vcsserver/hg.py

# RhodeCode VCSServer provides access to different vcs backends via network.
# Copyright (C) 2014-2020 RhodeCode GmbH
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA

import io
import logging
import stat
import urllib.request, urllib.parse, urllib.error
import urllib.request, urllib.error, urllib.parse
import traceback

from hgext import largefiles, rebase, purge
from hgext.strip import strip as hgext_strip
from mercurial import commands
from mercurial import unionrepo
from mercurial import verify
from mercurial import repair

import vcsserver
from vcsserver import exceptions
from vcsserver.base import RepoFactory, obfuscate_qs, raise_from_original
from vcsserver.hgcompat import (
    archival, bin, clone, config as hgconfig, diffopts, hex, get_ctx,
    hg_url as url_parser, httpbasicauthhandler, httpdigestauthhandler,
    makepeer, instance, match, memctx, exchange, memfilectx, nullrev, hg_merge,
    patch, peer, revrange, ui, hg_tag, Abort, LookupError, RepoError,
    RepoLookupError, InterventionRequired, RequirementError)
from vcsserver.vcs_base import RemoteBase

log = logging.getLogger(__name__)


def make_ui_from_config(repo_config):

    class LoggingUI(ui.ui):
        def status(self, *msg, **opts):
            log.info(' '.join(msg).rstrip('\n'))
            super(LoggingUI, self).status(*msg, **opts)

        def warn(self, *msg, **opts):
            log.warn(' '.join(msg).rstrip('\n'))
            super(LoggingUI, self).warn(*msg, **opts)

        def error(self, *msg, **opts):
            log.error(' '.join(msg).rstrip('\n'))
            super(LoggingUI, self).error(*msg, **opts)

        def note(self, *msg, **opts):
            log.info(' '.join(msg).rstrip('\n'))
            super(LoggingUI, self).note(*msg, **opts)

        def debug(self, *msg, **opts):
            log.debug(' '.join(msg).rstrip('\n'))
            super(LoggingUI, self).debug(*msg, **opts)

    baseui = LoggingUI()

    # clean the baseui object
    baseui._ocfg = hgconfig.config()
    baseui._ucfg = hgconfig.config()
    baseui._tcfg = hgconfig.config()

    for section, option, value in repo_config:
        baseui.setconfig(section, option, value)

    # make our hgweb quiet so it doesn't print output
    baseui.setconfig('ui', 'quiet', 'true')

    baseui.setconfig('ui', 'paginate', 'never')
    # for better Error reporting of Mercurial
    baseui.setconfig('ui', 'message-output', 'stderr')

    # force mercurial to only use 1 thread, otherwise it may try to set a
    # signal in a non-main thread, thus generating a ValueError.
    baseui.setconfig('worker', 'numcpus', 1)

    # If there is no config for the largefiles extension, we explicitly disable
    # it here. This overrides settings from repositories hgrc file. Recent
    # mercurial versions enable largefiles in hgrc on clone from largefile
    # repo.
    if not baseui.hasconfig('extensions', 'largefiles'):
        log.debug('Explicitly disable largefiles extension for repo.')
        baseui.setconfig('extensions', 'largefiles', '!')

    return baseui


def reraise_safe_exceptions(func):
    """Decorator for converting mercurial exceptions to something neutral."""

    def wrapper(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except (Abort, InterventionRequired) as e:
            raise_from_original(exceptions.AbortException(e))
        except RepoLookupError as e:
            raise_from_original(exceptions.LookupException(e))
        except RequirementError as e:
            raise_from_original(exceptions.RequirementException(e))
        except RepoError as e:
            raise_from_original(exceptions.VcsException(e))
        except LookupError as e:
            raise_from_original(exceptions.LookupException(e))
        except Exception as e:
            if not hasattr(e, '_vcs_kind'):
                log.exception("Unhandled exception in hg remote call")
                raise_from_original(exceptions.UnhandledException(e))

            raise
    return wrapper


class MercurialFactory(RepoFactory):
    repo_type = 'hg'

    def _create_config(self, config, hooks=True):
        if not hooks:
            hooks_to_clean = frozenset((
                'changegroup.repo_size', 'preoutgoing.pre_pull',
                'outgoing.pull_logger', 'prechangegroup.pre_push'))
            new_config = []
            for section, option, value in config:
                if section == 'hooks' and option in hooks_to_clean:
                    continue
                new_config.append((section, option, value))
            config = new_config

        baseui = make_ui_from_config(config)
        return baseui

    def _create_repo(self, wire, create):
        baseui = self._create_config(wire["config"])
        return instance(baseui, wire["path"], create)

    def repo(self, wire, create=False):
        """
        Get a repository instance for the given path.
        """
        return self._create_repo(wire, create)


def patch_ui_message_output(baseui):
    baseui.setconfig('ui', 'quiet', 'false')
    output = io.BytesIO()

    def write(data, **unused_kwargs):
        output.write(data)

    baseui.status = write
    baseui.write = write
    baseui.warn = write
    baseui.debug = write

    return baseui, output


class HgRemote(RemoteBase):

    def __init__(self, factory):
        self._factory = factory
        self._bulk_methods = {
            "affected_files": self.ctx_files,
            "author": self.ctx_user,
            "branch": self.ctx_branch,
            "children": self.ctx_children,
            "date": self.ctx_date,
            "message": self.ctx_description,
            "parents": self.ctx_parents,
            "status": self.ctx_status,
            "obsolete": self.ctx_obsolete,
            "phase": self.ctx_phase,
            "hidden": self.ctx_hidden,
            "_file_paths": self.ctx_list,
        }

    def _get_ctx(self, repo, ref):
        return get_ctx(repo, ref)

    @reraise_safe_exceptions
    def discover_hg_version(self):
        from mercurial import util
        return util.version()

    @reraise_safe_exceptions
    def is_empty(self, wire):
        repo = self._factory.repo(wire)

        try:
            return len(repo) == 0
        except Exception:
            log.exception("failed to read object_store")
            return False

    @reraise_safe_exceptions
    def archive_repo(self, archive_path, mtime, file_info, kind):
        if kind == "tgz":
            archiver = archival.tarit(archive_path, mtime, "gz")
        elif kind == "tbz2":
            archiver = archival.tarit(archive_path, mtime, "bz2")
        elif kind == 'zip':
            archiver = archival.zipit(archive_path, mtime)
        else:
            raise exceptions.ArchiveException()(
                'Remote does not support: "%s".' % kind)

        for f_path, f_mode, f_is_link, f_content in file_info:
            archiver.addfile(f_path, f_mode, f_is_link, f_content)
        archiver.done()

    @reraise_safe_exceptions
    def bookmarks(self, wire):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _bookmarks(_context_uid, _repo_id):
            repo = self._factory.repo(wire)
            return dict(repo._bookmarks)

        return _bookmarks(context_uid, repo_id)

    @reraise_safe_exceptions
    def branches(self, wire, normal, closed):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _branches(_context_uid, _repo_id, _normal, _closed):
            repo = self._factory.repo(wire)
            iter_branches = repo.branchmap().iterbranches()
            bt = {}
            for branch_name, _heads, tip, is_closed in iter_branches:
                if normal and not is_closed:
                    bt[branch_name] = tip
                if closed and is_closed:
                    bt[branch_name] = tip

            return bt

        return _branches(context_uid, repo_id, normal, closed)

    @reraise_safe_exceptions
    def bulk_request(self, wire, commit_id, pre_load):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _bulk_request(_repo_id, _commit_id, _pre_load):
            result = {}
            for attr in pre_load:
                try:
                    method = self._bulk_methods[attr]
                    result[attr] = method(wire, commit_id)
                except KeyError as e:
                    raise exceptions.VcsException(e)(
                        'Unknown bulk attribute: "%s"' % attr)
            return result

        return _bulk_request(repo_id, commit_id, sorted(pre_load))

    @reraise_safe_exceptions
    def ctx_branch(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_branch(_repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return ctx.branch()
        return _ctx_branch(repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_date(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_date(_repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return ctx.date()
        return _ctx_date(repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_description(self, wire, revision):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        return ctx.description()

    @reraise_safe_exceptions
    def ctx_files(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_files(_repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return ctx.files()

        return _ctx_files(repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_list(self, path, revision):
        repo = self._factory.repo(path)
        ctx = self._get_ctx(repo, revision)
        return list(ctx)

    @reraise_safe_exceptions
    def ctx_parents(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_parents(_repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return [parent.hex() for parent in ctx.parents()
                    if not (parent.hidden() or parent.obsolete())]

        return _ctx_parents(repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_children(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_children(_repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return [child.hex() for child in ctx.children()
                    if not (child.hidden() or child.obsolete())]

        return _ctx_children(repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_phase(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_phase(_context_uid, _repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            # public=0, draft=1, secret=3
            return ctx.phase()
        return _ctx_phase(context_uid, repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_obsolete(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_obsolete(_context_uid, _repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return ctx.obsolete()
        return _ctx_obsolete(context_uid, repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_hidden(self, wire, commit_id):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _ctx_hidden(_context_uid, _repo_id, _commit_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            return ctx.hidden()
        return _ctx_hidden(context_uid, repo_id, commit_id)

    @reraise_safe_exceptions
    def ctx_substate(self, wire, revision):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        return ctx.substate

    @reraise_safe_exceptions
    def ctx_status(self, wire, revision):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        status = repo[ctx.p1().node()].status(other=ctx.node())
        # object of status (odd, custom named tuple in mercurial) is not
        # correctly serializable, we make it a list, as the underling
        # API expects this to be a list
        return list(status)

    @reraise_safe_exceptions
    def ctx_user(self, wire, revision):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        return ctx.user()

    @reraise_safe_exceptions
    def check_url(self, url, config):
        _proto = None
        if '+' in url[:url.find('://')]:
            _proto = url[0:url.find('+')]
            url = url[url.find('+') + 1:]
        handlers = []
        url_obj = url_parser(url)
        test_uri, authinfo = url_obj.authinfo()
        url_obj.passwd = '*****' if url_obj.passwd else url_obj.passwd
        url_obj.query = obfuscate_qs(url_obj.query)

        cleaned_uri = str(url_obj)
        log.info("Checking URL for remote cloning/import: %s", cleaned_uri)

        if authinfo:
            # create a password manager
            passmgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()
            passmgr.add_password(*authinfo)

            handlers.extend((httpbasicauthhandler(passmgr),
                             httpdigestauthhandler(passmgr)))

        o = urllib.request.build_opener(*handlers)
        o.addheaders = [('Content-Type', 'application/mercurial-0.1'),
                        ('Accept', 'application/mercurial-0.1')]

        q = {"cmd": 'between'}
        q.update({'pairs': "%s-%s" % ('0' * 40, '0' * 40)})
        qs = '?%s' % urllib.parse.urlencode(q)
        cu = "%s%s" % (test_uri, qs)
        req = urllib.request.Request(cu, None, {})

        try:
            log.debug("Trying to open URL %s", cleaned_uri)
            resp = o.open(req)
            if resp.code != 200:
                raise exceptions.URLError()('Return Code is not 200')
        except Exception as e:
            log.warning("URL cannot be opened: %s", cleaned_uri, exc_info=True)
            # means it cannot be cloned
            raise exceptions.URLError(e)("[%s] org_exc: %s" % (cleaned_uri, e))

        # now check if it's a proper hg repo, but don't do it for svn
        try:
            if _proto == 'svn':
                pass
            else:
                # check for pure hg repos
                log.debug(
                    "Verifying if URL is a Mercurial repository: %s",
                    cleaned_uri)
                ui = make_ui_from_config(config)
                peer_checker = makepeer(ui, url)
                peer_checker.lookup('tip')
        except Exception as e:
            log.warning("URL is not a valid Mercurial repository: %s",
                        cleaned_uri)
            raise exceptions.URLError(e)(
                "url [%s] does not look like an hg repo org_exc: %s"
                % (cleaned_uri, e))

        log.info("URL is a valid Mercurial repository: %s", cleaned_uri)
        return True

    @reraise_safe_exceptions
    def diff(self, wire, commit_id_1, commit_id_2, file_filter, opt_git, opt_ignorews, context):
        repo = self._factory.repo(wire)

        if file_filter:
            match_filter = match(file_filter[0], '', [file_filter[1]])
        else:
            match_filter = file_filter
        opts = diffopts(git=opt_git, ignorews=opt_ignorews, context=context, showfunc=1)

        try:
            return "".join(patch.diff(
                repo, node1=commit_id_1, node2=commit_id_2, match=match_filter, opts=opts))
        except RepoLookupError as e:
            raise exceptions.LookupException(e)()

    @reraise_safe_exceptions
    def node_history(self, wire, revision, path, limit):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _node_history(_context_uid, _repo_id, _revision, _path, _limit):
            repo = self._factory.repo(wire)

            ctx = self._get_ctx(repo, revision)
            fctx = ctx.filectx(path)

            def history_iter():
                limit_rev = fctx.rev()
                for obj in reversed(list(fctx.filelog())):
                    obj = fctx.filectx(obj)
                    ctx = obj.changectx()
                    if ctx.hidden() or ctx.obsolete():
                        continue

                    if limit_rev >= obj.rev():
                        yield obj

            history = []
            for cnt, obj in enumerate(history_iter()):
                if limit and cnt >= limit:
                    break
                history.append(hex(obj.node()))

            return [x for x in history]
        return _node_history(context_uid, repo_id, revision, path, limit)

    @reraise_safe_exceptions
    def node_history_untill(self, wire, revision, path, limit):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _node_history_until(_context_uid, _repo_id):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, revision)
            fctx = ctx.filectx(path)

            file_log = list(fctx.filelog())
            if limit:
                # Limit to the last n items
                file_log = file_log[-limit:]

            return [hex(fctx.filectx(cs).node()) for cs in reversed(file_log)]
        return _node_history_until(context_uid, repo_id, revision, path, limit)

    @reraise_safe_exceptions
    def fctx_annotate(self, wire, revision, path):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        fctx = ctx.filectx(path)

        result = []
        for i, annotate_obj in enumerate(fctx.annotate(), 1):
            ln_no = i
            sha = hex(annotate_obj.fctx.node())
            content = annotate_obj.text
            result.append((ln_no, sha, content))
        return result

    @reraise_safe_exceptions
    def fctx_node_data(self, wire, revision, path):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        fctx = ctx.filectx(path)
        return fctx.data()

    @reraise_safe_exceptions
    def fctx_flags(self, wire, commit_id, path):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _fctx_flags(_repo_id, _commit_id, _path):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            fctx = ctx.filectx(path)
            return fctx.flags()

        return _fctx_flags(repo_id, commit_id, path)

    @reraise_safe_exceptions
    def fctx_size(self, wire, commit_id, path):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _fctx_size(_repo_id, _revision, _path):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, commit_id)
            fctx = ctx.filectx(path)
            return fctx.size()
        return _fctx_size(repo_id, commit_id, path)

    @reraise_safe_exceptions
    def get_all_commit_ids(self, wire, name):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _get_all_commit_ids(_context_uid, _repo_id, _name):
            repo = self._factory.repo(wire)
            repo = repo.filtered(name)
            revs = [hex(x[7]) for x in repo.changelog.index]
            return revs
        return _get_all_commit_ids(context_uid, repo_id, name)

    @reraise_safe_exceptions
    def get_config_value(self, wire, section, name, untrusted=False):
        repo = self._factory.repo(wire)
        return repo.ui.config(section, name, untrusted=untrusted)

    @reraise_safe_exceptions
    def is_large_file(self, wire, commit_id, path):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _is_large_file(_context_uid, _repo_id, _commit_id, _path):
            return largefiles.lfutil.isstandin(path)

        return _is_large_file(context_uid, repo_id, commit_id, path)

    @reraise_safe_exceptions
    def is_binary(self, wire, revision, path):
        cache_on, context_uid, repo_id = self._cache_on(wire)

        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _is_binary(_repo_id, _sha, _path):
            repo = self._factory.repo(wire)
            ctx = self._get_ctx(repo, revision)
            fctx = ctx.filectx(path)
            return fctx.isbinary()

        return _is_binary(repo_id, revision, path)

    @reraise_safe_exceptions
    def in_largefiles_store(self, wire, sha):
        repo = self._factory.repo(wire)
        return largefiles.lfutil.instore(repo, sha)

    @reraise_safe_exceptions
    def in_user_cache(self, wire, sha):
        repo = self._factory.repo(wire)
        return largefiles.lfutil.inusercache(repo.ui, sha)

    @reraise_safe_exceptions
    def store_path(self, wire, sha):
        repo = self._factory.repo(wire)
        return largefiles.lfutil.storepath(repo, sha)

    @reraise_safe_exceptions
    def link(self, wire, sha, path):
        repo = self._factory.repo(wire)
        largefiles.lfutil.link(
            largefiles.lfutil.usercachepath(repo.ui, sha), path)

    @reraise_safe_exceptions
    def localrepository(self, wire, create=False):
        self._factory.repo(wire, create=create)

    @reraise_safe_exceptions
    def lookup(self, wire, revision, both):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _lookup(_context_uid, _repo_id, _revision, _both):

            repo = self._factory.repo(wire)
            rev = _revision
            if isinstance(rev, int):
                # NOTE(marcink):
                # since Mercurial doesn't support negative indexes properly
                # we need to shift accordingly by one to get proper index, e.g
                # repo[-1] => repo[-2]
                # repo[0]  => repo[-1]
                if rev <= 0:
                    rev = rev + -1
            try:
                ctx = self._get_ctx(repo, rev)
            except (TypeError, RepoLookupError) as e:
                e._org_exc_tb = traceback.format_exc()
                raise exceptions.LookupException(e)(rev)
            except LookupError as e:
                e._org_exc_tb = traceback.format_exc()
                raise exceptions.LookupException(e)(e.name)

            if not both:
                return ctx.hex()

            ctx = repo[ctx.hex()]
            return ctx.hex(), ctx.rev()

        return _lookup(context_uid, repo_id, revision, both)

    @reraise_safe_exceptions
    def sync_push(self, wire, url):
        if not self.check_url(url, wire['config']):
            return

        repo = self._factory.repo(wire)

        # Disable any prompts for this repo
        repo.ui.setconfig('ui', 'interactive', 'off', '-y')

        bookmarks = list(dict(repo._bookmarks).keys())
        remote = peer(repo, {}, url)
        # Disable any prompts for this remote
        remote.ui.setconfig('ui', 'interactive', 'off', '-y')

        return exchange.push(
            repo, remote, newbranch=True, bookmarks=bookmarks).cgresult

    @reraise_safe_exceptions
    def revision(self, wire, rev):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, rev)
        return ctx.rev()

    @reraise_safe_exceptions
    def rev_range(self, wire, commit_filter):
        cache_on, context_uid, repo_id = self._cache_on(wire)

        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _rev_range(_context_uid, _repo_id, _filter):
            repo = self._factory.repo(wire)
            revisions = [rev for rev in revrange(repo, commit_filter)]
            return revisions

        return _rev_range(context_uid, repo_id, sorted(commit_filter))

    @reraise_safe_exceptions
    def rev_range_hash(self, wire, node):
        repo = self._factory.repo(wire)

        def get_revs(repo, rev_opt):
            if rev_opt:
                revs = revrange(repo, rev_opt)
                if len(revs) == 0:
                    return (nullrev, nullrev)
                return max(revs), min(revs)
            else:
                return len(repo) - 1, 0

        stop, start = get_revs(repo, [node + ':'])
        revs = [hex(repo[r].node()) for r in range(start, stop + 1)]
        return revs

    @reraise_safe_exceptions
    def revs_from_revspec(self, wire, rev_spec, *args, **kwargs):
        other_path = kwargs.pop('other_path', None)

        # case when we want to compare two independent repositories
        if other_path and other_path != wire["path"]:
            baseui = self._factory._create_config(wire["config"])
            repo = unionrepo.makeunionrepository(baseui, other_path, wire["path"])
        else:
            repo = self._factory.repo(wire)
        return list(repo.revs(rev_spec, *args))

    @reraise_safe_exceptions
    def verify(self, wire,):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])

        baseui, output = patch_ui_message_output(baseui)

        repo.ui = baseui
        verify.verify(repo)
        return output.getvalue()

    @reraise_safe_exceptions
    def hg_update_cache(self, wire,):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        baseui, output = patch_ui_message_output(baseui)

        repo.ui = baseui
        with repo.wlock(), repo.lock():
            repo.updatecaches(full=True)

        return output.getvalue()

    @reraise_safe_exceptions
    def hg_rebuild_fn_cache(self, wire,):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        baseui, output = patch_ui_message_output(baseui)

        repo.ui = baseui

        repair.rebuildfncache(baseui, repo)

        return output.getvalue()

    @reraise_safe_exceptions
    def tags(self, wire):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        @self.region.conditional_cache_on_arguments(condition=cache_on)
        def _tags(_context_uid, _repo_id):
            repo = self._factory.repo(wire)
            return repo.tags()

        return _tags(context_uid, repo_id)

    @reraise_safe_exceptions
    def update(self, wire, node=None, clean=False):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        commands.update(baseui, repo, node=node, clean=clean)

    @reraise_safe_exceptions
    def identify(self, wire):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        output = io.BytesIO()
        baseui.write = output.write
        # This is required to get a full node id
        baseui.debugflag = True
        commands.identify(baseui, repo, id=True)

        return output.getvalue()

    @reraise_safe_exceptions
    def heads(self, wire, branch=None):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        output = io.BytesIO()

        def write(data, **unused_kwargs):
            output.write(data)

        baseui.write = write
        if branch:
            args = [branch]
        else:
            args = []
        commands.heads(baseui, repo, template='{node} ', *args)

        return output.getvalue()

    @reraise_safe_exceptions
    def ancestor(self, wire, revision1, revision2):
        repo = self._factory.repo(wire)
        changelog = repo.changelog
        lookup = repo.lookup
        a = changelog.ancestor(lookup(revision1), lookup(revision2))
        return hex(a)

    @reraise_safe_exceptions
    def clone(self, wire, source, dest, update_after_clone=False, hooks=True):
        baseui = self._factory._create_config(wire["config"], hooks=hooks)
        clone(baseui, source, dest, noupdate=not update_after_clone)

    @reraise_safe_exceptions
    def commitctx(self, wire, message, parents, commit_time, commit_timezone, user, files, extra, removed, updated):

        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        publishing = baseui.configbool('phases', 'publish')
        if publishing:
            new_commit = 'public'
        else:
            new_commit = 'draft'

        def _filectxfn(_repo, ctx, path):
            """
            Marks given path as added/changed/removed in a given _repo. This is
            for internal mercurial commit function.
            """

            # check if this path is removed
            if path in removed:
                # returning None is a way to mark node for removal
                return None

            # check if this path is added
            for node in updated:
                if node['path'] == path:
                    return memfilectx(
                        _repo,
                        changectx=ctx,
                        path=node['path'],
                        data=node['content'],
                        islink=False,
                        isexec=bool(node['mode'] & stat.S_IXUSR),
                        copysource=False)

            raise exceptions.AbortException()(
                "Given path haven't been marked as added, "
                "changed or removed (%s)" % path)

        with repo.ui.configoverride({('phases', 'new-commit'): new_commit}):

            commit_ctx = memctx(
                repo=repo,
                parents=parents,
                text=message,
                files=files,
                filectxfn=_filectxfn,
                user=user,
                date=(commit_time, commit_timezone),
                extra=extra)

            n = repo.commitctx(commit_ctx)
            new_id = hex(n)

            return new_id

    @reraise_safe_exceptions
    def pull(self, wire, url, commit_ids=None):
        repo = self._factory.repo(wire)
        # Disable any prompts for this repo
        repo.ui.setconfig('ui', 'interactive', 'off', '-y')

        remote = peer(repo, {}, url)
        # Disable any prompts for this remote
        remote.ui.setconfig('ui', 'interactive', 'off', '-y')

        if commit_ids:
            commit_ids = [bin(commit_id) for commit_id in commit_ids]

        return exchange.pull(
            repo, remote, heads=commit_ids, force=None).cgresult

    @reraise_safe_exceptions
    def pull_cmd(self, wire, source, bookmark=None, branch=None, revision=None, hooks=True):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'], hooks=hooks)

        # Mercurial internally has a lot of logic that checks ONLY if
        # option is defined, we just pass those if they are defined then
        opts = {}
        if bookmark:
            opts['bookmark'] = bookmark
        if branch:
            opts['branch'] = branch
        if revision:
            opts['rev'] = revision

        commands.pull(baseui, repo, source, **opts)

    @reraise_safe_exceptions
    def push(self, wire, revisions, dest_path, hooks=True, push_branches=False):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'], hooks=hooks)
        commands.push(baseui, repo, dest=dest_path, rev=revisions,
                      new_branch=push_branches)

    @reraise_safe_exceptions
    def strip(self, wire, revision, update, backup):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        hgext_strip(
            repo.baseui, repo, ctx.node(), update=update, backup=backup)

    @reraise_safe_exceptions
    def get_unresolved_files(self, wire):
        repo = self._factory.repo(wire)

        log.debug('Calculating unresolved files for repo: %s', repo)
        output = io.BytesIO()

        def write(data, **unused_kwargs):
            output.write(data)

        baseui = self._factory._create_config(wire['config'])
        baseui.write = write

        commands.resolve(baseui, repo, list=True)
        unresolved = output.getvalue().splitlines(0)
        return unresolved

    @reraise_safe_exceptions
    def merge(self, wire, revision):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        repo.ui.setconfig('ui', 'merge', 'internal:dump')

        # In case of sub repositories are used mercurial prompts the user in
        # case of merge conflicts or different sub repository sources. By
        # setting the interactive flag to `False` mercurial doesn't prompt the
        # used but instead uses a default value.
        repo.ui.setconfig('ui', 'interactive', False)
        commands.merge(baseui, repo, rev=revision)

    @reraise_safe_exceptions
    def merge_state(self, wire):
        repo = self._factory.repo(wire)
        repo.ui.setconfig('ui', 'merge', 'internal:dump')

        # In case of sub repositories are used mercurial prompts the user in
        # case of merge conflicts or different sub repository sources. By
        # setting the interactive flag to `False` mercurial doesn't prompt the
        # used but instead uses a default value.
        repo.ui.setconfig('ui', 'interactive', False)
        ms = hg_merge.mergestate(repo)
        return [x for x in ms.unresolved()]

    @reraise_safe_exceptions
    def commit(self, wire, message, username, close_branch=False):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        repo.ui.setconfig('ui', 'username', username)
        commands.commit(baseui, repo, message=message, close_branch=close_branch)

    @reraise_safe_exceptions
    def rebase(self, wire, source=None, dest=None, abort=False):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        repo.ui.setconfig('ui', 'merge', 'internal:dump')
        # In case of sub repositories are used mercurial prompts the user in
        # case of merge conflicts or different sub repository sources. By
        # setting the interactive flag to `False` mercurial doesn't prompt the
        # used but instead uses a default value.
        repo.ui.setconfig('ui', 'interactive', False)
        rebase.rebase(baseui, repo, base=source, dest=dest, abort=abort, keep=not abort)

    @reraise_safe_exceptions
    def tag(self, wire, name, revision, message, local, user, tag_time, tag_timezone):
        repo = self._factory.repo(wire)
        ctx = self._get_ctx(repo, revision)
        node = ctx.node()

        date = (tag_time, tag_timezone)
        try:
            hg_tag.tag(repo, name, node, message, local, user, date)
        except Abort as e:
            log.exception("Tag operation aborted")
            # Exception can contain unicode which we convert
            raise exceptions.AbortException(e)(repr(e))

    @reraise_safe_exceptions
    def bookmark(self, wire, bookmark, revision=None):
        repo = self._factory.repo(wire)
        baseui = self._factory._create_config(wire['config'])
        commands.bookmark(baseui, repo, bookmark, rev=revision, force=True)

    @reraise_safe_exceptions
    def install_hooks(self, wire, force=False):
        # we don't need any special hooks for Mercurial
        pass

    @reraise_safe_exceptions
    def get_hooks_info(self, wire):
        return {
            'pre_version': vcsserver.__version__,
            'post_version': vcsserver.__version__,
        }