Re: recvmsg/sendmsg broken on mips64

[Sebastian Gottschall <s.gottschall@dd-wrt.com>]

Am 01.04.2016 um 11:49 schrieb Szabolcs Nagy:
> * Sebastian Gottschall <s.gottschall@dd-wrt.com> [2016-04-01 11:16:20 +0200]:
>> I discovered that the whole recvmsg/sendmsg code is broken in mips64
>> but i found also the solution
>> i throwed out all the _pad1, _pad2 crap in socket.h and the corrosponding
>> code in recvmsg.c etc.
>> and used size_t instead. this works at the end. i see no reason for this
>> padding, since using the correct datatype will handle it in the same way.
>> this solution may also work for other 64 bit targets. so proposal is fixing
>> the datatype instead of using int with padding in case of 64 bit
>>
> the padding is needed, i think __BIG_ENDIAN
> or __LITTLE_ENDIAN might not be defined properly.
i checked this already. it was defined properly. the only solution was 
using the correct datatypes as defined in the kernel and i also checked 
uclibc. it uses also just size_t and nothing else.
the padding results in the same datatype size, just clears the upper and 
lower word. but this doesnt seem to be neccessary
> your fix is non-conforming and breaks both abi and api,
> the definition must match
socklen_t would result in the same 64bit datatype instead of int + pad 
(which is 64 bit too). so its conforming.
i mached by header variant by reading the kernel headers which uses 
size_t instead of socketlen_t
so i assume socketlen_t maches size_t
>
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html
>
>> this here is my working struct in mips64 (big endian)
>>
>> struct msghdr {
>>          void *msg_name;
>>          socklen_t msg_namelen;
>>          struct iovec *msg_iov;
>>          size_t msg_iovlen;
>>          void *msg_control;
>>          size_t msg_controllen;
>>          int msg_flags;
>> };
>>
>> struct cmsghdr {
>>          size_t cmsg_len;
>>          int cmsg_level;
>>          int cmsg_type;
>> };
>>
>>
>> Sebastian