From cedb5d607c771f13b37018734910335be82eff8e Mon Sep 17 00:00:00 2001
From: Godmar Back <gback@cs.vt.edu>
Date: Fri, 28 Oct 2022 13:46:39 -0400
Subject: [PATCH] properly check for return value of mem_sbrk

---
 mm-gback-implicit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm-gback-implicit.c b/mm-gback-implicit.c
index b35fdeb..1e64989 100644
--- a/mm-gback-implicit.c
+++ b/mm-gback-implicit.c
@@ -145,7 +145,7 @@ int mm_init(void)
 
     /* Create the initial empty heap */
     struct boundary_tag * initial = mem_sbrk(4 * sizeof(struct boundary_tag));
-    if (initial == (void *)-1)
+    if (initial == NULL)
         return -1;
 
     /* We use a slightly different strategy than suggested in the book.
@@ -302,7 +302,7 @@ static struct block *extend_heap(size_t words)
 {
     void *bp = mem_sbrk(words * WSIZE);
 
-    if ((intptr_t) bp == -1)
+    if (bp == NULL)
         return NULL;
 
     /* Initialize free block header/footer and the epilogue header.