view hgext/factotum.py @ 43913:4b7d5d10c45d

exchange: ensure all outgoing subrepo references are present before pushing

We've run into occasional problems with people committing a repo, and then
amending or rebasing in the subrepo.  That makes it so that the revision in the
parent can't be checked out, and the problem gets propagated on push.  Mercurial
already tries to defend against this sort of dangling reference by pushing *all*
subrepo revisions first.  This reuses the checks that trigger warnings in
`hg verify` to bail on the push unless using `--force`.

I thought about putting this on the server side, but at that point, all of the
data has been transferred, only to bail out.  Additionally, SCM Manager hosts
subrepos in a location that isn't nested in the parent, so normal subrepo code
would complain that the subrepo is missing when run on the server.

Because the push command pushes subrepos before calling this exchange code, a
subrepo will be pushed before the parent is verified.  Not great, but no
dangling references are exchanged, so it solves the problem.  This code isn't in
the loop that pushes the subrepos because:

  1) the list of outgoing revisions is needed to limit the scope of the check
  2) the loop only accesses the current revision, and therefore can miss
     subrepos that were dropped in previous commits
  3) this code is called when pushing a subrepo, so the protection is recursive

I'm not sure if there's a cheap check for the list of files in the outgoing
bundle.  If there is, that would provide a fast path to bypass this check for
people not using subrepos (or if no subrepo changes were made).  There's
probably also room for verifying other references like tags.  But since that
doesn't break checkouts, it's much less of a problem.

Differential Revision: https://phab.mercurial-scm.org/D7616

# factotum.py - Plan 9 factotum integration for Mercurial
#
# Copyright (C) 2012 Steven Stallion <[e-mail]>
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

'''http authentication with factotum

This extension allows the factotum(4) facility on Plan 9 from Bell Labs
platforms to provide authentication information for HTTP access. Configuration
entries specified in the auth section as well as authentication information
provided in the repository URL are fully supported. If no prefix is specified,
a value of "*" will be assumed.

By default, keys are specified as::

  proto=pass service=hg prefix=<prefix> user=<username> !password=<password>

If the factotum extension is unable to read the required key, one will be
requested interactively.

A configuration section is available to customize runtime behavior. By
default, these entries are::

  [factotum]
  executable = /bin/auth/factotum
  mountpoint = /mnt/factotum
  service = hg

The executable entry defines the full path to the factotum binary. The
mountpoint entry defines the path to the factotum file service. Lastly, the
service entry controls the service name used when reading keys.

'''

from __future__ import absolute_import

import os
from mercurial.i18n import _
from mercurial.pycompat import setattr
from mercurial.utils import procutil
from mercurial import (
    error,
    httpconnection,
    registrar,
    url,
    util,
)

urlreq = util.urlreq
passwordmgr = url.passwordmgr

ERRMAX = 128

_executable = _mountpoint = _service = None

configtable = {}
configitem = registrar.configitem(configtable)

configitem(
    b'factotum', b'executable', default=b'/bin/auth/factotum',
)
configitem(
    b'factotum', b'mountpoint', default=b'/mnt/factotum',
)
configitem(
    b'factotum', b'service', default=b'hg',
)


def auth_getkey(self, params):
    if not self.ui.interactive():
        raise error.Abort(_(b'factotum not interactive'))
    if b'user=' not in params:
        params = b'%s user?' % params
    params = b'%s !password?' % params
    os.system(procutil.tonativestr(b"%s -g '%s'" % (_executable, params)))


def auth_getuserpasswd(self, getkey, params):
    params = b'proto=pass %s' % params
    while True:
        fd = os.open(b'%s/rpc' % _mountpoint, os.O_RDWR)
        try:
            os.write(fd, b'start %s' % params)
            l = os.read(fd, ERRMAX).split()
            if l[0] == b'ok':
                os.write(fd, b'read')
                status, user, passwd = os.read(fd, ERRMAX).split(None, 2)
                if status == b'ok':
                    if passwd.startswith(b"'"):
                        if passwd.endswith(b"'"):
                            passwd = passwd[1:-1].replace(b"''", b"'")
                        else:
                            raise error.Abort(_(b'malformed password string'))
                    return (user, passwd)
        except (OSError, IOError):
            raise error.Abort(_(b'factotum not responding'))
        finally:
            os.close(fd)
        getkey(self, params)


def monkeypatch_method(cls):
    def decorator(func):
        setattr(cls, func.__name__, func)
        return func

    return decorator


@monkeypatch_method(passwordmgr)
def find_user_password(self, realm, authuri):
    user, passwd = self.passwddb.find_user_password(realm, authuri)
    if user and passwd:
        self._writedebug(user, passwd)
        return (user, passwd)

    prefix = b''
    res = httpconnection.readauthforuri(self.ui, authuri, user)
    if res:
        _, auth = res
        prefix = auth.get(b'prefix')
        user, passwd = auth.get(b'username'), auth.get(b'password')
    if not user or not passwd:
        if not prefix:
            prefix = realm.split(b' ')[0].lower()
        params = b'service=%s prefix=%s' % (_service, prefix)
        if user:
            params = b'%s user=%s' % (params, user)
        user, passwd = auth_getuserpasswd(self, auth_getkey, params)

    self.add_password(realm, authuri, user, passwd)
    self._writedebug(user, passwd)
    return (user, passwd)


def uisetup(ui):
    global _executable
    _executable = ui.config(b'factotum', b'executable')
    global _mountpoint
    _mountpoint = ui.config(b'factotum', b'mountpoint')
    global _service
    _service = ui.config(b'factotum', b'service')