65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
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/* This file is part of the sample code and exercises
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* used by the class "Advanced Programming in the UNIX
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* Environment" taught by Jan Schaumann
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* <jschauma@netmeister.org> at Stevens Institute of
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* Technology.
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*
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* This file is in the public domain.
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*
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* You don't have to, but if you feel like
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* acknowledging where you got this code, you may
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* reference me by name, email address, or point
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* people to the course website:
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* https://stevens.netmeister.org/631/
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*/
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/* A simple program illustrating the implementation of a signal handler.
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* Note that we can use the same signal handler for multiple different
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* signals.
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*/
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#include <err.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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static void
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sig_usr(int signo) {
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if (signo == SIGUSR1)
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(void)printf("Nobody expects SIGUSR1!\n");
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else if (signo == SIGUSR2)
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(void)printf("A surprising turn of events occurred!\n");
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else {
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(void)fprintf(stderr, "received signal: %d\n", signo);
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exit(EXIT_FAILURE);
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}
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return;
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}
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int
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main(void) {
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if (signal(SIGUSR1, sig_usr) == SIG_ERR) {
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err(EXIT_FAILURE, "unable to catch SIGUSR1");
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/* NOTREACHED */
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}
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if (signal(SIGUSR2, sig_usr) == SIG_ERR) {
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err(EXIT_FAILURE, "unable to catch SIGUSR2");
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/* NOTREACHED */
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}
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if (signal(SIGHUP, sig_usr) == SIG_ERR) {
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err(EXIT_FAILURE, "unable to catch SIGHUP");
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/* NOTREACHED */
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}
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(void)printf("%d\n", getpid());
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for ( ; ; ) {
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pause();
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/* Note that the compiler is smart enough to realize we
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* don't return from main, so won't warn that we didn't
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* return a value. */
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}
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}
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