tests/ls-l.py

dirs: fix out-of-bounds access in Py3

The hack for mutating Python's variable-length integers that was
ported to py3 in cb3048746dae (dirs: port PyInt code to work on Python
3, 2016-10-08) was reading from ob_digit[1] instead of ob_digit[0] for
some reason. Space for ob_digit[1] would only be allocated for
integers larger than 30 bits, so we ended up writing to unallocated
memory. Also, we would write an integer that's 2^30 times too large,
so we would never free these integers.

Found by AddressSanitizer.

Differential Revision: https://phab.mercurial-scm.org/D7597

#!/usr/bin/env python

# like ls -l, but do not print date, user, or non-common mode bit, to avoid
# using globs in tests.
from __future__ import absolute_import, print_function

import os
import stat
import sys


def modestr(st):
    mode = st.st_mode
    result = ''
    if mode & stat.S_IFDIR:
        result += 'd'
    else:
        result += '-'
    for owner in ['USR', 'GRP', 'OTH']:
        for action in ['R', 'W', 'X']:
            if mode & getattr(stat, 'S_I%s%s' % (action, owner)):
                result += action.lower()
            else:
                result += '-'
    return result


def sizestr(st):
    if st.st_mode & stat.S_IFREG:
        return '%7d' % st.st_size
    else:
        # do not show size for non regular files
        return ' ' * 7


os.chdir((sys.argv[1:] + ['.'])[0])

for name in sorted(os.listdir('.')):
    st = os.stat(name)
    print('%s %s %s' % (modestr(st), sizestr(st), name))