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httppeer: detect redirect to URL without query string (issue5860)...
httppeer: detect redirect to URL without query string (issue5860) 197d10e157ce subtly changed the HTTP peer's handling of HTTP redirects. Before that changeset, we instantiated an HTTP peer instance and performed the capabilities lookup with that instance. The old code had the following relevant properties: 1) The HTTP request layer would automatically follow HTTP redirects. 2) An encountered HTTP redirect would update a peer instance variable pointing to the repo URL. 3) The peer would automagically perform a "capabilities" command request if a caller requested capabilities but capabilities were not yet defined. The first HTTP request issued by a peer is for ?cmd=capabilities. If the server responds with an HTTP redirect to a ?cmd=capabilities URL, the HTTP request layer automatically followed it, retrieved a valid capabilities response, and the peer's base URL was updated automatically so subsequent requests used the proper URL. In other words, things "just worked." In the case where the server redirected to a URL without the ?cmd=capabilities query string, the HTTP request layer would follow the redirect and likely encounter HTML. The peer's base URL would be updated and the unexpected Content-Type would raise a RepoError. We would catch RepoError and immediately call between() (testing the case for pre 0.9.1 servers not supporting the "capabilities" command). e.g. try: inst._fetchcaps() except error.RepoError: inst.between([(nullid, nullid)]) between() would eventually call into _callstream(). And _callstream() made a call to self.capable('httpheader'). capable() would call self.capabilities(), which would see that no capabilities were set (because HTML was returned for that request) and call the "capabilities" command to fetch capabilities. Because the base URL had been updated from the redirect, this 2nd "capabilities" command would succeed and the client would immediately call "between," which would also succeed. The legacy handshake succeeded. Only because "capabilities" was successfully executed as a side effect did the peer recognize that it was talking to a modern server. In other words, this all appeared to work accidentally. After 197d10e157ce, we stopped calling the "capabilities" command on the peer instance. Instead, we made the request via a low-level opener, detected the redirect as part of response handling code, and passed the redirected URL into the constructed peer instance. For cases where the redirected URL included the query string, this "just worked." But for cases where the redirected URL stripped the query string, we threw RepoError and because we removed the "between" handshake fallback, we fell through to the "is a static HTTP repo" check and performed an HTTP request for .hg/requires. While 197d10e157ce was marked as backwards incompatible, the only intended backwards incompatible behavior was not performing the "between" fallback. It was not realized that the "between" command had the side-effect of recovering from an errant redirect that dropped the query string. This commit restores the previous behavior and allows clients to handle a redirect that drops the query string. In the case where the request is redirected and the query string is dropped, we raise a special case of RepoError. We then catch this special exception in the handshake code and perform another "capabilities" request against the redirected URL. If that works, all is well. Otherwise, we fall back to the "is a static HTTP repo" check. The new code is arguably better than before 197d10e157ce, as it is explicit about the expected behavior and we avoid performing a "between" request, saving a server round trip. Differential Revision: https://phab.mercurial-scm.org/D3433

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filelog.py
267 lines | 7.5 KiB | text/x-python | PythonLexer
# filelog.py - file history class for mercurial
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# 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
from . import (
error,
repository,
revlog,
)
from .utils import (
interfaceutil,
)
@interfaceutil.implementer(repository.ifilestorage)
class filelog(object):
def __init__(self, opener, path):
self._revlog = revlog.revlog(opener,
'/'.join(('data', path + '.i')),
censorable=True)
# full name of the user visible file, relative to the repository root
self.filename = path
self.index = self._revlog.index
self.version = self._revlog.version
self.storedeltachains = self._revlog.storedeltachains
self._generaldelta = self._revlog._generaldelta
def __len__(self):
return len(self._revlog)
def __iter__(self):
return self._revlog.__iter__()
def revs(self, start=0, stop=None):
return self._revlog.revs(start=start, stop=stop)
def parents(self, node):
return self._revlog.parents(node)
def parentrevs(self, rev):
return self._revlog.parentrevs(rev)
def rev(self, node):
return self._revlog.rev(node)
def node(self, rev):
return self._revlog.node(rev)
def lookup(self, node):
return self._revlog.lookup(node)
def linkrev(self, rev):
return self._revlog.linkrev(rev)
def flags(self, rev):
return self._revlog.flags(rev)
def commonancestorsheads(self, node1, node2):
return self._revlog.commonancestorsheads(node1, node2)
def descendants(self, revs):
return self._revlog.descendants(revs)
def headrevs(self):
return self._revlog.headrevs()
def heads(self, start=None, stop=None):
return self._revlog.heads(start, stop)
def children(self, node):
return self._revlog.children(node)
def deltaparent(self, rev):
return self._revlog.deltaparent(rev)
def candelta(self, baserev, rev):
return self._revlog.candelta(baserev, rev)
def iscensored(self, rev):
return self._revlog.iscensored(rev)
def rawsize(self, rev):
return self._revlog.rawsize(rev)
def checkhash(self, text, node, p1=None, p2=None, rev=None):
return self._revlog.checkhash(text, node, p1=p1, p2=p2, rev=rev)
def revision(self, node, _df=None, raw=False):
return self._revlog.revision(node, _df=_df, raw=raw)
def revdiff(self, rev1, rev2):
return self._revlog.revdiff(rev1, rev2)
def addrevision(self, revisiondata, transaction, linkrev, p1, p2,
node=None, flags=revlog.REVIDX_DEFAULT_FLAGS,
cachedelta=None):
return self._revlog.addrevision(revisiondata, transaction, linkrev,
p1, p2, node=node, flags=flags,
cachedelta=cachedelta)
def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None):
return self._revlog.addgroup(deltas, linkmapper, transaction,
addrevisioncb=addrevisioncb)
def getstrippoint(self, minlink):
return self._revlog.getstrippoint(minlink)
def strip(self, minlink, transaction):
return self._revlog.strip(minlink, transaction)
def files(self):
return self._revlog.files()
def checksize(self):
return self._revlog.checksize()
def read(self, node):
t = self.revision(node)
if not t.startswith('\1\n'):
return t
s = t.index('\1\n', 2)
return t[s + 2:]
def add(self, text, meta, transaction, link, p1=None, p2=None):
if meta or text.startswith('\1\n'):
text = revlog.packmeta(meta, text)
return self.addrevision(text, transaction, link, p1, p2)
def renamed(self, node):
if self.parents(node)[0] != revlog.nullid:
return False
t = self.revision(node)
m = revlog.parsemeta(t)[0]
if m and "copy" in m:
return (m["copy"], revlog.bin(m["copyrev"]))
return False
def size(self, rev):
"""return the size of a given revision"""
# for revisions with renames, we have to go the slow way
node = self.node(rev)
if self.renamed(node):
return len(self.read(node))
if self.iscensored(rev):
return 0
# XXX if self.read(node).startswith("\1\n"), this returns (size+4)
return self._revlog.size(rev)
def cmp(self, node, text):
"""compare text with a given file revision
returns True if text is different than what is stored.
"""
t = text
if text.startswith('\1\n'):
t = '\1\n\1\n' + text
samehashes = not self._revlog.cmp(node, t)
if samehashes:
return False
# censored files compare against the empty file
if self.iscensored(self.rev(node)):
return text != ''
# renaming a file produces a different hash, even if the data
# remains unchanged. Check if it's the case (slow):
if self.renamed(node):
t2 = self.read(node)
return t2 != text
return True
@property
def filename(self):
return self._revlog.filename
@filename.setter
def filename(self, value):
self._revlog.filename = value
# TODO these aren't part of the interface and aren't internal methods.
# Callers should be fixed to not use them.
@property
def indexfile(self):
return self._revlog.indexfile
@indexfile.setter
def indexfile(self, value):
self._revlog.indexfile = value
@property
def datafile(self):
return self._revlog.datafile
@property
def opener(self):
return self._revlog.opener
@property
def _lazydeltabase(self):
return self._revlog._lazydeltabase
@_lazydeltabase.setter
def _lazydeltabase(self, value):
self._revlog._lazydeltabase = value
@property
def _aggressivemergedeltas(self):
return self._revlog._aggressivemergedeltas
@_aggressivemergedeltas.setter
def _aggressivemergedeltas(self, value):
self._revlog._aggressivemergedeltas = value
@property
def _inline(self):
return self._revlog._inline
@property
def _withsparseread(self):
return getattr(self._revlog, '_withsparseread', False)
@property
def _srmingapsize(self):
return self._revlog._srmingapsize
@property
def _srdensitythreshold(self):
return self._revlog._srdensitythreshold
def _deltachain(self, rev, stoprev=None):
return self._revlog._deltachain(rev, stoprev)
def chainbase(self, rev):
return self._revlog.chainbase(rev)
def chainlen(self, rev):
return self._revlog.chainlen(rev)
def clone(self, tr, destrevlog, **kwargs):
if not isinstance(destrevlog, filelog):
raise error.ProgrammingError('expected filelog to clone()')
return self._revlog.clone(tr, destrevlog._revlog, **kwargs)
def start(self, rev):
return self._revlog.start(rev)
def end(self, rev):
return self._revlog.end(rev)
def length(self, rev):
return self._revlog.length(rev)
def compress(self, data):
return self._revlog.compress(data)
def _addrevision(self, *args, **kwargs):
return self._revlog._addrevision(*args, **kwargs)