phabricator: refactor `phabread` to write all patches at once

This will be necessary to create a first class `phabimport` command.  That
command requires a transaction, and will import all named patches within a
single transaction.  But if Phabricator queries also happen within the
transaction, that leaves open the chance that an exception is raised, the
transaction is abandoned, and the next command that is run will complain about
needing to run `hg recover`.

Differential Revision: https://phab.mercurial-scm.org/D8135

hgext/phabricator.py

@@ -1,1803 +1,1815 b''
 # phabricator.py - simple Phabricator integration
 #
 # Copyright 2017 Facebook, Inc.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 """simple Phabricator integration (EXPERIMENTAL)
 
 This extension provides a ``phabsend`` command which sends a stack of
 changesets to Phabricator, and a ``phabread`` command which prints a stack of
 revisions in a format suitable for :hg:`import`, and a ``phabupdate`` command
 to update statuses in batch.
 
 A "phabstatus" view for :hg:`show` is also provided; it displays status
 information of Phabricator differentials associated with unfinished
 changesets.
 
 By default, Phabricator requires ``Test Plan`` which might prevent some
 changeset from being sent. The requirement could be disabled by changing
 ``differential.require-test-plan-field`` config server side.
 
 Config::
 
     [phabricator]
     # Phabricator URL
     url = https://phab.example.com/
 
     # Repo callsign. If a repo has a URL https://$HOST/diffusion/FOO, then its
     # callsign is "FOO".
     callsign = FOO
 
     # curl command to use. If not set (default), use builtin HTTP library to
     # communicate. If set, use the specified curl command. This could be useful
     # if you need to specify advanced options that is not easily supported by
     # the internal library.
     curlcmd = curl --connect-timeout 2 --retry 3 --silent
 
     [auth]
     example.schemes = https
     example.prefix = phab.example.com
 
     # API token. Get it from https://$HOST/conduit/login/
     example.phabtoken = cli-xxxxxxxxxxxxxxxxxxxxxxxxxxxx
 """
 
 from __future__ import absolute_import
 
 import base64
 import contextlib
 import hashlib
 import itertools
 import json
 import mimetypes
 import operator
 import re
 
 from mercurial.node import bin, nullid
 from mercurial.i18n import _
 from mercurial.pycompat import getattr
 from mercurial.thirdparty import attr
 from mercurial import (
     cmdutil,
     context,
     encoding,
     error,
     exthelper,
     graphmod,
     httpconnection as httpconnectionmod,
     localrepo,
     logcmdutil,
     match,
     mdiff,
     obsutil,
     parser,
     patch,
     phases,
     pycompat,
     scmutil,
     smartset,
     tags,
     templatefilters,
     templateutil,
     url as urlmod,
     util,
 )
 from mercurial.utils import (
     procutil,
     stringutil,
 )
 from . import show
 
 
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
 # be specifying the version(s) of Mercurial they are tested with, or
 # leave the attribute unspecified.
 testedwith = b'ships-with-hg-core'
 
 eh = exthelper.exthelper()
 
 cmdtable = eh.cmdtable
 command = eh.command
 configtable = eh.configtable
 templatekeyword = eh.templatekeyword
 uisetup = eh.finaluisetup
 
 # developer config: phabricator.batchsize
 eh.configitem(
     b'phabricator', b'batchsize', default=12,
 )
 eh.configitem(
     b'phabricator', b'callsign', default=None,
 )
 eh.configitem(
     b'phabricator', b'curlcmd', default=None,
 )
 # developer config: phabricator.repophid
 eh.configitem(
     b'phabricator', b'repophid', default=None,
 )
 eh.configitem(
     b'phabricator', b'url', default=None,
 )
 eh.configitem(
     b'phabsend', b'confirm', default=False,
 )
 
 colortable = {
     b'phabricator.action.created': b'green',
     b'phabricator.action.skipped': b'magenta',
     b'phabricator.action.updated': b'magenta',
     b'phabricator.desc': b'',
     b'phabricator.drev': b'bold',
     b'phabricator.node': b'',
     b'phabricator.status.abandoned': b'magenta dim',
     b'phabricator.status.accepted': b'green bold',
     b'phabricator.status.closed': b'green',
     b'phabricator.status.needsreview': b'yellow',
     b'phabricator.status.needsrevision': b'red',
     b'phabricator.status.changesplanned': b'red',
 }
 
 _VCR_FLAGS = [
     (
         b'',
         b'test-vcr',
         b'',
         _(
             b'Path to a vcr file. If nonexistent, will record a new vcr transcript'
             b', otherwise will mock all http requests using the specified vcr file.'
             b' (ADVANCED)'
         ),
     ),
 ]
 
 
 @eh.wrapfunction(localrepo, "loadhgrc")
 def _loadhgrc(orig, ui, wdirvfs, hgvfs, requirements):
     """Load ``.arcconfig`` content into a ui instance on repository open.
     """
     result = False
     arcconfig = {}
 
     try:
         # json.loads only accepts bytes from 3.6+
         rawparams = encoding.unifromlocal(wdirvfs.read(b".arcconfig"))
         # json.loads only returns unicode strings
         arcconfig = pycompat.rapply(
             lambda x: encoding.unitolocal(x)
             if isinstance(x, pycompat.unicode)
             else x,
             pycompat.json_loads(rawparams),
         )
 
         result = True
     except ValueError:
         ui.warn(_(b"invalid JSON in %s\n") % wdirvfs.join(b".arcconfig"))
     except IOError:
         pass
 
     cfg = util.sortdict()
 
     if b"repository.callsign" in arcconfig:
         cfg[(b"phabricator", b"callsign")] = arcconfig[b"repository.callsign"]
 
     if b"phabricator.uri" in arcconfig:
         cfg[(b"phabricator", b"url")] = arcconfig[b"phabricator.uri"]
 
     if cfg:
         ui.applyconfig(cfg, source=wdirvfs.join(b".arcconfig"))
 
     return orig(ui, wdirvfs, hgvfs, requirements) or result  # Load .hg/hgrc
 
 
 def vcrcommand(name, flags, spec, helpcategory=None, optionalrepo=False):
     fullflags = flags + _VCR_FLAGS
 
     def hgmatcher(r1, r2):
         if r1.uri != r2.uri or r1.method != r2.method:
             return False
         r1params = util.urlreq.parseqs(r1.body)
         r2params = util.urlreq.parseqs(r2.body)
         for key in r1params:
             if key not in r2params:
                 return False
             value = r1params[key][0]
             # we want to compare json payloads without worrying about ordering
             if value.startswith(b'{') and value.endswith(b'}'):
                 r1json = pycompat.json_loads(value)
                 r2json = pycompat.json_loads(r2params[key][0])
                 if r1json != r2json:
                     return False
             elif r2params[key][0] != value:
                 return False
         return True
 
     def sanitiserequest(request):
         request.body = re.sub(
             br'cli-[a-z0-9]+', br'cli-hahayouwish', request.body
         )
         return request
 
     def sanitiseresponse(response):
         if 'set-cookie' in response['headers']:
             del response['headers']['set-cookie']
         return response
 
     def decorate(fn):
         def inner(*args, **kwargs):
             cassette = pycompat.fsdecode(kwargs.pop('test_vcr', None))
             if cassette:
                 import hgdemandimport
 
                 with hgdemandimport.deactivated():
                     import vcr as vcrmod
                     import vcr.stubs as stubs
 
                     vcr = vcrmod.VCR(
                         serializer='json',
                         before_record_request=sanitiserequest,
                         before_record_response=sanitiseresponse,
                         custom_patches=[
                             (
                                 urlmod,
                                 'httpconnection',
                                 stubs.VCRHTTPConnection,
                             ),
                             (
                                 urlmod,
                                 'httpsconnection',
                                 stubs.VCRHTTPSConnection,
                             ),
                         ],
                     )
                     vcr.register_matcher('hgmatcher', hgmatcher)
                     with vcr.use_cassette(cassette, match_on=['hgmatcher']):
                         return fn(*args, **kwargs)
             return fn(*args, **kwargs)
 
         inner.__name__ = fn.__name__
         inner.__doc__ = fn.__doc__
         return command(
             name,
             fullflags,
             spec,
             helpcategory=helpcategory,
             optionalrepo=optionalrepo,
         )(inner)
 
     return decorate
 
 
 def urlencodenested(params):
     """like urlencode, but works with nested parameters.
 
     For example, if params is {'a': ['b', 'c'], 'd': {'e': 'f'}}, it will be
     flattened to {'a[0]': 'b', 'a[1]': 'c', 'd[e]': 'f'} and then passed to
     urlencode. Note: the encoding is consistent with PHP's http_build_query.
     """
     flatparams = util.sortdict()
 
     def process(prefix, obj):
         if isinstance(obj, bool):
             obj = {True: b'true', False: b'false'}[obj]  # Python -> PHP form
         lister = lambda l: [(b'%d' % k, v) for k, v in enumerate(l)]
         items = {list: lister, dict: lambda x: x.items()}.get(type(obj))
         if items is None:
             flatparams[prefix] = obj
         else:
             for k, v in items(obj):
                 if prefix:
                     process(b'%s[%s]' % (prefix, k), v)
                 else:
                     process(k, v)
 
     process(b'', params)
     return util.urlreq.urlencode(flatparams)
 
 
 def readurltoken(ui):
     """return conduit url, token and make sure they exist
 
     Currently read from [auth] config section. In the future, it might
     make sense to read from .arcconfig and .arcrc as well.
     """
     url = ui.config(b'phabricator', b'url')
     if not url:
         raise error.Abort(
             _(b'config %s.%s is required') % (b'phabricator', b'url')
         )
 
     res = httpconnectionmod.readauthforuri(ui, url, util.url(url).user)
     token = None
 
     if res:
         group, auth = res
 
         ui.debug(b"using auth.%s.* for authentication\n" % group)
 
         token = auth.get(b'phabtoken')
 
     if not token:
         raise error.Abort(
             _(b'Can\'t find conduit token associated to %s') % (url,)
         )
 
     return url, token
 
 
 def callconduit(ui, name, params):
     """call Conduit API, params is a dict. return json.loads result, or None"""
     host, token = readurltoken(ui)
     url, authinfo = util.url(b'/'.join([host, b'api', name])).authinfo()
     ui.debug(b'Conduit Call: %s %s\n' % (url, pycompat.byterepr(params)))
     params = params.copy()
     params[b'__conduit__'] = {
         b'token': token,
     }
     rawdata = {
         b'params': templatefilters.json(params),
         b'output': b'json',
         b'__conduit__': 1,
     }
     data = urlencodenested(rawdata)
     curlcmd = ui.config(b'phabricator', b'curlcmd')
     if curlcmd:
         sin, sout = procutil.popen2(
             b'%s -d @- %s' % (curlcmd, procutil.shellquote(url))
         )
         sin.write(data)
         sin.close()
         body = sout.read()
     else:
         urlopener = urlmod.opener(ui, authinfo)
         request = util.urlreq.request(pycompat.strurl(url), data=data)
         with contextlib.closing(urlopener.open(request)) as rsp:
             body = rsp.read()
     ui.debug(b'Conduit Response: %s\n' % body)
     parsed = pycompat.rapply(
         lambda x: encoding.unitolocal(x)
         if isinstance(x, pycompat.unicode)
         else x,
         # json.loads only accepts bytes from py3.6+
         pycompat.json_loads(encoding.unifromlocal(body)),
     )
     if parsed.get(b'error_code'):
         msg = _(b'Conduit Error (%s): %s') % (
             parsed[b'error_code'],
             parsed[b'error_info'],
         )
         raise error.Abort(msg)
     return parsed[b'result']
 
 
 @vcrcommand(b'debugcallconduit', [], _(b'METHOD'), optionalrepo=True)
 def debugcallconduit(ui, repo, name):
     """call Conduit API
 
     Call parameters are read from stdin as a JSON blob. Result will be written
     to stdout as a JSON blob.
     """
     # json.loads only accepts bytes from 3.6+
     rawparams = encoding.unifromlocal(ui.fin.read())
     # json.loads only returns unicode strings
     params = pycompat.rapply(
         lambda x: encoding.unitolocal(x)
         if isinstance(x, pycompat.unicode)
         else x,
         pycompat.json_loads(rawparams),
     )
     # json.dumps only accepts unicode strings
     result = pycompat.rapply(
         lambda x: encoding.unifromlocal(x) if isinstance(x, bytes) else x,
         callconduit(ui, name, params),
     )
     s = json.dumps(result, sort_keys=True, indent=2, separators=(u',', u': '))
     ui.write(b'%s\n' % encoding.unitolocal(s))
 
 
 def getrepophid(repo):
     """given callsign, return repository PHID or None"""
     # developer config: phabricator.repophid
     repophid = repo.ui.config(b'phabricator', b'repophid')
     if repophid:
         return repophid
     callsign = repo.ui.config(b'phabricator', b'callsign')
     if not callsign:
         return None
     query = callconduit(
         repo.ui,
         b'diffusion.repository.search',
         {b'constraints': {b'callsigns': [callsign]}},
     )
     if len(query[b'data']) == 0:
         return None
     repophid = query[b'data'][0][b'phid']
     repo.ui.setconfig(b'phabricator', b'repophid', repophid)
     return repophid
 
 
 _differentialrevisiontagre = re.compile(br'\AD([1-9][0-9]*)\Z')
 _differentialrevisiondescre = re.compile(
     br'^Differential Revision:\s*(?P<url>(?:.*)D(?P<id>[1-9][0-9]*))$', re.M
 )
 
 
 def getoldnodedrevmap(repo, nodelist):
     """find previous nodes that has been sent to Phabricator
 
     return {node: (oldnode, Differential diff, Differential Revision ID)}
     for node in nodelist with known previous sent versions, or associated
     Differential Revision IDs. ``oldnode`` and ``Differential diff`` could
     be ``None``.
 
     Examines commit messages like "Differential Revision:" to get the
     association information.
 
     If such commit message line is not found, examines all precursors and their
     tags. Tags with format like "D1234" are considered a match and the node
     with that tag, and the number after "D" (ex. 1234) will be returned.
 
     The ``old node``, if not None, is guaranteed to be the last diff of
     corresponding Differential Revision, and exist in the repo.
     """
     unfi = repo.unfiltered()
     has_node = unfi.changelog.index.has_node
 
     result = {}  # {node: (oldnode?, lastdiff?, drev)}
     toconfirm = {}  # {node: (force, {precnode}, drev)}
     for node in nodelist:
         ctx = unfi[node]
         # For tags like "D123", put them into "toconfirm" to verify later
         precnodes = list(obsutil.allpredecessors(unfi.obsstore, [node]))
         for n in precnodes:
             if has_node(n):
                 for tag in unfi.nodetags(n):
                     m = _differentialrevisiontagre.match(tag)
                     if m:
                         toconfirm[node] = (0, set(precnodes), int(m.group(1)))
                         break
                 else:
                     continue  # move to next predecessor
                 break  # found a tag, stop
         else:
             # Check commit message
             m = _differentialrevisiondescre.search(ctx.description())
             if m:
                 toconfirm[node] = (1, set(precnodes), int(m.group('id')))
 
     # Double check if tags are genuine by collecting all old nodes from
     # Phabricator, and expect precursors overlap with it.
     if toconfirm:
         drevs = [drev for force, precs, drev in toconfirm.values()]
         alldiffs = callconduit(
             unfi.ui, b'differential.querydiffs', {b'revisionIDs': drevs}
         )
         getnode = lambda d: bin(getdiffmeta(d).get(b'node', b'')) or None
         for newnode, (force, precset, drev) in toconfirm.items():
             diffs = [
                 d for d in alldiffs.values() if int(d[b'revisionID']) == drev
             ]
 
             # "precursors" as known by Phabricator
             phprecset = set(getnode(d) for d in diffs)
 
             # Ignore if precursors (Phabricator and local repo) do not overlap,
             # and force is not set (when commit message says nothing)
             if not force and not bool(phprecset & precset):
                 tagname = b'D%d' % drev
                 tags.tag(
                     repo,
                     tagname,
                     nullid,
                     message=None,
                     user=None,
                     date=None,
                     local=True,
                 )
                 unfi.ui.warn(
                     _(
                         b'D%d: local tag removed - does not match '
                         b'Differential history\n'
                     )
                     % drev
                 )
                 continue
 
             # Find the last node using Phabricator metadata, and make sure it
             # exists in the repo
             oldnode = lastdiff = None
             if diffs:
                 lastdiff = max(diffs, key=lambda d: int(d[b'id']))
                 oldnode = getnode(lastdiff)
                 if oldnode and not has_node(oldnode):
                     oldnode = None
 
             result[newnode] = (oldnode, lastdiff, drev)
 
     return result
 
 
 def getdrevmap(repo, revs):
     """Return a dict mapping each rev in `revs` to their Differential Revision
     ID or None.
     """
     result = {}
     for rev in revs:
         result[rev] = None
         ctx = repo[rev]
         # Check commit message
         m = _differentialrevisiondescre.search(ctx.description())
         if m:
             result[rev] = int(m.group('id'))
             continue
         # Check tags
         for tag in repo.nodetags(ctx.node()):
             m = _differentialrevisiontagre.match(tag)
             if m:
                 result[rev] = int(m.group(1))
                 break
 
     return result
 
 
 def getdiff(ctx, diffopts):
     """plain-text diff without header (user, commit message, etc)"""
     output = util.stringio()
     for chunk, _label in patch.diffui(
         ctx.repo(), ctx.p1().node(), ctx.node(), None, opts=diffopts
     ):
         output.write(chunk)
     return output.getvalue()
 
 
 class DiffChangeType(object):
     ADD = 1
     CHANGE = 2
     DELETE = 3
     MOVE_AWAY = 4
     COPY_AWAY = 5
     MOVE_HERE = 6
     COPY_HERE = 7
     MULTICOPY = 8
 
 
 class DiffFileType(object):
     TEXT = 1
     IMAGE = 2
     BINARY = 3
 
 
 @attr.s
 class phabhunk(dict):
     """Represents a Differential hunk, which is owned by a Differential change
     """
 
     oldOffset = attr.ib(default=0)  # camelcase-required
     oldLength = attr.ib(default=0)  # camelcase-required
     newOffset = attr.ib(default=0)  # camelcase-required
     newLength = attr.ib(default=0)  # camelcase-required
     corpus = attr.ib(default='')
     # These get added to the phabchange's equivalents
     addLines = attr.ib(default=0)  # camelcase-required
     delLines = attr.ib(default=0)  # camelcase-required
 
 
 @attr.s
 class phabchange(object):
     """Represents a Differential change, owns Differential hunks and owned by a
     Differential diff.  Each one represents one file in a diff.
     """
 
     currentPath = attr.ib(default=None)  # camelcase-required
     oldPath = attr.ib(default=None)  # camelcase-required
     awayPaths = attr.ib(default=attr.Factory(list))  # camelcase-required
     metadata = attr.ib(default=attr.Factory(dict))
     oldProperties = attr.ib(default=attr.Factory(dict))  # camelcase-required
     newProperties = attr.ib(default=attr.Factory(dict))  # camelcase-required
     type = attr.ib(default=DiffChangeType.CHANGE)
     fileType = attr.ib(default=DiffFileType.TEXT)  # camelcase-required
     commitHash = attr.ib(default=None)  # camelcase-required
     addLines = attr.ib(default=0)  # camelcase-required
     delLines = attr.ib(default=0)  # camelcase-required
     hunks = attr.ib(default=attr.Factory(list))
 
     def copynewmetadatatoold(self):
         for key in list(self.metadata.keys()):
             newkey = key.replace(b'new:', b'old:')
             self.metadata[newkey] = self.metadata[key]
 
     def addoldmode(self, value):
         self.oldProperties[b'unix:filemode'] = value
 
     def addnewmode(self, value):
         self.newProperties[b'unix:filemode'] = value
 
     def addhunk(self, hunk):
         if not isinstance(hunk, phabhunk):
             raise error.Abort(b'phabchange.addhunk only takes phabhunks')
         self.hunks.append(pycompat.byteskwargs(attr.asdict(hunk)))
         # It's useful to include these stats since the Phab web UI shows them,
         # and uses them to estimate how large a change a Revision is. Also used
         # in email subjects for the [+++--] bit.
         self.addLines += hunk.addLines
         self.delLines += hunk.delLines
 
 
 @attr.s
 class phabdiff(object):
     """Represents a Differential diff, owns Differential changes.  Corresponds
     to a commit.
     """
 
     # Doesn't seem to be any reason to send this (output of uname -n)
     sourceMachine = attr.ib(default=b'')  # camelcase-required
     sourcePath = attr.ib(default=b'/')  # camelcase-required
     sourceControlBaseRevision = attr.ib(default=b'0' * 40)  # camelcase-required
     sourceControlPath = attr.ib(default=b'/')  # camelcase-required
     sourceControlSystem = attr.ib(default=b'hg')  # camelcase-required
     branch = attr.ib(default=b'default')
     bookmark = attr.ib(default=None)
     creationMethod = attr.ib(default=b'phabsend')  # camelcase-required
     lintStatus = attr.ib(default=b'none')  # camelcase-required
     unitStatus = attr.ib(default=b'none')  # camelcase-required
     changes = attr.ib(default=attr.Factory(dict))
     repositoryPHID = attr.ib(default=None)  # camelcase-required
 
     def addchange(self, change):
         if not isinstance(change, phabchange):
             raise error.Abort(b'phabdiff.addchange only takes phabchanges')
         self.changes[change.currentPath] = pycompat.byteskwargs(
             attr.asdict(change)
         )
 
 
 def maketext(pchange, ctx, fname):
     """populate the phabchange for a text file"""
     repo = ctx.repo()
     fmatcher = match.exact([fname])
     diffopts = mdiff.diffopts(git=True, context=32767)
     _pfctx, _fctx, header, fhunks = next(
         patch.diffhunks(repo, ctx.p1(), ctx, fmatcher, opts=diffopts)
     )
 
     for fhunk in fhunks:
         (oldOffset, oldLength, newOffset, newLength), lines = fhunk
         corpus = b''.join(lines[1:])
         shunk = list(header)
         shunk.extend(lines)
         _mf, _mt, addLines, delLines, _hb = patch.diffstatsum(
             patch.diffstatdata(util.iterlines(shunk))
         )
         pchange.addhunk(
             phabhunk(
                 oldOffset,
                 oldLength,
                 newOffset,
                 newLength,
                 corpus,
                 addLines,
                 delLines,
             )
         )
 
 
 def uploadchunks(fctx, fphid):
     """upload large binary files as separate chunks.
     Phab requests chunking over 8MiB, and splits into 4MiB chunks
     """
     ui = fctx.repo().ui
     chunks = callconduit(ui, b'file.querychunks', {b'filePHID': fphid})
     with ui.makeprogress(
         _(b'uploading file chunks'), unit=_(b'chunks'), total=len(chunks)
     ) as progress:
         for chunk in chunks:
             progress.increment()
             if chunk[b'complete']:
                 continue
             bstart = int(chunk[b'byteStart'])
             bend = int(chunk[b'byteEnd'])
             callconduit(
                 ui,
                 b'file.uploadchunk',
                 {
                     b'filePHID': fphid,
                     b'byteStart': bstart,
                     b'data': base64.b64encode(fctx.data()[bstart:bend]),
                     b'dataEncoding': b'base64',
                 },
             )
 
 
 def uploadfile(fctx):
     """upload binary files to Phabricator"""
     repo = fctx.repo()
     ui = repo.ui
     fname = fctx.path()
     size = fctx.size()
     fhash = pycompat.bytestr(hashlib.sha256(fctx.data()).hexdigest())
 
     # an allocate call is required first to see if an upload is even required
     # (Phab might already have it) and to determine if chunking is needed
     allocateparams = {
         b'name': fname,
         b'contentLength': size,
         b'contentHash': fhash,
     }
     filealloc = callconduit(ui, b'file.allocate', allocateparams)
     fphid = filealloc[b'filePHID']
 
     if filealloc[b'upload']:
         ui.write(_(b'uploading %s\n') % bytes(fctx))
         if not fphid:
             uploadparams = {
                 b'name': fname,
                 b'data_base64': base64.b64encode(fctx.data()),
             }
             fphid = callconduit(ui, b'file.upload', uploadparams)
         else:
             uploadchunks(fctx, fphid)
     else:
         ui.debug(b'server already has %s\n' % bytes(fctx))
 
     if not fphid:
         raise error.Abort(b'Upload of %s failed.' % bytes(fctx))
 
     return fphid
 
 
 def addoldbinary(pchange, fctx):
     """add the metadata for the previous version of a binary file to the
     phabchange for the new version
     """
     oldfctx = fctx.p1()
     if fctx.cmp(oldfctx):
         # Files differ, add the old one
         pchange.metadata[b'old:file:size'] = oldfctx.size()
         mimeguess, _enc = mimetypes.guess_type(
             encoding.unifromlocal(oldfctx.path())
         )
         if mimeguess:
             pchange.metadata[b'old:file:mime-type'] = pycompat.bytestr(
                 mimeguess
             )
         fphid = uploadfile(oldfctx)
         pchange.metadata[b'old:binary-phid'] = fphid
     else:
         # If it's left as IMAGE/BINARY web UI might try to display it
         pchange.fileType = DiffFileType.TEXT
         pchange.copynewmetadatatoold()
 
 
 def makebinary(pchange, fctx):
     """populate the phabchange for a binary file"""
     pchange.fileType = DiffFileType.BINARY
     fphid = uploadfile(fctx)
     pchange.metadata[b'new:binary-phid'] = fphid
     pchange.metadata[b'new:file:size'] = fctx.size()
     mimeguess, _enc = mimetypes.guess_type(encoding.unifromlocal(fctx.path()))
     if mimeguess:
         mimeguess = pycompat.bytestr(mimeguess)
         pchange.metadata[b'new:file:mime-type'] = mimeguess
         if mimeguess.startswith(b'image/'):
             pchange.fileType = DiffFileType.IMAGE
 
 
 # Copied from mercurial/patch.py
 gitmode = {b'l': b'120000', b'x': b'100755', b'': b'100644'}
 
 
 def notutf8(fctx):
     """detect non-UTF-8 text files since Phabricator requires them to be marked
     as binary
     """
     try:
         fctx.data().decode('utf-8')
         if fctx.parents():
             fctx.p1().data().decode('utf-8')
         return False
     except UnicodeDecodeError:
         fctx.repo().ui.write(
             _(b'file %s detected as non-UTF-8, marked as binary\n')
             % fctx.path()
         )
         return True
 
 
 def addremoved(pdiff, ctx, removed):
     """add removed files to the phabdiff. Shouldn't include moves"""
     for fname in removed:
         pchange = phabchange(
             currentPath=fname, oldPath=fname, type=DiffChangeType.DELETE
         )
         pchange.addoldmode(gitmode[ctx.p1()[fname].flags()])
         fctx = ctx.p1()[fname]
         if not (fctx.isbinary() or notutf8(fctx)):
             maketext(pchange, ctx, fname)
 
         pdiff.addchange(pchange)
 
 
 def addmodified(pdiff, ctx, modified):
     """add modified files to the phabdiff"""
     for fname in modified:
         fctx = ctx[fname]
         pchange = phabchange(currentPath=fname, oldPath=fname)
         filemode = gitmode[ctx[fname].flags()]
         originalmode = gitmode[ctx.p1()[fname].flags()]
         if filemode != originalmode:
             pchange.addoldmode(originalmode)
             pchange.addnewmode(filemode)
 
         if fctx.isbinary() or notutf8(fctx):
             makebinary(pchange, fctx)
             addoldbinary(pchange, fctx)
         else:
             maketext(pchange, ctx, fname)
 
         pdiff.addchange(pchange)
 
 
 def addadded(pdiff, ctx, added, removed):
     """add file adds to the phabdiff, both new files and copies/moves"""
     # Keep track of files that've been recorded as moved/copied, so if there are
     # additional copies we can mark them (moves get removed from removed)
     copiedchanges = {}
     movedchanges = {}
     for fname in added:
         fctx = ctx[fname]
         pchange = phabchange(currentPath=fname)
 
         filemode = gitmode[ctx[fname].flags()]
         renamed = fctx.renamed()
 
         if renamed:
             originalfname = renamed[0]
             originalmode = gitmode[ctx.p1()[originalfname].flags()]
             pchange.oldPath = originalfname
 
             if originalfname in removed:
                 origpchange = phabchange(
                     currentPath=originalfname,
                     oldPath=originalfname,
                     type=DiffChangeType.MOVE_AWAY,
                     awayPaths=[fname],
                 )
                 movedchanges[originalfname] = origpchange
                 removed.remove(originalfname)
                 pchange.type = DiffChangeType.MOVE_HERE
             elif originalfname in movedchanges:
                 movedchanges[originalfname].type = DiffChangeType.MULTICOPY
                 movedchanges[originalfname].awayPaths.append(fname)
                 pchange.type = DiffChangeType.COPY_HERE
             else:  # pure copy
                 if originalfname not in copiedchanges:
                     origpchange = phabchange(
                         currentPath=originalfname, type=DiffChangeType.COPY_AWAY
                     )
                     copiedchanges[originalfname] = origpchange
                 else:
                     origpchange = copiedchanges[originalfname]
                 origpchange.awayPaths.append(fname)
                 pchange.type = DiffChangeType.COPY_HERE
 
             if filemode != originalmode:
                 pchange.addoldmode(originalmode)
                 pchange.addnewmode(filemode)
         else:  # Brand-new file
             pchange.addnewmode(gitmode[fctx.flags()])
             pchange.type = DiffChangeType.ADD
 
         if fctx.isbinary() or notutf8(fctx):
             makebinary(pchange, fctx)
             if renamed:
                 addoldbinary(pchange, fctx)
         else:
             maketext(pchange, ctx, fname)
 
         pdiff.addchange(pchange)
 
     for _path, copiedchange in copiedchanges.items():
         pdiff.addchange(copiedchange)
     for _path, movedchange in movedchanges.items():
         pdiff.addchange(movedchange)
 
 
 def creatediff(ctx):
     """create a Differential Diff"""
     repo = ctx.repo()
     repophid = getrepophid(repo)
     # Create a "Differential Diff" via "differential.creatediff" API
     pdiff = phabdiff(
         sourceControlBaseRevision=b'%s' % ctx.p1().hex(),
         branch=b'%s' % ctx.branch(),
     )
     modified, added, removed, _d, _u, _i, _c = ctx.p1().status(ctx)
     # addadded will remove moved files from removed, so addremoved won't get
     # them
     addadded(pdiff, ctx, added, removed)
     addmodified(pdiff, ctx, modified)
     addremoved(pdiff, ctx, removed)
     if repophid:
         pdiff.repositoryPHID = repophid
     diff = callconduit(
         repo.ui,
         b'differential.creatediff',
         pycompat.byteskwargs(attr.asdict(pdiff)),
     )
     if not diff:
         raise error.Abort(_(b'cannot create diff for %s') % ctx)
     return diff
 
 
 def writediffproperties(ctx, diff):
     """write metadata to diff so patches could be applied losslessly"""
     # creatediff returns with a diffid but query returns with an id
     diffid = diff.get(b'diffid', diff.get(b'id'))
     params = {
         b'diff_id': diffid,
         b'name': b'hg:meta',
         b'data': templatefilters.json(
             {
                 b'user': ctx.user(),
                 b'date': b'%d %d' % ctx.date(),
                 b'branch': ctx.branch(),
                 b'node': ctx.hex(),
                 b'parent': ctx.p1().hex(),
             }
         ),
     }
     callconduit(ctx.repo().ui, b'differential.setdiffproperty', params)
 
     params = {
         b'diff_id': diffid,
         b'name': b'local:commits',
         b'data': templatefilters.json(
             {
                 ctx.hex(): {
                     b'author': stringutil.person(ctx.user()),
                     b'authorEmail': stringutil.email(ctx.user()),
                     b'time': int(ctx.date()[0]),
                     b'commit': ctx.hex(),
                     b'parents': [ctx.p1().hex()],
                     b'branch': ctx.branch(),
                 },
             }
         ),
     }
     callconduit(ctx.repo().ui, b'differential.setdiffproperty', params)
 
 
 def createdifferentialrevision(
     ctx,
     revid=None,
     parentrevphid=None,
     oldnode=None,
     olddiff=None,
     actions=None,
     comment=None,
 ):
     """create or update a Differential Revision
 
     If revid is None, create a new Differential Revision, otherwise update
     revid. If parentrevphid is not None, set it as a dependency.
 
     If oldnode is not None, check if the patch content (without commit message
     and metadata) has changed before creating another diff.
 
     If actions is not None, they will be appended to the transaction.
     """
     repo = ctx.repo()
     if oldnode:
         diffopts = mdiff.diffopts(git=True, context=32767)
         oldctx = repo.unfiltered()[oldnode]
         neednewdiff = getdiff(ctx, diffopts) != getdiff(oldctx, diffopts)
     else:
         neednewdiff = True
 
     transactions = []
     if neednewdiff:
         diff = creatediff(ctx)
         transactions.append({b'type': b'update', b'value': diff[b'phid']})
         if comment:
             transactions.append({b'type': b'comment', b'value': comment})
     else:
         # Even if we don't need to upload a new diff because the patch content
         # does not change. We might still need to update its metadata so
         # pushers could know the correct node metadata.
         assert olddiff
         diff = olddiff
     writediffproperties(ctx, diff)
 
     # Set the parent Revision every time, so commit re-ordering is picked-up
     if parentrevphid:
         transactions.append(
             {b'type': b'parents.set', b'value': [parentrevphid]}
         )
 
     if actions:
         transactions += actions
 
     # Parse commit message and update related fields.
     desc = ctx.description()
     info = callconduit(
         repo.ui, b'differential.parsecommitmessage', {b'corpus': desc}
     )
     for k, v in info[b'fields'].items():
         if k in [b'title', b'summary', b'testPlan']:
             transactions.append({b'type': k, b'value': v})
 
     params = {b'transactions': transactions}
     if revid is not None:
         # Update an existing Differential Revision
         params[b'objectIdentifier'] = revid
 
     revision = callconduit(repo.ui, b'differential.revision.edit', params)
     if not revision:
         raise error.Abort(_(b'cannot create revision for %s') % ctx)
 
     return revision, diff
 
 
 def userphids(ui, names):
     """convert user names to PHIDs"""
     names = [name.lower() for name in names]
     query = {b'constraints': {b'usernames': names}}
     result = callconduit(ui, b'user.search', query)
     # username not found is not an error of the API. So check if we have missed
     # some names here.
     data = result[b'data']
     resolved = set(entry[b'fields'][b'username'].lower() for entry in data)
     unresolved = set(names) - resolved
     if unresolved:
         raise error.Abort(
             _(b'unknown username: %s') % b' '.join(sorted(unresolved))
         )
     return [entry[b'phid'] for entry in data]
 
 
 @vcrcommand(
     b'phabsend',
     [
         (b'r', b'rev', [], _(b'revisions to send'), _(b'REV')),
         (b'', b'amend', True, _(b'update commit messages')),
         (b'', b'reviewer', [], _(b'specify reviewers')),
         (b'', b'blocker', [], _(b'specify blocking reviewers')),
         (
             b'm',
             b'comment',
             b'',
             _(b'add a comment to Revisions with new/updated Diffs'),
         ),
         (b'', b'confirm', None, _(b'ask for confirmation before sending')),
     ],
     _(b'REV [OPTIONS]'),
     helpcategory=command.CATEGORY_IMPORT_EXPORT,
 )
 def phabsend(ui, repo, *revs, **opts):
     """upload changesets to Phabricator
 
     If there are multiple revisions specified, they will be send as a stack
     with a linear dependencies relationship using the order specified by the
     revset.
 
     For the first time uploading changesets, local tags will be created to
     maintain the association. After the first time, phabsend will check
     obsstore and tags information so it can figure out whether to update an
     existing Differential Revision, or create a new one.
 
     If --amend is set, update commit messages so they have the
     ``Differential Revision`` URL, remove related tags. This is similar to what
     arcanist will do, and is more desired in author-push workflows. Otherwise,
     use local tags to record the ``Differential Revision`` association.
 
     The --confirm option lets you confirm changesets before sending them. You
     can also add following to your configuration file to make it default
     behaviour::
 
         [phabsend]
         confirm = true
 
     phabsend will check obsstore and the above association to decide whether to
     update an existing Differential Revision, or create a new one.
     """
     opts = pycompat.byteskwargs(opts)
     revs = list(revs) + opts.get(b'rev', [])
     revs = scmutil.revrange(repo, revs)
     revs.sort()  # ascending order to preserve topological parent/child in phab
 
     if not revs:
         raise error.Abort(_(b'phabsend requires at least one changeset'))
     if opts.get(b'amend'):
         cmdutil.checkunfinished(repo)
 
     # {newnode: (oldnode, olddiff, olddrev}
     oldmap = getoldnodedrevmap(repo, [repo[r].node() for r in revs])
 
     confirm = ui.configbool(b'phabsend', b'confirm')
     confirm |= bool(opts.get(b'confirm'))
     if confirm:
         confirmed = _confirmbeforesend(repo, revs, oldmap)
         if not confirmed:
             raise error.Abort(_(b'phabsend cancelled'))
 
     actions = []
     reviewers = opts.get(b'reviewer', [])
     blockers = opts.get(b'blocker', [])
     phids = []
     if reviewers:
         phids.extend(userphids(repo.ui, reviewers))
     if blockers:
         phids.extend(
             map(
                 lambda phid: b'blocking(%s)' % phid,
                 userphids(repo.ui, blockers),
             )
         )
     if phids:
         actions.append({b'type': b'reviewers.add', b'value': phids})
 
     drevids = []  # [int]
     diffmap = {}  # {newnode: diff}
 
     # Send patches one by one so we know their Differential Revision PHIDs and
     # can provide dependency relationship
     lastrevphid = None
     for rev in revs:
         ui.debug(b'sending rev %d\n' % rev)
         ctx = repo[rev]
 
         # Get Differential Revision ID
         oldnode, olddiff, revid = oldmap.get(ctx.node(), (None, None, None))
         if oldnode != ctx.node() or opts.get(b'amend'):
             # Create or update Differential Revision
             revision, diff = createdifferentialrevision(
                 ctx,
                 revid,
                 lastrevphid,
                 oldnode,
                 olddiff,
                 actions,
                 opts.get(b'comment'),
             )
             diffmap[ctx.node()] = diff
             newrevid = int(revision[b'object'][b'id'])
             newrevphid = revision[b'object'][b'phid']
             if revid:
                 action = b'updated'
             else:
                 action = b'created'
 
             # Create a local tag to note the association, if commit message
             # does not have it already
             m = _differentialrevisiondescre.search(ctx.description())
             if not m or int(m.group('id')) != newrevid:
                 tagname = b'D%d' % newrevid
                 tags.tag(
                     repo,
                     tagname,
                     ctx.node(),
                     message=None,
                     user=None,
                     date=None,
                     local=True,
                 )
         else:
             # Nothing changed. But still set "newrevphid" so the next revision
             # could depend on this one and "newrevid" for the summary line.
             newrevphid = querydrev(repo.ui, b'%d' % revid)[0][b'phid']
             newrevid = revid
             action = b'skipped'
 
         actiondesc = ui.label(
             {
                 b'created': _(b'created'),
                 b'skipped': _(b'skipped'),
                 b'updated': _(b'updated'),
             }[action],
             b'phabricator.action.%s' % action,
         )
         drevdesc = ui.label(b'D%d' % newrevid, b'phabricator.drev')
         nodedesc = ui.label(bytes(ctx), b'phabricator.node')
         desc = ui.label(ctx.description().split(b'\n')[0], b'phabricator.desc')
         ui.write(
             _(b'%s - %s - %s: %s\n') % (drevdesc, actiondesc, nodedesc, desc)
         )
         drevids.append(newrevid)
         lastrevphid = newrevphid
 
     # Update commit messages and remove tags
     if opts.get(b'amend'):
         unfi = repo.unfiltered()
         drevs = callconduit(ui, b'differential.query', {b'ids': drevids})
         with repo.wlock(), repo.lock(), repo.transaction(b'phabsend'):
             wnode = unfi[b'.'].node()
             mapping = {}  # {oldnode: [newnode]}
             for i, rev in enumerate(revs):
                 old = unfi[rev]
                 drevid = drevids[i]
                 drev = [d for d in drevs if int(d[b'id']) == drevid][0]
                 newdesc = getdescfromdrev(drev)
                 # Make sure commit message contain "Differential Revision"
                 if old.description() != newdesc:
                     if old.phase() == phases.public:
                         ui.warn(
                             _(b"warning: not updating public commit %s\n")
                             % scmutil.formatchangeid(old)
                         )
                         continue
                     parents = [
                         mapping.get(old.p1().node(), (old.p1(),))[0],
                         mapping.get(old.p2().node(), (old.p2(),))[0],
                     ]
                     new = context.metadataonlyctx(
                         repo,
                         old,
                         parents=parents,
                         text=newdesc,
                         user=old.user(),
                         date=old.date(),
                         extra=old.extra(),
                     )
 
                     newnode = new.commit()
 
                     mapping[old.node()] = [newnode]
                     # Update diff property
                     # If it fails just warn and keep going, otherwise the DREV
                     # associations will be lost
                     try:
                         writediffproperties(unfi[newnode], diffmap[old.node()])
                     except util.urlerr.urlerror:
                         ui.warnnoi18n(
                             b'Failed to update metadata for D%d\n' % drevid
                         )
                 # Remove local tags since it's no longer necessary
                 tagname = b'D%d' % drevid
                 if tagname in repo.tags():
                     tags.tag(
                         repo,
                         tagname,
                         nullid,
                         message=None,
                         user=None,
                         date=None,
                         local=True,
                     )
             scmutil.cleanupnodes(repo, mapping, b'phabsend', fixphase=True)
             if wnode in mapping:
                 unfi.setparents(mapping[wnode][0])
 
 
 # Map from "hg:meta" keys to header understood by "hg import". The order is
 # consistent with "hg export" output.
 _metanamemap = util.sortdict(
     [
         (b'user', b'User'),
         (b'date', b'Date'),
         (b'branch', b'Branch'),
         (b'node', b'Node ID'),
         (b'parent', b'Parent '),
     ]
 )
 
 
 def _confirmbeforesend(repo, revs, oldmap):
     url, token = readurltoken(repo.ui)
     ui = repo.ui
     for rev in revs:
         ctx = repo[rev]
         desc = ctx.description().splitlines()[0]
         oldnode, olddiff, drevid = oldmap.get(ctx.node(), (None, None, None))
         if drevid:
             drevdesc = ui.label(b'D%d' % drevid, b'phabricator.drev')
         else:
             drevdesc = ui.label(_(b'NEW'), b'phabricator.drev')
 
         ui.write(
             _(b'%s - %s: %s\n')
             % (
                 drevdesc,
                 ui.label(bytes(ctx), b'phabricator.node'),
                 ui.label(desc, b'phabricator.desc'),
             )
         )
 
     if ui.promptchoice(
         _(b'Send the above changes to %s (yn)?$$ &Yes $$ &No') % url
     ):
         return False
 
     return True
 
 
 _knownstatusnames = {
     b'accepted',
     b'needsreview',
     b'needsrevision',
     b'closed',
     b'abandoned',
     b'changesplanned',
 }
 
 
 def _getstatusname(drev):
     """get normalized status name from a Differential Revision"""
     return drev[b'statusName'].replace(b' ', b'').lower()
 
 
 # Small language to specify differential revisions. Support symbols: (), :X,
 # +, and -.
 
 _elements = {
     # token-type: binding-strength, primary, prefix, infix, suffix
     b'(': (12, None, (b'group', 1, b')'), None, None),
     b':': (8, None, (b'ancestors', 8), None, None),
     b'&': (5, None, None, (b'and_', 5), None),
     b'+': (4, None, None, (b'add', 4), None),
     b'-': (4, None, None, (b'sub', 4), None),
     b')': (0, None, None, None, None),
     b'symbol': (0, b'symbol', None, None, None),
     b'end': (0, None, None, None, None),
 }
 
 
 def _tokenize(text):
     view = memoryview(text)  # zero-copy slice
     special = b'():+-& '
     pos = 0
     length = len(text)
     while pos < length:
         symbol = b''.join(
             itertools.takewhile(
                 lambda ch: ch not in special, pycompat.iterbytestr(view[pos:])
             )
         )
         if symbol:
             yield (b'symbol', symbol, pos)
             pos += len(symbol)
         else:  # special char, ignore space
             if text[pos : pos + 1] != b' ':
                 yield (text[pos : pos + 1], None, pos)
             pos += 1
     yield (b'end', None, pos)
 
 
 def _parse(text):
     tree, pos = parser.parser(_elements).parse(_tokenize(text))
     if pos != len(text):
         raise error.ParseError(b'invalid token', pos)
     return tree
 
 
 def _parsedrev(symbol):
     """str -> int or None, ex. 'D45' -> 45; '12' -> 12; 'x' -> None"""
     if symbol.startswith(b'D') and symbol[1:].isdigit():
         return int(symbol[1:])
     if symbol.isdigit():
         return int(symbol)
 
 
 def _prefetchdrevs(tree):
     """return ({single-drev-id}, {ancestor-drev-id}) to prefetch"""
     drevs = set()
     ancestordrevs = set()
     op = tree[0]
     if op == b'symbol':
         r = _parsedrev(tree[1])
         if r:
             drevs.add(r)
     elif op == b'ancestors':
         r, a = _prefetchdrevs(tree[1])
         drevs.update(r)
         ancestordrevs.update(r)
         ancestordrevs.update(a)
     else:
         for t in tree[1:]:
             r, a = _prefetchdrevs(t)
             drevs.update(r)
             ancestordrevs.update(a)
     return drevs, ancestordrevs
 
 
 def querydrev(ui, spec):
     """return a list of "Differential Revision" dicts
 
     spec is a string using a simple query language, see docstring in phabread
     for details.
 
     A "Differential Revision dict" looks like:
 
         {
             "activeDiffPHID": "PHID-DIFF-xoqnjkobbm6k4dk6hi72",
             "authorPHID": "PHID-USER-tv3ohwc4v4jeu34otlye",
             "auxiliary": {
               "phabricator:depends-on": [
                 "PHID-DREV-gbapp366kutjebt7agcd"
               ]
               "phabricator:projects": [],
             },
             "branch": "default",
             "ccs": [],
             "commits": [],
             "dateCreated": "1499181406",
             "dateModified": "1499182103",
             "diffs": [
               "3",
               "4",
             ],
             "hashes": [],
             "id": "2",
             "lineCount": "2",
             "phid": "PHID-DREV-672qvysjcczopag46qty",
             "properties": {},
             "repositoryPHID": "PHID-REPO-hub2hx62ieuqeheznasv",
             "reviewers": [],
             "sourcePath": null
             "status": "0",
             "statusName": "Needs Review",
             "summary": "",
             "testPlan": "",
             "title": "example",
             "uri": "https://phab.example.com/D2",
         }
     """
     # TODO: replace differential.query and differential.querydiffs with
     # differential.diff.search because the former (and their output) are
     # frozen, and planned to be deprecated and removed.
 
     def fetch(params):
         """params -> single drev or None"""
         key = (params.get(b'ids') or params.get(b'phids') or [None])[0]
         if key in prefetched:
             return prefetched[key]
         drevs = callconduit(ui, b'differential.query', params)
         # Fill prefetched with the result
         for drev in drevs:
             prefetched[drev[b'phid']] = drev
             prefetched[int(drev[b'id'])] = drev
         if key not in prefetched:
             raise error.Abort(
                 _(b'cannot get Differential Revision %r') % params
             )
         return prefetched[key]
 
     def getstack(topdrevids):
         """given a top, get a stack from the bottom, [id] -> [id]"""
         visited = set()
         result = []
         queue = [{b'ids': [i]} for i in topdrevids]
         while queue:
             params = queue.pop()
             drev = fetch(params)
             if drev[b'id'] in visited:
                 continue
             visited.add(drev[b'id'])
             result.append(int(drev[b'id']))
             auxiliary = drev.get(b'auxiliary', {})
             depends = auxiliary.get(b'phabricator:depends-on', [])
             for phid in depends:
                 queue.append({b'phids': [phid]})
         result.reverse()
         return smartset.baseset(result)
 
     # Initialize prefetch cache
     prefetched = {}  # {id or phid: drev}
 
     tree = _parse(spec)
     drevs, ancestordrevs = _prefetchdrevs(tree)
 
     # developer config: phabricator.batchsize
     batchsize = ui.configint(b'phabricator', b'batchsize')
 
     # Prefetch Differential Revisions in batch
     tofetch = set(drevs)
     for r in ancestordrevs:
         tofetch.update(range(max(1, r - batchsize), r + 1))
     if drevs:
         fetch({b'ids': list(tofetch)})
     validids = sorted(set(getstack(list(ancestordrevs))) | set(drevs))
 
     # Walk through the tree, return smartsets
     def walk(tree):
         op = tree[0]
         if op == b'symbol':
             drev = _parsedrev(tree[1])
             if drev:
                 return smartset.baseset([drev])
             elif tree[1] in _knownstatusnames:
                 drevs = [
                     r
                     for r in validids
                     if _getstatusname(prefetched[r]) == tree[1]
                 ]
                 return smartset.baseset(drevs)
             else:
                 raise error.Abort(_(b'unknown symbol: %s') % tree[1])
         elif op in {b'and_', b'add', b'sub'}:
             assert len(tree) == 3
             return getattr(operator, op)(walk(tree[1]), walk(tree[2]))
         elif op == b'group':
             return walk(tree[1])
         elif op == b'ancestors':
             return getstack(walk(tree[1]))
         else:
             raise error.ProgrammingError(b'illegal tree: %r' % tree)
 
     return [prefetched[r] for r in walk(tree)]
 
 
 def getdescfromdrev(drev):
     """get description (commit message) from "Differential Revision"
 
     This is similar to differential.getcommitmessage API. But we only care
     about limited fields: title, summary, test plan, and URL.
     """
     title = drev[b'title']
     summary = drev[b'summary'].rstrip()
     testplan = drev[b'testPlan'].rstrip()
     if testplan:
         testplan = b'Test Plan:\n%s' % testplan
     uri = b'Differential Revision: %s' % drev[b'uri']
     return b'\n\n'.join(filter(None, [title, summary, testplan, uri]))
 
 
 def getdiffmeta(diff):
     """get commit metadata (date, node, user, p1) from a diff object
 
     The metadata could be "hg:meta", sent by phabsend, like:
 
         "properties": {
           "hg:meta": {
             "branch": "default",
             "date": "1499571514 25200",
             "node": "98c08acae292b2faf60a279b4189beb6cff1414d",
             "user": "Foo Bar <[e-mail]>",
             "parent": "6d0abad76b30e4724a37ab8721d630394070fe16"
           }
         }
 
     Or converted from "local:commits", sent by "arc", like:
 
         "properties": {
           "local:commits": {
             "98c08acae292b2faf60a279b4189beb6cff1414d": {
               "author": "Foo Bar",
               "authorEmail": "[e-mail]"
               "branch": "default",
               "commit": "98c08acae292b2faf60a279b4189beb6cff1414d",
               "local": "1000",
               "message": "...",
               "parents": ["6d0abad76b30e4724a37ab8721d630394070fe16"],
               "rev": "98c08acae292b2faf60a279b4189beb6cff1414d",
               "summary": "...",
               "tag": "",
               "time": 1499546314,
             }
           }
         }
 
     Note: metadata extracted from "local:commits" will lose time zone
     information.
     """
     props = diff.get(b'properties') or {}
     meta = props.get(b'hg:meta')
     if not meta:
         if props.get(b'local:commits'):
             commit = sorted(props[b'local:commits'].values())[0]
             meta = {}
             if b'author' in commit and b'authorEmail' in commit:
                 meta[b'user'] = b'%s <%s>' % (
                     commit[b'author'],
                     commit[b'authorEmail'],
                 )
             if b'time' in commit:
                 meta[b'date'] = b'%d 0' % int(commit[b'time'])
             if b'branch' in commit:
                 meta[b'branch'] = commit[b'branch']
             node = commit.get(b'commit', commit.get(b'rev'))
             if node:
                 meta[b'node'] = node
             if len(commit.get(b'parents', ())) >= 1:
                 meta[b'parent'] = commit[b'parents'][0]
         else:
             meta = {}
     if b'date' not in meta and b'dateCreated' in diff:
         meta[b'date'] = b'%s 0' % diff[b'dateCreated']
     if b'branch' not in meta and diff.get(b'branch'):
         meta[b'branch'] = diff[b'branch']
     if b'parent' not in meta and diff.get(b'sourceControlBaseRevision'):
         meta[b'parent'] = diff[b'sourceControlBaseRevision']
     return meta
 
 
 def readpatch(ui, drevs, write):
     """generate plain-text patch readable by 'hg import'
 
-    write is usually ui.write. drevs is what "querydrev" returns, results of
+    write takes a list of (DREV, bytes), where DREV is the differential number
+    (as bytes, without the "D" prefix) and the bytes are the text of a patch
+    to be imported. drevs is what "querydrev" returns, results of
     "differential.query".
     """
     # Prefetch hg:meta property for all diffs
     diffids = sorted(set(max(int(v) for v in drev[b'diffs']) for drev in drevs))
     diffs = callconduit(ui, b'differential.querydiffs', {b'ids': diffids})
 
+    patches = []
+
     # Generate patch for each drev
     for drev in drevs:
         ui.note(_(b'reading D%s\n') % drev[b'id'])
 
         diffid = max(int(v) for v in drev[b'diffs'])
         body = callconduit(ui, b'differential.getrawdiff', {b'diffID': diffid})
         desc = getdescfromdrev(drev)
         header = b'# HG changeset patch\n'
 
         # Try to preserve metadata from hg:meta property. Write hg patch
         # headers that can be read by the "import" command. See patchheadermap
         # and extract in mercurial/patch.py for supported headers.
         meta = getdiffmeta(diffs[b'%d' % diffid])
         for k in _metanamemap.keys():
             if k in meta:
                 header += b'# %s %s\n' % (_metanamemap[k], meta[k])
 
         content = b'%s%s\n%s' % (header, desc, body)
-        write(content)
+        patches.append((drev[b'id'], content))
+
+    # Write patches to the supplied callback
+    write(patches)
 
 
 @vcrcommand(
     b'phabread',
     [(b'', b'stack', False, _(b'read dependencies'))],
     _(b'DREVSPEC [OPTIONS]'),
     helpcategory=command.CATEGORY_IMPORT_EXPORT,
 )
 def phabread(ui, repo, spec, **opts):
     """print patches from Phabricator suitable for importing
 
     DREVSPEC could be a Differential Revision identity, like ``D123``, or just
     the number ``123``. It could also have common operators like ``+``, ``-``,
     ``&``, ``(``, ``)`` for complex queries. Prefix ``:`` could be used to
     select a stack.
 
     ``abandoned``, ``accepted``, ``closed``, ``needsreview``, ``needsrevision``
     could be used to filter patches by status. For performance reason, they
     only represent a subset of non-status selections and cannot be used alone.
 
     For example, ``:D6+8-(2+D4)`` selects a stack up to D6, plus D8 and exclude
     D2 and D4. ``:D9 & needsreview`` selects "Needs Review" revisions in a
     stack up to D9.
 
     If --stack is given, follow dependencies information and read all patches.
     It is equivalent to the ``:`` operator.
     """
     opts = pycompat.byteskwargs(opts)
     if opts.get(b'stack'):
         spec = b':(%s)' % spec
     drevs = querydrev(repo.ui, spec)
-    readpatch(repo.ui, drevs, ui.write)
+
+    def _write(patches):
+        for drev, content in patches:
+            ui.write(content)
+
+    readpatch(repo.ui, drevs, _write)
 
 
 @vcrcommand(
     b'phabupdate',
     [
         (b'', b'accept', False, _(b'accept revisions')),
         (b'', b'reject', False, _(b'reject revisions')),
         (b'', b'abandon', False, _(b'abandon revisions')),
         (b'', b'reclaim', False, _(b'reclaim revisions')),
         (b'm', b'comment', b'', _(b'comment on the last revision')),
     ],
     _(b'DREVSPEC [OPTIONS]'),
     helpcategory=command.CATEGORY_IMPORT_EXPORT,
     optionalrepo=True,
 )
 def phabupdate(ui, repo, spec, **opts):
     """update Differential Revision in batch
 
     DREVSPEC selects revisions. See :hg:`help phabread` for its usage.
     """
     opts = pycompat.byteskwargs(opts)
     flags = [n for n in b'accept reject abandon reclaim'.split() if opts.get(n)]
     if len(flags) > 1:
         raise error.Abort(_(b'%s cannot be used together') % b', '.join(flags))
 
     actions = []
     for f in flags:
         actions.append({b'type': f, b'value': True})
 
     drevs = querydrev(ui, spec)
     for i, drev in enumerate(drevs):
         if i + 1 == len(drevs) and opts.get(b'comment'):
             actions.append({b'type': b'comment', b'value': opts[b'comment']})
         if actions:
             params = {
                 b'objectIdentifier': drev[b'phid'],
                 b'transactions': actions,
             }
             callconduit(ui, b'differential.revision.edit', params)
 
 
 @eh.templatekeyword(b'phabreview', requires={b'ctx'})
 def template_review(context, mapping):
     """:phabreview: Object describing the review for this changeset.
     Has attributes `url` and `id`.
     """
     ctx = context.resource(mapping, b'ctx')
     m = _differentialrevisiondescre.search(ctx.description())
     if m:
         return templateutil.hybriddict(
             {b'url': m.group('url'), b'id': b"D%s" % m.group('id'),}
         )
     else:
         tags = ctx.repo().nodetags(ctx.node())
         for t in tags:
             if _differentialrevisiontagre.match(t):
                 url = ctx.repo().ui.config(b'phabricator', b'url')
                 if not url.endswith(b'/'):
                     url += b'/'
                 url += t
 
                 return templateutil.hybriddict({b'url': url, b'id': t,})
     return None
 
 
 @eh.templatekeyword(b'phabstatus', requires={b'ctx', b'repo', b'ui'})
 def template_status(context, mapping):
     """:phabstatus: String. Status of Phabricator differential.
     """
     ctx = context.resource(mapping, b'ctx')
     repo = context.resource(mapping, b'repo')
     ui = context.resource(mapping, b'ui')
 
     rev = ctx.rev()
     try:
         drevid = getdrevmap(repo, [rev])[rev]
     except KeyError:
         return None
     drevs = callconduit(ui, b'differential.query', {b'ids': [drevid]})
     for drev in drevs:
         if int(drev[b'id']) == drevid:
             return templateutil.hybriddict(
                 {b'url': drev[b'uri'], b'status': drev[b'statusName'],}
             )
     return None
 
 
 @show.showview(b'phabstatus', csettopic=b'work')
 def phabstatusshowview(ui, repo, displayer):
     """Phabricator differiential status"""
     revs = repo.revs('sort(_underway(), topo)')
     drevmap = getdrevmap(repo, revs)
     unknownrevs, drevids, revsbydrevid = [], set([]), {}
     for rev, drevid in pycompat.iteritems(drevmap):
         if drevid is not None:
             drevids.add(drevid)
             revsbydrevid.setdefault(drevid, set([])).add(rev)
         else:
             unknownrevs.append(rev)
 
     drevs = callconduit(ui, b'differential.query', {b'ids': list(drevids)})
     drevsbyrev = {}
     for drev in drevs:
         for rev in revsbydrevid[int(drev[b'id'])]:
             drevsbyrev[rev] = drev
 
     def phabstatus(ctx):
         drev = drevsbyrev[ctx.rev()]
         status = ui.label(
             b'%(statusName)s' % drev,
             b'phabricator.status.%s' % _getstatusname(drev),
         )
         ui.write(b"\n%s %s\n" % (drev[b'uri'], status))
 
     revs -= smartset.baseset(unknownrevs)
     revdag = graphmod.dagwalker(repo, revs)
 
     ui.setconfig(b'experimental', b'graphshorten', True)
     displayer._exthook = phabstatus
     nodelen = show.longestshortest(repo, revs)
     logcmdutil.displaygraph(
         ui,
         repo,
         revdag,
         displayer,
         graphmod.asciiedges,
         props={b'nodelen': nodelen},
     )