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 functools
import io
import logging
import os
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, archive_repo, ArchiveNode
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,
    alwaysmatcher, patternmatcher, hgutil)
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 bookmarks(self, wire):
        cache_on, context_uid, repo_id = self._cache_on(wire)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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)

        region = self._region(wire)
        @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)

        region = self._region(wire)
        @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)

        region = self._region(wire)
        @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)
        region = self._region(wire)
        @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__,
        }

    @reraise_safe_exceptions
    def set_head_ref(self, wire, head_name):
        pass

    @reraise_safe_exceptions
    def archive_repo(self, wire, archive_dest_path, kind, mtime, archive_at_path,
                     archive_dir_name, commit_id):

        def file_walker(_commit_id, path):
            repo = self._factory.repo(wire)
            ctx = repo[_commit_id]
            is_root = path in ['', '/']
            if is_root:
                matcher = alwaysmatcher(badfn=None)
            else:
                matcher = patternmatcher('', [(b'glob', path+'/**', b'')], badfn=None)
            file_iter = ctx.manifest().walk(matcher)

            for fn in file_iter:
                file_path = fn
                flags = ctx.flags(fn)
                mode = b'x' in flags and 0o755 or 0o644
                is_link = b'l' in flags

                yield ArchiveNode(file_path, mode, is_link, ctx[fn].data)

        return archive_repo(file_walker, archive_dest_path, kind, mtime, archive_at_path,
                            archive_dir_name, commit_id)