lua-socket vs sockaddr_un

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

When building net/lua-socket, defining UNIX_HAS_SUN_LEN alters the size 
passed to socket_bind() to take into account the difference in definitions 
of sockaddr_un on Linux vs other OSes:

https://github.com/lunarmodules/luasocket/blob/4844a48fbf76b0400fd7b7e4d15d244484019df1/src/unixstream.c#L191-L199

If the platform (PLAT) is set to macos or freebsd, UNIX_HAS_SUN_LEN is 
defined:
https://github.com/lunarmodules/luasocket/blob/4844a48fbf76b0400fd7b7e4d15d244484019df1/src/makefile#L190-L201

However, pkgsrc does not set the platform and so it defaults to linux, 
meaning UNIX_HAS_SUN_LEN is not defined and therefore the filename of the 
socket gets truncated. As pkgsrc is cross-platform, it's probably OK to 
carry on with PLAT=linux, but set UNIX_HAS_SUN_LEN based on PLATFORM in 
the Makefile.

On the other hand, this also just looks like over-engineering in 
luasocket to me. What's wrong with just using sizeof(sockaddr_un) 
unconditionally? Even taking the BUGS section of the relevant Linux man 
page into account, the length check and memcpy() calls should be OK.

https://man7.org/linux/man-pages/man7/unix.7.html#BUGS

--
Stephen