UE Explorer can view the code, but how do I modify it?

[sskillz]

So your saying that if it doesn't run the decompressed package its a good chance that it checks the file hash?

I used to code once....
About LZO, I tried this:

Code:

int __lzo_cdecl_main main(int argc, char *argv[])
{
    if (lzo_init() != LZO_E_OK) { printf("internal error - lzo_init() failed !!!\n"); return 4; }
    
    FILE *fi = NULL;
    FILE *fo = NULL;
    unsigned char bufferin[37210] = { 0 }; //Size of the first chunk block (After all the checks blocks compressed and ucompressed sizes)
    unsigned char bufferout[131072] = { 0 }; //Block size
    memset(bufferin, 0, sizeof(bufferin));
    memset(bufferout, 0, sizeof(bufferout)); 
    fi = fopen("in.bin", "rb");
    if (fi == NULL) { printf("cannot open input file %s\n", "in.bin"); exit(1); }
    fo = fopen("out.bin", "wb");
    if (fo == NULL) { printf("cannot create output file %s\n", "out.bin"); exit(1); }
    
    int i = fread(bufferin, 1, sizeof(bufferin), fi);
    lzo_uint inlen = sizeof(bufferin);
    lzo_uint outlen = sizeof(bufferout);
    int r = lzo1_decompress(bufferin, inlen, bufferout, &outlen, NULL);
    if (r == LZO_E_OK) { 
          
          fwrite(bufferout, 1, 1024, fo);
          printf("done");
    }
    else
    {
        printf("internal error - compression failed: %d\n", r);
        return 2;
    }
    fclose(fi);
    fclose(fo);

    return 0;
}

With  lzo1_decompress it gets LZO_E_INPUT_OVERRUN.
With  lzo1x_decompress it completes but the output data is wrong compared to orignal (But the all the 00 bytes are in the right place, Good sign that it is the first block of the chunk)
With  lzo1c_decompress the program crushes.

And ideas, Even if it won't help me for the final goal, I just want to finish it :|

[sskillz]

So you are using x and not c when you see a package that is compressed with LZO?
What did you mean by LZO (C-version) on you reply to this thread?
http://www.gildor.org/smf/index.php/topic,1278.0.html

[sskillz]

And about what I did was:
1) I used UE Explorer to open the compressed file which showed me all the compressed chunks with their UC Offset, UC Size, C Offset, C Size.
2) I got those values for the compressed chunk that holds the value I want to change: 12443150,     1048555,      2707149,       285394, Respectively
3) I extracted the first 16 bytes of the header at that "C Offset", they gave me:
tag: 0x9E2A83C1 = PACKAGE_FILE_TAG
BlockSize: 131072
CompressedSize: 285314
UncompressedSize: 1048555
Which shows me that part is at least correct, since the uncompressed size matches the first.
4) I calculated that  I need 8 blocks: UncompressedSize / BlockSize = 7.9998
5) I followed 8  4 byte pairs for each compressed block, they gave me:
First block, c_size = 37210, u_size=131072
2nd   block, c_size = 18667, u_size=131072
3rd   block, c_size = 25844, u_size=131072
4rd   block, c_size = 27692, u_size=131072
5rd   block, c_size = 40648, u_size=131072
6rd   block, c_size = 46525, u_size=131072
7rd   block, c_size = 51358, u_size=131072
8rd   block, c_size = 37370, u_size=131051
which if you add all the uncompressed sizes of all the blocks you get 104855 total uncompressed size like before
and if you add the compressed sizes you get 285314, which I figured you need to add the header size: 16 and the u_size, c_sizes pairs: 8*2*4 = 64
if you add it all, you get 285314 + 64 + 16 = 285394 total  like it should, so I figured that part is correct.
* I also verified that after those 285314 bytes I get the next PACKAGE_FILE_TAG
6) Than if I understand right, follows all the compressed blocks together, so I dumped the first 37210 bytes to a different file (in.bin).
7) Than I tried the decompress LZO program on it, which gave the results I posted before.


Do you see anything wrong about my calculations? Maybe I needed all the blocks data together?
So you are using lzo1x one right? Could you show me a snippet?

And really, Thanks for your patience and your quick responses.

[Gildor]

My congratulations with your experiments !
I warned you that you'll just waste your time with compression