[[template id=plugin name=graphviz author="[[JoshTriplett]]"]]
[[tag type/chrome type/format]]

This plugin allows embedding [graphviz](http://www.graphviz.org/) graphs in a
page.  Example usage:

	\[[graph src="a -> b -> c; a -> c;"]]

Note that graphs will only show up in previews if your browser has
[[wikipedia data: URI]] support, or if the same graph already exists on that
page.

Security implications: graphviz does not seem to have any syntax exploitable to
perform file access or shell commands on the server.  However, the graphviz
plugin does make denial of service attacks somewhat easier: any user with edit
privileges can use this plugin to create large files without the need to send
large amounts of data, allowing them to more quickly fill the disk, run the
server out of memory, or use up large amounts of bandwidth.  Any user can
already do these things with just the core of ikiwiki, but the graphviz plugin
allows for an amplification attack, since users can send less data to use large
amounts of processing time and disk usage.

The `graph` directive supports the following parameters:

- `src` - The graphviz source to render.
- `type` - The type of graph to render: `graph` or `digraph`.  Defaults to
  `digraph`.
- `prog` - The graphviz program to render with: `dot`, `neato`, `fdp`, `twopi`,
  or `circo`.  Defaults to `dot`.
- `height`, `width` - Limit the size of the graph to a given height and width,
  in inches. You must specify both to limit the size; otherwise, graphviz will
  choose a size, without any limit.

[[if test="enabled(graphviz)" then="""
Some example graphs:

[[graph src="a -> b -> c; a -> b;"]]
[[graph src="a -- b -- c -- a;" prog="circo" type="graph"]]
"""]]

This plugin uses the [[cpan Digest::SHA1]] perl module.
