Converting Modules from Apache 1.3 to Apache 2.0

This is a first attempt at writing the lessons I learned when trying to convert the modmmapstatic

module to Apache 2.0. It's by no means definitive and probably won't even be correct in some ways, but it's a start.

These now need to be of type aprstatust

and return a value of that type. Normally the return value will be APR_SUCCESS

unless there is some need to signal an error in the cleanup. Be aware that even though you signal an error not all code yet checks and acts upon the error.

These should now be renamed to better signify where they sit in the overall process. So the name gets a small change from mmap_init

. The arguments passed have undergone a radical change and now look like

A lot of the data types have been moved into the APR. This means that some have had a name change, such as the one shown above. The following is a brief list of some of the changes that you are likely to have to make.

The new architecture uses a series of hooks to provide for calling your functions. These you'll need to add to your module by way of a new function, static void register_hooks(void)

. The function is really reasonably straightforward once you understand what needs to be done. Each function that needs calling at some stage in the processing of a request needs to be registered, handlers do not. There are a number of phases where functions can be added, and for each you can specify with a high degree of control the relative order that the function will be called in.

static void registerhooks(void) { static const char * const aszPre[]={ "httpcore.c",NULL }; aphookpostconfig(mmappostconfig,NULL,NULL,HOOKMIDDLE); aphooktranslatename(mmapstaticxlat,aszPre,NULL,HOOKLAST); };

This registers 2 functions that need to be called, one in the post_config

stage (virtually every module will need this one) and one for the translate_name

phase. note that while there are different function names the format of each is identical. So what is the format?

phasename(functionname, predecessors, successors, position);

There are 3 hook positions defined...

To define the position you use the position and then modify it with the predecessors and successors. Each of the modifiers can be a list of functions that should be called, either before the function is run (predecessors) or after the function has run (successors).

case I didn't care about the post_config

must be called after the core module had done its name translation, hence the use of the aszPre to define a modifier to the position HOOK_LAST

There are now a lot fewer stages to worry about when creating your module definition. The old definition looked like

module MODULEVAREXPORTmodulenamemodule = { STANDARDMODULESTUFF, / initializer / / dir config creater / / dir merger --- default is to override / / server config / / merge server config / / command handlers / / handlers / / filename translation / / checkuserid / / check auth / / check access / / typechecker / / fixups / / logger / / header parser / / childinit / / child_exit / / post read-request / };

The new structure is a great deal simpler...

module MODULEVAREXPORTmodulenamemodule = { STANDARD20MODULESTUFF, / create per-directory config structures / / merge per-directory config structures / / create per-server config structures / / merge per-server config structures / / command handlers / / handlers / / register hooks / };

Some of these read directly across, some don't. I'll try to summarise what should be done below.

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