X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/ec5ddd9a4ffdf3aba86d1302a010819d88c1f456..b09a73db1376f84f80fc1dbd3a892f640fe5eb03:/doc/plugins/write.mdwn?ds=sidebyside diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn index c4f668373..4c66e51f8 100644 --- a/doc/plugins/write.mdwn +++ b/doc/plugins/write.mdwn @@ -1,73 +1,1384 @@ -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]]. -## Note +[[!template id="note" text=""" +Ikiwiki is a compiler One thing to keep in mind when writing a plugin is that ikiwiki is a wiki *compiler*. So plugins influence pages when they are built, not when they are loaded. A plugin that inserts the current time into a page, for -example, will insert the build time. Also, as a compiler, ikiwiki avoids -rebuilding pages unless they have changed, so a plugin that prints some -random or changing thing on a page will generate a static page that won't -change until ikiwiki rebuilds the page for some other reason, like the page -being edited. +example, will insert the build time. + +Also, as a compiler, ikiwiki avoids rebuilding pages unless they have +changed, so a plugin that prints some random or changing thing on a page +will generate a static page that won't change until ikiwiki rebuilds the +page for some other reason, like the page being edited. + +The [[tutorial]] has some other examples of ways that ikiwiki being a +compiler may trip up the unwary. +"""]] + +[[!toc levels=2]] + +## Highlevel view of ikiwiki + +Ikiwiki mostly has two modes of operation. It can either be running +as a compiler, building or updating a wiki; or as a cgi program, providing +user interface for editing pages, etc. Almost everything ikiwiki does +is accomplished by calling various hooks provided by plugins. + +### compiler + +As a compiler, ikiwiki starts by calling the `refresh` hook. Then it checks +the wiki's source to find new or changed pages. The `needsbuild` hook is +then called to allow manipulation of the list of pages that need to be +built. + +Now that it knows what pages it needs to build, ikiwiki runs two +compile passes. First, it runs `scan` hooks, which collect metadata about +the pages. Then it runs a page rendering pipeline, by calling in turn these +hooks: `filter`, `preprocess`, `linkify`, `htmlize`, `indexhtml`, +`pagetemplate`, `sanitize`, `format`. + +After all necessary pages are built, it calls the `change` hook. Finally, +if a page is was deleted, the `delete` hook is called, and the files that +page had previously produced are removed. + +### cgi + +The flow between hooks when ikiwiki is run as a cgi is best illustrated by +an example. + +Alice browses to a page and clicks Edit. + +* Ikiwiki is run as a cgi. It assigns Alice a session cookie, and, + by calling the `auth` hooks, sees that she is not yet logged in. +* The `sessioncgi` hooks are then called, and one of them, + from the [[editpage]] plugin, notices that the cgi has been told "do=edit". +* The [[editpage]] plugin calls the `canedit` hook to check if this + page edit is allowed. The [[signinedit]] plugin has a hook that says not: + Alice is not signed in. +* The [[signinedit]] plugin then launches the signin process. A signin + page is built by calling the `formbuilder_setup` hook. + +Alice signs in with her openid. + +* The [[openid]] plugin's `formbuilder` hook sees that an openid was + entered in the signin form, and redirects to Alice's openid provider. +* Alice's openid provider calls back to ikiwiki. The [[openid]] plugin + has an `auth` hook that finishes the openid signin process. +* Signin complete, ikiwiki returns to what Alice was doing before; editing + a page. +* Now all the `canedit` hooks are happy. The [[editpage]] plugin calls + `formbuilder_setup` to display the page editing form. + +Alice saves her change to the page. + +* The [[editpage]] plugin's `formbuilder` hook sees that the Save button + was pressed, and calls the `checkcontent` and `editcontent` hooks. + Then it saves the page to disk, and branches into the compiler part + of ikiwiki to refresh the wiki. + +## 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 3.00`. + +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. + +## Plugin interface + +To import the ikiwiki plugin interface: + + use IkiWiki '3.00'; + +This will import several variables and functions into your plugin's +namespace. These variables and functions are the ones most plugins need, +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 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. ## Registering plugins -Plugins should, when imported, call IkiWiki::register_plugin to hook into -ikiwiki. The function takes four parameters: +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. 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" parameter, which should be a unique string for this +plugin, and 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, and an optional "first" parameter makes +it run first. Useful if the hook depends on some other hook being run first. + +## Types of hooks + +In roughly the order they are called. + +### getopt + + hook(type => "getopt", id => "foo", call => \&getopt); + +This allows for plugins to perform their own processing of command-line +options and so add options to the ikiwiki command line. It's called during +command line processing, with `@ARGV` full of any options that ikiwiki was +not able to process on its own. The function should process any options it +can, removing them from `@ARGV`, and probably recording the configuration +settings in `%config`. It should take care not to abort if it sees +an option it cannot process, and should just skip over those options and +leave them in `@ARGV`. + +### checkconfig + + hook(type => "checkconfig", id => "foo", call => \&checkconfig); + +This is useful if the plugin needs to check for or modify ikiwiki's +configuration. It's called early in the startup process. `%config` +is populated at this point, but other state has not yet been loaded. +The 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 to observe or even manipulate the list of files that +need to be built when the wiki is refreshed. + +As its first parameter, the function is passed a reference to an array of +files that will be built. It should return an array reference that is a +modified version of its input. It can add or remove files from it. + +The second parameter passed to the function is a reference to an array of +files that have been deleted. + +### 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|ikiwiki/WikiLink]], and add +them to `%links`. Present in IkiWiki 2.40 and later. + +The function is passed named parameters "page" and "content". Its return +value is ignored. + +### filter + + hook(type => "filter", id => "foo", call => \&filter); + +Runs on the full raw source of a page, before anything else touches it, and +can make arbitrary changes. The function is passed named parameters "page", +"destpage", and "content". It should return the filtered content. + +### preprocess + +Adding a preprocessor [[ikiwiki/directive]] is probably the most common use +of a plugin. + + hook(type => "preprocess", id => "foo", call => \&preprocess); + +Replace "foo" with the command name that will be used for the preprocessor +directive. + +Each time the directive is processed, the referenced function (`preprocess` +in the example above) is called. Whatever the function returns goes onto +the page in place of the directive. Or, if the function aborts using +`error()`, the directive will be replaced with the error message. + +The function is passed named parameters. First come the parameters set +in the preprocessor directive. These are passed in the same order as +they're in the directive, and if the preprocessor directive contains a bare +parameter (example: `\[[!foo param]]`), that parameter will be passed with +an empty value. + +After the parameters from the preprocessor directive some additional ones +are passed: A "page" parameter gives the name of the page that embedded the +preprocessor directive, while a "destpage" parameter gives the name of the +page the content is going to (different for inlined pages), and a "preview" +parameter is set to a true value if the page is being previewed. + +If `hook` is passed an optional "scan" parameter, set to a true value, this +makes the hook be called during the preliminary scan that ikiwiki makes of +updated pages, before begining to render pages. This should be done if the +hook modifies data in `%links` (typically by calling `add_link`). Note that +doing so will make the hook 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 context, you can assume it's being run in scan mode, and +avoid doing expensive things at that point.) + +Note that if the [[htmlscrubber]] is enabled, html in +preprocessor [[ikiwiki/directive]] 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|ikiwiki/WikiLink]] on the page into html +links. The function is passed named parameters "page", "destpage", and +"content". It should return the linkified content. Present in IkiWiki 2.40 +and later. + +Plugins that implement linkify must also implement a scan hook, that scans +for the links on the page and adds them to `%links` (typically by calling +`add_link`). + +### htmlize + + hook(type => "htmlize", id => "ext", call => \&htmlize); + +Runs on the source of a page and turns it into html. The id parameter +specifies the filename extension that a file must have to be htmlized using +this plugin. This is how you can add support for new and exciting markup +languages to ikiwiki. + +The function is passed named parameters: "page" and "content" and should +return the htmlized content. + +If `hook` is passed an optional "keepextension" parameter, set to a true +value, then the extension will not be stripped from the source filename when +generating the page. + +If `hook` is passed an optional "noextension" parameter, set to a true +value, then the id parameter specifies not a filename extension, but +a whole filename that can be htmlized. This is useful for files +like `Makefile` that have no extension. + +If `hook` is passed an optional "longname" parameter, this value is used +when prompting a user to choose a page type on the edit page form. + +### indexhtml + + hook(type => "indexhtml", id => "foo", call => \&indexhtml); + +This hook is called once the page has been converted to html (but before +the generated html is put in a template). The most common use is to +update search indexes. Added in ikiwiki 2.54. + +The function is passed named parameters "page", "destpage", and "content". +Its return value is ignored. + +### pagetemplate + + 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 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|templates]] 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 (relative to the +template directory), or undef if it doesn't want to change the default +("page.tmpl"). + +### pageactions + + hook(type => "pageactions", id => "foo", call => \&pageactions); + +This hook allows plugins to add arbitrary actions to the action bar on a +page (next to Edit, RecentChanges, etc). The hook is passed a "page" +parameter, and can return a list of html fragments to add to the action +bar. + +### sanitize + + hook(type => "sanitize", id => "foo", call => \&sanitize); + +Use this to implement html sanitization or anything else that needs to +modify the body of a page after it has been fully converted to html. + +The function is passed named parameters: "page", "destpage", and "content", +and should return the sanitized content. + +### format + + hook(type => "format", id => "foo", call => \&format); + +The difference between format and sanitize is that sanitize only acts on +the page body, while format can modify the entire html page including the +header and footer inserted by ikiwiki, the html document type, etc. (It +should not rely on always being passed the entire page, as it won't be +when the page is being previewed.) + +The function is passed named parameters: "page" and "content", and +should return the formatted content. + +### build_affected + + hook(type => "build_affected", id => "foo", call => \&build_affected); + +This hook is called after the directly changed pages have been built, +and can cause extra pages to be built. If links and backlinks were provided +by a plugin, this would be where that plugin would rebuild pages whose +backlinks have changed, for instance. The [[trail]] plugin uses this hook +to rebuild pages whose next or previous page has changed. + +The function should currently ignore its parameters. It returns a list with +an even number of items (a hash in list context), where the first item of +each pair is a page name to be rebuilt (if it was not already rebuilt), and +the second is a log message resembling +`building plugins/write because the phase of the moon has changed`. + +### delete + + hook(type => "delete", id => "foo", call => \&delete); + +After a page or pages is removed from the wiki, the referenced function +is called, and passed the names of the source files that were removed. + +### rendered + + hook(type => "rendered", id => "foo", call => \&rendered); + +After ikiwiki renders a change or addition (but not deletion) to the +wiki, the referenced function is called, and passed the names of the +source files that were rendered. + +(This hook used to be called "change", but that was not accurate. +For now, plugins using the old hook name will still work.) + +### changes + + hook(type => "changes", id => "foo", call => \&changes); + +After ikiwiki renders changes to the wiki, the referenced function is +called, and passed the names of the source files that were added, modified, +or deleted. + +### cgi + + hook(type => "cgi", id => "foo", call => \&cgi); + +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. + +Note that cgi hooks are called as early as possible, before any ikiwiki +state is loaded, and with no session information. + +### auth + + hook(type => "auth", id => "foo", call => \&auth); + +This hook can be used to implement an authentication method. When a user +needs to be authenticated, each registered auth hook is called in turn, and +passed a CGI object and a session object. + +If the hook is able to authenticate the user, it should set the session +object's "name" parameter to the authenticated user's name. Note that +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 => \&canedit); + +This hook can be used to implement arbitrary access methods to control when +a page can be edited using the web interface (commits from revision control +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 the hook has no opinion about whether the edit can proceed, return +`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. + +### canremove + + hook(type => "canremove", id => "foo", call => \&canremove); + +This hook can be used to implement arbitrary access methods to control +when a page can be removed using the web interface (commits from +revision control bypass it). It works exactly like the `canedit` hook, +but is passed the named parameters `cgi` (a CGI object), `session` +(a session object) and `page` (the page subject to deletion). + +### canrename + + hook(type => "canrename", id => "foo", call => \&canrename); + +This hook can be used to implement arbitrary access methods to control when +a page can be renamed using the web interface (commits from revision control +bypass it). It works exactly like the `canedit` hook, +but is passed the named parameters `cgi` (a CGI object), `session` (a +session object), `src`, `srcfile`, `dest` and `destfile`. + +### checkcontent + + hook(type => "checkcontent", id => "foo", call => \&checkcontent); + +This hook is called to check the content a user has entered on a page, +before it is saved, and decide if it should be allowed. + +It is passed named parameters: `content`, `page`, `cgi`, and `session`. If +the content the user has entered is a comment, it may also be passed some +additional parameters: `author`, `url`, and `subject`. The `subject` +parameter may also be filled with the user's comment about the change. + +Note: When the user edits an existing wiki page, this hook is also +passed a `diff` named parameter, which will include only the lines +that they added to the page, or modified. + +The hook should return `undef` on success. If the content is disallowed, it +should return a message stating what the problem is, or a function +that can be run to perform whatever action is necessary to allow the user +to post the content. + +### 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 + + hook(type => "formbuilder_setup", id => "foo", call => \&formbuilder_setup); + hook(type => "formbuilder", id => "foo", call => \&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`, `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 +it's a form that it needs to modify, will call various methods to +add/remove/change fields, tweak the validation code for the fields, etc. It +will not validate or display 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 + + hook(type => "savestate", id => "foo", call => \&savestate); + +This hook is called whenever ikiwiki normally saves its state, just before +the state is saved. The function can save other state, modify values before +they're saved, etc. + +### renamepage + + hook(type => "renamepage", id => "foo", call => \&renamepage); + +This hook is called by the [[plugins/rename]] plugin when it renames +something, once per page linking to the renamed page's old location. +The hook is passed named parameters: `page`, `oldpage`, `newpage`, and +`content`, and should try to modify the content of `page` to reflect +the name change. For example, by converting links to point to the +new page. + +### rename + + hook(type => "rename", id => "foo", call => \&rename); + +When a page or set of pages is renamed, the referenced function is +called for every page, and is passed named parameters: + +* `torename`: a reference to a hash with keys: `src`, `srcfile`, + `dest`, `destfile`, `required`. +* `cgi`: a CGI object +* `session`: a session object. + +Such a hook function returns any additional rename hashes it wants to +add. This hook is applied recursively to returned additional rename +hashes, so that it handles the case where two plugins use the hook: +plugin A would see when plugin B adds a new file to be renamed. + +### getsetup + + hook(type => "getsetup", id => "foo", call => \&getsetup); + +This hooks is not called during normal operation, but only when setting up +the wiki, or generating a setup file. Plugins can use this hook to add +configuration options. + +The hook is passed no parameters. It returns data about the configuration +options added by the plugin. It can also check if the plugin is usable, and +die if not, which will cause the plugin to not be offered in the configuration +interface. + +The data returned is a list of `%config` options, followed by a hash +describing the option. There can also be an item named "plugin", which +describes the plugin as a whole. For example: + + return + plugin => { + description => "description of this plugin", + safe => 1, + rebuild => 1, + section => "misc", + }, + option_foo => { + type => "boolean", + description => "enable foo?", + advanced => 1, + safe => 1, + rebuild => 1, + }, + option_bar => { + type => "string", + example => "hello", + description => "option bar", + safe => 1, + rebuild => 0, + }, + +* `type` can be "boolean", "string", "integer", "pagespec", + or "internal" (used for values that are not user-visible). The type is + the type of the leaf values; the `%config` option may be an array or + hash of these. +* `example` can be set to an example value. +* `description` is a short description of the option. +* `link` is a link to further information about the option. This can either + be a [[ikiwiki/WikiLink]], or an url. +* `htmldescription` is displayed instead of the description by websetup. +* `advanced` can be set to true if the option is more suitable for advanced + users. +* `safe` should be false if the option should not be displayed in unsafe + configuration methods, such as the web interface. Anything that specifies + a command to run, a path on disk, or a regexp should be marked as unsafe. + If a plugin is marked as unsafe, that prevents it from being + enabled/disabled. +* `rebuild` should be true if changing the option (or enabling/disabling + the plugin) will require a wiki rebuild, false if no rebuild is needed, + and undef if a rebuild could be needed in some circumstances, but is not + strictly required. +* `section` can optionally specify which section in the config file + the plugin fits in. The convention is to name the sections the + same as the tags used for [[plugins|plugin]] on this wiki. + +### genwrapper + + hook(type => "genwrapper", id => "foo", call => \&genwrapper); + +This hook is used to inject C code (which it returns) into the `main` +function of the ikiwiki wrapper when it is being generated. + +The code runs before anything else -- in particular it runs before +the suid wrapper has sanitized its environment. + +### disable + + hook(type => "disable", id => "foo", call => \&disable); + +This hook is only run when a previously enabled plugin gets disabled +during ikiwiki setup. Plugins can use this to perform cleanups. + +## Exported variables + +Several variables are exported to your plugin when you `use IkiWiki;` + +### `%config` + +A plugin can access the wiki's configuration via the `%config` +hash. The best way to understand the contents of the hash is to look at +your ikiwiki setup file, 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}`. + +The `$value` can be anything that perl's Storable module is capable of +serializing. `$key` can be any string you like, but `$id` must be the same +as the "id" parameter passed to `hook()` when registering the plugin. This +is so ikiwiki can know when to delete pagestate for plugins that are no +longer used. + +When pages are deleted, ikiwiki automatically deletes their pagestate too. + +Note that page state does not persist across wiki rebuilds, only across +wiki updates. + +### `%wikistate` + +The `%wikistate` hash can be used by a plugin to store persistant state +that is not bound to any one page. To set a value, use +`$wikistate{$id}{$key}=$value, where `$value` is anything Storable can +serialize, `$key` is any string you like, and `$id` must be the same as the +"id" parameter passed to `hook()` when registering the plugin, so that the +state can be dropped if the plugin is no longer used. + +### `%links` + +The `%links` hash can be used to look up the names of each page that +a page links to. The name of the page is the key; the value is an array +reference. Do not modify this hash directly; call `add_link()`. + + $links{"foo"} = ["bar", "baz"]; + +### `%typedlinks` + +The `%typedlinks` hash records links of specific types. Do not modify this +hash directly; call `add_link()`. The keys are page names, and the values +are hash references. In each page's hash reference, the keys are link types +defined by plugins, and the values are hash references with link targets +as keys, and 1 as a dummy value, something like this: + + $typedlinks{"foo"} = { + tag => { short_word => 1, metasyntactic_variable => 1 }, + next_page => { bar => 1 }, + }; + +Ordinary [[WikiLinks|ikiwiki/WikiLink]] appear in `%links`, but not in +`%typedlinks`. + +### `%pagesources` + +The `%pagesources` has can be used to look up the source filename +of a page. So the key is the page name, and the value is the source +filename. Do not modify this hash. + + $pagesources{"foo"} = "foo.mdwn"; + +### `%destsources` + +The `%destsources` hash records the name of the source file used to +create each destination file. The key is the output filename (ie, +"foo/index.html"), and the value is the source filename that it was built +from (eg, "foo.mdwn"). Note that a single source file may create multiple +destination files. Do not modify this hash directly; call `will_render()`. + + $destsources{"foo/index.html"} = "foo.mdwn"; + +## Library functions + +Several functions are exported to your plugin when you `use IkiWiki;` + +### `hook(@)` + +Hook into ikiwiki's processing. See the discussion of hooks above. + +Note that in addition to the named parameters described above, a parameter +named `no_override` is supported, If it's set to a true value, then this hook +will not override any existing hook with the same id. This is useful if +the id can be controled by the user. + +### `debug($)` + +Logs a debugging message. These are supressed unless verbose mode is turned +on. + +### `error($;$)` + +Aborts with an error message. If the second parameter is passed, it is a +function that is called after the error message is printed, to do any final +cleanup. + +If called inside a preprocess hook, error() does not abort the entire +wiki build, but instead replaces the preprocessor [[ikiwiki/directive]] with +a version containing the error message. + +In other hooks, error() is a fatal error, so use with care. Try to avoid +dying on bad input when building a page, as that will halt +the entire wiki build and make the wiki unusable. + +### `template($;@)` + +Creates and returns a [[!cpan HTML::Template]] object. (In a list context, +returns the parameters needed to construct the obhect.) + +The first parameter is the name of the template file. The optional remaining +parameters are passed to `HTML::Template->new`. + +Normally, the template file is first looked for in the templates/ subdirectory +of the srcdir. Failing that, it is looked for in the templatedir. + +Wiki pages can be used as templates. This should be done only for templates +which it is safe to let wiki users edit. Enable it by passing a filename +with no ".tmpl" extension. Template pages are normally looked for in +the templates/ directory. If the page name starts with "/", a page +elsewhere in the wiki can be used. + +If the template is not found, or contains a syntax error, an error is thrown. + +### `template_depends($$;@)` + +Use this instead of `template()` if the content of a template is being +included into a page. This causes the page to depend on the template, +so it will be updated if the template is modified. + +Like `template()`, except the second parameter is the page. + +### `htmlpage($)` + +Passed a page name, returns the base name that will be used for a the html +page created from it. (Ie, it appends ".html".) + +Use this when constructing the filename of a html file. Use `urlto` when +generating a link to a page. + +### `pagespec_match_list($$;@)` + +Passed a page name, and [[ikiwiki/PageSpec]], returns a list of pages +in the wiki that match the [[ikiwiki/PageSpec]]. + +The page will automatically be made to depend on the specified +[[ikiwiki/PageSpec]], so `add_depends` does not need to be called. This +is often significantly more efficient than calling `add_depends` and +`pagespec_match` in a loop. You should use this anytime a plugin +needs to match a set of pages and do something based on that list. + +Unlike pagespec_match, this may throw an error if there is an error in +the pagespec. + +Additional named parameters can be specified: + +* `deptype` optionally specifies the type of dependency to add. Use the + `deptype` function to generate a dependency type. +* `filter` is a reference to a function, that is called and passed a page, + and returns true if the page should be filtered out of the list. +* `sort` specifies a sort order for the list. See + [[ikiwiki/PageSpec/sorting]] for the avilable sort methods. Note that + if a sort method is specified that depends on the + page content (such as 'meta(foo)'), the deptype needs to be set to + a content dependency. +* `reverse` if true, sorts in reverse. +* `num` if nonzero, specifies the maximum number of matching pages that + will be returned. +* `list` makes it only match amoung the specified list of pages. + Default is to match amoung all pages in the wiki. + +Any other named parameters are passed on to `pagespec_match`, to further +limit the match. + +### `add_depends($$;$)` + +Makes the specified page depend on the specified [[ikiwiki/PageSpec]]. + +By default, dependencies are full content dependencies, meaning that the +page will be updated whenever anything matching the PageSpec is modified. +This can be overridden by passing a `deptype` value as the third parameter. + +### `pagespec_match($$;@)` + +Passed a page name, and [[ikiwiki/PageSpec]], returns a true value if the +[[ikiwiki/PageSpec]] matches the page. + +Note that the return value is overloaded. If stringified, it will be a +message indicating why the PageSpec succeeded, or failed, to match the +page. + +Additional named parameters can be passed, to further limit the match. +The most often used is "location", which specifies the location the +PageSpec should match against. If not passed, relative PageSpecs will match +relative to the top of the wiki. + +### `deptype(@)` + +Use this function to generate ikiwiki's internal representation of a +dependency type from one or more of these keywords: + +* `content` is the default. Any change to the content + of a page triggers the dependency. +* `presence` is only triggered by a change to the presence + of a page. +* `links` is only triggered by a change to the links of a page. + This includes when a link is added, removed, or changes what + it points to due to other changes. It does not include the + addition or removal of a duplicate link. + +If multiple types are specified, they are combined. + +### `bestlink($$)` + +Given a page and the text of a link on the page, determine which +existing page that link best points to. Prefers pages under a +subdirectory with the same name as the source page, failing that +goes down the directory tree to the base looking for matching +pages, as described in [[ikiwiki/SubPage/LinkingRules]]. + +### `htmllink($$$;@)` + +Many plugins need to generate html links and add them to a page. This is +done by using the `htmllink` function. The usual way to call +`htmllink` is: + + htmllink($page, $page, $link) + +Why is `$page` repeated? Because if a page is inlined inside another, and a +link is placed on it, the right way to make that link is actually: + + htmllink($page, $destpage, $link) + +Here `$destpage` is the inlining page. A `destpage` parameter is passed to +some of the hook functions above; the ones that are not passed it are not used +during inlining and don't need to worry about this issue. + +After the three required parameters, named parameters can be used to +control some options. These are: + +* noimageinline - set to true to avoid turning links into inline html images +* 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 +* title - set to add a title attribute to the link + +### `readfile($;$)` + +Given a filename, reads and returns the entire file. + +The optional second parameter, if set to a true value, makes the file be read +in binary mode. + +A failure to read the file will result in it dying with an error. + +### `writefile($$$;$$)` + +Given a filename, a directory to put it in, and the file's content, +writes a file. + +The optional fourth parameter, if set to a true value, makes the file be +written in binary mode. + +The optional fifth parameter can be used to pass a function reference that +will be called to handle writing to the file. The function will be called +and passed a file descriptor it should write to, and an error recovery +function it should call if the writing fails. (You will not normally need to +use this interface.) + +A failure to write the file will result in it dying with an error. + +If the destination directory doesn't exist, it will first be created. + +The filename and directory are separate parameters because of +some security checks done to avoid symlink attacks. Before writing a file, +it checks to make sure there's not a symlink with its name, to avoid +following the symlink. If the filename parameter includes a subdirectory +to put the file in, it also checks if that subdirectory is a symlink, etc. +The directory parameter, however, is not checked for symlinks. So, +generally the directory parameter is a trusted toplevel directory like +the srcdir or destdir, and any subdirectories of this are included in the +filename parameter. + +### `will_render($$)` + +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, 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 changed to no longer render +them. will_render also does a few important security checks. + +### `pagetype($)` + +Given the name of a source file, returns the type of page it is, if it's +a type that ikiwiki knowns how to htmlize. Otherwise, returns undef. + +### `pagename($)` + +Given the name of a source file, returns the name of the wiki page +that corresponds to that file. + +### `pagetitle($)` + +Give the name of a wiki page, returns a version suitable to be displayed as +the page's title. This is accomplished by de-escaping escaped characters in +the page name. "_" is replaced with a space, and '__NN__' is replaced by +the UTF character with code NN. + +### `titlepage($)` + +This performs the inverse of `pagetitle`, ie, it converts a page title into +a wiki page name. + +### `linkpage($)` + +This converts text that could have been entered by the user as a +[[ikiwiki/WikiLink]] into a wiki page name. + +### `srcfile($;$)` + +Given the name of a source file in the wiki, searches for the file in +the source directory and the underlay directories (most recently added +underlays first), and returns the full path to the first file found. + +Normally srcfile will fail with an error message if the source file cannot +be found. The second parameter can be set to a true value to make it return +undef instead. + +### `add_underlay($)` + +Adds a directory to the set of underlay directories that ikiwiki will +search for files. + +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. + +If the third parameter is true, this is the publication time of a page. +(Ie, set the html5 pubdate attribute.) + +### `gettext` + +This is the standard gettext function, although slightly optimised. + +### `ngettext` + +This is the standard ngettext function, although slightly optimised. + +### `urlto($;$$)` + +Construct a relative url to the first parameter from the page named by the +second. The first parameter can be either a page name, or some other +destination file, as registered by `will_render`. + +Provide a second parameter whenever possible, since this leads to better +behaviour for the [[plugins/po]] plugin and `file:///` URLs. + +If the second parameter is not specified (or `undef`), the URL will be +valid from any page on the wiki, or from the CGI; if possible it'll +be a path starting with `/`, but an absolute URL will be used if +the wiki and the CGI are on different domains. + +If the third parameter is passed and is true, the url will be a fully +absolute url. This is useful when generating an url to publish elsewhere. + +### `newpagefile($$)` + +This can be called when creating a new page, to determine what filename +to save the page to. It's passed a page name, and its type, and returns +the name of the file to create, relative to the srcdir. + +### `targetpage($$;$)` + +Passed a page and an extension, returns the filename that page will be +rendered to. + +Optionally, a third parameter can be passed, to specify the preferred +filename of the page. For example, `targetpage("foo", "rss", "feed")` +will yield something like `foo/feed.rss`. + +### `add_link($$;$)` + +This adds a link to `%links`, ensuring that duplicate links are not +added. Pass it the page that contains the link, and the link text. + +An optional third parameter sets the link type. If not specified, +it is an ordinary [[ikiwiki/WikiLink]]. + +### `add_autofile($$$)` + +Sometimes you may want to add a file to the `srcdir` as a result of content +of other pages. For example, [[plugins/tag]] pages can be automatically +created as needed. This function can be used to do that. + +The three parameters are the filename to create (relative to the `srcdir`), +the name of the plugin, and a callback function. The callback will be +called if it is appropriate to automatically add the file, and should then +take care of creating it, and doing anything else it needs to (such as +checking it into revision control). Note that the callback may not always +be called. For example, if an automatically added file is deleted by the +user, ikiwiki will avoid re-adding it again. + +This function needs to be called during the scan hook, or earlier in the +build process, in order to add the file early enough for it to be built. + +## Miscellaneous + +### 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|ikiwiki/WikiLink]] 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|rcs]] is also done via +plugins. See [[RCS_details|rcs/details]] for some more info. + +RCS plugins must register a number of hooks. Each hook has type 'rcs', +and the 'id' field is set to the name of the hook. For example: + + hook(type => "rcs", id => "rcs_update", call => \&rcs_update); + hook(type => "rcs", id => "rcs_prepedit", call => \&rcs_prepedit); + +#### `rcs_update()` + +Updates the working directory with any remote changes. + +#### `rcs_prepedit($)` + +Is passed a file to prepare to edit. It can generate and return an arbitrary +token, that will be passed into `rcs_commit` when committing. For example, +it might return the current revision ID of the file, and use that +information later when merging changes. + +#### `rcs_commit(@)` + +Passed named parameters: `file`, `message`, `token` (from `rcs_prepedit`), +and `session` (optional). + +Should try to commit the file. Returns `undef` on *success* and a version +of the page with the rcs's conflict markers on failure. + +#### `rcs_commit_staged(@)` + +Passed named parameters: `message`, and `session` (optional). + +Should commit all staged changes. Returns undef on success, and an +error message on failure. + +Changes can be staged by calls to `rcs_add`, `rcs_remove`, and +`rcs_rename`. + +#### `rcs_add($)` + +Adds the passed file to the archive. The filename is relative to the root +of the srcdir. + +Note that this should not commit the new file, it should only +prepare for it to be committed when rcs_commit (or `rcs_commit_staged`) is +called. Note that the file may be in a new subdir that is not yet in +to version control; the subdir can be added if so. + +#### `rcs_remove($)` + +Remove a file. The filename is relative to the root of the srcdir. + +Note that this should not commit the removal, it should only prepare for it +to be committed when `rcs_commit` (or `rcs_commit_staged`) is called. + +#### `rcs_rename($$)` + +Rename a file. The filenames are relative to the root of the srcdir. + +Note that this should not commit the rename, it should only +prepare it for when `rcs_commit` (or `rcs_commit_staged`) is called. +The new filename may be in a new subdir, that is not yet added to +version control. If so, the subdir will exist already, and should +be added to revision control. + +#### `rcs_recentchanges($)` + +Examine the RCS history and generate a list of recent changes. +The parameter is how many changes to return. + +The data structure returned for each change is: + + { + rev => # the RCSs id for this commit + user => # user who made the change (may be an openid), + nickname => # short name for user (optional; not an openid), + + committype => # either "web" or the name of the rcs, + when => # time when the change was made, + message => [ + { line => "commit message line 1" }, + { line => "commit message line 2" }, + # etc, + ], + pages => [ + { + page => # name of page changed, + diffurl => # optional url to a diff of changes + }, + # repeat for each page changed in this commit, + ], + } + +#### `rcs_diff($;$)` + +The first parameter is the rev from `rcs_recentchanges`. +The optional second parameter is how many lines to return (default: all). + +Should return a list of lines of the diff (including \n) in list +context, and a string containing the whole diff in scalar context. + +#### `rcs_getctime($)` + +This is used to get the page creation time for a file from the RCS, by looking +it up in the history. + +If the RCS cannot determine a ctime for the file, return 0. + +#### `rcs_getmtime($)` + +This is used to get the page modification time for a file from the RCS, by +looking it up in the history. + +It's ok if this is not implemented, and throws an error. + +If the RCS cannot determine a mtime for the file, return 0. + +#### `rcs_receive()` + +This is called when ikiwiki is running as a pre-receive hook (or +equivalent), and is testing if changes pushed into the RCS from an +untrusted user should be accepted. This is optional, and doesn't make +sense to implement for all RCSs. + +It should examine the incoming changes, and do any sanity +checks that are appropriate for the RCS to limit changes to safe file adds, +removes, and changes. If something bad is found, it should die, to abort +the push. Otherwise, it should return a list of files that were changed, +in the form: + + { + file => # name of file that was changed + action => # either "add", "change", or "remove" + path => # temp file containing the new file content, only + # needed for "add"/"change", and only if the file + # is an attachment, not a page + } + +The list will then be checked to make sure that each change is one that +is allowed to be made via the web interface. + +#### `rcs_preprevert($)` + +This is called by the revert web interface. It is passed a RCS-specific +change ID, and should determine what the effects would be of reverting +that change, and return the same data structure as `rcs_receive`. + +Like `rcs_receive`, it should do whatever sanity checks are appropriate +for the RCS to limit changes to safe changes, and die if a change would +be unsafe to revert. + +#### `rcs_revert($)` + +This is called by the revert web interface. It is passed a named +parameter rev that is the RCS-specific change ID to revert. + +It should try to revert the specified rev, and leave the reversion staged +so `rcs_commit_staged` will complete it. It should return undef on _success_ +and an error message on failure. + +This hook and `rcs_preprevert` are optional, if not implemented, no revert +web interface will be available. + +### PageSpec plugins + +It's also possible to write plugins that add new functions to +[[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 [[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 IkiWiki::FailReason object if the match fails. If the match cannot be +attempted at all, for any page, it can instead return an +IkiWiki::ErrorReason object explaining why. + +When constructing these objects, you should also include information about +of any pages whose contents or other metadata influenced the result of the +match. Do this by passing a list of pages, followed by `deptype` values. + +For example, "backlink(foo)" is influenced by the contents of page foo; +"link(foo)" and "title(bar)" are influenced by the contents of any page +they match; "created_before(foo)" is influenced by the metadata of foo; +while "glob(*)" is not influenced by the contents of any page. + +### Sorting plugins + +Similarly, it's possible to write plugins that add new functions as +[[ikiwiki/pagespec/sorting]] methods. To achieve this, add a function to +the IkiWiki::SortSpec package named `cmp_foo`, which will be used when sorting +by `foo` or `foo(...)` is requested. + +The names of pages to be compared are in the global variables `$a` and `$b` +in the IkiWiki::SortSpec package. The function should return the same thing +as Perl's `cmp` and `<=>` operators: negative if `$a` is less than `$b`, +positive if `$a` is greater, or zero if they are considered equal. It may +also raise an error using `error`, for instance if it needs a parameter but +one isn't provided. + +The function will also be passed one or more parameters. The first is +`undef` if invoked as `foo`, or the parameter `"bar"` if invoked as `foo(bar)`; +it may also be passed additional, named parameters. + +### Setup plugins + +The ikiwiki setup file is loaded using a pluggable mechanism. If you look +at the top of a setup file, it starts with 'use IkiWiki::Setup::Standard', +and the rest of the file is passed to that module's import method. + +It's possible to write other modules in the `IkiWiki::Setup::` namespace that +can be used to configure ikiwiki in different ways. These modules should, +when imported, populate `$IkiWiki::Setup::raw_setup` with a reference +to a hash containing all the config items. They should also implement a +`gendump` function. + +By the way, to parse a ikiwiki setup file and populate `%config`, a +program just needs to do something like: +`use IkiWiki::Setup; IkiWiki::Setup::load($filename)` + +### Function overriding + +Sometimes using ikiwiki's pre-defined hooks is not enough. Your plugin +may need to replace one of ikiwiki's own functions with a modified version, +or wrap one of the functions. + +For example, your plugin might want to override `displaytime`, to change +the html markup used when displaying a date. Or it might want to override +`IkiWiki::formattime`, to change how a date is formatted. Or perhaps you +want to override `bestlink` and change how ikiwiki deals with [[WikiLinks|ikiwiki/WikiLink]]. + +By venturing into this territory, your plugin is becoming tightly tied to +ikiwiki's internals. And it might break if those internals change. But +don't let that stop you, if you're brave. + +Ikiwiki provides an `inject()` function, that is a powerful way to replace +any function with one of your own. This even allows you to inject a +replacement for an exported function, like `bestlink`. Everything that +imports that function will get your version instead. Pass it the name of +the function to replace, and a new function to call. + +For example, here's how to replace `displaytime` with a version using HTML 5 +markup: + + inject(name => 'IkiWiki::displaytime', call => sub { + return ""; + }); + +Here's how to wrap `bestlink` with a version that tries to handle +plural words: + + my $origbestlink=\&bestlink; + inject(name => 'IkiWiki::bestlink', call => \&mybestlink); + + sub deplural ($) { + my $word=shift; + $word =~ s/e?s$//; # just an example :-) + return $word; + } + + sub mybestlink ($$) { + my $page=shift; + my $link=shift; + my $ret=$origbestlink->($page, $link); + if (! length $ret) { + $ret=$origbestlink->($page, deplural($link)); + } + return $ret; + } -1. A method type. Use "preprocess" to register a [[PreProcessorDirective]] -2. A command name. This is the bit that will appear inside brackets in a - page. -3. A reference to a subroutine that is run when the plugin is used. +### Javascript -## Writing a [[PreProcessorDirective]] +Some plugins use javascript to make ikiwiki look a bit more web-2.0-ish. -For preprocessor directives, the subroutine is passed named parameters. A -"page" parameter gives the name of the page that embedded the preprocessor directive. All parameters included in the directive are included -as named parameters as well. Whatever the subroutine returns goes onto the -page in place of the directive. +All javascript code should be put in `.js` files in the `javascript` +underlay, and plugins using those files can enable use of the underlay by +calling `add_underlay("javascript");` in their `import` function. -## Error handing in plugins +You'll have to arrange for `