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From Graham Leggett <>
Subject Re: Defining mandatory parameters for Apache modules
Date Thu, 13 Aug 2009 13:46:07 GMT
Raj Iyer wrote:

> The Apache web server on start up iterates through the list of
> configuration directives and invokes the associated module handler for
> each directive.
> For e.g. if module A has handlers for directives D1 and D2, then the
> httpd process on start up will invoke the handlers within module A when
> it encounters D1 and D2 in httpd.conf.
> However, what is the best way to find out missing mandatory parameters
> from within the module. For e.g. if a directive D3 is mandatory for the
> module to work, then how can the module on initialization guarantee that
> this configuration parameter is provided?
> I do not want to provide a default value for this mandatory
> configuration directive and also, I do not want to check whether this
> mandatory directive is defined or not while handling each request.

There are lots of examples of this in the httpd source code.

When a directive is parsed, and the directive was parsed successfully,
the parse will return NULL, and the config will continue onto the next

When a directive has a fatal error in it, and you don't want to
continue, return a string containing the error message you want to give
to the end user explaining why that particular line is wrong.

httpd will automatically stop config file parsing at that point, and
return the fatal error you just provided.


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