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# Copyright 2017 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import logging
import os
import re
import subprocess
import threading
_CHROME_SRC = os.path.join(os.path.dirname(__file__), os.pardir, os.pardir)
_LLVM_SYMBOLIZER_PATH = os.path.join(
_CHROME_SRC, 'third_party', 'llvm-build', 'Release+Asserts', 'bin',
'llvm-symbolizer')
_BINARY = re.compile(r'0b[0,1]+')
_HEX = re.compile(r'0x[0-9,a-e]+')
_OCTAL = re.compile(r'0[0-7]+')
_UNKNOWN = '<UNKNOWN>'
def _CheckValidAddr(addr):
"""
Check whether the addr is valid input to llvm symbolizer.
Valid addr has to be octal, binary, or hex number.
Args:
addr: addr to be entered to llvm symbolizer.
Returns:
whether the addr is valid input to llvm symbolizer.
"""
return _HEX.match(addr) or _OCTAL.match(addr) or _BINARY.match(addr)
class LLVMSymbolizer(object):
def __init__(self):
"""Create a LLVMSymbolizer instance that interacts with the llvm symbolizer.
The purpose of the LLVMSymbolizer is to get function names and line
numbers of an address from the symbols library.
"""
self._llvm_symbolizer_subprocess = None
# Allow only one thread to call GetSymbolInformation at a time.
self._lock = threading.Lock()
def Start(self):
"""Start the llvm symbolizer subprocess.
Create a subprocess of the llvm symbolizer executable, which will be used
to retrieve function names etc.
"""
if os.path.isfile(_LLVM_SYMBOLIZER_PATH):
self._llvm_symbolizer_subprocess = subprocess.Popen(
[_LLVM_SYMBOLIZER_PATH], stdout=subprocess.PIPE, stdin=subprocess.PIPE)
else:
logging.error('Cannot find llvm_symbolizer here: %s.' %
_LLVM_SYMBOLIZER_PATH)
self._llvm_symbolizer_subprocess = None
def Close(self):
"""Close the llvm symbolizer subprocess.
Close the subprocess by closing stdin, stdout and killing the subprocess.
"""
with self._lock:
if self._llvm_symbolizer_subprocess:
self._llvm_symbolizer_subprocess.kill()
self._llvm_symbolizer_subprocess = None
def __enter__(self):
"""Start the llvm symbolizer subprocess."""
self.Start()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
"""Close the llvm symbolizer subprocess."""
self.Close()
def GetSymbolInformation(self, lib, addr):
"""Return the corresponding function names and line numbers.
Args:
lib: library to search for info.
addr: address to look for info.
Returns:
A list of (function name, line numbers) tuple.
"""
if (self._llvm_symbolizer_subprocess is None or not lib
or not _CheckValidAddr(addr) or not os.path.isfile(lib)):
return [(_UNKNOWN, lib)]
with self._lock:
self._llvm_symbolizer_subprocess.stdin.write('%s %s\n' % (lib, addr))
self._llvm_symbolizer_subprocess.stdin.flush()
result = []
# Read till see new line, which is a symbol of end of output.
# One line of function name is always followed by one line of line number.
while True:
line = self._llvm_symbolizer_subprocess.stdout.readline()
if line != '\n':
line_numbers = self._llvm_symbolizer_subprocess.stdout.readline()
result.append(
(line[:-1],
line_numbers[:-1]))
else:
return result
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