httppeer: move a variable to avoid a bad reference before assignment warning

No actual bug here, because the conditional used to assign is the same as the
conditional in the `finally` block that guards the reference.

mercurial/httppeer.py

@@ -1,668 +1,669
 # httppeer.py - HTTP repository proxy classes for mercurial
 #
 # Copyright 2005, 2006 Olivia Mackall <[e-mail]>
 # Copyright 2006 Vadim Gelfer <[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
 import io
 import os
 import socket
 import struct
 
 from concurrent import futures
 from .i18n import _
 from . import (
     bundle2,
     error,
     httpconnection,
     pycompat,
     statichttprepo,
     url as urlmod,
     util,
     wireprotov1peer,
 )
 from .utils import urlutil
 
 httplib = util.httplib
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 
 def encodevalueinheaders(value, header, limit):
     """Encode a string value into multiple HTTP headers.
 
     ``value`` will be encoded into 1 or more HTTP headers with the names
     ``header-<N>`` where ``<N>`` is an integer starting at 1. Each header
     name + value will be at most ``limit`` bytes long.
 
     Returns an iterable of 2-tuples consisting of header names and
     values as native strings.
     """
     # HTTP Headers are ASCII. Python 3 requires them to be unicodes,
     # not bytes. This function always takes bytes in as arguments.
     fmt = pycompat.strurl(header) + r'-%s'
     # Note: it is *NOT* a bug that the last bit here is a bytestring
     # and not a unicode: we're just getting the encoded length anyway,
     # and using an r-string to make it portable between Python 2 and 3
     # doesn't work because then the \r is a literal backslash-r
     # instead of a carriage return.
     valuelen = limit - len(fmt % '000') - len(b': \r\n')
     result = []
 
     n = 0
     for i in range(0, len(value), valuelen):
         n += 1
         result.append((fmt % str(n), pycompat.strurl(value[i : i + valuelen])))
 
     return result
 
 
 class _multifile:
     def __init__(self, *fileobjs):
         for f in fileobjs:
             if not hasattr(f, 'length'):
                 raise ValueError(
                     b'_multifile only supports file objects that '
                     b'have a length but this one does not:',
                     type(f),
                     f,
                 )
         self._fileobjs = fileobjs
         self._index = 0
 
     @property
     def length(self):
         return sum(f.length for f in self._fileobjs)
 
     def read(self, amt=None):
         if amt <= 0:
             return b''.join(f.read() for f in self._fileobjs)
         parts = []
         while amt and self._index < len(self._fileobjs):
             parts.append(self._fileobjs[self._index].read(amt))
             got = len(parts[-1])
             if got < amt:
                 self._index += 1
             amt -= got
         return b''.join(parts)
 
     def seek(self, offset, whence=os.SEEK_SET):
         if whence != os.SEEK_SET:
             raise NotImplementedError(
                 b'_multifile does not support anything other'
                 b' than os.SEEK_SET for whence on seek()'
             )
         if offset != 0:
             raise NotImplementedError(
                 b'_multifile only supports seeking to start, but that '
                 b'could be fixed if you need it'
             )
         for f in self._fileobjs:
             f.seek(0)
         self._index = 0
 
 
 def makev1commandrequest(
     ui,
     requestbuilder,
     caps,
     capablefn,
     repobaseurl,
     cmd,
     args,
     remotehidden=False,
 ):
     """Make an HTTP request to run a command for a version 1 client.
 
     ``caps`` is a set of known server capabilities. The value may be
     None if capabilities are not yet known.
 
     ``capablefn`` is a function to evaluate a capability.
 
     ``cmd``, ``args``, and ``data`` define the command, its arguments, and
     raw data to pass to it.
     """
     if cmd == b'pushkey':
         args[b'data'] = b''
     data = args.pop(b'data', None)
     headers = args.pop(b'headers', {})
 
     ui.debug(b"sending %s command\n" % cmd)
     q = [(b'cmd', cmd)]
     if remotehidden:
         q.append(('access-hidden', '1'))
     headersize = 0
     # Important: don't use self.capable() here or else you end up
     # with infinite recursion when trying to look up capabilities
     # for the first time.
     postargsok = caps is not None and b'httppostargs' in caps
 
     # Send arguments via POST.
     if postargsok and args:
         strargs = urlreq.urlencode(sorted(args.items()))
         if not data:
             data = strargs
         else:
             if isinstance(data, bytes):
                 i = io.BytesIO(data)
                 i.length = len(data)
                 data = i
             argsio = io.BytesIO(strargs)
             argsio.length = len(strargs)
             data = _multifile(argsio, data)
         headers['X-HgArgs-Post'] = len(strargs)
     elif args:
         # Calling self.capable() can infinite loop if we are calling
         # "capabilities". But that command should never accept wire
         # protocol arguments. So this should never happen.
         assert cmd != b'capabilities'
         httpheader = capablefn(b'httpheader')
         if httpheader:
             headersize = int(httpheader.split(b',', 1)[0])
 
         # Send arguments via HTTP headers.
         if headersize > 0:
             # The headers can typically carry more data than the URL.
             encoded_args = urlreq.urlencode(sorted(args.items()))
             for header, value in encodevalueinheaders(
                 encoded_args, b'X-HgArg', headersize
             ):
                 headers[header] = value
         # Send arguments via query string (Mercurial <1.9).
         else:
             q += sorted(args.items())
 
     qs = b'?%s' % urlreq.urlencode(q)
     cu = b"%s%s" % (repobaseurl, qs)
     size = 0
     if hasattr(data, 'length'):
         size = data.length
     elif data is not None:
         size = len(data)
     if data is not None and 'Content-Type' not in headers:
         headers['Content-Type'] = 'application/mercurial-0.1'
 
     # Tell the server we accept application/mercurial-0.2 and multiple
     # compression formats if the server is capable of emitting those
     # payloads.
     # Note: Keep this set empty by default, as client advertisement of
     # protocol parameters should only occur after the handshake.
     protoparams = set()
 
     mediatypes = set()
     if caps is not None:
         mt = capablefn(b'httpmediatype')
         if mt:
             protoparams.add(b'0.1')
             mediatypes = set(mt.split(b','))
 
         protoparams.add(b'partial-pull')
 
     if b'0.2tx' in mediatypes:
         protoparams.add(b'0.2')
 
     if b'0.2tx' in mediatypes and capablefn(b'compression'):
         # We /could/ compare supported compression formats and prune
         # non-mutually supported or error if nothing is mutually supported.
         # For now, send the full list to the server and have it error.
         comps = [
             e.wireprotosupport().name
             for e in util.compengines.supportedwireengines(util.CLIENTROLE)
         ]
         protoparams.add(b'comp=%s' % b','.join(comps))
 
     if protoparams:
         protoheaders = encodevalueinheaders(
             b' '.join(sorted(protoparams)), b'X-HgProto', headersize or 1024
         )
         for header, value in protoheaders:
             headers[header] = value
 
     varyheaders = []
     for header in headers:
         if header.lower().startswith('x-hg'):
             varyheaders.append(header)
 
     if varyheaders:
         headers['Vary'] = ','.join(sorted(varyheaders))
 
     req = requestbuilder(pycompat.strurl(cu), data, headers)
 
     if data is not None:
         ui.debug(b"sending %d bytes\n" % size)
         req.add_unredirected_header('Content-Length', '%d' % size)
 
     return req, cu, qs
 
 
 def sendrequest(ui, opener, req):
     """Send a prepared HTTP request.
 
     Returns the response object.
     """
     dbg = ui.debug
+    line = b'devel-peer-request: %s\n'
+
     if ui.debugflag and ui.configbool(b'devel', b'debug.peer-request'):
-        line = b'devel-peer-request: %s\n'
         dbg(
             line
             % b'%s %s'
             % (
                 pycompat.bytesurl(req.get_method()),
                 pycompat.bytesurl(req.get_full_url()),
             )
         )
         hgargssize = None
 
         for header, value in sorted(req.header_items()):
             header = pycompat.bytesurl(header)
             value = pycompat.bytesurl(value)
             if header.startswith(b'X-hgarg-'):
                 if hgargssize is None:
                     hgargssize = 0
                 hgargssize += len(value)
             else:
                 dbg(line % b'  %s %s' % (header, value))
 
         if hgargssize is not None:
             dbg(
                 line
                 % b'  %d bytes of commands arguments in headers'
                 % hgargssize
             )
         data = req.data
         if data is not None:
             length = getattr(data, 'length', None)
             if length is None:
                 length = len(data)
             dbg(line % b'  %d bytes of data' % length)
 
         start = util.timer()
 
     res = None
     try:
         res = opener.open(req)
     except urlerr.httperror as inst:
         if inst.code == 401:
             raise error.Abort(_(b'authorization failed'))
         raise
     except httplib.HTTPException as inst:
         ui.debug(
             b'http error requesting %s\n'
             % urlutil.hidepassword(req.get_full_url())
         )
         ui.traceback()
         raise IOError(None, inst)
     finally:
         if ui.debugflag and ui.configbool(b'devel', b'debug.peer-request'):
             code = res.code if res else -1
             dbg(
                 line
                 % b'  finished in %.4f seconds (%d)'
                 % (util.timer() - start, code)
             )
 
     # Insert error handlers for common I/O failures.
     urlmod.wrapresponse(res)
 
     return res
 
 
 class RedirectedRepoError(error.RepoError):
     def __init__(self, msg, respurl):
         super(RedirectedRepoError, self).__init__(msg)
         self.respurl = respurl
 
 
 def parsev1commandresponse(ui, baseurl, requrl, qs, resp, compressible):
     # record the url we got redirected to
     redirected = False
     respurl = pycompat.bytesurl(resp.geturl())
     if respurl.endswith(qs):
         respurl = respurl[: -len(qs)]
         qsdropped = False
     else:
         qsdropped = True
 
     if baseurl.rstrip(b'/') != respurl.rstrip(b'/'):
         redirected = True
         if not ui.quiet:
             ui.warn(_(b'real URL is %s\n') % respurl)
 
     try:
         proto = pycompat.bytesurl(resp.getheader('content-type', ''))
     except AttributeError:
         proto = pycompat.bytesurl(resp.headers.get('content-type', ''))
 
     safeurl = urlutil.hidepassword(baseurl)
     if proto.startswith(b'application/hg-error'):
         raise error.OutOfBandError(resp.read())
 
     # Pre 1.0 versions of Mercurial used text/plain and
     # application/hg-changegroup. We don't support such old servers.
     if not proto.startswith(b'application/mercurial-'):
         ui.debug(b"requested URL: '%s'\n" % urlutil.hidepassword(requrl))
         msg = _(
             b"'%s' does not appear to be an hg repository:\n"
             b"---%%<--- (%s)\n%s\n---%%<---\n"
         ) % (safeurl, proto or b'no content-type', resp.read(1024))
 
         # Some servers may strip the query string from the redirect. We
         # raise a special error type so callers can react to this specially.
         if redirected and qsdropped:
             raise RedirectedRepoError(msg, respurl)
         else:
             raise error.RepoError(msg)
 
     try:
         subtype = proto.split(b'-', 1)[1]
 
         version_info = tuple([int(n) for n in subtype.split(b'.')])
     except ValueError:
         raise error.RepoError(
             _(b"'%s' sent a broken Content-Type header (%s)") % (safeurl, proto)
         )
 
     # TODO consider switching to a decompression reader that uses
     # generators.
     if version_info == (0, 1):
         if compressible:
             resp = util.compengines[b'zlib'].decompressorreader(resp)
 
     elif version_info == (0, 2):
         # application/mercurial-0.2 always identifies the compression
         # engine in the payload header.
         elen = struct.unpack(b'B', util.readexactly(resp, 1))[0]
         ename = util.readexactly(resp, elen)
         engine = util.compengines.forwiretype(ename)
 
         resp = engine.decompressorreader(resp)
     else:
         raise error.RepoError(
             _(b"'%s' uses newer protocol %s") % (safeurl, subtype)
         )
 
     return respurl, proto, resp
 
 
 class httppeer(wireprotov1peer.wirepeer):
     def __init__(
         self, ui, path, url, opener, requestbuilder, caps, remotehidden=False
     ):
         super().__init__(ui, path=path, remotehidden=remotehidden)
         self._url = url
         self._caps = caps
         self.limitedarguments = caps is not None and b'httppostargs' not in caps
         self._urlopener = opener
         self._requestbuilder = requestbuilder
         self._remotehidden = remotehidden
 
     def __del__(self):
         for h in self._urlopener.handlers:
             h.close()
             getattr(h, "close_all", lambda: None)()
 
     # Begin of ipeerconnection interface.
 
     def url(self):
         return self.path.loc
 
     def local(self):
         return None
 
     def canpush(self):
         return True
 
     def close(self):
         try:
             reqs, sent, recv = (
                 self._urlopener.requestscount,
                 self._urlopener.sentbytescount,
                 self._urlopener.receivedbytescount,
             )
         except AttributeError:
             return
         self.ui.note(
             _(
                 b'(sent %d HTTP requests and %d bytes; '
                 b'received %d bytes in responses)\n'
             )
             % (reqs, sent, recv)
         )
 
     # End of ipeerconnection interface.
 
     # Begin of ipeercommands interface.
 
     def capabilities(self):
         return self._caps
 
     def _finish_inline_clone_bundle(self, stream):
         # HTTP streams must hit the end to process the last empty
         # chunk of Chunked-Encoding so the connection can be reused.
         chunk = stream.read(1)
         if chunk:
             self._abort(error.ResponseError(_(b"unexpected response:"), chunk))
 
     # End of ipeercommands interface.
 
     def _callstream(self, cmd, _compressible=False, **args):
         args = pycompat.byteskwargs(args)
 
         req, cu, qs = makev1commandrequest(
             self.ui,
             self._requestbuilder,
             self._caps,
             self.capable,
             self._url,
             cmd,
             args,
             self._remotehidden,
         )
 
         resp = sendrequest(self.ui, self._urlopener, req)
 
         self._url, ct, resp = parsev1commandresponse(
             self.ui, self._url, cu, qs, resp, _compressible
         )
 
         return resp
 
     def _call(self, cmd, **args):
         fp = self._callstream(cmd, **args)
         try:
             return fp.read()
         finally:
             # if using keepalive, allow connection to be reused
             fp.close()
 
     def _callpush(self, cmd, cg, **args):
         # have to stream bundle to a temp file because we do not have
         # http 1.1 chunked transfer.
 
         types = self.capable(b'unbundle')
         try:
             types = types.split(b',')
         except AttributeError:
             # servers older than d1b16a746db6 will send 'unbundle' as a
             # boolean capability. They only support headerless/uncompressed
             # bundles.
             types = [b""]
         for x in types:
             if x in bundle2.bundletypes:
                 type = x
                 break
 
         tempname = bundle2.writebundle(self.ui, cg, None, type)
         fp = httpconnection.httpsendfile(self.ui, tempname, b"rb")
         headers = {'Content-Type': 'application/mercurial-0.1'}
 
         try:
             r = self._call(cmd, data=fp, headers=headers, **args)
             vals = r.split(b'\n', 1)
             if len(vals) < 2:
                 raise error.ResponseError(_(b"unexpected response:"), r)
             return vals
         except urlerr.httperror:
             # Catch and re-raise these so we don't try and treat them
             # like generic socket errors. They lack any values in
             # .args on Python 3 which breaks our socket.error block.
             raise
         except socket.error as err:
             if err.args[0] in (errno.ECONNRESET, errno.EPIPE):
                 raise error.Abort(_(b'push failed: %s') % err.args[1])
             raise error.Abort(err.args[1])
         finally:
             fp.close()
             os.unlink(tempname)
 
     def _calltwowaystream(self, cmd, fp, **args):
         # dump bundle to disk
         fd, filename = pycompat.mkstemp(prefix=b"hg-bundle-", suffix=b".hg")
         try:
             with os.fdopen(fd, "wb") as fh:
                 d = fp.read(4096)
                 while d:
                     fh.write(d)
                     d = fp.read(4096)
             # start http push
             with httpconnection.httpsendfile(self.ui, filename, b"rb") as fp_:
                 headers = {'Content-Type': 'application/mercurial-0.1'}
                 return self._callstream(cmd, data=fp_, headers=headers, **args)
         finally:
             os.unlink(filename)
 
     def _callcompressable(self, cmd, **args):
         return self._callstream(cmd, _compressible=True, **args)
 
     def _abort(self, exception):
         raise exception
 
 
 class queuedcommandfuture(futures.Future):
     """Wraps result() on command futures to trigger submission on call."""
 
     def result(self, timeout=None):
         if self.done():
             return futures.Future.result(self, timeout)
 
         self._peerexecutor.sendcommands()
 
         # sendcommands() will restore the original __class__ and self.result
         # will resolve to Future.result.
         return self.result(timeout)
 
 
 def performhandshake(ui, url, opener, requestbuilder):
     # The handshake is a request to the capabilities command.
 
     caps = None
 
     def capable(x):
         raise error.ProgrammingError(b'should not be called')
 
     args = {}
 
     req, requrl, qs = makev1commandrequest(
         ui, requestbuilder, caps, capable, url, b'capabilities', args
     )
     resp = sendrequest(ui, opener, req)
 
     # The server may redirect us to the repo root, stripping the
     # ?cmd=capabilities query string from the URL. The server would likely
     # return HTML in this case and ``parsev1commandresponse()`` would raise.
     # We catch this special case and re-issue the capabilities request against
     # the new URL.
     #
     # We should ideally not do this, as a redirect that drops the query
     # string from the URL is arguably a server bug. (Garbage in, garbage out).
     # However,  Mercurial clients for several years appeared to handle this
     # issue without behavior degradation. And according to issue 5860, it may
     # be a longstanding bug in some server implementations. So we allow a
     # redirect that drops the query string to "just work."
     try:
         respurl, ct, resp = parsev1commandresponse(
             ui, url, requrl, qs, resp, compressible=False
         )
     except RedirectedRepoError as e:
         req, requrl, qs = makev1commandrequest(
             ui, requestbuilder, caps, capable, e.respurl, b'capabilities', args
         )
         resp = sendrequest(ui, opener, req)
         respurl, ct, resp = parsev1commandresponse(
             ui, url, requrl, qs, resp, compressible=False
         )
 
     try:
         rawdata = resp.read()
     finally:
         resp.close()
 
     if not ct.startswith(b'application/mercurial-'):
         raise error.ProgrammingError(b'unexpected content-type: %s' % ct)
 
     info = {b'v1capabilities': set(rawdata.split())}
 
     return respurl, info
 
 
 def _make_peer(
     ui, path, opener=None, requestbuilder=urlreq.request, remotehidden=False
 ):
     """Construct an appropriate HTTP peer instance.
 
     ``opener`` is an ``url.opener`` that should be used to establish
     connections, perform HTTP requests.
 
     ``requestbuilder`` is the type used for constructing HTTP requests.
     It exists as an argument so extensions can override the default.
     """
     if path.url.query or path.url.fragment:
         msg = _(b'unsupported URL component: "%s"')
         msg %= path.url.query or path.url.fragment
         raise error.Abort(msg)
 
     # urllib cannot handle URLs with embedded user or passwd.
     url, authinfo = path.url.authinfo()
     ui.debug(b'using %s\n' % url)
 
     opener = opener or urlmod.opener(ui, authinfo)
 
     respurl, info = performhandshake(ui, url, opener, requestbuilder)
 
     return httppeer(
         ui,
         path,
         respurl,
         opener,
         requestbuilder,
         info[b'v1capabilities'],
         remotehidden=remotehidden,
     )
 
 
 def make_peer(
     ui, path, create, intents=None, createopts=None, remotehidden=False
 ):
     if create:
         raise error.Abort(_(b'cannot create new http repository'))
     try:
         if path.url.scheme == b'https' and not urlmod.has_https:
             raise error.Abort(
                 _(b'Python support for SSL and HTTPS is not installed')
             )
 
         inst = _make_peer(ui, path, remotehidden=remotehidden)
 
         return inst
     except error.RepoError as httpexception:
         try:
             path = path.copy(new_raw_location=b"static-" + path.rawloc)
             r = statichttprepo.make_peer(ui, path, create)
             ui.note(_(b'(falling back to static-http)\n'))
             return r
         except error.RepoError:
             raise httpexception  # use the original http RepoError instead