Raspberry Pi interrupt to signal conversion C source code, user space application

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This code is from project: Raspberry pi interrupt to signal conversion, kernel to user space

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wait_for_signal.c

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

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <string.h>

#define SIGNAL_TO_WATCH  34 

#define DEVICE_PATH "/dev/m_gpioSignal"


/****************************************************************************/
/* Function which will write program pid to device secified by path,        */
/****************************************************************************/
void reloadKernelHandler() {
   int devHandle  = -1;
   char buff[10] = { 0 }; 

   if ( (devHandle = open(DEVICE_PATH, O_WRONLY)) == -1) {
      perror("open");
      return;
   }

   sprintf(buff, "%d\n", getpid());

   if (write(devHandle, buff, strlen(buff)) == -1)
      perror("write");

   close(devHandle);

   return;
}


/****************************************************************************/
/* Function triggered by signal                                             */
/****************************************************************************/
static void run_function(int sig, siginfo_t *siginfo, void *c)
{
   printf ("Got signal\n");

   usleep(100);

   // reenable interrupt in kernel, and once again write own pid
   reloadKernelHandler();
}


/****************************************************************************/
/* Main.                                                                    */
/****************************************************************************/
int main(int argc, char *argv[]) {

   struct sigaction act = { 0 };

   act.sa_sigaction = &run_function;
   act.sa_flags = SA_SIGINFO;

   // attach own function to signal 
   if (sigaction(SIGNAL_TO_WATCH, &act, NULL) < 0) {
      perror ("error");
      return 1;
   }

   // enable kernel interrupt and send own pid to kernel
   reloadKernelHandler();

   // loop
   while(1);

   return 0;
}