On 07/04/2012 04:14 AM, Peter Krempa wrote:
@@ -460,6 +460,9 @@ _vshCalloc(vshControl *ctl, size_t nmemb, size_t size, const char *filename, int { char *x;
+ if (!size) + return NULL;
NACK to this; vshCalloc is defined as always returning non-NULL if it returns (even if it is a dummy malloc(0), assuming glibc semantics where you get a 1-byte allocation after all).
But assuming that 0 elements of something will never overflow we could change the macro to:
from: # ifndef xalloc_oversized # define xalloc_oversized(n, s) \ ((size_t) (sizeof(ptrdiff_t) <= sizeof(size_t) ? -1 : -2) / (s) < (n)) # endif
to: (s?((size_t) (sizeof(ptrdiff_t) <= sizeof(size_t) ? -1 : -2) / (s) < (n)):0)
NACK to this; this macro was copied from gnulib, and any changes should be made in gnulib first. But you'll have a hard time changing gnulib, since...
I found the actual problem for this. I think that this macro is in order. S is the size of the array element, which doesn't make sense to be 0 and N is the count of elements. The floating point exception happened because the count and size arguments were interchanged in the problematic place.
This is the real problem. We were using the macro incorrectly, and it is not a bug in the macro itself.
I'll send the patch anyways, but I don't think now, that the macro requires fixing.
Agreed - leave the macro alone. -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org