/*
 * signal-test-syscall-correct.c
 */

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

void handler(int signum);

int main(int argc, char *argv[])
{
    char buf[10];
    struct sigaction sa;

    /* set up the struct that defines what to do on receipt of a signal */
    memset(&sa, '\0', sizeof(sa));
    sa.sa_handler = handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;

    /* associate that action with a particular signal */
    if(sigaction(SIGUSR1, &sa, NULL) < 0) {
        perror("sigaction");
        exit(1);
    }

    /* be helpful */
    printf("My pid is %d\n", getpid());

    write(1, "waiting for a signal\n", 21);
    while(1) {
        if(read(0, buf, 10) < 0) {
            /* if we were interrupted by a signal, try again */
            if(errno == EINTR) {
                continue;
            /* otherwise bail entirely */
            } else {
                perror("read");
                exit(1);
            }
        }
        printf("read(2) returned successfully\n");
        break;
    }
}

void handler(int signum)
{
    printf("received signal %d\n", signum);
}