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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
// Define the message structure
struct message {
long mtype; // Message Type
char mtext[100]; // Message body
};
struct timespec ts = {
.tv_sec = 3468960000, // 2075-12-05 Destination timestamp
.tv_nsec = 0
};
void print_msqid_ds(struct msqid_ds *buf) {
printf("perms: %o\n", buf->msg_perm.mode);
printf("UID: %d\n", buf->msg_perm.uid);
printf("GID: %d\n", buf->msg_perm.gid);
printf("Current number of bytes in the queue: %d\n", buf->msg_cbytes);
printf("Number of messages in the queue: %d\n", buf->msg_qnum);
printf("Maximum number of bytes allowed in the queue: %d\n", buf->msg_qbytes);
printf("Last sent time: %s", buf->msg_stime ? ctime(&buf->msg_stime) + 4 : "Not set \n");
printf("Last received time: %s", buf->msg_rtime ? ctime(&buf->msg_rtime) + 4 : "Not set \n");
}
int main() {
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;
}
key_t key = ftok(".", 123);
if (key == -1) {
perror("ftok");
return 1;
}
int msqid = msgget(key, 0644 | IPC_CREAT); // Set to write/read only (not full permissions)
if (msqid == -1) {
perror("msgget");
return 1;
}
// Get message queue status
struct msqid_ds buf;
memset(&buf, 0, sizeof(buf)); // Clear the structure
if (msgctl(msqid, IPC_STAT, &buf) == -1) {
perror("msgctl");
return 1;
}
// Print message queue information
printf("=== Initial queue status ===\n");
printf("key: %x\n", key);
printf("msqid: %d\n", msqid);
print_msqid_ds(&buf);
// Prepare the message to be sent
struct message msg = {0};
msg.mtype = 1; // Set the message type to 1
int i =0;
for(i =0; i< 2; i++)
{
snprintf(msg.mtext, sizeof(msg.mtext), "Hello, Message Queue %d!", i);
msg.mtext[sizeof(msg.mtext) - 1] = '\0'; // Ensure the message ends with a '\0'
// Send the message
if (msgsnd(msqid, &msg, strlen(msg.mtext) + 1, 0) == -1) {
perror("msgsnd");
return 1;
}
printf("Message sent: %s\n", msg.mtext);
// Check the queue status again
memset(&buf, 0, sizeof(buf)); // Clear the structure
if (msgctl(msqid, IPC_STAT, &buf) == -1) {
perror("msgctl");
return 1;
}
printf("\n=== Queue status after the message is sent ===\n");
print_msqid_ds(&buf);
}
// Change permissions
buf.msg_perm.mode = 0600; // New permissions
if (msgctl(msqid, IPC_SET, &buf) == -1) {
perror("msgctl IPC_SET failed");
msgctl(msqid, IPC_RMID, NULL);
exit(EXIT_FAILURE);
}
if ((buf.msg_stime - ts.tv_sec > 60) || (ts.tv_sec - buf.msg_stime > 60)) {
printf("\nMsgctl get a error time! \n");
exit(EXIT_FAILURE);
}
msgctl(msqid, IPC_RMID, NULL);
// 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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