[PATCHv2 2/2] mkfs.jffs2: fix casting of __off64_t

[Andy Shevchenko]

On Mon, 2011-04-18 at 17:07 +0300, ext Artem Bityutskiy wrote:
> On Mon, 2011-04-18 at 10:04 -0400, Mike Frysinger wrote:
> > On Mon, Apr 18, 2011 at 09:55, Artem Bityutskiy wrote:
> > > On Mon, 2011-04-18 at 09:49 -0400, Mike Frysinger wrote:
> > >> On Mon, Apr 18, 2011 at 04:31, Andy Shevchenko wrote:
> > >> > The casting of __off64_t to unsigned long potentially wrong for values higher
> > >> > than ULONG_MAX.  Let's fix that.
> > >>
> > >> i dont think this is the way to go.  on 64bit systems, long long is
> > >> 128bits.  i imagine the way to go (assuming we're always using LFS) is
> > >> to use PRIu64 from inttypes.h
> > >
> > > sizeof(unsigned long long) is 8 (64 bits) on my x86_64 fedora.
> > 
> > so it is.  i still think PRIu64 is the correct way to handle this as
> > there is no sizeof() assumption and no need for casting.
> 
> Never used this, but yes, as long as this is something which has worked
> for ages and we are not going to have "this is not supported" issues -
> sure!
This is described in C99 ISO standard [1].

> But unsigned long long is 64 bits I think in all GNU systems, and
> casting to unsigned long long is quite standard practice AFAIK, so I do
> not see why it would be very bad thing to do.
Yeah, some projects use following approach
#ifndef PRIu64
#define PRIu64 "llu"
#endif

The opposite recommendation is to put "%9jd" classifier to print st_size field of struct stat [2].

[1]
http://pubs.opengroup.org/onlinepubs/000095399/basedefs/inttypes.h.html
[2] http://pubs.opengroup.org/onlinepubs/009695399/functions/printf.html


-- 
With Best Regards,
Andy Shevchenko