#!/usr/bin/env python3
# symbolicate-linux-fatal - Symbolicate Linux stack traces -*- python -*-
#
# This source file is part of the Swift.org open source project
#
# Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
# Licensed under Apache License v2.0 with Runtime Library Exception
#
# See https://swift.org/LICENSE.txt for license information
# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
#
# ----------------------------------------------------------------------------
#
# Symbolicates fatalError stack traces on Linux. Takes the main binary
# and a log file containing a stack trace. Non-stacktrace lines are output
# unmodified. Stack trace elements are analyzed using reconstructed debug
# target matching the original process in where shared libs where mapped.
#
# TODOs:
# * verbose output
# * search symbols by name for the not <unavailable> ones
#
# ----------------------------------------------------------------------------
import argparse
import datetime
import os
import subprocess
import sys
try:
import lldb
except ImportError:
from distutils import spawn
swift_exec = spawn.find_executable('swift')
if swift_exec is not None:
site_packages = os.path.join(os.path.dirname(swift_exec),
'../lib/python2.7/site-packages/')
sys.path.append(site_packages)
import lldb
lldb_target = None
known_memmap = {}
def print_with_flush(buff):
print(buff)
sys.stdout.flush()
def process_ldd(lddoutput):
dyn_libs = {}
for line in lddoutput.splitlines():
ldd_tokens = line.split()
if len(ldd_tokens) >= 2:
lib = ldd_tokens[-2]
dyn_libs[ldd_tokens[0]] = lib
real_name = os.path.basename(os.path.realpath(lib))
dyn_libs[real_name] = lib
return dyn_libs
def setup_lldb_target(binary, memmap):
global lldb_target
if not lldb_target:
lldb_debugger = lldb.SBDebugger.Create()
lldb_target = lldb_debugger.CreateTarget(binary)
module = lldb_target.GetModuleAtIndex(0)
for dynlib_path in memmap:
module = lldb_target.AddModule(
dynlib_path, lldb.LLDB_ARCH_DEFAULT, None, None)
text_section = module.FindSection(".text")
slide = text_section.GetFileAddress() - text_section.GetFileOffset()
lldb_target.SetModuleLoadAddress(module, memmap[dynlib_path] - slide)
def check_base_address(dynlib_path, dynlib_baseaddr, memmap):
global known_memmap
if dynlib_path in memmap or dynlib_path in known_memmap:
if dynlib_path in memmap:
existing_baseaddr = memmap[dynlib_path]
else:
existing_baseaddr = known_memmap[dynlib_path]
if existing_baseaddr != dynlib_baseaddr:
error_msg = "Mismatched base address for: {0:s}, " \
"had: {1:x}, now got {2:x}"
error_msg = error_msg.format(
dynlib_path, existing_baseaddr, dynlib_baseaddr)
raise Exception(error_msg)
def symbolicate_one(frame_addr, frame_idx, dynlib_fname):
global lldb_target
so_addr = lldb_target.ResolveLoadAddress(frame_addr - 1)
sym_ctx = so_addr.GetSymbolContext(lldb.eSymbolContextEverything)
frame_fragment = "{0: <4d} {1:20s} 0x{2:016x}".format(
frame_idx, dynlib_fname, frame_addr)
symbol = sym_ctx.GetSymbol()
if not symbol.IsValid():
raise Exception("symbol isn't valid")
symbol_base = symbol.GetStartAddress().GetLoadAddress(lldb_target)
symbol_fragment = "{0:s} + {1:d}".format(
symbol.GetName(), frame_addr - symbol_base)
line_entry = sym_ctx.GetLineEntry()
if line_entry.IsValid():
line_fragment = "at {0:s}:{1:d}".format(
line_entry.GetFileSpec().GetFilename(), line_entry.GetLine())
else:
line_fragment = ""
return "{0:s} {1:s} {2:s}".format(
frame_fragment, symbol_fragment, line_fragment)
def get_processed_stack(binary, dyn_libs, stack):
global lldb_target
global known_memmap
processed_stack = []
if len(stack) == 0:
return processed_stack
memmap = {}
full_stack = []
for line in stack:
stack_tokens = line.split()
dynlib_fname = stack_tokens[1]
if dynlib_fname in dyn_libs:
dynlib_path = dyn_libs[dynlib_fname]
elif dynlib_fname in binary:
dynlib_path = binary
else:
dynlib_path = None
try:
framePC = int(stack_tokens[2], 16)
symbol_offset = int(stack_tokens[-1], 10)
except Exception:
full_stack.append({"line": line, "framePC": 0, "dynlib_fname": ""})
continue
if "<unavailable>" in stack_tokens[3]:
dynlib_baseaddr = framePC - symbol_offset
check_base_address(dynlib_path, dynlib_baseaddr, memmap)
known_memmap[dynlib_path] = dynlib_baseaddr
memmap[dynlib_path] = dynlib_baseaddr
else:
framePC = framePC + symbol_offset
full_stack.append(
{"line": line, "framePC": framePC, "dynlib_fname": dynlib_fname})
setup_lldb_target(binary, memmap)
for frame_idx, frame in enumerate(full_stack):
frame_addr = frame["framePC"]
dynlib_fname = frame["dynlib_fname"]
try:
sym_line = symbolicate_one(frame_addr, frame_idx, dynlib_fname)
processed_stack.append(sym_line)
except Exception:
processed_stack.append(frame["line"].rstrip())
return processed_stack
def is_fatal_error(line):
return line.startswith("Fatal error:")
def is_stack_trace_header(line):
return line.startswith("Current stack trace:")
def should_print_previous_line(current_line, previous_line):
return is_fatal_error(previous_line) and \
not is_stack_trace_header(current_line)
def should_print_current_line(current_line, previous_line):
return (not is_fatal_error(current_line) and
not is_stack_trace_header(current_line)) or \
(is_stack_trace_header(current_line) and
not is_fatal_error(previous_line))
def fatal_error_with_stack_trace_found(current_line, previous_line):
return is_stack_trace_header(current_line) and \
is_fatal_error(previous_line)
def print_stack(fatal_error_header,
fatal_error_stack_trace_header,
fatal_log_format,
processed_stack):
if not fatal_error_header:
for line in processed_stack:
print_with_flush(line)
else:
# fatal error with a stack trace
stack_str = fatal_error_header + fatal_error_stack_trace_header + \
'\n'.join(processed_stack)
formatted_output = fatal_log_format
if "%t" in formatted_output:
current_time = datetime.datetime.now()
time_in_iso_format = \
current_time.strftime('%Y-%m-%dT%H:%M:%S,%f%z')
formatted_output = \
formatted_output.replace("%t", time_in_iso_format)
if "%m" in formatted_output:
formatted_output = formatted_output.replace("%m", stack_str)
print_with_flush(formatted_output)
def main():
parser = argparse.ArgumentParser(
formatter_class=argparse.RawDescriptionHelpFormatter,
description="""Symbolicates stack traces in Linux log files.""")
parser.add_argument(
"binary", help="Executable which produced the log file")
parser.add_argument(
"log", nargs='?', type=argparse.FileType("rU"), default="-",
help="Log file for symbolication. Defaults to stdin.")
parser.add_argument(
"--fatal-log-format", default="%m",
help="Format for logging fatal errors. Variable %%t will be "
"replaced with current time in ISO 8601 format, variable "
"%%m will be replaced with the error message with a full "
"stack trace.")
args = parser.parse_args()
binary = args.binary
fatal_log_format = args.fatal_log_format
lddoutput = subprocess.check_output(
['ldd', binary], stderr=subprocess.STDOUT)
dyn_libs = process_ldd(lddoutput)
instack = False
previous_line = ""
stackidx = 0
stack = []
fatal_error_header = ""
fatal_error_stack_trace_header = ""
while True:
current_line = args.log.readline()
if not current_line:
break
if instack and current_line.startswith(str(stackidx)):
stack.append(current_line)
stackidx = stackidx + 1
else:
processed_stack = get_processed_stack(binary, dyn_libs, stack)
print_stack(fatal_error_header,
fatal_error_stack_trace_header,
fatal_log_format,
processed_stack)
instack = False
stackidx = 0
stack = []
fatal_error_header = ""
fatal_error_stack_trace_header = ""
if is_stack_trace_header(current_line):
instack = True
if should_print_previous_line(current_line, previous_line):
print_with_flush(previous_line.rstrip())
if should_print_current_line(current_line, previous_line):
print_with_flush(current_line.rstrip())
if fatal_error_with_stack_trace_found(current_line, previous_line):
fatal_error_header = previous_line
fatal_error_stack_trace_header = current_line
previous_line = current_line
if is_fatal_error(previous_line):
print_with_flush(previous_line.rstrip())
processed_stack = get_processed_stack(binary, dyn_libs, stack)
print_stack(fatal_error_header,
fatal_error_stack_trace_header,
fatal_log_format,
processed_stack)
if __name__ == '__main__':
main()