Is this stupid or just cool? Inspired by http://jpassing.com/2008/03/12/walking-the-stack-of-the-current-thread/

gdb.txt

$ gdb --args ./register
GNU gdb 6.3.50-20050815 (Apple version gdb-1824) (Thu Nov 15 10:42:43 UTC 2012)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin"...Reading symbols for shared libraries .. done

(gdb) break do_something
Breakpoint 1 at 0x1ebc: file register.c, line 7.
(gdb) r
Starting program: /Users/amos/Dev/tests/assy/register
warning: posix_spawn failed, trying execvp, error: 86
Reading symbols for shared libraries +......................... done

Breakpoint 1, do_something () at register.c:7
7         void * reg_eip = 0;
(gdb) info registers
eax            0x1ebb   7867
ecx            0x1      1
edx            0x90864725       -1870248155
ebx            0xbffff440       -1073744832
esp            0xbffff270       0xbffff270
ebp            0xbffff298       0xbffff298
esi            0x0      0
edi            0x0      0

Makefile

all: register

register : register.c
	gcc -save-temps -m32 -g -fno-pie -o $@ $^
	dsymutil $@

clean:
	rm -rf register register.dSYM

register.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

int do_something() {
  void * reg_eip = 0;
  __asm__ volatile ("1: movl $1b, %0" : "=r" (reg_eip));
  printf("eip = %p\n", reg_eip);

  void * reg_ebp = 0;
  __asm__ volatile ("movl %%ebp, %0" : "=r" (reg_ebp));
  printf("ebp = %p\n", reg_ebp);

  void * reg_esp = 0;
  __asm__ volatile ("movl %%esp, %0" : "=r" (reg_esp));
  printf("esp = %p\n", reg_esp);
}

int main(int argc, char ** argv) {
  do_something();
}