id	summary	reporter	owner	description	type	status	milestone	component	resolution	keywords	cc
19	Doesn't work on 64 bit machines with 32 bit userspace	Sjoerd Simons <sjoerd@…>	lennart	"Hi,

  sendmsg on 64 bit machines with 32 bit userspace always throws -EINVAL with current avahi. 
This is because the code does the following: 
  size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1]; to allocate 
  the cmsg data and then passed the size of that as msg.msg_controllen. 

Which makes it always somewhat too large, CMSG_SPACE returns a value with padding for allignment if needed, which normally is a multiple of sizeof(size_t). So it's always sizeof(size_t) too large..

Now normally this isn't too big a problem. Unfortunately the 32to64 bit translation code in the linux kernel assumes that if after a cmsg there is still some data left it's another valid cmsg.. 
Which isn't in this case so it throws EINVAL.

Two possible solution, either pass the CMS_SPACE as msg.msg_controllen or don't allocate too much space on the heap. I'll attach a patch that uses the second solution."	defect	closed	Avahi 0.6.10	avahi-core	fixed		sebastien.estienne@…