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// Program 8.1
#include <math.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc, char *argv[]) {
int i;
sigset_t intmask;
int repeatfactor;
double y = 0.0;
if (argc != 2) {
fprintf(stderr, "Usage: %s repeatfactor\n", argv[0]);
return 1;
}
repeatfactor = atoi(argv[1]);
if ((sigemptyset(&intmask) == -1) || (sigaddset(&intmask, SIGINT) == -1)){
perror("Failed to initialize the signal mask");
return 1;
}
for ( ; ; ) {
if (sigprocmask(SIG_BLOCK, &intmask, NULL) == -1)
break;
fprintf(stderr, "SIGINT signal blocked\n");
for (i = 0; i < repeatfactor; i++)
y += sin((double)i);
fprintf(stderr, "Blocked calculation is finished, y = %f\n", y);
sleep(3);
if (sigprocmask(SIG_UNBLOCK, &intmask, NULL) == -1)
break;
fprintf(stderr, "SIGINT signal unblocked\n");
for (i = 0; i < repeatfactor; i++)
y += sin((double)i);
fprintf(stderr, "Unblocked calculation is finished, y=%f\n", y);
sleep(3);
}
perror("Failed to change signal mask");
return 1;
}
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