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