New macro xnmalloca.

diff --git a/ChangeLog b/ChangeLog
index 32c0264..207323a 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 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.
        * lib/c-strcasestr.c (knuth_morris_pratt): Use it.
        * lib/c-strstr.c (knuth_morris_pratt): Likewise.

diff --git a/lib/xmalloca.h b/lib/xmalloca.h
index 4a96300..bd4c5a9 100644 (file)
--- 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 @@ extern void * xmmalloca (size_t n);
   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