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Diffstat (limited to 'Lib/test/test_gdb/util.py')
| -rw-r--r-- | Lib/test/test_gdb/util.py | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/Lib/test/test_gdb/util.py b/Lib/test/test_gdb/util.py new file mode 100644 index 0000000..30beb4e --- /dev/null +++ b/Lib/test/test_gdb/util.py @@ -0,0 +1,304 @@ +import os +import re +import subprocess +import sys +import sysconfig +import unittest +from test import support + + +MS_WINDOWS = (sys.platform == 'win32') +if MS_WINDOWS: + raise unittest.SkipTest("test_gdb doesn't work on Windows") + + +def get_gdb_version(): + try: + cmd = ["gdb", "-nx", "--version"] + proc = subprocess.Popen(cmd, + stdout=subprocess.PIPE, + stderr=subprocess.PIPE, + universal_newlines=True) + with proc: + version, stderr = proc.communicate() + + if proc.returncode: + raise Exception(f"Command {' '.join(cmd)!r} failed " + f"with exit code {proc.returncode}: " + f"stdout={version!r} stderr={stderr!r}") + except OSError: + # This is what "no gdb" looks like. There may, however, be other + # errors that manifest this way too. + raise unittest.SkipTest("Couldn't find gdb on the path") + + # Regex to parse: + # 'GNU gdb (GDB; SUSE Linux Enterprise 12) 7.7\n' -> 7.7 + # 'GNU gdb (GDB) Fedora 7.9.1-17.fc22\n' -> 7.9 + # 'GNU gdb 6.1.1 [FreeBSD]\n' -> 6.1 + # 'GNU gdb (GDB) Fedora (7.5.1-37.fc18)\n' -> 7.5 + # 'HP gdb 6.7 for HP Itanium (32 or 64 bit) and target HP-UX 11iv2 and 11iv3.\n' -> 6.7 + match = re.search(r"^(?:GNU|HP) gdb.*?\b(\d+)\.(\d+)", version) + if match is None: + raise Exception("unable to parse GDB version: %r" % version) + return (version, int(match.group(1)), int(match.group(2))) + +gdb_version, gdb_major_version, gdb_minor_version = get_gdb_version() +if gdb_major_version < 7: + raise unittest.SkipTest("gdb versions before 7.0 didn't support python " + "embedding. Saw %s.%s:\n%s" + % (gdb_major_version, gdb_minor_version, + gdb_version)) + +if not sysconfig.is_python_build(): + raise unittest.SkipTest("test_gdb only works on source builds at the moment.") + +if ((sysconfig.get_config_var('PGO_PROF_USE_FLAG') or 'xxx') in + (sysconfig.get_config_var('PY_CORE_CFLAGS') or '')): + raise unittest.SkipTest("test_gdb is not reliable on PGO builds") + +# Location of custom hooks file in a repository checkout. +checkout_hook_path = os.path.join(os.path.dirname(sys.executable), + 'python-gdb.py') + +PYTHONHASHSEED = '123' + + +def cet_protection(): + cflags = sysconfig.get_config_var('CFLAGS') + if not cflags: + return False + flags = cflags.split() + # True if "-mcet -fcf-protection" options are found, but false + # if "-fcf-protection=none" or "-fcf-protection=return" is found. + return (('-mcet' in flags) + and any((flag.startswith('-fcf-protection') + and not flag.endswith(("=none", "=return"))) + for flag in flags)) + +# Control-flow enforcement technology +CET_PROTECTION = cet_protection() + + +def run_gdb(*args, **env_vars): + """Runs gdb in --batch mode with the additional arguments given by *args. + + Returns its (stdout, stderr) decoded from utf-8 using the replace handler. + """ + if env_vars: + env = os.environ.copy() + env.update(env_vars) + else: + env = None + # -nx: Do not execute commands from any .gdbinit initialization files + # (issue #22188) + base_cmd = ('gdb', '--batch', '-nx') + if (gdb_major_version, gdb_minor_version) >= (7, 4): + base_cmd += ('-iex', 'add-auto-load-safe-path ' + checkout_hook_path) + proc = subprocess.Popen(base_cmd + args, + # Redirect stdin to prevent GDB from messing with + # the terminal settings + stdin=subprocess.PIPE, + stdout=subprocess.PIPE, + stderr=subprocess.PIPE, + env=env) + with proc: + out, err = proc.communicate() + return out.decode('utf-8', 'replace'), err.decode('utf-8', 'replace') + +# Verify that "gdb" was built with the embedded python support enabled: +gdbpy_version, _ = run_gdb("--eval-command=python import sys; print(sys.version_info)") +if not gdbpy_version: + raise unittest.SkipTest("gdb not built with embedded python support") + +if "major=2" in gdbpy_version: + raise unittest.SkipTest("gdb built with Python 2") + +# Verify that "gdb" can load our custom hooks, as OS security settings may +# disallow this without a customized .gdbinit. +_, gdbpy_errors = run_gdb('--args', sys.executable) +if "auto-loading has been declined" in gdbpy_errors: + msg = "gdb security settings prevent use of custom hooks: " + raise unittest.SkipTest(msg + gdbpy_errors.rstrip()) + +BREAKPOINT_FN='builtin_id' + + +def setup_module(): + if support.verbose: + print("GDB version %s.%s:" % (gdb_major_version, gdb_minor_version)) + for line in gdb_version.splitlines(): + print(" " * 4 + line) + + +@unittest.skipIf(support.PGO, "not useful for PGO") +class DebuggerTests(unittest.TestCase): + + """Test that the debugger can debug Python.""" + + def get_stack_trace(self, source=None, script=None, + breakpoint=BREAKPOINT_FN, + cmds_after_breakpoint=None, + import_site=False, + ignore_stderr=False): + ''' + Run 'python -c SOURCE' under gdb with a breakpoint. + + Support injecting commands after the breakpoint is reached + + Returns the stdout from gdb + + cmds_after_breakpoint: if provided, a list of strings: gdb commands + ''' + # We use "set breakpoint pending yes" to avoid blocking with a: + # Function "foo" not defined. + # Make breakpoint pending on future shared library load? (y or [n]) + # error, which typically happens python is dynamically linked (the + # breakpoints of interest are to be found in the shared library) + # When this happens, we still get: + # Function "textiowrapper_write" not defined. + # emitted to stderr each time, alas. + + # Initially I had "--eval-command=continue" here, but removed it to + # avoid repeated print breakpoints when traversing hierarchical data + # structures + + # Generate a list of commands in gdb's language: + commands = ['set breakpoint pending yes', + 'break %s' % breakpoint, + + # The tests assume that the first frame of printed + # backtrace will not contain program counter, + # that is however not guaranteed by gdb + # therefore we need to use 'set print address off' to + # make sure the counter is not there. For example: + # #0 in PyObject_Print ... + # is assumed, but sometimes this can be e.g. + # #0 0x00003fffb7dd1798 in PyObject_Print ... + 'set print address off', + + 'run'] + + # GDB as of 7.4 onwards can distinguish between the + # value of a variable at entry vs current value: + # http://sourceware.org/gdb/onlinedocs/gdb/Variables.html + # which leads to the selftests failing with errors like this: + # AssertionError: 'v@entry=()' != '()' + # Disable this: + if (gdb_major_version, gdb_minor_version) >= (7, 4): + commands += ['set print entry-values no'] + + if cmds_after_breakpoint: + if CET_PROTECTION: + # bpo-32962: When Python is compiled with -mcet + # -fcf-protection, function arguments are unusable before + # running the first instruction of the function entry point. + # The 'next' command makes the required first step. + commands += ['next'] + commands += cmds_after_breakpoint + else: + commands += ['backtrace'] + + # print commands + + # Use "commands" to generate the arguments with which to invoke "gdb": + args = ['--eval-command=%s' % cmd for cmd in commands] + args += ["--args", + sys.executable] + args.extend(subprocess._args_from_interpreter_flags()) + + if not import_site: + # -S suppresses the default 'import site' + args += ["-S"] + + if source: + args += ["-c", source] + elif script: + args += [script] + + # Use "args" to invoke gdb, capturing stdout, stderr: + out, err = run_gdb(*args, PYTHONHASHSEED=PYTHONHASHSEED) + + if not ignore_stderr: + for line in err.splitlines(): + print(line, file=sys.stderr) + + # bpo-34007: Sometimes some versions of the shared libraries that + # are part of the traceback are compiled in optimised mode and the + # Program Counter (PC) is not present, not allowing gdb to walk the + # frames back. When this happens, the Python bindings of gdb raise + # an exception, making the test impossible to succeed. + if "PC not saved" in err: + raise unittest.SkipTest("gdb cannot walk the frame object" + " because the Program Counter is" + " not present") + + # bpo-40019: Skip the test if gdb failed to read debug information + # because the Python binary is optimized. + for pattern in ( + '(frame information optimized out)', + 'Unable to read information on python frame', + # gh-91960: On Python built with "clang -Og", gdb gets + # "frame=<optimized out>" for _PyEval_EvalFrameDefault() parameter + '(unable to read python frame information)', + # gh-104736: On Python built with "clang -Og" on ppc64le, + # "py-bt" displays a truncated or not traceback, but "where" + # logs this error message: + 'Backtrace stopped: frame did not save the PC', + # gh-104736: When "bt" command displays something like: + # "#1 0x0000000000000000 in ?? ()", the traceback is likely + # truncated or wrong. + ' ?? ()', + ): + if pattern in out: + raise unittest.SkipTest(f"{pattern!r} found in gdb output") + + return out + + def get_gdb_repr(self, source, + cmds_after_breakpoint=None, + import_site=False): + # Given an input python source representation of data, + # run "python -c'id(DATA)'" under gdb with a breakpoint on + # builtin_id and scrape out gdb's representation of the "op" + # parameter, and verify that the gdb displays the same string + # + # Verify that the gdb displays the expected string + # + # For a nested structure, the first time we hit the breakpoint will + # give us the top-level structure + + # NOTE: avoid decoding too much of the traceback as some + # undecodable characters may lurk there in optimized mode + # (issue #19743). + cmds_after_breakpoint = cmds_after_breakpoint or ["backtrace 1"] + gdb_output = self.get_stack_trace(source, breakpoint=BREAKPOINT_FN, + cmds_after_breakpoint=cmds_after_breakpoint, + import_site=import_site) + # gdb can insert additional '\n' and space characters in various places + # in its output, depending on the width of the terminal it's connected + # to (using its "wrap_here" function) + m = re.search( + # Match '#0 builtin_id(self=..., v=...)' + r'#0\s+builtin_id\s+\(self\=.*,\s+v=\s*(.*?)?\)' + # Match ' at Python/bltinmodule.c'. + # bpo-38239: builtin_id() is defined in Python/bltinmodule.c, + # but accept any "Directory\file.c" to support Link Time + # Optimization (LTO). + r'\s+at\s+\S*[A-Za-z]+/[A-Za-z0-9_-]+\.c', + gdb_output, re.DOTALL) + if not m: + self.fail('Unexpected gdb output: %r\n%s' % (gdb_output, gdb_output)) + return m.group(1), gdb_output + + def assertEndsWith(self, actual, exp_end): + '''Ensure that the given "actual" string ends with "exp_end"''' + self.assertTrue(actual.endswith(exp_end), + msg='%r did not end with %r' % (actual, exp_end)) + + def assertMultilineMatches(self, actual, pattern): + m = re.match(pattern, actual, re.DOTALL) + if not m: + self.fail(msg='%r did not match %r' % (actual, pattern)) + + def get_sample_script(self): + return os.path.join(os.path.dirname(__file__), 'gdb_sample.py') |