# HG changeset patch
# User Bruno Haible <bruno@clisp.org>
# Date 1199098477 -3600
# Node ID 7913bdfb0cf852671906b96949e5c5e000488b15
# Parent  c487592d112a06734bb8f83fd254e07c927a1752
New macro xnmalloca.

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-12-30  Bruno Haible  <bruno@clisp.org>
+
+	* lib/xmalloca.h: Include xalloc.h.
+	(xnmalloca): New macro.
+
 2007-12-30  Bruno Haible  <bruno@clisp.org>
 
 	* lib/malloca.h (nmalloca): New macro.
diff --git a/lib/xmalloca.h b/lib/xmalloca.h
--- a/lib/xmalloca.h
+++ b/lib/xmalloca.h
@@ -19,6 +19,7 @@
 #define _XMALLOCA_H
 
 #include "malloca.h"
+#include "xalloc.h"
 
 
 #ifdef __cplusplus
@@ -40,9 +41,19 @@
   xmalloc (N)
 #endif
 
-/* Maybe we should also define a variant
-    xnmalloca (size_t n, size_t s) - behaves like xmalloca (n * s)
-   If this would be useful in your application. please speak up.  */
+/* xnmalloca(N,S) is an overflow-safe variant of xmalloca (N * S).
+   It allocates an array of N objects, each with S bytes of memory,
+   on the stack.  S must be positive and N must be nonnegative.
+   The array must be freed using freea() before the function returns.
+   Upon failure, it exits with an error message.  */
+#if HAVE_ALLOCA
+/* Rely on xmalloca (SIZE_MAX) calling xalloc_die ().  */
+# define xnmalloca(n, s) \
+    xmalloca (xalloc_oversized ((n), (s)) ? (size_t) (-1) : (n) * (s))
+#else
+# define xnmalloca(n, s) \
+    xnmalloc ((n), (s))
+#endif
 
 
 #ifdef __cplusplus