| #!/usr/bin/env python |
| """Calls C-Reduce to create a minimal reproducer for clang crashes. |
| |
| Output files: |
| *.reduced.sh -- crash reproducer with minimal arguments |
| *.reduced.cpp -- the reduced file |
| *.test.sh -- interestingness test for C-Reduce |
| """ |
| |
| from __future__ import print_function |
| from argparse import ArgumentParser, RawTextHelpFormatter |
| import os |
| import re |
| import stat |
| import sys |
| import subprocess |
| import pipes |
| import shlex |
| import tempfile |
| import shutil |
| from distutils.spawn import find_executable |
| import multiprocessing |
| |
| verbose = False |
| creduce_cmd = None |
| clang_cmd = None |
| |
| def verbose_print(*args, **kwargs): |
| if verbose: |
| print(*args, **kwargs) |
| |
| def check_file(fname): |
| fname = os.path.normpath(fname) |
| if not os.path.isfile(fname): |
| sys.exit("ERROR: %s does not exist" % (fname)) |
| return fname |
| |
| def check_cmd(cmd_name, cmd_dir, cmd_path=None): |
| """ |
| Returns absolute path to cmd_path if it is given, |
| or absolute path to cmd_dir/cmd_name. |
| """ |
| if cmd_path: |
| # Make the path absolute so the creduce test can be run from any directory. |
| cmd_path = os.path.abspath(cmd_path) |
| cmd = find_executable(cmd_path) |
| if cmd: |
| return cmd |
| sys.exit("ERROR: executable `%s` not found" % (cmd_path)) |
| |
| cmd = find_executable(cmd_name, path=cmd_dir) |
| if cmd: |
| return cmd |
| |
| if not cmd_dir: |
| cmd_dir = "$PATH" |
| sys.exit("ERROR: `%s` not found in %s" % (cmd_name, cmd_dir)) |
| |
| def quote_cmd(cmd): |
| return ' '.join(pipes.quote(arg) for arg in cmd) |
| |
| def write_to_script(text, filename): |
| with open(filename, 'w') as f: |
| f.write(text) |
| os.chmod(filename, os.stat(filename).st_mode | stat.S_IEXEC) |
| |
| class Reduce(object): |
| def __init__(self, crash_script, file_to_reduce, core_number): |
| crash_script_name, crash_script_ext = os.path.splitext(crash_script) |
| file_reduce_name, file_reduce_ext = os.path.splitext(file_to_reduce) |
| |
| self.testfile = file_reduce_name + '.test.sh' |
| self.crash_script = crash_script_name + '.reduced' + crash_script_ext |
| self.file_to_reduce = file_reduce_name + '.reduced' + file_reduce_ext |
| shutil.copy(file_to_reduce, self.file_to_reduce) |
| |
| self.clang = clang_cmd |
| self.clang_args = [] |
| self.expected_output = [] |
| self.needs_stack_trace = False |
| self.creduce_flags = ["--tidy"] |
| self.creduce_flags = ["--n", str(core_number)] |
| |
| self.read_clang_args(crash_script, file_to_reduce) |
| self.read_expected_output() |
| |
| def get_crash_cmd(self, cmd=None, args=None, filename=None): |
| if not cmd: |
| cmd = self.clang |
| if not args: |
| args = self.clang_args |
| if not filename: |
| filename = self.file_to_reduce |
| |
| return [cmd] + args + [filename] |
| |
| def read_clang_args(self, crash_script, filename): |
| print("\nReading arguments from crash script...") |
| with open(crash_script) as f: |
| # Assume clang call is the first non comment line. |
| cmd = [] |
| for line in f: |
| if not line.lstrip().startswith('#'): |
| cmd = shlex.split(line) |
| break |
| if not cmd: |
| sys.exit("Could not find command in the crash script."); |
| |
| # Remove clang and filename from the command |
| # Assume the last occurrence of the filename is the clang input file |
| del cmd[0] |
| for i in range(len(cmd)-1, -1, -1): |
| if cmd[i] == filename: |
| del cmd[i] |
| break |
| self.clang_args = cmd |
| verbose_print("Clang arguments:", quote_cmd(self.clang_args)) |
| |
| def read_expected_output(self): |
| print("\nGetting expected crash output...") |
| p = subprocess.Popen(self.get_crash_cmd(), |
| stdout=subprocess.PIPE, |
| stderr=subprocess.STDOUT) |
| crash_output, _ = p.communicate() |
| result = [] |
| |
| # Remove color codes |
| ansi_escape = r'\x1b\[[0-?]*m' |
| crash_output = re.sub(ansi_escape, '', crash_output.decode('utf-8')) |
| |
| # Look for specific error messages |
| regexes = [r"Assertion .+ failed", # Linux assert() |
| r"Assertion failed: .+,", # FreeBSD/Mac assert() |
| r"fatal error: error in backend: .+", |
| r"LLVM ERROR: .+", |
| r"UNREACHABLE executed at .+?!", |
| r"LLVM IR generation of declaration '.+'", |
| r"Generating code for declaration '.+'", |
| r"\*\*\* Bad machine code: .+ \*\*\*", |
| r"ERROR: .*Sanitizer: [^ ]+ "] |
| for msg_re in regexes: |
| match = re.search(msg_re, crash_output) |
| if match: |
| msg = match.group(0) |
| result = [msg] |
| print("Found message:", msg) |
| break |
| |
| # If no message was found, use the top five stack trace functions, |
| # ignoring some common functions |
| # Five is a somewhat arbitrary number; the goal is to get a small number |
| # of identifying functions with some leeway for common functions |
| if not result: |
| self.needs_stack_trace = True |
| stacktrace_re = r'[0-9]+\s+0[xX][0-9a-fA-F]+\s*([^(]+)\(' |
| filters = ["PrintStackTrace", "RunSignalHandlers", "CleanupOnSignal", |
| "HandleCrash", "SignalHandler", "__restore_rt", "gsignal", "abort"] |
| def skip_function(func_name): |
| return any(name in func_name for name in filters) |
| |
| matches = re.findall(stacktrace_re, crash_output) |
| result = [x for x in matches if x and not skip_function(x)][:5] |
| for msg in result: |
| print("Found stack trace function:", msg) |
| |
| if not result: |
| print("ERROR: no crash was found") |
| print("The crash output was:\n========\n%s========" % crash_output) |
| sys.exit(1) |
| |
| self.expected_output = result |
| |
| def check_expected_output(self, args=None, filename=None): |
| if not args: |
| args = self.clang_args |
| if not filename: |
| filename = self.file_to_reduce |
| |
| p = subprocess.Popen(self.get_crash_cmd(args=args, filename=filename), |
| stdout=subprocess.PIPE, |
| stderr=subprocess.STDOUT) |
| crash_output, _ = p.communicate() |
| return all(msg in crash_output.decode('utf-8') for msg in |
| self.expected_output) |
| |
| def write_interestingness_test(self): |
| print("\nCreating the interestingness test...") |
| |
| # Disable symbolization if it's not required to avoid slow symbolization. |
| disable_symbolization = '' |
| if not self.needs_stack_trace: |
| disable_symbolization = 'export LLVM_DISABLE_SYMBOLIZATION=1' |
| |
| output = """#!/bin/bash |
| %s |
| if %s >& t.log ; then |
| exit 1 |
| fi |
| """ % (disable_symbolization, quote_cmd(self.get_crash_cmd())) |
| |
| for msg in self.expected_output: |
| output += 'grep -F %s t.log || exit 1\n' % pipes.quote(msg) |
| |
| write_to_script(output, self.testfile) |
| self.check_interestingness() |
| |
| def check_interestingness(self): |
| testfile = os.path.abspath(self.testfile) |
| |
| # Check that the test considers the original file interesting |
| with open(os.devnull, 'w') as devnull: |
| returncode = subprocess.call(testfile, stdout=devnull) |
| if returncode: |
| sys.exit("The interestingness test does not pass for the original file.") |
| |
| # Check that an empty file is not interesting |
| # Instead of modifying the filename in the test file, just run the command |
| with tempfile.NamedTemporaryFile() as empty_file: |
| is_interesting = self.check_expected_output(filename=empty_file.name) |
| if is_interesting: |
| sys.exit("The interestingness test passes for an empty file.") |
| |
| def clang_preprocess(self): |
| print("\nTrying to preprocess the source file...") |
| with tempfile.NamedTemporaryFile() as tmpfile: |
| cmd_preprocess = self.get_crash_cmd() + ['-E', '-o', tmpfile.name] |
| cmd_preprocess_no_lines = cmd_preprocess + ['-P'] |
| try: |
| subprocess.check_call(cmd_preprocess_no_lines) |
| if self.check_expected_output(filename=tmpfile.name): |
| print("Successfully preprocessed with line markers removed") |
| shutil.copy(tmpfile.name, self.file_to_reduce) |
| else: |
| subprocess.check_call(cmd_preprocess) |
| if self.check_expected_output(filename=tmpfile.name): |
| print("Successfully preprocessed without removing line markers") |
| shutil.copy(tmpfile.name, self.file_to_reduce) |
| else: |
| print("No longer crashes after preprocessing -- " |
| "using original source") |
| except subprocess.CalledProcessError: |
| print("Preprocessing failed") |
| |
| @staticmethod |
| def filter_args(args, opts_equal=[], opts_startswith=[], |
| opts_one_arg_startswith=[]): |
| result = [] |
| skip_next = False |
| for arg in args: |
| if skip_next: |
| skip_next = False |
| continue |
| if any(arg == a for a in opts_equal): |
| continue |
| if any(arg.startswith(a) for a in opts_startswith): |
| continue |
| if any(arg.startswith(a) for a in opts_one_arg_startswith): |
| skip_next = True |
| continue |
| result.append(arg) |
| return result |
| |
| def try_remove_args(self, args, msg=None, extra_arg=None, **kwargs): |
| new_args = self.filter_args(args, **kwargs) |
| |
| if extra_arg: |
| if extra_arg in new_args: |
| new_args.remove(extra_arg) |
| new_args.append(extra_arg) |
| |
| if (new_args != args and |
| self.check_expected_output(args=new_args)): |
| if msg: |
| verbose_print(msg) |
| return new_args |
| return args |
| |
| def try_remove_arg_by_index(self, args, index): |
| new_args = args[:index] + args[index+1:] |
| removed_arg = args[index] |
| |
| # Heuristic for grouping arguments: |
| # remove next argument if it doesn't start with "-" |
| if index < len(new_args) and not new_args[index].startswith('-'): |
| del new_args[index] |
| removed_arg += ' ' + args[index+1] |
| |
| if self.check_expected_output(args=new_args): |
| verbose_print("Removed", removed_arg) |
| return new_args, index |
| return args, index+1 |
| |
| def simplify_clang_args(self): |
| """Simplify clang arguments before running C-Reduce to reduce the time the |
| interestingness test takes to run. |
| """ |
| print("\nSimplifying the clang command...") |
| |
| # Remove some clang arguments to speed up the interestingness test |
| new_args = self.clang_args |
| new_args = self.try_remove_args(new_args, |
| msg="Removed debug info options", |
| opts_startswith=["-gcodeview", |
| "-debug-info-kind=", |
| "-debugger-tuning="]) |
| |
| new_args = self.try_remove_args(new_args, |
| msg="Removed --show-includes", |
| opts_startswith=["--show-includes"]) |
| # Not suppressing warnings (-w) sometimes prevents the crash from occurring |
| # after preprocessing |
| new_args = self.try_remove_args(new_args, |
| msg="Replaced -W options with -w", |
| extra_arg='-w', |
| opts_startswith=["-W"]) |
| new_args = self.try_remove_args(new_args, |
| msg="Replaced optimization level with -O0", |
| extra_arg="-O0", |
| opts_startswith=["-O"]) |
| |
| # Try to remove compilation steps |
| new_args = self.try_remove_args(new_args, msg="Added -emit-llvm", |
| extra_arg="-emit-llvm") |
| new_args = self.try_remove_args(new_args, msg="Added -fsyntax-only", |
| extra_arg="-fsyntax-only") |
| |
| # Try to make implicit int an error for more sensible test output |
| new_args = self.try_remove_args(new_args, msg="Added -Werror=implicit-int", |
| opts_equal=["-w"], |
| extra_arg="-Werror=implicit-int") |
| |
| self.clang_args = new_args |
| verbose_print("Simplified command:", quote_cmd(self.get_crash_cmd())) |
| |
| def reduce_clang_args(self): |
| """Minimize the clang arguments after running C-Reduce, to get the smallest |
| command that reproduces the crash on the reduced file. |
| """ |
| print("\nReducing the clang crash command...") |
| |
| new_args = self.clang_args |
| |
| # Remove some often occurring args |
| new_args = self.try_remove_args(new_args, msg="Removed -D options", |
| opts_startswith=["-D"]) |
| new_args = self.try_remove_args(new_args, msg="Removed -D options", |
| opts_one_arg_startswith=["-D"]) |
| new_args = self.try_remove_args(new_args, msg="Removed -I options", |
| opts_startswith=["-I"]) |
| new_args = self.try_remove_args(new_args, msg="Removed -I options", |
| opts_one_arg_startswith=["-I"]) |
| new_args = self.try_remove_args(new_args, msg="Removed -W options", |
| opts_startswith=["-W"]) |
| |
| # Remove other cases that aren't covered by the heuristic |
| new_args = self.try_remove_args(new_args, msg="Removed -mllvm", |
| opts_one_arg_startswith=["-mllvm"]) |
| |
| i = 0 |
| while i < len(new_args): |
| new_args, i = self.try_remove_arg_by_index(new_args, i) |
| |
| self.clang_args = new_args |
| |
| reduced_cmd = quote_cmd(self.get_crash_cmd()) |
| write_to_script(reduced_cmd, self.crash_script) |
| print("Reduced command:", reduced_cmd) |
| |
| def run_creduce(self): |
| print("\nRunning C-Reduce...") |
| try: |
| p = subprocess.Popen([creduce_cmd] + self.creduce_flags + |
| [self.testfile, self.file_to_reduce]) |
| p.communicate() |
| except KeyboardInterrupt: |
| # Hack to kill C-Reduce because it jumps into its own pgid |
| print('\n\nctrl-c detected, killed creduce') |
| p.kill() |
| |
| def main(): |
| global verbose |
| global creduce_cmd |
| global clang_cmd |
| |
| parser = ArgumentParser(description=__doc__, |
| formatter_class=RawTextHelpFormatter) |
| parser.add_argument('crash_script', type=str, nargs=1, |
| help="Name of the script that generates the crash.") |
| parser.add_argument('file_to_reduce', type=str, nargs=1, |
| help="Name of the file to be reduced.") |
| parser.add_argument('--llvm-bin', dest='llvm_bin', type=str, |
| help="Path to the LLVM bin directory.") |
| parser.add_argument('--clang', dest='clang', type=str, |
| help="The path to the `clang` executable. " |
| "By default uses the llvm-bin directory.") |
| parser.add_argument('--creduce', dest='creduce', type=str, |
| help="The path to the `creduce` executable. " |
| "Required if `creduce` is not in PATH environment.") |
| parser.add_argument('--n', dest='core_number', type=int, |
| default=max(4, multiprocessing.cpu_count() / 2), |
| help="Number of cores to use.") |
| parser.add_argument('-v', '--verbose', action='store_true') |
| args = parser.parse_args() |
| |
| verbose = args.verbose |
| llvm_bin = os.path.abspath(args.llvm_bin) if args.llvm_bin else None |
| creduce_cmd = check_cmd('creduce', None, args.creduce) |
| clang_cmd = check_cmd('clang', llvm_bin, args.clang) |
| core_number = args.core_number |
| |
| crash_script = check_file(args.crash_script[0]) |
| file_to_reduce = check_file(args.file_to_reduce[0]) |
| |
| r = Reduce(crash_script, file_to_reduce, core_number) |
| |
| r.simplify_clang_args() |
| r.write_interestingness_test() |
| r.clang_preprocess() |
| r.run_creduce() |
| r.reduce_clang_args() |
| |
| if __name__ == '__main__': |
| main() |
