[vlc-devel] [RFC] fix multiple definition of `inet_pton' when including microdns.h on WIN32

[Steve Lhomme]

Hi,

On 2019-07-19 6:04, Roland Bewick wrote:
> 
> Hi, I'm looking to use the inet_pton function within 
> modules\services_discovery\microdns.c
> 
> Unfortunately it looks to be defined twice when I cross compile for 
> Windows:
> 
> 1. in libmicrodns (compat/inet.c) - will only be declared if defined 
> (_WIN32) && !defined(HAVE_INET_NTOP)

On my win32 cross compilation (clang + mingw32) HAVE_INET_NTOP is set to 
1 so this code is never compiled.

> 2. in libws2_32.a (I think from including winsock2.h?)
> 
> /opt/gcc-x86_64-w64-mingw32/x86_64-w64-mingw32/lib/libws2_32.a(dywbs00169.o):(.text+0x0): 
> multiple definition of `inet_pton'
> /win64/vlc/contrib/x86_64-w64-mingw32/lib/libmicrodns.a(inet.o):/win64/libmicrodns/build/../compat/inet.c:60: 
> first defined here

When building VLC with the same configuration HAVE_INET_PTON is set and 
thus the compat function is never built either. The ws2_32 one is used.

So it seems rather an issue in your toolchain/build script. Are you 
using MSVC ? The 3.0 branch ?

> I've commented out the contents of the compat/inet.c file and 
> successfully VLC with the modified libmicrodns.
> 
> Is it ok to add a patch to contrib\src\microdns (see example below), or 
> is there a better way? Is it because it's linking libmicrodns 
> before//libws2_32 rather than after?
> 
> Thanks,
> 
> Roland
> 
> 
>  From e364a3201b30e88236dd62c892e9cb24e9c36fb2 Mon Sep 17 00:00:00 2001
> From: Roland Bewick <roland.bewick at gmail.com>
> Date: Thu, 18 Jul 2019 11:55:59 +0700
> Subject: [PATCH] remove unneeded inet compatibility
> 
> ---
>   compat/inet.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/compat/inet.c b/compat/inet.c
> index 2983e4d..9c2dfb8 100644
> --- a/compat/inet.c
> +++ b/compat/inet.c
> @@ -27,7 +27,7 @@
>   #include "compat.h"
>   #include "utils.h"
> 
> -#if defined (_WIN32) && !defined(HAVE_INET_NTOP)
> +/*#if defined (_WIN32) && !defined(HAVE_INET_NTOP)
>   const char *
>   inet_ntop(int af, const void *src, char *dst, socklen_t size)
>   {
> @@ -67,4 +67,4 @@ int inet_pton (int af, const char *src, void *dst)
>       errno = EAFNOSUPPORT;
>       return -1;
>   }
> -#endif // _WIN32 && !inet_ntop
> +#endif // _WIN32 && !inet_ntop */
> -- 
> 2.17.1
> 
> 
> 
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel
>