renamecharacters.py

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

# Rename characters in LoG save files.

import argparse
import struct
import zlib
import re
import io

MAX_CHAR_NAME_SZ = 20       # Max character name size is set to 20 characters

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

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

        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)
            block_data_edit = bytearray(block_data)
            delta_sz = 0

            if block_name == "CHAR":
                char_id       = struct.unpack("<H",block_data[10:12])[0]
                name_tag      =                    block_data[12:16]
                name_block_sz = struct.unpack("<L",block_data[16:20])[0]
                name_sz       = struct.unpack("<L",block_data[24:28])[0]
                if name_tag == "CHAM":
                    print "    Found character %s" % str(block_data[28:28+name_sz])
                    name_too_long = True
                    while name_too_long:
                        new_name = raw_input("    New name (press Enter to keep identical)? ")
                        name_too_long = (len(new_name) > MAX_CHAR_NAME_SZ)
                        if name_too_long:
                            print "    Name too long (%d chars max)" % MAX_CHAR_NAME_SZ

                    if len(new_name) != 0:
                        delta_sz                       = len(new_name) - name_sz
                        block_data_edit[16:20]         = struct.pack("<L", name_block_sz + delta_sz)
                        block_data_edit[24:28]         = struct.pack("<L", len(new_name))
                        block_data_edit[28:28+name_sz] = bytearray(new_name)

            uncomp_data_out += block_name + struct.pack("<L", block_size + delta_sz) + str(block_data_edit)

        savefile_out = open(out_filename, 'wb')
        savefile_out.write("GRIM" + struct.pack("<LL", 4, len(uncomp_data_out)))
        savefile_out.write(zlib.compress(uncomp_data_out))

        print "\nEdited savegame is: %s" % out_filename

        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='Rename characters LoG save files')
    parser.add_argument('savefiles', metavar='savefile', nargs=1,
                       help='LoG save files (v1.1.4 or above) with .sav extension')
    parser.add_argument('-k', dest='keep_uncompressed', action='store_true',
                        help='Keep the uncompressed data (with extension .uncompressed.sav)')

    args = parser.parse_args()

    # Parse the first savefile and rename characters
    parse_savegame(args.savefiles[0], keep_uncompressed = args.keep_uncompressed)

if __name__ == "__main__":
    main()