view mercurial/txnutil.py @ 33611:a2b55ee62803 stable

tests: make pdiff return appropriate exit code at comparison of files

Before this patch, pdiff script returns 0, even if diff is detected.

This issue doesn't cause failure of tests using it, if it is invoked
via extdiff extension, because extdiff itself examines changes between
specified revisions and decides exit code.

BTW, this patch ignores recursive comparison case, because:

  - there is no portable way for current while-read based
    implementation to return 1 at detecting changes

  - it isn't yet needed to replace direct "diff -r" invocation by
    pdiff for portability

# 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('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('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)