mercurial/urllibcompat.py

worker: avoid potential partial write of pickled data

Previously, the code wrote the pickled data using os.write(). However,
os.write() can write less bytes than passed to it. To trigger the problem, the
pickled data had to be larger than 2147479552 bytes on my system.

Instead, open a file object and pass it to pickle.dump(). This also has the
advantage that it doesn’t buffer the whole pickled data in memory.

Note that the opened file must be buffered because pickle doesn’t support
unbuffered streams because unbuffered streams’ write() method might write less
bytes than passed to it (like os.write()) but pickle.dump() relies on that all
bytes are written (see https://github.com/python/cpython/issues/93050).

The side effect of using a file object and a with statement is that wfd is
explicitly closed now while it seems like before it was implicitly closed by
process exit.

# urllibcompat.py - adapters to ease using urllib2 on Py2 and urllib on Py3
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import http.server
import urllib.error
import urllib.parse
import urllib.request
import urllib.response

from .pycompat import getattr
from . import pycompat

_sysstr = pycompat.sysstr


class _pycompatstub:
    def __init__(self):
        self._aliases = {}

    def _registeraliases(self, origin, items):
        """Add items that will be populated at the first access"""
        items = map(_sysstr, items)
        self._aliases.update(
            (item.replace('_', '').lower(), (origin, item)) for item in items
        )

    def _registeralias(self, origin, attr, name):
        """Alias ``origin``.``attr`` as ``name``"""
        self._aliases[_sysstr(name)] = (origin, _sysstr(attr))

    def __getattr__(self, name):
        try:
            origin, item = self._aliases[name]
        except KeyError:
            raise AttributeError(name)
        self.__dict__[name] = obj = getattr(origin, item)
        return obj


httpserver = _pycompatstub()
urlreq = _pycompatstub()
urlerr = _pycompatstub()

urlreq._registeraliases(
    urllib.parse,
    (
        b"splitattr",
        b"splitpasswd",
        b"splitport",
        b"splituser",
        b"urlparse",
        b"urlunparse",
    ),
)
urlreq._registeralias(urllib.parse, b"parse_qs", b"parseqs")
urlreq._registeralias(urllib.parse, b"parse_qsl", b"parseqsl")
urlreq._registeralias(urllib.parse, b"unquote_to_bytes", b"unquote")

urlreq._registeraliases(
    urllib.request,
    (
        b"AbstractHTTPHandler",
        b"BaseHandler",
        b"build_opener",
        b"FileHandler",
        b"FTPHandler",
        b"ftpwrapper",
        b"HTTPHandler",
        b"HTTPSHandler",
        b"install_opener",
        b"pathname2url",
        b"HTTPBasicAuthHandler",
        b"HTTPDigestAuthHandler",
        b"HTTPPasswordMgrWithDefaultRealm",
        b"ProxyHandler",
        b"Request",
        b"url2pathname",
        b"urlopen",
    ),
)


urlreq._registeraliases(
    urllib.response,
    (
        b"addclosehook",
        b"addinfourl",
    ),
)

urlerr._registeraliases(
    urllib.error,
    (
        b"HTTPError",
        b"URLError",
    ),
)

httpserver._registeraliases(
    http.server,
    (
        b"HTTPServer",
        b"BaseHTTPRequestHandler",
        b"SimpleHTTPRequestHandler",
        b"CGIHTTPRequestHandler",
    ),
)

# urllib.parse.quote() accepts both str and bytes, decodes bytes
# (if necessary), and returns str. This is wonky. We provide a custom
# implementation that only accepts bytes and emits bytes.
def quote(s, safe='/'):
    # bytestr has an __iter__ that emits characters. quote_from_bytes()
    # does an iteration and expects ints. We coerce to bytes to appease it.
    if isinstance(s, pycompat.bytestr):
        s = bytes(s)
    s = urllib.parse.quote_from_bytes(s, safe=safe)
    return s.encode('ascii', 'strict')


# urllib.parse.urlencode() returns str. We use this function to make
# sure we return bytes.
def urlencode(query, doseq=False):
    s = urllib.parse.urlencode(query, doseq=doseq)
    return s.encode('ascii')


urlreq.quote = quote
urlreq.urlencode = urlencode


def getfullurl(req):
    return req.full_url


def gethost(req):
    return req.host


def getselector(req):
    return req.selector


def getdata(req):
    return req.data


def hasdata(req):
    return req.data is not None