Apache: The Definitive Guide, 3rd Edition

Porting to Apache 2.0

In addition to the earlier discussion on how to write a module from scratch for Apache 2.0, which is broadly the same as for 1.x, we’ll show how to port one.

First of all, it is probably easiest to compile the module using apxs (although we are not keen on this approach, it is definitely the easiest, sadly). You’ll need to have configured Apache like this:

./configure --enable-so

Then compiling mod_reveal is easy:

apxs -c mod_reveal.c

This will, once its working, yield .libs/mod_reveal.so (use the -i option, and apxs will obligingly install it in /usr/local/apache2/lib). However, compiling the Apache 1.x version of mod_reveal produces a large number of errors (note that you might save yourself some agony by adding -Wc,-Wall and -Wc,-Werror to the command line). The first problem is that some headers have been split up and moved around. So, we had to add:

#include "http_request.h"

to get the definition for server_rec.

Also, many data structures and functions in Apache 1.3 had names that could cause conflict with other libraries. So, they have all been prefixed in an attempt to make them unique. The prefixes are ap_, apr_, and apu_ depending on whether they belong to Apache, APR, or APR-util. If they are data structures, they typically have also had _t appended. So, pool has become apr_pool_t. Many functions have also moved from ap_ to apr_; for example, ap_pstrcat() has become apr_pstrcat() and now needs the header apr_strings.h.

Functions that didn’t take pool ...