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dirs: resolve fuzzer OOM situation by disallowing deep directory hierarchies...
dirs: resolve fuzzer OOM situation by disallowing deep directory hierarchies It seems like 2048 directories ought to be enough for any reasonable use of Mercurial? A previous version of this patch scanned for slashes before any allocations occurred. That approach is slower than this in the happy path, but much faster than this in the case that too many slashes are encountered. We may want to revisit it in the future using memchr() so it'll be well-optimized by the libc we're using. .. bc: Mercurial will now defend against OOMs by refusing to operate on paths with 2048 or more components. This means that _extremely_ deep path hierarchies will be rejected, but we anticipate nobody is using hierarchies this deep. Differential Revision: https://phab.mercurial-scm.org/D7411

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bdiff.py
84 lines | 2.3 KiB | text/x-python | PythonLexer
# bdiff.py - CFFI implementation of bdiff.c
#
# Copyright 2016 Maciej Fijalkowski <fijall@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import struct
from ..pure.bdiff import *
from . import _bdiff
ffi = _bdiff.ffi
lib = _bdiff.lib
def blocks(sa, sb):
a = ffi.new(b"struct bdiff_line**")
b = ffi.new(b"struct bdiff_line**")
ac = ffi.new(b"char[]", str(sa))
bc = ffi.new(b"char[]", str(sb))
l = ffi.new(b"struct bdiff_hunk*")
try:
an = lib.bdiff_splitlines(ac, len(sa), a)
bn = lib.bdiff_splitlines(bc, len(sb), b)
if not a[0] or not b[0]:
raise MemoryError
count = lib.bdiff_diff(a[0], an, b[0], bn, l)
if count < 0:
raise MemoryError
rl = [None] * count
h = l.next
i = 0
while h:
rl[i] = (h.a1, h.a2, h.b1, h.b2)
h = h.next
i += 1
finally:
lib.free(a[0])
lib.free(b[0])
lib.bdiff_freehunks(l.next)
return rl
def bdiff(sa, sb):
a = ffi.new(b"struct bdiff_line**")
b = ffi.new(b"struct bdiff_line**")
ac = ffi.new(b"char[]", str(sa))
bc = ffi.new(b"char[]", str(sb))
l = ffi.new(b"struct bdiff_hunk*")
try:
an = lib.bdiff_splitlines(ac, len(sa), a)
bn = lib.bdiff_splitlines(bc, len(sb), b)
if not a[0] or not b[0]:
raise MemoryError
count = lib.bdiff_diff(a[0], an, b[0], bn, l)
if count < 0:
raise MemoryError
rl = []
h = l.next
la = lb = 0
while h:
if h.a1 != la or h.b1 != lb:
lgt = (b[0] + h.b1).l - (b[0] + lb).l
rl.append(
struct.pack(
b">lll",
(a[0] + la).l - a[0].l,
(a[0] + h.a1).l - a[0].l,
lgt,
)
)
rl.append(str(ffi.buffer((b[0] + lb).l, lgt)))
la = h.a2
lb = h.b2
h = h.next
finally:
lib.free(a[0])
lib.free(b[0])
lib.bdiff_freehunks(l.next)
return b"".join(rl)