hgext/interhg.py

lock: fixed race condition in trylock/testlock (issue3506)

Suppose the following scenario:

1. Process A takes the lock (e.g. on commit).
2. Process B wants to grab the lock. Since lock file exists
   the exception is raised. In the catch block the testlock
   function is called.
3. Process A releases the lock.
4. Process B tries to read the lock file as a part of testlock
   function. This results in OSError (ENOENT) and since we're
   not inside the exception handler function this is propagated
   and aborts the whole operation.

To fix this we now check in testlock function whether lock file
actually exists and if not (i.e. if readlock fails) we just return.

# interhg.py - interhg
#
# Copyright 2007 OHASHI Hideya <[e-mail]>
#
# Contributor(s):
#   Edward Lee <[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.

'''expand expressions into changelog and summaries

This extension allows the use of a special syntax in summaries, which
will be automatically expanded into links or any other arbitrary
expression, much like InterWiki does.

A few example patterns (link to bug tracking, etc.) that may be used
in your hgrc::

  [interhg]
  issues = s!issue(\\d+)!<a href="http://bts/issue\\1">issue\\1</a>!
  bugzilla = s!((?:bug|b=|(?=#?\\d{4,}))(?:\\s*#?)(\\d+))!<a..=\\2">\\1</a>!i
  boldify = s!(^|\\s)#(\\d+)\\b! <b>#\\2</b>!
'''

import re
from mercurial.hgweb import hgweb_mod
from mercurial import templatefilters, extensions
from mercurial.i18n import _

testedwith = 'internal'

interhg_table = []

def uisetup(ui):
    orig_escape = templatefilters.filters["escape"]

    def interhg_escape(x):
        escstr = orig_escape(x)
        for regexp, format in interhg_table:
            escstr = regexp.sub(format, escstr)
        return escstr

    templatefilters.filters["escape"] = interhg_escape

def interhg_refresh(orig, self, *args, **kwargs):
    interhg_table[:] = []
    for key, pattern in self.repo.ui.configitems('interhg'):
        # grab the delimiter from the character after the "s"
        unesc = pattern[1]
        delim = re.escape(unesc)

        # identify portions of the pattern, taking care to avoid escaped
        # delimiters. the replace format and flags are optional, but delimiters
        # are required.
        match = re.match(r'^s%s(.+)(?:(?<=\\\\)|(?<!\\))%s(.*)%s([ilmsux])*$'
                         % (delim, delim, delim), pattern)
        if not match:
            self.repo.ui.warn(_("interhg: invalid pattern for %s: %s\n")
                              % (key, pattern))
            continue

        # we need to unescape the delimiter for regexp and format
        delim_re = re.compile(r'(?<!\\)\\%s' % delim)
        regexp = delim_re.sub(unesc, match.group(1))
        format = delim_re.sub(unesc, match.group(2))

        # the pattern allows for 6 regexp flags, so set them if necessary
        flagin = match.group(3)
        flags = 0
        if flagin:
            for flag in flagin.upper():
                flags |= re.__dict__[flag]

        try:
            regexp = re.compile(regexp, flags)
            interhg_table.append((regexp, format))
        except re.error:
            self.repo.ui.warn(_("interhg: invalid regexp for %s: %s\n")
                              % (key, regexp))
    return orig(self, *args, **kwargs)

extensions.wrapfunction(hgweb_mod.hgweb, 'refresh', interhg_refresh)