ece282/lab07/sigdemo1.c

/* sigdemo1.c - shows how a signal handler works.
 *            - run this and press Ctrl-C a few times
 *            - counts how many times Ctrl-C is pressed and exits after a certain count
 */

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

int count = 0;  // Global variable to keep track of Ctrl-C presses
int max_count = 16;  // The number of times Ctrl-C should be pressed before exiting

void f(int signum)  /* Signal handler */
{
    printf("OUCH!");
    for (int i = 0; i < count; i++) {  // Print the increasing number of exclamation points
        printf("!");
    }
    printf("\n");

    count++;  // increment the count

    if (count >= max_count) {
        exit(0); // exit clean after max count is reached
    }
}

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

    if (argc == 2) {
        max_count = atoi(argv[1]);  // make argv[1] to an integer

    }

    signal( SIGINT, f ); // do f on SIGINT
    // ignore these
    signal( SIGTSTP, SIG_IGN );
    signal( SIGQUIT, SIG_IGN );

    // enter a main loop
    while (1) {
        sleep(1);  // slow down the loop
    }

    return 0;
}