Re: [Bug-gnulib] addition: xsize.h

[Bruno Haible]

While applying xsize.h to vasnprintf.c and printf-parse.c, I found a
maximum function comfortable. I thus did this change.

2003-11-16  Bruno Haible  <address@hidden>

        * xsize.h (xmax): New function.
        (xsum, xsum3, xsum4): Declare as "pure" functions.

diff -r -c3 --exclude='*.po*' --exclude='*.info*' --exclude='*.html' 
--exclude=Makefile.in --exclude=aclocal.m4 --exclude=configure 
--exclude=po-gram-gen.c --exclude=po-gram-gen.h --exclude=po-hash-gen.c 
--exclude=po-hash-gen.h --exclude='*.o' --exclude='*.lo' 
gettext-5/gettext-tools/lib/xsize.h gettext-6/gettext-tools/lib/xsize.h
*** gettext-5/gettext-tools/lib/xsize.h Tue Nov 11 12:43:59 2003
--- gettext-6/gettext-tools/lib/xsize.h Mon Nov 17 00:33:20 2003
***************
*** 37,47 ****
     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().
     The example thus becomes:
        size_t size = xsum (header_size, xtimes (n, element_size));
!       void *p = (!SIZE_OVERFLOW_P (size) ? malloc (size) : NULL);
  */
  
  /* Convert an arbitrary value >= 0 to type size_t.  */
--- 37,47 ----
     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()
!    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_in_bounds_p (size) ? malloc (size) : NULL);
  */
  
  /* Convert an arbitrary value >= 0 to type size_t.  */
***************
*** 50,55 ****
--- 50,58 ----
  
  /* 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;
***************
*** 58,63 ****
--- 61,69 ----
  
  /* 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);
***************
*** 65,75 ****
--- 71,96 ----
  
  /* 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