backtrace-check

#!/usr/bin/env python

# This script uses a regex to validate the output of our backtraces.
# The layout we assume is:
#
# <frame number> <library name> <address> <demangled name> + <offset>
#
# It currently just checks that the backtrace results in at least one correctly
# formatted entry. It does not directly validate the input since the output
# would not be robust against standard library changes.
#
# TODO: We could have the user pass in the frame number, library name, and
# demangled name. These we can always validate as true in a robust way. On the
# other hand, address and offset are more difficult to validate in a robust way
# in the face of small codegen differences, so without any further thought I
# imagine we can just check the format.
#
# 11 libswiftCore.dylib 0x000000000dce84d0l _fatalErrorMessage(StaticString,
# StaticString, StaticString, UInt, flags : UInt32) -> () + 444

from __future__ import print_function

import argparse
import re
import sys


def main():
    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description="""Checks that a stacktrace dump follows canonical
formatting.""")
    parser.add_argument(
        "-u", "--check-unavailable", action='store_true',
        help="Checks if any symbols were unavailable")
    args = parser.parse_args()

    TARGET_RE = re.compile(
        "(?P<index>\d+) +(?P<object>\S+) +(?P<address>0x[0-9a-fA-F]{16}) "
        "(?P<routine>[^+]+) [+] (?P<offset>\d+)")

    lines = sys.stdin.readlines()

    found_stack_trace_start = False
    found_stack_trace_entry = False
    for l in lines:
        l = l.rstrip("\n")

        # First see if we found the start of our stack trace start. If so, set
        # the found stack trace flag and continue.
        if l == "Current stack trace:":
            assert(not found_stack_trace_start)
            found_stack_trace_start = True
            continue

        # Otherwise, if we have not yet found the stack trace start, continue.
        # We need to find the stack trace start line.
        if not found_stack_trace_start:
            continue

        # Ok, we are in the middle of matching a stack trace entry.
        m = TARGET_RE.match(l)
        # If we fail to match, we have exited the stack trace entry region
        if m is None:
            break

        # At this point, we know that we have some sort of match.
        found_stack_trace_entry = True
        print("Stack Trace Entry:")
        print("\tIndex: '%(index)s'\n\tObject File: '%(object)s'\n\tAddress: "
              "'%(address)s'\n\tRoutine: '%(routine)s'\n\tOffset: '%(offset)s'"
              "\n" % m.groupdict())

        # Check for unavailable symbols, if that was requested.
        if args.check_unavailable:
            assert("unavailable" not in m.group("routine"))

    # Once we have processed all of the lines, make sure that we found at least
    # one stack trace entry.
    assert(found_stack_trace_entry)


if __name__ == '__main__':
    main()