interrupt nesting count (for debugging).
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Returns the number of times set_interrupt(True) has been called
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without a corresponding clear.
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"""
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with _interrupt_lock:
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return _interrupt_count
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def wait_for_interrupt(timeout: float = None) -> bool:
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"""Block until interrupt is set or timeout expires.
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Args:
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timeout: Maximum time to wait in seconds
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Returns:
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True if interrupt was set, False if timeout expired
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"""
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return _interrupt_event.wait(timeout)
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class InterruptibleContext:
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"""Context manager for interruptible operations.
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Usage:
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with InterruptibleContext() as ctx:
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while ctx.should_continue():
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do_work()
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"""
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def __init__(self, check_interval: int = 100):
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self.check_interval = check_interval
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self._iteration = 0
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self._interrupted = False
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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pass
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def should_continue(self) -> bool:
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"""Check if operation should continue (not interrupted)."""
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self._iteration += 1
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if self._iteration % self.check_interval == 0:
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self._interrupted = is_interrupted()
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return not self._interrupted
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@@ -47,7 +47,8 @@ logger = logging.getLogger(__name__)
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# The terminal tool polls this during command execution so it can kill
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# long-running subprocesses immediately instead of blocking until timeout.
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# ---------------------------------------------------------------------------
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from tools.interrupt import is_interrupted, _interrupt_event # noqa: F401 — re-exported
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from tools.interrupt import is_interrupted # noqa: F401 — re-exported
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# SECURITY: Don't expose _interrupt_event directly - use proper API
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# display_hermes_home imported lazily at call site (stale-module safety during hermes update)
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||||
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Block a user