On 02/29/2016 07:52 AM, Eli Zaretskii wrote:
> I was talking about systems other than Windows. Do we know which ones 
> of them still use the non-getaddrinfo code?

The Gnulib documentation mentions HP-UX 11.11, IRIX 6.5, OSF/1 5.1, 
Solaris 7, Cygwin 1.5.x, mingw, MSVC 9, Interix 3.5, BeOS. Of the 
non-MS-Windows ports, Emacs should run on HP-UX 11, Solaris 7, and 
(assuming --with-wide-int) IRIX 6.5. Of these only HP-UX 11.11 (aka 
HP-UX 11i) is still a viable platform. The base system lacks 
getaddrinfo, but there is an optional addon to support getaddrinfo (it's 
part of IPv6 support)

> I see that we have calls to something named res_init there, and we 
> even have a configure-time test for that. What is that about? Gnulib 
> doesn't have that, and it's certainly not for the MS-Windows build.

res_init originally had to do with the ancient (pre-2000) BIND 
interfaces that were not thread-safe. Emacs doesn't use those so we 
don't need to worry about them. More recently, res_init was used to kick 
glibc into re-reading /etc/resolv.conf. That has been obsolete for years 
too, with the emergence of nscd. Nowadays calling res_init merely slows 
Emacs down so Emacs should stop doing it, and I installed the attached 
patch into master.

> The current w32 code in Emacs wraps each network-related function with 
> a wrapper that tracks sockets and file descriptors they use, 
> translates socket errors to errno values, and does other important 
> stuff. The code also arranges for dynamically loading the socket 
> library only when actually needed. So replacing just one function will 
> certainly not work well, and replacing them all sounds like a lot of 
> work for very little gain. So I think a better way forward would be to 
> implement getaddrinfo wrapper in w32.c, complete with the fallback we 
> have in process.c (and maybe also borrowing some ideas from Gnulib).

Gnulib also tracks file descriptors in its substitute functions, I 
presume for similar reasons. At some point perhaps this should be 
unified with what Emacs does, but obviously this is not high priority.

> When this is done, we can install your patch for whatever other 
> systems which still don't have getaddrinfo (if there are such systems 
> that we still support). Writing such a getaddrinfo wrapper is easy, 
> and I expect it to be done soon enough, so please wait with your patch 
> until then. 

Sounds good.