--- ray/src/common/malloc.c	1990/10/03 21:01:59	1.9
+++ ray/src/common/malloc.c	1991/04/02 09:36:21	1.12
@@ -1,4 +1,4 @@
-/* Copyright (c) 1990 Regents of the University of California */
+/* Copyright (c) 1991 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -23,7 +23,6 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #ifdef MSTATS
 #include  <stdio.h>
-
 static unsigned	b_nalloced = 0;
 static unsigned	b_nfreed = 0;
 static unsigned	b_nscrounged = 0;
@@ -42,21 +41,30 @@ static unsigned	m_nwasted = 0;
 #define  MAXINCR	(1<<16)			/* largest sbrk(2) increment */
 
 #ifdef  NOVMEM
-#define  getpagesize()	BYTES_WORD
+#define  getpagesize()	1024
 #endif
 					/* malloc free lists */
 typedef union m_head {
 	union m_head	*next;
-	int		bucket;
+	struct {
+		short		magic;
+		short		bucket;
+	}	a;
 	ALIGN		dummy;
 } M_HEAD;
 
+#define MAGIC		0x1a2		/* magic number for allocated memory */
+
 #define FIRSTBUCKET	3
 #define NBUCKETS	30
 
 static M_HEAD	*free_list[NBUCKETS];
 
+static ALIGN	dummy_mem;
 
+#define DUMMYLOC	((char *)&dummy_mem)
+
+
 char *
 mscrounge(np)		/* search free lists to satisfy request */
 register unsigned	*np;
@@ -171,6 +179,9 @@ unsigned	n;
 	register M_HEAD	*mp;
 	register int	bucket;
 	register unsigned	bsiz;
+					/* don't return NULL on 0 request */
+	if (n == 0)
+		return(DUMMYLOC);
 					/* find first bucket that fits */
 	for (bucket = FIRSTBUCKET, bsiz = 1<<FIRSTBUCKET;
 			bucket < NBUCKETS; bucket++, bsiz <<= 1)
@@ -192,7 +203,8 @@ unsigned	n;
 		mp = free_list[bucket];
 		free_list[bucket] = mp->next;
 	}
-	mp->bucket = bucket;			/* tag block */
+	mp->a.magic = MAGIC;			/* tag block */
+	mp->a.bucket = bucket;
 	return((char *)(mp+1));
 }
 
@@ -205,8 +217,8 @@ unsigned	n;
 	char	*p;
 	register unsigned	on;
 					/* get old size */
-	if (op != NULL)
-		on = 1 << ((M_HEAD *)op-1)->bucket;
+	if (op != NULL && op != DUMMYLOC && ((M_HEAD *)op-1)->a.magic == MAGIC)
+		on = 1 << ((M_HEAD *)op-1)->a.bucket;
 	else
 		on = 0;
 	if (n <= on && (n > on>>1 || on == 1<<FIRSTBUCKET))
@@ -229,10 +241,12 @@ char	*p;
 	register M_HEAD	*mp;
 	register int	bucket;
 
-	if (p == NULL)
+	if (p == NULL || p == DUMMYLOC)
 		return;
 	mp = (M_HEAD *)p - 1;
-	bucket = mp->bucket;
+	if (mp->a.magic != MAGIC)		/* sanity check */
+		return;
+	bucket = mp->a.bucket;
 	mp->next = free_list[bucket];
 	free_list[bucket] = mp;
 #ifdef MSTATS