#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <semaphore.h>
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#include <time.h>
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#include <assert.h>
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#include <errno.h>
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#include <signal.h>
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sem_t sem;
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#define handle_error(msg) \
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do { perror(msg); exit(EXIT_FAILURE); } while (0)
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static void
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handler(int sig)
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{
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puts("sig handler\n");
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// write(STDOUT_FILENO, "sem_post() from handler\n", 24);
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// if (sem_post(&sem) == -1)
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// {
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// write(STDERR_FILENO, "sem_post() failed\n", 18);
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// _exit(EXIT_FAILURE);
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// }
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}
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int
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main(int argc, char *argv[])
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{
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struct sigaction sa;
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struct timespec ts;
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int s;
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if (sem_init(&sem, 0, 0) == -1)
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handle_error("sem_init");
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/* Establish SIGALRM handler; set alarm timer using argv[1] */
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sa.sa_handler = handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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if (sigaction(SIGINT, &sa, NULL) == -1)
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handle_error("sigaction");
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/* Calculate relative interval as current time plus
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number of seconds given argv[2] */
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if (clock_gettime(CLOCK_REALTIME, &ts) == -1)
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handle_error("clock_gettime");
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ts.tv_sec += atoi(argv[2]);
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printf("main() about to call sem_wait()\n");
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while ((s = sem_wait(&sem)) == -1 )
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printf("%d , %d\n", errno, errno == EINTR);
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}
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