Implement message send and receive functions.

programs/tests/CMakeLists.txt

@@ -88,6 +88,8 @@ set(TESTS
     t_semget.c
     t_semflg.c
     t_semop.c
+    # Test message queues.
+    t_msgget.c
     # Test scheduling feedback tests.
     t_schedfb.c
 )

programs/tests/t_msgget.c

@@ -0,0 +1,81 @@
+/// @file t_msgget.c
+/// @brief This program creates a message queue.
+/// @copyright (c) 2014-2023 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include "string.h"
+#include "sys/unistd.h"
+#include "sys/errno.h"
+#include "sys/msg.h"
+#include "sys/ipc.h"
+#include "stdlib.h"
+#include "fcntl.h"
+#include "stdio.h"
+
+#define MESSAGE_LEN 100
+
+// structure for message queue
+typedef struct {
+    long mesg_type;
+    char mesg_text[MESSAGE_LEN];
+} message_t;
+
+int main(int argc, char *argv[])
+{
+    message_t message;
+    long ret, msqid;
+    key_t key;
+
+    // ========================================================================
+    // Generating a key using ftok
+    key = ftok("/home/user/test7.txt", 5);
+    if (key < 0) {
+        perror("Failed to generate key using ftok");
+        return 1;
+    }
+    printf("Generated key using ftok (key = %d)\n", key);
+
+    // ========================================================================
+    // Create the first message queue.
+    msqid = msgget(key, IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
+    if (msqid < 0) {
+        perror("Failed to create message queue");
+        return 1;
+    }
+    printf("Created message queue (id : %d)\n", msqid);
+
+    // Set the type.
+    message.mesg_type = 1;
+    // Set the content.
+    strcpy(message.mesg_text, "Hello there!");
+
+    // Send the message.
+    if (msgsnd(msqid, &message, sizeof(message), 0) < 0) {
+        perror("Failed to send the message");
+        return 1;
+    }
+    // Display the message.
+    printf("We sent the message `%s`\n", message.mesg_text);
+
+    // Clear the user-defined message.
+    memset(message.mesg_text, 0, sizeof(char) * MESSAGE_LEN);
+    // Receive the message.
+    if (msgrcv(msqid, &message, sizeof(message), 1, 0) < 0) {
+        perror("Failed to receive the message");
+        return 1;
+    }
+    // Display the message.
+    printf("We received the message `%s`\n", message.mesg_text);
+
+    // Clear the user-defined message.
+    memset(message.mesg_text, 0, sizeof(char) * MESSAGE_LEN);
+    // Receive the message.
+    if (msgrcv(msqid, &message, sizeof(message), 1, 0) < 0) {
+        perror("Failed to receive the message");
+        return 1;
+    }
+    // Display the message.
+    printf("We received the message `%s`\n", message.mesg_text);
+
+    return 0;
+}