No need to use ptr pointer, set previous node to null for head only if it exists.

src/linked_lists/search_algorithms.c

@@ -15,6 +15,7 @@
  *
  */
 
+#include <stdio.h>
 #include "linked_lists/search_algorithms.h"
 #include "block_header.h"
 
@@ -59,13 +60,12 @@ void * search_on_fixed(heap_t * heap, size_t requested_size) {
  * found.
  */
 void * best_fit_on_freelist(heap_t *heap, size_t requested_size) {
-    void *current_block, *previous_block, *ptr;
+    void *current_block, *previous_block;
     void *best_block, *best_previous_block;
     size_t best_size;
 
     previous_block = NULL;
     best_previous_block = NULL;
-    ptr = NULL;
     best_block = NULL;
     best_size = (size_t) -1; /* SIZE_MAX */
 
@@ -76,6 +76,8 @@ void * best_fit_on_freelist(heap_t *heap, size_t requested_size) {
                 best_block = current_block;
                 best_size = get_size(current_block);
                 best_previous_block = previous_block;
+                /* If the requested size is found, there is no need to keep
+                 * searching for a better sized block */
                 if(best_size == requested_size) {
                     break;
                 }
@@ -90,7 +92,9 @@ void * best_fit_on_freelist(heap_t *heap, size_t requested_size) {
         if(best_block == heap->free_list_head) {
             heap->free_list_head = get_next(best_block);
 #ifdef BLOCKS_IN_DLL
-            set_previous(heap->free_list_head, NULL);
+            if(heap->free_list_head != NULL) {
+                set_previous(heap->free_list_head, NULL);
+            }
 #endif /* BLOCKS_IN_DLL */
         } else {
             set_next(best_previous_block, get_next(best_block));
@@ -98,10 +102,9 @@ void * best_fit_on_freelist(heap_t *heap, size_t requested_size) {
             set_previous(get_next(best_block), best_previous_block);
 #endif /* BLOCKS_IN_DLL */
         }
-        ptr = best_block;
     }
 
-    return ptr;
+    return best_block;
 }
 
 /**