Find size of a function in C

Question

I am learning function pointers,I understand that we can point to functions using function pointers.Then I assume that they stay in memory.Do they stay in stack or heap?Can

Answer 1

There's an interesting way to discover the size of the function.

#define RETN_empty 0xc3
#define RETN_var   0xc2  
typedef unsigned char BYTE;
size_t FunctionSize(void* Func_addr) {
    BYTE* Addr = (BYTE*)Func_addr;
    size_t function_sz = 0;
    size_t instructions_qt = 0;
        while(*Addr != (BYTE)RETN_empty && *Addr != (BYTE)RETN_var) {
            size_t inst_sz = InstructionLength((BYTE*)Addr);
            function_sz += inst_sz;
            Addr += inst_sz;
            ++instructions_qt;
        }
    return function_sz + 1;
}

But you need a function that returns the size of the instruction. You can find a function that finds the Instruction Length here: Get size of assembly instructions. This function basically keeps checking the instructions of the function until it finds the instruction to return (RETN)[ 0xc3, 0xc2], and returns the size of the function.