parsesavegame.py

#!/usr/bin/env python
# python 2.7

import argparse
import struct
import zlib
import re
import io

cimg_ids    = []
cimg_blocks = dict()

# Savegame format:
# ----------------
# 4752 494D 0400 0000 F14E 0B00 789C EC7D ... ...
# ^^^^ ^^^^                                             Block name = "GRIM"
#           ^^^^ ^^^^                                   Block size = 4 (little-endian)
#                     ^^^^ ^^^^                         Uncompressed data size in bytes (little-endian)
#                               ^^^^                    Zlib data header (always 789C)
#                                    ^^^^ ^^^^ ^^^^     Zlib data

def parse_savegame(filename, insert_cimg = False, keep_uncompressed = False):
    global cimg_ids, cimg_blocks
    if insert_cimg:
        cimg_ids = []
    else:
        cimg_blocks = dict()

    savefile_in, savefile_out, uncompfile_out = None, None, None
    try:
        savefile_in = open(filename,'rb')
        print "Parsing %s:" % filename

        if insert_cimg:
           out_filename = re.sub(r'\.sav', '.edited.sav', filename)
           if out_filename == filename:
                raise Exception("Input savefiles must have the .sav extension")
           savefile_out = open(out_filename, 'wb')

        uncomp_data_out = ""

        filetype = savefile_in.read(4)
        if filetype != "GRIM":
            raise Exception("Not a valid savefile")

        block_size= savefile_in.read(8)     # Skip the next 8 bytes
        zlib_data = savefile_in.read(-1)    # Read all the rest (= the compressed data)

        data_stream = io.BytesIO(zlib.decompress(zlib_data))

        while True:
            skip_flag = False

            block_name = data_stream.read(4)
            if block_name == "":
                break
            block_size = struct.unpack("<L",data_stream.read(4))[0]
            block_data = data_stream.read(block_size)

            if block_name == "CHAR":
                char_id  = struct.unpack("<H",block_data[10:12])[0]
                name_tag =                    block_data[12:16]
                name_sz  = struct.unpack("<L",block_data[24:28])[0]
                if name_tag == "CHAM":
                    print "    Found character %s (ID: %04X)" % (str(block_data[28:28+name_sz]), char_id)

                if insert_cimg:
                    cimg_ids.append(char_id)
                    if char_id not in cimg_blocks:
                        raise Exception("No custom portrait for character ID %04X" % char_id)

            elif block_name == "CIMG":
                if insert_cimg:
                    skip_flag = True        # Skip this block (will be replaced by a new custom img)
                else:
                    char_id  = struct.unpack("<H",block_data[10:12])[0]
                    print "    Found custom portrait (ID: %04X)" % char_id
                    cimg_blocks[char_id] = block_name + struct.pack("<L", block_size) + block_data

            elif block_name == "PRTY":
                if insert_cimg:
                    for char_id in cimg_ids:
                        uncomp_data_out += cimg_blocks[char_id]
                    print "    Inserted custom portraits"

            if not skip_flag:
                uncomp_data_out += block_name + struct.pack("<L", block_size) + block_data

        if insert_cimg:
            savefile_out.write("GRIM" + struct.pack("<LL", 4, len(uncomp_data_out)))
            savefile_out.write(zlib.compress(uncomp_data_out))

        if keep_uncompressed:
            uncomp_filename = re.sub(r'\.sav', '.uncompressed.sav', filename)
            if uncomp_filename == filename:
                raise Exception("Input savefiles must have the .sav extension")
            uncompfile_out = open(uncomp_filename, 'wb')
            uncompfile_out.write(uncomp_data_out)

    finally:
        if savefile_in:
            savefile_in.close()
        if savefile_out:
            savefile_out.close()
        if uncompfile_out:
            uncompfile_out.close()

#
# Main()
#
def main():
    parser = argparse.ArgumentParser(description='Copy custom portraits from one LoG save file to another')
    parser.add_argument('savefiles', metavar='savefile', nargs=2,
                       help='LoG save files (v1.1.4 or above) with .sav extension')
    parser.add_argument('-k', dest='keep_compressed', action='store_true',
                        help='Keep the uncompressed data (with extension .uncompressed.sav)')

    args = parser.parse_args()

    # Parse the first savefile to get the custom portraits
    parse_savegame(args.savefiles[0])

    # Insert the custom portraits in the second savefile (or, replace existing ones)
    parse_savegame(args.savefiles[1], True, args.keep_compressed)

if __name__ == "__main__":
    main()