view mercurial/cffi/mpatch.py @ 47055:553451522113 stable

extensions: ignore exceptions from an extension's `getversion()` method

This method is usually called when there's a stacktrace being generated, or with
`hg version -v`.  Raising another exception risks mangling the bug report info.

I hit this issue when trying to add the method to the keyring extension to
report the version of the extension and the underlying module, and ran into
demandimport issues prior to py3.8.  It seems like a wise thing to do anyway,
though unfortunately there's no convenient `ui` object around to issue a
warning.  Use 'unknown' to signal that it tried to report a version and failed,
unlike the default case of printing nothing.

Differential Revision: https://phab.mercurial-scm.org/D10540

# 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  # pytype: disable=import-error

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(b"struct mpatch_flist*[1]")
    to_pass = ffi.new(b"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(b"cannot decode chunk")
    outlen = lib.mpatch_calcsize(len(text), patch)
    if outlen < 0:
        lib.mpatch_lfree(patch)
        raise mpatchError(b"inconsistency detected")
    buf = ffi.new(b"char[]", outlen)
    if lib.mpatch_apply(buf, text, len(text), patch) < 0:
        lib.mpatch_lfree(patch)
        raise mpatchError(b"error applying patches")
    res = ffi.buffer(buf, outlen)[:]
    lib.mpatch_lfree(patch)
    return res