Sys call experiments

process_fork.c

#include <dirent.h>
#include <error.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>

#include <time.h>
#include <unistd.h>

void sig_handler(int sig)
{
     switch(sig) {
     case SIGINT:
     case SIGTSTP:
     case SIGTRAP:
     case SIGABRT:
     case SIGFPE:
     case SIGUSR1:
     case SIGUSR2:
     case SIGSEGV:
     case SIGSTOP:
     case SIGCHLD:
     default:
	  printf("\n Ignoring signals except kill");
     }
}

void cur_time(void)
{
     time_t rawtime;
     struct tm * timeinfo;

     time ( &rawtime );
     timeinfo = localtime ( &rawtime );
     printf ("\nCurrent local time and date: %s", asctime (timeinfo));
}

void child_process(void)
{
     DIR *d;
     struct dirent *de;
     struct stat buf;
     int exists;
     
     printf("\n Opening the current directory");
     d = opendir(".");

     if (d == NULL) {
	  fprintf(stderr, "Error opening current directory\n");
	  exit(-1);
     }

     for (de = readdir(d); de != NULL; de = readdir(d)) {
	  exists = stat(de->d_name, &buf);
	  if (exists < 0) {
	       fprintf(stderr, "%s not found\n", de->d_name);
	  } else {
	       printf("%s %ld\n", de->d_name, buf.st_size);
	  }
     }
}

int main(int argc, char **argv)
{
     pid_t cpid;

     printf("\n PID of parent is : %ld", (long)getpid());

     signal(SIGINT, sig_handler);
     signal(SIGTSTP, sig_handler);
     signal(SIGTRAP, sig_handler);
     signal(SIGABRT, sig_handler);
     signal(SIGFPE, sig_handler);
     signal(SIGUSR1, sig_handler);
     signal(SIGUSR2, sig_handler);
     signal(SIGSEGV, sig_handler);
     signal(SIGSTOP, sig_handler);
     signal(SIGCHLD, sig_handler);

child:
     if ((cpid = fork()) != -1)
     {
	  while(1) {
	       printf("\n PID of child is : %ld", (long)getpid());
	       cur_time();
	       child_process();
	       sleep(10);
	  }

     }
     else
     {
	  wait(NULL);
	  goto child;
     }
     
     return 0;
}