497 lines
19 KiB
Markdown
497 lines
19 KiB
Markdown
Ikiwiki's plugin interface allows all kinds of useful [[plugins]] to be
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written to extend ikiwiki in many ways. Despite the length of this page,
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it's not really hard. This page is a complete reference to everything a
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plugin might want to do. There is also a quick [[tutorial]].
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[[toc levels=2]]
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## Types of plugins
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Most ikiwiki [[plugins]] are written in perl, like ikiwiki. This gives the
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plugin full access to ikiwiki's internals, and is the most efficient.
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However, plugins can actually be written in any language that supports XML
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RPC. These are called [[external]] plugins.
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A plugin written in perl is a perl module, in the `IkiWiki::Plugin`
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namespace. The name of the plugin is typically in lowercase, such as
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`IkiWiki::Plugin::inline`. Ikiwiki includes a `IkiWiki::Plugin::skeleton`
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that can be fleshed out to make a useful plugin.
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`IkiWiki::Plugin::pagecount` is another simple example. All perl plugins
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should `use IkiWiki` to import the ikiwiki plugin interface. It's a good
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idea to include the version number of the plugin interface that your plugin
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expects: `use IkiWiki 2.00`.
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An external plugin is an executable program. It can be written in any
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language. Its interface to ikiwiki is via XML RPC, which it reads from
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ikiwiki on its standard input, and writes to ikiwiki on its standard
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output. For more details on writing external plugins, see [[external]].
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Despite these two types of plugins having such different interfaces,
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they're the same as far as how they hook into ikiwiki. This document will
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explain how to write both sorts of plugins, albeit with an emphasis on perl
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plugins.
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## Considerations
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One thing to keep in mind when writing a plugin is that ikiwiki is a wiki
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*compiler*. So plugins influence pages when they are built, not when they
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are loaded. A plugin that inserts the current time into a page, for
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example, will insert the build time. Also, as a compiler, ikiwiki avoids
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rebuilding pages unless they have changed, so a plugin that prints some
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random or changing thing on a page will generate a static page that won't
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change until ikiwiki rebuilds the page for some other reason, like the page
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being edited.
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## Registering plugins
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Plugins should, when imported, call `hook()` to hook into ikiwiki's
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processing. The function uses named parameters, and use varies depending on
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the type of hook being registered -- see below. Note that a plugin can call
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the function more than once to register multiple hooks. All calls to
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`hook()` should be passed a "type" parameter, which gives the type of
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hook, a "id" paramter, which should be a unique string for this plugin, and
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a "call" parameter, which tells what function to call for the hook.
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An optional "last" parameter, if set to a true value, makes the hook run
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after all other hooks of its type. Useful if the hook depends on some other
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hook being run first.
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## Types of hooks
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In roughly the order they are called.
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### getopt
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hook(type => "getopt", id => "foo", call => \&getopt);
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This allows for plugins to perform their own processing of command-line
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options and so add options to the ikiwiki command line. It's called during
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command line processing, with @ARGV full of any options that ikiwiki was
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not able to process on its own. The function should process any options it
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can, removing them from @ARGV, and probably recording the configuration
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settings in %config. It should take care not to abort if it sees
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an option it cannot process, and should just skip over those options and
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leave them in @ARGV.
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### checkconfig
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hook(type => "checkconfig", id => "foo", call => \&checkconfig);
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This is useful if the plugin needs to check for or modify ikiwiki's
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configuration. It's called early in the startup process. The
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function is passed no values. It's ok for the function to call
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`error()` if something isn't configured right.
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### needsbuild
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hook(type => "needsbuild", id => "foo", call => \&needsbuild);
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This allows a plugin the manipulate the list of files that need to be
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built when the wiki is refreshed. The function is passed a reference to an
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array of pages that will be rebuilt, and can modify the array, either
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adding or removing files from it.
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### filter
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hook(type => "filter", id => "foo", call => \&filter);
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Runs on the raw source of a page, before anything else touches it, and can
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make arbitrary changes. The function is passed named parameters "page",
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"destpage", and "content". It should return the filtered content.
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### preprocess
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Adding a [[PreProcessorDirective]] is probably the most common use of a
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plugin.
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hook(type => "preprocess", id => "foo", call => \&preprocess);
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Replace "foo" with the command name that will be used inside brackets for
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the preprocessor directive.
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Each time the directive is processed, the referenced function (`preprocess`
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in the example above) is called, and is passed named parameters. A "page"
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parameter gives the name of the page that embedded the preprocessor
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directive, while a "destpage" parameter gives the name of the page the
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content is going to (different for inlined pages), and a "preview"
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parameter is set to a true value if the page is being previewed. All
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parameters included in the directive are included as named parameters as
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well. Whatever the function returns goes onto the page in place of the
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directive.
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An optional "scan" parameter, if set to a true value, makes the hook be
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called during the preliminary scan that ikiwiki makes of updated pages,
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before begining to render pages. This parameter should be set to true if
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the hook modifies data in `%links`. Note that doing so will make the hook
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be run twice per page build, so avoid doing it for expensive hooks.
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Note that if the [[htmlscrubber]] is enabled, html in
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[[PreProcessorDirective]] output is sanitised, which may limit what your
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plugin can do. Also, the rest of the page content is not in html format at
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preprocessor time. Text output by a preprocessor directive will be
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linkified and passed through markdown (or whatever engine is used to htmlize
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the page) along with the rest of the page.
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### htmlize
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hook(type => "htmlize", id => "ext", call => \&htmlize);
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Runs on the raw source of a page and turns it into html. The id parameter
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specifies the filename extension that a file must have to be htmlized using
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this plugin. This is how you can add support for new and exciting markup
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languages to ikiwiki.
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The function is passed named parameters: "page" and "content" and should
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return the htmlized content.
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### pagetemplate
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hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
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[[Templates|wikitemplate]] are filled out for many different things in
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ikiwiki, like generating a page, or part of a blog page, or an rss feed, or
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a cgi. This hook allows modifying the variables available on those
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templates. The function is passed named parameters. The "page" and
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"destpage" parameters are the same as for a preprocess hook. The "template"
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parameter is a [[cpan HTML::Template]] object that is the template that
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will be used to generate the page. The function can manipulate that
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template object.
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The most common thing to do is probably to call `$template->param()` to add
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a new custom parameter to the template.
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### templatefile
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hook(type => "templatefile", id => "foo", call => \&templatefile);
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This hook allows plugins to change the [[template|wikitemplate]] that is
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used for a page in the wiki. The hook is passed a "page" parameter, and
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should return the name of the template file to use, or undef if it doesn't
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want to change the default ("page.tmpl"). Template files are looked for in
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/usr/share/ikiwiki/templates by default.
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### sanitize
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hook(type => "sanitize", id => "foo", call => \&sanitize);
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Use this to implement html sanitization or anything else that needs to
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modify the body of a page after it has been fully converted to html.
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The function is passed named parameters: "page" and "content", and
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should return the sanitized content.
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### format
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hook(type => "format", id => "foo", call => \&format);
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The difference between format and sanitize is that sanitize only acts on
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the page body, while format can modify the entire html page including the
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header and footer inserted by ikiwiki, the html document type, etc.
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The function is passed named parameters: "page" and "content", and
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should return the formatted content.
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### delete
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hook(type => "delete", id => "foo", call => \&delete);
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Each time a page or pages is removed from the wiki, the referenced function
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is called, and passed the names of the source files that were removed.
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### change
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hook(type => "change", id => "foo", call => \&render);
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Each time ikiwiki renders a change or addition (but not deletion) to the
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wiki, the referenced function is called, and passed the names of the
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source files that were rendered.
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### cgi
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hook(type => "cgi", id => "foo", call => \&cgi);
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Use this to hook into ikiwiki's cgi script. Each registered cgi hook is
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called in turn, and passed a CGI object. The hook should examine the
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parameters, and if it will handle this CGI request, output a page (including the http headers) and
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terminate the program.
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### auth
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hook(type => "auth", id => "foo", call => \&auth);
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This hook can be used to implement a different authentication method than
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the standard web form. When a user needs to be authenticated, each registered
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auth hook is called in turn, and passed a CGI object and a session object.
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If the hook is able to authenticate the user, it should set the session
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object's "name" parameter to the authenticated user's name. Note that
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if the name is set to the name of a user who is not registered,
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a basic registration of the user will be automatically performed.
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### sessioncgi
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hook(type => "sessioncgi", id => "foo", call => \&sessioncgi);
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Unlike the cgi hook, which is run as soon as possible, the sessioncgi hook
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is only run once a session object is available. It is passed both a CGI
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object and a session object. To check if the user is in fact signed in, you
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can check if the session object has a "name" parameter set.
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### canedit
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hook(type => "canedit", id => "foo", call => \&pagelocked);
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This hook can be used to implement arbitrary access methods to control when
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a page can be edited using the web interface (commits from revision control
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bypass it). When a page is edited, each registered canedit hook is called
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in turn, and passed the page name, a CGI object, and a session object.
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If edit can proceed, the hook should return "". If the edit is not allowed
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by this hook, the hook should return an error message for the user to see.
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If the hook has no opinion about whether the edit can proceed, return
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`undef`, and the next plugin will be asked to decide.
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### formbuilder
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hook(type => "formbuilder_setup", id => "foo", call => \&formbuilder_setup);
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hook(type => "formbuilder", id => "foo", call => \&formbuilder);
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These hooks allow tapping into the parts of ikiwiki that use [[cpan
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CGI::FormBuilder]] to generate web forms. These hooks are passed named
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parameters: `cgi`, `session`, and `form`. These are, respectively, the
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`CGI` object, the user's `CGI::Session`, and a `CGI::FormBuilder`.
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Each time a form is set up, the `formbuilder_setup` hook is called.
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Typically the `formbuilder_setup` hook will check the form's title, and if
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it's a form that it needs to modify, will call various methods to
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add/remove/change fields, tweak the validation code for the fields, etc. It
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will not validate or display the form.
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Form validation and display can be overridden by the formbuilder hook.
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By default, ikiwiki will do a basic validation and display of the form,
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but if this hook is registered, it will stop that and let the hook take
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over. This hook is passed an additional named parameter: `buttons` is an
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array of the submit buttons for the form.
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### savestate
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hook(type => "savestate", id => "foo", call => \&savestate);
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This hook is called wheneven ikiwiki normally saves its state, just before
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the state is saved. The function can save other state, modify values before
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they're saved, etc.
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## Plugin interface
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To import the ikiwiki plugin interface:
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use IkiWiki '1.00';
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This will import several variables and functions into your plugin's
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namespace. These variables and functions are the ones most plugins need,
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and a special effort will be made to avoid changing them in incompatible
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ways, and to document any changes that have to be made in the future.
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Note that IkiWiki also provides other variables and functions that are not
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exported by default. No guarantee is made about these in the future, so if
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it's not exported, the wise choice is to not use it.
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### %config
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A plugin can access the wiki's configuration via the `%config`
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hash. The best way to understand the contents of the hash is to look at
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[[ikiwiki.setup]], which sets the hash content to configure the wiki.
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### Other variables
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If your plugin needs to access data about other pages in the wiki. It can
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use the following hashes, using a page name as the key:
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* `%links` lists the names of each page that a page links to, in an array
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reference.
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* `%destsources` contains the name of the source file used to create each
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destination file.
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* `%pagesources` contains the name of the source file for each page.
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Also, the %IkiWiki::version variable contains the version number for the
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ikiwiki program.
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### Library functions
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#### `hook(@)`
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Hook into ikiwiki's processing. See the discussion of hooks above.
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Note that in addition to the named parameters described above, a parameter
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named `no_override` is supported, If it's set to a true value, then this hook
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will not override any existing hook with the same id. This is useful if
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the id can be controled by the user.
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#### `debug($)`
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Logs a debugging message. These are supressed unless verbose mode is turned
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on.
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#### `error($;$)`
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Aborts with an error message. If the second parameter is passed, it is a
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function that is called after the error message is printed, to do any final
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cleanup.
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Note that while any plugin can use this for a fatal error, plugins should
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try to avoid dying on bad input, as that will halt the entire wiki build
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and make the wiki unusable. So for example, if a [[PreProcessorDirective]]
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is passed bad parameters, it's better to return an error message, which can
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appear on the wiki page, rather than calling error().
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#### `template($;@)`
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Creates and returns a [[cpan HTML::Template]] object. The first parameter
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is the name of the file in the template directory. The optional remaining
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parameters are passed to `HTML::Template->new`.
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#### `htmlpage($)`
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Passed a page name, returns the base name that will be used for a the html
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page created from it. (Ie, it appends ".html".)
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#### `add_depends($$)`
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Makes the specified page depend on the specified [[PageSpec]].
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#### `pagespec_match($$;@)`
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Passed a page name, and [[PageSpec]], returns true if the [[PageSpec]]
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matches the page.
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Additional named parameters can be passed, to further limit the match.
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The most often used is "location", which specifies the location the
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PageSpec should match against. If not passed, relative PageSpecs will match
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relative to the top of the wiki.
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#### `bestlink($$)`
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Given a page and the text of a link on the page, determine which
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existing page that link best points to. Prefers pages under a
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subdirectory with the same name as the source page, failing that
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goes down the directory tree to the base looking for matching
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pages, as described in [[SubPage/LinkingRules]].
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#### `htmllink($$$;@)`
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Many plugins need to generate html links and add them to a page. This is
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done by using the `htmllink` function. The usual way to call
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`htmlllink` is:
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htmllink($page, $page, $link)
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Why is `$page` repeated? Because if a page is inlined inside another, and a
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link is placed on it, the right way to make that link is actually:
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htmllink($page, $destpage, $link)
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Here `$destpage` is the inlining page. A `destpage` parameter is passed to
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some of the hook functions above; the ones that are not passed it are not used
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during inlining and don't need to worry about this issue.
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After the three required parameters, named parameters can be used to
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control some options. These are:
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* noimageinline - set to true to avoid turning links into inline html images
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* forcesubpage - set to force a link to a subpage
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* linktext - set to force the link text to something
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* anchor - set to make the link include an anchor
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* rel - set to add a rel attribute to the link.
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#### `readfile($;$)`
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Given a filename, reads and returns the entire file.
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The optional second parameter, if set to a true value, makes the file be read
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in binary mode.
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A failure to read the file will result in it dying with an error.
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#### `writefile($$$;$$)`
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Given a filename, a directory to put it in, and the file's content,
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writes a file.
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The optional fourth parameter, if set to a true value, makes the file be
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written in binary mode.
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The optional fifth parameter can be used to pass a function reference that
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will be called to handle writing to the file. The function will be called
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and passed a file descriptor it should write to, and an error recovery
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function it should call if the writing fails. (You will not normally need to
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use this interface.)
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A failure to write the file will result in it dying with an error.
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If the destination directory doesn't exist, it will first be created.
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#### `will_render($$)`
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Given a page name and a destination file name (not including the base
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destination directory), register that the page will result in that file
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being rendered. It's important to call this before writing to any file in
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the destination directory.
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#### `pagetype($)`
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Given the name of a source file, returns the type of page it is, if it's
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a type that ikiwiki knowns how to htmlize. Otherwise, returns undef.
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#### `pagename($)`
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Given the name of a source file, returns the name of the wiki page
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that corresponds to that file.
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#### `srcfile($)`
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Given the name of a source file in the wiki, searches for the file in
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the source directory and the underlay directory, and returns the full
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path to the first file found.
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#### `displaytime($)`
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Given a time, formats it for display.
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#### `gettext`
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This is the standard gettext function, although slightly optimised.
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#### `urlto($$)`
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Construct a relative url to the first parameter from the page named by the
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second. The first parameter can be either a page name, or some other
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destination file, as registered by `will_render`.
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#### `targetpage($$)`
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Passed a page and an extension, returns the filename that page will be
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rendered to.
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## RCS plugins
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ikiwiki's support for revision control systems also uses pluggable perl
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modules. These are in the `IkiWiki::RCS` namespace, for example
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`IkiWiki::RCS::svn`.
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Each RCS plugin must support all the `IkiWiki::rcs_*` functions.
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See IkiWiki::RCS::Stub for the full list of functions. It's ok if
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`rcs_getctime` does nothing except for throwing an error.
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See [[about_RCS_backends]] for some more info.
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## PageSpec plugins
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It's also possible to write plugins that add new functions to
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[[PageSpecs|PageSpec]]. Such a plugin should add a function to the
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IkiWiki::PageSpec package, that is named `match_foo`, where "foo()" is
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how it will be accessed in a [[PageSpec]]. The function will be passed
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two parameters: The name of the page being matched, and the thing to match
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against. It may also be passed additional, named parameters. It should return
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a IkiWiki::SuccessReason object if the match succeeds, or an
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IkiWiki::FailReason object if the match fails.
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