view tests/dumbhttp.py @ 31210:e1d035905b2e

similar: compare between actual file contents for exact identity

Before this patch, similarity detection logic (for addremove and
automv) depends entirely on SHA-1 digesting. But this causes incorrect
rename detection, if:

  - removing file A and adding file B occur at same committing, and
  - SHA-1 hash values of file A and B are same

This may prevent security experts from managing sample files for
SHAttered issue in Mercurial repository, for example.

  https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html
  https://shattered.it/

Hash collision itself isn't so serious for core repository
functionality of Mercurial, described by mpm as below, though.

  https://www.mercurial-scm.org/wiki/mpm/SHA1

This patch compares between actual file contents after hash comparison
for exact identity.

Even after this patch, SHA-1 is still used, because it is reasonable
enough to quickly detect existence of "(almost) same" file.

  - replacing SHA-1 causes decreasing performance, and
  - replacement of it has ambiguity, yet

Getting content of removed file (= rfctx.data()) at each exact
comparison should be cheap enough, even though getting content of
added one costs much.

  ======= ============== =====================
  file    fctx           data() reads from
  ======= ============== =====================
  removed filectx        in-memory revlog data
  added   workingfilectx storage
  ======= ============== =====================

#!/usr/bin/env python

from __future__ import absolute_import

"""
Small and dumb HTTP server for use in tests.
"""

import optparse
import os
import signal
import socket
import sys

from mercurial import (
    server,
    util,
)

httpserver = util.httpserver
OptionParser = optparse.OptionParser

if os.environ.get('HGIPV6', '0') == '1':
    class simplehttpserver(httpserver.httpserver):
        address_family = socket.AF_INET6
else:
    simplehttpserver = httpserver.httpserver

class simplehttpservice(object):
    def __init__(self, host, port):
        self.address = (host, port)
    def init(self):
        self.httpd = simplehttpserver(
            self.address, httpserver.simplehttprequesthandler)
    def run(self):
        self.httpd.serve_forever()

if __name__ == '__main__':
    parser = OptionParser()
    parser.add_option('-p', '--port', dest='port', type='int', default=8000,
        help='TCP port to listen on', metavar='PORT')
    parser.add_option('-H', '--host', dest='host', default='localhost',
        help='hostname or IP to listen on', metavar='HOST')
    parser.add_option('--pid', dest='pid',
        help='file name where the PID of the server is stored')
    parser.add_option('-f', '--foreground', dest='foreground',
        action='store_true',
        help='do not start the HTTP server in the background')
    parser.add_option('--daemon-postexec', action='append')

    (options, args) = parser.parse_args()

    signal.signal(signal.SIGTERM, lambda x, y: sys.exit(0))

    if options.foreground and options.pid:
        parser.error("options --pid and --foreground are mutually exclusive")

    opts = {'pid_file': options.pid,
            'daemon': not options.foreground,
            'daemon_postexec': options.daemon_postexec}
    service = simplehttpservice(options.host, options.port)
    server.runservice(opts, initfn=service.init, runfn=service.run,
                      runargs=[sys.executable, __file__] + sys.argv[1:])