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#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <time.h>
#include <unistd.h>
union semun {
int val;
struct semid_ds *buf;
unsigned short *array;
};
struct timespec ts = {
.tv_sec = 3468960000, // 3468960000 2075-12-05 Destination timestamp
.tv_nsec = 0
};
void print_semid_ds(struct semid_ds *ds) {
printf("sem_perm.uid: %d\n", ds->sem_perm.uid);
printf("sem_perm.gid: %d\n", ds->sem_perm.gid);
printf("sem_perm.cuid: %d\n", ds->sem_perm.cuid);
printf("sem_perm.cgid: %d\n", ds->sem_perm.cgid);
printf("sem_perm.mode: %o\n", ds->sem_perm.mode);
printf("sem_nsems: %d\n", ds->sem_nsems);
printf("sem_otime: %s", ctime(&ds->sem_otime));
printf("sem_ctime: %s \n", ctime(&ds->sem_ctime));
}
int main() {
int semid;
union semun arg;
struct semid_ds ds;
struct timespec ts_init, ts_final;
// Save system time
if (clock_gettime(CLOCK_REALTIME, &ts_init) == -1) {
perror("Error getting time");
return 1;
}
if (clock_settime(CLOCK_REALTIME, &ts) == -1) { // Set the time to after 2038
perror("Error setting time");
return 1;
}
// Create a semaphore set
if ((semid = semget(IPC_PRIVATE, 1, 0666 | IPC_CREAT)) == -1) {
perror("semget failed");
exit(1);
}
// Get the semid_ds structure
arg.buf = &ds;
if (semctl(semid, 0, IPC_STAT, arg) == -1) {
perror("semctl IPC_STAT failed");
exit(1);
}
// Print the structure contents
printf("=== semid_ds structure values ===\n");
print_semid_ds(&ds);
// Change permissions
ds.sem_perm.mode = 0600; // Change to new permissions
if (semctl(semid, 0, IPC_SET, arg) == -1) {
perror("semctl IPC_SET failed");
semctl(semid, 0, IPC_RMID);
exit(EXIT_FAILURE);
}
// Print the structure contents
printf("=== semid_ds structure values ===\n");
print_semid_ds(&ds);
if ((ds.sem_ctime - ts.tv_sec > 60) || (ts.tv_sec - ds.sem_ctime > 60)) {
printf("\nSemctl get a error time! \n");
exit(EXIT_FAILURE);
}
// Delete a semaphore
if (semctl(semid, 0, IPC_RMID) == -1) {
perror("semctl IPC_RMID failed");
exit(1);
}
// Restore system time
clock_gettime(CLOCK_REALTIME, &ts_final);
ts_init.tv_sec = ts_init.tv_sec + ts_final.tv_sec - ts.tv_sec;
clock_settime(CLOCK_REALTIME, &ts_init);
return 0;
}
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