gajim: Add support for LaTeX markup.

This needed a bit of patching the paths to the latex and dvipng executables.

In addition, we also address a small bug by using sed:

tmpfd, tmppng = mkstemp(prefix='gajim_tex', suffix='.png')
tmpfd.close()

This obviously won't work, because mkstemp() actually returns a file descriptor
_number_ and not a Python file object.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/applications/networking/instant-messengers/gajim/default.nix

@@ -6,6 +6,7 @@
 , enableE2E ? true
 , enableRST ? true
 , enableSpelling ? true, gtkspell ? null
+, enableLaTeX ? false, texLive ? null
 }:
 
 assert enableJingle -> farstream != null && gst_plugins_bad != null
@@ -13,6 +14,7 @@ assert enableJingle -> farstream != null && gst_plugins_bad != null
 assert enableE2E -> pythonPackages.pycrypto != null;
 assert enableRST -> pythonPackages.docutils != null;
 assert enableSpelling -> gtkspell != null;
+assert enableLaTeX -> texLive != null;
 
 with stdenv.lib;
 
@@ -53,6 +55,11 @@ stdenv.mkDerivation rec {
   '' + optionalString enableSpelling ''
     sed -i -e 's|=.*find_lib.*|= "${gtkspell}/lib/libgtkspell.so"|'   \
       src/gtkspell.py
+  '' + optionalString enableLaTeX ''
+    sed -i -e "s|try_run(.'dvipng'|try_run(['${texLive}/bin/dvipng'|" \
+           -e "s|try_run(.'latex'|try_run(['${texLive}/bin/latex'|"   \
+           -e 's/tmpfd.close()/os.close(tmpfd)/'                      \
+           src/common/latex.py
   '';
 
   buildInputs = [
@@ -63,7 +70,8 @@ stdenv.mkDerivation rec {
     pyopenssl pythonDBus
   ] ++ optionals enableJingle [ farstream gst_plugins_bad libnice ]
     ++ optional enableE2E pythonPackages.pycrypto
-    ++ optional enableRST pythonPackages.docutils;
+    ++ optional enableRST pythonPackages.docutils
+    ++ optional enableLaTeX texLive;
 
   postInstall = ''
     install -m 644 -t "$out/share/gajim/icons/hicolor" \