document writefile symlink checks

[ikiwiki.git] / doc / plugins / write.mdwn

diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index daf70c8e23393d5b860b30e324523da6f46c45ab..1a119b99b679498c5188620a56e9d7fce81c5bc6 100644 (file)
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -19,7 +19,7 @@ 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
 `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`.
+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
 
 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


@@ -55,8 +55,8 @@ 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
 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.
+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
 
 
 ## Types of hooks
 


@@ -196,7 +196,6 @@ generating the page.
 
        hook(type => "pagetemplate", id => "foo", call => \&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|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


@@ -304,7 +303,7 @@ can check if the session object has a "name" parameter set.
 
 ### canedit
 
 
 ### canedit
 

-       hook(type => "canedit", id => "foo", call => \&pagelocked);
+       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
 
 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


@@ -322,6 +321,26 @@ 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.
 
 since it's sometimes used to test to see which pages in a set of pages a
 user can edit.
 

+### 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, the passed `content` 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);
 ### editcontent
 
        hook(type => "editcontent", id => "foo", call => \&editcontent);


@@ -432,7 +451,7 @@ describes the plugin as a whole. For example:
 
 To import the ikiwiki plugin interface:
 
 
 To import the ikiwiki plugin interface:
 

-       use IkiWiki '2.00';
+       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,
 
 This will import several variables and functions into your plugin's
 namespace. These variables and functions are the ones most plugins need,


@@ -487,7 +506,7 @@ use the following hashes, using a page name as the key:
   destination file.
 * `%pagesources` contains the name of the source file for each page.
 
   destination file.
 * `%pagesources` contains the name of the source file for each page.
 

-Also, the %IkiWiki::version variable contains the version number for the
+Also, the `%IkiWiki::version` variable contains the version number for the

 ikiwiki program.
 
 ### Library functions
 ikiwiki program.
 
 ### Library functions


@@ -610,6 +629,16 @@ 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.
 
 
 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
 #### `will_render($$)`
 
 Given a page name and a destination file name (not including the base


@@ -697,11 +726,15 @@ 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.
 
 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($$)`
+#### `targetpage($$;$)`

 
 Passed a page and an extension, returns the filename that page will be
 rendered to.
 
 
 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`.
+

 ## Miscellaneous
 
 ### Internal use pages
 ## Miscellaneous
 
 ### Internal use pages


@@ -821,6 +854,30 @@ it up in the history.
 
 It's ok if this is not implemented, and throws an error.
 
 
 It's ok if this is not implemented, and throws an error.
 

+#### `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 exit
+nonzero, 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.
+

 ### PageSpec plugins
 
 It's also possible to write plugins that add new functions to
 ### PageSpec plugins
 
 It's also possible to write plugins that add new functions to


@@ -848,6 +905,56 @@ 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)`
 
 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.
+
+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 "<time>".formattime(@_)."</time>";
+       });
+
+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;
+       }
+

 ### Javascript
 
 Some plugins use javascript to make ikiwiki look a bit more web-2.0-ish.
 ### Javascript
 
 Some plugins use javascript to make ikiwiki look a bit more web-2.0-ish.