63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
/* 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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/* This program illustrates that calls made from
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* within a signal handler may have an effect on the
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* world outside the signal handler.
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*
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* Specifically, using buffered I/O will interfere
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* with buffered I/O outside of the signal handler,
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* similar to what we've seen when we looked at how
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* fork(2) copies the output buffer.
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*/
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#include <err.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 <string.h>
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#include <unistd.h>
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#ifndef SLEEP
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#define SLEEP 5
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#endif
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#define MSG "SIGQUIT caught.\n"
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static void
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sig_quit(int signo) {
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(void)signo;
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//(void)printf(MSG);
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(void)write(STDOUT_FILENO, MSG, strlen(MSG));
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}
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int
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main(int argc, char **argv) {
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(void)argv;
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if (signal(SIGQUIT, sig_quit) == SIG_ERR) {
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err(EXIT_FAILURE, "unable to set SIGQUIT signal handler");
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/* NOTREACHED */
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}
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(void)printf("=> Waiting for a signal...");
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if (argc > 1) {
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pause();
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}
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(void)printf(" done.\n");
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exit(EXIT_SUCCESS);
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}
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