Code review of the new buffer protocol.  Mostly add questions that should
be answered with the comments removed.

There are many places that require checks when doing arithmetic for memory
sizes when allocating memory.  Otherwise, overflow is possible with
a subsequent crash.

Fix SF #1777057 which was a result of not initializing the new BufferError
properly.  Had to update the test for exceptions for BufferError too.
diff --git a/Objects/abstract.c b/Objects/abstract.c
index a48d5dc..4e25061 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -471,6 +471,7 @@
 
         /* Otherwise a more elaborate scheme is needed */
         
+	/* XXX(nnorwitz): need to check for overflow! */
         indices = (Py_ssize_t *)PyMem_Malloc(sizeof(Py_ssize_t)*(view->ndim));
         if (indices == NULL) {
                 PyErr_NoMemory();
@@ -521,6 +522,7 @@
 
         /* Otherwise a more elaborate scheme is needed */
         
+	/* XXX(nnorwitz): need to check for overflow! */
         indices = (Py_ssize_t *)PyMem_Malloc(sizeof(Py_ssize_t)*(view->ndim));
         if (indices == NULL) {
                 PyErr_NoMemory();
@@ -594,6 +596,7 @@
 
         /* Otherwise a more elaborate copy scheme is needed */
         
+	/* XXX(nnorwitz): need to check for overflow! */
         indices = (Py_ssize_t *)PyMem_Malloc(sizeof(Py_ssize_t)*view_src.ndim);
         if (indices == NULL) {
                 PyErr_NoMemory();
@@ -606,6 +609,7 @@
         }        
         elements = 1;
         for (k=0; k<view_src.ndim; k++) {
+		/* XXX(nnorwitz): can this overflow? */
                 elements *= view_src.shape[k];
         }
         while (elements--) {