/*-------------------------------------------------------------------*/
/* testsigaction.c                                                   */
/* Signal handling via the sigaction system call.                    */
/*-------------------------------------------------------------------*/

#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <ucontext.h>

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

void mySigAction(int iSignal, siginfo_t *psSigInfo, void *pvContext)

/* This function is intended to be a handler for signals of various 
   types.  Print iSignal to stdout, along with some of the information 
   about the signal contained in *psSigInfo, and some of the signal's 
   context contained in *pvContext. */

{
   ucontext_t *psContext = (ucontext_t*)pvContext;

   printf("--------------------------------------------\n");
   printf("In mySigAction with argument %d\n", iSignal);
   printf("\n");
   printf("Signal number:  %d\n", psSigInfo->si_signo);
   printf("Error code:     %d\n", psSigInfo->si_errno);
   printf("Signal code:    %d\n", psSigInfo->si_code);
   printf("\n");
   printf("Register EAX:  %x\n", psContext->uc_mcontext.gregs[REG_EAX]);
   printf("Register EBX:  %x\n", psContext->uc_mcontext.gregs[REG_EBX]);
   printf("Register ECX:  %x\n", psContext->uc_mcontext.gregs[REG_ECX]);
   printf("Register EDX:  %x\n", psContext->uc_mcontext.gregs[REG_ECX]);
   printf("Register ESP:  %x\n", psContext->uc_mcontext.gregs[REG_ESP]);
   printf("Register EBP:  %x\n", psContext->uc_mcontext.gregs[REG_EBP]);
   printf("Register EIP:  %x\n", psContext->uc_mcontext.gregs[REG_EIP]);
   printf("--------------------------------------------\n");
}

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

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

/* Illustrate the sigaction system call. */

{
   struct sigaction sSigAction;
   struct sigaction sOldSigAction;   

   /* Set sSigAction to indicate that we want to register a more
      elaborate signal handler -- one which accepts a siginfo_t
      parameter and a ucontext_t parameter containing information
      about the signal. */
   sSigAction.sa_flags = SA_SIGINFO;
   
   /* Set sSigAction to indicate that mySigAction is the signal
      handling function. */
   sSigAction.sa_sigaction = mySigAction;
   
   /* Set sSigAction to indicate that no signals should be blocked
      during execution of the signal handler. */
   sigemptyset(&sSigAction.sa_mask);
   
   /* Register sSigAction as the structure containing information
      to be used when this process receives a SIGINT signal.  The
      current state is assigned to sOldSigAction, in case we must
      restore it later. */
   sigaction(SIGINT, &sSigAction, &sOldSigAction);

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

   return 0;
}


/* Sample execution:

$ gcc -Wall -ansi -pedantic -o testsigaction testsigaction.c
$ testsigaction
Entering an infinite loop
^C--------------------------------------------
In mySigAction with argument 2

Signal number:  2
Error code:     0
Signal code:    128

Register EAX:  1a
Register EBX:  421328d4
Register ECX:  42130d00
Register EDX:  42130d00
Register ESP:  bfffe430
Register EBP:  bfffe558
Register EIP:  8048538
--------------------------------------------
^C--------------------------------------------
In mySigAction with argument 2

Signal number:  2
Error code:     0
Signal code:    128

Register EAX:  1a
Register EBX:  421328d4
Register ECX:  42130d00
Register EDX:  42130d00
Register ESP:  bfffe430
Register EBP:  bfffe558
Register EIP:  8048538
--------------------------------------------

*/