Handle zero NEW_SIZE case.

libc/stdlib/malloc/realloc.c

@@ -21,60 +21,69 @@
 void *
 realloc (void *mem, size_t new_size)
 {
-  if (! mem)
-    return malloc (new_size);
-  else
+  size_t size;
+  char *base_mem;
+
+  /* Check for special cases.  */
+  if (! new_size)
     {
-      char *base_mem = MALLOC_BASE (mem);
-      size_t size = MALLOC_SIZE (mem);
+      free (mem);
+      return 0;
+    }
+  else if (! mem)
+    return malloc (new_size);
 
-      /* Include extra space to record the size of the allocated block.
-	 Also make sure that we're dealing in a multiple of the heap
-	 allocation unit (SIZE is already guaranteed to be so).*/
-      new_size = HEAP_ADJUST_SIZE (new_size + MALLOC_HEADER_SIZE);
+  /* Normal realloc.  */
 
-      MALLOC_DEBUG ("realloc: 0x%lx, %d (base = 0x%lx, total_size = %d)\n",
-		    (long)mem, new_size, (long)base_mem, size);
+  base_mem = MALLOC_BASE (mem);
+  size = MALLOC_SIZE (mem);
 
-      if (new_size > size)
-	/* Grow the block.  */
-	{
-	  size_t extra = new_size - size;
+  /* Include extra space to record the size of the allocated block.
+     Also make sure that we're dealing in a multiple of the heap
+     allocation unit (SIZE is already guaranteed to be so).*/
+  new_size = HEAP_ADJUST_SIZE (new_size + MALLOC_HEADER_SIZE);
+
+  MALLOC_DEBUG ("realloc: 0x%lx, %d (base = 0x%lx, total_size = %d)\n",
+		(long)mem, new_size, (long)base_mem, size);
+
+  if (new_size > size)
+    /* Grow the block.  */
+    {
+      size_t extra = new_size - size;
 
-	  __malloc_lock ();
-	  extra = __heap_alloc_at (&__malloc_heap, base_mem + size, extra);
-	  __malloc_unlock ();
+      __malloc_lock ();
+      extra = __heap_alloc_at (&__malloc_heap, base_mem + size, extra);
+      __malloc_unlock ();
 
-	  if (extra)
-	    /* Record the changed size.  */
-	    MALLOC_SET_SIZE (mem, new_size);
-	  else
-	    /* Our attempts to extend MEM in place failed, just
-	       allocate-and-copy.  */
+      if (extra)
+	/* Record the changed size.  */
+	MALLOC_SET_SIZE (mem, new_size);
+      else
+	/* Our attempts to extend MEM in place failed, just
+	   allocate-and-copy.  */
+	{
+	  void *new_mem = malloc (new_size - MALLOC_HEADER_SIZE);
+	  if (new_mem)
 	    {
-	      void *new_mem = malloc (new_size - MALLOC_HEADER_SIZE);
-	      if (new_mem)
-		{
-		  memcpy (new_mem, mem, size - MALLOC_HEADER_SIZE);
-		  free (mem);
-		}
-	      mem = new_mem;
+	      memcpy (new_mem, mem, size - MALLOC_HEADER_SIZE);
+	      free (mem);
 	    }
+	  mem = new_mem;
 	}
-      else if (new_size + MALLOC_REALLOC_MIN_FREE_SIZE <= size)
-	/* Shrink the block.  */
-	{
-	  __malloc_lock ();
-	  __heap_free (&__malloc_heap, base_mem + new_size, size - new_size);
-	  __malloc_unlock ();
-	  MALLOC_SET_SIZE (mem, new_size);
-	}
+    }
+  else if (new_size + MALLOC_REALLOC_MIN_FREE_SIZE <= size)
+    /* Shrink the block.  */
+    {
+      __malloc_lock ();
+      __heap_free (&__malloc_heap, base_mem + new_size, size - new_size);
+      __malloc_unlock ();
+      MALLOC_SET_SIZE (mem, new_size);
+    }
 
-      if (mem)
-	MALLOC_DEBUG ("  realloc: returning 0x%lx"
-		      " (base:0x%lx, total_size:%d)\n",
-		      (long)mem, (long)MALLOC_BASE(mem), (long)MALLOC_SIZE(mem));
+  if (mem)
+    MALLOC_DEBUG ("  realloc: returning 0x%lx"
+		  " (base:0x%lx, total_size:%d)\n",
+		  (long)mem, (long)MALLOC_BASE(mem), (long)MALLOC_SIZE(mem));
 
-      return mem;
-    }
+  return mem;
 }