[libvirt] [PATCH 2/2] virNetServerClientNewPostExecRestart: Avoid align problems

Michal Privoznik mprivozn at redhat.com
Thu May 5 10:26:37 UTC 2016

On 05.05.2016 11:05, Erik Skultety wrote:
> On 05/05/16 09:30, Michal Privoznik wrote:
>> I've noticed this while trying to compile libvirt on my arm box.
>>   CC       rpc/libvirt_net_rpc_server_la-virnetserverclient.lo
>> rpc/virnetserverclient.c: In function 'virNetServerClientNewPostExecRestart':
>> rpc/virnetserverclient.c:516:45: error: cast increases required alignment of target type [-Werror=cast-align]
>>                                              (long long *) &timestamp) < 0) {
>>                                              ^
>> cc1: all warnings being treated as errors
>> Problem is, @timestap is defined as time_t which is 32 bits long,
>> and we are typecasting it to long long which is 64bits long.
>> Solution is to make @timestamp type of long long. But that could
>> overflow when passing the variable to
>> virNetServerClientNewInternal(). Well, we can do this and hope to
>> find a better solution for this till 19 January 2038 (yes, time_t
>> on my arm box is signed long int).
> Hmm, why don't we then represent the timestamp as long long in the first
> place, rather than having it as time_t. That way, no overflow as you
> mention could happen and the only problem for your machine then would be
> to cope with the 32bit timestamp time function returns, which will break
> libvirt and anything else anyway, but at least in an expected manner.

I don't know. It's not me who wrote the code :-P But sure, we could do
that. It's going to be just a broadening of my patch anyway.


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