#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
#include <errno.h>

extern int errno;

void usr1(int sig) ;
void usr2(int sig) ;
void hup(int sig) ;
void intr(int sig);

int loop=1;
pid_t mypid;
int counter=0;

main () {

     char buf[100];
     int len;


     mypid = getpid();

     if (  SIG_ERR == signal(SIGUSR1, usr1)) {
	perror("Unable to set signal handler");
     }
     if (  SIG_ERR == signal(SIGUSR2, usr2)) {
	perror("Unable to set signal handler");
     }
     if (  SIG_ERR == signal(SIGHUP, hup)) {
	perror("Unable to set signal handler");
     }
     if (  SIG_ERR == signal(SIGINT, intr)) {
	perror("Unable to set signal handler");
     }


     printf("The process (%d) is set for a USR1, USR2, HUP, INT\n",mypid);
     while (loop) {
      
     }
     printf("Out of the loop, type something in\n");


doover:
     len = read(0,buf,100);
     buf[len-1]='\0';
     printf("We were able to read a <%s>, len = %d\n",buf,len);
     if (errno == EINTR) {
	errno = 0;
        printf("In doover loop\n");
	goto doover;
     }

}

void usr1(int sig){
    
    printf("In usr1, got %d\n",sig);
     if (  SIG_ERR == signal(SIGUSR1,SIG_DFL)) {
	perror("Unable to set signal handler");
     }
    
    raise(SIGUSR1);

}

void usr2(int sig){
    
     printf("In usr2, got %d\n",sig);

     printf (" Resetting SIGUSR2 handler \n");

      if (  SIG_ERR == signal(SIGUSR2, usr2)) {
	perror("Unable to set signal handler");
     }
}

void hup(int sig){
    
     printf("In hup, got %d\n",sig);
     printf (" Resetting SIGHUP handler \n");
     kill (mypid,sig);
     printf("counter=%d\n",counter++);
     if (  SIG_ERR == signal(SIGHUP, hup)) {
	perror("Unable to set signal handler");
     }
     printf("counter=%d\n",counter--);
}

void intr(int sig){
    
    printf("In intr, got %d\n",sig);
    loop=0;
}