Yesterday I've received a inquiry from Harel Haruda about my example of Apache 2.2 modules for linux, he was having some trouble trying to let Apache load its modules.

My former example was compiled using FPC 2.2.2 on an i386 PC with Debian Linux, now I'm using Ubuntu 9.10 for x86-64 with FPC 2.2.3.


One very important change es in FPC 2.2.3, variables and functions have to be marked to be exportable, with the keyword "export". In previous versions, all functions and variables where exported automatically. I'd read this in the FPC Wiki.

The new code:

{*******************************************

*  Test library of the Apache Pascal Headers

********************************************}

library mod_helloworld;



{$mode objfpc}{$H+}



uses SysUtils, httpd {$ifndef Apache1_3}, apr{$endif};



var

 test_module: module;  export;

 default_module_ptr: Pmodule;



const

  MODULE_NAME = 'mod_helloworld.so';

  HANDLER = 'helloworld-handler';



exports test_module;

 

{****************************************************

*  Handles apache requests

*****************************************************}

function DefaultHandler(r: Prequest_rec): Integer; cdecl;

var

  RequestedHandler: string;

begin

  RequestedHandler := r^.handler;



  ap_log_error(MODULE_NAME, 54, APLOG_NOERRNO or APLOG_NOTICE,

   0, r^.server, 'mod_hello: %s', [PChar('Before content is output')]);



  if not SameText(RequestedHandler, 'helloworld-handler') then

  begin

    Result := DECLINED;

    Exit;

  end;



   ap_set_content_type(r, 'text/html');

 

  { If the request is for a header only, and not a request for

   the whole content, then return OK now. We don't have to do

   anything else. }

  if (r^.header_only <> 0) then

  begin

    Result := OK;

    Exit;

  end;



  { Now we just print the contents of the document using the

   ap_rputs and ap_rprintf functions. More information about

   the use of these can be found in http_protocol.inc }

  ap_rputs('' + LineEnding, r);

  ap_rputs('' + LineEnding, r);

  ap_rputs('' + LineEnding, r);

  ap_rputs('' + LineEnding, r);

  ap_rputs('' + LineEnding ,r);

  ap_rputs('
Hello world
' + LineEnding, r);

  ap_rputs('This is the first Apache Module working with the new binding from Free Pascal' + LineEnding, r);

  ap_rputs('' + LineEnding, r);



  { We can either return OK or DECLINED at this point. If we return

         * OK, then no other modules will attempt to process this request }

  Result := OK;

end;



{***************************************************

*  Registers the hooks

****************************************************}

procedure RegisterHooks(p: Papr_pool_t); cdecl;

begin

  ap_hook_handler(@DefaultHandler, nil, nil, APR_HOOK_MIDDLE);

end;



{***************************************************

*  Library initialization code

****************************************************}

begin

  default_module_ptr := @test_module;

  FillChar(default_module_ptr^, SizeOf(default_module_ptr^), 0);



   STANDARD20_MODULE_STUFF(test_module);



    with test_module do

    begin

      name := MODULE_NAME;

      register_hooks := @RegisterHooks;

    end;

end.

To compile this, I used this (long) command line:

fpc -fPIC -B -WR -Xs -XX -Fu/usr/share/fpcsrc/2.2.4/packages/httpd22/src -Fu/usr/share/fpcsrc/2.2.4/packages/httpd22/src/apr -Fu/usr/share/fpcsrc/2.2.4/packages/httpd22/src/aprutil -Fu/usr/share/fpcsrc/2.2.4/src/apriconv mod_helloworld.pas

This will create a "libmod_helloworld.so" library.

Then, I had to copy it to /usr/lib64/apache2/modules directory changing its name to mod_helloworld.so:

cp libmod_helloworld.so /usr/lib64/apache2/modules/mod_helloworld.so

The next step, as usual, is to let Apache know from where to load the new module:

File /etc/apache2/mods-available/helloworld.load

LoadModule test_module /usr/lib64/apache2/modules/mod_helloworld.so

File /etc/apache2/mods-available/helloworld.conf

<Location /hello>

  SetHandler helloworld-handler

</Location>

Now, I created a symlink to those files, from the directory /etc/apache2/mods-enabled:

ln -s /etc/apache2/mods-available/helloworld.conf /etc/apache2/mods-enabled/helloworld.conf

ln -s /etc/apache2/mods-available/helloworld.load /etc/apache2/mods-enabled/helloworld.load

The last step is to restart Apache and test the module:

sudo apache2ctl start

To test the module go to http://localhost/hello