hgext/largefiles/basestore.py

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.

# Copyright 2009-2010 Gregory P. Ward
# Copyright 2009-2010 Intelerad Medical Systems Incorporated
# Copyright 2010-2011 Fog Creek Software
# Copyright 2010-2011 Unity Technologies
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''base class for store implementations and store-related utility code'''

import re

from mercurial import util, node, hg
from mercurial.i18n import _

import lfutil

class StoreError(Exception):
    '''Raised when there is a problem getting files from or putting
    files to a central store.'''
    def __init__(self, filename, hash, url, detail):
        self.filename = filename
        self.hash = hash
        self.url = url
        self.detail = detail

    def longmessage(self):
        return (_("error getting id %s from url %s for file %s: %s\n") %
                 (self.hash, util.hidepassword(self.url), self.filename,
                  self.detail))

    def __str__(self):
        return "%s: %s" % (util.hidepassword(self.url), self.detail)

class basestore(object):
    def __init__(self, ui, repo, url):
        self.ui = ui
        self.repo = repo
        self.url = url

    def put(self, source, hash):
        '''Put source file into the store so it can be retrieved by hash.'''
        raise NotImplementedError('abstract method')

    def exists(self, hashes):
        '''Check to see if the store contains the given hashes. Given an
        iterable of hashes it returns a mapping from hash to bool.'''
        raise NotImplementedError('abstract method')

    def get(self, files):
        '''Get the specified largefiles from the store and write to local
        files under repo.root.  files is a list of (filename, hash)
        tuples.  Return (success, missing), lists of files successfully
        downloaded and those not found in the store.  success is a list
        of (filename, hash) tuples; missing is a list of filenames that
        we could not get.  (The detailed error message will already have
        been presented to the user, so missing is just supplied as a
        summary.)'''
        success = []
        missing = []
        ui = self.ui

        at = 0
        available = self.exists(set(hash for (_filename, hash) in files))
        for filename, hash in files:
            ui.progress(_('getting largefiles'), at, unit='lfile',
                total=len(files))
            at += 1
            ui.note(_('getting %s:%s\n') % (filename, hash))

            if not available.get(hash):
                ui.warn(_('%s: largefile %s not available from %s\n')
                        % (filename, hash, util.hidepassword(self.url)))
                missing.append(filename)
                continue

            if self._gethash(filename, hash):
                success.append((filename, hash))
            else:
                missing.append(filename)

        ui.progress(_('getting largefiles'), None)
        return (success, missing)

    def _gethash(self, filename, hash):
        """Get file with the provided hash and store it in the local repo's
        store and in the usercache.
        filename is for informational messages only.
        """
        util.makedirs(lfutil.storepath(self.repo, ''))
        storefilename = lfutil.storepath(self.repo, hash)

        tmpname = storefilename + '.tmp'
        tmpfile = util.atomictempfile(tmpname,
                                      createmode=self.repo.store.createmode)

        try:
            gothash = self._getfile(tmpfile, filename, hash)
        except StoreError, err:
            self.ui.warn(err.longmessage())
            gothash = ""
        tmpfile.close()

        if gothash != hash:
            if gothash != "":
                self.ui.warn(_('%s: data corruption (expected %s, got %s)\n')
                             % (filename, hash, gothash))
            util.unlink(tmpname)
            return False

        util.rename(tmpname, storefilename)
        lfutil.linktousercache(self.repo, hash)
        return True

    def verify(self, revs, contents=False):
        '''Verify the existence (and, optionally, contents) of every big
        file revision referenced by every changeset in revs.
        Return 0 if all is well, non-zero on any errors.'''
        failed = False

        self.ui.status(_('searching %d changesets for largefiles\n') %
                       len(revs))
        verified = set()                # set of (filename, filenode) tuples

        for rev in revs:
            cctx = self.repo[rev]
            cset = "%d:%s" % (cctx.rev(), node.short(cctx.node()))

            for standin in cctx:
                if self._verifyfile(cctx, cset, contents, standin, verified):
                    failed = True

        numrevs = len(verified)
        numlfiles = len(set([fname for (fname, fnode) in verified]))
        if contents:
            self.ui.status(
                _('verified contents of %d revisions of %d largefiles\n')
                % (numrevs, numlfiles))
        else:
            self.ui.status(
                _('verified existence of %d revisions of %d largefiles\n')
                % (numrevs, numlfiles))
        return int(failed)

    def _getfile(self, tmpfile, filename, hash):
        '''Fetch one revision of one file from the store and write it
        to tmpfile.  Compute the hash of the file on-the-fly as it
        downloads and return the hash.  Close tmpfile.  Raise
        StoreError if unable to download the file (e.g. it does not
        exist in the store).'''
        raise NotImplementedError('abstract method')

    def _verifyfile(self, cctx, cset, contents, standin, verified):
        '''Perform the actual verification of a file in the store.
        'cset' is only used in warnings.
        'contents' controls verification of content hash.
        'standin' is the standin path of the largefile to verify.
        'verified' is maintained as a set of already verified files.
        Returns _true_ if it is a standin and any problems are found!
        '''
        raise NotImplementedError('abstract method')

import localstore, wirestore

_storeprovider = {
    'file':  [localstore.localstore],
    'http':  [wirestore.wirestore],
    'https': [wirestore.wirestore],
    'ssh': [wirestore.wirestore],
    }

_scheme_re = re.compile(r'^([a-zA-Z0-9+-.]+)://')

# During clone this function is passed the src's ui object
# but it needs the dest's ui object so it can read out of
# the config file. Use repo.ui instead.
def _openstore(repo, remote=None, put=False):
    ui = repo.ui

    if not remote:
        lfpullsource = getattr(repo, 'lfpullsource', None)
        if lfpullsource:
            path = ui.expandpath(lfpullsource)
        else:
            path = ui.expandpath('default-push', 'default')

        # ui.expandpath() leaves 'default-push' and 'default' alone if
        # they cannot be expanded: fallback to the empty string,
        # meaning the current directory.
        if path == 'default-push' or path == 'default':
            path = ''
            remote = repo
        else:
            path, _branches = hg.parseurl(path)
            remote = hg.peer(repo, {}, path)

    # The path could be a scheme so use Mercurial's normal functionality
    # to resolve the scheme to a repository and use its path
    path = util.safehasattr(remote, 'url') and remote.url() or remote.path

    match = _scheme_re.match(path)
    if not match:                       # regular filesystem path
        scheme = 'file'
    else:
        scheme = match.group(1)

    try:
        storeproviders = _storeprovider[scheme]
    except KeyError:
        raise util.Abort(_('unsupported URL scheme %r') % scheme)

    for classobj in storeproviders:
        try:
            return classobj(ui, repo, remote)
        except lfutil.storeprotonotcapable:
            pass

    raise util.Abort(_('%s does not appear to be a largefile store') %
                     util.hidepassword(path))