Finshed up the regex backend

src/system_allocator.c

@@ -1,16 +1,27 @@
+#include <string.h>
 #include <stdlib.h>
 #include "internal.h"
 
 static void* system_alloc(HAllocator *allocator, size_t size) {
-  return malloc(size);
+  
+  void* ptr = calloc(size + sizeof(size_t), 1);
+  *(size_t*)ptr = size;
+  return ptr + sizeof(size_t);
 }
 
 static void* system_realloc(HAllocator *allocator, void* ptr, size_t size) {
-  return realloc(ptr, size);
+  if (ptr == NULL)
+    return system_alloc(allocator, size);
+  ptr = realloc(ptr - sizeof(size_t), size + sizeof(size_t));
+  size_t old_size = *(size_t*)ptr;
+  *(size_t*)ptr = size;
+  if (size > old_size)
+    memset(ptr+sizeof(size_t)+old_size, 0, size - old_size);
+  return ptr + sizeof(size_t);
 }
 
 static void system_free(HAllocator *allocator, void* ptr) {
-  free(ptr);
+  free(ptr - sizeof(size_t));
 }
 
 HAllocator system_allocator = {