Re: [Qemu-devel] [PATCH v6 2/6] qapi: Introduce add-fd, remove-fd, query-fdsets

[Stefan Hajnoczi]

On Tue, Aug 7, 2012 at 8:59 PM, Corey Bryant <address@hidden> wrote:
>
>
> On 08/07/2012 02:16 PM, Stefan Hajnoczi wrote:
>>
>> On Fri, Aug 3, 2012 at 6:28 PM, Corey Bryant <address@hidden>
>> wrote:
>>> +    snprintf(fd_str, sizeof(fd_str), "%ld", fd);
>>> +    qerror_report(QERR_FD_NOT_FOUND, fd_str);
>>
>>
>> Why use an fd_str instead of passing an int64_t into the error
>> message?  This also assumed sizeof(long) == 8, which isn't true on
>> 32-bit hosts, so %ld should be %"PRId64".
>
>
> Can I pass an int64_t into the message if it takes a string?
>
> I thought int64_t was a long long in 32-bit mode, but perhaps that's not
> always the case?

The PRId64 format specifier macro from the C standard hides this so
you can pass int64_t values to printf()-style functions in a portable
way.

Stefan