reworked talloc() to in order to help track down invalid

memory access.

Tridge, I don't think using 0xdeadbeef for size allocations
of 0 is going to work.  I ended up having to use NULL
as much code that works on UNISTR checks to see if the buffer ptr
is NULL.  So valid code ends up with a seg fault.

Rather than rewriting it all, I added a DEBUG_TALLOC
#ifdef in talloc.h that sets a macro BAD_PTR.
This is the value assigned to ptr for an allocation of 0 bytes.



jerry
(This used to be commit 233b9cffa2350552d9f775f791d5d5e0464a1ed4)

2 files changed, 32 insertions, 25 deletions

diff --git a/source3/include/talloc.h b/source3/include/talloc.h
index a0dc3d9795..85a722d080 100644
--- a/source3/include/talloc.h
+++ b/source3/include/talloc.h
@@ -21,6 +21,12 @@
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
+#ifdef DEBUG_TALLOC
+#define BAD_PTR (void*)0xdeadbeef
+#else
+#define BAD_PTR NULL
+#endif
+
 struct talloc_chunk {
 	struct talloc_chunk *next;
 	void *ptr;
diff --git a/source3/lib/talloc.c b/source3/lib/talloc.c
index 577f761072..acc6204bed 100644
--- a/source3/lib/talloc.c
+++ b/source3/lib/talloc.c
@@ -55,37 +55,38 @@ TALLOC_CTX *talloc_init(void)
 void *talloc(TALLOC_CTX *t, size_t size)
 {
 	void *p;
-
 	if (size == 0)
 	{
 		/* debugging value used to track down
-		   memory problems */
-		p = (void*)0xdeadbeef;
+		   memory problems. BAD_PTR is defined
+		   in talloc.h */
+		p = BAD_PTR;
+		return p;
 	}
-	else
-	{
-		size = (size + (TALLOC_ALIGN-1)) & ~(TALLOC_ALIGN-1);
-
-		if (!t->list || (t->list->total_size - t->list->alloc_size) < size) {
-			struct talloc_chunk *c;
-			size_t asize = (size + (TALLOC_CHUNK_SIZE-1)) & ~(TALLOC_CHUNK_SIZE-1);
-
-			c = (struct talloc_chunk *)malloc(sizeof(*c));
-			if (!c) return NULL;
-			c->next = t->list;
-			c->ptr = (void *)malloc(asize);
-			if (!c->ptr) {
-				free(c);
-				return NULL;
-			}
-			c->alloc_size = 0;
-			c->total_size = asize;
-			t->list = c;
-		}
 
-		p = ((char *)t->list->ptr) + t->list->alloc_size;
-		t->list->alloc_size += size;
+	/* normal code path */
+	size = (size + (TALLOC_ALIGN-1)) & ~(TALLOC_ALIGN-1);
+
+	if (!t->list || (t->list->total_size - t->list->alloc_size) < size) {
+		struct talloc_chunk *c;
+		size_t asize = (size + (TALLOC_CHUNK_SIZE-1)) & ~(TALLOC_CHUNK_SIZE-1);
+
+		c = (struct talloc_chunk *)malloc(sizeof(*c));
+		if (!c) return NULL;
+		c->next = t->list;
+		c->ptr = (void *)malloc(asize);
+		if (!c->ptr) {
+			free(c);
+			return NULL;
+		}
+		c->alloc_size = 0;
+		c->total_size = asize;
+		t->list = c;
 	}
+
+	p = ((char *)t->list->ptr) + t->list->alloc_size;
+	t->list->alloc_size += size;
+
 	
 	return p;
 }