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

[Stefan Weil]

Stefan Weil schrieb:
> 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
>
>

Hi,

I just read this which could explain crashes with %lld:

/* MSVCRT supports additional length specifiers for "printf". (In
fact, it does not support some of the C99 specifiers, like
"ll". However, we do not presently have a mechanism for disabling
a specifier.) */

A short test:
    long long ll = 0;
    printf("ll=%lld, string=%s\n", ll, "test");

ll=0, string=(null)

=> You can crash QEMU for win32 with %lld.

Regards,
Stefan