[libvirt] build failure on 32-bit

[Eric Blake]

On 07/13/2016 03:14 AM, Daniel P. Berrange wrote:
> On Tue, Jul 12, 2016 at 11:48:11AM -0600, Eric Blake wrote:
>> I hit an interesting failure on my 32-bit F24 machine:
>>
>> In file included from ../../src/util/virconf.c:32:0:
>> ../../src/util/virconf.c: In function 'virConfGetValueSSizeT':
>> ../../src/util/virconf.c:1269:26: error: format '%zd' expects argument
>> of type 'signed size_t', but argument 9 has type 'long int'
>> [-Werror=format=]
>>                         _("%s: value for '%s' parameter must be in range
>> %zd:%zd"),
>>
>> In context, it is because we are using SSIZE_MAX as the argument paired
>> to %zd.
>>
>> Technically, the standards documents do NOT require ssize_t to have any
>> relation to size_t, and thus there is NO portable way to pass ssize_t
>> values to printf() without a cast; but in practice, most systems are
>> sane enough that 'ssize_t' is the same type as 'signed size_t', as
>> requested by gcc.  This includes 32-bit glibc (where size_t is unsigned
>> int, and ssize_t is int).
>>
>> But it turns out it is a glibc bug:
>> https://sourceware.org/bugzilla/show_bug.cgi?id=13575 - SSIZE_MAX must
>> have type ssize_t, and glibc is at fault for defining it as a 'long'
>> value even when ssize_t is an 'int'.
>>
>> Once gnulib works around it, I'll update libvirt's gnulib submodule to
>> fix the libvirt build on 32-bit Linux again.
> 
> Should we just add a cast temporarily ?
> 

Doesn't scale as nicely, but yes, that's a reasonable temporary workaround.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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