tests/testlib/ext-sidedata.py

py3: fix curses chunkselector fallback (when diffs are too large) on py3

Previously we showed the message using Exception.message, which is removed in
py3. Since crecordmod.fallbackerror inherits from error.Abort, we can just use
`b'%s' % exception` to print the message. This does not print the hint, but
that's fine - we don't set one. We inherit from error.Abort so that if a
codepath doesn't handle fallback specially, it exits to the terminal with a sane
message instead of an unknown exception error.

Differential Revision: https://phab.mercurial-scm.org/D7912

# ext-sidedata.py - small extension to test the sidedata logic
#
# Copyright 2019 Pierre-Yves David <[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

import hashlib
import struct

from mercurial import (
    extensions,
    localrepo,
    node,
    revlog,
    upgrade,
)

from mercurial.revlogutils import sidedata


def wrapaddrevision(
    orig, self, text, transaction, link, p1, p2, *args, **kwargs
):
    if kwargs.get('sidedata') is None:
        kwargs['sidedata'] = {}
    sd = kwargs['sidedata']
    ## let's store some arbitrary data just for testing
    # text length
    sd[sidedata.SD_TEST1] = struct.pack('>I', len(text))
    # and sha2 hashes
    sha256 = hashlib.sha256(text).digest()
    sd[sidedata.SD_TEST2] = struct.pack('>32s', sha256)
    return orig(self, text, transaction, link, p1, p2, *args, **kwargs)


def wraprevision(orig, self, nodeorrev, *args, **kwargs):
    text = orig(self, nodeorrev, *args, **kwargs)
    if getattr(self, 'sidedatanocheck', False):
        return text
    if nodeorrev != node.nullrev and nodeorrev != node.nullid:
        sd = self.sidedata(nodeorrev)
        if len(text) != struct.unpack('>I', sd[sidedata.SD_TEST1])[0]:
            raise RuntimeError('text size mismatch')
        expected = sd[sidedata.SD_TEST2]
        got = hashlib.sha256(text).digest()
        if got != expected:
            raise RuntimeError('sha256 mismatch')
    return text


def wrapgetsidedatacompanion(orig, srcrepo, dstrepo):
    sidedatacompanion = orig(srcrepo, dstrepo)
    addedreqs = dstrepo.requirements - srcrepo.requirements
    if localrepo.SIDEDATA_REQUIREMENT in addedreqs:
        assert sidedatacompanion is None  # deal with composition later

        def sidedatacompanion(revlog, rev):
            update = {}
            revlog.sidedatanocheck = True
            try:
                text = revlog.revision(rev)
            finally:
                del revlog.sidedatanocheck
            ## let's store some arbitrary data just for testing
            # text length
            update[sidedata.SD_TEST1] = struct.pack('>I', len(text))
            # and sha2 hashes
            sha256 = hashlib.sha256(text).digest()
            update[sidedata.SD_TEST2] = struct.pack('>32s', sha256)
            return False, (), update

    return sidedatacompanion


def extsetup(ui):
    extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision)
    extensions.wrapfunction(revlog.revlog, 'revision', wraprevision)
    extensions.wrapfunction(
        upgrade, 'getsidedatacompanion', wrapgetsidedatacompanion
    )