1 files changed, 107 insertions, 0 deletions

diff --git a/makecab.py b/makecab.py
new file mode 100755
index 0000000..befa94a
--- /dev/null
+++ b/makecab.py
@@ -0,0 +1,107 @@
+#!/usr/bin/env python
+
+import sys
+import os
+import time
+import zlib
+import struct
+from collections import namedtuple
+
+CFHEADER_s = struct.Struct("<4sLLLLLBBHHHHH")
+CFHEADER = namedtuple("CFHEADER", "sig res0 size res1 firstfile res2 "
+                      "verminor vermajor folders files flags setid icabinet")
+CFHEADER_sig = "MSCF"
+
+CFFOLDER_s = struct.Struct("<LHH")
+CFFOLDER = namedtuple("CFFOLDER", "firstdata ndata compresstype")
+
+CFFILE_s = struct.Struct("<LLHHHH")
+CFFILE = namedtuple("CFFILE", "size offset ifolder date time attrs")
+
+CFDATA_s = struct.Struct("<LHH")
+CFDATA = namedtuple("CFDATA", "checksum compressedlen uncompressedlen")
+
+def mszip(data):
+    compressor = zlib.compressobj(9, zlib.DEFLATED, -zlib.MAX_WBITS,
+                                  zlib.DEF_MEM_LEVEL, zlib.Z_DEFAULT_STRATEGY)
+    compressed = compressor.compress(data)
+    compressed += compressor.flush()
+    return "CK" + compressed # add MSZIP header
+
+def packdate(y,m,d):
+    return ((y - 1980) << 9) | (m << 5) | d
+def packtime(h,m,s):
+    return ((h << 11) | (m << 5) | (s >> 1))
+
+def checksum(data):
+    data += "\0" * (3 & -len(data)) # pad to multiple of 4 bytes
+    toret = 0
+    for offset in xrange(0, len(data), 4):
+        toret ^= struct.unpack_from("<L", data, offset)[0]
+    return toret
+
+def build_cab(files):
+    uncompressed_data = ""
+    fileheaders = ""
+    for name, data, mtime in files:
+        mtime_u = time.gmtime(mtime)
+        fileheader = CFFILE(
+            size=len(data), offset=len(uncompressed_data), ifolder=0, attrs=0,
+            date=packdate(mtime_u.tm_year, mtime_u.tm_mon, mtime_u.tm_mday),
+            time=packtime(mtime_u.tm_hour, mtime_u.tm_min, mtime_u.tm_sec))
+        uncompressed_data += data
+        fileheaders += CFFILE_s.pack(*fileheader) + name + "\0"
+
+    compressed_data = ""
+    offset = 0
+    n_data_blocks = 0
+    while offset < len(uncompressed_data):
+        uncompressed_block = uncompressed_data[offset:offset+0x8000]
+        compressed_block = mszip(uncompressed_block)
+        blockheader = CFDATA(
+            checksum=0,
+            compressedlen=len(compressed_block),
+            uncompressedlen=len(uncompressed_block))
+        header_after_checksum = CFDATA_s.pack(*blockheader)[4:]
+        blockheader = blockheader._replace(
+            checksum=checksum(header_after_checksum + compressed_block))
+        compressed_data += CFDATA_s.pack(*blockheader) + compressed_block
+        offset += len(uncompressed_block)
+        n_data_blocks += 1
+
+    totalsize = (CFHEADER_s.size +
+                 CFFOLDER_s.size +
+                 len(fileheaders) +
+                 len(compressed_data))
+
+    header = CFHEADER(
+        sig=CFHEADER_sig, res0=0, res1=0, res2=0,
+        vermajor=1, verminor=3, folders=1, files=len(files),
+        flags=0, setid=0, icabinet=0, size=totalsize,
+        firstfile=CFHEADER_s.size + CFFOLDER_s.size)
+
+    folder = CFFOLDER(
+        ndata=n_data_blocks, compresstype=1,
+        firstdata = (CFHEADER_s.size + CFFOLDER_s.size + len(fileheaders)))
+
+    return (CFHEADER_s.pack(*header) +
+            CFFOLDER_s.pack(*folder) +
+            fileheaders +
+            compressed_data)
+
+def main():
+    args = sys.argv[1:]
+    outfile = args.pop(0)
+    files = []
+    while len(args) > 0:
+        cabname = args.pop(0)
+        filename = args.pop(0)
+        with open(filename, "rb") as f:
+            filedata = f.read()
+        files.append((cabname, filedata, os.stat(filename).st_mtime))
+    cabdata = build_cab(files)
+    with open(outfile, "wb") as f:
+        f.write(cabdata)
+
+if __name__ == '__main__':
+    main()