tests/md5sum.py

commands.push: abort when revisions evaluate to empty set (BC)

If the "-r" argument is specified to "hg push," the user has expressed
an intent for a specific changeset to be present on the remote. If that
expression cannot be mapped to a known changeset, the user's intent is
ambiguous and cannot be acted upon without making assumptions.

Previously, if arguments to `push -r <rev>` evaluated to an empty set
(perhaps the user specified a revset that didn't evaluate to anything),
the empty "revs" list would be passed down to "exchange.push" where
it appears the empty list was being interpreted as "push everything."

This patch adds validation to the "-r" argument to the push command. If
the argument is specified but doesn't resolve to a changeset, the
command will abort instead of doing something potentially unexpected.

This patch is technically breaking backwards compatibility. I believe
this is justified because the new behavior closes a crack that could
result in undefined or under-defined behavior. Also, this patch doesn't
drop client capabilities because if users really wanted to push all
changesets, they can simply omit the "-r" argument from push completely.

#!/usr/bin/env python
#
# Based on python's Tools/scripts/md5sum.py
#
# This software may be used and distributed according to the terms
# of the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2, which is
# GPL-compatible.

import sys, os

try:
    from hashlib import md5
except ImportError:
    from md5 import md5

try:
    import msvcrt
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

for filename in sys.argv[1:]:
    try:
        fp = open(filename, 'rb')
    except IOError, msg:
        sys.stderr.write('%s: Can\'t open: %s\n' % (filename, msg))
        sys.exit(1)

    m = md5()
    try:
        while True:
            data = fp.read(8192)
            if not data:
                break
            m.update(data)
    except IOError, msg:
        sys.stderr.write('%s: I/O error: %s\n' % (filename, msg))
        sys.exit(1)
    sys.stdout.write('%s  %s\n' % (m.hexdigest(), filename))

sys.exit(0)