view mercurial/repoview.py @ 22506:6e1fbcb18a75 stable

hgweb: fail if an invalid command was supplied in url path (issue4071)

Traditionally, the way to specify a command for hgweb was to use url query
arguments (e.g. "?cmd=batch"). If the command is unknown to hgweb, it gives an
error (e.g. "400 no such method: badcmd").

But there's also another way to specify a command: as a url path fragment (e.g.
"/graph"). Before, hgweb was made forgiving (looks like it was made in
44c5157474e7) and user could put any unknown command in the url. If hgweb
couldn't understand it, it would just silently fall back to the default
command, which depends on the actual style (e.g. for paper it's shortlog, for
monoblue it's summary). This was inconsistent and was breaking some tools that
rely on http status codes (as noted in the issue4071). So this patch changes
that behavior to the more consistent one, i.e. hgweb will now return "400 no
such method: badcmd".

So if some tool was relying on having an invalid command return http status
code 200 and also have some information, then it will stop working. That is, if
somebody typed foobar when they really meant shortlog (and the user was lucky
enough to choose a style where the default command is shortlog too), that fact
will now be revealed.

Code-wise, the changed if block is only relevant when there's no "?cmd" query
parameter (i.e. only when command is specified as a url path fragment), and
looks like the removed else branch was there only for falling back to default
command. With that removed, the rest of the code works as expected: it looks at
the command, and if it's not known, raises a proper ErrorResponse exception
with an appropriate message.

Evidently, there were no tests that required the old behavior. But, frankly, I
don't know any way to tell if anyone actually exploited such forgiving behavior
in some in-house tool.

# repoview.py - Filtered view of a localrepo object
#
# Copyright 2012 Pierre-Yves David <[e-mail]>
#                Logilab SA        <[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 copy
import phases
import util
import obsolete
import tags as tagsmod


def hideablerevs(repo):
    """Revisions candidates to be hidden

    This is a standalone function to help extensions to wrap it."""
    return obsolete.getrevs(repo, 'obsolete')

def _gethiddenblockers(repo):
    """Get revisions that will block hidden changesets from being filtered

    This is a standalone function to help extensions to wrap it."""
    assert not repo.changelog.filteredrevs
    hideable = hideablerevs(repo)
    blockers = []
    if hideable:
        # We use cl to avoid recursive lookup from repo[xxx]
        cl = repo.changelog
        firsthideable = min(hideable)
        revs = cl.revs(start=firsthideable)
        tofilter = repo.revs(
            '(%ld) and children(%ld)', list(revs), list(hideable))
        blockers = [r for r in tofilter if r not in hideable]
        for par in repo[None].parents():
            blockers.append(par.rev())
        for bm in repo._bookmarks.values():
            blockers.append(cl.rev(bm))
        tags = {}
        tagsmod.readlocaltags(repo.ui, repo, tags, {})
        if tags:
            rev, nodemap = cl.rev, cl.nodemap
            blockers.extend(rev(t[0]) for t in tags.values() if t[0] in nodemap)
    return blockers

def computehidden(repo):
    """compute the set of hidden revision to filter

    During most operation hidden should be filtered."""
    assert not repo.changelog.filteredrevs
    hideable = hideablerevs(repo)
    if hideable:
        cl = repo.changelog
        blocked = cl.ancestors(_gethiddenblockers(repo), inclusive=True)
        return frozenset(r for r in hideable if r not in blocked)
    return frozenset()

def computeunserved(repo):
    """compute the set of revision that should be filtered when used a server

    Secret and hidden changeset should not pretend to be here."""
    assert not repo.changelog.filteredrevs
    # fast path in simple case to avoid impact of non optimised code
    hiddens = filterrevs(repo, 'visible')
    if phases.hassecret(repo):
        cl = repo.changelog
        secret = phases.secret
        getphase = repo._phasecache.phase
        first = min(cl.rev(n) for n in repo._phasecache.phaseroots[secret])
        revs = cl.revs(start=first)
        secrets = set(r for r in revs if getphase(repo, r) >= secret)
        return frozenset(hiddens | secrets)
    else:
        return hiddens

def computemutable(repo):
    """compute the set of revision that should be filtered when used a server

    Secret and hidden changeset should not pretend to be here."""
    assert not repo.changelog.filteredrevs
    # fast check to avoid revset call on huge repo
    if util.any(repo._phasecache.phaseroots[1:]):
        getphase = repo._phasecache.phase
        maymutable = filterrevs(repo, 'base')
        return frozenset(r for r in maymutable if getphase(repo, r))
    return frozenset()

def computeimpactable(repo):
    """Everything impactable by mutable revision

    The immutable filter still have some chance to get invalidated. This will
    happen when:

    - you garbage collect hidden changeset,
    - public phase is moved backward,
    - something is changed in the filtering (this could be fixed)

    This filter out any mutable changeset and any public changeset that may be
    impacted by something happening to a mutable revision.

    This is achieved by filtered everything with a revision number egal or
    higher than the first mutable changeset is filtered."""
    assert not repo.changelog.filteredrevs
    cl = repo.changelog
    firstmutable = len(cl)
    for roots in repo._phasecache.phaseroots[1:]:
        if roots:
            firstmutable = min(firstmutable, min(cl.rev(r) for r in roots))
    # protect from nullrev root
    firstmutable = max(0, firstmutable)
    return frozenset(xrange(firstmutable, len(cl)))

# function to compute filtered set
#
# When adding a new filter you MUST update the table at:
#     mercurial.branchmap.subsettable
# Otherwise your filter will have to recompute all its branches cache
# from scratch (very slow).
filtertable = {'visible': computehidden,
               'served': computeunserved,
               'immutable':  computemutable,
               'base':  computeimpactable}

def filterrevs(repo, filtername):
    """returns set of filtered revision for this filter name"""
    if filtername not in repo.filteredrevcache:
        func = filtertable[filtername]
        repo.filteredrevcache[filtername] = func(repo.unfiltered())
    return repo.filteredrevcache[filtername]

class repoview(object):
    """Provide a read/write view of a repo through a filtered changelog

    This object is used to access a filtered version of a repository without
    altering the original repository object itself. We can not alter the
    original object for two main reasons:
    - It prevents the use of a repo with multiple filters at the same time. In
      particular when multiple threads are involved.
    - It makes scope of the filtering harder to control.

    This object behaves very closely to the original repository. All attribute
    operations are done on the original repository:
    - An access to `repoview.someattr` actually returns `repo.someattr`,
    - A write to `repoview.someattr` actually sets value of `repo.someattr`,
    - A deletion of `repoview.someattr` actually drops `someattr`
      from `repo.__dict__`.

    The only exception is the `changelog` property. It is overridden to return
    a (surface) copy of `repo.changelog` with some revisions filtered. The
    `filtername` attribute of the view control the revisions that need to be
    filtered.  (the fact the changelog is copied is an implementation detail).

    Unlike attributes, this object intercepts all method calls. This means that
    all methods are run on the `repoview` object with the filtered `changelog`
    property. For this purpose the simple `repoview` class must be mixed with
    the actual class of the repository. This ensures that the resulting
    `repoview` object have the very same methods than the repo object. This
    leads to the property below.

        repoview.method() --> repo.__class__.method(repoview)

    The inheritance has to be done dynamically because `repo` can be of any
    subclasses of `localrepo`. Eg: `bundlerepo` or `statichttprepo`.
    """

    def __init__(self, repo, filtername):
        object.__setattr__(self, '_unfilteredrepo', repo)
        object.__setattr__(self, 'filtername', filtername)
        object.__setattr__(self, '_clcachekey', None)
        object.__setattr__(self, '_clcache', None)

    # not a propertycache on purpose we shall implement a proper cache later
    @property
    def changelog(self):
        """return a filtered version of the changeset

        this changelog must not be used for writing"""
        # some cache may be implemented later
        unfi = self._unfilteredrepo
        unfichangelog = unfi.changelog
        revs = filterrevs(unfi, self.filtername)
        cl = self._clcache
        newkey = (len(unfichangelog), unfichangelog.tip(), hash(revs))
        if cl is not None:
            # we need to check curkey too for some obscure reason.
            # MQ test show a corruption of the underlying repo (in _clcache)
            # without change in the cachekey.
            oldfilter = cl.filteredrevs
            try:
                cl.filteredrevs = ()  # disable filtering for tip
                curkey = (len(cl), cl.tip(), hash(oldfilter))
            finally:
                cl.filteredrevs = oldfilter
            if newkey != self._clcachekey or newkey != curkey:
                cl = None
        # could have been made None by the previous if
        if cl is None:
            cl = copy.copy(unfichangelog)
            cl.filteredrevs = revs
            object.__setattr__(self, '_clcache', cl)
            object.__setattr__(self, '_clcachekey', newkey)
        return cl

    def unfiltered(self):
        """Return an unfiltered version of a repo"""
        return self._unfilteredrepo

    def filtered(self, name):
        """Return a filtered version of a repository"""
        if name == self.filtername:
            return self
        return self.unfiltered().filtered(name)

    # everything access are forwarded to the proxied repo
    def __getattr__(self, attr):
        return getattr(self._unfilteredrepo, attr)

    def __setattr__(self, attr, value):
        return setattr(self._unfilteredrepo, attr, value)

    def __delattr__(self, attr):
        return delattr(self._unfilteredrepo, attr)

    # The `requirements` attribute is initialized during __init__. But
    # __getattr__ won't be called as it also exists on the class. We need
    # explicit forwarding to main repo here
    @property
    def requirements(self):
        return self._unfilteredrepo.requirements