int main(int argc, char *argv[]) {
struct sigaction sa;
sigset_t prevMask, blockMask, pendingMask;
printf("%s: PID is %ld\n", argv[0], (long) getpid());
sa.sa_handler = sigcont_handler;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
if (sigaction(SIGCONT, &sa, NULL) == -1)
errExit("sigaction error");
if (sigaction(SIGUSR1, &sa, NULL) == -1)
errExit("sigaction error");
sigemptyset(&blockMask);
sigaddset(&blockMask, SIGCONT);
sigaddset(&blockMask, SIGUSR1);
printf("Start blocking SIGCONT & SIGUSR1\n");
if (sigprocmask(SIG_SETMASK, &blockMask, &prevMask) == -1)
errExit("sigprocmask error");
printf("Start sleeping ...\n");
sleep(10);
printf("Stop sleeping ...\n");
if (sigpending(&pendingMask) == -1)
errExit("sigpending");
printf("%s: pending signals are: \n", argv[0]);
printSigset(stdout, "\t\t", &pendingMask);
printf("Stop blocking SIGCONT & SIGUSR1\n");
if (sigprocmask(SIG_SETMASK, &prevMask, NULL) == -1)
errExit("sigprocmask error");
if (sigpending(&pendingMask) == -1)
errExit("sigpending");
printf("%s: pending signals are: \n", argv[0]);
printSigset(stdout, "\t\t", &pendingMask);
exit(EXIT_SUCCESS);
}
int
main(int argc, char *argv[])
{
int n, numSecs;
sigset_t pendingMask, blockingMask, emptyMask;
printf("%s: PID is %ld\n", argv[0], (long) getpid());
/* Here we use the simpler signal() API to establish a signal handler,
but for the reasons described in Section 22.7 of TLPI, sigaction()
is the (strongly) preferred API for this task. */
for (n = 1; n < NSIG; n++) /* Same handler for all signals */
(void) signal(n, handler); /* Ignore errors */
/* If a sleep time was specified, temporarily block all signals,
sleep (while another process sends us signals), and then
display the mask of pending signals and unblock all signals */
if (argc > 1) {
numSecs = getInt(argv[1], GN_GT_0, NULL);
sigfillset(&blockingMask);
if (sigprocmask(SIG_SETMASK, &blockingMask, NULL) == -1)
errExit("sigprocmask");
printf("%s: sleeping for %d seconds\n", argv[0], numSecs);
sleep(numSecs);
if (sigpending(&pendingMask) == -1)
errExit("sigpending");
printf("%s: pending signals are: \n", argv[0]);
printSigset(stdout, "\t\t", &pendingMask);
sigemptyset(&emptyMask); /* Unblock all signals */
if (sigprocmask(SIG_SETMASK, &emptyMask, NULL) == -1)
errExit("sigprocmask");
}
while (!gotSigint) /* Loop until SIGINT caught */
continue;
for (n = 1; n < NSIG; n++) /* Display number of signals received */
if (sigCnt[n] != 0)
printf("%s: signal %d caught %d time%s\n", argv[0], n,
sigCnt[n], (sigCnt[n] == 1) ? "" : "s");
exit(EXIT_SUCCESS);
}
int /* Print signals currently pending for this process */
printPendingSigs(FILE *of, const char *msg)
{
sigset_t pendingSigs;
if (msg != NULL)
fprintf(of, "%s", msg);
if (sigpending(&pendingSigs) == -1)
return -1;
printSigset(of, "\t\t", &pendingSigs);
return 0;
}
int /* Print mask of blocked signals for this process */
printSigMask(FILE *of, const char *msg)
{
sigset_t currMask;
if (msg != NULL)
fprintf(of, "%s", msg);
if (sigprocmask(SIG_BLOCK, NULL, &currMask) == -1)
return -1;
printSigset(of, "\t\t", &currMask);
return 0;
}
int
printPendingSigs(FILE *of, const char *msg)
{
sigset_t pendingSigs;
if (msg != NULL)
fprintf(of, "%s", msg);
if (sigpending(&pendingSigs) == -1)
return -1;
printSigset(of, "\t\t", &pendingSigs);
return 0;
}
int
printSigMask(FILE *of, const char *msg)
{
sigset_t currMask;
if (msg != NULL)
fprintf(of, "%s", msg);
if (sigprocmask(SIG_BLOCK, NULL, &currMask) == -1)
return -1;
printSigset(of, "\t\t", &currMask);
return 0;
}
int
main(int argc, char *argv[])
{
sigset_t pending, blocked;
const int numSecs = 5;
struct sigaction sa;
/* Set up a handler for SIGINT */
printf("Setting up handler for SIGINT\n");
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sa.sa_handler = handler;
if (sigaction(SIGINT, &sa, NULL) == -1)
errExit("sigaction");
/* Block SIGINT for a while */
sigemptyset(&blocked);
sigaddset(&blocked, SIGINT);
if (sigprocmask(SIG_SETMASK, &blocked, NULL) == -1)
errExit("sigprocmask");
printf("BLOCKING SIGINT for %d seconds\n", numSecs);
sleep(numSecs);
/* Display mask of pending signals */
if (sigpending(&pending) == -1)
errExit("sigpending");
printf("PENDING signals are: \n");
printSigset(stdout, "\t\t", &pending);
/* Now ignore SIGINT */
sleep(2);
printf("Ignoring SIGINT\n");
if (signal(SIGINT, SIG_IGN) == SIG_ERR)
errExit("signal");
/* Redisplay mask of pending signals */
if (sigpending(&pending) == -1)
errExit("sigpending");
if (sigismember(&pending, SIGINT)) {
printf("SIGINT is now pending\n");
} else {
printf("PENDING signals are: \n");
printSigset(stdout, "\t\t", &pending);
}
sleep(2);
/* Reestablish SIGINT handler */
printf("Reestablishing handler for SIGINT\n");
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sa.sa_handler = handler;
if (sigaction(SIGINT, &sa, NULL) == -1)
errExit("sigaction");
sleep(2);
/* And unblock SIGINT */
printf("UNBLOCKING SIGINT\n");
sigemptyset(&blocked);
if (sigprocmask(SIG_SETMASK, &blocked, NULL) == -1)
errExit("sigprocmask");
exit(EXIT_SUCCESS);
}
