On Sat, 26 Apr 2014 12:07:06 +0800 Wang Nan <wangnan0 at huawei.com> wrote: > From: Wang Nan <pi3orama at gmail.com> > > According to C standard, numerical limitations macros such as ULONG_MAX > should be defined in <limits.h>, and must be defined as "constant > expressions suitable for use in #if preprocessing directives." (see > "Numerical limits" section in the standard). > > Original definition in common.h breaks this rule: > > #define LONG_MAX ((long)(~0UL>>1)) > > which causes macros like following failure: > > #if LONG_MAX == 2147483647 > # define LONG_BIT 32 > #else > # define LONG_BIT 64 > #endif > > Unfortunately, the above code piece is taken from real glibc header > (/usr/include/bits/xopen_lim.h), which is happen to be included by > <limits.h> if _GNU_SOURCE is defined. > > This patch include <limits.h> in common.h to use C standard numerical > macros. For system without such macros defined by C, this patch also > defines L(L)ONG_MAX in a standard compatible way. By checking wich > > gcc -dM -E - <<<'' > > we know that __LONG_MAX__ and __LLONG_MAX__ macros should be defined by > gcc by default. Definition of ULONG_MAX and ULLONG_MAX are taken from > gcc standard include file (include-fixed/limits.h). > > In addition, macro ULONGLONG_MAX is nonstandard, the standard way for > defining max ulonglong is ULLONG_MAX. > > Signed-off-by: Wang Nan <wangnan0 at huawei.com> > Cc: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp> > Cc: Petr Tesarik <ptesarik at suse.cz> > Cc: kexec at lists.infradead.org > Cc: Geng Hui <hui.geng at huawei.com> > Cc: Liu Hua <sdu.liu at huawei.com> > > --- > common.h | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/common.h b/common.h > index 6ad3ca7..124f107 100644 > --- a/common.h > +++ b/common.h > @@ -16,17 +16,29 @@ > #ifndef _COMMON_H > #define _COMMON_H > > +#include <limits.h> > + > #define TRUE (1) > #define FALSE (0) > #define ERROR (-1) > > #ifndef LONG_MAX > -#define LONG_MAX ((long)(~0UL>>1)) > +# warning LONG_MAX should have been defined in <limits.h> > +# define LONG_MAX __LONG_MAX__ > #endif > #ifndef ULONG_MAX > -#define ULONG_MAX (~0UL) > +# warning ULONG_MAX should have been defined in <limits.h> > +# define ULONG_MAX (LONG_MAX * 2UL + 1UL) > +#endif > +#ifndef LLONG_MAX > +# warning LLONG_MAX should have been defined in <limits.h> > +# define LLONG_MAX __LONG_LONG_MAX__ > +#endif > +#ifndef ULLONG_MAX > +# warning ULLONG_MAX should have been defined in <limits.h> > +# define ULLONG_MAX (LLONG_MAX * 2ULL + 1ULL) > #endif > -#define ULONGLONG_MAX (~0ULL) > +#define ULONGLONG_MAX ULLONG_MAX Hi Wang Nan, is this actually needed on some known platform? If not, then I'd rather remove all these #ifndef stanzas and rely on <limits.h>. I mean, if you can't rely on standard C constants, then why should be the gcc-specific pre-defined macros (__LONG_MAX__ et al.) available? It's probably better to put the burden on the person doing the port, because they should know what is appropriate for their compiler and/or libc. Just my opinion, Petr T
