Hello,
I have a small feature request for lib/xsize.h: a variadic function,
xsumn, to safely sum any number of size_t type arguments. Similar to
xsum3 and xsum4. Attached is a small patch.
Also, I'm curious if this file needs documentation? I could not find
any in doc/.
--
Mansour
From 9bcc0e94b891221b9537a8e9faac080ca6b78e95 Mon Sep 17 00:00:00 2001
From: Mansour Moufid <mansourmou...@gmail.com>
Date: Thu, 22 Sep 2011 12:05:42 -0400
Subject: [PATCH] Add a new `xsumn' function to `lib/xsize.h'.
This implements a variadic sum function with overflow checking,
similar to xsum{2,3,4} but for an arbitrary n number of arguments.
For example:
size_t size = xsumn (4, 9, 10, 11, 12);
/* size == 42 */
void *p = (size_in_bounds_p (size) ? malloc (size) : NULL);
---
lib/xsize.h | 20 ++++++++++++++++++++
1 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/lib/xsize.h b/lib/xsize.h
index f75655a..af2fd2d 100644
--- a/lib/xsize.h
+++ b/lib/xsize.h
@@ -28,6 +28,8 @@
# include <stdint.h>
#endif
+#include <stdarg.h>
+
/* The size of memory objects is often computed through expressions of
type size_t. Example:
void* p = malloc (header_size + n * element_size).
@@ -79,6 +81,24 @@ xsum4 (size_t size1, size_t size2, size_t size3, size_t size4)
return xsum (xsum (xsum (size1, size2), size3), size4);
}
+/* Sum of n sizes, with overflow check. */
+static inline size_t
+xsumn (size_t n, ...)
+{
+ va_list ap;
+ size_t i, x, sum = 0;
+
+ va_start (ap, n);
+ for (i = 0; i < n; i++)
+ {
+ x = va_arg (ap, size_t);
+ sum = xsum (sum, x);
+ }
+ va_end (ap);
+
+ return sum;
+}
+
/* Maximum of two sizes, with overflow check. */
static inline size_t
#if __GNUC__ >= 3
--
1.7.1
