stangelandcl / hoedown

Standards compliant, fast, secure markdown processing library in C

Hoedown

Hoedown is a revived fork of Sundown, the Markdown parser based on the original code of the Upskirt library by Natacha Porté.

Features

• Fully standards compliant

  Hoedown passes out of the box the official Markdown v1.0.0 and v1.0.3 test suites, and has been extensively tested with additional corner cases to make sure its output is as sane as possible at all times.

• Massive extension support

  Hoedown has optional support for several (unofficial) Markdown extensions, such as non-strict emphasis, fenced code blocks, tables, autolinks, strikethrough and more.

• UTF-8 aware

  Hoedown is fully UTF-8 aware, both when parsing the source document and when generating the resulting (X)HTML code.

• Tested & Ready to be used on production

  Hoedown has been extensively security audited, and includes protection against all possible DOS attacks (stack overflows, out of memory situations, malformed Markdown syntax...) and against client attacks through malicious embedded HTML.

  We've worked very hard to make Hoedown never crash or run out of memory under any input.

• Customizable renderers

  Hoedown is not stuck with XHTML output: the Markdown parser of the library is decoupled from the renderer, so it's trivial to extend the library with custom renderers. A fully functional (X)HTML renderer is included.

• Optimized for speed

  Hoedown is written in C, with a special emphasis on performance. When wrapped on a dynamic language such as Python or Ruby, it has shown to be up to 40 times faster than other native alternatives.

• Zero-dependency

  Hoedown is a zero-dependency library composed of 4 .c files and their headers. No dependencies, no bullshit. Only standard C99 that builds everywhere.

Bindings

You can see a community-maintained list of Hoedown bindings at the wiki. There is also a migration guide available for authors of Sundown bindings.

Help us

Hoedown is all about security. If you find a (potential) security vulnerability in the library, or a way to make it crash through malicious input, please report it to us, by leaving an Issue.

Unicode character handling

Given that the Markdown spec makes no provision for Unicode character handling, Hoedown takes a conservative approach towards deciding which extended characters trigger Markdown features:

• Punctuation characters outside of the U+007F codepoint are not handled as punctuation. They are considered as normal, in-word characters for word-boundary checks.

• Whitespace characters outside of the U+007F codepoint are not considered as whitespace. They are considered as normal, in-word characters for word-boundary checks.

Install

There is nothing to install. Hoedown is composed of 4 .c files (markdown.c, buffer.c, stack.c, and autolink.c) and their headers, so just throw them in your project. Zero-dependency means zero-dependency. You might want to include html.c, html_smartypants.c and escape.c if you want to use the included XHTML renderer, or write your own renderer. Either way, it's all fun and joy.

If you are hardcore, you can use the included Makefile to build Hoedown into a dynamic library, or to build the sample hoedown executable, which is just a commandline Markdown to XHTML parser.