Shared memory and semaphore setup

supervisor.c

@@ -9,6 +9,8 @@
 
 static const char *pname;
 
+struct circ_buf *shared;
+
 struct sigaction sa;
 
 static volatile sig_atomic_t quit = 0;
@@ -25,6 +27,40 @@ void usage(void)
 	exit(EXIT_FAILURE);
 }
 
+void initCircBuf()
+{
+	shared->validItems = 0;
+	shared->head = 0;
+	shared->tail = 0;
+	shared->quit = 0;
+	for (int i = 0; i < MAX_ITEMS; i++) {
+		shared->data[i] = 0;
+	}
+	return;
+}
+
+int isEmpty()
+{
+	if (shared->validItems == 0)
+		return 1;
+	else
+		return 0;
+}
+
+int getItem()
+{
+	if (isEmpty())
+		return -1;
+	
+	int value;
+	
+	value = shared->data[shared->head];
+	shared->head = (shared->head + 1) % MAX_ITEMS;
+	shared->validItems--;
+
+	return value;
+}
+
 int main(int argc, char *argv[])
 {
 	if (argc != 1)
@@ -37,7 +73,29 @@ int main(int argc, char *argv[])
 	sigaction(SIGINT, &sa, NULL);
 	sigaction(SIGTERM, &sa, NULL);
 
+	int shmfd = shm_open(SHM_NAME, O_RDWR | O_CREAT, PERMISSION);
+	if (shmfd == -1) {
+		perror(pname);
+		exit(EXIT_FAILURE);
+	}
+	if (ftruncate(shmfd, sizeof(*shared)) == -1) {
+		perror(pname);
+		exit(EXIT_FAILURE);
+	}
+
+	shared = mmap(NULL, sizeof(*shared), PROT_READ | PROT_WRITE, MAP_SHARED, shmfd, 0);
+	if (shared == MAP_FAILED) {
+		perror(pname);
+		exit(EXIT_FAILURE);
+	}
+
+	sem_t *sFreeSpace = sem_open(SEM_FREE_SPACE, O_CREAT | O_EXCL, PERMISSION, MAX_ITEMS);
+	sem_t *sUsedSpace = sem_open(SEM_USED_SPACE, O_CREAT | O_EXCL, PERMISSION, 0);
+
+	initCircBuf();
+
 	while (quit == 0) {
+		
 
 	}