init commit

3sem/seminars/l11/01-2.c

@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+#include <sys/ipc.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int
+main(int argc, char **argv)
+{
+    key_t key = ftok("/dev/null", 0);
+
+    int semid = semget(key, 2, 0666 | IPC_CREAT);
+    int shmid = shmget(key, sizeof(int), 0666 | IPC_CREAT);
+
+    int *shm = shmat(shmid, NULL, 0);
+
+    pid_t pid = fork();
+    if (!pid) {
+        while (scanf("%d", shm) != -1) {
+            semop(semid, &(struct sembuf){.sem_num = 0, .sem_op = 1}, 1);
+
+            semop(semid, &(struct sembuf){.sem_num = 1, .sem_op = -1}, 1);
+        }
+
+        semctl(semid, 2, IPC_RMID, NULL);
+        exit(0);
+    } else if (pid == -1) {
+        exit(1);
+    }
+
+    pid = fork();
+    if (!pid) {
+        for (;;) {
+            if (semop(semid, &(struct sembuf){.sem_num = 0, .sem_op = -1}, 1) == -1) {
+                break;
+            }
+
+            printf("$ %d\n", *shm);
+
+            if (semop(semid, &(struct sembuf){.sem_num = 1, .sem_op = 1}, 1) == -1) {
+                break;
+            }
+        }
+        exit(0);
+    } else if (pid == -1) {
+        exit(1);
+    }
+
+    while (wait(NULL) != -1)
+        ;
+
+    return 0;
+}