view mercurial/httpconnection.py @ 47799:3fffb48539ee stable

rust-nodemap: falling back to C impl as mitigation

This is a mitigation for https://bz.mercurial-scm.org/show_bug.cgi?id=6554

We see sometimes almost all data except the most recent revisions
removed from the persistent nodemap, but we don't know how to
reproduce yet.

This has sadly repercussions beyond just needing to reconstruct the
persistent nodemap: for instance, this automatically filters out
all bookmarks pointing to revisions that the nodemap cannot resolve.
If such filtering happens in a transaction, the update of the
bookmarks file that happens at the end of transaction loses all
bookmarks that have been affected. There may be similar consequences
for other data.

So this is a data loss, something that we have to prevent as soon as
possible.

As a mitigation measure, we will now fallback to the C implementation
in case nodemap lookups failed. This will add some latency, e.g., in
discovery, yet less than disabling the persistent nodemap entirely.

We considered implementing the fallback directly on the Python
side, but `revlog.get_rev()` is not systematically used, there are
also several direct calls to the index method (`self.index.rev()` for
a `revlog` instance). It is therefore more direct to implement the
mitigation in the rust-cpython wrapper.

Differential Revision: https://phab.mercurial-scm.org/D11238

# httpconnection.py - urllib2 handler for new http support
#
# Copyright 2005, 2006, 2007, 2008 Olivia Mackall <[e-mail]>
# Copyright 2006, 2007 Alexis S. L. Carvalho <[e-mail]>
# Copyright 2006 Vadim Gelfer <[e-mail]>
# Copyright 2011 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import os

from .i18n import _
from .pycompat import open
from . import (
    pycompat,
    util,
)
from .utils import (
    urlutil,
)


urlerr = util.urlerr
urlreq = util.urlreq

# moved here from url.py to avoid a cycle
class httpsendfile(object):
    """This is a wrapper around the objects returned by python's "open".

    Its purpose is to send file-like objects via HTTP.
    It do however not define a __len__ attribute because the length
    might be more than Py_ssize_t can handle.
    """

    def __init__(self, ui, *args, **kwargs):
        self.ui = ui
        self._data = open(*args, **kwargs)
        self.seek = self._data.seek
        self.close = self._data.close
        self.write = self._data.write
        self.length = os.fstat(self._data.fileno()).st_size
        self._pos = 0
        self._progress = self._makeprogress()

    def _makeprogress(self):
        # We pass double the max for total because we currently have
        # to send the bundle twice in the case of a server that
        # requires authentication. Since we can't know until we try
        # once whether authentication will be required, just lie to
        # the user and maybe the push succeeds suddenly at 50%.
        return self.ui.makeprogress(
            _(b'sending'), unit=_(b'kb'), total=(self.length // 1024 * 2)
        )

    def read(self, *args, **kwargs):
        ret = self._data.read(*args, **kwargs)
        if not ret:
            self._progress.complete()
            return ret
        self._pos += len(ret)
        self._progress.update(self._pos // 1024)
        return ret

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()


# moved here from url.py to avoid a cycle
def readauthforuri(ui, uri, user):
    uri = pycompat.bytesurl(uri)
    # Read configuration
    groups = {}
    for key, val in ui.configitems(b'auth'):
        if key in (b'cookiefile',):
            continue

        if b'.' not in key:
            ui.warn(_(b"ignoring invalid [auth] key '%s'\n") % key)
            continue
        group, setting = key.rsplit(b'.', 1)
        gdict = groups.setdefault(group, {})
        if setting in (b'username', b'cert', b'key'):
            val = util.expandpath(val)
        gdict[setting] = val

    # Find the best match
    scheme, hostpath = uri.split(b'://', 1)
    bestuser = None
    bestlen = 0
    bestauth = None
    for group, auth in pycompat.iteritems(groups):
        if user and user != auth.get(b'username', user):
            # If a username was set in the URI, the entry username
            # must either match it or be unset
            continue
        prefix = auth.get(b'prefix')
        if not prefix:
            continue

        prefixurl = urlutil.url(prefix)
        if prefixurl.user and prefixurl.user != user:
            # If a username was set in the prefix, it must match the username in
            # the URI.
            continue

        # The URI passed in has been stripped of credentials, so erase the user
        # here to allow simpler matching.
        prefixurl.user = None
        prefix = bytes(prefixurl)

        p = prefix.split(b'://', 1)
        if len(p) > 1:
            schemes, prefix = [p[0]], p[1]
        else:
            schemes = (auth.get(b'schemes') or b'https').split()
        if (
            (prefix == b'*' or hostpath.startswith(prefix))
            and (
                len(prefix) > bestlen
                or (
                    len(prefix) == bestlen
                    and not bestuser
                    and b'username' in auth
                )
            )
            and scheme in schemes
        ):
            bestlen = len(prefix)
            bestauth = group, auth
            bestuser = auth.get(b'username')
            if user and not bestuser:
                auth[b'username'] = user
    return bestauth