X-Git-Url: http://git.vanrenterghem.biz/git.ikiwiki.info.git/blobdiff_plain/a0d372751a79bf426ddcde89ada051bf748d8603..376944cb026945ab597db01eb1e3aea4fa320007:/doc/plugins/write.mdwn diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn index 0f2c26344..e1e057c00 100644 --- a/doc/plugins/write.mdwn +++ b/doc/plugins/write.mdwn @@ -1,10 +1,37 @@ -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 +[[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 *compiler*. So plugins influence pages when they are built, not when they @@ -17,57 +44,533 @@ being edited. ## 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. 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 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 +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. 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 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. + +### filter + + hook(type => "filter", id => "foo", call => \&filter); + +Runs on the 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 [[ikiwiki/PreProcessorDirective]] 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 inside brackets for +the preprocessor directive. + +Each time the directive is processed, the referenced function (`preprocess` +in the example above) is called, and is passed named parameters. 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. All +parameters included in the directive are included as named parameters as +well. Whatever the function returns goes onto the page in place of the +directive. + +An optional "scan" parameter, if set to a true value, makes the hook be +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. (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 +[[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. + +### htmlize + + hook(type => "htmlize", id => "ext", call => \&htmlize); + +Runs on the raw 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. + +### pagetemplate + + hook(type => "pagetemplate", id => "foo", call => \&pagetemplate); + +[[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 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" 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. + +The function is passed named parameters: "page" and "content", and +should return the formatted content. + +### delete + + hook(type => "delete", id => "foo", call => \&delete); + +Each time 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. + +### change + + hook(type => "change", id => "foo", call => \&render); + +Each time 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. + +### 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 a different authentication method than +the standard web form. 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 => \&pagelocked); + +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. + +### 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. -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. +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. -## Writing a [[PreProcessorDirective]] +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. -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. +### savestate -## Error handing in plugins + hook(type => "savestate", id => "foo", call => \&savestate); -While a plugin can call ikiwiki's error routine for a fatal error, for -errors that aren't intended to halt the entire wiki build, including bad -parameters passed to a [[PreProcessorDirective]], etc, it's better to just -return the error message as the output of the plugin. +This hook is called wheneven ikiwiki normally saves its state, just before +the state is saved. The function can save other state, modify values before +they're saved, etc. -## Html issues +## Plugin interface -Note that if [[HTMLSanitization]] 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 passed through markdown along with the rest of the page. +To import the ikiwiki plugin interface: -## Wiki configuration + use IkiWiki '1.00'; -A plugin can access the wiki's configuration via the `%IkiWiki::config` hash. -The best way to understand the contents of the hash is to look at +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. + +### %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 [[ikiwiki.setup]], which sets the hash content to configure the wiki. -## Wiki data +### %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: -* `%IkiWiki::links` lists the names of each page - that is linked to from that page in an array reference. -* `%IkiWiki::pagemtime` contains the last modification time of each page -* `%IkiWiki::pagectime` contains the creation time of each page` -* `%IkiWiki::renderedfiles` contains the name of the file rendered by a - page -* `%IkiWiki::pagesources` contains the name of the source file for a page. -* `%IkiWiki::depends` contains a [[GlobList]] that is used to specify other - pages that a page depends on. If one of its dependencies is updated, the - page will also get rebuilt. - - Many plugins will need to add dependencies to this hash; the best way to do - it is by using the IkiWiki::add_depends function, which takes as its - parameters the page name and a [[GlobList]] of dependencies to add. +* `%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. +* `%pagesources` contains the name of the source file for each page. + +Also, the %IkiWiki::version variable contains the version number for the +ikiwiki program. + +### Library functions + +#### `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($)` + +Logs a debugging message. These are supressed unless verbose mode is turned +on. + +#### `error($;$)` + +Aborts with an error message. If the second parameter is passed, it is a +function that is called after the error message is printed, to do any final +cleanup. + +Note that while any plugin can use this for a fatal error, plugins should +try to avoid dying on bad input, as that will halt the entire wiki build +and make the wiki unusable. So for example, if a +[[ikiwiki/PreProcessorDirective]] is passed bad parameters, it's better to +return an error message, which can appear on the wiki page, rather than +calling error(). + +#### `template($;@)` + +Creates and returns a [[cpan HTML::Template]] object. The first parameter +is the name of the file in the template directory. The optional remaining +parameters are passed to `HTML::Template->new`. + +#### `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".) + +#### `add_depends($$)` + +Makes the specified page depend on the specified [[ikiwiki/PageSpec]]. + +#### `pagespec_match($$;@)` + +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 +PageSpec should match against. If not passed, relative PageSpecs will match +relative to the top of the wiki. + +#### `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 +`htmlllink` 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 + +#### `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. + +#### `will_render($$)` + +Given a page name and a destination file name (not including the base +destination directory), register that the page will result in that file +being rendered. + +It's important to call this before writing to any file in the destination +directory, and it's important to call it consistently every time, even if +the file isn't really written this time -- unless you delete any old +version of the file. In particular, in preview mode, this should still be +called even if the file isn't going to be written to during the preview. + +Ikiwiki uses this information to automatically clean up rendered files when +the page that rendered them goes away or is changes to no longer render +them. will_render also does a few important security checks. + +#### `pagetype($)` + +Given the name of a source file, returns the type of page it is, if it's +a type that ikiwiki knowns how to htmlize. Otherwise, returns undef. + +#### `pagename($)` + +Given the name of a source file, returns the name of the wiki page +that corresponds to that file. + +#### `srcfile($)` + +Given the name of a source file in the wiki, searches for the file in +the source directory and the underlay directories (most recently added +underlays first), and returns the full path to the first file found. + +#### `add_underlay($)` + +Adds a directory to the set of underlay directories that ikiwiki will +search for files. + +If the directory name is not absolute, ikiwiki will assume it is in +the parent directory of the configured underlaydir. + +#### `displaytime($;$)` + +Given a time, formats it for display. + +The optional second parameter is a strftime format to use to format the +time. + +#### `gettext` + +This is the standard gettext function, although slightly optimised. + +#### `urlto($$)` + +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`. + +#### `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|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 [[RCS_details|rcs/details]] for some more info. + +## 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.