…just another hippy blog

Coffee … break !
Originally uploaded by Christiane Michaud.

Sorry folks, I was lying. This post is not about wynona. I’m really really sorry.
I have spent the whole day trying to build an apache module using Qt and qmake so I have to blog about my success.

I know, the guys at apache (btw. I’m really impressed by their work) advise against writing C++ modules or linking shared libraries, but I’ll have to do that for a project I’m working on at Clickout Ltd. so we’ll have to discuss those issues some day.

Nevertheless, the traditional mod_helloworld buit with no hassle on windows but there was no way to make it work on Linux/GCC so I had quite some fun figuring out the issue. So, here is a quick tutorial

For starters, you’ll need to setup your Qt project to build either a dll or a plugin. I used the latter so I won’t have all those symlinks typical for *nix libraries.
The you’ll need to get it to work is add the path to your system’s apache2 and apr-1.0 header files to the includepath:

INCLUDEPATH += /usr/include/apr-1.0
INCLUDEPATH += /usr/include/apache2

Now comes the tricky part. Qt will usually tell g++ to report undefined references in object files by passing the -Wl,–no-undefined parameter to the linker.
It took me hours to realize that this was the issue. Apache modules are usually built using a C compiler and libtool or even the apxs[2] Apache perl script that does all the stuff for you.

It also took me some time to figure why I was not succeeding in removing that –no-undefined flag using the QMAKE* variables. So, this is what I came up with after reading the g++ mkspec source code:

QMAKE_LFLAGS -= -Wl,–no-undefined

Now, I am pretty sure I tried QMAKE_LFLAGS before and it would not work, but well you know how these things work.
So, this will build a file called libTARGET_NAME.so.
Now follow the usual steps to install it and restart apache

You can take the helloworld module source code from here:
http://www.cb1inc.com/2007/12/24/creating-a-hello-world-apache-module-with-kdevelop-on-ubuntu

then just add some QString and whatever else

UPDATE: Apache 2.x will disable strtoul from the C standard library but your MS VC compiler is very likely to use it, so you will get some error with strtoul_is_not_a_portable_function_use_strtol_instead. Just add an #undef strtoul *after* #including httpd.h and *before* #including any code that might use the cstdlib, like QString.