/*-------------------------------------------------------------------*/
/* testsignal.c                                                      */
/* The signal system call.                                           */
/*-------------------------------------------------------------------*/

#include <stdio.h>
#include <assert.h>
#include <signal.h>

/*-------------------------------------------------------------------*/

void mySignalHandler(int iSignal)

/* This function is intended to be a handler for signals of various
   types.  Print iSignal to stdout, and then re-register this function 
   as the handler for signals of type iSignal. */

{
   void (*pfRet)(int); 
   printf("In mySignalHandler with argument %d\n", iSignal);
   pfRet = signal(iSignal, mySignalHandler);
   assert(pfRet != SIG_ERR);
}

/*-------------------------------------------------------------------*/

int main(int argc, char *argv[])

/* Illustrate the signal function.
   
   Note that this program can be exited only by sending it a SIGKILL
   signal from another terminal. */

{
   void (*pfRet)(int); 

   pfRet = signal(SIGHUP, mySignalHandler);    /* 1 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGINT, mySignalHandler);    /* 2 (generated by ^C) */
   assert(pfRet != SIG_ERR);
   
   pfRet = signal(SIGQUIT, mySignalHandler);   /* 3 (generated by ^\) */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGILL, mySignalHandler);    /* 4 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGTRAP, mySignalHandler);   /* 5 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGABRT, mySignalHandler);   /* 6 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGBUS, mySignalHandler);    /* 7 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGFPE, mySignalHandler);    /* 8 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGKILL, mySignalHandler);   /* 9 (should fail) */
   assert(pfRet == SIG_ERR);

   pfRet = signal(SIGUSR1, mySignalHandler);   /* 10 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGSEGV, mySignalHandler);   /* 11 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGUSR2, mySignalHandler);   /* 12 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGPIPE, mySignalHandler);   /* 13 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGALRM, mySignalHandler);   /* 14 (generated by alarms) */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGTERM, mySignalHandler);   /* 15 (default from kill cmd) */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGCHLD, mySignalHandler);   /* 17 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGCONT, mySignalHandler);   /* 18 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGSTOP, mySignalHandler);   /* 19 (should fail) */
   assert(pfRet == SIG_ERR);

   pfRet = signal(SIGTSTP, mySignalHandler);   /* 20 (generated by ^Z) */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGTTIN, mySignalHandler);   /* 21 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGTTOU, mySignalHandler);   /* 22 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGURG, mySignalHandler);    /* 23 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGXCPU, mySignalHandler);   /* 24 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGXFSZ, mySignalHandler);   /* 25 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGVTALRM, mySignalHandler); /* 26 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGPROF, mySignalHandler);   /* 27 (for profilers) */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGWINCH, mySignalHandler);  /* 28 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGIO, mySignalHandler);     /* 29 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGPWR, mySignalHandler);    /* 30 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGSYS, mySignalHandler);    /* 31 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGRTMIN, mySignalHandler);  /* 32 */
   assert(pfRet != SIG_ERR);

   pfRet = signal(SIGRTMIN, mySignalHandler);  /* 33 */
   assert(pfRet != SIG_ERR);

   printf("Entering an infinite loop\n");
   for (;;)
      ;

   return 0;
}

/* Sample execution:

$ gcc -Wall -ansi -pedantic -o testsignal testsignal.c
$ testsignal
Entering an infinite loop
^CIn mySignalHandler with argument 2
^\In mySignalHandler with argument 3
^ZIn mySignalHandler with argument 20

*/