1 """

     2 changegroup.py - Mercurial changegroup manipulation functions

     3 

     4  Copyright 2006 Matt Mackall <mpm@selenic.com>

     5 

     6 This software may be used and distributed according to the terms

     7 of the GNU General Public License, incorporated herein by reference.

     8 """

     9 import struct

    10 from demandload import *

    11 demandload(globals(), "util")

    12 

    13 def getchunk(source):

    14     """get a chunk from a changegroup"""

    15     d = source.read(4)

    16     if not d:

    17         return ""

    18     l = struct.unpack(">l", d)[0]

    19     if l <= 4:

    20         return ""

    21     d = source.read(l - 4)

    22     if len(d) < l - 4:

    23         raise util.Abort(_("premature EOF reading chunk"

    24                            " (got %d bytes, expected %d)")

    25                           % (len(d), l - 4))

    26     return d

    27 

    28 def chunkiter(source):

    29     """iterate through the chunks in source"""

    30     while 1:

    31         c = getchunk(source)

    32         if not c:

    33             break

    34         yield c

    35 

    36 def genchunk(data):

    37     """build a changegroup chunk"""

    38     header = struct.pack(">l", len(data)+ 4)

    39     return "%s%s" % (header, data)

    40 

    41 def closechunk():

    42     return struct.pack(">l", 0)

    43