Re: [PATCH 3/7] linux: Use the expected size for SO_TIMESTAMP{NS} convertion

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 05/07/2021 16:00, Florian Weimer wrote:
> * Adhemerval Zanella via Libc-alpha:
> 
>> Kernel returns 32-bit values for COMPAT_SO_TIMESTAMP{NS}_OLD,
>> no 64-bit ones.
> 
> “not 64-bit values”?

Ack.

> 
>> diff --git a/sysdeps/unix/sysv/linux/convert_scm_timestamps.c b/sysdeps/unix/sysv/linux/convert_scm_timestamps.c
>> index 5af71847f5..2db5750f50 100644
>> --- a/sysdeps/unix/sysv/linux/convert_scm_timestamps.c
>> +++ b/sysdeps/unix/sysv/linux/convert_scm_timestamps.c
>> @@ -44,7 +44,8 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
>>       'struct __kernel_sock_timeval' while for SO_TIMESTAMPNS_NEW is a
>>       'struct __kernel_timespec'.  In either case it is two uint64_t
>>       members.  */
>> -  uint64_t tvts[2];
>> +  int64_t tvts[2];
>> +  int32_t tmp;
>>  
>>    struct cmsghdr *cmsg, *last = NULL;
>>    int type = 0;
>> @@ -69,7 +70,10 @@ __convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
>>  
>>  	/* fallthrough  */
>>  	common:
>> -	  memcpy (tvts, CMSG_DATA (cmsg), sizeof (tvts));
>> +	  memcpy (&tmp, CMSG_DATA (cmsg), sizeof (tmp));
>> +	  tvts[0] = tmp;
>> +	  memcpy (&tmp, CMSG_DATA (cmsg) + sizeof (tmp), sizeof (tmp));
>> +	  tvts[1] = tmp;
>>  	  break;
> 
> Maybe it's clearer to make tmp an array and use a single memcpy call?

I agreed, I change it to your suggestion.