view mercurial/statichttprepo.py @ 50662:12f13b13f414 stable

revlog: avoid possible collision between directory and temporary index

Since 6.4, we create a temporary index file to write the split data without
overwriting the inline version too early. However, the store encoding does not
prevent these new `.i.s` file to collide with a directory with the same name.
While the odds for such a collision to happens are fairly low, the collision
would prevent Mercurial from working.

The store encoding have a mitigation solution in place to prevent such
collisions from happening for `.i` and `.d` files, but not for other extensions.
We cannot update this encoding scheme to solve the issue since it would diverge
from older version of Mercurial.

Instead, we create an alternative directory tree dedicated to such files.
The use of the `.i` extension combined with store encoding will prevent
collisions there.

# statichttprepo.py - simple http repository class for mercurial
#
# This provides read-only repo access to repositories exported via static http
#
# Copyright 2005-2007 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.


import errno

from .i18n import _
from .node import sha1nodeconstants
from . import (
    branchmap,
    changelog,
    error,
    localrepo,
    manifest,
    namespaces,
    pathutil,
    pycompat,
    requirements as requirementsmod,
    url,
    util,
    vfs as vfsmod,
)
from .utils import (
    urlutil,
)

urlerr = util.urlerr
urlreq = util.urlreq


class httprangereader:
    def __init__(self, url, opener):
        # we assume opener has HTTPRangeHandler
        self.url = url
        self.pos = 0
        self.opener = opener
        self.name = url

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.close()

    def seek(self, pos):
        self.pos = pos

    def read(self, bytes=None):
        req = urlreq.request(pycompat.strurl(self.url))
        end = b''
        if bytes:
            end = self.pos + bytes - 1
        if self.pos or end:
            req.add_header('Range', 'bytes=%d-%s' % (self.pos, end))

        try:
            f = self.opener.open(req)
            data = f.read()
            code = f.code
        except urlerr.httperror as inst:
            num = inst.code == 404 and errno.ENOENT or None
            # Explicitly convert the exception to str as Py3 will try
            # convert it to local encoding and with as the HTTPResponse
            # instance doesn't support encode.
            raise IOError(num, str(inst))
        except urlerr.urlerror as inst:
            raise IOError(None, inst.reason)

        if code == 200:
            # HTTPRangeHandler does nothing if remote does not support
            # Range headers and returns the full entity. Let's slice it.
            if bytes:
                data = data[self.pos : self.pos + bytes]
            else:
                data = data[self.pos :]
        elif bytes:
            data = data[:bytes]
        self.pos += len(data)
        return data

    def readlines(self):
        return self.read().splitlines(True)

    def __iter__(self):
        return iter(self.readlines())

    def close(self):
        pass


# _RangeError and _HTTPRangeHandler were originally in byterange.py,
# which was itself extracted from urlgrabber. See the last version of
# byterange.py from history if you need more information.
class _RangeError(IOError):
    """Error raised when an unsatisfiable range is requested."""


class _HTTPRangeHandler(urlreq.basehandler):
    """Handler that enables HTTP Range headers.

    This was extremely simple. The Range header is a HTTP feature to
    begin with so all this class does is tell urllib2 that the
    "206 Partial Content" response from the HTTP server is what we
    expected.
    """

    def http_error_206(self, req, fp, code, msg, hdrs):
        # 206 Partial Content Response
        r = urlreq.addinfourl(fp, hdrs, req.get_full_url())
        r.code = code
        r.msg = msg
        return r

    def http_error_416(self, req, fp, code, msg, hdrs):
        # HTTP's Range Not Satisfiable error
        raise _RangeError(b'Requested Range Not Satisfiable')


def build_opener(ui, authinfo):
    # urllib cannot handle URLs with embedded user or passwd
    urlopener = url.opener(ui, authinfo)
    urlopener.add_handler(_HTTPRangeHandler())

    class statichttpvfs(vfsmod.abstractvfs):
        def __init__(self, base):
            self.base = base
            self.options = {}

        def __call__(self, path, mode=b'r', *args, **kw):
            if mode not in (b'r', b'rb'):
                raise IOError(b'Permission denied')
            f = b"/".join((self.base, urlreq.quote(path)))
            return httprangereader(f, urlopener)

        def join(self, path):
            if path:
                return pathutil.join(self.base, path)
            else:
                return self.base

    return statichttpvfs


class statichttppeer(localrepo.localpeer):
    def local(self):
        return None

    def canpush(self):
        return False


class statichttprepository(
    localrepo.localrepository, localrepo.revlogfilestorage
):
    supported = localrepo.localrepository._basesupported

    def __init__(self, ui, path):
        self._url = path
        self.ui = ui

        self.root = path
        u = urlutil.url(path.rstrip(b'/') + b"/.hg")
        self.path, authinfo = u.authinfo()

        vfsclass = build_opener(ui, authinfo)
        self.vfs = vfsclass(self.path)
        self.cachevfs = vfsclass(self.vfs.join(b'cache'))
        self._phasedefaults = []

        self.names = namespaces.namespaces()
        self.filtername = None
        self._extrafilterid = None
        self._wanted_sidedata = set()
        self.features = set()

        try:
            requirements = set(self.vfs.read(b'requires').splitlines())
        except FileNotFoundError:
            requirements = set()

            # check if it is a non-empty old-style repository
            try:
                fp = self.vfs(b"00changelog.i")
                fp.read(1)
                fp.close()
            except FileNotFoundError:
                # we do not care about empty old-style repositories here
                msg = _(b"'%s' does not appear to be an hg repository") % path
                raise error.RepoError(msg)
        if requirementsmod.SHARESAFE_REQUIREMENT in requirements:
            storevfs = vfsclass(self.vfs.join(b'store'))
            requirements |= set(storevfs.read(b'requires').splitlines())

        supportedrequirements = localrepo.gathersupportedrequirements(ui)
        localrepo.ensurerequirementsrecognized(
            requirements, supportedrequirements
        )
        localrepo.ensurerequirementscompatible(ui, requirements)
        self.nodeconstants = sha1nodeconstants
        self.nullid = self.nodeconstants.nullid

        # setup store
        self.store = localrepo.makestore(requirements, self.path, vfsclass)
        self.spath = self.store.path
        self.svfs = self.store.opener
        self.sjoin = self.store.join
        self._filecache = {}
        self.requirements = requirements

        rootmanifest = manifest.manifestrevlog(self.nodeconstants, self.svfs)
        self.manifestlog = manifest.manifestlog(
            self.svfs, self, rootmanifest, self.narrowmatch()
        )
        self.changelog = changelog.changelog(self.svfs)
        self._tags = None
        self.nodetagscache = None
        self._branchcaches = branchmap.BranchMapCache()
        self._revbranchcache = None
        self.encodepats = None
        self.decodepats = None
        self._transref = None
        self._dirstate = None

    def _restrictcapabilities(self, caps):
        caps = super(statichttprepository, self)._restrictcapabilities(caps)
        return caps.difference([b"pushkey"])

    def url(self):
        return self._url

    def local(self):
        return False

    def peer(self, path=None):
        return statichttppeer(self, path=path)

    def wlock(self, wait=True):
        raise error.LockUnavailable(
            0,
            _(b'lock not available'),
            b'lock',
            _(b'cannot lock static-http repository'),
        )

    def lock(self, wait=True):
        raise error.LockUnavailable(
            0,
            _(b'lock not available'),
            b'lock',
            _(b'cannot lock static-http repository'),
        )

    def _writecaches(self):
        pass  # statichttprepository are read only


def make_peer(ui, path, create, intents=None, createopts=None):
    if create:
        raise error.Abort(_(b'cannot create new static-http repository'))
    url = path.loc[7:]
    return statichttprepository(ui, url).peer(path=path)