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#!/usr/bin/python
# Copyright (c) 2012 The Native Client Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Utility to decode a crash dump generated by untrusted_crash_dump.[ch]
Currently this produces a simple stack trace.
"""
import json
import optparse
import os
import posixpath
import subprocess
import sys
class CoreDecoder(object):
"""Class to process core dumps."""
def __init__(self, main_nexe, nmf_filename,
addr2line, library_paths, platform):
"""Construct and object to process core dumps.
Args:
main_nexe: nexe to resolve NaClMain references from.
nmf_filename: nmf to resovle references from.
addr2line: path to appropriate addr2line.
library_paths: list of paths to search for libraries.
platform: platform string to use in nmf files.
"""
self.main_nexe = main_nexe
self.nmf_filename = nmf_filename
if nmf_filename == '-':
self.nmf_data = {}
else:
self.nmf_data = json.load(open(nmf_filename))
self.addr2line = addr2line
self.library_paths = library_paths
self.platform = platform
def _SelectModulePath(self, filename):
"""Select which path to get a module from.
Args:
filename: filename of a module (as appears in phdrs).
Returns:
Full local path to the file.
Derived by consulting the manifest.
"""
# For some names try the main nexe.
# NaClMain is the argv[0] setup in sel_main.c
# (null) shows up in chrome.
if self.main_nexe is not None and filename in ['NaClMain', '(null)']:
return self.main_nexe
filepart = posixpath.basename(filename)
nmf_entry = self.nmf_data.get('files', {}).get(filepart, {})
nmf_url = nmf_entry.get(self.platform, {}).get('url')
# Try filename directly if not in manifest.
if nmf_url is None:
return filename
# Look for the module relative to the manifest (if any),
# then in other search paths.
paths = []
if self.nmf_filename != '-':
paths.append(os.path.dirname(self.nmf_filename))
paths.extend(self.library_paths)
for path in paths:
pfilename = os.path.join(path, nmf_url)
if os.path.exists(pfilename):
return pfilename
# If nothing else, try the path directly.
return filename
def _DecodeAddressSegment(self, segments, address):
"""Convert an address to a segment relative one, plus filename.
Args:
segments: a list of phdr segments.
address: a process wide code address.
Returns:
A tuple of filename and segment relative address.
"""
for segment in segments:
for phdr in segment['dlpi_phdr']:
start = segment['dlpi_addr'] + phdr['p_vaddr']
end = start + phdr['p_memsz']
if address >= start and address < end:
return (segment['dlpi_name'], address - segment['dlpi_addr'])
return ('(null)', address)
def _Addr2Line(self, segments, address):
"""Use addr2line to decode a code address.
Args:
segments: A list of phdr segments.
address: a code address.
Returns:
A list of dicts containing: function, filename, lineno.
"""
filename, address = self._DecodeAddressSegment(segments, address)
filename = self._SelectModulePath(filename)
if not os.path.exists(filename):
return [{
'function': 'Unknown_function',
'filename': 'unknown_file',
'lineno': -1,
}]
# Use address - 1 to get the call site instead of the line after.
address -= 1
cmd = [
self.addr2line, '-f', '--inlines', '-e', filename, '0x%08x' % address,
]
process = subprocess.Popen(cmd, stdout=subprocess.PIPE)
process_stdout, _ = process.communicate()
assert process.returncode == 0
lines = process_stdout.splitlines()
assert len(lines) % 2 == 0
results = []
for index in xrange(len(lines) / 2):
func = lines[index * 2]
afilename, lineno = lines[index * 2 + 1].split(':', 1)
results.append({
'function': func,
'filename': afilename,
'lineno': int(lineno),
})
return results
def Decode(self, text):
core = json.loads(text)
for frame in core['frames']:
frame['scopes'] = self._Addr2Line(core['segments'], frame['prog_ctr'])
return core
def LoadAndDecode(self, core_path):
"""Given a core.json file, load and embellish with decoded addresses.
Args:
core_path: source file containing a dump.
Returns:
An embelished core dump dict (decoded code addresses).
"""
core = json.load(open(core_path))
for frame in core['frames']:
frame['scopes'] = self._Addr2Line(core['segments'], frame['prog_ctr'])
return core
def StackTrace(self, info):
"""Convert a decoded core.json dump to a simple stack trace.
Args:
info: core.json info with decoded code addresses.
Returns:
A list of dicts with filename, lineno, function (deepest first).
"""
trace = []
for frame in info['frames']:
for scope in frame['scopes']:
trace.append(scope)
return trace
def PrintTrace(self, trace, out):
"""Print a trace to a file like object.
Args:
trace: A list of [filename, lineno, function] (deepest first).
out: file like object to output the trace to.
"""
for scope in trace:
out.write('%s at %s:%d\n' % (
scope['function'],
scope['filename'],
scope['lineno']))
def Main(args):
parser = optparse.OptionParser(
usage='USAGE: %prog [options] <core.json>')
parser.add_option('-m', '--main-nexe', dest='main_nexe',
help='nexe to resolve NaClMain references from')
parser.add_option('-n', '--nmf', dest='nmf_filename', default='-',
help='nmf to resolve references from')
parser.add_option('-a', '--addr2line', dest='addr2line',
help='path to appropriate addr2line')
parser.add_option('-L', '--library-path', dest='library_paths',
action='append', default=[],
help='path to search for shared libraries')
parser.add_option('-p', '--platform', dest='platform',
help='platform in a style match nmf files')
options, args = parser.parse_args(args)
if len(args) != 1:
parser.print_help()
sys.exit(1)
decoder = CoreDecoder(
main_nexe=options.main_nexe,
nmf_filename=options.nmf_filename,
addr2line=options.add2line,
library_paths=options.library_paths,
platform=options.platform)
info = decoder.LoadAndDecode(args[0])
trace = decoder.StackTrace(info)
decoder.PrintTrace(trace, sys.stdout)
if __name__ == '__main__':
Main(sys.argv[1:])
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