X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fxsize.h;h=2b955b635fa76cbb2466cd9573c24181179cdb33;hb=32d1664e8e930d8fa6a29db4caac4d21623e42c8;hp=4410193e663eaf3c65fc6a53a494d2fbb0160aa1;hpb=bf5c2a54b1f62943eec85b3baed47bc084cd36c2;p=gnulib.git

diff --git a/lib/xsize.h b/lib/xsize.h
index 4410193e6..2b955b635 100644
--- a/lib/xsize.h
+++ b/lib/xsize.h
@@ -1,6 +1,6 @@
 /* xsize.h -- Checked size_t computations.
 
-   Copyright (C) 2003 Free Software Foundation, Inc.
+   Copyright (C) 2003, 2008, 2009, 2010 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -14,7 +14,7 @@
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
 #ifndef _XSIZE_H
 #define _XSIZE_H
@@ -23,12 +23,10 @@
 #include <stddef.h>
 
 /* Get SIZE_MAX.  */
+#include <limits.h>
 #if HAVE_STDINT_H
 # include <stdint.h>
 #endif
-#ifndef SIZE_MAX
-# define SIZE_MAX ((size_t) -1)
-#endif
 
 /* The size of memory objects is often computed through expressions of
    type size_t. Example:
@@ -39,11 +37,11 @@
    To avoid this, the functions and macros in this file check for overflow.
    The convention is that SIZE_MAX represents overflow.
    malloc (SIZE_MAX) is not guaranteed to fail -- think of a malloc
-   implementation that uses mmap --, it's recommended to use SIZE_OVERFLOW_P
-   before invoking malloc().
+   implementation that uses mmap --, it's recommended to use size_overflow_p()
+   or size_in_bounds_p() before invoking malloc().
    The example thus becomes:
       size_t size = xsum (header_size, xtimes (n, element_size));
-      void *p = (!SIZE_OVERFLOW_P (size) ? malloc (size) : NULL);
+      void *p = (size_in_bounds_p (size) ? malloc (size) : NULL);
 */
 
 /* Convert an arbitrary value >= 0 to type size_t.  */
@@ -52,6 +50,9 @@
 
 /* Sum of two sizes, with overflow check.  */
 static inline size_t
+#if __GNUC__ >= 3
+__attribute__ ((__pure__))
+#endif
 xsum (size_t size1, size_t size2)
 {
   size_t sum = size1 + size2;
@@ -60,6 +61,9 @@ xsum (size_t size1, size_t size2)
 
 /* Sum of three sizes, with overflow check.  */
 static inline size_t
+#if __GNUC__ >= 3
+__attribute__ ((__pure__))
+#endif
 xsum3 (size_t size1, size_t size2, size_t size3)
 {
   return xsum (xsum (size1, size2), size3);
@@ -67,15 +71,30 @@ xsum3 (size_t size1, size_t size2, size_t size3)
 
 /* Sum of four sizes, with overflow check.  */
 static inline size_t
+#if __GNUC__ >= 3
+__attribute__ ((__pure__))
+#endif
 xsum4 (size_t size1, size_t size2, size_t size3, size_t size4)
 {
   return xsum (xsum (xsum (size1, size2), size3), size4);
 }
 
+/* Maximum of two sizes, with overflow check.  */
+static inline size_t
+#if __GNUC__ >= 3
+__attribute__ ((__pure__))
+#endif
+xmax (size_t size1, size_t size2)
+{
+  /* No explicit check is needed here, because for any n:
+     max (SIZE_MAX, n) == SIZE_MAX and max (n, SIZE_MAX) == SIZE_MAX.  */
+  return (size1 >= size2 ? size1 : size2);
+}
+
 /* Multiplication of a count with an element size, with overflow check.
    The count must be >= 0 and the element size must be > 0.
    This is a macro, not an inline function, so that it works correctly even
-   when N is of a wider tupe and N > SIZE_MAX.  */
+   when N is of a wider type and N > SIZE_MAX.  */
 #define xtimes(N, ELSIZE) \
   ((N) <= SIZE_MAX / (ELSIZE) ? (size_t) (N) * (ELSIZE) : SIZE_MAX)