/*
gcc -g -Wall -o test_sighandler -rdynamic test_sighandler.c

GNU/Linux:
./test_sighandler
Got signal 11, faulty address is 0xdeadbeef, from 5597bd471de0
Executable name = '/home/srs/Hurd/DEBs/test_cases/test_sighandler�', len = 47

GNU/Hurd:
./test_sighandler
Got signal 4
Executable name = './test_sighandler

', len = 21

Changing 0xdeadbeef to 0xbeadbeef gives:
./test_sighandler
Got signal 11, faulty address is 0xbeadbeef, from 8048986
Executable name = './test_sighandler

', len = 21
*/

#define _GNU_SOURCE
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <execinfo.h>
/* get REG_EIP/REG_RIP from ucontext.h */
#include <ucontext.h>

const char* getExecutableName()
{
  char link[1024];
  char exe[1024];

  //snprintf (link, sizeof link, "/proc/%d/exe", getpid());
  snprintf (link, sizeof link, "/proc/self/exe");
  if(readlink (link, exe, sizeof link)==-1) {
    fprintf(stderr,"ERRORRRRR\n");
    exit(1);
  }
  int len = strlen(exe);
  exe[len] = '\0';
  printf("Executable name = '%s', len = %d\n", exe, len);

  return 0;
}

void bt_sighandler(int sig, siginfo_t *info,
                   void *secret) {

  void *trace[16];
  char **messages = (char **)NULL;
  int i, trace_size = 0;
  ucontext_t *uc = (ucontext_t *)secret;

  /* Do something useful with siginfo_t */
  if (sig == SIGSEGV)
#ifdef __x86_64__
    printf("Got signal %d, faulty address is %p, "
           "from %llx\n", sig, info->si_addr, 
           uc->uc_mcontext.gregs[REG_RIP]);
#else
    printf("Got signal %d, faulty address is %p, "
           "from %x\n", sig, info->si_addr, 
           uc->uc_mcontext.gregs[REG_EIP]);
#endif
  else
    printf("Got signal %d\n", sig);

  trace_size = backtrace(trace, 16);
  /* overwrite sigaction with caller's address */
#ifdef __x86_64__
  trace[1] = (void *) uc->uc_mcontext.gregs[REG_RIP];
#else
  trace[1] = (void *) uc->uc_mcontext.gregs[REG_EIP];
#endif

  messages = backtrace_symbols(trace, trace_size);
  /* skip first stack frame (points here) */
  getExecutableName();
  printf("[bt] Execution path:\n");
  for (i=1; i<trace_size; ++i)
    printf("[bt] %s\n", messages[i]);
  exit(0);
}

int func_b(void)
{
  char *p = (char *)0xdeadbeef;
  //char *p = (char *)0xbeadbeef;
  //char *p = (char *)0x0;

  *p = 10;  /* CRASH here!! */

  return 0;
}

int main() {
  /* Install our signal handler */
  struct sigaction sa;

  sa.sa_sigaction = (void *)bt_sighandler;
  sigemptyset (&sa.sa_mask);
  sa.sa_flags = SA_RESTART | SA_SIGINFO;

  sigaction(SIGSEGV, &sa, NULL);
  sigaction(SIGILL, &sa, NULL);
  sigaction(SIGUSR1, &sa, NULL);
  /* ... add any other signal here */

  /* Do something */
  printf("%d\n", func_b());
}