view mercurial/changegroup.py @ 9709:5858117a0077

merge: supply base node to merge tools in the environment

Merge tools will be able to exploit this to correctly merge backouts.
This won't work fully, though, until issue 1327 is solved, since the
node information is not necessarily correct.

# 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 version 2, incorporated herein by reference.

from i18n import _
import util
import struct, os, bz2, zlib, tempfile

def getchunk(source):
    """return the next chunk from changegroup 'source' as a string"""
    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, yielding a sequence of chunks
    (strings)"""
    while 1:
        c = getchunk(source)
        if not c:
            break
        yield c

def chunkheader(length):
    """return a changegroup chunk header (string)"""
    return struct.pack(">l", length + 4)

def closechunk():
    """return a changegroup chunk header (string) for a zero-length chunk"""
    return struct.pack(">l", 0)

class nocompress(object):
    def compress(self, x):
        return x
    def flush(self):
        return ""

bundletypes = {
    "": ("", nocompress),
    "HG10UN": ("HG10UN", nocompress),
    "HG10BZ": ("HG10", lambda: bz2.BZ2Compressor()),
    "HG10GZ": ("HG10GZ", lambda: zlib.compressobj()),
}

# hgweb uses this list to communicate its preferred type
bundlepriority = ['HG10GZ', 'HG10BZ', 'HG10UN']

def writebundle(cg, filename, bundletype):
    """Write a bundle file and return its filename.

    Existing files will not be overwritten.
    If no filename is specified, a temporary file is created.
    bz2 compression can be turned off.
    The bundle file will be deleted in case of errors.
    """

    fh = None
    cleanup = None
    try:
        if filename:
            fh = open(filename, "wb")
        else:
            fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
            fh = os.fdopen(fd, "wb")
        cleanup = filename

        header, compressor = bundletypes[bundletype]
        fh.write(header)
        z = compressor()

        # parse the changegroup data, otherwise we will block
        # in case of sshrepo because we don't know the end of the stream

        # an empty chunkiter is the end of the changegroup
        # a changegroup has at least 2 chunkiters (changelog and manifest).
        # after that, an empty chunkiter is the end of the changegroup
        empty = False
        count = 0
        while not empty or count <= 2:
            empty = True
            count += 1
            for chunk in chunkiter(cg):
                empty = False
                fh.write(z.compress(chunkheader(len(chunk))))
                pos = 0
                while pos < len(chunk):
                    next = pos + 2**20
                    fh.write(z.compress(chunk[pos:next]))
                    pos = next
            fh.write(z.compress(closechunk()))
        fh.write(z.flush())
        cleanup = None
        return filename
    finally:
        if fh is not None:
            fh.close()
        if cleanup is not None:
            os.unlink(cleanup)

def unbundle(header, fh):
    if header == 'HG10UN':
        return fh
    elif not header.startswith('HG'):
        # old client with uncompressed bundle
        def generator(f):
            yield header
            for chunk in f:
                yield chunk
    elif header == 'HG10GZ':
        def generator(f):
            zd = zlib.decompressobj()
            for chunk in f:
                yield zd.decompress(chunk)
    elif header == 'HG10BZ':
        def generator(f):
            zd = bz2.BZ2Decompressor()
            zd.decompress("BZ")
            for chunk in util.filechunkiter(f, 4096):
                yield zd.decompress(chunk)
    return util.chunkbuffer(generator(fh))

def readbundle(fh, fname):
    header = fh.read(6)
    if not header.startswith('HG'):
        raise util.Abort(_('%s: not a Mercurial bundle file') % fname)
    if not header.startswith('HG10'):
        raise util.Abort(_('%s: unknown bundle version') % fname)
    elif header not in bundletypes:
        raise util.Abort(_('%s: unknown bundle compression type') % fname)
    return unbundle(header, fh)