lib: multi-heap: Add shared_multi_heap_realloc

Add the function shared_multi_heap_realloc to reallocate memory blocks
in shared multi-heaps.

Signed-off-by: Hubert Guan <hubertyguan@gmail.com>

include/zephyr/multi_heap/shared_multi_heap.h

@@ -176,6 +176,30 @@ void shared_multi_heap_free(void *block);
  */
 int shared_multi_heap_add(struct shared_multi_heap_region *region, void *user_data);
 
+/**
+ * @brief Reallocate memory from the memory shared multi-heap pool
+ *
+ * Returns a pointer to a new memory region with the same contents,
+ * but a different allocated size. If the new allocation can be
+ * expanded in place, the pointer returned will be identical.
+ * Otherwise the data will be copied to a new block and the old one
+ * will be freed as per sys_heap_free(). If the specified size is
+ * smaller than the original, the block will be truncated in place and
+ * the remaining memory returned to the heap. If the allocation of a
+ * new block fails, then NULL will be returned and the old block will
+ * not be freed or modified. The opaque attribute parameter is used
+ * by the backend to select the correct heap to allocate memory from
+ * if needed.
+ *
+ * @param attr		capability / attribute requested for the memory block.
+ * @param ptr		pointer to the memory block to reallocate
+ * @param bytes		requested size of the allocation in bytes.
+ *
+ * @retval newptr	a valid pointer to a new heap memory block of size bytes.
+ * @retval err		NULL if no memory is available.
+ */
+void *shared_multi_heap_realloc(enum shared_multi_heap_attr attr, void *ptr, size_t bytes);
+
 /**
  * @}
  */

lib/heap/shared_multi_heap.c

@@ -91,6 +91,16 @@ void *shared_multi_heap_alloc(enum shared_multi_heap_attr attr, size_t bytes)
 	return sys_multi_heap_alloc(&shared_multi_heap, (void *)(long) attr, bytes);
 }
 
+void *shared_multi_heap_realloc(enum shared_multi_heap_attr attr, void *ptr, size_t bytes)
+{
+	if (attr >= MAX_SHARED_MULTI_HEAP_ATTR) {
+		return NULL;
+	}
+
+	return sys_multi_heap_aligned_realloc(&shared_multi_heap, (void *)(long) attr,
+					      ptr, 0, bytes);
+}
+
 void *shared_multi_heap_aligned_alloc(enum shared_multi_heap_attr attr,
 				      size_t align, size_t bytes)
 {