I was reading this question because I'm trying to find the size of a function in a C++ program, It is hinted at that there may be a way that is platform specific. My targeted platform is windows
The method I currently have in my head is the following:
1. Obtain a pointer to the function
2. Increment the Pointer (& counter) until I reach the machine code value for ret
3. The counter will be the size of the function?
Edit1: To clarify what I mean by 'size' I mean the number of bytes (machine code) that make up the function.
Edit2: There have been a few comments asking why or what do I plan to do with this. The honest answer is I have no intention, and I can't really see the benefits of knowing a functions length pre-compile time. (although I'm sure there are some)
This seems like a valid method to me, will this work?
Wow, I use function size counting all the time and it has lots and lots of uses. Is it reliable? No way. Is it standard c++? No way. But that's why you need to check it in the disassembler to make sure it worked, every time that you release a new version. Compiler flags can mess up the ordering.
static void funcIwantToCount()
{
// do stuff
}
static void funcToDelimitMyOtherFunc()
{
__asm _emit 0xCC
__asm _emit 0xCC
__asm _emit 0xCC
__asm _emit 0xCC
}
int getlength( void *funcaddress )
{
int length = 0;
for(length = 0; *((UINT32 *)(&((unsigned char *)funcaddress)[length])) != 0xCCCCCCCC; ++length);
return length;
}
It seems to work better with static functions. Global optimizations can kill it.
P.S. I hate people, asking why you want to do this and it's impossible, etc. Stop asking these questions, please. Makes you sound stupid. Programmers are often asked to do non-standard things, because new products almost always push the limits of what's availble. If they don't, your product is probably a rehash of what's already been done. Boring!!!