On Sat, Jun 26, 2010 at 05:11:39AM +0200, Alistair Crooks wrote: > On Sat, Jun 26, 2010 at 01:32:05AM +0200, Joerg Sonnenberger wrote: > > On Fri, Jun 25, 2010 at 11:54:32PM +0200, Alistair Crooks wrote: > > > Even in C99, the "%lu" method will work unless size_t is bigger than > > > unsigned long *and* the value being printed exceeds ULONG_MAX, which > > > is unlikely to happen in practice. > > Please get the attributions right - I was quoting that text. > > > Actually, it doesn't. This method breaks as soon as size_t != u_long and > > might only work in a few edge cases like the size_t being the last > > argument and the byte order is Little Endian. This is worse because IIRC > > Microsoft decided to use IL32LLP64 or something similarly fancy. > > Can you give us a reference to this, please?
E.g. http://stackoverflow.com/questions/384502/what-is-the-bit-size-of-long-on-64-bit-windows and the MSDN reference inside. > > A more portable approach with autoconf can be found in pkg_install, look > > for MISSING_SIZE_T_SUPPORT and the corresponding AC_CHECK_SIZEOF calls > > in configure.ac. > > Hmmm, I see this in configure.ac - > > AC_CHECK_SIZEOF(int) > AC_CHECK_SIZEOF(long) > AC_CHECK_SIZEOF(long long) > AC_CHECK_SIZEOF(size_t, [#include <stdlib.h>]) ...compute the sizes to not depend on SIZE_MAX (which would simplify the logic a lot). > and > > case $host in > *-*-hpux*) > AC_DEFINE(MISSING_SIZE_T_SUPPORT) > AH_TEMPLATE([MISSING_SIZE_T_SUPPORT], [ > Define to 1 if the `z' modifider for printf is missing. > ]) > ;; > esac The only platform for pkgsrc purposes ATM which lacks the %z support. > and > > #ifndef MISSING_SIZE_T_SUPPORT > # define PRIzu "zu" > #elif SIZEOF_SIZE_T == SIZEOF_INT > # define PRIzu "u" > #elif SIZEOF_SIZE_T == SIZEOF_LONG > # define PRIzu "lu" > #elif SIZEOF_SIZE_T == SIZEOF_LONG_LONG > # define PRIzu "llu" > #else > # errror "Unknown size_t size" > #endif > > Not quite what I'd been expecting, though, from the glowing description > above. It would be simpler if SIZE_MAX support can be assumed. In that case it would boil down to #if SIZE_MAX == INT_MAX #define PRIzu "u" #elif SIZE_MAX == LONG_MAX #define PRIzu "lu" #else SIZE_MAX == LLONG_MAX #define PRIzu "llu" #endif Joerg
