path: root / Year 3 / System programming / Practice11 / ex3-1.c


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#include <unistd.h>
#include <stdio.h>
#include <semaphore.h>
#include <sys/stat.h>
#include <fcntl.h>

int main() {
	sem_t* sem1 = sem_open("/sem1", O_CREAT, 0755, 0);
	sem_t* sem2 = sem_open("/sem2", O_CREAT, 0755, 0);

	int fd = open("test.txt", O_WRONLY | O_CREAT, 0755);

	while (1) {
		sleep(1);

		lseek(fd, 0, SEEK_END);
		write(fd, "(1)", 3);
		printf("written\n");

		sem_post(sem2);
		sem_wait(sem1);
	}

	close(fd);
	sem_close(sem1);
	sem_close(sem2);
	sem_unlink("/sem1");

	return 0;
}