57 lines
1.2 KiB
C
Executable File
57 lines
1.2 KiB
C
Executable File
#include <stdio.h>
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#include <sys/types.h>
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#include <sys/sem.h>
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#include <sys/shm.h>
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#include <sys/ipc.h>
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#include <stdlib.h>
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#include <sys/wait.h>
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#include <unistd.h>
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int
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main(int argc, char **argv)
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{
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key_t key = ftok("/dev/null", 0);
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int semid = semget(key, 2, 0666 | IPC_CREAT);
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int shmid = shmget(key, sizeof(int), 0666 | IPC_CREAT);
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int *shm = shmat(shmid, NULL, 0);
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pid_t pid = fork();
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if (!pid) {
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while (scanf("%d", shm) != -1) {
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semop(semid, &(struct sembuf){.sem_num = 0, .sem_op = 1}, 1);
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semop(semid, &(struct sembuf){.sem_num = 1, .sem_op = -1}, 1);
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}
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semctl(semid, 2, IPC_RMID, NULL);
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exit(0);
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} else if (pid == -1) {
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exit(1);
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}
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pid = fork();
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if (!pid) {
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for (;;) {
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if (semop(semid, &(struct sembuf){.sem_num = 0, .sem_op = -1}, 1) == -1) {
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break;
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}
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printf("$ %d\n", *shm);
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if (semop(semid, &(struct sembuf){.sem_num = 1, .sem_op = 1}, 1) == -1) {
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break;
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}
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}
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exit(0);
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} else if (pid == -1) {
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exit(1);
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}
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while (wait(NULL) != -1)
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;
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return 0;
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}
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