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

[Stefan Weil <weil@mail.berlios.de>]

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.