narrow: move the ellipses server capability to core

This will be used in core logic to determining whether a server is ellipses
enabled or not. And also this will ease moving narrow related things to core.

Differential Revision: https://phab.mercurial-scm.org/D4809

hgext/narrow/narrowcommands.py

@@ -1,421 +1,417 b''
 # narrowcommands.py - command modifications for narrowhg extension
 #
 # Copyright 2017 Google, Inc.
 #
 # 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 itertools
 import os
 
 from mercurial.i18n import _
 from mercurial import (
     cmdutil,
     commands,
     discovery,
     encoding,
     error,
     exchange,
     extensions,
     hg,
     merge,
     narrowspec,
     node,
     pycompat,
     registrar,
     repair,
     repository,
     repoview,
     sparse,
     util,
     wireprotoserver,
 )
 
-from . import (
-    narrowwirepeer,
-)
-
 table = {}
 command = registrar.command(table)
 
 def setup():
     """Wraps user-facing mercurial commands with narrow-aware versions."""
 
     entry = extensions.wrapcommand(commands.table, 'clone', clonenarrowcmd)
     entry[1].append(('', 'narrow', None,
                      _("create a narrow clone of select files")))
     entry[1].append(('', 'depth', '',
                      _("limit the history fetched by distance from heads")))
     entry[1].append(('', 'narrowspec', '',
                      _("read narrowspecs from file")))
     # TODO(durin42): unify sparse/narrow --include/--exclude logic a bit
     if 'sparse' not in extensions.enabled():
         entry[1].append(('', 'include', [],
                          _("specifically fetch this file/directory")))
         entry[1].append(
             ('', 'exclude', [],
              _("do not fetch this file/directory, even if included")))
 
     entry = extensions.wrapcommand(commands.table, 'pull', pullnarrowcmd)
     entry[1].append(('', 'depth', '',
                      _("limit the history fetched by distance from heads")))
 
     extensions.wrapcommand(commands.table, 'archive', archivenarrowcmd)
 
 def clonenarrowcmd(orig, ui, repo, *args, **opts):
     """Wraps clone command, so 'hg clone' first wraps localrepo.clone()."""
     opts = pycompat.byteskwargs(opts)
     wrappedextraprepare = util.nullcontextmanager()
     narrowspecfile = opts['narrowspec']
 
     if narrowspecfile:
         filepath = os.path.join(encoding.getcwd(), narrowspecfile)
         ui.status(_("reading narrowspec from '%s'\n") % filepath)
         try:
             fdata = util.readfile(filepath)
         except IOError as inst:
             raise error.Abort(_("cannot read narrowspecs from '%s': %s") %
                               (filepath, encoding.strtolocal(inst.strerror)))
 
         includes, excludes, profiles = sparse.parseconfig(ui, fdata, 'narrow')
         if profiles:
             raise error.Abort(_("cannot specify other files using '%include' in"
                                 " narrowspec"))
 
         narrowspec.validatepatterns(includes)
         narrowspec.validatepatterns(excludes)
 
         # narrowspec is passed so we should assume that user wants narrow clone
         opts['narrow'] = True
         opts['include'].extend(includes)
         opts['exclude'].extend(excludes)
 
     if opts['narrow']:
         def pullbundle2extraprepare_widen(orig, pullop, kwargs):
             orig(pullop, kwargs)
 
             if opts.get('depth'):
                 kwargs['depth'] = opts['depth']
         wrappedextraprepare = extensions.wrappedfunction(exchange,
             '_pullbundle2extraprepare', pullbundle2extraprepare_widen)
 
     with wrappedextraprepare:
         return orig(ui, repo, *args, **pycompat.strkwargs(opts))
 
 def pullnarrowcmd(orig, ui, repo, *args, **opts):
     """Wraps pull command to allow modifying narrow spec."""
     wrappedextraprepare = util.nullcontextmanager()
     if repository.NARROW_REQUIREMENT in repo.requirements:
 
         def pullbundle2extraprepare_widen(orig, pullop, kwargs):
             orig(pullop, kwargs)
             if opts.get(r'depth'):
                 kwargs['depth'] = opts[r'depth']
         wrappedextraprepare = extensions.wrappedfunction(exchange,
             '_pullbundle2extraprepare', pullbundle2extraprepare_widen)
 
     with wrappedextraprepare:
         return orig(ui, repo, *args, **opts)
 
 def archivenarrowcmd(orig, ui, repo, *args, **opts):
     """Wraps archive command to narrow the default includes."""
     if repository.NARROW_REQUIREMENT in repo.requirements:
         repo_includes, repo_excludes = repo.narrowpats
         includes = set(opts.get(r'include', []))
         excludes = set(opts.get(r'exclude', []))
         includes, excludes, unused_invalid = narrowspec.restrictpatterns(
             includes, excludes, repo_includes, repo_excludes)
         if includes:
             opts[r'include'] = includes
         if excludes:
             opts[r'exclude'] = excludes
     return orig(ui, repo, *args, **opts)
 
 def pullbundle2extraprepare(orig, pullop, kwargs):
     repo = pullop.repo
     if repository.NARROW_REQUIREMENT not in repo.requirements:
         return orig(pullop, kwargs)
 
     if wireprotoserver.NARROWCAP not in pullop.remote.capabilities():
         raise error.Abort(_("server doesn't support narrow clones"))
     orig(pullop, kwargs)
     kwargs['narrow'] = True
     include, exclude = repo.narrowpats
     kwargs['oldincludepats'] = include
     kwargs['oldexcludepats'] = exclude
     kwargs['includepats'] = include
     kwargs['excludepats'] = exclude
     # calculate known nodes only in ellipses cases because in non-ellipses cases
     # we have all the nodes
-    if narrowwirepeer.ELLIPSESCAP in pullop.remote.capabilities():
+    if wireprotoserver.ELLIPSESCAP in pullop.remote.capabilities():
         kwargs['known'] = [node.hex(ctx.node()) for ctx in
                            repo.set('::%ln', pullop.common)
                            if ctx.node() != node.nullid]
         if not kwargs['known']:
             # Mercurial serializes an empty list as '' and deserializes it as
             # [''], so delete it instead to avoid handling the empty string on
             # the server.
             del kwargs['known']
 
 extensions.wrapfunction(exchange,'_pullbundle2extraprepare',
                         pullbundle2extraprepare)
 
 # This is an extension point for filesystems that need to do something other
 # than just blindly unlink the files. It's not clear what arguments would be
 # useful, so we're passing in a fair number of them, some of them redundant.
 def _narrowcleanupwdir(repo, oldincludes, oldexcludes, newincludes, newexcludes,
                        oldmatch, newmatch):
     for f in repo.dirstate:
         if not newmatch(f):
             repo.dirstate.drop(f)
             repo.wvfs.unlinkpath(f)
 
 def _narrow(ui, repo, remote, commoninc, oldincludes, oldexcludes,
             newincludes, newexcludes, force):
     oldmatch = narrowspec.match(repo.root, oldincludes, oldexcludes)
     newmatch = narrowspec.match(repo.root, newincludes, newexcludes)
 
     # This is essentially doing "hg outgoing" to find all local-only
     # commits. We will then check that the local-only commits don't
     # have any changes to files that will be untracked.
     unfi = repo.unfiltered()
     outgoing = discovery.findcommonoutgoing(unfi, remote,
                                             commoninc=commoninc)
     ui.status(_('looking for local changes to affected paths\n'))
     localnodes = []
     for n in itertools.chain(outgoing.missing, outgoing.excluded):
         if any(oldmatch(f) and not newmatch(f) for f in unfi[n].files()):
             localnodes.append(n)
     revstostrip = unfi.revs('descendants(%ln)', localnodes)
     hiddenrevs = repoview.filterrevs(repo, 'visible')
     visibletostrip = list(repo.changelog.node(r)
                           for r in (revstostrip - hiddenrevs))
     if visibletostrip:
         ui.status(_('The following changeset(s) or their ancestors have '
                     'local changes not on the remote:\n'))
         maxnodes = 10
         if ui.verbose or len(visibletostrip) <= maxnodes:
             for n in visibletostrip:
                 ui.status('%s\n' % node.short(n))
         else:
             for n in visibletostrip[:maxnodes]:
                 ui.status('%s\n' % node.short(n))
             ui.status(_('...and %d more, use --verbose to list all\n') %
                       (len(visibletostrip) - maxnodes))
         if not force:
             raise error.Abort(_('local changes found'),
                               hint=_('use --force-delete-local-changes to '
                                      'ignore'))
 
     with ui.uninterruptable():
         if revstostrip:
             tostrip = [unfi.changelog.node(r) for r in revstostrip]
             if repo['.'].node() in tostrip:
                 # stripping working copy, so move to a different commit first
                 urev = max(repo.revs('(::%n) - %ln + null',
                                      repo['.'].node(), visibletostrip))
                 hg.clean(repo, urev)
             repair.strip(ui, unfi, tostrip, topic='narrow')
 
         todelete = []
         for f, f2, size in repo.store.datafiles():
             if f.startswith('data/'):
                 file = f[5:-2]
                 if not newmatch(file):
                     todelete.append(f)
             elif f.startswith('meta/'):
                 dir = f[5:-13]
                 dirs = ['.'] + sorted(util.dirs({dir})) + [dir]
                 include = True
                 for d in dirs:
                     visit = newmatch.visitdir(d)
                     if not visit:
                         include = False
                         break
                     if visit == 'all':
                         break
                 if not include:
                     todelete.append(f)
 
         repo.destroying()
 
         with repo.transaction("narrowing"):
             for f in todelete:
                 ui.status(_('deleting %s\n') % f)
                 util.unlinkpath(repo.svfs.join(f))
                 repo.store.markremoved(f)
 
             _narrowcleanupwdir(repo, oldincludes, oldexcludes, newincludes,
                                newexcludes, oldmatch, newmatch)
             repo.setnarrowpats(newincludes, newexcludes)
 
         repo.destroyed()
 
 def _widen(ui, repo, remote, commoninc, newincludes, newexcludes):
     newmatch = narrowspec.match(repo.root, newincludes, newexcludes)
 
     def pullbundle2extraprepare_widen(orig, pullop, kwargs):
         orig(pullop, kwargs)
         # The old{in,ex}cludepats have already been set by orig()
         kwargs['includepats'] = newincludes
         kwargs['excludepats'] = newexcludes
         kwargs['widen'] = True
     wrappedextraprepare = extensions.wrappedfunction(exchange,
         '_pullbundle2extraprepare', pullbundle2extraprepare_widen)
 
     # define a function that narrowbundle2 can call after creating the
     # backup bundle, but before applying the bundle from the server
     def setnewnarrowpats():
         repo.setnarrowpats(newincludes, newexcludes)
     repo.setnewnarrowpats = setnewnarrowpats
     # silence the devel-warning of applying an empty changegroup
     overrides = {('devel', 'all-warnings'): False}
 
     with ui.uninterruptable():
         ds = repo.dirstate
         p1, p2 = ds.p1(), ds.p2()
         with ds.parentchange():
             ds.setparents(node.nullid, node.nullid)
         common = commoninc[0]
         with wrappedextraprepare, repo.ui.configoverride(overrides, 'widen'):
             exchange.pull(repo, remote, heads=common)
         with ds.parentchange():
             ds.setparents(p1, p2)
 
         repo.setnewnarrowpats()
         actions = {k: [] for k in 'a am f g cd dc r dm dg m e k p pr'.split()}
         addgaction = actions['g'].append
 
         mf = repo['.'].manifest().matches(newmatch)
         for f, fn in mf.iteritems():
             if f not in repo.dirstate:
                 addgaction((f, (mf.flags(f), False),
                             "add from widened narrow clone"))
 
         merge.applyupdates(repo, actions, wctx=repo[None],
                            mctx=repo['.'], overwrite=False)
         merge.recordupdates(repo, actions, branchmerge=False)
 
 # TODO(rdamazio): Make new matcher format and update description
 @command('tracked',
     [('', 'addinclude', [], _('new paths to include')),
      ('', 'removeinclude', [], _('old paths to no longer include')),
      ('', 'addexclude', [], _('new paths to exclude')),
      ('', 'import-rules', '', _('import narrowspecs from a file')),
      ('', 'removeexclude', [], _('old paths to no longer exclude')),
      ('', 'clear', False, _('whether to replace the existing narrowspec')),
      ('', 'force-delete-local-changes', False,
        _('forces deletion of local changes when narrowing')),
     ] + commands.remoteopts,
     _('[OPTIONS]... [REMOTE]'),
     inferrepo=True)
 def trackedcmd(ui, repo, remotepath=None, *pats, **opts):
     """show or change the current narrowspec
 
     With no argument, shows the current narrowspec entries, one per line. Each
     line will be prefixed with 'I' or 'X' for included or excluded patterns,
     respectively.
 
     The narrowspec is comprised of expressions to match remote files and/or
     directories that should be pulled into your client.
     The narrowspec has *include* and *exclude* expressions, with excludes always
     trumping includes: that is, if a file matches an exclude expression, it will
     be excluded even if it also matches an include expression.
     Excluding files that were never included has no effect.
 
     Each included or excluded entry is in the format described by
     'hg help patterns'.
 
     The options allow you to add or remove included and excluded expressions.
 
     If --clear is specified, then all previous includes and excludes are DROPPED
     and replaced by the new ones specified to --addinclude and --addexclude.
     If --clear is specified without any further options, the narrowspec will be
     empty and will not match any files.
     """
     opts = pycompat.byteskwargs(opts)
     if repository.NARROW_REQUIREMENT not in repo.requirements:
         ui.warn(_('The narrow command is only supported on respositories cloned'
                   ' with --narrow.\n'))
         return 1
 
     # Before supporting, decide whether it "hg tracked --clear" should mean
     # tracking no paths or all paths.
     if opts['clear']:
         ui.warn(_('The --clear option is not yet supported.\n'))
         return 1
 
     # import rules from a file
     newrules = opts.get('import_rules')
     if newrules:
         try:
             filepath = os.path.join(encoding.getcwd(), newrules)
             fdata = util.readfile(filepath)
         except IOError as inst:
             raise error.Abort(_("cannot read narrowspecs from '%s': %s") %
                               (filepath, encoding.strtolocal(inst.strerror)))
         includepats, excludepats, profiles = sparse.parseconfig(ui, fdata,
                                                                 'narrow')
         if profiles:
             raise error.Abort(_("including other spec files using '%include' "
                                 "is not supported in narrowspec"))
         opts['addinclude'].extend(includepats)
         opts['addexclude'].extend(excludepats)
 
     addedincludes = narrowspec.parsepatterns(opts['addinclude'])
     removedincludes = narrowspec.parsepatterns(opts['removeinclude'])
     addedexcludes = narrowspec.parsepatterns(opts['addexclude'])
     removedexcludes = narrowspec.parsepatterns(opts['removeexclude'])
     widening = addedincludes or removedexcludes
     narrowing = removedincludes or addedexcludes
     only_show = not widening and not narrowing
 
     # Only print the current narrowspec.
     if only_show:
         include, exclude = repo.narrowpats
 
         ui.pager('tracked')
         fm = ui.formatter('narrow', opts)
         for i in sorted(include):
             fm.startitem()
             fm.write('status', '%s ', 'I', label='narrow.included')
             fm.write('pat', '%s\n', i, label='narrow.included')
         for i in sorted(exclude):
             fm.startitem()
             fm.write('status', '%s ', 'X', label='narrow.excluded')
             fm.write('pat', '%s\n', i, label='narrow.excluded')
         fm.end()
         return 0
 
     with repo.wlock(), repo.lock():
         cmdutil.bailifchanged(repo)
 
         # Find the revisions we have in common with the remote. These will
         # be used for finding local-only changes for narrowing. They will
         # also define the set of revisions to update for widening.
         remotepath = ui.expandpath(remotepath or 'default')
         url, branches = hg.parseurl(remotepath)
         ui.status(_('comparing with %s\n') % util.hidepassword(url))
         remote = hg.peer(repo, opts, url)
         commoninc = discovery.findcommonincoming(repo, remote)
 
         oldincludes, oldexcludes = repo.narrowpats
         if narrowing:
             newincludes = oldincludes - removedincludes
             newexcludes = oldexcludes | addedexcludes
             _narrow(ui, repo, remote, commoninc, oldincludes, oldexcludes,
                     newincludes, newexcludes,
                     opts['force_delete_local_changes'])
             # _narrow() updated the narrowspec and _widen() below needs to
             # use the updated values as its base (otherwise removed includes
             # and addedexcludes will be lost in the resulting narrowspec)
             oldincludes = newincludes
             oldexcludes = newexcludes
 
         if widening:
             newincludes = oldincludes | addedincludes
             newexcludes = oldexcludes - removedexcludes
             _widen(ui, repo, remote, commoninc, newincludes, newexcludes)
 
     return 0

hgext/narrow/narrowrepo.py

@@ -1,34 +1,33 b''
 # narrowrepo.py - repository which supports narrow revlogs, lazy loading
 #
 # Copyright 2017 Google, Inc.
 #
 # 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 mercurial import (
     wireprotoserver,
 )
 
 from . import (
     narrowdirstate,
-    narrowwirepeer,
 )
 
 def wraprepo(repo):
     """Enables narrow clone functionality on a single local repository."""
 
     class narrowrepository(repo.__class__):
 
         def _makedirstate(self):
             dirstate = super(narrowrepository, self)._makedirstate()
             return narrowdirstate.wrapdirstate(self, dirstate)
 
         def peer(self):
             peer = super(narrowrepository, self).peer()
             peer._caps.add(wireprotoserver.NARROWCAP)
-            peer._caps.add(narrowwirepeer.ELLIPSESCAP)
+            peer._caps.add(wireprotoserver.ELLIPSESCAP)
             return peer
 
     repo.__class__ = narrowrepository

hgext/narrow/narrowwirepeer.py

@@ -1,41 +1,39 b''
 # narrowwirepeer.py - passes narrow spec with unbundle command
 #
 # Copyright 2017 Google, Inc.
 #
 # 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 mercurial import (
     extensions,
     hg,
     wireprotoserver,
     wireprotov1server,
 )
 
-ELLIPSESCAP = 'exp-ellipses-1'
-
 def uisetup():
     extensions.wrapfunction(wireprotov1server, '_capabilities', addnarrowcap)
 
 def addnarrowcap(orig, repo, proto):
     """add the narrow capability to the server"""
     caps = orig(repo, proto)
     caps.append(wireprotoserver.NARROWCAP)
     if repo.ui.configbool('experimental', 'narrowservebrokenellipses'):
-        caps.append(ELLIPSESCAP)
+        caps.append(wireprotoserver.ELLIPSESCAP)
     return caps
 
 def reposetup(repo):
     def wirereposetup(ui, peer):
         def wrapped(orig, cmd, *args, **kwargs):
             if cmd == 'unbundle':
                 # TODO: don't blindly add include/exclude wireproto
                 # arguments to unbundle.
                 include, exclude = repo.narrowpats
                 kwargs[r"includepats"] = ','.join(include)
                 kwargs[r"excludepats"] = ','.join(exclude)
             return orig(cmd, *args, **kwargs)
         extensions.wrapfunction(peer, '_calltwowaystream', wrapped)
     hg.wirepeersetupfuncs.append(wirereposetup)

mercurial/wireprotoserver.py

@@ -1,806 +1,807 b''
 # Copyright 21 May 2005 - (c) 2005 Jake Edge <[e-mail]>
 # Copyright 2005-2007 Matt Mackall <[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 contextlib
 import struct
 import sys
 import threading
 
 from .i18n import _
 from . import (
     encoding,
     error,
     pycompat,
     util,
     wireprototypes,
     wireprotov1server,
     wireprotov2server,
 )
 from .utils import (
     cborutil,
     interfaceutil,
     procutil,
 )
 
 stringio = util.stringio
 
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 HTTP_OK = 200
 
 HGTYPE = 'application/mercurial-0.1'
 HGTYPE2 = 'application/mercurial-0.2'
 HGERRTYPE = 'application/hg-error'
 
 NARROWCAP = 'exp-narrow-1'
+ELLIPSESCAP = 'exp-ellipses-1'
 
 SSHV1 = wireprototypes.SSHV1
 SSHV2 = wireprototypes.SSHV2
 
 def decodevaluefromheaders(req, headerprefix):
     """Decode a long value from multiple HTTP request headers.
 
     Returns the value as a bytes, not a str.
     """
     chunks = []
     i = 1
     while True:
         v = req.headers.get(b'%s-%d' % (headerprefix, i))
         if v is None:
             break
         chunks.append(pycompat.bytesurl(v))
         i += 1
 
     return ''.join(chunks)
 
 @interfaceutil.implementer(wireprototypes.baseprotocolhandler)
 class httpv1protocolhandler(object):
     def __init__(self, req, ui, checkperm):
         self._req = req
         self._ui = ui
         self._checkperm = checkperm
         self._protocaps = None
 
     @property
     def name(self):
         return 'http-v1'
 
     def getargs(self, args):
         knownargs = self._args()
         data = {}
         keys = args.split()
         for k in keys:
             if k == '*':
                 star = {}
                 for key in knownargs.keys():
                     if key != 'cmd' and key not in keys:
                         star[key] = knownargs[key][0]
                 data['*'] = star
             else:
                 data[k] = knownargs[k][0]
         return [data[k] for k in keys]
 
     def _args(self):
         args = self._req.qsparams.asdictoflists()
         postlen = int(self._req.headers.get(b'X-HgArgs-Post', 0))
         if postlen:
             args.update(urlreq.parseqs(
                 self._req.bodyfh.read(postlen), keep_blank_values=True))
             return args
 
         argvalue = decodevaluefromheaders(self._req, b'X-HgArg')
         args.update(urlreq.parseqs(argvalue, keep_blank_values=True))
         return args
 
     def getprotocaps(self):
         if self._protocaps is None:
             value = decodevaluefromheaders(self._req, b'X-HgProto')
             self._protocaps = set(value.split(' '))
         return self._protocaps
 
     def getpayload(self):
         # Existing clients *always* send Content-Length.
         length = int(self._req.headers[b'Content-Length'])
 
         # If httppostargs is used, we need to read Content-Length
         # minus the amount that was consumed by args.
         length -= int(self._req.headers.get(b'X-HgArgs-Post', 0))
         return util.filechunkiter(self._req.bodyfh, limit=length)
 
     @contextlib.contextmanager
     def mayberedirectstdio(self):
         oldout = self._ui.fout
         olderr = self._ui.ferr
 
         out = util.stringio()
 
         try:
             self._ui.fout = out
             self._ui.ferr = out
             yield out
         finally:
             self._ui.fout = oldout
             self._ui.ferr = olderr
 
     def client(self):
         return 'remote:%s:%s:%s' % (
             self._req.urlscheme,
             urlreq.quote(self._req.remotehost or ''),
             urlreq.quote(self._req.remoteuser or ''))
 
     def addcapabilities(self, repo, caps):
         caps.append(b'batch')
 
         caps.append('httpheader=%d' %
                     repo.ui.configint('server', 'maxhttpheaderlen'))
         if repo.ui.configbool('experimental', 'httppostargs'):
             caps.append('httppostargs')
 
         # FUTURE advertise 0.2rx once support is implemented
         # FUTURE advertise minrx and mintx after consulting config option
         caps.append('httpmediatype=0.1rx,0.1tx,0.2tx')
 
         compengines = wireprototypes.supportedcompengines(repo.ui,
                                                           util.SERVERROLE)
         if compengines:
             comptypes = ','.join(urlreq.quote(e.wireprotosupport().name)
                                  for e in compengines)
             caps.append('compression=%s' % comptypes)
 
         return caps
 
     def checkperm(self, perm):
         return self._checkperm(perm)
 
 # This method exists mostly so that extensions like remotefilelog can
 # disable a kludgey legacy method only over http. As of early 2018,
 # there are no other known users, so with any luck we can discard this
 # hook if remotefilelog becomes a first-party extension.
 def iscmd(cmd):
     return cmd in wireprotov1server.commands
 
 def handlewsgirequest(rctx, req, res, checkperm):
     """Possibly process a wire protocol request.
 
     If the current request is a wire protocol request, the request is
     processed by this function.
 
     ``req`` is a ``parsedrequest`` instance.
     ``res`` is a ``wsgiresponse`` instance.
 
     Returns a bool indicating if the request was serviced. If set, the caller
     should stop processing the request, as a response has already been issued.
     """
     # Avoid cycle involving hg module.
     from .hgweb import common as hgwebcommon
 
     repo = rctx.repo
 
     # HTTP version 1 wire protocol requests are denoted by a "cmd" query
     # string parameter. If it isn't present, this isn't a wire protocol
     # request.
     if 'cmd' not in req.qsparams:
         return False
 
     cmd = req.qsparams['cmd']
 
     # The "cmd" request parameter is used by both the wire protocol and hgweb.
     # While not all wire protocol commands are available for all transports,
     # if we see a "cmd" value that resembles a known wire protocol command, we
     # route it to a protocol handler. This is better than routing possible
     # wire protocol requests to hgweb because it prevents hgweb from using
     # known wire protocol commands and it is less confusing for machine
     # clients.
     if not iscmd(cmd):
         return False
 
     # The "cmd" query string argument is only valid on the root path of the
     # repo. e.g. ``/?cmd=foo``, ``/repo?cmd=foo``. URL paths within the repo
     # like ``/blah?cmd=foo`` are not allowed. So don't recognize the request
     # in this case. We send an HTTP 404 for backwards compatibility reasons.
     if req.dispatchpath:
         res.status = hgwebcommon.statusmessage(404)
         res.headers['Content-Type'] = HGTYPE
         # TODO This is not a good response to issue for this request. This
         # is mostly for BC for now.
         res.setbodybytes('0\n%s\n' % b'Not Found')
         return True
 
     proto = httpv1protocolhandler(req, repo.ui,
                                   lambda perm: checkperm(rctx, req, perm))
 
     # The permissions checker should be the only thing that can raise an
     # ErrorResponse. It is kind of a layer violation to catch an hgweb
     # exception here. So consider refactoring into a exception type that
     # is associated with the wire protocol.
     try:
         _callhttp(repo, req, res, proto, cmd)
     except hgwebcommon.ErrorResponse as e:
         for k, v in e.headers:
             res.headers[k] = v
         res.status = hgwebcommon.statusmessage(e.code, pycompat.bytestr(e))
         # TODO This response body assumes the failed command was
         # "unbundle." That assumption is not always valid.
         res.setbodybytes('0\n%s\n' % pycompat.bytestr(e))
 
     return True
 
 def _availableapis(repo):
     apis = set()
 
     # Registered APIs are made available via config options of the name of
     # the protocol.
     for k, v in API_HANDLERS.items():
         section, option = v['config']
         if repo.ui.configbool(section, option):
             apis.add(k)
 
     return apis
 
 def handlewsgiapirequest(rctx, req, res, checkperm):
     """Handle requests to /api/*."""
     assert req.dispatchparts[0] == b'api'
 
     repo = rctx.repo
 
     # This whole URL space is experimental for now. But we want to
     # reserve the URL space. So, 404 all URLs if the feature isn't enabled.
     if not repo.ui.configbool('experimental', 'web.apiserver'):
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('Experimental API server endpoint not enabled'))
         return
 
     # The URL space is /api/<protocol>/*. The structure of URLs under varies
     # by <protocol>.
 
     availableapis = _availableapis(repo)
 
     # Requests to /api/ list available APIs.
     if req.dispatchparts == [b'api']:
         res.status = b'200 OK'
         res.headers[b'Content-Type'] = b'text/plain'
         lines = [_('APIs can be accessed at /api/<name>, where <name> can be '
                    'one of the following:\n')]
         if availableapis:
             lines.extend(sorted(availableapis))
         else:
             lines.append(_('(no available APIs)\n'))
         res.setbodybytes(b'\n'.join(lines))
         return
 
     proto = req.dispatchparts[1]
 
     if proto not in API_HANDLERS:
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('Unknown API: %s\nKnown APIs: %s') % (
             proto, b', '.join(sorted(availableapis))))
         return
 
     if proto not in availableapis:
         res.status = b'404 Not Found'
         res.headers[b'Content-Type'] = b'text/plain'
         res.setbodybytes(_('API %s not enabled\n') % proto)
         return
 
     API_HANDLERS[proto]['handler'](rctx, req, res, checkperm,
                                    req.dispatchparts[2:])
 
 # Maps API name to metadata so custom API can be registered.
 # Keys are:
 #
 # config
 #    Config option that controls whether service is enabled.
 # handler
 #    Callable receiving (rctx, req, res, checkperm, urlparts) that is called
 #    when a request to this API is received.
 # apidescriptor
 #    Callable receiving (req, repo) that is called to obtain an API
 #    descriptor for this service. The response must be serializable to CBOR.
 API_HANDLERS = {
     wireprotov2server.HTTP_WIREPROTO_V2: {
         'config': ('experimental', 'web.api.http-v2'),
         'handler': wireprotov2server.handlehttpv2request,
         'apidescriptor': wireprotov2server.httpv2apidescriptor,
     },
 }
 
 def _httpresponsetype(ui, proto, prefer_uncompressed):
     """Determine the appropriate response type and compression settings.
 
     Returns a tuple of (mediatype, compengine, engineopts).
     """
     # Determine the response media type and compression engine based
     # on the request parameters.
 
     if '0.2' in proto.getprotocaps():
         # All clients are expected to support uncompressed data.
         if prefer_uncompressed:
             return HGTYPE2, util._noopengine(), {}
 
         # Now find an agreed upon compression format.
         compformats = wireprotov1server.clientcompressionsupport(proto)
         for engine in wireprototypes.supportedcompengines(ui, util.SERVERROLE):
             if engine.wireprotosupport().name in compformats:
                 opts = {}
                 level = ui.configint('server', '%slevel' % engine.name())
                 if level is not None:
                     opts['level'] = level
 
                 return HGTYPE2, engine, opts
 
         # No mutually supported compression format. Fall back to the
         # legacy protocol.
 
     # Don't allow untrusted settings because disabling compression or
     # setting a very high compression level could lead to flooding
     # the server's network or CPU.
     opts = {'level': ui.configint('server', 'zliblevel')}
     return HGTYPE, util.compengines['zlib'], opts
 
 def processcapabilitieshandshake(repo, req, res, proto):
     """Called during a ?cmd=capabilities request.
 
     If the client is advertising support for a newer protocol, we send
     a CBOR response with information about available services. If no
     advertised services are available, we don't handle the request.
     """
     # Fall back to old behavior unless the API server is enabled.
     if not repo.ui.configbool('experimental', 'web.apiserver'):
         return False
 
     clientapis = decodevaluefromheaders(req, b'X-HgUpgrade')
     protocaps = decodevaluefromheaders(req, b'X-HgProto')
     if not clientapis or not protocaps:
         return False
 
     # We currently only support CBOR responses.
     protocaps = set(protocaps.split(' '))
     if b'cbor' not in protocaps:
         return False
 
     descriptors = {}
 
     for api in sorted(set(clientapis.split()) & _availableapis(repo)):
         handler = API_HANDLERS[api]
 
         descriptorfn = handler.get('apidescriptor')
         if not descriptorfn:
             continue
 
         descriptors[api] = descriptorfn(req, repo)
 
     v1caps = wireprotov1server.dispatch(repo, proto, 'capabilities')
     assert isinstance(v1caps, wireprototypes.bytesresponse)
 
     m = {
         # TODO allow this to be configurable.
         'apibase': 'api/',
         'apis': descriptors,
         'v1capabilities': v1caps.data,
     }
 
     res.status = b'200 OK'
     res.headers[b'Content-Type'] = b'application/mercurial-cbor'
     res.setbodybytes(b''.join(cborutil.streamencode(m)))
 
     return True
 
 def _callhttp(repo, req, res, proto, cmd):
     # Avoid cycle involving hg module.
     from .hgweb import common as hgwebcommon
 
     def genversion2(gen, engine, engineopts):
         # application/mercurial-0.2 always sends a payload header
         # identifying the compression engine.
         name = engine.wireprotosupport().name
         assert 0 < len(name) < 256
         yield struct.pack('B', len(name))
         yield name
 
         for chunk in gen:
             yield chunk
 
     def setresponse(code, contenttype, bodybytes=None, bodygen=None):
         if code == HTTP_OK:
             res.status = '200 Script output follows'
         else:
             res.status = hgwebcommon.statusmessage(code)
 
         res.headers['Content-Type'] = contenttype
 
         if bodybytes is not None:
             res.setbodybytes(bodybytes)
         if bodygen is not None:
             res.setbodygen(bodygen)
 
     if not wireprotov1server.commands.commandavailable(cmd, proto):
         setresponse(HTTP_OK, HGERRTYPE,
                     _('requested wire protocol command is not available over '
                       'HTTP'))
         return
 
     proto.checkperm(wireprotov1server.commands[cmd].permission)
 
     # Possibly handle a modern client wanting to switch protocols.
     if (cmd == 'capabilities' and
         processcapabilitieshandshake(repo, req, res, proto)):
 
         return
 
     rsp = wireprotov1server.dispatch(repo, proto, cmd)
 
     if isinstance(rsp, bytes):
         setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.bytesresponse):
         setresponse(HTTP_OK, HGTYPE, bodybytes=rsp.data)
     elif isinstance(rsp, wireprototypes.streamreslegacy):
         setresponse(HTTP_OK, HGTYPE, bodygen=rsp.gen)
     elif isinstance(rsp, wireprototypes.streamres):
         gen = rsp.gen
 
         # This code for compression should not be streamres specific. It
         # is here because we only compress streamres at the moment.
         mediatype, engine, engineopts = _httpresponsetype(
             repo.ui, proto, rsp.prefer_uncompressed)
         gen = engine.compressstream(gen, engineopts)
 
         if mediatype == HGTYPE2:
             gen = genversion2(gen, engine, engineopts)
 
         setresponse(HTTP_OK, mediatype, bodygen=gen)
     elif isinstance(rsp, wireprototypes.pushres):
         rsp = '%d\n%s' % (rsp.res, rsp.output)
         setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.pusherr):
         rsp = '0\n%s\n' % rsp.res
         res.drain = True
         setresponse(HTTP_OK, HGTYPE, bodybytes=rsp)
     elif isinstance(rsp, wireprototypes.ooberror):
         setresponse(HTTP_OK, HGERRTYPE, bodybytes=rsp.message)
     else:
         raise error.ProgrammingError('hgweb.protocol internal failure', rsp)
 
 def _sshv1respondbytes(fout, value):
     """Send a bytes response for protocol version 1."""
     fout.write('%d\n' % len(value))
     fout.write(value)
     fout.flush()
 
 def _sshv1respondstream(fout, source):
     write = fout.write
     for chunk in source.gen:
         write(chunk)
     fout.flush()
 
 def _sshv1respondooberror(fout, ferr, rsp):
     ferr.write(b'%s\n-\n' % rsp)
     ferr.flush()
     fout.write(b'\n')
     fout.flush()
 
 @interfaceutil.implementer(wireprototypes.baseprotocolhandler)
 class sshv1protocolhandler(object):
     """Handler for requests services via version 1 of SSH protocol."""
     def __init__(self, ui, fin, fout):
         self._ui = ui
         self._fin = fin
         self._fout = fout
         self._protocaps = set()
 
     @property
     def name(self):
         return wireprototypes.SSHV1
 
     def getargs(self, args):
         data = {}
         keys = args.split()
         for n in pycompat.xrange(len(keys)):
             argline = self._fin.readline()[:-1]
             arg, l = argline.split()
             if arg not in keys:
                 raise error.Abort(_("unexpected parameter %r") % arg)
             if arg == '*':
                 star = {}
                 for k in pycompat.xrange(int(l)):
                     argline = self._fin.readline()[:-1]
                     arg, l = argline.split()
                     val = self._fin.read(int(l))
                     star[arg] = val
                 data['*'] = star
             else:
                 val = self._fin.read(int(l))
                 data[arg] = val
         return [data[k] for k in keys]
 
     def getprotocaps(self):
         return self._protocaps
 
     def getpayload(self):
         # We initially send an empty response. This tells the client it is
         # OK to start sending data. If a client sees any other response, it
         # interprets it as an error.
         _sshv1respondbytes(self._fout, b'')
 
         # The file is in the form:
         #
         # <chunk size>\n<chunk>
         # ...
         # 0\n
         count = int(self._fin.readline())
         while count:
             yield self._fin.read(count)
             count = int(self._fin.readline())
 
     @contextlib.contextmanager
     def mayberedirectstdio(self):
         yield None
 
     def client(self):
         client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0]
         return 'remote:ssh:' + client
 
     def addcapabilities(self, repo, caps):
         if self.name == wireprototypes.SSHV1:
             caps.append(b'protocaps')
         caps.append(b'batch')
         return caps
 
     def checkperm(self, perm):
         pass
 
 class sshv2protocolhandler(sshv1protocolhandler):
     """Protocol handler for version 2 of the SSH protocol."""
 
     @property
     def name(self):
         return wireprototypes.SSHV2
 
     def addcapabilities(self, repo, caps):
         return caps
 
 def _runsshserver(ui, repo, fin, fout, ev):
     # This function operates like a state machine of sorts. The following
     # states are defined:
     #
     # protov1-serving
     #    Server is in protocol version 1 serving mode. Commands arrive on
     #    new lines. These commands are processed in this state, one command
     #    after the other.
     #
     # protov2-serving
     #    Server is in protocol version 2 serving mode.
     #
     # upgrade-initial
     #    The server is going to process an upgrade request.
     #
     # upgrade-v2-filter-legacy-handshake
     #    The protocol is being upgraded to version 2. The server is expecting
     #    the legacy handshake from version 1.
     #
     # upgrade-v2-finish
     #    The upgrade to version 2 of the protocol is imminent.
     #
     # shutdown
     #    The server is shutting down, possibly in reaction to a client event.
     #
     # And here are their transitions:
     #
     # protov1-serving -> shutdown
     #    When server receives an empty request or encounters another
     #    error.
     #
     # protov1-serving -> upgrade-initial
     #    An upgrade request line was seen.
     #
     # upgrade-initial -> upgrade-v2-filter-legacy-handshake
     #    Upgrade to version 2 in progress. Server is expecting to
     #    process a legacy handshake.
     #
     # upgrade-v2-filter-legacy-handshake -> shutdown
     #    Client did not fulfill upgrade handshake requirements.
     #
     # upgrade-v2-filter-legacy-handshake -> upgrade-v2-finish
     #    Client fulfilled version 2 upgrade requirements. Finishing that
     #    upgrade.
     #
     # upgrade-v2-finish -> protov2-serving
     #    Protocol upgrade to version 2 complete. Server can now speak protocol
     #    version 2.
     #
     # protov2-serving -> protov1-serving
     #    Ths happens by default since protocol version 2 is the same as
     #    version 1 except for the handshake.
 
     state = 'protov1-serving'
     proto = sshv1protocolhandler(ui, fin, fout)
     protoswitched = False
 
     while not ev.is_set():
         if state == 'protov1-serving':
             # Commands are issued on new lines.
             request = fin.readline()[:-1]
 
             # Empty lines signal to terminate the connection.
             if not request:
                 state = 'shutdown'
                 continue
 
             # It looks like a protocol upgrade request. Transition state to
             # handle it.
             if request.startswith(b'upgrade '):
                 if protoswitched:
                     _sshv1respondooberror(fout, ui.ferr,
                                           b'cannot upgrade protocols multiple '
                                           b'times')
                     state = 'shutdown'
                     continue
 
                 state = 'upgrade-initial'
                 continue
 
             available = wireprotov1server.commands.commandavailable(
                 request, proto)
 
             # This command isn't available. Send an empty response and go
             # back to waiting for a new command.
             if not available:
                 _sshv1respondbytes(fout, b'')
                 continue
 
             rsp = wireprotov1server.dispatch(repo, proto, request)
 
             if isinstance(rsp, bytes):
                 _sshv1respondbytes(fout, rsp)
             elif isinstance(rsp, wireprototypes.bytesresponse):
                 _sshv1respondbytes(fout, rsp.data)
             elif isinstance(rsp, wireprototypes.streamres):
                 _sshv1respondstream(fout, rsp)
             elif isinstance(rsp, wireprototypes.streamreslegacy):
                 _sshv1respondstream(fout, rsp)
             elif isinstance(rsp, wireprototypes.pushres):
                 _sshv1respondbytes(fout, b'')
                 _sshv1respondbytes(fout, b'%d' % rsp.res)
             elif isinstance(rsp, wireprototypes.pusherr):
                 _sshv1respondbytes(fout, rsp.res)
             elif isinstance(rsp, wireprototypes.ooberror):
                 _sshv1respondooberror(fout, ui.ferr, rsp.message)
             else:
                 raise error.ProgrammingError('unhandled response type from '
                                              'wire protocol command: %s' % rsp)
 
         # For now, protocol version 2 serving just goes back to version 1.
         elif state == 'protov2-serving':
             state = 'protov1-serving'
             continue
 
         elif state == 'upgrade-initial':
             # We should never transition into this state if we've switched
             # protocols.
             assert not protoswitched
             assert proto.name == wireprototypes.SSHV1
 
             # Expected: upgrade <token> <capabilities>
             # If we get something else, the request is malformed. It could be
             # from a future client that has altered the upgrade line content.
             # We treat this as an unknown command.
             try:
                 token, caps = request.split(b' ')[1:]
             except ValueError:
                 _sshv1respondbytes(fout, b'')
                 state = 'protov1-serving'
                 continue
 
             # Send empty response if we don't support upgrading protocols.
             if not ui.configbool('experimental', 'sshserver.support-v2'):
                 _sshv1respondbytes(fout, b'')
                 state = 'protov1-serving'
                 continue
 
             try:
                 caps = urlreq.parseqs(caps)
             except ValueError:
                 _sshv1respondbytes(fout, b'')
                 state = 'protov1-serving'
                 continue
 
             # We don't see an upgrade request to protocol version 2. Ignore
             # the upgrade request.
             wantedprotos = caps.get(b'proto', [b''])[0]
             if SSHV2 not in wantedprotos:
                 _sshv1respondbytes(fout, b'')
                 state = 'protov1-serving'
                 continue
 
             # It looks like we can honor this upgrade request to protocol 2.
             # Filter the rest of the handshake protocol request lines.
             state = 'upgrade-v2-filter-legacy-handshake'
             continue
 
         elif state == 'upgrade-v2-filter-legacy-handshake':
             # Client should have sent legacy handshake after an ``upgrade``
             # request. Expected lines:
             #
             #    hello
             #    between
             #    pairs 81
             #    0000...-0000...
 
             ok = True
             for line in (b'hello', b'between', b'pairs 81'):
                 request = fin.readline()[:-1]
 
                 if request != line:
                     _sshv1respondooberror(fout, ui.ferr,
                                           b'malformed handshake protocol: '
                                           b'missing %s' % line)
                     ok = False
                     state = 'shutdown'
                     break
 
             if not ok:
                 continue
 
             request = fin.read(81)
             if request != b'%s-%s' % (b'0' * 40, b'0' * 40):
                 _sshv1respondooberror(fout, ui.ferr,
                                       b'malformed handshake protocol: '
                                       b'missing between argument value')
                 state = 'shutdown'
                 continue
 
             state = 'upgrade-v2-finish'
             continue
 
         elif state == 'upgrade-v2-finish':
             # Send the upgrade response.
             fout.write(b'upgraded %s %s\n' % (token, SSHV2))
             servercaps = wireprotov1server.capabilities(repo, proto)
             rsp = b'capabilities: %s' % servercaps.data
             fout.write(b'%d\n%s\n' % (len(rsp), rsp))
             fout.flush()
 
             proto = sshv2protocolhandler(ui, fin, fout)
             protoswitched = True
 
             state = 'protov2-serving'
             continue
 
         elif state == 'shutdown':
             break
 
         else:
             raise error.ProgrammingError('unhandled ssh server state: %s' %
                                          state)
 
 class sshserver(object):
     def __init__(self, ui, repo, logfh=None):
         self._ui = ui
         self._repo = repo
         self._fin, self._fout = procutil.protectstdio(ui.fin, ui.fout)
         # TODO: manage the redirection flag internally by ui
         ui._finoutredirected = (self._fin, self._fout) != (ui.fin, ui.fout)
 
         # Log write I/O to stdout and stderr if configured.
         if logfh:
             self._fout = util.makeloggingfileobject(
                 logfh, self._fout, 'o', logdata=True)
             ui.ferr = util.makeloggingfileobject(
                 logfh, ui.ferr, 'e', logdata=True)
 
     def serve_forever(self):
         self.serveuntil(threading.Event())
         procutil.restorestdio(self._ui.fin, self._ui.fout,
                               self._fin, self._fout)
         sys.exit(0)
 
     def serveuntil(self, ev):
         """Serve until a threading.Event is set."""
         _runsshserver(self._ui, self._repo, self._fin, self._fout, ev)