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HasanYahya101 · Dec 6, 2024 · 785459c · 785459c
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diff --git a/Lab_14/Question_01/main.c b/Lab_14/Question_01/main.c
@@ -0,0 +1,152 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/sem.h>
+#include <fcntl.h>
+#include <sys/wait.h>
+
+union semun
+{
+    int val;
+    struct semid_ds *buf;
+    unsigned short *array;
+};
+
+int init_semaphores()
+{
+    key_t key = ftok(".", 'S');
+    int semid = semget(key, 2, IPC_CREAT | 0666);
+
+    union semun sem_arg;
+    sem_arg.val = 1;
+    semctl(semid, 0, SETVAL, sem_arg);
+
+    sem_arg.val = 0;
+    semctl(semid, 1, SETVAL, sem_arg);
+
+    return semid;
+}
+
+// P1
+void calc_sum(int semid)
+{
+    struct sembuf sb = {0, -1, 0}; // Wait operation
+    semop(semid, &sb, 1);          // Lock file access
+
+    FILE *file = fopen("numbers.txt", "r+");
+    if (file == NULL)
+    {
+        printf("File opening failed");
+        exit(1);
+    }
+
+    int num, sum = 0;
+    while (fscanf(file, "%d", &num) == 1)
+    {
+        sum += num;
+    }
+
+    // Write sum at the end of file
+    fseek(file, 0, SEEK_END);
+    fprintf(file, "\nSum: %d", sum);
+    fclose(file);
+
+    sb.sem_num = 1;
+    sb.sem_op = 1; // Signal P2 to start
+    semop(semid, &sb, 1);
+
+    printf("P1: Sum calculation completed\n");
+}
+
+// P2
+void count_int(int semid)
+{
+    struct sembuf sb = {1, -1, 0}; // Wait for P1
+    semop(semid, &sb, 1);
+
+    sb.sem_num = 0;
+    sb.sem_op = -1; // Lock file access
+    semop(semid, &sb, 1);
+
+    FILE *file = fopen("numbers.txt", "r+");
+    if (file == NULL)
+    {
+        printf("File opening failed");
+        exit(1);
+    }
+
+    int num, count = 0;
+    while (fscanf(file, "%d", &num) == 1)
+    {
+        count++;
+    }
+
+    fseek(file, 0, SEEK_END);
+    fprintf(file, "\nCount: %d", count);
+    fclose(file);
+
+    sb.sem_num = 1;
+    sb.sem_op = 1; // Signal P3 to start
+    semop(semid, &sb, 1);
+
+    printf("P2: Count calculation completed\n");
+}
+
+// P3
+void calc_avg(int semid)
+{
+    struct sembuf sb = {1, -1, 0}; // Wait for P2
+    semop(semid, &sb, 1);
+
+    FILE *file = fopen("numbers.txt", "r");
+    if (file == NULL)
+    {
+        printf("File opening failed");
+        exit(1);
+    }
+
+    int sum, count;
+    char line[100];
+    while (fgets(line, sizeof(line), file))
+    {
+        if (sscanf(line, "Sum: %d", &sum) == 1)
+            continue;
+        if (sscanf(line, "Count: %d", &count) == 1)
+            break;
+    }
+    fclose(file);
+
+    float average = (float)sum / count;
+    printf("P3: Average = %.2f\n", average);
+
+    semctl(semid, 0, IPC_RMID, 0);
+}
+
+int main()
+{
+    int semid = init_semaphores();
+    pid_t pid1, pid2;
+
+    pid1 = fork();
+    if (pid1 == 0)
+    {
+        calc_sum(semid);
+        exit(0);
+    }
+
+    pid2 = fork();
+    if (pid2 == 0)
+    {
+        count_int(semid);
+        exit(0);
+    }
+
+    calc_avg(semid); // P3
+
+    wait(NULL);
+    wait(NULL);
+
+    return 0;
+}
diff --git a/Lab_14/Question_01/numbers.txt b/Lab_14/Question_01/numbers.txt
@@ -0,0 +1,12 @@
+1
+2
+3
+4
+5
+6
+7
+8
+Sum: 36
+Count: 8
+Sum: 36
+Count: 8
diff --git a/Lab_14/Question_02/main.c b/Lab_14/Question_02/main.c
@@ -0,0 +1,81 @@
+#include <stdio.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+sem_t sem_S1_done;
+sem_t sem_S2_done;
+sem_t log_mutex;
+
+FILE *log_file;
+
+void *service_S1(void *arg)
+{
+    sem_wait(&log_mutex);
+
+    printf("S1: Placing order\n");
+    log_file = fopen("shared_log.txt", "a");
+    fprintf(log_file, "Order ID: 1234, Customer: John Doe\n");
+    fclose(log_file);
+
+    sem_post(&log_mutex);
+    sem_post(&sem_S1_done);
+
+    return NULL;
+}
+
+void *service_S2(void *arg)
+{
+    sem_wait(&sem_S1_done);
+    sem_wait(&log_mutex);
+
+    printf("S2: Processing payment\n");
+    log_file = fopen("shared_log.txt", "a");
+    fprintf(log_file, "Payment Status: Successful\n");
+    fclose(log_file);
+
+    sem_post(&log_mutex);
+    sem_post(&sem_S2_done);
+
+    return NULL;
+}
+
+void *service_S3(void *arg)
+{
+    sem_wait(&sem_S2_done);
+    sem_wait(&log_mutex);
+
+    printf("S3: Confirming order\n");
+    log_file = fopen("shared_log.txt", "a");
+    fprintf(log_file, "Order Confirmation: Confirmed, Timestamp: %ld\n", time(NULL));
+    fclose(log_file);
+
+    sem_post(&log_mutex);
+
+    return NULL;
+}
+
+int main()
+{
+    sem_init(&sem_S1_done, 0, 0);
+    sem_init(&sem_S2_done, 0, 0);
+    sem_init(&log_mutex, 0, 1);
+
+    pthread_t thread_S1, thread_S2, thread_S3;
+
+    pthread_create(&thread_S1, NULL, service_S1, NULL);
+    pthread_create(&thread_S2, NULL, service_S2, NULL);
+    pthread_create(&thread_S3, NULL, service_S3, NULL);
+
+    pthread_join(thread_S1, NULL);
+    pthread_join(thread_S2, NULL);
+    pthread_join(thread_S3, NULL);
+
+    sem_destroy(&sem_S1_done);
+    sem_destroy(&sem_S2_done);
+    sem_destroy(&log_mutex);
+
+    printf("All services completed successfully.\n");
+    return 0;
+}
diff --git a/Lab_14/Question_02/shared_log.txt b/Lab_14/Question_02/shared_log.txt
@@ -0,0 +1,9 @@
+Order ID: 1234, Customer: John Doe
+Payment Status: Successful
+Order Confirmation: Confirmed, Timestamp: 1733469475
+Order ID: 1234, Customer: John Doe
+Payment Status: Successful
+Order Confirmation: Confirmed, Timestamp: 1733469594
+Order ID: 1234, Customer: John Doe
+Payment Status: Successful
+Order Confirmation: Confirmed, Timestamp: 1733469612