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

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

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?

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

-- 
MST