kernel: implement k_realloc

implement k_realloc.

Signed-off-by: Fin Maaß <f.maass@vogl-electronic.com>

include/zephyr/kernel.h

@@ -5381,6 +5381,32 @@ void *k_heap_aligned_alloc(struct k_heap *h, size_t align, size_t bytes,
 void *k_heap_alloc(struct k_heap *h, size_t bytes,
 		k_timeout_t timeout) __attribute_nonnull(1);
 
+/**
+ * @brief Reallocate memory from a k_heap
+ *
+ * Reallocates and returns a memory buffer from the memory region owned
+ * by the heap.  If no memory is available immediately, the call will
+ * block for the specified timeout (constructed via the standard
+ * timeout API, or K_NO_WAIT or K_FOREVER) waiting for memory to be
+ * freed.  If the allocation cannot be performed by the expiration of
+ * the timeout, NULL will be returned.
+ * Reallocated memory is aligned on a multiple of pointer sizes.
+ *
+ * @note @a timeout must be set to K_NO_WAIT if called from ISR.
+ * @note When CONFIG_MULTITHREADING=n any @a timeout is treated as K_NO_WAIT.
+ *
+ * @funcprops \isr_ok
+ *
+ * @param h Heap from which to allocate
+ * @param ptr Original pointer returned from a previous allocation
+ * @param bytes Desired size of block to allocate
+ * @param timeout How long to wait, or K_NO_WAIT
+ *
+ * @return Pointer to memory the caller can now use, or NULL
+ */
+void *k_heap_realloc(struct k_heap *h, void *ptr, size_t bytes, k_timeout_t timeout)
+	__attribute_nonnull(1);
+
 /**
  * @brief Free memory allocated by k_heap_alloc()
  *
@@ -5528,6 +5554,25 @@ void k_free(void *ptr);
  */
 void *k_calloc(size_t nmemb, size_t size);
 
+/** @brief Expand the size of an existing allocation
+ *
+ * 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 copies 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.
+ *
+ * @param ptr Original pointer returned from a previous allocation
+ * @param size Amount of memory requested (in bytes).
+ *
+ * @return Pointer to memory the caller can now use, or NULL.
+ */
+void *k_realloc(void *ptr, size_t size);
+
 /** @} */
 
 /* polling API - PRIVATE */

kernel/kheap.c

@@ -116,6 +116,32 @@ void *k_heap_alloc(struct k_heap *heap, size_t bytes, k_timeout_t timeout)
 	return ret;
 }
 
+void *k_heap_realloc(struct k_heap *heap, void *ptr, size_t bytes, k_timeout_t timeout)
+{
+	k_timepoint_t end = sys_timepoint_calc(timeout);
+	void *ret = NULL;
+
+	k_spinlock_key_t key = k_spin_lock(&heap->lock);
+
+	__ASSERT(!arch_is_in_isr() || K_TIMEOUT_EQ(timeout, K_NO_WAIT), "");
+
+	while (ret == NULL) {
+		ret = sys_heap_aligned_realloc(&heap->heap, ptr, sizeof(void *), bytes);
+
+		if (!IS_ENABLED(CONFIG_MULTITHREADING) ||
+		    (ret != NULL) || K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
+			break;
+		}
+
+		timeout = sys_timepoint_timeout(end);
+		(void) z_pend_curr(&heap->lock, key, &heap->wait_q, timeout);
+		key = k_spin_lock(&heap->lock);
+	}
+
+	k_spin_unlock(&heap->lock, key);
+	return ret;
+}
+
 void k_heap_free(struct k_heap *heap, void *mem)
 {
 	k_spinlock_key_t key = k_spin_lock(&heap->lock);

kernel/mempool.c

@@ -113,6 +113,34 @@ void *k_calloc(size_t nmemb, size_t size)
 	return ret;
 }
 
+void *k_realloc(void *ptr, size_t size)
+{
+	struct k_heap *heap, **heap_ref;
+	void *ret;
+
+	if (size == 0) {
+		k_free(ptr);
+		return NULL;
+	}
+	if (ptr == NULL) {
+		return k_malloc(size);
+	}
+	heap_ref = ptr;
+	ptr = --heap_ref;
+	heap = *heap_ref;
+
+	if (size_add_overflow(size, sizeof(heap_ref), &size)) {
+		return NULL;
+	}
+
+	ret = k_heap_realloc(heap, ptr, size, K_NO_WAIT);
+	if (ret != NULL) {
+		heap_ref = ret;
+		ret = ++heap_ref;
+	}
+	return ret;
+}
+
 void k_thread_system_pool_assign(struct k_thread *thread)
 {
 	thread->resource_pool = _SYSTEM_HEAP;