-ikiwiki [[plugins]] are written in perl. Each plugin is a perl module, in
-the `IkiWiki::Plugin` namespace. The name of the plugin is typically in
-lowercase, such as `IkiWiki::Plugin::inline`. Ikiwiki includes a
-`IkiWiki::Plugin::skeleton` that can be fleshed out to make a useful
-plugin. `IkiWiki::Plugin::pagecount` is another simple example.
+Ikiwiki's plugin interface allows all kinds of useful [[plugins]] to be
+written to extend ikiwiki in many ways. Despite the length of this page,
+it's not really hard. This page is a complete reference to everything a
+plugin might want to do. There is also a quick [[tutorial]].
[[toc levels=2]]
+## Types of plugins
+
+Most ikiwiki [[plugins]] are written in perl, like ikiwiki. This gives the
+plugin full access to ikiwiki's internals, and is the most efficient.
+However, plugins can actually be written in any language that supports XML
+RPC. These are called [[external]] plugins.
+
+A plugin written in perl is a perl module, in the `IkiWiki::Plugin`
+namespace. The name of the plugin is typically in lowercase, such as
+`IkiWiki::Plugin::inline`. Ikiwiki includes a `IkiWiki::Plugin::skeleton`
+that can be fleshed out to make a useful plugin.
+`IkiWiki::Plugin::pagecount` is another simple example. All perl plugins
+should `use IkiWiki` to import the ikiwiki plugin interface. It's a good
+idea to include the version number of the plugin interface that your plugin
+expects: `use IkiWiki 2.00`.
+
+An external plugin is an executable program. It can be written in any
+language. Its interface to ikiwiki is via XML RPC, which it reads from
+ikiwiki on its standard input, and writes to ikiwiki on its standard
+output. For more details on writing external plugins, see [[external]].
+
+Despite these two types of plugins having such different interfaces,
+they're the same as far as how they hook into ikiwiki. This document will
+explain how to write both sorts of plugins, albeit with an emphasis on perl
+plugins.
+
## Considerations
One thing to keep in mind when writing a plugin is that ikiwiki is a wiki
## Registering plugins
-All plugins should `use IkiWiki` to import the ikiwiki plugin interface.
-It's a good idea to include the version number of the plugin interface that
-your plugin expects: `use IkiWiki 2.00`
-
Plugins should, when imported, call `hook()` to hook into ikiwiki's
processing. The function uses named parameters, and use varies depending on
the type of hook being registered -- see below. Note that a plugin can call
the function more than once to register multiple hooks. All calls to
`hook()` should be passed a "type" parameter, which gives the type of
hook, a "id" paramter, which should be a unique string for this plugin, and
-a "call" parameter, which is a reference to a function to call for the
-hook.
+a "call" parameter, which tells what function to call for the hook.
An optional "last" parameter, if set to a true value, makes the hook run
after all other hooks of its type. Useful if the hook depends on some other
function is passed no values. It's ok for the function to call
`error()` if something isn't configured right.
+### refresh
+
+ hook(type => "refresh", id => "foo", call => \&refresh);
+
+This hook is called just before ikiwiki scans the wiki for changed files.
+It's useful for plugins that need to create or modify a source page. The
+function is passed no values.
+
### needsbuild
hook(type => "needsbuild", id => "foo", call => \&needsbuild);
-This allows a plugin the manipulate the list of files that need to be
+This allows a plugin to manipulate the list of files that need to be
built when the wiki is refreshed. The function is passed a reference to an
array of pages that will be rebuilt, and can modify the array, either
adding or removing files from it.
### preprocess
-Adding a [[PreProcessorDirective]] is probably the most common use of a
-plugin.
+Adding a [[ikiwiki/PreProcessorDirective]] is probably the most common use
+of a plugin.
hook(type => "preprocess", id => "foo", call => \&preprocess);
called during the preliminary scan that ikiwiki makes of updated pages,
before begining to render pages. This parameter should be set to true if
the hook modifies data in `%links`. Note that doing so will make the hook
-be run twice per page build, so avoid doing it for expensive hooks.
+be run twice per page build, so avoid doing it for expensive hooks. (As an
+optimisation, if your preprocessor hook is called in a void contets, you
+can assume it's being run in scan mode.)
Note that if the [[htmlscrubber]] is enabled, html in
-[[PreProcessorDirective]] output is sanitised, which may limit what your
-plugin can do. Also, the rest of the page content is not in html format at
-preprocessor time. Text output by a preprocessor directive will be
-linkified and passed through markdown (or whatever engine is used to htmlize
-the page) along with the rest of the page.
+[[ikiwiki/PreProcessorDirective]] output is sanitised, which may limit what
+your plugin can do. Also, the rest of the page content is not in html
+format at preprocessor time. Text output by a preprocessor directive will
+be linkified and passed through markdown (or whatever engine is used to
+htmlize the page) along with the rest of the page.
+
+### linkify
+
+ hook(type => "linkify", id => "foo", call => \&linkify);
+
+This hook is called to convert [[WikiLinks|WikiLink]] on the page into html
+links. The function is passed named parameters "page", "destpage", and
+"content". It should return the linkified content.
+
+Plugins that implement linkify must also implement a scan hook, that scans
+for the links on the page and adds them to `%links`.
+
+### scan
+
+ hook(type => "scan", id => "foo", call => \&scan);
+
+This hook is called early in the process of building the wiki, and is used
+as a first pass scan of the page, to collect metadata about the page. It's
+mostly used to scan the page for WikiLinks, and add them to `%links`.
+
+The function is passed named parameters "page" and "content". Its return
+value is ignored.
### htmlize
hook(type => "pagetemplate", id => "foo", call => \&pagetemplate);
-[[Templates]] are filled out for many different things in ikiwiki, like
-generating a page, or part of a blog page, or an rss feed, or a cgi. This
-hook allows modifying those templates. The function is passed named
-parameters. The "page" and "destpage" parameters are the same as for a
-preprocess hook. The "template" parameter is a [[cpan HTML::Template]]
-object that is the template that will be used to generate the page. The
-function can manipulate that template object.
+[[Templates|wikitemplates]] are filled out for many different things in
+ikiwiki, like generating a page, or part of a blog page, or an rss feed, or
+a cgi. This hook allows modifying the variables available on those
+templates. The function is passed named parameters. The "page" and
+"destpage" parameters are the same as for a preprocess hook. The "template"
+parameter is a [[cpan HTML::Template]] object that is the template that
+will be used to generate the page. The function can manipulate that
+template object.
The most common thing to do is probably to call `$template->param()` to add
a new custom parameter to the template.
+### templatefile
+
+ hook(type => "templatefile", id => "foo", call => \&templatefile);
+
+This hook allows plugins to change the [[template|wikitemplates]] that is
+used for a page in the wiki. The hook is passed a "page" parameter, and
+should return the name of the template file to use, or undef if it doesn't
+want to change the default ("page.tmpl"). Template files are looked for in
+/usr/share/ikiwiki/templates by default.
+
### sanitize
hook(type => "sanitize", id => "foo", call => \&sanitize);
Use this to hook into ikiwiki's cgi script. Each registered cgi hook is
called in turn, and passed a CGI object. The hook should examine the
-parameters, and if it will handle this CGI request, output a page (including the http headers) and
-terminate the program.
+parameters, and if it will handle this CGI request, output a page
+(including the http headers) and terminate the program.
+
+Note that cgi hooks are called as early as possible, before any ikiwiki
+state is loaded, and with no session information.
### auth
if the name is set to the name of a user who is not registered,
a basic registration of the user will be automatically performed.
+### sessioncgi
+
+ hook(type => "sessioncgi", id => "foo", call => \&sessioncgi);
+
+Unlike the cgi hook, which is run as soon as possible, the sessioncgi hook
+is only run once a session object is available. It is passed both a CGI
+object and a session object. To check if the user is in fact signed in, you
+can check if the session object has a "name" parameter set.
+
### canedit
hook(type => "canedit", id => "foo", call => \&pagelocked);
bypass it). When a page is edited, each registered canedit hook is called
in turn, and passed the page name, a CGI object, and a session object.
-If edit can proceed, the hook should return "". If the edit is not allowed
-by this hook, the hook should return an error message for the user to see.
If the hook has no opinion about whether the edit can proceed, return
-`undef`, and the next plugin will be asked to decide.
+`undef`, and the next plugin will be asked to decide. If edit can proceed,
+the hook should return "". If the edit is not allowed by this hook, the
+hook should return an error message for the user to see, or a function
+that can be run to log the user in or perform other action necessary for
+them to be able to edit the page.
+
+This hook should avoid directly redirecting the user to a signin page,
+since it's sometimes used to test to see which pages in a set of pages a
+user can edit.
+
+### editcontent
+
+ hook(type => "editcontent", id => "foo", call => \&editcontent);
+
+This hook is called when a page is saved (or previewed) using the web
+interface. It is passed named parameters: `content`, `page`, `cgi`, and
+`session`. These are, respectively, the new page content as entered by the
+user, the page name, a `CGI` object, and the user's `CGI::Session`.
+
+It can modify the content as desired, and should return the content.
### formbuilder
These hooks allow tapping into the parts of ikiwiki that use [[cpan
CGI::FormBuilder]] to generate web forms. These hooks are passed named
-parameters: `cgi`, `session`, and `form`. These are, respectively, the
-`CGI` object, the user's `CGI::Session`, and a `CGI::FormBuilder`.
+parameters: `cgi`, `session`, `form`, and `buttons`. These are, respectively,
+the `CGI` object, the user's `CGI::Session`, a `CGI::FormBuilder`, and a
+reference to an array of names of buttons to go on the form.
Each time a form is set up, the `formbuilder_setup` hook is called.
Typically the `formbuilder_setup` hook will check the form's title, and if
add/remove/change fields, tweak the validation code for the fields, etc. It
will not validate or display the form.
-Form validation and display can be overridden by the formbuilder hook.
-By default, ikiwiki will do a basic validation and display of the form,
-but if this hook is registered, it will stop that and let the hook take
-over. This hook is passed an additional named parameter: `buttons` is an
-array of the submit buttons for the form.
+Just before a form is displayed to the user, the `formbuilder` hook is
+called. It can be used to validate the form, but should not display it.
### savestate
and a special effort will be made to avoid changing them in incompatible
ways, and to document any changes that have to be made in the future.
-Note that IkiWiki also provides other variables functions that are not
+Note that IkiWiki also provides other variables and functions that are not
exported by default. No guarantee is made about these in the future, so if
it's not exported, the wise choice is to not use it.
hash. The best way to understand the contents of the hash is to look at
[[ikiwiki.setup]], which sets the hash content to configure the wiki.
+### %pagestate
+
+The `%pagestate` hash can be used by plugins to save state that they will need
+next time ikiwiki is run. The hash holds per-page state, so to set a value,
+use `%pagestate{$page}{$id}{$key}=$value`, and to retrieve the value,
+use `%pagestate{$page}{$id}{$key}`.
+
+`$key` can be any string you like, but `$id` must be the same as the "id"
+parameter passed to `hook()` when registering the plugin. This is so
+ikiwiki can know when to delete pagestate for plugins that are no longer
+used.
+
+When pages are deleted, ikiwiki automatically deletes their pagestate too.
+
+Note that page state does not persist across wiki rebuilds, only across
+wiki updates.
+
### Other variables
If your plugin needs to access data about other pages in the wiki. It can
use the following hashes, using a page name as the key:
-* `links` lists the names of each page that a page links to, in an array
+* `%links` lists the names of each page that a page links to, in an array
reference.
* `%destsources` contains the name of the source file used to create each
destination file.
Note that while any plugin can use this for a fatal error, plugins should
try to avoid dying on bad input, as that will halt the entire wiki build
-and make the wiki unusable. So for example, if a [[PreProcessorDirective]]
-is passed bad parameters, it's better to return an error message, which can
-appear on the wiki page, rather than calling error().
+and make the wiki unusable. So for example, if a
+[[ikiwiki/PreProcessorDirective]] is passed bad parameters, it's better to
+return an error message, which can appear on the wiki page, rather than
+calling error().
#### `template($;@)`
#### `add_depends($$)`
-Makes the specified page depend on the specified [[PageSpec]].
+Makes the specified page depend on the specified [[ikiwiki/PageSpec]].
#### `pagespec_match($$;@)`
-Passed a page name, and [[PageSpec]], returns true if the [[PageSpec]]
-matches the page.
+Passed a page name, and [[ikiwiki/PageSpec]], returns true if the
+[[ikiwiki/PageSpec]] matches the page.
Additional named parameters can be passed, to further limit the match.
The most often used is "location", which specifies the location the
existing page that link best points to. Prefers pages under a
subdirectory with the same name as the source page, failing that
goes down the directory tree to the base looking for matching
-pages, as described in [[SubPage/LinkingRules]].
+pages, as described in [[ikiwiki/SubPage/LinkingRules]].
#### `htmllink($$$;@)`
* forcesubpage - set to force a link to a subpage
* linktext - set to force the link text to something
* anchor - set to make the link include an anchor
+* rel - set to add a rel attribute to the link
+* class - set to add a css class to the link
#### `readfile($;$)`
Given a page name and a destination file name (not including the base
destination directory), register that the page will result in that file
-being rendered. It's important to call this before writing to any file in
-the destination directory.
+being rendered.
+
+It's important to call this before writing to any file in the destination
+directory, and it's important to call it consistently every time, even if
+the file isn't really written this time -- unless you delete any old
+version of the file. In particular, in preview mode, this should still be
+called even if the file isn't going to be written to during the preview.
+
+Ikiwiki uses this information to automatically clean up rendered files when
+the page that rendered them goes away or is changes to no longer render
+them. will_render also does a few important security checks.
#### `pagetype($)`
#### `srcfile($)`
Given the name of a source file in the wiki, searches for the file in
-the source directory and the underlay directory, and returns the full
-path to the first file found.
+the source directory and the underlay directories (most recently added
+underlays first), and returns the full path to the first file found.
+
+#### `add_underlay($)`
+
+Adds a directory to the set of underlay directories that ikiwiki will
+search for files.
-#### `displaytime($)`
+If the directory name is not absolute, ikiwiki will assume it is in
+the parent directory of the configured underlaydir.
+
+#### `displaytime($;$)`
Given a time, formats it for display.
+The optional second parameter is a strftime format to use to format the
+time.
+
#### `gettext`
This is the standard gettext function, although slightly optimised.
#### `urlto($$)`
-Construct a relative url to the first parameter from the second.
+Construct a relative url to the first parameter from the page named by the
+second. The first parameter can be either a page name, or some other
+destination file, as registered by `will_render`.
#### `targetpage($$)`
Passed a page and an extension, returns the filename that page will be
rendered to.
+## Internal use pages
+
+Sometimes it's useful to put pages in the wiki without the overhead of
+having them be rendered to individual html files. Such internal use pages
+are collected together to form the RecentChanges page, for example.
+
+To make an internal use page, register a filename extension that starts
+with "_". Internal use pages cannot be edited with the web interface,
+generally shouldn't contain wikilinks or preprocessor directives (use
+either on them with extreme caution), and are not matched by regular
+PageSpecs glob patterns, but instead only by a special `internal()`
+[[ikiwiki/PageSpec]].
+
## RCS plugins
-ikiwiki's support for revision control systems also uses pluggable perl
-modules. These are in the `IkiWiki::RCS` namespace, for example
+ikiwiki's support for [[revision_control_systems|rcs]] also uses pluggable
+perl modules. These are in the `IkiWiki::RCS` namespace, for example
`IkiWiki::RCS::svn`.
Each RCS plugin must support all the `IkiWiki::rcs_*` functions.
See IkiWiki::RCS::Stub for the full list of functions. It's ok if
`rcs_getctime` does nothing except for throwing an error.
-See [[about_RCS_backends]] for some more info.
+See [[RCS_details|rcs/details]] for some more info.
## PageSpec plugins
It's also possible to write plugins that add new functions to
-[[PageSpecs|PageSpec]]. Such a plugin should add a function to the
+[[PageSpecs|ikiwiki/PageSpec]]. Such a plugin should add a function to the
IkiWiki::PageSpec package, that is named `match_foo`, where "foo()" is
-how it will be accessed in a [[PageSpec]]. The function will be passed
+how it will be accessed in a [[ikiwiki/PageSpec]]. The function will be passed
two parameters: The name of the page being matched, and the thing to match
against. It may also be passed additional, named parameters. It should return
a IkiWiki::SuccessReason object if the match succeeds, or an