Add library offsets to otherwise useless WebKit crash tracebacks (requires saving /proc/{pid}/maps somewhere before the crash)

traceback-add-offsets.py

import os
import re
from collections import namedtuple

path_maps = os.path.expanduser("~/tmp/rpi-crash-maps")
path_stack = os.path.expanduser("~/tmp/rpi-crash-stack")

MapsLine = namedtuple("MapsLine", ["start", "end", "file"])


def parse_maps_line(line):
    fields = re.split("\s+", line.strip())
    start, end = [int(pointer, 16) for pointer in fields[0].split("-")]
    file = fields[5] if len(fields) >= 6 else ""
    return MapsLine(start, end, file)


memory_maps = [
    parse_maps_line(line)
    for line in open(path_maps, "r").readlines()
    if line.strip() != "" and " r-xp " in line
]


def find_map_containing(pointer):
    assert isinstance(pointer, int)
    matches = [
        map
        for map in memory_maps
        if map.start < pointer < map.end
    ]
    assert len(matches) == 1, "Could not find a match for %x" % pointer
    return matches[0]


def parse_stack_line(line):
    match = re.match(r"\d+\s+(0x[a-f0-9]+).*", line)
    assert match, "Could not parse: %s" % repr(line)
    return int(match.groups()[0], 16)


stack_lines = [
    parse_stack_line(line)
    for line in open(path_stack, "r").readlines()
    if line.strip() != ""
]


for i, pointer in enumerate(stack_lines, 1):
    memory_map = find_map_containing(pointer)
    print("    #%d 0x%x " % (i, pointer), end="")
    if memory_map:
        print("(%s+0x%x)" % (memory_map.file, pointer - memory_map.start))
    else:
        print("[GARBAGE]")