view mercurial/txnutil.py @ 45034:b1a1702262c9 stable

py3: fix crash when server address is 0.0.0.0 (issue6362)

`socket.getfqdn()` assumes that the name is passed as `str` on Python 3 and
always returns `str` in this case. Mercurial passed `bytes` (but still expected
a `str` result), which worked by chance in many cases, except for e.g.
b'0.0.0.0', which was returned unchanged, breaking later code.

Instead of calling `socket.getfqdn()`, we can also use `self.server_name` from
the base `HTTPServer` class, which already stores the FQDN of the locally-bound
socket name (see `BaseHTTPServer.py` in the Python 2 stdlib and
`http/server.py` in the Python 3 stdlib).

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# 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

import errno

from . import encoding


def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get(b'HG_PENDING')


def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)