#include <stdlib.h>
#include <string.h>
#include <sys/ksys.h>
#include "_mem.h"

void* realloc(void* ptr, size_t newsize)
{
    // Handle NULL pointer.
    if (ptr == NULL)
        return NULL;

    // Get a pointer to the mem_node header from the user data pointer.
    struct mem_node* node = GET_MEM_NODE_HEADER(ptr);
    void* new_ptr;

    // If the new size is smaller than or equal to the current size:
    if (node->size >= newsize) {
        // Update the free space in the current node.
        node->free = node->size - newsize;
        // Return the original pointer.
        new_ptr = ptr;
    } else {
        // Allocate a new block of memory with the new size.
        new_ptr = malloc(newsize);

        // If both the old pointer and the new pointer are not NULL:
        if (ptr != NULL && new_ptr != NULL) {
            // Copy the data from the old block to the new block.
            memcpy(new_ptr, ptr, min(newsize, node->size));
            // Free the old block.
            free(ptr);
        }
    }

    // Return the new pointer.
    return new_ptr;
}