view mercurial/wireprotov1server.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# wireprotov1server.py - Wire protocol version 1 server functionality
#
# Copyright 2005-2010 Olivia 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 binascii
import os

from .i18n import _
from .node import hex
from .pycompat import getattr

from . import (
    bundle2,
    bundlecaches,
    changegroup as changegroupmod,
    discovery,
    encoding,
    error,
    exchange,
    pushkey as pushkeymod,
    pycompat,
    requirements as requirementsmod,
    streamclone,
    util,
    wireprototypes,
)

from .utils import (
    procutil,
    stringutil,
)

urlerr = util.urlerr
urlreq = util.urlreq

bundle2requiredmain = _(b'incompatible Mercurial client; bundle2 required')
bundle2requiredhint = _(
    b'see https://www.mercurial-scm.org/wiki/IncompatibleClient'
)
bundle2required = b'%s\n(%s)\n' % (bundle2requiredmain, bundle2requiredhint)


def clientcompressionsupport(proto):
    """Returns a list of compression methods supported by the client.

    Returns a list of the compression methods supported by the client
    according to the protocol capabilities. If no such capability has
    been announced, fallback to the default of zlib and uncompressed.
    """
    for cap in proto.getprotocaps():
        if cap.startswith(b'comp='):
            return cap[5:].split(b',')
    return [b'zlib', b'none']


# wire protocol command can either return a string or one of these classes.


def getdispatchrepo(repo, proto, command):
    """Obtain the repo used for processing wire protocol commands.

    The intent of this function is to serve as a monkeypatch point for
    extensions that need commands to operate on different repo views under
    specialized circumstances.
    """
    viewconfig = repo.ui.config(b'server', b'view')
    return repo.filtered(viewconfig)


def dispatch(repo, proto, command):
    repo = getdispatchrepo(repo, proto, command)

    func, spec = commands[command]
    args = proto.getargs(spec)

    return func(repo, proto, *args)


def options(cmd, keys, others):
    opts = {}
    for k in keys:
        if k in others:
            opts[k] = others[k]
            del others[k]
    if others:
        procutil.stderr.write(
            b"warning: %s ignored unexpected arguments %s\n"
            % (cmd, b",".join(others))
        )
    return opts


def bundle1allowed(repo, action):
    """Whether a bundle1 operation is allowed from the server.

    Priority is:

    1. server.bundle1gd.<action> (if generaldelta active)
    2. server.bundle1.<action>
    3. server.bundle1gd (if generaldelta active)
    4. server.bundle1
    """
    ui = repo.ui
    gd = requirementsmod.GENERALDELTA_REQUIREMENT in repo.requirements

    if gd:
        v = ui.configbool(b'server', b'bundle1gd.%s' % action)
        if v is not None:
            return v

    v = ui.configbool(b'server', b'bundle1.%s' % action)
    if v is not None:
        return v

    if gd:
        v = ui.configbool(b'server', b'bundle1gd')
        if v is not None:
            return v

    return ui.configbool(b'server', b'bundle1')


commands = wireprototypes.commanddict()


def wireprotocommand(name, args=None, permission=b'push'):
    """Decorator to declare a wire protocol command.

    ``name`` is the name of the wire protocol command being provided.

    ``args`` defines the named arguments accepted by the command. It is
    a space-delimited list of argument names. ``*`` denotes a special value
    that says to accept all named arguments.

    ``permission`` defines the permission type needed to run this command.
    Can be ``push`` or ``pull``. These roughly map to read-write and read-only,
    respectively. Default is to assume command requires ``push`` permissions
    because otherwise commands not declaring their permissions could modify
    a repository that is supposed to be read-only.
    """
    transports = {
        k for k, v in wireprototypes.TRANSPORTS.items() if v[b'version'] == 1
    }

    if permission not in (b'push', b'pull'):
        raise error.ProgrammingError(
            b'invalid wire protocol permission; '
            b'got %s; expected "push" or "pull"' % permission
        )

    if args is None:
        args = b''

    if not isinstance(args, bytes):
        raise error.ProgrammingError(
            b'arguments for version 1 commands must be declared as bytes'
        )

    def register(func):
        if name in commands:
            raise error.ProgrammingError(
                b'%s command already registered for version 1' % name
            )
        commands[name] = wireprototypes.commandentry(
            func, args=args, transports=transports, permission=permission
        )

        return func

    return register


# TODO define a more appropriate permissions type to use for this.
@wireprotocommand(b'batch', b'cmds *', permission=b'pull')
def batch(repo, proto, cmds, others):
    unescapearg = wireprototypes.unescapebatcharg
    res = []
    for pair in cmds.split(b';'):
        op, args = pair.split(b' ', 1)
        vals = {}
        for a in args.split(b','):
            if a:
                n, v = a.split(b'=')
                vals[unescapearg(n)] = unescapearg(v)
        func, spec = commands[op]

        # Validate that client has permissions to perform this command.
        perm = commands[op].permission
        assert perm in (b'push', b'pull')
        proto.checkperm(perm)

        if spec:
            keys = spec.split()
            data = {}
            for k in keys:
                if k == b'*':
                    star = {}
                    for key in vals.keys():
                        if key not in keys:
                            star[key] = vals[key]
                    data[b'*'] = star
                else:
                    data[k] = vals[k]
            result = func(repo, proto, *[data[k] for k in keys])
        else:
            result = func(repo, proto)
        if isinstance(result, wireprototypes.ooberror):
            return result

        # For now, all batchable commands must return bytesresponse or
        # raw bytes (for backwards compatibility).
        assert isinstance(result, (wireprototypes.bytesresponse, bytes))
        if isinstance(result, wireprototypes.bytesresponse):
            result = result.data
        res.append(wireprototypes.escapebatcharg(result))

    return wireprototypes.bytesresponse(b';'.join(res))


@wireprotocommand(b'between', b'pairs', permission=b'pull')
def between(repo, proto, pairs):
    pairs = [wireprototypes.decodelist(p, b'-') for p in pairs.split(b" ")]
    r = []
    for b in repo.between(pairs):
        r.append(wireprototypes.encodelist(b) + b"\n")

    return wireprototypes.bytesresponse(b''.join(r))


@wireprotocommand(b'branchmap', permission=b'pull')
def branchmap(repo, proto):
    branchmap = repo.branchmap()
    heads = []
    for branch, nodes in pycompat.iteritems(branchmap):
        branchname = urlreq.quote(encoding.fromlocal(branch))
        branchnodes = wireprototypes.encodelist(nodes)
        heads.append(b'%s %s' % (branchname, branchnodes))

    return wireprototypes.bytesresponse(b'\n'.join(heads))


@wireprotocommand(b'branches', b'nodes', permission=b'pull')
def branches(repo, proto, nodes):
    nodes = wireprototypes.decodelist(nodes)
    r = []
    for b in repo.branches(nodes):
        r.append(wireprototypes.encodelist(b) + b"\n")

    return wireprototypes.bytesresponse(b''.join(r))


@wireprotocommand(b'clonebundles', b'', permission=b'pull')
def clonebundles(repo, proto):
    """Server command for returning info for available bundles to seed clones.

    Clients will parse this response and determine what bundle to fetch.

    Extensions may wrap this command to filter or dynamically emit data
    depending on the request. e.g. you could advertise URLs for the closest
    data center given the client's IP address.
    """
    return wireprototypes.bytesresponse(
        repo.vfs.tryread(bundlecaches.CB_MANIFEST_FILE)
    )


wireprotocaps = [
    b'lookup',
    b'branchmap',
    b'pushkey',
    b'known',
    b'getbundle',
    b'unbundlehash',
]


def _capabilities(repo, proto):
    """return a list of capabilities for a repo

    This function exists to allow extensions to easily wrap capabilities
    computation

    - returns a lists: easy to alter
    - change done here will be propagated to both `capabilities` and `hello`
      command without any other action needed.
    """
    # copy to prevent modification of the global list
    caps = list(wireprotocaps)

    # Command of same name as capability isn't exposed to version 1 of
    # transports. So conditionally add it.
    if commands.commandavailable(b'changegroupsubset', proto):
        caps.append(b'changegroupsubset')

    if streamclone.allowservergeneration(repo):
        if repo.ui.configbool(b'server', b'preferuncompressed'):
            caps.append(b'stream-preferred')
        requiredformats = streamclone.streamed_requirements(repo)
        # if our local revlogs are just revlogv1, add 'stream' cap
        if not requiredformats - {requirementsmod.REVLOGV1_REQUIREMENT}:
            caps.append(b'stream')
        # otherwise, add 'streamreqs' detailing our local revlog format
        else:
            caps.append(b'streamreqs=%s' % b','.join(sorted(requiredformats)))
    if repo.ui.configbool(b'experimental', b'bundle2-advertise'):
        capsblob = bundle2.encodecaps(bundle2.getrepocaps(repo, role=b'server'))
        caps.append(b'bundle2=' + urlreq.quote(capsblob))
    caps.append(b'unbundle=%s' % b','.join(bundle2.bundlepriority))

    if repo.ui.configbool(b'experimental', b'narrow'):
        caps.append(wireprototypes.NARROWCAP)
        if repo.ui.configbool(b'experimental', b'narrowservebrokenellipses'):
            caps.append(wireprototypes.ELLIPSESCAP)

    return proto.addcapabilities(repo, caps)


# If you are writing an extension and consider wrapping this function. Wrap
# `_capabilities` instead.
@wireprotocommand(b'capabilities', permission=b'pull')
def capabilities(repo, proto):
    caps = _capabilities(repo, proto)
    return wireprototypes.bytesresponse(b' '.join(sorted(caps)))


@wireprotocommand(b'changegroup', b'roots', permission=b'pull')
def changegroup(repo, proto, roots):
    nodes = wireprototypes.decodelist(roots)
    outgoing = discovery.outgoing(
        repo, missingroots=nodes, ancestorsof=repo.heads()
    )
    cg = changegroupmod.makechangegroup(repo, outgoing, b'01', b'serve')
    gen = iter(lambda: cg.read(32768), b'')
    return wireprototypes.streamres(gen=gen)


@wireprotocommand(b'changegroupsubset', b'bases heads', permission=b'pull')
def changegroupsubset(repo, proto, bases, heads):
    bases = wireprototypes.decodelist(bases)
    heads = wireprototypes.decodelist(heads)
    outgoing = discovery.outgoing(repo, missingroots=bases, ancestorsof=heads)
    cg = changegroupmod.makechangegroup(repo, outgoing, b'01', b'serve')
    gen = iter(lambda: cg.read(32768), b'')
    return wireprototypes.streamres(gen=gen)


@wireprotocommand(b'debugwireargs', b'one two *', permission=b'pull')
def debugwireargs(repo, proto, one, two, others):
    # only accept optional args from the known set
    opts = options(b'debugwireargs', [b'three', b'four'], others)
    return wireprototypes.bytesresponse(
        repo.debugwireargs(one, two, **pycompat.strkwargs(opts))
    )


def find_pullbundle(repo, proto, opts, clheads, heads, common):
    """Return a file object for the first matching pullbundle.

    Pullbundles are specified in .hg/pullbundles.manifest similar to
    clonebundles.
    For each entry, the bundle specification is checked for compatibility:
    - Client features vs the BUNDLESPEC.
    - Revisions shared with the clients vs base revisions of the bundle.
      A bundle can be applied only if all its base revisions are known by
      the client.
    - At least one leaf of the bundle's DAG is missing on the client.
    - Every leaf of the bundle's DAG is part of node set the client wants.
      E.g. do not send a bundle of all changes if the client wants only
      one specific branch of many.
    """

    def decodehexstring(s):
        return {binascii.unhexlify(h) for h in s.split(b';')}

    manifest = repo.vfs.tryread(b'pullbundles.manifest')
    if not manifest:
        return None
    res = bundlecaches.parseclonebundlesmanifest(repo, manifest)
    res = bundlecaches.filterclonebundleentries(repo, res)
    if not res:
        return None
    cl = repo.unfiltered().changelog
    heads_anc = cl.ancestors([cl.rev(rev) for rev in heads], inclusive=True)
    common_anc = cl.ancestors([cl.rev(rev) for rev in common], inclusive=True)
    compformats = clientcompressionsupport(proto)
    for entry in res:
        comp = entry.get(b'COMPRESSION')
        altcomp = util.compengines._bundlenames.get(comp)
        if comp and comp not in compformats and altcomp not in compformats:
            continue
        # No test yet for VERSION, since V2 is supported by any client
        # that advertises partial pulls
        if b'heads' in entry:
            try:
                bundle_heads = decodehexstring(entry[b'heads'])
            except TypeError:
                # Bad heads entry
                continue
            if bundle_heads.issubset(common):
                continue  # Nothing new
            if all(cl.rev(rev) in common_anc for rev in bundle_heads):
                continue  # Still nothing new
            if any(
                cl.rev(rev) not in heads_anc and cl.rev(rev) not in common_anc
                for rev in bundle_heads
            ):
                continue
        if b'bases' in entry:
            try:
                bundle_bases = decodehexstring(entry[b'bases'])
            except TypeError:
                # Bad bases entry
                continue
            if not all(cl.rev(rev) in common_anc for rev in bundle_bases):
                continue
        path = entry[b'URL']
        repo.ui.debug(b'sending pullbundle "%s"\n' % path)
        try:
            return repo.vfs.open(path)
        except IOError:
            repo.ui.debug(b'pullbundle "%s" not accessible\n' % path)
            continue
    return None


@wireprotocommand(b'getbundle', b'*', permission=b'pull')
def getbundle(repo, proto, others):
    opts = options(
        b'getbundle', wireprototypes.GETBUNDLE_ARGUMENTS.keys(), others
    )
    for k, v in pycompat.iteritems(opts):
        keytype = wireprototypes.GETBUNDLE_ARGUMENTS[k]
        if keytype == b'nodes':
            opts[k] = wireprototypes.decodelist(v)
        elif keytype == b'csv':
            opts[k] = list(v.split(b','))
        elif keytype == b'scsv':
            opts[k] = set(v.split(b','))
        elif keytype == b'boolean':
            # Client should serialize False as '0', which is a non-empty string
            # so it evaluates as a True bool.
            if v == b'0':
                opts[k] = False
            else:
                opts[k] = bool(v)
        elif keytype != b'plain':
            raise KeyError(b'unknown getbundle option type %s' % keytype)

    if not bundle1allowed(repo, b'pull'):
        if not exchange.bundle2requested(opts.get(b'bundlecaps')):
            if proto.name == b'http-v1':
                return wireprototypes.ooberror(bundle2required)
            raise error.Abort(bundle2requiredmain, hint=bundle2requiredhint)

    try:
        clheads = set(repo.changelog.heads())
        heads = set(opts.get(b'heads', set()))
        common = set(opts.get(b'common', set()))
        common.discard(repo.nullid)
        if (
            repo.ui.configbool(b'server', b'pullbundle')
            and b'partial-pull' in proto.getprotocaps()
        ):
            # Check if a pre-built bundle covers this request.
            bundle = find_pullbundle(repo, proto, opts, clheads, heads, common)
            if bundle:
                return wireprototypes.streamres(
                    gen=util.filechunkiter(bundle), prefer_uncompressed=True
                )

        if repo.ui.configbool(b'server', b'disablefullbundle'):
            # Check to see if this is a full clone.
            changegroup = opts.get(b'cg', True)
            if changegroup and not common and clheads == heads:
                raise error.Abort(
                    _(b'server has pull-based clones disabled'),
                    hint=_(b'remove --pull if specified or upgrade Mercurial'),
                )

        info, chunks = exchange.getbundlechunks(
            repo, b'serve', **pycompat.strkwargs(opts)
        )
        prefercompressed = info.get(b'prefercompressed', True)
    except error.Abort as exc:
        # cleanly forward Abort error to the client
        if not exchange.bundle2requested(opts.get(b'bundlecaps')):
            if proto.name == b'http-v1':
                return wireprototypes.ooberror(exc.message + b'\n')
            raise  # cannot do better for bundle1 + ssh
        # bundle2 request expect a bundle2 reply
        bundler = bundle2.bundle20(repo.ui)
        manargs = [(b'message', exc.message)]
        advargs = []
        if exc.hint is not None:
            advargs.append((b'hint', exc.hint))
        bundler.addpart(bundle2.bundlepart(b'error:abort', manargs, advargs))
        chunks = bundler.getchunks()
        prefercompressed = False

    return wireprototypes.streamres(
        gen=chunks, prefer_uncompressed=not prefercompressed
    )


@wireprotocommand(b'heads', permission=b'pull')
def heads(repo, proto):
    h = repo.heads()
    return wireprototypes.bytesresponse(wireprototypes.encodelist(h) + b'\n')


@wireprotocommand(b'hello', permission=b'pull')
def hello(repo, proto):
    """Called as part of SSH handshake to obtain server info.

    Returns a list of lines describing interesting things about the
    server, in an RFC822-like format.

    Currently, the only one defined is ``capabilities``, which consists of a
    line of space separated tokens describing server abilities:

        capabilities: <token0> <token1> <token2>
    """
    caps = capabilities(repo, proto).data
    return wireprototypes.bytesresponse(b'capabilities: %s\n' % caps)


@wireprotocommand(b'listkeys', b'namespace', permission=b'pull')
def listkeys(repo, proto, namespace):
    d = sorted(repo.listkeys(encoding.tolocal(namespace)).items())
    return wireprototypes.bytesresponse(pushkeymod.encodekeys(d))


@wireprotocommand(b'lookup', b'key', permission=b'pull')
def lookup(repo, proto, key):
    try:
        k = encoding.tolocal(key)
        n = repo.lookup(k)
        r = hex(n)
        success = 1
    except Exception as inst:
        r = stringutil.forcebytestr(inst)
        success = 0
    return wireprototypes.bytesresponse(b'%d %s\n' % (success, r))


@wireprotocommand(b'known', b'nodes *', permission=b'pull')
def known(repo, proto, nodes, others):
    v = b''.join(
        b and b'1' or b'0' for b in repo.known(wireprototypes.decodelist(nodes))
    )
    return wireprototypes.bytesresponse(v)


@wireprotocommand(b'protocaps', b'caps', permission=b'pull')
def protocaps(repo, proto, caps):
    if proto.name == wireprototypes.SSHV1:
        proto._protocaps = set(caps.split(b' '))
    return wireprototypes.bytesresponse(b'OK')


@wireprotocommand(b'pushkey', b'namespace key old new', permission=b'push')
def pushkey(repo, proto, namespace, key, old, new):
    # compatibility with pre-1.8 clients which were accidentally
    # sending raw binary nodes rather than utf-8-encoded hex
    if len(new) == 20 and stringutil.escapestr(new) != new:
        # looks like it could be a binary node
        try:
            new.decode('utf-8')
            new = encoding.tolocal(new)  # but cleanly decodes as UTF-8
        except UnicodeDecodeError:
            pass  # binary, leave unmodified
    else:
        new = encoding.tolocal(new)  # normal path

    with proto.mayberedirectstdio() as output:
        r = (
            repo.pushkey(
                encoding.tolocal(namespace),
                encoding.tolocal(key),
                encoding.tolocal(old),
                new,
            )
            or False
        )

    output = output.getvalue() if output else b''
    return wireprototypes.bytesresponse(b'%d\n%s' % (int(r), output))


@wireprotocommand(b'stream_out', permission=b'pull')
def stream(repo, proto):
    """If the server supports streaming clone, it advertises the "stream"
    capability with a value representing the version and flags of the repo
    it is serving. Client checks to see if it understands the format.
    """
    return wireprototypes.streamreslegacy(streamclone.generatev1wireproto(repo))


@wireprotocommand(b'unbundle', b'heads', permission=b'push')
def unbundle(repo, proto, heads):
    their_heads = wireprototypes.decodelist(heads)

    with proto.mayberedirectstdio() as output:
        try:
            exchange.check_heads(repo, their_heads, b'preparing changes')
            cleanup = lambda: None
            try:
                payload = proto.getpayload()
                if repo.ui.configbool(b'server', b'streamunbundle'):

                    def cleanup():
                        # Ensure that the full payload is consumed, so
                        # that the connection doesn't contain trailing garbage.
                        for p in payload:
                            pass

                    fp = util.chunkbuffer(payload)
                else:
                    # write bundle data to temporary file as it can be big
                    fp, tempname = None, None

                    def cleanup():
                        if fp:
                            fp.close()
                        if tempname:
                            os.unlink(tempname)

                    fd, tempname = pycompat.mkstemp(prefix=b'hg-unbundle-')
                    repo.ui.debug(
                        b'redirecting incoming bundle to %s\n' % tempname
                    )
                    fp = os.fdopen(fd, pycompat.sysstr(b'wb+'))
                    for p in payload:
                        fp.write(p)
                    fp.seek(0)

                gen = exchange.readbundle(repo.ui, fp, None)
                if isinstance(
                    gen, changegroupmod.cg1unpacker
                ) and not bundle1allowed(repo, b'push'):
                    if proto.name == b'http-v1':
                        # need to special case http because stderr do not get to
                        # the http client on failed push so we need to abuse
                        # some other error type to make sure the message get to
                        # the user.
                        return wireprototypes.ooberror(bundle2required)
                    raise error.Abort(
                        bundle2requiredmain, hint=bundle2requiredhint
                    )

                r = exchange.unbundle(
                    repo, gen, their_heads, b'serve', proto.client()
                )
                if util.safehasattr(r, b'addpart'):
                    # The return looks streamable, we are in the bundle2 case
                    # and should return a stream.
                    return wireprototypes.streamreslegacy(gen=r.getchunks())
                return wireprototypes.pushres(
                    r, output.getvalue() if output else b''
                )

            finally:
                cleanup()

        except (error.BundleValueError, error.Abort, error.PushRaced) as exc:
            # handle non-bundle2 case first
            if not getattr(exc, 'duringunbundle2', False):
                try:
                    raise
                except error.Abort as exc:
                    # The old code we moved used procutil.stderr directly.
                    # We did not change it to minimise code change.
                    # This need to be moved to something proper.
                    # Feel free to do it.
                    procutil.stderr.write(exc.format())
                    procutil.stderr.flush()
                    return wireprototypes.pushres(
                        0, output.getvalue() if output else b''
                    )
                except error.PushRaced:
                    return wireprototypes.pusherr(
                        pycompat.bytestr(exc),
                        output.getvalue() if output else b'',
                    )

            bundler = bundle2.bundle20(repo.ui)
            for out in getattr(exc, '_bundle2salvagedoutput', ()):
                bundler.addpart(out)
            try:
                try:
                    raise
                except error.PushkeyFailed as exc:
                    # check client caps
                    remotecaps = getattr(exc, '_replycaps', None)
                    if (
                        remotecaps is not None
                        and b'pushkey' not in remotecaps.get(b'error', ())
                    ):
                        # no support remote side, fallback to Abort handler.
                        raise
                    part = bundler.newpart(b'error:pushkey')
                    part.addparam(b'in-reply-to', exc.partid)
                    if exc.namespace is not None:
                        part.addparam(
                            b'namespace', exc.namespace, mandatory=False
                        )
                    if exc.key is not None:
                        part.addparam(b'key', exc.key, mandatory=False)
                    if exc.new is not None:
                        part.addparam(b'new', exc.new, mandatory=False)
                    if exc.old is not None:
                        part.addparam(b'old', exc.old, mandatory=False)
                    if exc.ret is not None:
                        part.addparam(b'ret', exc.ret, mandatory=False)
            except error.BundleValueError as exc:
                errpart = bundler.newpart(b'error:unsupportedcontent')
                if exc.parttype is not None:
                    errpart.addparam(b'parttype', exc.parttype)
                if exc.params:
                    errpart.addparam(b'params', b'\0'.join(exc.params))
            except error.Abort as exc:
                manargs = [(b'message', exc.message)]
                advargs = []
                if exc.hint is not None:
                    advargs.append((b'hint', exc.hint))
                bundler.addpart(
                    bundle2.bundlepart(b'error:abort', manargs, advargs)
                )
            except error.PushRaced as exc:
                bundler.newpart(
                    b'error:pushraced',
                    [(b'message', stringutil.forcebytestr(exc))],
                )
            return wireprototypes.streamreslegacy(gen=bundler.getchunks())