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# changegroup.py - Mercurial changegroup manipulation functions
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#
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# Copyright 2006 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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from i18n import _
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from node import nullrev
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import mdiff, util
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import struct, os, bz2, zlib, tempfile
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_BUNDLE10_DELTA_HEADER = "20s20s20s20s"
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def readexactly(stream, n):
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'''read n bytes from stream.read and abort if less was available'''
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s = stream.read(n)
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if len(s) < n:
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raise util.Abort(_("stream ended unexpectedly"
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" (got %d bytes, expected %d)")
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% (len(s), n))
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return s
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def getchunk(stream):
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"""return the next chunk from stream as a string"""
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d = readexactly(stream, 4)
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l = struct.unpack(">l", d)[0]
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if l <= 4:
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if l:
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raise util.Abort(_("invalid chunk length %d") % l)
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return ""
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return readexactly(stream, l - 4)
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def chunkheader(length):
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"""return a changegroup chunk header (string)"""
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return struct.pack(">l", length + 4)
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def closechunk():
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"""return a changegroup chunk header (string) for a zero-length chunk"""
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return struct.pack(">l", 0)
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class nocompress(object):
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def compress(self, x):
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return x
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def flush(self):
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return ""
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bundletypes = {
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"": ("", nocompress), # only when using unbundle on ssh and old http servers
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# since the unification ssh accepts a header but there
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# is no capability signaling it.
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"HG10UN": ("HG10UN", nocompress),
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"HG10BZ": ("HG10", lambda: bz2.BZ2Compressor()),
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"HG10GZ": ("HG10GZ", lambda: zlib.compressobj()),
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}
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# hgweb uses this list to communicate its preferred type
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bundlepriority = ['HG10GZ', 'HG10BZ', 'HG10UN']
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def writebundle(cg, filename, bundletype):
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"""Write a bundle file and return its filename.
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Existing files will not be overwritten.
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If no filename is specified, a temporary file is created.
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bz2 compression can be turned off.
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The bundle file will be deleted in case of errors.
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"""
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fh = None
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cleanup = None
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try:
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if filename:
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fh = open(filename, "wb")
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else:
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fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
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fh = os.fdopen(fd, "wb")
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cleanup = filename
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header, compressor = bundletypes[bundletype]
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fh.write(header)
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z = compressor()
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# parse the changegroup data, otherwise we will block
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# in case of sshrepo because we don't know the end of the stream
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# an empty chunkgroup is the end of the changegroup
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# a changegroup has at least 2 chunkgroups (changelog and manifest).
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# after that, an empty chunkgroup is the end of the changegroup
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empty = False
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count = 0
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while not empty or count <= 2:
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empty = True
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count += 1
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while True:
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chunk = getchunk(cg)
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if not chunk:
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break
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empty = False
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fh.write(z.compress(chunkheader(len(chunk))))
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pos = 0
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while pos < len(chunk):
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next = pos + 2**20
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fh.write(z.compress(chunk[pos:next]))
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pos = next
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fh.write(z.compress(closechunk()))
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fh.write(z.flush())
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cleanup = None
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return filename
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finally:
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if fh is not None:
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fh.close()
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if cleanup is not None:
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os.unlink(cleanup)
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def decompressor(fh, alg):
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if alg == 'UN':
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return fh
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elif alg == 'GZ':
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def generator(f):
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zd = zlib.decompressobj()
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for chunk in f:
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yield zd.decompress(chunk)
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elif alg == 'BZ':
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def generator(f):
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zd = bz2.BZ2Decompressor()
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zd.decompress("BZ")
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for chunk in util.filechunkiter(f, 4096):
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yield zd.decompress(chunk)
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else:
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raise util.Abort("unknown bundle compression '%s'" % alg)
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return util.chunkbuffer(generator(fh))
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class unbundle10(object):
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deltaheader = _BUNDLE10_DELTA_HEADER
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deltaheadersize = struct.calcsize(deltaheader)
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def __init__(self, fh, alg):
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self._stream = decompressor(fh, alg)
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self._type = alg
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self.callback = None
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def compressed(self):
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return self._type != 'UN'
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def read(self, l):
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return self._stream.read(l)
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def seek(self, pos):
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return self._stream.seek(pos)
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def tell(self):
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return self._stream.tell()
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def close(self):
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return self._stream.close()
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def chunklength(self):
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d = readexactly(self._stream, 4)
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l = struct.unpack(">l", d)[0]
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if l <= 4:
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if l:
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raise util.Abort(_("invalid chunk length %d") % l)
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return 0
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if self.callback:
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self.callback()
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return l - 4
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def changelogheader(self):
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"""v10 does not have a changelog header chunk"""
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return {}
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def manifestheader(self):
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"""v10 does not have a manifest header chunk"""
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return {}
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def filelogheader(self):
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"""return the header of the filelogs chunk, v10 only has the filename"""
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l = self.chunklength()
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if not l:
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return {}
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fname = readexactly(self._stream, l)
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return dict(filename=fname)
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def _deltaheader(self, headertuple, prevnode):
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node, p1, p2, cs = headertuple
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if prevnode is None:
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deltabase = p1
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else:
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deltabase = prevnode
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return node, p1, p2, deltabase, cs
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def deltachunk(self, prevnode):
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l = self.chunklength()
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if not l:
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return {}
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headerdata = readexactly(self._stream, self.deltaheadersize)
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header = struct.unpack(self.deltaheader, headerdata)
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delta = readexactly(self._stream, l - self.deltaheadersize)
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node, p1, p2, deltabase, cs = self._deltaheader(header, prevnode)
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return dict(node=node, p1=p1, p2=p2, cs=cs,
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deltabase=deltabase, delta=delta)
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class headerlessfixup(object):
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def __init__(self, fh, h):
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self._h = h
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self._fh = fh
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def read(self, n):
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if self._h:
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d, self._h = self._h[:n], self._h[n:]
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if len(d) < n:
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d += readexactly(self._fh, n - len(d))
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return d
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return readexactly(self._fh, n)
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def readbundle(fh, fname):
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header = readexactly(fh, 6)
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if not fname:
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fname = "stream"
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if not header.startswith('HG') and header.startswith('\0'):
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fh = headerlessfixup(fh, header)
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header = "HG10UN"
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magic, version, alg = header[0:2], header[2:4], header[4:6]
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if magic != 'HG':
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raise util.Abort(_('%s: not a Mercurial bundle') % fname)
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if version != '10':
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raise util.Abort(_('%s: unknown bundle version %s') % (fname, version))
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return unbundle10(fh, alg)
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class bundle10(object):
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deltaheader = _BUNDLE10_DELTA_HEADER
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def __init__(self, lookup):
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self._lookup = lookup
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def close(self):
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return closechunk()
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def fileheader(self, fname):
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return chunkheader(len(fname)) + fname
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def revchunk(self, revlog, rev, prev):
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node = revlog.node(rev)
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p1, p2 = revlog.parentrevs(rev)
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base = prev
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prefix = ''
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if base == nullrev:
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delta = revlog.revision(node)
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prefix = mdiff.trivialdiffheader(len(delta))
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else:
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delta = revlog.revdiff(base, rev)
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linknode = self._lookup(revlog, node)
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p1n, p2n = revlog.parents(node)
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basenode = revlog.node(base)
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meta = self.builddeltaheader(node, p1n, p2n, basenode, linknode)
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meta += prefix
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l = len(meta) + len(delta)
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yield chunkheader(l)
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yield meta
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yield delta
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def builddeltaheader(self, node, p1n, p2n, basenode, linknode):
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# do nothing with basenode, it is implicitly the previous one in HG10
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return struct.pack(self.deltaheader, node, p1n, p2n, linknode)
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