view mercurial/txnutil.py @ 43617:697c2e32c490

packaging: ship all help .txt files on WiX

These are technically not needed. But it is easier to ship
all files than to cherry-pick. A `make install` will copy
these files, so the new behavior is consistent with that.
This also makes WiX consistent with Inno, which is my main
reason for doing this.

If we don't want to ship the files (which is a valid argument),
I think we can do that in a follow up.

Differential Revision: https://phab.mercurial-scm.org/D7166

# 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)