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  /*
   * This test validates an edge case within Pin.  Pin checks for and delivers
   * any pending asynchronous signals at the end of each trace.  However, it
   * handles any synchronous signals (i.e. faults) immediately.  There is a weird
   * edge case if Pin has a pending asynchronous signal at the time a synchronous
   * signal is generated.
   *
   * In an old version of Pin, there was a bug that caused the application's
   * signal mask to be set incorrectly in the above case.  This test forces the
   * edge case to occur, and then validates that the signal mask is set correctly.
   *
   * Forcing the edge case is a little tricky.  The test expects to handle two
   * signals: a VTALRM (from an i-timer) and a SEGV (by executing an invalid store).
   * To force the edge case, we want the VTALRM to be delivered while Pin is
   * executing the basic block that contains the invalid (faulting) store.  Obviously,
   * this is a very small timing window.  We use a special Pin tool to open up this
   * timing window.  The Pin tool finds the basic block that contains the faulting
   * store and inserts a long-running analysis routine at the first instruction of
   * this basic block.  This essentially causes the basic block to run for a very
   * long time, which makes it much more likely that the VTALRM will be delivered
   * during that basic block.
   */
  
  #include <signal.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/time.h>
  
  
  static void HandleSegv(int);
  static void HandleAlarm(int);
  static void CheckMask();
  static void MakeSegv();
  
  
  int main()
  {
      struct sigaction sigact;
      struct itimerval itval;
  
      sigact.sa_handler = HandleSegv;
      sigemptyset(&sigact.sa_mask);
      sigact.sa_flags = 0;
      if (sigaction(SIGSEGV, &sigact, 0) == -1)
      {
          fprintf(stderr, "Unable handle SEGV\n");
          return 1;
      }
  
      if (sigaction(SIGBUS, &sigact, 0) == -1)
      {
          fprintf(stderr, "Unable handle SEGV\n");
          return 1;
      }
  
      sigact.sa_handler = HandleAlarm;
      if (sigaction(SIGVTALRM, &sigact, 0) == -1)
      {
          fprintf(stderr, "Unable handle VTALRM\n");
          return 1;
      }
  
      itval.it_value.tv_sec = 0;
      itval.it_value.tv_usec = 100000;
      itval.it_interval.tv_sec = 0;
      itval.it_interval.tv_usec = 0;
      if (setitimer(ITIMER_VIRTUAL, &itval, 0) == -1)
      {
          fprintf(stderr, "Unable to set up alarm\n");
          return 1;
      }
  
      MakeSegv();
      return 0;
  }
  
  
  static void HandleSegv(int sig)
  {
      printf("Got SEGV\n");
      CheckMask();
      exit(0);
  }
  
  static void HandleAlarm(int sig)
  {
      printf("Got VTALRM\n");
      CheckMask();
  }
  
  
  static void CheckMask()
  {
      sigset_t mask;
      int sig;
  
      if (sigprocmask(SIG_SETMASK, 0, &mask) == -1)
      {
          fprintf(stderr, "Unable to get mask\n");
          exit(1);
      }
  
      for (sig = 1;  sig < 32;  sig++)
      {
          if (sigismember(&mask, sig))
          {
              printf("Signal %d blocked\n", sig);
              if (sig != SIGSEGV && sig != SIGVTALRM && sig != SIGBUS)
              {
                  fprintf(stderr, "Signal %d unexpectedly blocked\n", sig);
                  exit(1);
              }
          }
      }
  }
  
  
  static void MakeSegv()
  {
      volatile int * p;
      int i;
  
      /*
       * Make a big basic block, which the Pin tool can find.  The Pin tool
       * inserts an analysis call at the beginning of this block, which stalls
       * for a long time.  We expect that the VTALRM signal will be delivered
       * to Pin during the analysis call.  Pin should keep that signal pending
       * until the end of this basic block.
       */
      p = &i;
      *p = 1;
      *p = 2;
      *p = 3;
      *p = 4;
      *p = 5;
      *p = 6;
      *p = 7;
      *p = 8;
      *p = 9;
  
      /*
       * The following store must be in the same basic block as the stores above
       * in order for the test to be valid.
       *
       * This store causes a SEGV, thus forcing a synchronous signal to be delivered
       * while an asynchronous signal (the VTALRM) is pending inside of Pin.
       */
      p = (volatile int *)0x9;
      i = *p;
  }
  