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authorDaniel P. Berrange <berrange@redhat.com>2013-09-09 09:59:45 +0100
committerDaniel P. Berrange <berrange@redhat.com>2013-09-09 16:42:01 +0100
commitde0c5b13f7f2058f90dfd6425b3d337f137759fd (patch)
tree79da992d68f6f61a60f9845e19064bfa0ddc626d
parent7b7d750f87a7111e2e405f5de578e6bbaed7e1a9 (diff)
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Import gnulib's xalloc_oversized macro
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
-rw-r--r--libvirt-override.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/libvirt-override.c b/libvirt-override.c
index 246a15b..acd06a6 100644
--- a/libvirt-override.c
+++ b/libvirt-override.c
@@ -20,6 +20,7 @@
#include <Python.h>
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>
+#include <stddef.h>
#include "typewrappers.h"
#include "build/libvirt.h"
@@ -35,6 +36,21 @@ extern void initcygvirtmod(void);
# define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif
+/* Return 1 if an array of N objects, each of size S, cannot exist due
+ to size arithmetic overflow. S must be positive and N must be
+ nonnegative. This is a macro, not a function, so that it
+ works correctly even when SIZE_MAX < N.
+
+ By gnulib convention, SIZE_MAX represents overflow in size
+ calculations, so the conservative dividend to use here is
+ SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
+ However, malloc (SIZE_MAX) fails on all known hosts where
+ sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
+ exactly-SIZE_MAX allocations on such hosts; this avoids a test and
+ branch when S is known to be 1. */
+#define xalloc_oversized(n, s) \
+ ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
+
#if 0
# define DEBUG_ERROR 1
#endif