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#!/usr/bin/python -t
import gzip
import types
import struct
import sys
from dumpMetadata import byteranges
BUF_SIZE = 32768
def get_signature_from_file(sigfile):
f = open(sigfile, "r")
sig = f.read()
f.close()
return sig
def make_delta_from_sig(src_delta, sigfile, dst_delta):
# Open source deltarpm and read/write header
(range_start, range_end) = byteranges(src_delta)
sfd = open(src_delta, "r")
dfd = open(dst_delta, "w")
dfd.write(sfd.read(range_end))
# Switch to compressed mode
try:
scfd = gzip.GzipFile("", "rb", 9, sfd)
except:
raise zlibError("Data not stored in gzip format")
if scfd.read(4) != "DLT3":
raise Exception("Not a deltarpm")
dcfd = gzip.GzipFile("", "wb", 9, dfd)
dcfd.write("DLT3")
# Get nevr and write it
len_str = scfd.read(4)
(length, ) = struct.unpack('>I', len_str)
nevr_length = len_str
nevr = scfd.read(length)
dcfd.write("%s%s" % (nevr_length, nevr))
# Read sequence and write it
len_str = scfd.read(4)
(length, ) = struct.unpack('>I', len_str)
dcfd.write(len_str + scfd.read(length))
# Read md5 and discard, replacing with \x00's. New versions of deltarpm
# will see this and use the rpm's md5 checksum rather than this one.
scfd.read(16)
dcfd.write("\x00" * 16)
# Read and write target size
dcfd.write(scfd.read(4))
# Read and write other data
dcfd.write(scfd.read(12))
len_str = scfd.read(4)
(length, ) = struct.unpack('>I', len_str)
dcfd.write(len_str + scfd.read(length*2*4))
dcfd.write(scfd.read(4))
# Read and write lead
dcfd.write(scfd.read(96))
# Write signature from signature file and skip signature in src deltarpm
signature = get_signature_from_file(sigfile)
dcfd.write(signature)
scfd.read(8)
binindex = scfd.read(4)
(sigindex, ) = struct.unpack('>I', binindex)
bindata = scfd.read(4)
(sigdata, ) = struct.unpack('>I', bindata)
# each index is 4 32bit segments - so each is 16 bytes
sigindexsize = sigindex * 16
sigsize = sigdata + sigindexsize
# we have to round off to the next 8 byte boundary
disttoboundary = (sigsize % 8)
if disttoboundary != 0:
disttoboundary = 8 - disttoboundary
scfd.read(sigsize + disttoboundary)
data = scfd.read(BUF_SIZE)
while data != "":
dcfd.write(data)
data = scfd.read(BUF_SIZE)
def main():
if len(sys.argv) != 4:
print "Usage: %s <original deltarpm> <signature> <new deltarpm>" % sys.argv[0]
sys.exit(1)
make_delta_from_sig(sys.argv[1], sys.argv[2], sys.argv[3])
if __name__ == '__main__':
main()
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