Building and loading of modules/plugins in XFCE

[Maarten Boekhold]

Hi all,

While porting XFCE to cygwin, I learned about the many wonderful 
peculiarities of building loadable modules on cygwin/windows.

There's a mysterious interplay between the name of the library in the 
Makefile.am, the LDFLAGS, the resulting library name and the install 
location of the library:

(1) plugin_LTLIBRARIES = libxfce4_combo.la

==> the loadable module will be named 'cygxfce4_combo.dll'

(2) plugin_LTLIBRARIES = keyboard_plugin.la

==> the loadable module will be named 'keyboard_plugin.dll'

(3) '-module' used in LDFLAGS

==> the loadable module will be installed in the specified install directory

(4) *no* '-module' used in LDFLAGS

==> the loadable module will be installed in ../bin (relative to the 
specified install directory)

As many of the XFCE components assume that a loadable module is (1) 
named 'libXXXX.<SOEXT>', and (2) located in a specific directory, some 
of the modules fail to load, because the generated filenames (for 
g_module_open) don't match the actual library names (btw. xfce4-panel 
isn't affected by this, as it 'walks' the directory to get the actual 
filenames of the plugins, same probably for mcs-manager).

So, we'll need to make sure that (1) all modules are built/installed 
with the '-module' flag (for one, libxfcegui4 needs to be fixed), and 
(2) the correct filenames are constructed for passing to g_module_open.

In order to accomplish (2), it is sufficient to consistently use 
g_module_build_path(<directory>, <module name>), where <module name> is 
*without* a 'lib' prefix *and without* a <SOEXT> suffix. The platform 
specific implementation of g_module_build_path will make sure that a 
correct library name is created.

At the least, xfce-utils/xfrun (libxfce4_combo) and xffm 
(libxfce4_combo, libxfce4_mime) need fixing in this respect. Likely 
there is more then these apps, and I would like to ask all authors if 
they can spent a few minutes thinking which other pieces of XFCE might 
be affected by this.

If you know of other places where library names are generated, please 
drop me a mail, and I'll generate patches to make this portable to cygwin.

Kind regards,

Maarten