/*
 * Copyright 2001 Sun Microsystems, Inc. ALL RIGHTS RESERVED
 * Use of this software is authorized pursuant to the
 * terms of the license found at
 * http://developers.sun.com/berkeley_license.html
 */

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <dlfcn.h>

static void handle_crash(int sig)
{
  char buf[128];

  printf("Processing signal %d\n", sig);
  /* generate traceback to stdout and copy to /var/tmp/traceback.txt */
  sprintf(buf, "/usr/proc/bin/pstack %d "
    "|/bin/tee /var/tmp/traceback.txt\n", (int)getpid());
  /* undefine LD_PRELOAD to avoid 64-bit problems */
  (void)putenv("LD_PRELOAD=");
  system(buf);
  /* a file in /var/tmp will survive a reboot but not in /tmp */
  printf("A copy of the traceback is stored in /var/tmp/traceback.txt\n");
  exit(1);
}

static int (*sigaction_pointer)();

/* pragma init is SVR4-specific, executes before main() */
#pragma init (install_handlers)
static void install_handlers(void)
{
  struct sigaction action;

  action.sa_handler = handle_crash;
  if (sigemptyset(&action.sa_mask))
    perror("sigemptyset() failure");

  /* To avoid being caught in the sigaction interposer below,
     directly call the real sigaction(2) here */
  if(sigaction_pointer == NULL)
    sigaction_pointer = (int (*)())dlsym(RTLD_NEXT, "sigaction");   
  if (sigaction_pointer(SIGSEGV, &action, NULL))
    perror("Can't set up a signal handler for SIGSEGV");
  if (sigaction_pointer(SIGBUS, &action, NULL))
    perror("Can't set up a signal handler for SIGBUS");
}

/*
 * Remove application's signal handlers for SIGSEGV and SIGBUS
 * by interposing on signal(3C), sigset(3C) and sigaction(2)
 */

/* Simplify prototyping */
typedef void Sigfunc(int);

Sigfunc *signal (int sig, Sigfunc *disp)
{
  static Sigfunc * (*func)();
  
  if(func == NULL)
    func = (Sigfunc *(*)())dlsym(RTLD_NEXT, "signal");

  if(sig == SIGSEGV || sig == SIGBUS)
    return(SIG_DFL);
  else
    return (func(sig, disp));
}

Sigfunc *sigset (int sig, Sigfunc *disp)
{
  static Sigfunc * (*func)();
  
  if(func == NULL)
    func = (Sigfunc *(*)())dlsym(RTLD_NEXT, "sigset");

  if(sig == SIGSEGV || sig == SIGBUS)
    return(SIG_DFL);
  else
    return (func(sig, disp));
}

int sigaction(int sig, const struct sigaction *act,
          struct sigaction *oact)
{
  if(sig == SIGSEGV || sig == SIGBUS)
    return(0);
  else
    return (sigaction_pointer(sig, act, oact));
}