From mboxrd@z Thu Jan  1 00:00:00 1970
From: john at keeping.me.uk (John Keeping)
Date: Sun, 23 Oct 2016 16:55:39 +0100
Subject: Linking cgit with Lua using -Wl,-E
In-Reply-To: <564914cc-2ae6-ad15-f40c-4f033788999c@aegee.org>
References: <7dcc34c2-6494-137b-79cb-0a3eb664e49a@aegee.org>
 <20161016115547.GG22407@john.keeping.me.uk>
 <564914cc-2ae6-ad15-f40c-4f033788999c@aegee.org>
Message-ID: <20161023155539.GB3542@john.keeping.me.uk>

I assume it's possible to build a shared library; I get both shared and
static installed by my package manager.

It looks like there is some performance concern about using a shared
libary for Lua[1], but I doubt performance is critical for most uses
with CGit so I would recommend building and linking to the Lua shared
library if possible.

If you need to link to the static library, I think it will be safer to
use:

	-rdynamic -fvisibility=hidden

but that will still expose all of the symbols from libgit.a, which was
not designed to be used as a library by third-party code and thus does
not prefix its symbols, so you still have to be wary of symbol
collisions with other libraries.

[1] http://article.gmane.org/gmane.comp.lang.lua.general/18519

On Fri, Oct 21, 2016 at 09:54:23AM +0200, ????? ???????? wrote:
> liblua is linked statically. This is what you get, when you compile
> Lua from source (no liblua.so).
> 
> On 10/16/2016 01:55 PM, John Keeping wrote:
> > On Sun, Oct 16, 2016 at 07:30:08AM +0200, ????? ???????? wrote:
> >> on my system I wanted to link cgit with lua, so that lua can load the
> >> (lua)crypto.so module.  For this to work the symbol lua_gettop has to
> >> be exported by cgit.  I managed this by passing "-Wl,-E" to the
> >> linker, when compiling cgit.
> >
> > How are you linking to liblua?  I thought we normally linked that
> > dynamically so the symbol should be exported from the shared library
> > even if the cgit binary does not export symbols.
> >