view mercurial/pure/bdiff.py @ 30884:a68510b69f41

chg: verify XDG_RUNTIME_DIR

According to the specification [1], $XDG_RUNTIME_DIR should be ignored
unless:

  The directory MUST be owned by the user, and he MUST be the only one
  having read and write access to it. Its Unix access mode MUST be 0700.

This patch adds a check and ignores it if it does not meet part of the
criteria.

[1]: https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

# bdiff.py - Python implementation of bdiff.c
#
# Copyright 2009 Matt Mackall <[e-mail]> and others
#
# 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 array
import difflib
import re
import struct

from . import policy
policynocffi = policy.policynocffi
modulepolicy = policy.policy

def splitnewlines(text):
    '''like str.splitlines, but only split on newlines.'''
    lines = [l + '\n' for l in text.split('\n')]
    if lines:
        if lines[-1] == '\n':
            lines.pop()
        else:
            lines[-1] = lines[-1][:-1]
    return lines

def _normalizeblocks(a, b, blocks):
    prev = None
    r = []
    for curr in blocks:
        if prev is None:
            prev = curr
            continue
        shift = 0

        a1, b1, l1 = prev
        a1end = a1 + l1
        b1end = b1 + l1

        a2, b2, l2 = curr
        a2end = a2 + l2
        b2end = b2 + l2
        if a1end == a2:
            while (a1end + shift < a2end and
                   a[a1end + shift] == b[b1end + shift]):
                shift += 1
        elif b1end == b2:
            while (b1end + shift < b2end and
                   a[a1end + shift] == b[b1end + shift]):
                shift += 1
        r.append((a1, b1, l1 + shift))
        prev = a2 + shift, b2 + shift, l2 - shift
    r.append(prev)
    return r

def _tostring(c):
    if type(c) is array.array:
        # this copy overhead isn't ideal
        return c.tostring()
    return str(c)

def bdiff(a, b):
    a = _tostring(a).splitlines(True)
    b = _tostring(b).splitlines(True)

    if not a:
        s = "".join(b)
        return s and (struct.pack(">lll", 0, 0, len(s)) + s)

    bin = []
    p = [0]
    for i in a: p.append(p[-1] + len(i))

    d = difflib.SequenceMatcher(None, a, b).get_matching_blocks()
    d = _normalizeblocks(a, b, d)
    la = 0
    lb = 0
    for am, bm, size in d:
        s = "".join(b[lb:bm])
        if am > la or s:
            bin.append(struct.pack(">lll", p[la], p[am], len(s)) + s)
        la = am + size
        lb = bm + size

    return "".join(bin)

def blocks(a, b):
    an = splitnewlines(a)
    bn = splitnewlines(b)
    d = difflib.SequenceMatcher(None, an, bn).get_matching_blocks()
    d = _normalizeblocks(an, bn, d)
    return [(i, i + n, j, j + n) for (i, j, n) in d]

def fixws(text, allws):
    if allws:
        text = re.sub('[ \t\r]+', '', text)
    else:
        text = re.sub('[ \t\r]+', ' ', text)
        text = text.replace(' \n', '\n')
    return text

if modulepolicy not in policynocffi:
    try:
        from _bdiff_cffi import ffi, lib
    except ImportError:
        if modulepolicy == 'cffi': # strict cffi import
            raise
    else:
        def blocks(sa, sb):
            a = ffi.new("struct bdiff_line**")
            b = ffi.new("struct bdiff_line**")
            ac = ffi.new("char[]", str(sa))
            bc = ffi.new("char[]", str(sb))
            l = ffi.new("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("struct bdiff_line**")
            b = ffi.new("struct bdiff_line**")
            ac = ffi.new("char[]", str(sa))
            bc = ffi.new("char[]", str(sb))
            l = ffi.new("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(">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 "".join(rl)