mercurial/cffi/mpatch.py

strip: include phases in bundle (BC)

Before this patch, unbundling a stripped changeset would make it a
draft (unless the parent was secret). This meant that one would lose
phase information when stripping and unbundling secret changesets. The
same thing was true for public changesets. While stripping public
changesets is generally rare, it's done frequently by e.g. the
narrowhg extension.

We also include the phases in the temporary bundle, just in case
stripping were to fail after that point, so the user can still restore
the repo including phase information. Before this patch, the phases
were left untouched during the bundling and unbundling of the
temporary bundle. Only at the end of the transaction would
phasecache.filterunknown() be called to remove phase roots that were
no longer valid. We now need to call that also after the first
stripping, i.e. before applying the temporary bundle. Otherwise
unbundling the temporary bundle will cause a read of the phase cache
which has stripped changesets in the cache and that fails.

Like with obsmarkers, we unconditionally include the phases in the
bundle when stripping (when using bundle2, such as when generaldelta
is enabled). The reason for doing that for strip but not for bundle is
that strip bundles are not meant to be shared outside the repo, so we
don't care as much about compatibility.

# mpatch.py - CFFI implementation of mpatch.c
#
# Copyright 2016 Maciej Fijalkowski <[e-mail]>
#
# 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

from ..pure.mpatch import *
from ..pure.mpatch import mpatchError  # silence pyflakes
from . import _mpatch

ffi = _mpatch.ffi
lib = _mpatch.lib

@ffi.def_extern()
def cffi_get_next_item(arg, pos):
    all, bins = ffi.from_handle(arg)
    container = ffi.new("struct mpatch_flist*[1]")
    to_pass = ffi.new("char[]", str(bins[pos]))
    all.append(to_pass)
    r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)
    if r < 0:
        return ffi.NULL
    return container[0]

def patches(text, bins):
    lgt = len(bins)
    all = []
    if not lgt:
        return text
    arg = (all, bins)
    patch = lib.mpatch_fold(ffi.new_handle(arg),
                            lib.cffi_get_next_item, 0, lgt)
    if not patch:
        raise mpatchError("cannot decode chunk")
    outlen = lib.mpatch_calcsize(len(text), patch)
    if outlen < 0:
        lib.mpatch_lfree(patch)
        raise mpatchError("inconsistency detected")
    buf = ffi.new("char[]", outlen)
    if lib.mpatch_apply(buf, text, len(text), patch) < 0:
        lib.mpatch_lfree(patch)
        raise mpatchError("error applying patches")
    res = ffi.buffer(buf, outlen)[:]
    lib.mpatch_lfree(patch)
    return res