Revision: 41326
http://brlcad.svn.sourceforge.net/brlcad/?rev=41326&view=rev
Author: brlcad
Date: 2010-11-11 02:53:45 +0000 (Thu, 11 Nov 2010)
Log Message:
-----------
libbu memory management is not allowed to return NULL (by design) so having
bu_realloc() free memory then return NULL for the case where the size is zero
but the pointer is non-NULL would be inconsistent with that design.
FORTUNATELY, the standard allows for the return of 'a unique pointer that can
be successfully passed to free()' so go ahead and return a new uninitialized
minimum-sized allocation. this is consistent with c99 and IEEE Std 1003.1-2001.
Modified Paths:
--------------
brlcad/trunk/src/libbu/malloc.c
Modified: brlcad/trunk/src/libbu/malloc.c
===================================================================
--- brlcad/trunk/src/libbu/malloc.c 2010-11-11 02:33:58 UTC (rev 41325)
+++ brlcad/trunk/src/libbu/malloc.c 2010-11-11 02:53:45 UTC (rev 41326)
@@ -363,23 +363,26 @@
/* If bu_realloc receives a NULL pointer and zero size then bomb
* because the behavior of realloc is undefined for these inputs.
*/
- if (UNLIKELY(!siz && !ptr)) {
+ if (UNLIKELY(ptr == NULL && siz == 0)) {
bu_bomb("bu_realloc(): invalid input, NULL pointer and zero size\n");
}
/* If bu_realloc receives a NULL pointer and non-zero size then
- * allocate the memory.
+ * allocate new memory.
*/
- if (UNLIKELY(!ptr)) {
+ if (UNLIKELY(ptr == NULL && siz > 0)) {
return bu_malloc(siz, str);
}
/* If bu_realloc receives a non-NULL pointer and zero size then
- * free the memory.
+ * free the memory. Instead of returning NULL, though, the
+ * standard says we can return a small allocation suitable for
+ * passing to bu_free(). Do that so we can maintain are LIBBU
+ * guarantee of worry-free memory management.
*/
- if (UNLIKELY(!siz)) {
+ if (UNLIKELY(ptr != NULL && siz == 0)) {
bu_free(ptr, str);
- return (genptr_t)NULL;
+ return bu_malloc(MINSIZE, str);
}
/* If the new allocation size is smaller than the minimum size
@@ -411,8 +414,12 @@
"or not allocated with bu_malloc! Ignored.\n",
ptr, str);
/*
- * Since we're ignoring this, atleast return the pointer
- * that was passed in. We should probably return NULL.
+ * Since we're ignoring this, at least return the pointer
+ * that was passed in. Standard says behavior is
+ * undefined when reallocating memory not allocated with
+ * the matching allocation routines (i.e., bu_malloc() or
+ * bu_calloc() in our situation), so we are fair game to
+ * just return the pointer we were given.
*/
return ptr;
}
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