from contextlib import contextmanager import datetime import faulthandler import os import re import signal import subprocess import sys from test import support from test.support import os_helper from test.support import script_helper, is_android from test.support import skip_if_sanitizer import tempfile import unittest from textwrap import dedent try: import _testcapi except ImportError: _testcapi = None if not support.has_subprocess_support: raise unittest.SkipTest("test module requires subprocess") TIMEOUT = 0.5 MS_WINDOWS = (os.name == 'nt') def expected_traceback(lineno1, lineno2, header, min_count=1): regex = header regex += ' File "", line %s in func\n' % lineno1 regex += ' File "", line %s in ' % lineno2 if 1 < min_count: return '^' + (regex + '\n') * (min_count - 1) + regex else: return '^' + regex + '$' def skip_segfault_on_android(test): # Issue #32138: Raising SIGSEGV on Android may not cause a crash. return unittest.skipIf(is_android, 'raising SIGSEGV on Android is unreliable')(test) @contextmanager def temporary_filename(): filename = tempfile.mktemp() try: yield filename finally: os_helper.unlink(filename) class FaultHandlerTests(unittest.TestCase): def get_output(self, code, filename=None, fd=None): """ Run the specified code in Python (in a new child process) and read the output from the standard error or from a file (if filename is set). Return the output lines as a list. Strip the reference count from the standard error for Python debug build, and replace "Current thread 0x00007f8d8fbd9700" by "Current thread XXX". """ code = dedent(code).strip() pass_fds = [] if fd is not None: pass_fds.append(fd) with support.SuppressCrashReport(): process = script_helper.spawn_python('-c', code, pass_fds=pass_fds) with process: output, stderr = process.communicate() exitcode = process.wait() output = output.decode('ascii', 'backslashreplace') if filename: self.assertEqual(output, '') with open(filename, "rb") as fp: output = fp.read() output = output.decode('ascii', 'backslashreplace') elif fd is not None: self.assertEqual(output, '') os.lseek(fd, os.SEEK_SET, 0) with open(fd, "rb", closefd=False) as fp: output = fp.read() output = output.decode('ascii', 'backslashreplace') return output.splitlines(), exitcode def check_error(self, code, lineno, fatal_error, *, filename=None, all_threads=True, other_regex=None, fd=None, know_current_thread=True, py_fatal_error=False, garbage_collecting=False, function=''): """ Check that the fault handler for fatal errors is enabled and check the traceback from the child process output. Raise an error if the output doesn't match the expected format. """ if all_threads: if know_current_thread: header = 'Current thread 0x[0-9a-f]+' else: header = 'Thread 0x[0-9a-f]+' else: header = 'Stack' regex = [f'^{fatal_error}'] if py_fatal_error: regex.append("Python runtime state: initialized") regex.append('') regex.append(fr'{header} \(most recent call first\):') if garbage_collecting: regex.append(' Garbage-collecting') regex.append(fr' File "", line {lineno} in {function}') regex = '\n'.join(regex) if other_regex: regex = f'(?:{regex}|{other_regex})' # Enable MULTILINE flag regex = f'(?m){regex}' output, exitcode = self.get_output(code, filename=filename, fd=fd) output = '\n'.join(output) self.assertRegex(output, regex) self.assertNotEqual(exitcode, 0) def check_fatal_error(self, code, line_number, name_regex, func=None, **kw): if func: name_regex = '%s: %s' % (func, name_regex) fatal_error = 'Fatal Python error: %s' % name_regex self.check_error(code, line_number, fatal_error, **kw) def check_windows_exception(self, code, line_number, name_regex, **kw): fatal_error = 'Windows fatal exception: %s' % name_regex self.check_error(code, line_number, fatal_error, **kw) @unittest.skipIf(sys.platform.startswith('aix'), "the first page of memory is a mapped read-only on AIX") def test_read_null(self): if not MS_WINDOWS: self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._read_null() """, 3, # Issue #12700: Read NULL raises SIGILL on Mac OS X Lion '(?:Segmentation fault' '|Bus error' '|Illegal instruction)') else: self.check_windows_exception(""" import faulthandler faulthandler.enable() faulthandler._read_null() """, 3, 'access violation') @skip_segfault_on_android def test_sigsegv(self): self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._sigsegv() """, 3, 'Segmentation fault') @skip_segfault_on_android def test_gc(self): # bpo-44466: Detect if the GC is running self.check_fatal_error(""" import faulthandler import gc import sys faulthandler.enable() class RefCycle: def __del__(self): faulthandler._sigsegv() # create a reference cycle which triggers a fatal # error in a destructor a = RefCycle() b = RefCycle() a.b = b b.a = a # Delete the objects, not the cycle a = None b = None # Break the reference cycle: call __del__() gc.collect() # Should not reach this line print("exit", file=sys.stderr) """, 9, 'Segmentation fault', function='__del__', garbage_collecting=True) def test_fatal_error_c_thread(self): self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._fatal_error_c_thread() """, 3, 'in new thread', know_current_thread=False, func='faulthandler_fatal_error_thread', py_fatal_error=True) def test_sigabrt(self): self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._sigabrt() """, 3, 'Aborted') @unittest.skipIf(sys.platform == 'win32', "SIGFPE cannot be caught on Windows") def test_sigfpe(self): self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._sigfpe() """, 3, 'Floating point exception') @unittest.skipIf(_testcapi is None, 'need _testcapi') @unittest.skipUnless(hasattr(signal, 'SIGBUS'), 'need signal.SIGBUS') @skip_segfault_on_android def test_sigbus(self): self.check_fatal_error(""" import faulthandler import signal faulthandler.enable() signal.raise_signal(signal.SIGBUS) """, 5, 'Bus error') @unittest.skipIf(_testcapi is None, 'need _testcapi') @unittest.skipUnless(hasattr(signal, 'SIGILL'), 'need signal.SIGILL') @skip_segfault_on_android def test_sigill(self): self.check_fatal_error(""" import faulthandler import signal faulthandler.enable() signal.raise_signal(signal.SIGILL) """, 5, 'Illegal instruction') def check_fatal_error_func(self, release_gil): # Test that Py_FatalError() dumps a traceback with support.SuppressCrashReport(): self.check_fatal_error(f""" import _testcapi _testcapi.fatal_error(b'xyz', {release_gil}) """, 2, 'xyz', func='_testcapi_fatal_error_impl', py_fatal_error=True) def test_fatal_error(self): self.check_fatal_error_func(False) def test_fatal_error_without_gil(self): self.check_fatal_error_func(True) @unittest.skipIf(sys.platform.startswith('openbsd'), "Issue #12868: sigaltstack() doesn't work on " "OpenBSD if Python is compiled with pthread") @unittest.skipIf(not hasattr(faulthandler, '_stack_overflow'), 'need faulthandler._stack_overflow()') def test_stack_overflow(self): self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._stack_overflow() """, 3, '(?:Segmentation fault|Bus error)', other_regex='unable to raise a stack overflow') @skip_segfault_on_android def test_gil_released(self): self.check_fatal_error(""" import faulthandler faulthandler.enable() faulthandler._sigsegv(True) """, 3, 'Segmentation fault') @skip_if_sanitizer(memory=True, ub=True, reason="sanitizer " "builds change crashing process output.") @skip_segfault_on_android def test_enable_file(self): with temporary_filename() as filename: self.check_fatal_error(""" import faulthandler output = open({filename}, 'wb') faulthandler.enable(output) faulthandler._sigsegv() """.format(filename=repr(filename)), 4, 'Segmentation fault', filename=filename) @unittest.skipIf(sys.platform == "win32", "subprocess doesn't support pass_fds on Windows") @skip_if_sanitizer(memory=True, ub=True, reason="sanitizer " "builds change crashing process output.") @skip_segfault_on_android def test_enable_fd(self): with tempfile.TemporaryFile('wb+') as fp: fd = fp.fileno() self.check_fatal_error(""" import faulthandler import sys faulthandler.enable(%s) faulthandler._sigsegv() """ % fd, 4, 'Segmentation fault', fd=fd) @skip_segfault_on_android def test_enable_single_thread(self): self.check_fatal_error(""" import faulthandler faulthandler.enable(all_threads=False) faulthandler._sigsegv() """, 3, 'Segmentation fault', all_threads=False) @skip_segfault_on_android def test_disable(self): code = """ import faulthandler faulthandler.enable() faulthandler.disable() faulthandler._sigsegv() """ not_expected = 'Fatal Python error' stderr, exitcode = self.get_output(code) stderr = '\n'.join(stderr) self.assertTrue(not_expected not in stderr, "%r is present in %r" % (not_expected, stderr)) self.assertNotEqual(exitcode, 0) @skip_segfault_on_android def test_dump_ext_modules(self): code = """ import faulthandler import sys # Don't filter stdlib module names sys.stdlib_module_names = frozenset() faulthandler.enable() faulthandler._sigsegv() """ stderr, exitcode = self.get_output(code) stderr = '\n'.join(stderr) match = re.search(r'^Extension modules:(.*) \(total: [0-9]+\)$', stderr, re.MULTILINE) if not match: self.fail(f"Cannot find 'Extension modules:' in {stderr!r}") modules = set(match.group(1).strip().split(', ')) for name in ('sys', 'faulthandler'): self.assertIn(name, modules) def test_is_enabled(self): orig_stderr = sys.stderr try: # regrtest may replace sys.stderr by io.StringIO object, but # faulthandler.enable() requires that sys.stderr has a fileno() # method sys.stderr = sys.__stderr__ was_enabled = faulthandler.is_enabled() try: faulthandler.enable() self.assertTrue(faulthandler.is_enabled()) faulthandler.disable() self.assertFalse(faulthandler.is_enabled()) finally: if was_enabled: faulthandler.enable() else: faulthandler.disable() finally: sys.stderr = orig_stderr @support.requires_subprocess() def test_disabled_by_default(self): # By default, the module should be disabled code = "import faulthandler; print(faulthandler.is_enabled())" args = (sys.executable, "-E", "-c", code) # don't use assert_python_ok() because it always enables faulthandler output = subprocess.check_output(args) self.assertEqual(output.rstrip(), b"False") @support.requires_subprocess() def test_sys_xoptions(self): # Test python -X faulthandler code = "import faulthandler; print(faulthandler.is_enabled())" args = filter(None, (sys.executable, "-E" if sys.flags.ignore_environment else "", "-X", "faulthandler", "-c", code)) env = os.environ.copy() env.pop("PYTHONFAULTHANDLER", None) # don't use assert_python_ok() because it always enables faulthandler output = subprocess.check_output(args, env=env) self.assertEqual(output.rstrip(), b"True") @support.requires_subprocess() def test_env_var(self): # empty env var code = "import faulthandler; print(faulthandler.is_enabled())" args = (sys.executable, "-c", code) env = dict(os.environ) env['PYTHONFAULTHANDLER'] = '' env['PYTHONDEVMODE'] = '' # don't use assert_python_ok() because it always enables faulthandler output = subprocess.check_output(args, env=env) self.assertEqual(output.rstrip(), b"False") # non-empty env var env = dict(os.environ) env['PYTHONFAULTHANDLER'] = '1' env['PYTHONDEVMODE'] = '' output = subprocess.check_output(args, env=env) self.assertEqual(output.rstrip(), b"True") def check_dump_traceback(self, *, filename=None, fd=None): """ Explicitly call dump_traceback() function and check its output. Raise an error if the output doesn't match the expected format. """ code = """ import faulthandler filename = {filename!r} fd = {fd} def funcB(): if filename: with open(filename, "wb") as fp: faulthandler.dump_traceback(fp, all_threads=False) elif fd is not None: faulthandler.dump_traceback(fd, all_threads=False) else: faulthandler.dump_traceback(all_threads=False) def funcA(): funcB() funcA() """ code = code.format( filename=filename, fd=fd, ) if filename: lineno = 9 elif fd is not None: lineno = 11 else: lineno = 14 expected = [ 'Stack (most recent call first):', ' File "", line %s in funcB' % lineno, ' File "", line 17 in funcA', ' File "", line 19 in ' ] trace, exitcode = self.get_output(code, filename, fd) self.assertEqual(trace, expected) self.assertEqual(exitcode, 0) def test_dump_traceback(self): self.check_dump_traceback() def test_dump_traceback_file(self): with temporary_filename() as filename: self.check_dump_traceback(filename=filename) @unittest.skipIf(sys.platform == "win32", "subprocess doesn't support pass_fds on Windows") def test_dump_traceback_fd(self): with tempfile.TemporaryFile('wb+') as fp: self.check_dump_traceback(fd=fp.fileno()) def test_truncate(self): maxlen = 500 func_name = 'x' * (maxlen + 50) truncated = 'x' * maxlen + '...' code = """ import faulthandler def {func_name}(): faulthandler.dump_traceback(all_threads=False) {func_name}() """ code = code.format( func_name=func_name, ) expected = [ 'Stack (most recent call first):', ' File "", line 4 in %s' % truncated, ' File "", line 6 in ' ] trace, exitcode = self.get_output(code) self.assertEqual(trace, expected) self.assertEqual(exitcode, 0) def check_dump_traceback_threads(self, filename): """ Call explicitly dump_traceback(all_threads=True) and check the output. Raise an error if the output doesn't match the expected format. """ code = """ import faulthandler from threading import Thread, Event import time def dump(): if {filename}: with open({filename}, "wb") as fp: faulthandler.dump_traceback(fp, all_threads=True) else: faulthandler.dump_traceback(all_threads=True) class Waiter(Thread): # avoid blocking if the main thread raises an exception. daemon = True def __init__(self): Thread.__init__(self) self.running = Event() self.stop = Event() def run(self): self.running.set() self.stop.wait() waiter = Waiter() waiter.start() waiter.running.wait() dump() waiter.stop.set() waiter.join() """ code = code.format(filename=repr(filename)) output, exitcode = self.get_output(code, filename) output = '\n'.join(output) if filename: lineno = 8 else: lineno = 10 regex = r""" ^Thread 0x[0-9a-f]+ \(most recent call first\): (?: File ".*threading.py", line [0-9]+ in [_a-z]+ ){{1,3}} File "", line 23 in run File ".*threading.py", line [0-9]+ in _bootstrap_inner File ".*threading.py", line [0-9]+ in _bootstrap Current thread 0x[0-9a-f]+ \(most recent call first\): File "", line {lineno} in dump File "", line 28 in $ """ regex = dedent(regex.format(lineno=lineno)).strip() self.assertRegex(output, regex) self.assertEqual(exitcode, 0) def test_dump_traceback_threads(self): self.check_dump_traceback_threads(None) def test_dump_traceback_threads_file(self): with temporary_filename() as filename: self.check_dump_traceback_threads(filename) def check_dump_traceback_later(self, repeat=False, cancel=False, loops=1, *, filename=None, fd=None): """ Check how many times the traceback is written in timeout x 2.5 seconds, or timeout x 3.5 seconds if cancel is True: 1, 2 or 3 times depending on repeat and cancel options. Raise an error if the output doesn't match the expect format. """ timeout_str = str(datetime.timedelta(seconds=TIMEOUT)) code = """ import faulthandler import time import sys timeout = {timeout} repeat = {repeat} cancel = {cancel} loops = {loops} filename = {filename!r} fd = {fd} def func(timeout, repeat, cancel, file, loops): for loop in range(loops): faulthandler.dump_traceback_later(timeout, repeat=repeat, file=file) if cancel: faulthandler.cancel_dump_traceback_later() time.sleep(timeout * 5) faulthandler.cancel_dump_traceback_later() if filename: file = open(filename, "wb") elif fd is not None: file = sys.stderr.fileno() else: file = None func(timeout, repeat, cancel, file, loops) if filename: file.close() """ code = code.format( timeout=TIMEOUT, repeat=repeat, cancel=cancel, loops=loops, filename=filename, fd=fd, ) trace, exitcode = self.get_output(code, filename) trace = '\n'.join(trace) if not cancel: count = loops if repeat: count *= 2 header = r'Timeout \(%s\)!\nThread 0x[0-9a-f]+ \(most recent call first\):\n' % timeout_str regex = expected_traceback(17, 26, header, min_count=count) self.assertRegex(trace, regex) else: self.assertEqual(trace, '') self.assertEqual(exitcode, 0) def test_dump_traceback_later(self): self.check_dump_traceback_later() def test_dump_traceback_later_repeat(self): self.check_dump_traceback_later(repeat=True) def test_dump_traceback_later_cancel(self): self.check_dump_traceback_later(cancel=True) def test_dump_traceback_later_file(self): with temporary_filename() as filename: self.check_dump_traceback_later(filename=filename) @unittest.skipIf(sys.platform == "win32", "subprocess doesn't support pass_fds on Windows") def test_dump_traceback_later_fd(self): with tempfile.TemporaryFile('wb+') as fp: self.check_dump_traceback_later(fd=fp.fileno()) def test_dump_traceback_later_twice(self): self.check_dump_traceback_later(loops=2) @unittest.skipIf(not hasattr(faulthandler, "register"), "need faulthandler.register") def check_register(self, filename=False, all_threads=False, unregister=False, chain=False, fd=None): """ Register a handler displaying the traceback on a user signal. Raise the signal and check the written traceback. If chain is True, check that the previous signal handler is called. Raise an error if the output doesn't match the expected format. """ signum = signal.SIGUSR1 code = """ import faulthandler import os import signal import sys all_threads = {all_threads} signum = {signum:d} unregister = {unregister} chain = {chain} filename = {filename!r} fd = {fd} def func(signum): os.kill(os.getpid(), signum) def handler(signum, frame): handler.called = True handler.called = False if filename: file = open(filename, "wb") elif fd is not None: file = sys.stderr.fileno() else: file = None if chain: signal.signal(signum, handler) faulthandler.register(signum, file=file, all_threads=all_threads, chain={chain}) if unregister: faulthandler.unregister(signum) func(signum) if chain and not handler.called: if file is not None: output = file else: output = sys.stderr print("Error: signal handler not called!", file=output) exitcode = 1 else: exitcode = 0 if filename: file.close() sys.exit(exitcode) """ code = code.format( all_threads=all_threads, signum=signum, unregister=unregister, chain=chain, filename=filename, fd=fd, ) trace, exitcode = self.get_output(code, filename) trace = '\n'.join(trace) if not unregister: if all_threads: regex = r'Current thread 0x[0-9a-f]+ \(most recent call first\):\n' else: regex = r'Stack \(most recent call first\):\n' regex = expected_traceback(14, 32, regex) self.assertRegex(trace, regex) else: self.assertEqual(trace, '') if unregister: self.assertNotEqual(exitcode, 0) else: self.assertEqual(exitcode, 0) def test_register(self): self.check_register() def test_unregister(self): self.check_register(unregister=True) def test_register_file(self): with temporary_filename() as filename: self.check_register(filename=filename) @unittest.skipIf(sys.platform == "win32", "subprocess doesn't support pass_fds on Windows") def test_register_fd(self): with tempfile.TemporaryFile('wb+') as fp: self.check_register(fd=fp.fileno()) def test_register_threads(self): self.check_register(all_threads=True) def test_register_chain(self): self.check_register(chain=True) @contextmanager def check_stderr_none(self): stderr = sys.stderr try: sys.stderr = None with self.assertRaises(RuntimeError) as cm: yield self.assertEqual(str(cm.exception), "sys.stderr is None") finally: sys.stderr = stderr def test_stderr_None(self): # Issue #21497: provide a helpful error if sys.stderr is None, # instead of just an attribute error: "None has no attribute fileno". with self.check_stderr_none(): faulthandler.enable() with self.check_stderr_none(): faulthandler.dump_traceback() with self.check_stderr_none(): faulthandler.dump_traceback_later(1e-3) if hasattr(faulthandler, "register"): with self.check_stderr_none(): faulthandler.register(signal.SIGUSR1) @unittest.skipUnless(MS_WINDOWS, 'specific to Windows') def test_raise_exception(self): for exc, name in ( ('EXCEPTION_ACCESS_VIOLATION', 'access violation'), ('EXCEPTION_INT_DIVIDE_BY_ZERO', 'int divide by zero'), ('EXCEPTION_STACK_OVERFLOW', 'stack overflow'), ): self.check_windows_exception(f""" import faulthandler faulthandler.enable() faulthandler._raise_exception(faulthandler._{exc}) """, 3, name) @unittest.skipUnless(MS_WINDOWS, 'specific to Windows') def test_ignore_exception(self): for exc_code in ( 0xE06D7363, # MSC exception ("Emsc") 0xE0434352, # COM Callable Runtime exception ("ECCR") ): code = f""" import faulthandler faulthandler.enable() faulthandler._raise_exception({exc_code}) """ code = dedent(code) output, exitcode = self.get_output(code) self.assertEqual(output, []) self.assertEqual(exitcode, exc_code) @unittest.skipUnless(MS_WINDOWS, 'specific to Windows') def test_raise_nonfatal_exception(self): # These exceptions are not strictly errors. Letting # faulthandler display the traceback when they are # raised is likely to result in noise. However, they # may still terminate the process if there is no # handler installed for them (which there typically # is, e.g. for debug messages). for exc in ( 0x00000000, 0x34567890, 0x40000000, 0x40001000, 0x70000000, 0x7FFFFFFF, ): output, exitcode = self.get_output(f""" import faulthandler faulthandler.enable() faulthandler._raise_exception(0x{exc:x}) """ ) self.assertEqual(output, []) # On Windows older than 7 SP1, the actual exception code has # bit 29 cleared. self.assertIn(exitcode, (exc, exc & ~0x10000000)) @unittest.skipUnless(MS_WINDOWS, 'specific to Windows') def test_disable_windows_exc_handler(self): code = dedent(""" import faulthandler faulthandler.enable() faulthandler.disable() code = faulthandler._EXCEPTION_ACCESS_VIOLATION faulthandler._raise_exception(code) """) output, exitcode = self.get_output(code) self.assertEqual(output, []) self.assertEqual(exitcode, 0xC0000005) def test_cancel_later_without_dump_traceback_later(self): # bpo-37933: Calling cancel_dump_traceback_later() # without dump_traceback_later() must not segfault. code = dedent(""" import faulthandler faulthandler.cancel_dump_traceback_later() """) output, exitcode = self.get_output(code) self.assertEqual(output, []) self.assertEqual(exitcode, 0) if __name__ == "__main__": unittest.main()