Re: [Qemu-devel] Re: [PATCH] win32: use PRId64 instead of %lld

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jan 25, 2010 at 09:32:05PM +0200, Michael S. Tsirkin wrote:
> On Mon, Jan 25, 2010 at 08:23:22PM +0100, Stefan Weil wrote:
> > Michael S. Tsirkin schrieb:
> > > On Mon, Jan 25, 2010 at 06:32:06PM +0100, Stefan Weil wrote:
> > >> Michael S. Tsirkin schrieb:
> > >>> On Sun, Jan 24, 2010 at 09:23:41PM +0000, Herve Poussineau wrote:
> > >>>> Replace %lld occurrences by PRId64.
> > >>> This is wrong.
> > >>> long long values should be printed with %lld.
> > >>> size_t - with %zd. PRId64 is for int64_t.
> > >>>
> > >> size_t => %zu, ssize_t => %zd might be better.
> > >>
> > >> And none of them works on win32, so using them
> > >> there can result in a crash:
> > >>
> > >> size_t st = 4711;
> > >> fprintf(stderr, "st=%zu, %s\n", st, "test");
> > >>
> > >> printf functions on win32 don't know %z.
> > >> They run
> > >>
> > >> fprintf(stderr, "st=zu, %s\n", st, "test");
> > >>
> > >> which results in an memory access fault when printf
> > >> wants to read the memory at address 0x4711.
> > >>
> > >> Regards,
> > >> Stefan Weil
> > >
> > > Let's just implement a compliant printf?
> > 
> > Or format the harddisk and install linux?
> > Maybe that would be the better option :-)
> > 
> > Of course you can add a printf to qemu, or to mingw32.
> > No need to implement it - there are lots of good free
> > implementations.
> > 
> > The mingw developers are aware of the problem
> > (http://www.mail-archive.com/mingw-w64-public@lists.sourceforge.net/msg00416.html).
> > 
> > If there is an easy solution, they will fix the problem.
> > 
> > I don't think the problem can be fixed easy:
> > there is not only printf but a lot of functions which use
> > format strings. They are implemented in msvcrt.dll.
> > Replacing single functions in a dll is difficult.
> > Telling code which printf in which dll is the correct
> > one is difficult, too.
> > 
> > There are easy solutions for QEMU: type cast
> > size_t values to unsigned or uint32_t in printf
> > or use a new macro (for example PRIsize) in
> > format strings. That macro would be different for
> > mingw32 and standard conforming systems.
> 
> 
> The link above suggests adding
> -D__USE_MINGW_ANSI_STDIO=1
> why don't we do just do this with mingw?

Looking a bit lower, maybe just -std=c99.

> People should also build with -Werror, then
> it would be a build error not a crash.
> 
> -- 
> MST