/prog/ - Programming★

I'm working with RE'ing files from a game.

I've always wanted a small language that represents the structure of data in a file. It'd be a quick way to extract a packed data blob into something more readable. Any ideas?

using PNGType.rev;

type levelType
{
uint32 title_length;
string[title_string_length] title;
customPNGType() theThumbnail;
}

>>2636

>I've always wanted a small language that represents the structure of data in a file.

there is a language for doing exactly that.

sadly i can't remember anything about it, not even its name or in which context i heard about it.

it's been ages since i played around with game files, now i don't want to waste any time and energy on proprietary shit anymore.

either it works or trash.jpg

i'm glad though that others are taking up the fight to free the data.

>>2655

I found a tool exactly describing what I mean in the hex editor known as 010, which is (wait for it) closed source and paid.

Reading beginners.re book. lena151 tuts teached me the basics through practical examples, but I think this book is good next step (and also has arm/mips, 64bit covered)

>>2636

>>2655

I know I'm a month late, but Erlang does exactly that very well.

It sucks for a lot of other things (anything involving strings), and is purely functional, but its packing and unpacking syntax is a dream.

http://www.erlang.org/documentation/doc-5.6/doc/programming_examples/bit_syntax.html

this code

void f()
{
char *buf=(char*)alloca (600);
snprintf (buf, 600, "hi! %d, %d, %d\n", 1, 2, 3); 
puts (buf);
};

when compiled should be

.LC0:
.string "hi! %d, %d, %d\n"
f:
push    ebp
mov     ebp, esp
push    ebx
sub     esp, 660
lea     ebx, [esp+39]
and     ebx, -16
; align pointer by 16-bit border
mov     DWORD PTR [esp], ebx
; s
mov     DWORD PTR [esp+20], 3
mov     DWORD PTR [esp+16], 2
mov     DWORD PTR [esp+12], 1
mov     DWORD PTR [esp+8], OFFSET FLAT:.LC0 ; "hi! %d, %d, %d\n"
mov     DWORD PTR [esp+4], 600
; maxlen
call    _snprintf
mov     DWORD PTR [esp], ebx
; s
call    puts
mov     ebx, DWORD PTR [ebp-4]
leave
ret

my question is, why is there lea ebx, [esp+39] and not just lea ebx, [esp] ?

>>2636

Sounds like good use case for a common lisp macro.

How the fuck do I obfuscate javascript?

>>2923

de-obfuscate javascript rather

>>2923

Use stuff people are less likely to know about I suppose like & 1 instead of % 2. Use the ternary conditional operator ?:. Eg:

Number.prototype.isOdd = function() {

return this & 1 === 1?true:false;

};

Still not particularly difficult to read though.

>>2636

you can do that with 010 Editor. it's a really good hex editor for reversing file formats. it costs money but is really easy to crack. it's for windows though.

>>2874

i would assume that you need to do that because when you align the pointer you need a certain amount of space to make sure that the aligned pointer doesnt shrink the buffer. you're pretty much always going to have a little bit of the buffer left over at the end after the alignment but youre always guaranteed the size that you requested to be allocated.

lea ebx, [esp+39] gives you that breathing room for the alignment. since the stack address isn't known at compile time you need to do that for the and operation.

>>2998

That's pretty awesome. I'd love to see more.