fix writing to the queue using the same value

the fix was to memcpy the passed pointer to a local one and it works :-)

lab01/zad1/include/queue.h

@@ -6,7 +6,7 @@
 
 typedef struct Queue Queue;
 
-Queue *queue_new(size_t size);
+Queue *queue_new(size_t size, size_t element_size);
 
 void *queue_read(Queue *queue);
 

lab01/zad1/src/main.c

@@ -7,7 +7,7 @@
 int main(void) {
     srand((unsigned int)time(NULL));
     
-    Queue *q = queue_new(51);
+    Queue *q = queue_new(51, sizeof(long));
 
     for (size_t i = 0; i < 50; ++i) {
         long val = rand() % 1000;

lab01/zad1/src/queue.c

@@ -1,19 +1,22 @@
 #include <queue.h>
 
 #include <stdlib.h>
+#include <string.h>
 
 struct Queue {
     size_t back;
     size_t front;
     size_t size;
+    size_t element_size;
     void **data;
 };
 
-Queue *queue_new(size_t size) {
+Queue *queue_new(size_t size, size_t element_size) {
     Queue *ret = malloc(sizeof(Queue));
     ret->back = 0;
     ret->front = 0;
     ret->size = size;
+    ret->element_size = element_size;
     ret->data = malloc(size * sizeof(void*));
 
     return ret;
@@ -36,7 +39,8 @@ bool queue_write(Queue *q, void *value) {
         return false;
     }
 
-    q->data[q->back] = value;
+    void *local_value = memcpy(malloc(q->element_size), value, q->element_size);
+    q->data[q->back] = local_value;
     q->back = (q->back + 1) % q->size;
 
     return true;