mercurial/changegroup.py

add merge command. means same thing as "update -m".

repo.addchangegroup method now returns number of heads modified and added,
so command line can tell whether update or merge needed.  this makes
tiny change to ssh wire protocol, but change is backwards compatible.

pull command now returns 0 if no changes to pull.

"""
changegroup.py - Mercurial changegroup manipulation functions

 Copyright 2006 Matt Mackall <[e-mail]>

This software may be used and distributed according to the terms
of the GNU General Public License, incorporated herein by reference.
"""
import struct
from i18n import gettext as _
from demandload import *
demandload(globals(), "util")

def getchunk(source):
    """get a chunk from a changegroup"""
    d = source.read(4)
    if not d:
        return ""
    l = struct.unpack(">l", d)[0]
    if l <= 4:
        return ""
    d = source.read(l - 4)
    if len(d) < l - 4:
        raise util.Abort(_("premature EOF reading chunk"
                           " (got %d bytes, expected %d)")
                          % (len(d), l - 4))
    return d

def chunkiter(source):
    """iterate through the chunks in source"""
    while 1:
        c = getchunk(source)
        if not c:
            break
        yield c

def genchunk(data):
    """build a changegroup chunk"""
    header = struct.pack(">l", len(data)+ 4)
    return "%s%s" % (header, data)

def closechunk():
    return struct.pack(">l", 0)