Add xmalloc(), xcalloc() functions.

[pintos-anon] / src / threads / malloc.c

diff --git a/src/threads/malloc.c b/src/threads/malloc.c
index 487e93875ef4124ac314a7355429d4c2a632d1ab..9c83e3d438f780199166c3c92aa0893aa842f98f 100644 (file)
--- a/src/threads/malloc.c
+++ b/src/threads/malloc.c
@@ -153,6 +153,19 @@ malloc (size_t size)
   return b;
 }
 
+/* Obtains and returns a new block of at least SIZE bytes.
+   Panics if memory is not available.  It is unacceptable for the
+   kernel to panic in normal operation, so this function should
+   only be used during kernel initialization. */
+void *
+xmalloc (size_t size) 
+{
+  void *p = malloc (size);
+  if (p == NULL && size > 0)
+    PANIC ("memory exhausted");
+  return p;
+}
+
 /* Allocates and return A times B bytes initialized to zeroes.
    Returns a null pointer if memory is not available. */
 void *
@@ -161,7 +174,7 @@ calloc (size_t a, size_t b)
   void *p;
   size_t size;
 
-  /* Calculate block size. */
+  /* Calculate block size and make sure it fits in size_t. */
   size = a * b;
   if (size < a || size < b)
     return NULL;
@@ -174,6 +187,19 @@ calloc (size_t a, size_t b)
   return p;
 }
 
+/* Allocates and return A times B bytes initialized to zeroes.
+   Panics if memory is not available.  It is unacceptable for the
+   kernel to panic in normal operation, so this function should
+   only be used during kernel initialization. */
+void *
+xcalloc (size_t a, size_t b) 
+{
+  void *p = calloc (a, b);
+  if (p == NULL && a > 0 && b > 0)
+    PANIC ("memory exhausted");
+  return p;
+}
+
 /* Frees block P, which must have been previously allocated with
    malloc() or calloc(). */
 void
@@ -198,7 +224,7 @@ free (void *p)
     }
 
 #ifndef NDEBUG
-  memset (b, 0xcd, d->block_size);
+  memset (b, 0xcc, d->block_size);
 #endif
   
   lock_acquire (&d->lock);
@@ -228,8 +254,16 @@ static struct arena *
 block_to_arena (struct block *b)
 {
   struct arena *a = pg_round_down (b);
+
+  /* Check that the arena is valid. */
   ASSERT (a != NULL);
   ASSERT (a->magic == ARENA_MAGIC);
+
+  /* Check that the block is properly aligned for the arena. */
+  ASSERT (a->desc == NULL
+          || (pg_ofs (b) - sizeof *a) % a->desc->block_size == 0);
+  ASSERT (a->desc != NULL || pg_ofs (b) == sizeof *a);
+
   return a;
 }