diff --git a/configure b/configure
index c918cd73448db..cf74de8f9d46a 100755
--- a/configure
+++ b/configure
@@ -684,7 +684,7 @@ do
       isaac linenoise sync test \
       arch/i386 arch/x86_64 arch/arm arch/mips  \
       libuv libuv/src/ares libuv/src/eio libuv/src/ev \
-      jemalloc
+      jemalloc sundown/src sundown/html
     do
       make_dir $t/rt/stage$s/$i
     done
diff --git a/mk/rt.mk b/mk/rt.mk
index 1b818bfee4151..fb4d8f7c734e8 100644
--- a/mk/rt.mk
+++ b/mk/rt.mk
@@ -82,7 +82,16 @@ RUNTIME_CXXS_$(1)_$(2) := \
               rt/rust_android_dummy.cpp \
               rt/rust_test_helpers.cpp
 
-RUNTIME_CS_$(1)_$(2) := rt/linenoise/linenoise.c rt/linenoise/utf8.c
+RUNTIME_CS_$(1)_$(2) := rt/linenoise/linenoise.c \
+			rt/linenoise/utf8.c \
+			rt/sundown/src/autolink.c \
+			rt/sundown/src/buffer.c \
+			rt/sundown/src/stack.c \
+			rt/sundown/src/markdown.c \
+			rt/sundown/html/houdini_href_e.c \
+			rt/sundown/html/houdini_html_e.c \
+			rt/sundown/html/html_smartypants.c \
+			rt/sundown/html/html.c
 
 RUNTIME_S_$(1)_$(2) := rt/arch/$$(HOST_$(1))/_context.S \
 			rt/arch/$$(HOST_$(1))/ccall.S \
@@ -117,6 +126,8 @@ RUNTIME_DEF_$(1)_$(2) := $$(RT_OUTPUT_DIR_$(1))/rustrt$$(CFG_DEF_SUFFIX_$(1))
 RUNTIME_INCS_$(1)_$(2) := -I $$(S)src/rt -I $$(S)src/rt/isaac -I $$(S)src/rt/uthash \
                      -I $$(S)src/rt/arch/$$(HOST_$(1)) \
                      -I $$(S)src/rt/linenoise \
+                     -I $$(S)src/rt/sundown/src \
+                     -I $$(S)src/rt/sundown/html \
                      -I $$(S)src/libuv/include
 RUNTIME_OBJS_$(1)_$(2) := $$(RUNTIME_CXXS_$(1)_$(2):rt/%.cpp=$$(RT_BUILD_DIR_$(1)_$(2))/%.o) \
                      $$(RUNTIME_CS_$(1)_$(2):rt/%.c=$$(RT_BUILD_DIR_$(1)_$(2))/%.o) \
diff --git a/mk/tests.mk b/mk/tests.mk
index 9fe163e509b5e..be1d3ac057cd7 100644
--- a/mk/tests.mk
+++ b/mk/tests.mk
@@ -227,8 +227,9 @@ ALL_CS := $(wildcard $(S)src/rt/*.cpp \
                      $(S)src/rt/*/*/*.cpp \
                      $(S)src/rustllvm/*.cpp)
 ALL_CS := $(filter-out $(S)src/rt/miniz.cpp \
-                       $(S)src/rt/linenoise/linenoise.c \
-                       $(S)src/rt/linenoise/utf8.c \
+		       $(wildcard $(S)src/rt/linenoise/*.c) \
+		       $(wildcard $(S)src/rt/sundown/src/*.c) \
+		       $(wildcard $(S)src/rt/sundown/html/*.c) \
 	,$(ALL_CS))
 ALL_HS := $(wildcard $(S)src/rt/*.h \
                      $(S)src/rt/*/*.h \
@@ -241,6 +242,8 @@ ALL_HS := $(filter-out $(S)src/rt/vg/valgrind.h \
                        $(S)src/rt/msvc/inttypes.h \
                        $(S)src/rt/linenoise/linenoise.h \
                        $(S)src/rt/linenoise/utf8.h \
+		       $(wildcard $(S)src/rt/sundown/src/*.h) \
+		       $(wildcard $(S)src/rt/sundown/html/*.h) \
 	,$(ALL_HS))
 
 # Run the tidy script in multiple parts to avoid huge 'echo' commands
diff --git a/src/rt/rustrt.def.in b/src/rt/rustrt.def.in
index 186fb387eea50..b87afab84eb10 100644
--- a/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@ -200,3 +200,9 @@ rust_set_stdio_container_fd
 rust_set_stdio_container_stream
 rust_uv_process_pid
 rust_uv_pipe_init
+sdhtml_renderer
+sd_markdown_new
+sd_markdown_render
+sd_markdown_free
+bufrelease
+bufnew
diff --git a/src/rt/sundown/.gitignore b/src/rt/sundown/.gitignore
new file mode 100644
index 0000000000000..4415b7917358c
--- /dev/null
+++ b/src/rt/sundown/.gitignore
@@ -0,0 +1,5 @@
+*.o
+libsundown.so*
+sundown
+smartypants
+*.exe
diff --git a/src/rt/sundown/CONTRIBUTING.md b/src/rt/sundown/CONTRIBUTING.md
new file mode 100644
index 0000000000000..7178d8cc99387
--- /dev/null
+++ b/src/rt/sundown/CONTRIBUTING.md
@@ -0,0 +1,10 @@
+Contributing to Sundown
+=======================
+
+Do not.
+
+Unfortunately, Sundown is currently frozen as we're working with the Reddit, StackOverflow and Meteor developers to design a formal Markdown standard and parser that will supersede Sundown in all these websites (and in GitHub, of course). Our goal is to deprecate Sundown altogether before the end of the year.
+
+The new parser will be smaller, faster, safer and most importantly, more consistent.
+
+Please stay tuned.
\ No newline at end of file
diff --git a/src/rt/sundown/Makefile b/src/rt/sundown/Makefile
new file mode 100644
index 0000000000000..baca6875a20a8
--- /dev/null
+++ b/src/rt/sundown/Makefile
@@ -0,0 +1,83 @@
+# Makefile
+
+# Copyright (c) 2009, Natacha Porté
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+DEPDIR=depends
+
+# "Machine-dependant" options
+#MFLAGS=-fPIC
+
+CFLAGS=-c -g -O3 -fPIC -Wall -Werror -Wsign-compare -Isrc -Ihtml
+LDFLAGS=-g -O3 -Wall -Werror 
+CC=gcc
+
+
+SUNDOWN_SRC=\
+	src/markdown.o \
+	src/stack.o \
+	src/buffer.o \
+	src/autolink.o \
+	html/html.o \
+	html/html_smartypants.o \
+	html/houdini_html_e.o \
+	html/houdini_href_e.o
+
+all:		libsundown.so sundown smartypants html_blocks
+
+.PHONY:		all clean
+
+# libraries
+
+libsundown.so:	libsundown.so.1
+	ln -f -s $^ $@
+
+libsundown.so.1: $(SUNDOWN_SRC)
+	$(CC) $(LDFLAGS) -shared -Wl $^ -o $@
+
+# executables
+
+sundown:	examples/sundown.o $(SUNDOWN_SRC)
+	$(CC) $(LDFLAGS) $^ -o $@
+
+smartypants: examples/smartypants.o $(SUNDOWN_SRC)
+	$(CC) $(LDFLAGS) $^ -o $@
+
+# perfect hashing
+html_blocks: src/html_blocks.h
+
+src/html_blocks.h: html_block_names.txt
+	gperf -N find_block_tag -H hash_block_tag -C -c -E --ignore-case $^ > $@
+
+
+# housekeeping
+clean:
+	rm -f src/*.o html/*.o examples/*.o
+	rm -f libsundown.so libsundown.so.1 sundown smartypants
+	rm -f sundown.exe smartypants.exe
+	rm -rf $(DEPDIR)
+
+
+# dependencies
+
+include $(wildcard $(DEPDIR)/*.d)
+
+
+# generic object compilations
+
+%.o:	src/%.c examples/%.c html/%.c
+	@mkdir -p $(DEPDIR)
+	@$(CC) -MM $< > $(DEPDIR)/$*.d
+	$(CC) $(CFLAGS) -o $@ $<
+
diff --git a/src/rt/sundown/Makefile.win b/src/rt/sundown/Makefile.win
new file mode 100644
index 0000000000000..ea668b2cdc1ec
--- /dev/null
+++ b/src/rt/sundown/Makefile.win
@@ -0,0 +1,33 @@
+
+CFLAGS=/O2 /EHsc /I"src/" /I"examples"/ /I"html"/
+CC=cl
+
+SUNDOWN_SRC=\
+	src\markdown.obj \
+	src\stack.obj \
+	src\buffer.obj \
+	src\autolink.obj \
+	html\html.obj \
+	html\html_smartypants.obj \
+	html\houdini_html_e.obj \
+	html\houdini_href_e.obj
+
+all: sundown.dll sundown.exe
+
+sundown.dll: $(SUNDOWN_SRC) sundown.def
+	$(CC) $(SUNDOWN_SRC) sundown.def /link /DLL $(LDFLAGS) /out:$@
+
+sundown.exe: examples\sundown.obj $(SUNDOWN_SRC)
+	$(CC) examples\sundown.obj $(SUNDOWN_SRC) /link $(LDFLAGS) /out:$@
+
+# housekeeping
+clean:
+	del $(SUNDOWN_SRC)
+	del sundown.dll sundown.exe
+	del sundown.exp sundown.lib
+
+# generic object compilations
+
+.c.obj:
+	$(CC) $(CFLAGS) /c $< /Fo$@
+
diff --git a/src/rt/sundown/README.markdown b/src/rt/sundown/README.markdown
new file mode 100644
index 0000000000000..61736025ca929
--- /dev/null
+++ b/src/rt/sundown/README.markdown
@@ -0,0 +1,131 @@
+Sundown
+=======
+
+`Sundown` is a Markdown parser based on the original code of the
+[Upskirt library](http://fossil.instinctive.eu/libupskirt/index) by Natacha Porté.
+
+Features
+--------
+
+*	**Fully standards compliant**
+
+	`Sundown` 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**
+
+	`Sundown` has optional support for several (unofficial) Markdown extensions,
+	such as non-strict emphasis, fenced code blocks, tables, autolinks,
+	strikethrough and more.
+
+*	**UTF-8 aware**
+
+	`Sundown` 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**
+
+	`Sundown` 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 `Sundown` never crash or run out of memory
+	under *any* input. `Sundown` renders all the Markdown content in GitHub and so
+	far hasn't crashed a single time.
+
+*	**Customizable renderers**
+
+	`Sundown` 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**
+
+	`Sundown` 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**
+
+	`Sundown` is a zero-dependency library composed of 3 `.c` files and their headers.
+	No dependencies, no bullshit. Only standard C99 that builds everywhere.
+
+Credits
+-------
+
+`Sundown` is based on the original Upskirt parser by Natacha Porté, with many additions
+by Vicent Marti (@vmg) and contributions from the following authors:
+
+	Ben Noordhuis, Bruno Michel, Joseph Koshy, Krzysztof Kowalczyk, Samuel Bronson,
+	Shuhei Tanuma
+
+Bindings
+--------
+
+`Sundown` is available from other programming languages thanks to these bindings developed
+by our awesome contributors.
+
+- [Redcarpet](https://github.com/vmg/redcarpet) (Ruby)
+- [RobotSkirt](https://github.com/benmills/robotskirt) (Node.js)
+- [Misaka](https://github.com/FSX/misaka) (Python)
+- [ffi-sundown](https://github.com/postmodern/ffi-sundown) (Ruby FFI)
+- [Sundown HS](https://github.com/bitonic/sundown) (Haskell)
+- [Goskirt](https://github.com/madari/goskirt) (Go)
+- [Upskirt.go](https://github.com/buu700/upskirt.go) (Go)
+- [MoonShine](https://github.com/brandonc/moonshine) (.NET)
+- [PHP-Sundown](https://github.com/chobie/php-sundown) (PHP)
+- [Sundown.net](https://github.com/txdv/sundown.net) (.NET)
+
+Help us
+-------
+
+`Sundown` 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,
+either directly via email or by opening an Issue on GitHub, and help make the web safer
+for everybody.
+
+Unicode character handling
+--------------------------
+
+Given that the Markdown spec makes no provision for Unicode character handling, `Sundown`
+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. `Sundown` is composed of 3 `.c` files (`markdown.c`,
+`buffer.c` and `array.c`), so just throw them in your project. Zero-dependency means
+zero-dependency. You might want to include `render/html.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 `Sundown` into a dynamic
+library, or to build the sample `sundown` executable, which is just a commandline
+Markdown to XHTML parser. (If gcc gives you grief about `-fPIC`, e.g. with MinGW, try
+`make MFLAGS=` instead of just `make`.)
+
+License
+-------
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+<!-- Local Variables: -->
+<!-- fill-column: 89 -->
+<!-- End: -->
diff --git a/src/rt/sundown/examples/smartypants.c b/src/rt/sundown/examples/smartypants.c
new file mode 100644
index 0000000000000..4840703bb12ec
--- /dev/null
+++ b/src/rt/sundown/examples/smartypants.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "markdown.h"
+#include "html.h"
+#include "buffer.h"
+
+#include <errno.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define READ_UNIT 1024
+#define OUTPUT_UNIT 64
+
+int
+main(int argc, char **argv)
+{
+	struct buf *ib, *ob;
+	size_t ret;
+	FILE *in = stdin;
+
+	/* opening the file if given from the command line */
+	if (argc > 1) {
+		in = fopen(argv[1], "r");
+		if (!in) {
+			fprintf(stderr, "Unable to open input file \"%s\": %s\n", argv[0], strerror(errno));
+			return 1;
+		}
+	}
+
+	/* reading everything */
+	ib = bufnew(READ_UNIT);
+	bufgrow(ib, READ_UNIT);
+	while ((ret = fread(ib->data + ib->size, 1, ib->asize - ib->size, in)) > 0) {
+		ib->size += ret;
+		bufgrow(ib, ib->size + READ_UNIT);
+	}
+
+	if (in != stdin)
+		fclose(in);
+
+	/* performing markdown parsing */
+	ob = bufnew(OUTPUT_UNIT);
+
+	sdhtml_smartypants(ob, ib->data, ib->size);
+
+	/* writing the result to stdout */
+	(void)fwrite(ob->data, 1, ob->size, stdout);
+
+	/* cleanup */
+	bufrelease(ib);
+	bufrelease(ob);
+
+	return 0;
+}
+
+/* vim: set filetype=c: */
diff --git a/src/rt/sundown/examples/sundown.c b/src/rt/sundown/examples/sundown.c
new file mode 100644
index 0000000000000..8a475dcaa3d79
--- /dev/null
+++ b/src/rt/sundown/examples/sundown.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "markdown.h"
+#include "html.h"
+#include "buffer.h"
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define READ_UNIT 1024
+#define OUTPUT_UNIT 64
+
+/* main • main function, interfacing STDIO with the parser */
+int
+main(int argc, char **argv)
+{
+	struct buf *ib, *ob;
+	int ret;
+	FILE *in = stdin;
+
+	struct sd_callbacks callbacks;
+	struct html_renderopt options;
+	struct sd_markdown *markdown;
+
+	/* opening the file if given from the command line */
+	if (argc > 1) {
+		in = fopen(argv[1], "r");
+		if (!in) {
+			fprintf(stderr,"Unable to open input file \"%s\": %s\n", argv[1], strerror(errno));
+			return 1;
+		}
+	}
+
+	/* reading everything */
+	ib = bufnew(READ_UNIT);
+	bufgrow(ib, READ_UNIT);
+	while ((ret = fread(ib->data + ib->size, 1, ib->asize - ib->size, in)) > 0) {
+		ib->size += ret;
+		bufgrow(ib, ib->size + READ_UNIT);
+	}
+
+	if (in != stdin)
+		fclose(in);
+
+	/* performing markdown parsing */
+	ob = bufnew(OUTPUT_UNIT);
+
+	sdhtml_renderer(&callbacks, &options, 0);
+	markdown = sd_markdown_new(0, 16, &callbacks, &options);
+
+	sd_markdown_render(ob, ib->data, ib->size, markdown);
+	sd_markdown_free(markdown);
+
+	/* writing the result to stdout */
+	ret = fwrite(ob->data, 1, ob->size, stdout);
+
+	/* cleanup */
+	bufrelease(ib);
+	bufrelease(ob);
+
+	return (ret < 0) ? -1 : 0;
+}
+
+/* vim: set filetype=c: */
diff --git a/src/rt/sundown/html/houdini.h b/src/rt/sundown/html/houdini.h
new file mode 100644
index 0000000000000..b4954c02f6790
--- /dev/null
+++ b/src/rt/sundown/html/houdini.h
@@ -0,0 +1,37 @@
+#ifndef HOUDINI_H__
+#define HOUDINI_H__
+
+#include "buffer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef HOUDINI_USE_LOCALE
+#	define _isxdigit(c) isxdigit(c)
+#	define _isdigit(c) isdigit(c)
+#else
+/*
+ * Helper _isdigit methods -- do not trust the current locale
+ * */
+#	define _isxdigit(c) (strchr("0123456789ABCDEFabcdef", (c)) != NULL)
+#	define _isdigit(c) ((c) >= '0' && (c) <= '9')
+#endif
+
+extern void houdini_escape_html(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_escape_html0(struct buf *ob, const uint8_t *src, size_t size, int secure);
+extern void houdini_unescape_html(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_escape_xml(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_escape_uri(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_escape_url(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_escape_href(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_unescape_uri(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_unescape_url(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_escape_js(struct buf *ob, const uint8_t *src, size_t size);
+extern void houdini_unescape_js(struct buf *ob, const uint8_t *src, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/rt/sundown/html/houdini_href_e.c b/src/rt/sundown/html/houdini_href_e.c
new file mode 100644
index 0000000000000..981b3b17e4153
--- /dev/null
+++ b/src/rt/sundown/html/houdini_href_e.c
@@ -0,0 +1,108 @@
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "houdini.h"
+
+#define ESCAPE_GROW_FACTOR(x) (((x) * 12) / 10)
+
+/*
+ * The following characters will not be escaped:
+ *
+ *		-_.+!*'(),%#@?=;:/,+&$ alphanum
+ *
+ * Note that this character set is the addition of:
+ *
+ *	- The characters which are safe to be in an URL
+ *	- The characters which are *not* safe to be in
+ *	an URL because they are RESERVED characters.
+ *
+ * We asume (lazily) that any RESERVED char that
+ * appears inside an URL is actually meant to
+ * have its native function (i.e. as an URL 
+ * component/separator) and hence needs no escaping.
+ *
+ * There are two exceptions: the chacters & (amp)
+ * and ' (single quote) do not appear in the table.
+ * They are meant to appear in the URL as components,
+ * yet they require special HTML-entity escaping
+ * to generate valid HTML markup.
+ *
+ * All other characters will be escaped to %XX.
+ *
+ */
+static const char HREF_SAFE[] = {
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 
+	0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 
+	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+};
+
+void
+houdini_escape_href(struct buf *ob, const uint8_t *src, size_t size)
+{
+	static const char hex_chars[] = "0123456789ABCDEF";
+	size_t  i = 0, org;
+	char hex_str[3];
+
+	bufgrow(ob, ESCAPE_GROW_FACTOR(size));
+	hex_str[0] = '%';
+
+	while (i < size) {
+		org = i;
+		while (i < size && HREF_SAFE[src[i]] != 0)
+			i++;
+
+		if (i > org)
+			bufput(ob, src + org, i - org);
+
+		/* escaping */
+		if (i >= size)
+			break;
+
+		switch (src[i]) {
+		/* amp appears all the time in URLs, but needs
+		 * HTML-entity escaping to be inside an href */
+		case '&': 
+			BUFPUTSL(ob, "&amp;");
+			break;
+
+		/* the single quote is a valid URL character
+		 * according to the standard; it needs HTML
+		 * entity escaping too */
+		case '\'':
+			BUFPUTSL(ob, "&#x27;");
+			break;
+		
+		/* the space can be escaped to %20 or a plus
+		 * sign. we're going with the generic escape
+		 * for now. the plus thing is more commonly seen
+		 * when building GET strings */
+#if 0
+		case ' ':
+			bufputc(ob, '+');
+			break;
+#endif
+
+		/* every other character goes with a %XX escaping */
+		default:
+			hex_str[1] = hex_chars[(src[i] >> 4) & 0xF];
+			hex_str[2] = hex_chars[src[i] & 0xF];
+			bufput(ob, hex_str, 3);
+		}
+
+		i++;
+	}
+}
diff --git a/src/rt/sundown/html/houdini_html_e.c b/src/rt/sundown/html/houdini_html_e.c
new file mode 100644
index 0000000000000..d9bbf187d825c
--- /dev/null
+++ b/src/rt/sundown/html/houdini_html_e.c
@@ -0,0 +1,84 @@
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "houdini.h"
+
+#define ESCAPE_GROW_FACTOR(x) (((x) * 12) / 10) /* this is very scientific, yes */
+
+/**
+ * According to the OWASP rules:
+ *
+ * & --> &amp;
+ * < --> &lt;
+ * > --> &gt;
+ * " --> &quot;
+ * ' --> &#x27;     &apos; is not recommended
+ * / --> &#x2F;     forward slash is included as it helps end an HTML entity
+ *
+ */
+static const char HTML_ESCAPE_TABLE[] = {
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 1, 0, 0, 0, 2, 3, 0, 0, 0, 0, 0, 0, 0, 4, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 6, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+};
+
+static const char *HTML_ESCAPES[] = {
+        "",
+        "&quot;",
+        "&amp;",
+        "&#39;",
+        "&#47;",
+        "&lt;",
+        "&gt;"
+};
+
+void
+houdini_escape_html0(struct buf *ob, const uint8_t *src, size_t size, int secure)
+{
+	size_t i = 0, org, esc = 0;
+
+	bufgrow(ob, ESCAPE_GROW_FACTOR(size));
+
+	while (i < size) {
+		org = i;
+		while (i < size && (esc = HTML_ESCAPE_TABLE[src[i]]) == 0)
+			i++;
+
+		if (i > org)
+			bufput(ob, src + org, i - org);
+
+		/* escaping */
+		if (i >= size)
+			break;
+
+		/* The forward slash is only escaped in secure mode */
+		if (src[i] == '/' && !secure) {
+			bufputc(ob, '/');
+		} else {
+			bufputs(ob, HTML_ESCAPES[esc]);
+		}
+
+		i++;
+	}
+}
+
+void
+houdini_escape_html(struct buf *ob, const uint8_t *src, size_t size)
+{
+	houdini_escape_html0(ob, src, size, 1);
+}
+
diff --git a/src/rt/sundown/html/html.c b/src/rt/sundown/html/html.c
new file mode 100755
index 0000000000000..7f08ee8ef1b97
--- /dev/null
+++ b/src/rt/sundown/html/html.c
@@ -0,0 +1,635 @@
+/*
+ * Copyright (c) 2009, Natacha Porté
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "markdown.h"
+#include "html.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#include "houdini.h"
+
+#define USE_XHTML(opt) (opt->flags & HTML_USE_XHTML)
+
+int
+sdhtml_is_tag(const uint8_t *tag_data, size_t tag_size, const char *tagname)
+{
+	size_t i;
+	int closed = 0;
+
+	if (tag_size < 3 || tag_data[0] != '<')
+		return HTML_TAG_NONE;
+
+	i = 1;
+
+	if (tag_data[i] == '/') {
+		closed = 1;
+		i++;
+	}
+
+	for (; i < tag_size; ++i, ++tagname) {
+		if (*tagname == 0)
+			break;
+
+		if (tag_data[i] != *tagname)
+			return HTML_TAG_NONE;
+	}
+
+	if (i == tag_size)
+		return HTML_TAG_NONE;
+
+	if (isspace(tag_data[i]) || tag_data[i] == '>')
+		return closed ? HTML_TAG_CLOSE : HTML_TAG_OPEN;
+
+	return HTML_TAG_NONE;
+}
+
+static inline void escape_html(struct buf *ob, const uint8_t *source, size_t length)
+{
+	houdini_escape_html0(ob, source, length, 0);
+}
+
+static inline void escape_href(struct buf *ob, const uint8_t *source, size_t length)
+{
+	houdini_escape_href(ob, source, length);
+}
+
+/********************
+ * GENERIC RENDERER *
+ ********************/
+static int
+rndr_autolink(struct buf *ob, const struct buf *link, enum mkd_autolink type, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	if (!link || !link->size)
+		return 0;
+
+	if ((options->flags & HTML_SAFELINK) != 0 &&
+		!sd_autolink_issafe(link->data, link->size) &&
+		type != MKDA_EMAIL)
+		return 0;
+
+	BUFPUTSL(ob, "<a href=\"");
+	if (type == MKDA_EMAIL)
+		BUFPUTSL(ob, "mailto:");
+	escape_href(ob, link->data, link->size);
+
+	if (options->link_attributes) {
+		bufputc(ob, '\"');
+		options->link_attributes(ob, link, opaque);
+		bufputc(ob, '>');
+	} else {
+		BUFPUTSL(ob, "\">");
+	}
+
+	/*
+	 * Pretty printing: if we get an email address as
+	 * an actual URI, e.g. `mailto:foo@bar.com`, we don't
+	 * want to print the `mailto:` prefix
+	 */
+	if (bufprefix(link, "mailto:") == 0) {
+		escape_html(ob, link->data + 7, link->size - 7);
+	} else {
+		escape_html(ob, link->data, link->size);
+	}
+
+	BUFPUTSL(ob, "</a>");
+
+	return 1;
+}
+
+static void
+rndr_blockcode(struct buf *ob, const struct buf *text, const struct buf *lang, void *opaque)
+{
+	if (ob->size) bufputc(ob, '\n');
+
+	if (lang && lang->size) {
+		size_t i, cls;
+		BUFPUTSL(ob, "<pre><code class=\"");
+
+		for (i = 0, cls = 0; i < lang->size; ++i, ++cls) {
+			while (i < lang->size && isspace(lang->data[i]))
+				i++;
+
+			if (i < lang->size) {
+				size_t org = i;
+				while (i < lang->size && !isspace(lang->data[i]))
+					i++;
+
+				if (lang->data[org] == '.')
+					org++;
+
+				if (cls) bufputc(ob, ' ');
+				escape_html(ob, lang->data + org, i - org);
+			}
+		}
+
+		BUFPUTSL(ob, "\">");
+	} else
+		BUFPUTSL(ob, "<pre><code>");
+
+	if (text)
+		escape_html(ob, text->data, text->size);
+
+	BUFPUTSL(ob, "</code></pre>\n");
+}
+
+static void
+rndr_blockquote(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (ob->size) bufputc(ob, '\n');
+	BUFPUTSL(ob, "<blockquote>\n");
+	if (text) bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</blockquote>\n");
+}
+
+static int
+rndr_codespan(struct buf *ob, const struct buf *text, void *opaque)
+{
+	BUFPUTSL(ob, "<code>");
+	if (text) escape_html(ob, text->data, text->size);
+	BUFPUTSL(ob, "</code>");
+	return 1;
+}
+
+static int
+rndr_strikethrough(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (!text || !text->size)
+		return 0;
+
+	BUFPUTSL(ob, "<del>");
+	bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</del>");
+	return 1;
+}
+
+static int
+rndr_double_emphasis(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (!text || !text->size)
+		return 0;
+
+	BUFPUTSL(ob, "<strong>");
+	bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</strong>");
+
+	return 1;
+}
+
+static int
+rndr_emphasis(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (!text || !text->size) return 0;
+	BUFPUTSL(ob, "<em>");
+	if (text) bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</em>");
+	return 1;
+}
+
+static int
+rndr_linebreak(struct buf *ob, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+	bufputs(ob, USE_XHTML(options) ? "<br/>\n" : "<br>\n");
+	return 1;
+}
+
+static void
+rndr_header(struct buf *ob, const struct buf *text, int level, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	if (ob->size)
+		bufputc(ob, '\n');
+
+	if (options->flags & HTML_TOC)
+		bufprintf(ob, "<h%d id=\"toc_%d\">", level, options->toc_data.header_count++);
+	else
+		bufprintf(ob, "<h%d>", level);
+
+	if (text) bufput(ob, text->data, text->size);
+	bufprintf(ob, "</h%d>\n", level);
+}
+
+static int
+rndr_link(struct buf *ob, const struct buf *link, const struct buf *title, const struct buf *content, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	if (link != NULL && (options->flags & HTML_SAFELINK) != 0 && !sd_autolink_issafe(link->data, link->size))
+		return 0;
+
+	BUFPUTSL(ob, "<a href=\"");
+
+	if (link && link->size)
+		escape_href(ob, link->data, link->size);
+
+	if (title && title->size) {
+		BUFPUTSL(ob, "\" title=\"");
+		escape_html(ob, title->data, title->size);
+	}
+
+	if (options->link_attributes) {
+		bufputc(ob, '\"');
+		options->link_attributes(ob, link, opaque);
+		bufputc(ob, '>');
+	} else {
+		BUFPUTSL(ob, "\">");
+	}
+
+	if (content && content->size) bufput(ob, content->data, content->size);
+	BUFPUTSL(ob, "</a>");
+	return 1;
+}
+
+static void
+rndr_list(struct buf *ob, const struct buf *text, int flags, void *opaque)
+{
+	if (ob->size) bufputc(ob, '\n');
+	bufput(ob, flags & MKD_LIST_ORDERED ? "<ol>\n" : "<ul>\n", 5);
+	if (text) bufput(ob, text->data, text->size);
+	bufput(ob, flags & MKD_LIST_ORDERED ? "</ol>\n" : "</ul>\n", 6);
+}
+
+static void
+rndr_listitem(struct buf *ob, const struct buf *text, int flags, void *opaque)
+{
+	BUFPUTSL(ob, "<li>");
+	if (text) {
+		size_t size = text->size;
+		while (size && text->data[size - 1] == '\n')
+			size--;
+
+		bufput(ob, text->data, size);
+	}
+	BUFPUTSL(ob, "</li>\n");
+}
+
+static void
+rndr_paragraph(struct buf *ob, const struct buf *text, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+	size_t i = 0;
+
+	if (ob->size) bufputc(ob, '\n');
+
+	if (!text || !text->size)
+		return;
+
+	while (i < text->size && isspace(text->data[i])) i++;
+
+	if (i == text->size)
+		return;
+
+	BUFPUTSL(ob, "<p>");
+	if (options->flags & HTML_HARD_WRAP) {
+		size_t org;
+		while (i < text->size) {
+			org = i;
+			while (i < text->size && text->data[i] != '\n')
+				i++;
+
+			if (i > org)
+				bufput(ob, text->data + org, i - org);
+
+			/*
+			 * do not insert a line break if this newline
+			 * is the last character on the paragraph
+			 */
+			if (i >= text->size - 1)
+				break;
+
+			rndr_linebreak(ob, opaque);
+			i++;
+		}
+	} else {
+		bufput(ob, &text->data[i], text->size - i);
+	}
+	BUFPUTSL(ob, "</p>\n");
+}
+
+static void
+rndr_raw_block(struct buf *ob, const struct buf *text, void *opaque)
+{
+	size_t org, sz;
+	if (!text) return;
+	sz = text->size;
+	while (sz > 0 && text->data[sz - 1] == '\n') sz--;
+	org = 0;
+	while (org < sz && text->data[org] == '\n') org++;
+	if (org >= sz) return;
+	if (ob->size) bufputc(ob, '\n');
+	bufput(ob, text->data + org, sz - org);
+	bufputc(ob, '\n');
+}
+
+static int
+rndr_triple_emphasis(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (!text || !text->size) return 0;
+	BUFPUTSL(ob, "<strong><em>");
+	bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</em></strong>");
+	return 1;
+}
+
+static void
+rndr_hrule(struct buf *ob, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+	if (ob->size) bufputc(ob, '\n');
+	bufputs(ob, USE_XHTML(options) ? "<hr/>\n" : "<hr>\n");
+}
+
+static int
+rndr_image(struct buf *ob, const struct buf *link, const struct buf *title, const struct buf *alt, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+	if (!link || !link->size) return 0;
+
+	BUFPUTSL(ob, "<img src=\"");
+	escape_href(ob, link->data, link->size);
+	BUFPUTSL(ob, "\" alt=\"");
+
+	if (alt && alt->size)
+		escape_html(ob, alt->data, alt->size);
+
+	if (title && title->size) {
+		BUFPUTSL(ob, "\" title=\"");
+		escape_html(ob, title->data, title->size); }
+
+	bufputs(ob, USE_XHTML(options) ? "\"/>" : "\">");
+	return 1;
+}
+
+static int
+rndr_raw_html(struct buf *ob, const struct buf *text, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	/* HTML_ESCAPE overrides SKIP_HTML, SKIP_STYLE, SKIP_LINKS and SKIP_IMAGES
+	* It doens't see if there are any valid tags, just escape all of them. */
+	if((options->flags & HTML_ESCAPE) != 0) {
+		escape_html(ob, text->data, text->size);
+		return 1;
+	}
+
+	if ((options->flags & HTML_SKIP_HTML) != 0)
+		return 1;
+
+	if ((options->flags & HTML_SKIP_STYLE) != 0 &&
+		sdhtml_is_tag(text->data, text->size, "style"))
+		return 1;
+
+	if ((options->flags & HTML_SKIP_LINKS) != 0 &&
+		sdhtml_is_tag(text->data, text->size, "a"))
+		return 1;
+
+	if ((options->flags & HTML_SKIP_IMAGES) != 0 &&
+		sdhtml_is_tag(text->data, text->size, "img"))
+		return 1;
+
+	bufput(ob, text->data, text->size);
+	return 1;
+}
+
+static void
+rndr_table(struct buf *ob, const struct buf *header, const struct buf *body, void *opaque)
+{
+	if (ob->size) bufputc(ob, '\n');
+	BUFPUTSL(ob, "<table><thead>\n");
+	if (header)
+		bufput(ob, header->data, header->size);
+	BUFPUTSL(ob, "</thead><tbody>\n");
+	if (body)
+		bufput(ob, body->data, body->size);
+	BUFPUTSL(ob, "</tbody></table>\n");
+}
+
+static void
+rndr_tablerow(struct buf *ob, const struct buf *text, void *opaque)
+{
+	BUFPUTSL(ob, "<tr>\n");
+	if (text)
+		bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</tr>\n");
+}
+
+static void
+rndr_tablecell(struct buf *ob, const struct buf *text, int flags, void *opaque)
+{
+	if (flags & MKD_TABLE_HEADER) {
+		BUFPUTSL(ob, "<th");
+	} else {
+		BUFPUTSL(ob, "<td");
+	}
+
+	switch (flags & MKD_TABLE_ALIGNMASK) {
+	case MKD_TABLE_ALIGN_CENTER:
+		BUFPUTSL(ob, " align=\"center\">");
+		break;
+
+	case MKD_TABLE_ALIGN_L:
+		BUFPUTSL(ob, " align=\"left\">");
+		break;
+
+	case MKD_TABLE_ALIGN_R:
+		BUFPUTSL(ob, " align=\"right\">");
+		break;
+
+	default:
+		BUFPUTSL(ob, ">");
+	}
+
+	if (text)
+		bufput(ob, text->data, text->size);
+
+	if (flags & MKD_TABLE_HEADER) {
+		BUFPUTSL(ob, "</th>\n");
+	} else {
+		BUFPUTSL(ob, "</td>\n");
+	}
+}
+
+static int
+rndr_superscript(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (!text || !text->size) return 0;
+	BUFPUTSL(ob, "<sup>");
+	bufput(ob, text->data, text->size);
+	BUFPUTSL(ob, "</sup>");
+	return 1;
+}
+
+static void
+rndr_normal_text(struct buf *ob, const struct buf *text, void *opaque)
+{
+	if (text)
+		escape_html(ob, text->data, text->size);
+}
+
+static void
+toc_header(struct buf *ob, const struct buf *text, int level, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	/* set the level offset if this is the first header
+	 * we're parsing for the document */
+	if (options->toc_data.current_level == 0) {
+		options->toc_data.level_offset = level - 1;
+	}
+	level -= options->toc_data.level_offset;
+
+	if (level > options->toc_data.current_level) {
+		while (level > options->toc_data.current_level) {
+			BUFPUTSL(ob, "<ul>\n<li>\n");
+			options->toc_data.current_level++;
+		}
+	} else if (level < options->toc_data.current_level) {
+		BUFPUTSL(ob, "</li>\n");
+		while (level < options->toc_data.current_level) {
+			BUFPUTSL(ob, "</ul>\n</li>\n");
+			options->toc_data.current_level--;
+		}
+		BUFPUTSL(ob,"<li>\n");
+	} else {
+		BUFPUTSL(ob,"</li>\n<li>\n");
+	}
+
+	bufprintf(ob, "<a href=\"#toc_%d\">", options->toc_data.header_count++);
+	if (text)
+		escape_html(ob, text->data, text->size);
+	BUFPUTSL(ob, "</a>\n");
+}
+
+static int
+toc_link(struct buf *ob, const struct buf *link, const struct buf *title, const struct buf *content, void *opaque)
+{
+	if (content && content->size)
+		bufput(ob, content->data, content->size);
+	return 1;
+}
+
+static void
+toc_finalize(struct buf *ob, void *opaque)
+{
+	struct html_renderopt *options = opaque;
+
+	while (options->toc_data.current_level > 0) {
+		BUFPUTSL(ob, "</li>\n</ul>\n");
+		options->toc_data.current_level--;
+	}
+}
+
+void
+sdhtml_toc_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options)
+{
+	static const struct sd_callbacks cb_default = {
+		NULL,
+		NULL,
+		NULL,
+		toc_header,
+		NULL,
+		NULL,
+		NULL,
+		NULL,
+		NULL,
+		NULL,
+		NULL,
+
+		NULL,
+		rndr_codespan,
+		rndr_double_emphasis,
+		rndr_emphasis,
+		NULL,
+		NULL,
+		toc_link,
+		NULL,
+		rndr_triple_emphasis,
+		rndr_strikethrough,
+		rndr_superscript,
+
+		NULL,
+		NULL,
+
+		NULL,
+		toc_finalize,
+	};
+
+	memset(options, 0x0, sizeof(struct html_renderopt));
+	options->flags = HTML_TOC;
+
+	memcpy(callbacks, &cb_default, sizeof(struct sd_callbacks));
+}
+
+void
+sdhtml_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options, unsigned int render_flags)
+{
+	static const struct sd_callbacks cb_default = {
+		rndr_blockcode,
+		rndr_blockquote,
+		rndr_raw_block,
+		rndr_header,
+		rndr_hrule,
+		rndr_list,
+		rndr_listitem,
+		rndr_paragraph,
+		rndr_table,
+		rndr_tablerow,
+		rndr_tablecell,
+
+		rndr_autolink,
+		rndr_codespan,
+		rndr_double_emphasis,
+		rndr_emphasis,
+		rndr_image,
+		rndr_linebreak,
+		rndr_link,
+		rndr_raw_html,
+		rndr_triple_emphasis,
+		rndr_strikethrough,
+		rndr_superscript,
+
+		NULL,
+		rndr_normal_text,
+
+		NULL,
+		NULL,
+	};
+
+	/* Prepare the options pointer */
+	memset(options, 0x0, sizeof(struct html_renderopt));
+	options->flags = render_flags;
+
+	/* Prepare the callbacks */
+	memcpy(callbacks, &cb_default, sizeof(struct sd_callbacks));
+
+	if (render_flags & HTML_SKIP_IMAGES)
+		callbacks->image = NULL;
+
+	if (render_flags & HTML_SKIP_LINKS) {
+		callbacks->link = NULL;
+		callbacks->autolink = NULL;
+	}
+
+	if (render_flags & HTML_SKIP_HTML || render_flags & HTML_ESCAPE)
+		callbacks->blockhtml = NULL;
+}
diff --git a/src/rt/sundown/html/html.h b/src/rt/sundown/html/html.h
new file mode 100644
index 0000000000000..4c8810d471c92
--- /dev/null
+++ b/src/rt/sundown/html/html.h
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef UPSKIRT_HTML_H
+#define UPSKIRT_HTML_H
+
+#include "markdown.h"
+#include "buffer.h"
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct html_renderopt {
+	struct {
+		int header_count;
+		int current_level;
+		int level_offset;
+	} toc_data;
+
+	unsigned int flags;
+
+	/* extra callbacks */
+	void (*link_attributes)(struct buf *ob, const struct buf *url, void *self);
+};
+
+typedef enum {
+	HTML_SKIP_HTML = (1 << 0),
+	HTML_SKIP_STYLE = (1 << 1),
+	HTML_SKIP_IMAGES = (1 << 2),
+	HTML_SKIP_LINKS = (1 << 3),
+	HTML_EXPAND_TABS = (1 << 4),
+	HTML_SAFELINK = (1 << 5),
+	HTML_TOC = (1 << 6),
+	HTML_HARD_WRAP = (1 << 7),
+	HTML_USE_XHTML = (1 << 8),
+	HTML_ESCAPE = (1 << 9),
+} html_render_mode;
+
+typedef enum {
+	HTML_TAG_NONE = 0,
+	HTML_TAG_OPEN,
+	HTML_TAG_CLOSE,
+} html_tag;
+
+int
+sdhtml_is_tag(const uint8_t *tag_data, size_t tag_size, const char *tagname);
+
+extern void
+sdhtml_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options_ptr, unsigned int render_flags);
+
+extern void
+sdhtml_toc_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options_ptr);
+
+extern void
+sdhtml_smartypants(struct buf *ob, const uint8_t *text, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
diff --git a/src/rt/sundown/html/html_smartypants.c b/src/rt/sundown/html/html_smartypants.c
new file mode 100644
index 0000000000000..367c26aeb9cc9
--- /dev/null
+++ b/src/rt/sundown/html/html_smartypants.c
@@ -0,0 +1,389 @@
+/*
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "buffer.h"
+#include "html.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#if defined(_WIN32)
+#define snprintf	_snprintf		
+#endif
+
+struct smartypants_data {
+	int in_squote;
+	int in_dquote;
+};
+
+static size_t smartypants_cb__ltag(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__dquote(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__amp(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__period(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__number(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__dash(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__parens(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__squote(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__backtick(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+static size_t smartypants_cb__escape(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size);
+
+static size_t (*smartypants_cb_ptrs[])
+	(struct buf *, struct smartypants_data *, uint8_t, const uint8_t *, size_t) =
+{
+	NULL,					/* 0 */
+	smartypants_cb__dash,	/* 1 */
+	smartypants_cb__parens,	/* 2 */
+	smartypants_cb__squote, /* 3 */
+	smartypants_cb__dquote, /* 4 */
+	smartypants_cb__amp,	/* 5 */
+	smartypants_cb__period,	/* 6 */
+	smartypants_cb__number,	/* 7 */
+	smartypants_cb__ltag,	/* 8 */
+	smartypants_cb__backtick, /* 9 */
+	smartypants_cb__escape, /* 10 */
+};
+
+static const uint8_t smartypants_cb_chars[] = {
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 4, 0, 0, 0, 5, 3, 2, 0, 0, 0, 0, 1, 6, 0,
+	0, 7, 0, 7, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 0, 0, 0,
+	9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+};
+
+static inline int
+word_boundary(uint8_t c)
+{
+	return c == 0 || isspace(c) || ispunct(c);
+}
+
+static int
+smartypants_quotes(struct buf *ob, uint8_t previous_char, uint8_t next_char, uint8_t quote, int *is_open)
+{
+	char ent[8];
+
+	if (*is_open && !word_boundary(next_char))
+		return 0;
+
+	if (!(*is_open) && !word_boundary(previous_char))
+		return 0;
+
+	snprintf(ent, sizeof(ent), "&%c%cquo;", (*is_open) ? 'r' : 'l', quote);
+	*is_open = !(*is_open);
+	bufputs(ob, ent);
+	return 1;
+}
+
+static size_t
+smartypants_cb__squote(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size >= 2) {
+		uint8_t t1 = tolower(text[1]);
+
+		if (t1 == '\'') {
+			if (smartypants_quotes(ob, previous_char, size >= 3 ? text[2] : 0, 'd', &smrt->in_dquote))
+				return 1;
+		}
+
+		if ((t1 == 's' || t1 == 't' || t1 == 'm' || t1 == 'd') &&
+			(size == 3 || word_boundary(text[2]))) {
+			BUFPUTSL(ob, "&rsquo;");
+			return 0;
+		}
+
+		if (size >= 3) {
+			uint8_t t2 = tolower(text[2]);
+
+			if (((t1 == 'r' && t2 == 'e') ||
+				(t1 == 'l' && t2 == 'l') ||
+				(t1 == 'v' && t2 == 'e')) &&
+				(size == 4 || word_boundary(text[3]))) {
+				BUFPUTSL(ob, "&rsquo;");
+				return 0;
+			}
+		}
+	}
+
+	if (smartypants_quotes(ob, previous_char, size > 0 ? text[1] : 0, 's', &smrt->in_squote))
+		return 0;
+
+	bufputc(ob, text[0]);
+	return 0;
+}
+
+static size_t
+smartypants_cb__parens(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size >= 3) {
+		uint8_t t1 = tolower(text[1]);
+		uint8_t t2 = tolower(text[2]);
+
+		if (t1 == 'c' && t2 == ')') {
+			BUFPUTSL(ob, "&copy;");
+			return 2;
+		}
+
+		if (t1 == 'r' && t2 == ')') {
+			BUFPUTSL(ob, "&reg;");
+			return 2;
+		}
+
+		if (size >= 4 && t1 == 't' && t2 == 'm' && text[3] == ')') {
+			BUFPUTSL(ob, "&trade;");
+			return 3;
+		}
+	}
+
+	bufputc(ob, text[0]);
+	return 0;
+}
+
+static size_t
+smartypants_cb__dash(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size >= 3 && text[1] == '-' && text[2] == '-') {
+		BUFPUTSL(ob, "&mdash;");
+		return 2;
+	}
+
+	if (size >= 2 && text[1] == '-') {
+		BUFPUTSL(ob, "&ndash;");
+		return 1;
+	}
+
+	bufputc(ob, text[0]);
+	return 0;
+}
+
+static size_t
+smartypants_cb__amp(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size >= 6 && memcmp(text, "&quot;", 6) == 0) {
+		if (smartypants_quotes(ob, previous_char, size >= 7 ? text[6] : 0, 'd', &smrt->in_dquote))
+			return 5;
+	}
+
+	if (size >= 4 && memcmp(text, "&#0;", 4) == 0)
+		return 3;
+
+	bufputc(ob, '&');
+	return 0;
+}
+
+static size_t
+smartypants_cb__period(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size >= 3 && text[1] == '.' && text[2] == '.') {
+		BUFPUTSL(ob, "&hellip;");
+		return 2;
+	}
+
+	if (size >= 5 && text[1] == ' ' && text[2] == '.' && text[3] == ' ' && text[4] == '.') {
+		BUFPUTSL(ob, "&hellip;");
+		return 4;
+	}
+
+	bufputc(ob, text[0]);
+	return 0;
+}
+
+static size_t
+smartypants_cb__backtick(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size >= 2 && text[1] == '`') {
+		if (smartypants_quotes(ob, previous_char, size >= 3 ? text[2] : 0, 'd', &smrt->in_dquote))
+			return 1;
+	}
+
+	return 0;
+}
+
+static size_t
+smartypants_cb__number(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (word_boundary(previous_char) && size >= 3) {
+		if (text[0] == '1' && text[1] == '/' && text[2] == '2') {
+			if (size == 3 || word_boundary(text[3])) {
+				BUFPUTSL(ob, "&frac12;");
+				return 2;
+			}
+		}
+
+		if (text[0] == '1' && text[1] == '/' && text[2] == '4') {
+			if (size == 3 || word_boundary(text[3]) ||
+				(size >= 5 && tolower(text[3]) == 't' && tolower(text[4]) == 'h')) {
+				BUFPUTSL(ob, "&frac14;");
+				return 2;
+			}
+		}
+
+		if (text[0] == '3' && text[1] == '/' && text[2] == '4') {
+			if (size == 3 || word_boundary(text[3]) ||
+				(size >= 6 && tolower(text[3]) == 't' && tolower(text[4]) == 'h' && tolower(text[5]) == 's')) {
+				BUFPUTSL(ob, "&frac34;");
+				return 2;
+			}
+		}
+	}
+
+	bufputc(ob, text[0]);
+	return 0;
+}
+
+static size_t
+smartypants_cb__dquote(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (!smartypants_quotes(ob, previous_char, size > 0 ? text[1] : 0, 'd', &smrt->in_dquote))
+		BUFPUTSL(ob, "&quot;");
+
+	return 0;
+}
+
+static size_t
+smartypants_cb__ltag(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	static const char *skip_tags[] = {
+	  "pre", "code", "var", "samp", "kbd", "math", "script", "style"
+	};
+	static const size_t skip_tags_count = 8;
+
+	size_t tag, i = 0;
+
+	while (i < size && text[i] != '>')
+		i++;
+
+	for (tag = 0; tag < skip_tags_count; ++tag) {
+		if (sdhtml_is_tag(text, size, skip_tags[tag]) == HTML_TAG_OPEN)
+			break;
+	}
+
+	if (tag < skip_tags_count) {
+		for (;;) {
+			while (i < size && text[i] != '<')
+				i++;
+
+			if (i == size)
+				break;
+
+			if (sdhtml_is_tag(text + i, size - i, skip_tags[tag]) == HTML_TAG_CLOSE)
+				break;
+
+			i++;
+		}
+
+		while (i < size && text[i] != '>')
+			i++;
+	}
+
+	bufput(ob, text, i + 1);
+	return i;
+}
+
+static size_t
+smartypants_cb__escape(struct buf *ob, struct smartypants_data *smrt, uint8_t previous_char, const uint8_t *text, size_t size)
+{
+	if (size < 2)
+		return 0;
+
+	switch (text[1]) {
+	case '\\':
+	case '"':
+	case '\'':
+	case '.':
+	case '-':
+	case '`':
+		bufputc(ob, text[1]);
+		return 1;
+
+	default:
+		bufputc(ob, '\\');
+		return 0;
+	}
+}
+
+#if 0
+static struct {
+    uint8_t c0;
+    const uint8_t *pattern;
+    const uint8_t *entity;
+    int skip;
+} smartypants_subs[] = {
+    { '\'', "'s>",      "&rsquo;",  0 },
+    { '\'', "'t>",      "&rsquo;",  0 },
+    { '\'', "'re>",     "&rsquo;",  0 },
+    { '\'', "'ll>",     "&rsquo;",  0 },
+    { '\'', "'ve>",     "&rsquo;",  0 },
+    { '\'', "'m>",      "&rsquo;",  0 },
+    { '\'', "'d>",      "&rsquo;",  0 },
+    { '-',  "--",       "&mdash;",  1 },
+    { '-',  "<->",      "&ndash;",  0 },
+    { '.',  "...",      "&hellip;", 2 },
+    { '.',  ". . .",    "&hellip;", 4 },
+    { '(',  "(c)",      "&copy;",   2 },
+    { '(',  "(r)",      "&reg;",    2 },
+    { '(',  "(tm)",     "&trade;",  3 },
+    { '3',  "<3/4>",    "&frac34;", 2 },
+    { '3',  "<3/4ths>", "&frac34;", 2 },
+    { '1',  "<1/2>",    "&frac12;", 2 },
+    { '1',  "<1/4>",    "&frac14;", 2 },
+    { '1',  "<1/4th>",  "&frac14;", 2 },
+    { '&',  "&#0;",      0,       3 },
+};
+#endif
+
+void
+sdhtml_smartypants(struct buf *ob, const uint8_t *text, size_t size)
+{
+	size_t i;
+	struct smartypants_data smrt = {0, 0};
+
+	if (!text)
+		return;
+
+	bufgrow(ob, size);
+
+	for (i = 0; i < size; ++i) {
+		size_t org;
+		uint8_t action = 0;
+
+		org = i;
+		while (i < size && (action = smartypants_cb_chars[text[i]]) == 0)
+			i++;
+
+		if (i > org)
+			bufput(ob, text + org, i - org);
+
+		if (i < size) {
+			i += smartypants_cb_ptrs[(int)action]
+				(ob, &smrt, i ? text[i - 1] : 0, text + i, size - i);
+		}
+	}
+}
+
+
diff --git a/src/rt/sundown/html_block_names.txt b/src/rt/sundown/html_block_names.txt
new file mode 100644
index 0000000000000..a41d7d1b33502
--- /dev/null
+++ b/src/rt/sundown/html_block_names.txt
@@ -0,0 +1,25 @@
+##
+p
+dl
+h1
+h2
+h3
+h4
+h5
+h6
+ol
+ul
+del
+div
+ins
+pre
+form
+math
+table
+figure
+iframe
+script
+style
+fieldset
+noscript
+blockquote
diff --git a/src/rt/sundown/src/autolink.c b/src/rt/sundown/src/autolink.c
new file mode 100644
index 0000000000000..6f8d6ab9902b5
--- /dev/null
+++ b/src/rt/sundown/src/autolink.c
@@ -0,0 +1,297 @@
+/*
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "buffer.h"
+#include "autolink.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#if defined(_WIN32)
+#define strncasecmp	_strnicmp
+#endif
+
+int
+sd_autolink_issafe(const uint8_t *link, size_t link_len)
+{
+	static const size_t valid_uris_count = 5;
+	static const char *valid_uris[] = {
+		"/", "http://", "https://", "ftp://", "mailto:"
+	};
+
+	size_t i;
+
+	for (i = 0; i < valid_uris_count; ++i) {
+		size_t len = strlen(valid_uris[i]);
+
+		if (link_len > len &&
+			strncasecmp((char *)link, valid_uris[i], len) == 0 &&
+			isalnum(link[len]))
+			return 1;
+	}
+
+	return 0;
+}
+
+static size_t
+autolink_delim(uint8_t *data, size_t link_end, size_t max_rewind, size_t size)
+{
+	uint8_t cclose, copen = 0;
+	size_t i;
+
+	for (i = 0; i < link_end; ++i)
+		if (data[i] == '<') {
+			link_end = i;
+			break;
+		}
+
+	while (link_end > 0) {
+		if (strchr("?!.,", data[link_end - 1]) != NULL)
+			link_end--;
+
+		else if (data[link_end - 1] == ';') {
+			size_t new_end = link_end - 2;
+
+			while (new_end > 0 && isalpha(data[new_end]))
+				new_end--;
+
+			if (new_end < link_end - 2 && data[new_end] == '&')
+				link_end = new_end;
+			else
+				link_end--;
+		}
+		else break;
+	}
+
+	if (link_end == 0)
+		return 0;
+
+	cclose = data[link_end - 1];
+
+	switch (cclose) {
+	case '"':	copen = '"'; break;
+	case '\'':	copen = '\''; break;
+	case ')':	copen = '('; break;
+	case ']':	copen = '['; break;
+	case '}':	copen = '{'; break;
+	}
+
+	if (copen != 0) {
+		size_t closing = 0;
+		size_t opening = 0;
+		size_t i = 0;
+
+		/* Try to close the final punctuation sign in this same line;
+		 * if we managed to close it outside of the URL, that means that it's
+		 * not part of the URL. If it closes inside the URL, that means it
+		 * is part of the URL.
+		 *
+		 * Examples:
+		 *
+		 *	foo http://www.pokemon.com/Pikachu_(Electric) bar
+		 *		=> http://www.pokemon.com/Pikachu_(Electric)
+		 *
+		 *	foo (http://www.pokemon.com/Pikachu_(Electric)) bar
+		 *		=> http://www.pokemon.com/Pikachu_(Electric)
+		 *
+		 *	foo http://www.pokemon.com/Pikachu_(Electric)) bar
+		 *		=> http://www.pokemon.com/Pikachu_(Electric))
+		 *
+		 *	(foo http://www.pokemon.com/Pikachu_(Electric)) bar
+		 *		=> foo http://www.pokemon.com/Pikachu_(Electric)
+		 */
+
+		while (i < link_end) {
+			if (data[i] == copen)
+				opening++;
+			else if (data[i] == cclose)
+				closing++;
+
+			i++;
+		}
+
+		if (closing != opening)
+			link_end--;
+	}
+
+	return link_end;
+}
+
+static size_t
+check_domain(uint8_t *data, size_t size, int allow_short)
+{
+	size_t i, np = 0;
+
+	if (!isalnum(data[0]))
+		return 0;
+
+	for (i = 1; i < size - 1; ++i) {
+		if (data[i] == '.') np++;
+		else if (!isalnum(data[i]) && data[i] != '-') break;
+	}
+
+	if (allow_short) {
+		/* We don't need a valid domain in the strict sense (with
+		 * least one dot; so just make sure it's composed of valid
+		 * domain characters and return the length of the the valid
+		 * sequence. */
+		return i;
+	} else {
+		/* a valid domain needs to have at least a dot.
+		 * that's as far as we get */
+		return np ? i : 0;
+	}
+}
+
+size_t
+sd_autolink__www(
+	size_t *rewind_p,
+	struct buf *link,
+	uint8_t *data,
+	size_t max_rewind,
+	size_t size,
+	unsigned int flags)
+{
+	size_t link_end;
+
+	if (max_rewind > 0 && !ispunct(data[-1]) && !isspace(data[-1]))
+		return 0;
+
+	if (size < 4 || memcmp(data, "www.", strlen("www.")) != 0)
+		return 0;
+
+	link_end = check_domain(data, size, 0);
+
+	if (link_end == 0)
+		return 0;
+
+	while (link_end < size && !isspace(data[link_end]))
+		link_end++;
+
+	link_end = autolink_delim(data, link_end, max_rewind, size);
+
+	if (link_end == 0)
+		return 0;
+
+	bufput(link, data, link_end);
+	*rewind_p = 0;
+
+	return (int)link_end;
+}
+
+size_t
+sd_autolink__email(
+	size_t *rewind_p,
+	struct buf *link,
+	uint8_t *data,
+	size_t max_rewind,
+	size_t size,
+	unsigned int flags)
+{
+	size_t link_end, rewind;
+	int nb = 0, np = 0;
+
+	for (rewind = 0; rewind < max_rewind; ++rewind) {
+		uint8_t c = data[-rewind - 1];
+
+		if (isalnum(c))
+			continue;
+
+		if (strchr(".+-_", c) != NULL)
+			continue;
+
+		break;
+	}
+
+	if (rewind == 0)
+		return 0;
+
+	for (link_end = 0; link_end < size; ++link_end) {
+		uint8_t c = data[link_end];
+
+		if (isalnum(c))
+			continue;
+
+		if (c == '@')
+			nb++;
+		else if (c == '.' && link_end < size - 1)
+			np++;
+		else if (c != '-' && c != '_')
+			break;
+	}
+
+	if (link_end < 2 || nb != 1 || np == 0 ||
+		!isalpha(data[link_end - 1]))
+		return 0;
+
+	link_end = autolink_delim(data, link_end, max_rewind, size);
+
+	if (link_end == 0)
+		return 0;
+
+	bufput(link, data - rewind, link_end + rewind);
+	*rewind_p = rewind;
+
+	return link_end;
+}
+
+size_t
+sd_autolink__url(
+	size_t *rewind_p,
+	struct buf *link,
+	uint8_t *data,
+	size_t max_rewind,
+	size_t size,
+	unsigned int flags)
+{
+	size_t link_end, rewind = 0, domain_len;
+
+	if (size < 4 || data[1] != '/' || data[2] != '/')
+		return 0;
+
+	while (rewind < max_rewind && isalpha(data[-rewind - 1]))
+		rewind++;
+
+	if (!sd_autolink_issafe(data - rewind, size + rewind))
+		return 0;
+
+	link_end = strlen("://");
+
+	domain_len = check_domain(
+		data + link_end,
+		size - link_end,
+		flags & SD_AUTOLINK_SHORT_DOMAINS);
+
+	if (domain_len == 0)
+		return 0;
+
+	link_end += domain_len;
+	while (link_end < size && !isspace(data[link_end]))
+		link_end++;
+
+	link_end = autolink_delim(data, link_end, max_rewind, size);
+
+	if (link_end == 0)
+		return 0;
+
+	bufput(link, data - rewind, link_end + rewind);
+	*rewind_p = rewind;
+
+	return link_end;
+}
+
diff --git a/src/rt/sundown/src/autolink.h b/src/rt/sundown/src/autolink.h
new file mode 100644
index 0000000000000..65e0fe6f14489
--- /dev/null
+++ b/src/rt/sundown/src/autolink.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef UPSKIRT_AUTOLINK_H
+#define UPSKIRT_AUTOLINK_H
+
+#include "buffer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum {
+	SD_AUTOLINK_SHORT_DOMAINS = (1 << 0),
+};
+
+int
+sd_autolink_issafe(const uint8_t *link, size_t link_len);
+
+size_t
+sd_autolink__www(size_t *rewind_p, struct buf *link,
+	uint8_t *data, size_t offset, size_t size, unsigned int flags);
+
+size_t
+sd_autolink__email(size_t *rewind_p, struct buf *link,
+	uint8_t *data, size_t offset, size_t size, unsigned int flags);
+
+size_t
+sd_autolink__url(size_t *rewind_p, struct buf *link,
+	uint8_t *data, size_t offset, size_t size, unsigned int flags);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/* vim: set filetype=c: */
diff --git a/src/rt/sundown/src/buffer.c b/src/rt/sundown/src/buffer.c
new file mode 100644
index 0000000000000..47b40ce2f75e7
--- /dev/null
+++ b/src/rt/sundown/src/buffer.c
@@ -0,0 +1,225 @@
+/*
+ * Copyright (c) 2008, Natacha Porté
+ * Copyright (c) 2011, Vicent Martí
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#define BUFFER_MAX_ALLOC_SIZE (1024 * 1024 * 16) //16mb
+
+#include "buffer.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+/* MSVC compat */
+#if defined(_MSC_VER)
+#	define _buf_vsnprintf _vsnprintf
+#else
+#	define _buf_vsnprintf vsnprintf
+#endif
+
+int
+bufprefix(const struct buf *buf, const char *prefix)
+{
+	size_t i;
+	assert(buf && buf->unit);
+
+	for (i = 0; i < buf->size; ++i) {
+		if (prefix[i] == 0)
+			return 0;
+
+		if (buf->data[i] != prefix[i])
+			return buf->data[i] - prefix[i];
+	}
+
+	return 0;
+}
+
+/* bufgrow: increasing the allocated size to the given value */
+int
+bufgrow(struct buf *buf, size_t neosz)
+{
+	size_t neoasz;
+	void *neodata;
+
+	assert(buf && buf->unit);
+
+	if (neosz > BUFFER_MAX_ALLOC_SIZE)
+		return BUF_ENOMEM;
+
+	if (buf->asize >= neosz)
+		return BUF_OK;
+
+	neoasz = buf->asize + buf->unit;
+	while (neoasz < neosz)
+		neoasz += buf->unit;
+
+	neodata = realloc(buf->data, neoasz);
+	if (!neodata)
+		return BUF_ENOMEM;
+
+	buf->data = neodata;
+	buf->asize = neoasz;
+	return BUF_OK;
+}
+
+
+/* bufnew: allocation of a new buffer */
+struct buf *
+bufnew(size_t unit)
+{
+	struct buf *ret;
+	ret = malloc(sizeof (struct buf));
+
+	if (ret) {
+		ret->data = 0;
+		ret->size = ret->asize = 0;
+		ret->unit = unit;
+	}
+	return ret;
+}
+
+/* bufnullterm: NULL-termination of the string array */
+const char *
+bufcstr(struct buf *buf)
+{
+	assert(buf && buf->unit);
+
+	if (buf->size < buf->asize && buf->data[buf->size] == 0)
+		return (char *)buf->data;
+
+	if (buf->size + 1 <= buf->asize || bufgrow(buf, buf->size + 1) == 0) {
+		buf->data[buf->size] = 0;
+		return (char *)buf->data;
+	}
+
+	return NULL;
+}
+
+/* bufprintf: formatted printing to a buffer */
+void
+bufprintf(struct buf *buf, const char *fmt, ...)
+{
+	va_list ap;
+	int n;
+
+	assert(buf && buf->unit);
+
+	if (buf->size >= buf->asize && bufgrow(buf, buf->size + 1) < 0)
+		return;
+	
+	va_start(ap, fmt);
+	n = _buf_vsnprintf((char *)buf->data + buf->size, buf->asize - buf->size, fmt, ap);
+	va_end(ap);
+
+	if (n < 0) {
+#ifdef _MSC_VER
+		va_start(ap, fmt);
+		n = _vscprintf(fmt, ap);
+		va_end(ap);
+#else
+		return;
+#endif
+	}
+
+	if ((size_t)n >= buf->asize - buf->size) {
+		if (bufgrow(buf, buf->size + n + 1) < 0)
+			return;
+
+		va_start(ap, fmt);
+		n = _buf_vsnprintf((char *)buf->data + buf->size, buf->asize - buf->size, fmt, ap);
+		va_end(ap);
+	}
+
+	if (n < 0)
+		return;
+
+	buf->size += n;
+}
+
+/* bufput: appends raw data to a buffer */
+void
+bufput(struct buf *buf, const void *data, size_t len)
+{
+	assert(buf && buf->unit);
+
+	if (buf->size + len > buf->asize && bufgrow(buf, buf->size + len) < 0)
+		return;
+
+	memcpy(buf->data + buf->size, data, len);
+	buf->size += len;
+}
+
+/* bufputs: appends a NUL-terminated string to a buffer */
+void
+bufputs(struct buf *buf, const char *str)
+{
+	bufput(buf, str, strlen(str));
+}
+
+
+/* bufputc: appends a single uint8_t to a buffer */
+void
+bufputc(struct buf *buf, int c)
+{
+	assert(buf && buf->unit);
+
+	if (buf->size + 1 > buf->asize && bufgrow(buf, buf->size + 1) < 0)
+		return;
+
+	buf->data[buf->size] = c;
+	buf->size += 1;
+}
+
+/* bufrelease: decrease the reference count and free the buffer if needed */
+void
+bufrelease(struct buf *buf)
+{
+	if (!buf)
+		return;
+
+	free(buf->data);
+	free(buf);
+}
+
+
+/* bufreset: frees internal data of the buffer */
+void
+bufreset(struct buf *buf)
+{
+	if (!buf)
+		return;
+
+	free(buf->data);
+	buf->data = NULL;
+	buf->size = buf->asize = 0;
+}
+
+/* bufslurp: removes a given number of bytes from the head of the array */
+void
+bufslurp(struct buf *buf, size_t len)
+{
+	assert(buf && buf->unit);
+
+	if (len >= buf->size) {
+		buf->size = 0;
+		return;
+	}
+
+	buf->size -= len;
+	memmove(buf->data, buf->data + len, buf->size);
+}
+
diff --git a/src/rt/sundown/src/buffer.h b/src/rt/sundown/src/buffer.h
new file mode 100644
index 0000000000000..221d142eda337
--- /dev/null
+++ b/src/rt/sundown/src/buffer.h
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2008, Natacha Porté
+ * Copyright (c) 2011, Vicent Martí
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef BUFFER_H__
+#define BUFFER_H__
+
+#include <stddef.h>
+#include <stdarg.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if defined(_MSC_VER)
+#define __attribute__(x)
+#define inline
+#endif
+
+typedef enum {
+	BUF_OK = 0,
+	BUF_ENOMEM = -1,
+} buferror_t;
+
+/* struct buf: character array buffer */
+struct buf {
+	uint8_t *data;		/* actual character data */
+	size_t size;	/* size of the string */
+	size_t asize;	/* allocated size (0 = volatile buffer) */
+	size_t unit;	/* reallocation unit size (0 = read-only buffer) */
+};
+
+/* CONST_BUF: global buffer from a string litteral */
+#define BUF_STATIC(string) \
+	{ (uint8_t *)string, sizeof string -1, sizeof string, 0, 0 }
+
+/* VOLATILE_BUF: macro for creating a volatile buffer on the stack */
+#define BUF_VOLATILE(strname) \
+	{ (uint8_t *)strname, strlen(strname), 0, 0, 0 }
+
+/* BUFPUTSL: optimized bufputs of a string litteral */
+#define BUFPUTSL(output, literal) \
+	bufput(output, literal, sizeof literal - 1)
+
+/* bufgrow: increasing the allocated size to the given value */
+int bufgrow(struct buf *, size_t);
+
+/* bufnew: allocation of a new buffer */
+struct buf *bufnew(size_t) __attribute__ ((malloc));
+
+/* bufnullterm: NUL-termination of the string array (making a C-string) */
+const char *bufcstr(struct buf *);
+
+/* bufprefix: compare the beginning of a buffer with a string */
+int bufprefix(const struct buf *buf, const char *prefix);
+
+/* bufput: appends raw data to a buffer */
+void bufput(struct buf *, const void *, size_t);
+
+/* bufputs: appends a NUL-terminated string to a buffer */
+void bufputs(struct buf *, const char *);
+
+/* bufputc: appends a single char to a buffer */
+void bufputc(struct buf *, int);
+
+/* bufrelease: decrease the reference count and free the buffer if needed */
+void bufrelease(struct buf *);
+
+/* bufreset: frees internal data of the buffer */
+void bufreset(struct buf *);
+
+/* bufslurp: removes a given number of bytes from the head of the array */
+void bufslurp(struct buf *, size_t);
+
+/* bufprintf: formatted printing to a buffer */
+void bufprintf(struct buf *, const char *, ...) __attribute__ ((format (printf, 2, 3)));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/rt/sundown/src/html_blocks.h b/src/rt/sundown/src/html_blocks.h
new file mode 100644
index 0000000000000..09a758fe275f7
--- /dev/null
+++ b/src/rt/sundown/src/html_blocks.h
@@ -0,0 +1,206 @@
+/* C code produced by gperf version 3.0.3 */
+/* Command-line: gperf -N find_block_tag -H hash_block_tag -C -c -E --ignore-case html_block_names.txt  */
+/* Computed positions: -k'1-2' */
+
+#if !((' ' == 32) && ('!' == 33) && ('"' == 34) && ('#' == 35) \
+      && ('%' == 37) && ('&' == 38) && ('\'' == 39) && ('(' == 40) \
+      && (')' == 41) && ('*' == 42) && ('+' == 43) && (',' == 44) \
+      && ('-' == 45) && ('.' == 46) && ('/' == 47) && ('0' == 48) \
+      && ('1' == 49) && ('2' == 50) && ('3' == 51) && ('4' == 52) \
+      && ('5' == 53) && ('6' == 54) && ('7' == 55) && ('8' == 56) \
+      && ('9' == 57) && (':' == 58) && (';' == 59) && ('<' == 60) \
+      && ('=' == 61) && ('>' == 62) && ('?' == 63) && ('A' == 65) \
+      && ('B' == 66) && ('C' == 67) && ('D' == 68) && ('E' == 69) \
+      && ('F' == 70) && ('G' == 71) && ('H' == 72) && ('I' == 73) \
+      && ('J' == 74) && ('K' == 75) && ('L' == 76) && ('M' == 77) \
+      && ('N' == 78) && ('O' == 79) && ('P' == 80) && ('Q' == 81) \
+      && ('R' == 82) && ('S' == 83) && ('T' == 84) && ('U' == 85) \
+      && ('V' == 86) && ('W' == 87) && ('X' == 88) && ('Y' == 89) \
+      && ('Z' == 90) && ('[' == 91) && ('\\' == 92) && (']' == 93) \
+      && ('^' == 94) && ('_' == 95) && ('a' == 97) && ('b' == 98) \
+      && ('c' == 99) && ('d' == 100) && ('e' == 101) && ('f' == 102) \
+      && ('g' == 103) && ('h' == 104) && ('i' == 105) && ('j' == 106) \
+      && ('k' == 107) && ('l' == 108) && ('m' == 109) && ('n' == 110) \
+      && ('o' == 111) && ('p' == 112) && ('q' == 113) && ('r' == 114) \
+      && ('s' == 115) && ('t' == 116) && ('u' == 117) && ('v' == 118) \
+      && ('w' == 119) && ('x' == 120) && ('y' == 121) && ('z' == 122) \
+      && ('{' == 123) && ('|' == 124) && ('}' == 125) && ('~' == 126))
+/* The character set is not based on ISO-646.  */
+error "gperf generated tables don't work with this execution character set. Please report a bug to <bug-gnu-gperf@gnu.org>."
+#endif
+
+/* maximum key range = 37, duplicates = 0 */
+
+#ifndef GPERF_DOWNCASE
+#define GPERF_DOWNCASE 1
+static unsigned char gperf_downcase[256] =
+  {
+      0,   1,   2,   3,   4,   5,   6,   7,   8,   9,  10,  11,  12,  13,  14,
+     15,  16,  17,  18,  19,  20,  21,  22,  23,  24,  25,  26,  27,  28,  29,
+     30,  31,  32,  33,  34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,
+     45,  46,  47,  48,  49,  50,  51,  52,  53,  54,  55,  56,  57,  58,  59,
+     60,  61,  62,  63,  64,  97,  98,  99, 100, 101, 102, 103, 104, 105, 106,
+    107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
+    122,  91,  92,  93,  94,  95,  96,  97,  98,  99, 100, 101, 102, 103, 104,
+    105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119,
+    120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134,
+    135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149,
+    150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164,
+    165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179,
+    180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194,
+    195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209,
+    210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224,
+    225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
+    240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254,
+    255
+  };
+#endif
+
+#ifndef GPERF_CASE_STRNCMP
+#define GPERF_CASE_STRNCMP 1
+static int
+gperf_case_strncmp (s1, s2, n)
+     register const char *s1;
+     register const char *s2;
+     register unsigned int n;
+{
+  for (; n > 0;)
+    {
+      unsigned char c1 = gperf_downcase[(unsigned char)*s1++];
+      unsigned char c2 = gperf_downcase[(unsigned char)*s2++];
+      if (c1 != 0 && c1 == c2)
+        {
+          n--;
+          continue;
+        }
+      return (int)c1 - (int)c2;
+    }
+  return 0;
+}
+#endif
+
+#ifdef __GNUC__
+__inline
+#else
+#ifdef __cplusplus
+inline
+#endif
+#endif
+static unsigned int
+hash_block_tag (str, len)
+     register const char *str;
+     register unsigned int len;
+{
+  static const unsigned char asso_values[] =
+    {
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+       8, 30, 25, 20, 15, 10, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38,  0, 38,  0, 38,
+       5,  5,  5, 15,  0, 38, 38,  0, 15, 10,
+       0, 38, 38, 15,  0,  5, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38,  0, 38,
+       0, 38,  5,  5,  5, 15,  0, 38, 38,  0,
+      15, 10,  0, 38, 38, 15,  0,  5, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38, 38, 38, 38,
+      38, 38, 38, 38, 38, 38, 38
+    };
+  register int hval = len;
+
+  switch (hval)
+    {
+      default:
+        hval += asso_values[(unsigned char)str[1]+1];
+      /*FALLTHROUGH*/
+      case 1:
+        hval += asso_values[(unsigned char)str[0]];
+        break;
+    }
+  return hval;
+}
+
+#ifdef __GNUC__
+__inline
+#ifdef __GNUC_STDC_INLINE__
+__attribute__ ((__gnu_inline__))
+#endif
+#endif
+const char *
+find_block_tag (str, len)
+     register const char *str;
+     register unsigned int len;
+{
+  enum
+    {
+      TOTAL_KEYWORDS = 24,
+      MIN_WORD_LENGTH = 1,
+      MAX_WORD_LENGTH = 10,
+      MIN_HASH_VALUE = 1,
+      MAX_HASH_VALUE = 37
+    };
+
+  static const char * const wordlist[] =
+    {
+      "",
+      "p",
+      "dl",
+      "div",
+      "math",
+      "table",
+      "",
+      "ul",
+      "del",
+      "form",
+      "blockquote",
+      "figure",
+      "ol",
+      "fieldset",
+      "",
+      "h1",
+      "",
+      "h6",
+      "pre",
+      "", "",
+      "script",
+      "h5",
+      "noscript",
+      "",
+      "style",
+      "iframe",
+      "h4",
+      "ins",
+      "", "", "",
+      "h3",
+      "", "", "", "",
+      "h2"
+    };
+
+  if (len <= MAX_WORD_LENGTH && len >= MIN_WORD_LENGTH)
+    {
+      register int key = hash_block_tag (str, len);
+
+      if (key <= MAX_HASH_VALUE && key >= 0)
+        {
+          register const char *s = wordlist[key];
+
+          if ((((unsigned char)*str ^ (unsigned char)*s) & ~32) == 0 && !gperf_case_strncmp (str, s, len) && s[len] == '\0')
+            return s;
+        }
+    }
+  return 0;
+}
diff --git a/src/rt/sundown/src/markdown.c b/src/rt/sundown/src/markdown.c
new file mode 100644
index 0000000000000..ea3cf23253ad3
--- /dev/null
+++ b/src/rt/sundown/src/markdown.c
@@ -0,0 +1,2556 @@
+/* markdown.c - generic markdown parser */
+
+/*
+ * Copyright (c) 2009, Natacha Porté
+ * Copyright (c) 2011, Vicent Marti
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "markdown.h"
+#include "stack.h"
+
+#include <assert.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdio.h>
+
+#if defined(_WIN32)
+#define strncasecmp	_strnicmp
+#endif
+
+#define REF_TABLE_SIZE 8
+
+#define BUFFER_BLOCK 0
+#define BUFFER_SPAN 1
+
+#define MKD_LI_END 8	/* internal list flag */
+
+#define gperf_case_strncmp(s1, s2, n) strncasecmp(s1, s2, n)
+#define GPERF_DOWNCASE 1
+#define GPERF_CASE_STRNCMP 1
+#include "html_blocks.h"
+
+/***************
+ * LOCAL TYPES *
+ ***************/
+
+/* link_ref: reference to a link */
+struct link_ref {
+	unsigned int id;
+
+	struct buf *link;
+	struct buf *title;
+
+	struct link_ref *next;
+};
+
+/* char_trigger: function pointer to render active chars */
+/*   returns the number of chars taken care of */
+/*   data is the pointer of the beginning of the span */
+/*   offset is the number of valid chars before data */
+struct sd_markdown;
+typedef size_t
+(*char_trigger)(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+
+static size_t char_emphasis(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_linebreak(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_codespan(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_escape(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_entity(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_langle_tag(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_autolink_url(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_autolink_email(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_autolink_www(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_link(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+static size_t char_superscript(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size);
+
+enum markdown_char_t {
+	MD_CHAR_NONE = 0,
+	MD_CHAR_EMPHASIS,
+	MD_CHAR_CODESPAN,
+	MD_CHAR_LINEBREAK,
+	MD_CHAR_LINK,
+	MD_CHAR_LANGLE,
+	MD_CHAR_ESCAPE,
+	MD_CHAR_ENTITITY,
+	MD_CHAR_AUTOLINK_URL,
+	MD_CHAR_AUTOLINK_EMAIL,
+	MD_CHAR_AUTOLINK_WWW,
+	MD_CHAR_SUPERSCRIPT,
+};
+
+static char_trigger markdown_char_ptrs[] = {
+	NULL,
+	&char_emphasis,
+	&char_codespan,
+	&char_linebreak,
+	&char_link,
+	&char_langle_tag,
+	&char_escape,
+	&char_entity,
+	&char_autolink_url,
+	&char_autolink_email,
+	&char_autolink_www,
+	&char_superscript,
+};
+
+/* render • structure containing one particular render */
+struct sd_markdown {
+	struct sd_callbacks	cb;
+	void *opaque;
+
+	struct link_ref *refs[REF_TABLE_SIZE];
+	uint8_t active_char[256];
+	struct stack work_bufs[2];
+	unsigned int ext_flags;
+	size_t max_nesting;
+	int in_link_body;
+};
+
+/***************************
+ * HELPER FUNCTIONS *
+ ***************************/
+
+static inline struct buf *
+rndr_newbuf(struct sd_markdown *rndr, int type)
+{
+	static const size_t buf_size[2] = {256, 64};
+	struct buf *work = NULL;
+	struct stack *pool = &rndr->work_bufs[type];
+
+	if (pool->size < pool->asize &&
+		pool->item[pool->size] != NULL) {
+		work = pool->item[pool->size++];
+		work->size = 0;
+	} else {
+		work = bufnew(buf_size[type]);
+		stack_push(pool, work);
+	}
+
+	return work;
+}
+
+static inline void
+rndr_popbuf(struct sd_markdown *rndr, int type)
+{
+	rndr->work_bufs[type].size--;
+}
+
+static void
+unscape_text(struct buf *ob, struct buf *src)
+{
+	size_t i = 0, org;
+	while (i < src->size) {
+		org = i;
+		while (i < src->size && src->data[i] != '\\')
+			i++;
+
+		if (i > org)
+			bufput(ob, src->data + org, i - org);
+
+		if (i + 1 >= src->size)
+			break;
+
+		bufputc(ob, src->data[i + 1]);
+		i += 2;
+	}
+}
+
+static unsigned int
+hash_link_ref(const uint8_t *link_ref, size_t length)
+{
+	size_t i;
+	unsigned int hash = 0;
+
+	for (i = 0; i < length; ++i)
+		hash = tolower(link_ref[i]) + (hash << 6) + (hash << 16) - hash;
+
+	return hash;
+}
+
+static struct link_ref *
+add_link_ref(
+	struct link_ref **references,
+	const uint8_t *name, size_t name_size)
+{
+	struct link_ref *ref = calloc(1, sizeof(struct link_ref));
+
+	if (!ref)
+		return NULL;
+
+	ref->id = hash_link_ref(name, name_size);
+	ref->next = references[ref->id % REF_TABLE_SIZE];
+
+	references[ref->id % REF_TABLE_SIZE] = ref;
+	return ref;
+}
+
+static struct link_ref *
+find_link_ref(struct link_ref **references, uint8_t *name, size_t length)
+{
+	unsigned int hash = hash_link_ref(name, length);
+	struct link_ref *ref = NULL;
+
+	ref = references[hash % REF_TABLE_SIZE];
+
+	while (ref != NULL) {
+		if (ref->id == hash)
+			return ref;
+
+		ref = ref->next;
+	}
+
+	return NULL;
+}
+
+static void
+free_link_refs(struct link_ref **references)
+{
+	size_t i;
+
+	for (i = 0; i < REF_TABLE_SIZE; ++i) {
+		struct link_ref *r = references[i];
+		struct link_ref *next;
+
+		while (r) {
+			next = r->next;
+			bufrelease(r->link);
+			bufrelease(r->title);
+			free(r);
+			r = next;
+		}
+	}
+}
+
+/*
+ * Check whether a char is a Markdown space.
+
+ * Right now we only consider spaces the actual
+ * space and a newline: tabs and carriage returns
+ * are filtered out during the preprocessing phase.
+ *
+ * If we wanted to actually be UTF-8 compliant, we
+ * should instead extract an Unicode codepoint from
+ * this character and check for space properties.
+ */
+static inline int
+_isspace(int c)
+{
+	return c == ' ' || c == '\n';
+}
+
+/****************************
+ * INLINE PARSING FUNCTIONS *
+ ****************************/
+
+/* is_mail_autolink • looks for the address part of a mail autolink and '>' */
+/* this is less strict than the original markdown e-mail address matching */
+static size_t
+is_mail_autolink(uint8_t *data, size_t size)
+{
+	size_t i = 0, nb = 0;
+
+	/* address is assumed to be: [-@._a-zA-Z0-9]+ with exactly one '@' */
+	for (i = 0; i < size; ++i) {
+		if (isalnum(data[i]))
+			continue;
+
+		switch (data[i]) {
+			case '@':
+				nb++;
+
+			case '-':
+			case '.':
+			case '_':
+				break;
+
+			case '>':
+				return (nb == 1) ? i + 1 : 0;
+
+			default:
+				return 0;
+		}
+	}
+
+	return 0;
+}
+
+/* tag_length • returns the length of the given tag, or 0 is it's not valid */
+static size_t
+tag_length(uint8_t *data, size_t size, enum mkd_autolink *autolink)
+{
+	size_t i, j;
+
+	/* a valid tag can't be shorter than 3 chars */
+	if (size < 3) return 0;
+
+	/* begins with a '<' optionally followed by '/', followed by letter or number */
+	if (data[0] != '<') return 0;
+	i = (data[1] == '/') ? 2 : 1;
+
+	if (!isalnum(data[i]))
+		return 0;
+
+	/* scheme test */
+	*autolink = MKDA_NOT_AUTOLINK;
+
+	/* try to find the beginning of an URI */
+	while (i < size && (isalnum(data[i]) || data[i] == '.' || data[i] == '+' || data[i] == '-'))
+		i++;
+
+	if (i > 1 && data[i] == '@') {
+		if ((j = is_mail_autolink(data + i, size - i)) != 0) {
+			*autolink = MKDA_EMAIL;
+			return i + j;
+		}
+	}
+
+	if (i > 2 && data[i] == ':') {
+		*autolink = MKDA_NORMAL;
+		i++;
+	}
+
+	/* completing autolink test: no whitespace or ' or " */
+	if (i >= size)
+		*autolink = MKDA_NOT_AUTOLINK;
+
+	else if (*autolink) {
+		j = i;
+
+		while (i < size) {
+			if (data[i] == '\\') i += 2;
+			else if (data[i] == '>' || data[i] == '\'' ||
+					data[i] == '"' || data[i] == ' ' || data[i] == '\n')
+					break;
+			else i++;
+		}
+
+		if (i >= size) return 0;
+		if (i > j && data[i] == '>') return i + 1;
+		/* one of the forbidden chars has been found */
+		*autolink = MKDA_NOT_AUTOLINK;
+	}
+
+	/* looking for sometinhg looking like a tag end */
+	while (i < size && data[i] != '>') i++;
+	if (i >= size) return 0;
+	return i + 1;
+}
+
+/* parse_inline • parses inline markdown elements */
+static void
+parse_inline(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t i = 0, end = 0;
+	uint8_t action = 0;
+	struct buf work = { 0, 0, 0, 0 };
+
+	if (rndr->work_bufs[BUFFER_SPAN].size +
+		rndr->work_bufs[BUFFER_BLOCK].size > rndr->max_nesting)
+		return;
+
+	while (i < size) {
+		/* copying inactive chars into the output */
+		while (end < size && (action = rndr->active_char[data[end]]) == 0) {
+			end++;
+		}
+
+		if (rndr->cb.normal_text) {
+			work.data = data + i;
+			work.size = end - i;
+			rndr->cb.normal_text(ob, &work, rndr->opaque);
+		}
+		else
+			bufput(ob, data + i, end - i);
+
+		if (end >= size) break;
+		i = end;
+
+		end = markdown_char_ptrs[(int)action](ob, rndr, data + i, i, size - i);
+		if (!end) /* no action from the callback */
+			end = i + 1;
+		else {
+			i += end;
+			end = i;
+		}
+	}
+}
+
+/* find_emph_char • looks for the next emph uint8_t, skipping other constructs */
+static size_t
+find_emph_char(uint8_t *data, size_t size, uint8_t c)
+{
+	size_t i = 1;
+
+	while (i < size) {
+		while (i < size && data[i] != c && data[i] != '`' && data[i] != '[')
+			i++;
+
+		if (i == size)
+			return 0;
+
+		if (data[i] == c)
+			return i;
+
+		/* not counting escaped chars */
+		if (i && data[i - 1] == '\\') {
+			i++; continue;
+		}
+
+		if (data[i] == '`') {
+			size_t span_nb = 0, bt;
+			size_t tmp_i = 0;
+
+			/* counting the number of opening backticks */
+			while (i < size && data[i] == '`') {
+				i++; span_nb++;
+			}
+
+			if (i >= size) return 0;
+
+			/* finding the matching closing sequence */
+			bt = 0;
+			while (i < size && bt < span_nb) {
+				if (!tmp_i && data[i] == c) tmp_i = i;
+				if (data[i] == '`') bt++;
+				else bt = 0;
+				i++;
+			}
+
+			if (i >= size) return tmp_i;
+		}
+		/* skipping a link */
+		else if (data[i] == '[') {
+			size_t tmp_i = 0;
+			uint8_t cc;
+
+			i++;
+			while (i < size && data[i] != ']') {
+				if (!tmp_i && data[i] == c) tmp_i = i;
+				i++;
+			}
+
+			i++;
+			while (i < size && (data[i] == ' ' || data[i] == '\n'))
+				i++;
+
+			if (i >= size)
+				return tmp_i;
+
+			switch (data[i]) {
+			case '[':
+				cc = ']'; break;
+
+			case '(':
+				cc = ')'; break;
+
+			default:
+				if (tmp_i)
+					return tmp_i;
+				else
+					continue;
+			}
+
+			i++;
+			while (i < size && data[i] != cc) {
+				if (!tmp_i && data[i] == c) tmp_i = i;
+				i++;
+			}
+
+			if (i >= size)
+				return tmp_i;
+
+			i++;
+		}
+	}
+
+	return 0;
+}
+
+/* parse_emph1 • parsing single emphase */
+/* closed by a symbol not preceded by whitespace and not followed by symbol */
+static size_t
+parse_emph1(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, uint8_t c)
+{
+	size_t i = 0, len;
+	struct buf *work = 0;
+	int r;
+
+	if (!rndr->cb.emphasis) return 0;
+
+	/* skipping one symbol if coming from emph3 */
+	if (size > 1 && data[0] == c && data[1] == c) i = 1;
+
+	while (i < size) {
+		len = find_emph_char(data + i, size - i, c);
+		if (!len) return 0;
+		i += len;
+		if (i >= size) return 0;
+
+		if (data[i] == c && !_isspace(data[i - 1])) {
+
+			if (rndr->ext_flags & MKDEXT_NO_INTRA_EMPHASIS) {
+				if (i + 1 < size && isalnum(data[i + 1]))
+					continue;
+			}
+
+			work = rndr_newbuf(rndr, BUFFER_SPAN);
+			parse_inline(work, rndr, data, i);
+			r = rndr->cb.emphasis(ob, work, rndr->opaque);
+			rndr_popbuf(rndr, BUFFER_SPAN);
+			return r ? i + 1 : 0;
+		}
+	}
+
+	return 0;
+}
+
+/* parse_emph2 • parsing single emphase */
+static size_t
+parse_emph2(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, uint8_t c)
+{
+	int (*render_method)(struct buf *ob, const struct buf *text, void *opaque);
+	size_t i = 0, len;
+	struct buf *work = 0;
+	int r;
+
+	render_method = (c == '~') ? rndr->cb.strikethrough : rndr->cb.double_emphasis;
+
+	if (!render_method)
+		return 0;
+
+	while (i < size) {
+		len = find_emph_char(data + i, size - i, c);
+		if (!len) return 0;
+		i += len;
+
+		if (i + 1 < size && data[i] == c && data[i + 1] == c && i && !_isspace(data[i - 1])) {
+			work = rndr_newbuf(rndr, BUFFER_SPAN);
+			parse_inline(work, rndr, data, i);
+			r = render_method(ob, work, rndr->opaque);
+			rndr_popbuf(rndr, BUFFER_SPAN);
+			return r ? i + 2 : 0;
+		}
+		i++;
+	}
+	return 0;
+}
+
+/* parse_emph3 • parsing single emphase */
+/* finds the first closing tag, and delegates to the other emph */
+static size_t
+parse_emph3(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, uint8_t c)
+{
+	size_t i = 0, len;
+	int r;
+
+	while (i < size) {
+		len = find_emph_char(data + i, size - i, c);
+		if (!len) return 0;
+		i += len;
+
+		/* skip whitespace preceded symbols */
+		if (data[i] != c || _isspace(data[i - 1]))
+			continue;
+
+		if (i + 2 < size && data[i + 1] == c && data[i + 2] == c && rndr->cb.triple_emphasis) {
+			/* triple symbol found */
+			struct buf *work = rndr_newbuf(rndr, BUFFER_SPAN);
+
+			parse_inline(work, rndr, data, i);
+			r = rndr->cb.triple_emphasis(ob, work, rndr->opaque);
+			rndr_popbuf(rndr, BUFFER_SPAN);
+			return r ? i + 3 : 0;
+
+		} else if (i + 1 < size && data[i + 1] == c) {
+			/* double symbol found, handing over to emph1 */
+			len = parse_emph1(ob, rndr, data - 2, size + 2, c);
+			if (!len) return 0;
+			else return len - 2;
+
+		} else {
+			/* single symbol found, handing over to emph2 */
+			len = parse_emph2(ob, rndr, data - 1, size + 1, c);
+			if (!len) return 0;
+			else return len - 1;
+		}
+	}
+	return 0;
+}
+
+/* char_emphasis • single and double emphasis parsing */
+static size_t
+char_emphasis(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	uint8_t c = data[0];
+	size_t ret;
+
+	if (rndr->ext_flags & MKDEXT_NO_INTRA_EMPHASIS) {
+		if (offset > 0 && !_isspace(data[-1]) && data[-1] != '>')
+			return 0;
+	}
+
+	if (size > 2 && data[1] != c) {
+		/* whitespace cannot follow an opening emphasis;
+		 * strikethrough only takes two characters '~~' */
+		if (c == '~' || _isspace(data[1]) || (ret = parse_emph1(ob, rndr, data + 1, size - 1, c)) == 0)
+			return 0;
+
+		return ret + 1;
+	}
+
+	if (size > 3 && data[1] == c && data[2] != c) {
+		if (_isspace(data[2]) || (ret = parse_emph2(ob, rndr, data + 2, size - 2, c)) == 0)
+			return 0;
+
+		return ret + 2;
+	}
+
+	if (size > 4 && data[1] == c && data[2] == c && data[3] != c) {
+		if (c == '~' || _isspace(data[3]) || (ret = parse_emph3(ob, rndr, data + 3, size - 3, c)) == 0)
+			return 0;
+
+		return ret + 3;
+	}
+
+	return 0;
+}
+
+
+/* char_linebreak • '\n' preceded by two spaces (assuming linebreak != 0) */
+static size_t
+char_linebreak(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	if (offset < 2 || data[-1] != ' ' || data[-2] != ' ')
+		return 0;
+
+	/* removing the last space from ob and rendering */
+	while (ob->size && ob->data[ob->size - 1] == ' ')
+		ob->size--;
+
+	return rndr->cb.linebreak(ob, rndr->opaque) ? 1 : 0;
+}
+
+
+/* char_codespan • '`' parsing a code span (assuming codespan != 0) */
+static size_t
+char_codespan(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	size_t end, nb = 0, i, f_begin, f_end;
+
+	/* counting the number of backticks in the delimiter */
+	while (nb < size && data[nb] == '`')
+		nb++;
+
+	/* finding the next delimiter */
+	i = 0;
+	for (end = nb; end < size && i < nb; end++) {
+		if (data[end] == '`') i++;
+		else i = 0;
+	}
+
+	if (i < nb && end >= size)
+		return 0; /* no matching delimiter */
+
+	/* trimming outside whitespaces */
+	f_begin = nb;
+	while (f_begin < end && data[f_begin] == ' ')
+		f_begin++;
+
+	f_end = end - nb;
+	while (f_end > nb && data[f_end-1] == ' ')
+		f_end--;
+
+	/* real code span */
+	if (f_begin < f_end) {
+		struct buf work = { data + f_begin, f_end - f_begin, 0, 0 };
+		if (!rndr->cb.codespan(ob, &work, rndr->opaque))
+			end = 0;
+	} else {
+		if (!rndr->cb.codespan(ob, 0, rndr->opaque))
+			end = 0;
+	}
+
+	return end;
+}
+
+
+/* char_escape • '\\' backslash escape */
+static size_t
+char_escape(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	static const char *escape_chars = "\\`*_{}[]()#+-.!:|&<>^~";
+	struct buf work = { 0, 0, 0, 0 };
+
+	if (size > 1) {
+		if (strchr(escape_chars, data[1]) == NULL)
+			return 0;
+
+		if (rndr->cb.normal_text) {
+			work.data = data + 1;
+			work.size = 1;
+			rndr->cb.normal_text(ob, &work, rndr->opaque);
+		}
+		else bufputc(ob, data[1]);
+	} else if (size == 1) {
+		bufputc(ob, data[0]);
+	}
+
+	return 2;
+}
+
+/* char_entity • '&' escaped when it doesn't belong to an entity */
+/* valid entities are assumed to be anything matching &#?[A-Za-z0-9]+; */
+static size_t
+char_entity(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	size_t end = 1;
+	struct buf work = { 0, 0, 0, 0 };
+
+	if (end < size && data[end] == '#')
+		end++;
+
+	while (end < size && isalnum(data[end]))
+		end++;
+
+	if (end < size && data[end] == ';')
+		end++; /* real entity */
+	else
+		return 0; /* lone '&' */
+
+	if (rndr->cb.entity) {
+		work.data = data;
+		work.size = end;
+		rndr->cb.entity(ob, &work, rndr->opaque);
+	}
+	else bufput(ob, data, end);
+
+	return end;
+}
+
+/* char_langle_tag • '<' when tags or autolinks are allowed */
+static size_t
+char_langle_tag(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	enum mkd_autolink altype = MKDA_NOT_AUTOLINK;
+	size_t end = tag_length(data, size, &altype);
+	struct buf work = { data, end, 0, 0 };
+	int ret = 0;
+
+	if (end > 2) {
+		if (rndr->cb.autolink && altype != MKDA_NOT_AUTOLINK) {
+			struct buf *u_link = rndr_newbuf(rndr, BUFFER_SPAN);
+			work.data = data + 1;
+			work.size = end - 2;
+			unscape_text(u_link, &work);
+			ret = rndr->cb.autolink(ob, u_link, altype, rndr->opaque);
+			rndr_popbuf(rndr, BUFFER_SPAN);
+		}
+		else if (rndr->cb.raw_html_tag)
+			ret = rndr->cb.raw_html_tag(ob, &work, rndr->opaque);
+	}
+
+	if (!ret) return 0;
+	else return end;
+}
+
+static size_t
+char_autolink_www(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	struct buf *link, *link_url, *link_text;
+	size_t link_len, rewind;
+
+	if (!rndr->cb.link || rndr->in_link_body)
+		return 0;
+
+	link = rndr_newbuf(rndr, BUFFER_SPAN);
+
+	if ((link_len = sd_autolink__www(&rewind, link, data, offset, size, 0)) > 0) {
+		link_url = rndr_newbuf(rndr, BUFFER_SPAN);
+		BUFPUTSL(link_url, "http://");
+		bufput(link_url, link->data, link->size);
+
+		ob->size -= rewind;
+		if (rndr->cb.normal_text) {
+			link_text = rndr_newbuf(rndr, BUFFER_SPAN);
+			rndr->cb.normal_text(link_text, link, rndr->opaque);
+			rndr->cb.link(ob, link_url, NULL, link_text, rndr->opaque);
+			rndr_popbuf(rndr, BUFFER_SPAN);
+		} else {
+			rndr->cb.link(ob, link_url, NULL, link, rndr->opaque);
+		}
+		rndr_popbuf(rndr, BUFFER_SPAN);
+	}
+
+	rndr_popbuf(rndr, BUFFER_SPAN);
+	return link_len;
+}
+
+static size_t
+char_autolink_email(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	struct buf *link;
+	size_t link_len, rewind;
+
+	if (!rndr->cb.autolink || rndr->in_link_body)
+		return 0;
+
+	link = rndr_newbuf(rndr, BUFFER_SPAN);
+
+	if ((link_len = sd_autolink__email(&rewind, link, data, offset, size, 0)) > 0) {
+		ob->size -= rewind;
+		rndr->cb.autolink(ob, link, MKDA_EMAIL, rndr->opaque);
+	}
+
+	rndr_popbuf(rndr, BUFFER_SPAN);
+	return link_len;
+}
+
+static size_t
+char_autolink_url(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	struct buf *link;
+	size_t link_len, rewind;
+
+	if (!rndr->cb.autolink || rndr->in_link_body)
+		return 0;
+
+	link = rndr_newbuf(rndr, BUFFER_SPAN);
+
+	if ((link_len = sd_autolink__url(&rewind, link, data, offset, size, 0)) > 0) {
+		ob->size -= rewind;
+		rndr->cb.autolink(ob, link, MKDA_NORMAL, rndr->opaque);
+	}
+
+	rndr_popbuf(rndr, BUFFER_SPAN);
+	return link_len;
+}
+
+/* char_link • '[': parsing a link or an image */
+static size_t
+char_link(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	int is_img = (offset && data[-1] == '!'), level;
+	size_t i = 1, txt_e, link_b = 0, link_e = 0, title_b = 0, title_e = 0;
+	struct buf *content = 0;
+	struct buf *link = 0;
+	struct buf *title = 0;
+	struct buf *u_link = 0;
+	size_t org_work_size = rndr->work_bufs[BUFFER_SPAN].size;
+	int text_has_nl = 0, ret = 0;
+	int in_title = 0, qtype = 0;
+
+	/* checking whether the correct renderer exists */
+	if ((is_img && !rndr->cb.image) || (!is_img && !rndr->cb.link))
+		goto cleanup;
+
+	/* looking for the matching closing bracket */
+	for (level = 1; i < size; i++) {
+		if (data[i] == '\n')
+			text_has_nl = 1;
+
+		else if (data[i - 1] == '\\')
+			continue;
+
+		else if (data[i] == '[')
+			level++;
+
+		else if (data[i] == ']') {
+			level--;
+			if (level <= 0)
+				break;
+		}
+	}
+
+	if (i >= size)
+		goto cleanup;
+
+	txt_e = i;
+	i++;
+
+	/* skip any amount of whitespace or newline */
+	/* (this is much more laxist than original markdown syntax) */
+	while (i < size && _isspace(data[i]))
+		i++;
+
+	/* inline style link */
+	if (i < size && data[i] == '(') {
+		/* skipping initial whitespace */
+		i++;
+
+		while (i < size && _isspace(data[i]))
+			i++;
+
+		link_b = i;
+
+		/* looking for link end: ' " ) */
+		while (i < size) {
+			if (data[i] == '\\') i += 2;
+			else if (data[i] == ')') break;
+			else if (i >= 1 && _isspace(data[i-1]) && (data[i] == '\'' || data[i] == '"')) break;
+			else i++;
+		}
+
+		if (i >= size) goto cleanup;
+		link_e = i;
+
+		/* looking for title end if present */
+		if (data[i] == '\'' || data[i] == '"') {
+			qtype = data[i];
+			in_title = 1;
+			i++;
+			title_b = i;
+
+			while (i < size) {
+				if (data[i] == '\\') i += 2;
+				else if (data[i] == qtype) {in_title = 0; i++;}
+				else if ((data[i] == ')') && !in_title) break;
+				else i++;
+			}
+
+			if (i >= size) goto cleanup;
+
+			/* skipping whitespaces after title */
+			title_e = i - 1;
+			while (title_e > title_b && _isspace(data[title_e]))
+				title_e--;
+
+			/* checking for closing quote presence */
+			if (data[title_e] != '\'' &&  data[title_e] != '"') {
+				title_b = title_e = 0;
+				link_e = i;
+			}
+		}
+
+		/* remove whitespace at the end of the link */
+		while (link_e > link_b && _isspace(data[link_e - 1]))
+			link_e--;
+
+		/* remove optional angle brackets around the link */
+		if (data[link_b] == '<') link_b++;
+		if (data[link_e - 1] == '>') link_e--;
+
+		/* building escaped link and title */
+		if (link_e > link_b) {
+			link = rndr_newbuf(rndr, BUFFER_SPAN);
+			bufput(link, data + link_b, link_e - link_b);
+		}
+
+		if (title_e > title_b) {
+			title = rndr_newbuf(rndr, BUFFER_SPAN);
+			bufput(title, data + title_b, title_e - title_b);
+		}
+
+		i++;
+	}
+
+	/* reference style link */
+	else if (i < size && data[i] == '[') {
+		struct buf id = { 0, 0, 0, 0 };
+		struct link_ref *lr;
+
+		/* looking for the id */
+		i++;
+		link_b = i;
+		while (i < size && data[i] != ']') i++;
+		if (i >= size) goto cleanup;
+		link_e = i;
+
+		/* finding the link_ref */
+		if (link_b == link_e) {
+			if (text_has_nl) {
+				struct buf *b = rndr_newbuf(rndr, BUFFER_SPAN);
+				size_t j;
+
+				for (j = 1; j < txt_e; j++) {
+					if (data[j] != '\n')
+						bufputc(b, data[j]);
+					else if (data[j - 1] != ' ')
+						bufputc(b, ' ');
+				}
+
+				id.data = b->data;
+				id.size = b->size;
+			} else {
+				id.data = data + 1;
+				id.size = txt_e - 1;
+			}
+		} else {
+			id.data = data + link_b;
+			id.size = link_e - link_b;
+		}
+
+		lr = find_link_ref(rndr->refs, id.data, id.size);
+		if (!lr)
+			goto cleanup;
+
+		/* keeping link and title from link_ref */
+		link = lr->link;
+		title = lr->title;
+		i++;
+	}
+
+	/* shortcut reference style link */
+	else {
+		struct buf id = { 0, 0, 0, 0 };
+		struct link_ref *lr;
+
+		/* crafting the id */
+		if (text_has_nl) {
+			struct buf *b = rndr_newbuf(rndr, BUFFER_SPAN);
+			size_t j;
+
+			for (j = 1; j < txt_e; j++) {
+				if (data[j] != '\n')
+					bufputc(b, data[j]);
+				else if (data[j - 1] != ' ')
+					bufputc(b, ' ');
+			}
+
+			id.data = b->data;
+			id.size = b->size;
+		} else {
+			id.data = data + 1;
+			id.size = txt_e - 1;
+		}
+
+		/* finding the link_ref */
+		lr = find_link_ref(rndr->refs, id.data, id.size);
+		if (!lr)
+			goto cleanup;
+
+		/* keeping link and title from link_ref */
+		link = lr->link;
+		title = lr->title;
+
+		/* rewinding the whitespace */
+		i = txt_e + 1;
+	}
+
+	/* building content: img alt is escaped, link content is parsed */
+	if (txt_e > 1) {
+		content = rndr_newbuf(rndr, BUFFER_SPAN);
+		if (is_img) {
+			bufput(content, data + 1, txt_e - 1);
+		} else {
+			/* disable autolinking when parsing inline the
+			 * content of a link */
+			rndr->in_link_body = 1;
+			parse_inline(content, rndr, data + 1, txt_e - 1);
+			rndr->in_link_body = 0;
+		}
+	}
+
+	if (link) {
+		u_link = rndr_newbuf(rndr, BUFFER_SPAN);
+		unscape_text(u_link, link);
+	}
+
+	/* calling the relevant rendering function */
+	if (is_img) {
+		if (ob->size && ob->data[ob->size - 1] == '!')
+			ob->size -= 1;
+
+		ret = rndr->cb.image(ob, u_link, title, content, rndr->opaque);
+	} else {
+		ret = rndr->cb.link(ob, u_link, title, content, rndr->opaque);
+	}
+
+	/* cleanup */
+cleanup:
+	rndr->work_bufs[BUFFER_SPAN].size = (int)org_work_size;
+	return ret ? i : 0;
+}
+
+static size_t
+char_superscript(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t offset, size_t size)
+{
+	size_t sup_start, sup_len;
+	struct buf *sup;
+
+	if (!rndr->cb.superscript)
+		return 0;
+
+	if (size < 2)
+		return 0;
+
+	if (data[1] == '(') {
+		sup_start = sup_len = 2;
+
+		while (sup_len < size && data[sup_len] != ')' && data[sup_len - 1] != '\\')
+			sup_len++;
+
+		if (sup_len == size)
+			return 0;
+	} else {
+		sup_start = sup_len = 1;
+
+		while (sup_len < size && !_isspace(data[sup_len]))
+			sup_len++;
+	}
+
+	if (sup_len - sup_start == 0)
+		return (sup_start == 2) ? 3 : 0;
+
+	sup = rndr_newbuf(rndr, BUFFER_SPAN);
+	parse_inline(sup, rndr, data + sup_start, sup_len - sup_start);
+	rndr->cb.superscript(ob, sup, rndr->opaque);
+	rndr_popbuf(rndr, BUFFER_SPAN);
+
+	return (sup_start == 2) ? sup_len + 1 : sup_len;
+}
+
+/*********************************
+ * BLOCK-LEVEL PARSING FUNCTIONS *
+ *********************************/
+
+/* is_empty • returns the line length when it is empty, 0 otherwise */
+static size_t
+is_empty(uint8_t *data, size_t size)
+{
+	size_t i;
+
+	for (i = 0; i < size && data[i] != '\n'; i++)
+		if (data[i] != ' ')
+			return 0;
+
+	return i + 1;
+}
+
+/* is_hrule • returns whether a line is a horizontal rule */
+static int
+is_hrule(uint8_t *data, size_t size)
+{
+	size_t i = 0, n = 0;
+	uint8_t c;
+
+	/* skipping initial spaces */
+	if (size < 3) return 0;
+	if (data[0] == ' ') { i++;
+	if (data[1] == ' ') { i++;
+	if (data[2] == ' ') { i++; } } }
+
+	/* looking at the hrule uint8_t */
+	if (i + 2 >= size
+	|| (data[i] != '*' && data[i] != '-' && data[i] != '_'))
+		return 0;
+	c = data[i];
+
+	/* the whole line must be the char or whitespace */
+	while (i < size && data[i] != '\n') {
+		if (data[i] == c) n++;
+		else if (data[i] != ' ')
+			return 0;
+
+		i++;
+	}
+
+	return n >= 3;
+}
+
+/* check if a line begins with a code fence; return the
+ * width of the code fence */
+static size_t
+prefix_codefence(uint8_t *data, size_t size)
+{
+	size_t i = 0, n = 0;
+	uint8_t c;
+
+	/* skipping initial spaces */
+	if (size < 3) return 0;
+	if (data[0] == ' ') { i++;
+	if (data[1] == ' ') { i++;
+	if (data[2] == ' ') { i++; } } }
+
+	/* looking at the hrule uint8_t */
+	if (i + 2 >= size || !(data[i] == '~' || data[i] == '`'))
+		return 0;
+
+	c = data[i];
+
+	/* the whole line must be the uint8_t or whitespace */
+	while (i < size && data[i] == c) {
+		n++; i++;
+	}
+
+	if (n < 3)
+		return 0;
+
+	return i;
+}
+
+/* check if a line is a code fence; return its size if it is */
+static size_t
+is_codefence(uint8_t *data, size_t size, struct buf *syntax)
+{
+	size_t i = 0, syn_len = 0;
+	uint8_t *syn_start;
+
+	i = prefix_codefence(data, size);
+	if (i == 0)
+		return 0;
+
+	while (i < size && data[i] == ' ')
+		i++;
+
+	syn_start = data + i;
+
+	if (i < size && data[i] == '{') {
+		i++; syn_start++;
+
+		while (i < size && data[i] != '}' && data[i] != '\n') {
+			syn_len++; i++;
+		}
+
+		if (i == size || data[i] != '}')
+			return 0;
+
+		/* strip all whitespace at the beginning and the end
+		 * of the {} block */
+		while (syn_len > 0 && _isspace(syn_start[0])) {
+			syn_start++; syn_len--;
+		}
+
+		while (syn_len > 0 && _isspace(syn_start[syn_len - 1]))
+			syn_len--;
+
+		i++;
+	} else {
+		while (i < size && !_isspace(data[i])) {
+			syn_len++; i++;
+		}
+	}
+
+	if (syntax) {
+		syntax->data = syn_start;
+		syntax->size = syn_len;
+	}
+
+	while (i < size && data[i] != '\n') {
+		if (!_isspace(data[i]))
+			return 0;
+
+		i++;
+	}
+
+	return i + 1;
+}
+
+/* is_atxheader • returns whether the line is a hash-prefixed header */
+static int
+is_atxheader(struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	if (data[0] != '#')
+		return 0;
+
+	if (rndr->ext_flags & MKDEXT_SPACE_HEADERS) {
+		size_t level = 0;
+
+		while (level < size && level < 6 && data[level] == '#')
+			level++;
+
+		if (level < size && data[level] != ' ')
+			return 0;
+	}
+
+	return 1;
+}
+
+/* is_headerline • returns whether the line is a setext-style hdr underline */
+static int
+is_headerline(uint8_t *data, size_t size)
+{
+	size_t i = 0;
+
+	/* test of level 1 header */
+	if (data[i] == '=') {
+		for (i = 1; i < size && data[i] == '='; i++);
+		while (i < size && data[i] == ' ') i++;
+		return (i >= size || data[i] == '\n') ? 1 : 0; }
+
+	/* test of level 2 header */
+	if (data[i] == '-') {
+		for (i = 1; i < size && data[i] == '-'; i++);
+		while (i < size && data[i] == ' ') i++;
+		return (i >= size || data[i] == '\n') ? 2 : 0; }
+
+	return 0;
+}
+
+static int
+is_next_headerline(uint8_t *data, size_t size)
+{
+	size_t i = 0;
+
+	while (i < size && data[i] != '\n')
+		i++;
+
+	if (++i >= size)
+		return 0;
+
+	return is_headerline(data + i, size - i);
+}
+
+/* prefix_quote • returns blockquote prefix length */
+static size_t
+prefix_quote(uint8_t *data, size_t size)
+{
+	size_t i = 0;
+	if (i < size && data[i] == ' ') i++;
+	if (i < size && data[i] == ' ') i++;
+	if (i < size && data[i] == ' ') i++;
+
+	if (i < size && data[i] == '>') {
+		if (i + 1 < size && data[i + 1] == ' ')
+			return i + 2;
+
+		return i + 1;
+	}
+
+	return 0;
+}
+
+/* prefix_code • returns prefix length for block code*/
+static size_t
+prefix_code(uint8_t *data, size_t size)
+{
+	if (size > 3 && data[0] == ' ' && data[1] == ' '
+		&& data[2] == ' ' && data[3] == ' ') return 4;
+
+	return 0;
+}
+
+/* prefix_oli • returns ordered list item prefix */
+static size_t
+prefix_oli(uint8_t *data, size_t size)
+{
+	size_t i = 0;
+
+	if (i < size && data[i] == ' ') i++;
+	if (i < size && data[i] == ' ') i++;
+	if (i < size && data[i] == ' ') i++;
+
+	if (i >= size || data[i] < '0' || data[i] > '9')
+		return 0;
+
+	while (i < size && data[i] >= '0' && data[i] <= '9')
+		i++;
+
+	if (i + 1 >= size || data[i] != '.' || data[i + 1] != ' ')
+		return 0;
+
+	if (is_next_headerline(data + i, size - i))
+		return 0;
+
+	return i + 2;
+}
+
+/* prefix_uli • returns ordered list item prefix */
+static size_t
+prefix_uli(uint8_t *data, size_t size)
+{
+	size_t i = 0;
+
+	if (i < size && data[i] == ' ') i++;
+	if (i < size && data[i] == ' ') i++;
+	if (i < size && data[i] == ' ') i++;
+
+	if (i + 1 >= size ||
+		(data[i] != '*' && data[i] != '+' && data[i] != '-') ||
+		data[i + 1] != ' ')
+		return 0;
+
+	if (is_next_headerline(data + i, size - i))
+		return 0;
+
+	return i + 2;
+}
+
+
+/* parse_block • parsing of one block, returning next uint8_t to parse */
+static void parse_block(struct buf *ob, struct sd_markdown *rndr,
+			uint8_t *data, size_t size);
+
+
+/* parse_blockquote • handles parsing of a blockquote fragment */
+static size_t
+parse_blockquote(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t beg, end = 0, pre, work_size = 0;
+	uint8_t *work_data = 0;
+	struct buf *out = 0;
+
+	out = rndr_newbuf(rndr, BUFFER_BLOCK);
+	beg = 0;
+	while (beg < size) {
+		for (end = beg + 1; end < size && data[end - 1] != '\n'; end++);
+
+		pre = prefix_quote(data + beg, end - beg);
+
+		if (pre)
+			beg += pre; /* skipping prefix */
+
+		/* empty line followed by non-quote line */
+		else if (is_empty(data + beg, end - beg) &&
+				(end >= size || (prefix_quote(data + end, size - end) == 0 &&
+				!is_empty(data + end, size - end))))
+			break;
+
+		if (beg < end) { /* copy into the in-place working buffer */
+			/* bufput(work, data + beg, end - beg); */
+			if (!work_data)
+				work_data = data + beg;
+			else if (data + beg != work_data + work_size)
+				memmove(work_data + work_size, data + beg, end - beg);
+			work_size += end - beg;
+		}
+		beg = end;
+	}
+
+	parse_block(out, rndr, work_data, work_size);
+	if (rndr->cb.blockquote)
+		rndr->cb.blockquote(ob, out, rndr->opaque);
+	rndr_popbuf(rndr, BUFFER_BLOCK);
+	return end;
+}
+
+static size_t
+parse_htmlblock(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int do_render);
+
+/* parse_blockquote • handles parsing of a regular paragraph */
+static size_t
+parse_paragraph(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t i = 0, end = 0;
+	int level = 0;
+	struct buf work = { data, 0, 0, 0 };
+
+	while (i < size) {
+		for (end = i + 1; end < size && data[end - 1] != '\n'; end++) /* empty */;
+
+		if (is_empty(data + i, size - i))
+			break;
+
+		if ((level = is_headerline(data + i, size - i)) != 0)
+			break;
+
+		if (is_atxheader(rndr, data + i, size - i) ||
+			is_hrule(data + i, size - i) ||
+			prefix_quote(data + i, size - i)) {
+			end = i;
+			break;
+		}
+
+		/*
+		 * Early termination of a paragraph with the same logic
+		 * as Markdown 1.0.0. If this logic is applied, the
+		 * Markdown 1.0.3 test suite won't pass cleanly
+		 *
+		 * :: If the first character in a new line is not a letter,
+		 * let's check to see if there's some kind of block starting
+		 * here
+		 */
+		if ((rndr->ext_flags & MKDEXT_LAX_SPACING) && !isalnum(data[i])) {
+			if (prefix_oli(data + i, size - i) ||
+				prefix_uli(data + i, size - i)) {
+				end = i;
+				break;
+			}
+
+			/* see if an html block starts here */
+			if (data[i] == '<' && rndr->cb.blockhtml &&
+				parse_htmlblock(ob, rndr, data + i, size - i, 0)) {
+				end = i;
+				break;
+			}
+
+			/* see if a code fence starts here */
+			if ((rndr->ext_flags & MKDEXT_FENCED_CODE) != 0 &&
+				is_codefence(data + i, size - i, NULL) != 0) {
+				end = i;
+				break;
+			}
+		}
+
+		i = end;
+	}
+
+	work.size = i;
+	while (work.size && data[work.size - 1] == '\n')
+		work.size--;
+
+	if (!level) {
+		struct buf *tmp = rndr_newbuf(rndr, BUFFER_BLOCK);
+		parse_inline(tmp, rndr, work.data, work.size);
+		if (rndr->cb.paragraph)
+			rndr->cb.paragraph(ob, tmp, rndr->opaque);
+		rndr_popbuf(rndr, BUFFER_BLOCK);
+	} else {
+		struct buf *header_work;
+
+		if (work.size) {
+			size_t beg;
+			i = work.size;
+			work.size -= 1;
+
+			while (work.size && data[work.size] != '\n')
+				work.size -= 1;
+
+			beg = work.size + 1;
+			while (work.size && data[work.size - 1] == '\n')
+				work.size -= 1;
+
+			if (work.size > 0) {
+				struct buf *tmp = rndr_newbuf(rndr, BUFFER_BLOCK);
+				parse_inline(tmp, rndr, work.data, work.size);
+
+				if (rndr->cb.paragraph)
+					rndr->cb.paragraph(ob, tmp, rndr->opaque);
+
+				rndr_popbuf(rndr, BUFFER_BLOCK);
+				work.data += beg;
+				work.size = i - beg;
+			}
+			else work.size = i;
+		}
+
+		header_work = rndr_newbuf(rndr, BUFFER_SPAN);
+		parse_inline(header_work, rndr, work.data, work.size);
+
+		if (rndr->cb.header)
+			rndr->cb.header(ob, header_work, (int)level, rndr->opaque);
+
+		rndr_popbuf(rndr, BUFFER_SPAN);
+	}
+
+	return end;
+}
+
+/* parse_fencedcode • handles parsing of a block-level code fragment */
+static size_t
+parse_fencedcode(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t beg, end;
+	struct buf *work = 0;
+	struct buf lang = { 0, 0, 0, 0 };
+
+	beg = is_codefence(data, size, &lang);
+	if (beg == 0) return 0;
+
+	work = rndr_newbuf(rndr, BUFFER_BLOCK);
+
+	while (beg < size) {
+		size_t fence_end;
+		struct buf fence_trail = { 0, 0, 0, 0 };
+
+		fence_end = is_codefence(data + beg, size - beg, &fence_trail);
+		if (fence_end != 0 && fence_trail.size == 0) {
+			beg += fence_end;
+			break;
+		}
+
+		for (end = beg + 1; end < size && data[end - 1] != '\n'; end++);
+
+		if (beg < end) {
+			/* verbatim copy to the working buffer,
+				escaping entities */
+			if (is_empty(data + beg, end - beg))
+				bufputc(work, '\n');
+			else bufput(work, data + beg, end - beg);
+		}
+		beg = end;
+	}
+
+	if (work->size && work->data[work->size - 1] != '\n')
+		bufputc(work, '\n');
+
+	if (rndr->cb.blockcode)
+		rndr->cb.blockcode(ob, work, lang.size ? &lang : NULL, rndr->opaque);
+
+	rndr_popbuf(rndr, BUFFER_BLOCK);
+	return beg;
+}
+
+static size_t
+parse_blockcode(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t beg, end, pre;
+	struct buf *work = 0;
+
+	work = rndr_newbuf(rndr, BUFFER_BLOCK);
+
+	beg = 0;
+	while (beg < size) {
+		for (end = beg + 1; end < size && data[end - 1] != '\n'; end++) {};
+		pre = prefix_code(data + beg, end - beg);
+
+		if (pre)
+			beg += pre; /* skipping prefix */
+		else if (!is_empty(data + beg, end - beg))
+			/* non-empty non-prefixed line breaks the pre */
+			break;
+
+		if (beg < end) {
+			/* verbatim copy to the working buffer,
+				escaping entities */
+			if (is_empty(data + beg, end - beg))
+				bufputc(work, '\n');
+			else bufput(work, data + beg, end - beg);
+		}
+		beg = end;
+	}
+
+	while (work->size && work->data[work->size - 1] == '\n')
+		work->size -= 1;
+
+	bufputc(work, '\n');
+
+	if (rndr->cb.blockcode)
+		rndr->cb.blockcode(ob, work, NULL, rndr->opaque);
+
+	rndr_popbuf(rndr, BUFFER_BLOCK);
+	return beg;
+}
+
+/* parse_listitem • parsing of a single list item */
+/*	assuming initial prefix is already removed */
+static size_t
+parse_listitem(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int *flags)
+{
+	struct buf *work = 0, *inter = 0;
+	size_t beg = 0, end, pre, sublist = 0, orgpre = 0, i;
+	int in_empty = 0, has_inside_empty = 0, in_fence = 0;
+
+	/* keeping track of the first indentation prefix */
+	while (orgpre < 3 && orgpre < size && data[orgpre] == ' ')
+		orgpre++;
+
+	beg = prefix_uli(data, size);
+	if (!beg)
+		beg = prefix_oli(data, size);
+
+	if (!beg)
+		return 0;
+
+	/* skipping to the beginning of the following line */
+	end = beg;
+	while (end < size && data[end - 1] != '\n')
+		end++;
+
+	/* getting working buffers */
+	work = rndr_newbuf(rndr, BUFFER_SPAN);
+	inter = rndr_newbuf(rndr, BUFFER_SPAN);
+
+	/* putting the first line into the working buffer */
+	bufput(work, data + beg, end - beg);
+	beg = end;
+
+	/* process the following lines */
+	while (beg < size) {
+		size_t has_next_uli = 0, has_next_oli = 0;
+
+		end++;
+
+		while (end < size && data[end - 1] != '\n')
+			end++;
+
+		/* process an empty line */
+		if (is_empty(data + beg, end - beg)) {
+			in_empty = 1;
+			beg = end;
+			continue;
+		}
+
+		/* calculating the indentation */
+		i = 0;
+		while (i < 4 && beg + i < end && data[beg + i] == ' ')
+			i++;
+
+		pre = i;
+
+		if (rndr->ext_flags & MKDEXT_FENCED_CODE) {
+			if (is_codefence(data + beg + i, end - beg - i, NULL) != 0)
+				in_fence = !in_fence;
+		}
+
+		/* Only check for new list items if we are **not** inside
+		 * a fenced code block */
+		if (!in_fence) {
+			has_next_uli = prefix_uli(data + beg + i, end - beg - i);
+			has_next_oli = prefix_oli(data + beg + i, end - beg - i);
+		}
+
+		/* checking for ul/ol switch */
+		if (in_empty && (
+			((*flags & MKD_LIST_ORDERED) && has_next_uli) ||
+			(!(*flags & MKD_LIST_ORDERED) && has_next_oli))){
+			*flags |= MKD_LI_END;
+			break; /* the following item must have same list type */
+		}
+
+		/* checking for a new item */
+		if ((has_next_uli && !is_hrule(data + beg + i, end - beg - i)) || has_next_oli) {
+			if (in_empty)
+				has_inside_empty = 1;
+
+			if (pre == orgpre) /* the following item must have */
+				break;             /* the same indentation */
+
+			if (!sublist)
+				sublist = work->size;
+		}
+		/* joining only indented stuff after empty lines;
+		 * note that now we only require 1 space of indentation
+		 * to continue a list */
+		else if (in_empty && pre == 0) {
+			*flags |= MKD_LI_END;
+			break;
+		}
+		else if (in_empty) {
+			bufputc(work, '\n');
+			has_inside_empty = 1;
+		}
+
+		in_empty = 0;
+
+		/* adding the line without prefix into the working buffer */
+		bufput(work, data + beg + i, end - beg - i);
+		beg = end;
+	}
+
+	/* render of li contents */
+	if (has_inside_empty)
+		*flags |= MKD_LI_BLOCK;
+
+	if (*flags & MKD_LI_BLOCK) {
+		/* intermediate render of block li */
+		if (sublist && sublist < work->size) {
+			parse_block(inter, rndr, work->data, sublist);
+			parse_block(inter, rndr, work->data + sublist, work->size - sublist);
+		}
+		else
+			parse_block(inter, rndr, work->data, work->size);
+	} else {
+		/* intermediate render of inline li */
+		if (sublist && sublist < work->size) {
+			parse_inline(inter, rndr, work->data, sublist);
+			parse_block(inter, rndr, work->data + sublist, work->size - sublist);
+		}
+		else
+			parse_inline(inter, rndr, work->data, work->size);
+	}
+
+	/* render of li itself */
+	if (rndr->cb.listitem)
+		rndr->cb.listitem(ob, inter, *flags, rndr->opaque);
+
+	rndr_popbuf(rndr, BUFFER_SPAN);
+	rndr_popbuf(rndr, BUFFER_SPAN);
+	return beg;
+}
+
+
+/* parse_list • parsing ordered or unordered list block */
+static size_t
+parse_list(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int flags)
+{
+	struct buf *work = 0;
+	size_t i = 0, j;
+
+	work = rndr_newbuf(rndr, BUFFER_BLOCK);
+
+	while (i < size) {
+		j = parse_listitem(work, rndr, data + i, size - i, &flags);
+		i += j;
+
+		if (!j || (flags & MKD_LI_END))
+			break;
+	}
+
+	if (rndr->cb.list)
+		rndr->cb.list(ob, work, flags, rndr->opaque);
+	rndr_popbuf(rndr, BUFFER_BLOCK);
+	return i;
+}
+
+/* parse_atxheader • parsing of atx-style headers */
+static size_t
+parse_atxheader(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t level = 0;
+	size_t i, end, skip;
+
+	while (level < size && level < 6 && data[level] == '#')
+		level++;
+
+	for (i = level; i < size && data[i] == ' '; i++);
+
+	for (end = i; end < size && data[end] != '\n'; end++);
+	skip = end;
+
+	while (end && data[end - 1] == '#')
+		end--;
+
+	while (end && data[end - 1] == ' ')
+		end--;
+
+	if (end > i) {
+		struct buf *work = rndr_newbuf(rndr, BUFFER_SPAN);
+
+		parse_inline(work, rndr, data + i, end - i);
+
+		if (rndr->cb.header)
+			rndr->cb.header(ob, work, (int)level, rndr->opaque);
+
+		rndr_popbuf(rndr, BUFFER_SPAN);
+	}
+
+	return skip;
+}
+
+
+/* htmlblock_end • checking end of HTML block : </tag>[ \t]*\n[ \t*]\n */
+/*	returns the length on match, 0 otherwise */
+static size_t
+htmlblock_end_tag(
+	const char *tag,
+	size_t tag_len,
+	struct sd_markdown *rndr,
+	uint8_t *data,
+	size_t size)
+{
+	size_t i, w;
+
+	/* checking if tag is a match */
+	if (tag_len + 3 >= size ||
+		strncasecmp((char *)data + 2, tag, tag_len) != 0 ||
+		data[tag_len + 2] != '>')
+		return 0;
+
+	/* checking white lines */
+	i = tag_len + 3;
+	w = 0;
+	if (i < size && (w = is_empty(data + i, size - i)) == 0)
+		return 0; /* non-blank after tag */
+	i += w;
+	w = 0;
+
+	if (i < size)
+		w = is_empty(data + i, size - i);
+
+	return i + w;
+}
+
+static size_t
+htmlblock_end(const char *curtag,
+	struct sd_markdown *rndr,
+	uint8_t *data,
+	size_t size,
+	int start_of_line)
+{
+	size_t tag_size = strlen(curtag);
+	size_t i = 1, end_tag;
+	int block_lines = 0;
+
+	while (i < size) {
+		i++;
+		while (i < size && !(data[i - 1] == '<' && data[i] == '/')) {
+			if (data[i] == '\n')
+				block_lines++;
+
+			i++;
+		}
+
+		/* If we are only looking for unindented tags, skip the tag
+		 * if it doesn't follow a newline.
+		 *
+		 * The only exception to this is if the tag is still on the
+		 * initial line; in that case it still counts as a closing
+		 * tag
+		 */
+		if (start_of_line && block_lines > 0 && data[i - 2] != '\n')
+			continue;
+
+		if (i + 2 + tag_size >= size)
+			break;
+
+		end_tag = htmlblock_end_tag(curtag, tag_size, rndr, data + i - 1, size - i + 1);
+		if (end_tag)
+			return i + end_tag - 1;
+	}
+
+	return 0;
+}
+
+
+/* parse_htmlblock • parsing of inline HTML block */
+static size_t
+parse_htmlblock(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size, int do_render)
+{
+	size_t i, j = 0, tag_end;
+	const char *curtag = NULL;
+	struct buf work = { data, 0, 0, 0 };
+
+	/* identification of the opening tag */
+	if (size < 2 || data[0] != '<')
+		return 0;
+
+	i = 1;
+	while (i < size && data[i] != '>' && data[i] != ' ')
+		i++;
+
+	if (i < size)
+		curtag = find_block_tag((char *)data + 1, (int)i - 1);
+
+	/* handling of special cases */
+	if (!curtag) {
+
+		/* HTML comment, laxist form */
+		if (size > 5 && data[1] == '!' && data[2] == '-' && data[3] == '-') {
+			i = 5;
+
+			while (i < size && !(data[i - 2] == '-' && data[i - 1] == '-' && data[i] == '>'))
+				i++;
+
+			i++;
+
+			if (i < size)
+				j = is_empty(data + i, size - i);
+
+			if (j) {
+				work.size = i + j;
+				if (do_render && rndr->cb.blockhtml)
+					rndr->cb.blockhtml(ob, &work, rndr->opaque);
+				return work.size;
+			}
+		}
+
+		/* HR, which is the only self-closing block tag considered */
+		if (size > 4 && (data[1] == 'h' || data[1] == 'H') && (data[2] == 'r' || data[2] == 'R')) {
+			i = 3;
+			while (i < size && data[i] != '>')
+				i++;
+
+			if (i + 1 < size) {
+				i++;
+				j = is_empty(data + i, size - i);
+				if (j) {
+					work.size = i + j;
+					if (do_render && rndr->cb.blockhtml)
+						rndr->cb.blockhtml(ob, &work, rndr->opaque);
+					return work.size;
+				}
+			}
+		}
+
+		/* no special case recognised */
+		return 0;
+	}
+
+	/* looking for an unindented matching closing tag */
+	/*	followed by a blank line */
+	tag_end = htmlblock_end(curtag, rndr, data, size, 1);
+
+	/* if not found, trying a second pass looking for indented match */
+	/* but not if tag is "ins" or "del" (following original Markdown.pl) */
+	if (!tag_end && strcmp(curtag, "ins") != 0 && strcmp(curtag, "del") != 0) {
+		tag_end = htmlblock_end(curtag, rndr, data, size, 0);
+	}
+
+	if (!tag_end)
+		return 0;
+
+	/* the end of the block has been found */
+	work.size = tag_end;
+	if (do_render && rndr->cb.blockhtml)
+		rndr->cb.blockhtml(ob, &work, rndr->opaque);
+
+	return tag_end;
+}
+
+static void
+parse_table_row(
+	struct buf *ob,
+	struct sd_markdown *rndr,
+	uint8_t *data,
+	size_t size,
+	size_t columns,
+	int *col_data,
+	int header_flag)
+{
+	size_t i = 0, col;
+	struct buf *row_work = 0;
+
+	if (!rndr->cb.table_cell || !rndr->cb.table_row)
+		return;
+
+	row_work = rndr_newbuf(rndr, BUFFER_SPAN);
+
+	if (i < size && data[i] == '|')
+		i++;
+
+	for (col = 0; col < columns && i < size; ++col) {
+		size_t cell_start, cell_end;
+		struct buf *cell_work;
+
+		cell_work = rndr_newbuf(rndr, BUFFER_SPAN);
+
+		while (i < size && _isspace(data[i]))
+			i++;
+
+		cell_start = i;
+
+		while (i < size && data[i] != '|')
+			i++;
+
+		cell_end = i - 1;
+
+		while (cell_end > cell_start && _isspace(data[cell_end]))
+			cell_end--;
+
+		parse_inline(cell_work, rndr, data + cell_start, 1 + cell_end - cell_start);
+		rndr->cb.table_cell(row_work, cell_work, col_data[col] | header_flag, rndr->opaque);
+
+		rndr_popbuf(rndr, BUFFER_SPAN);
+		i++;
+	}
+
+	for (; col < columns; ++col) {
+		struct buf empty_cell = { 0, 0, 0, 0 };
+		rndr->cb.table_cell(row_work, &empty_cell, col_data[col] | header_flag, rndr->opaque);
+	}
+
+	rndr->cb.table_row(ob, row_work, rndr->opaque);
+
+	rndr_popbuf(rndr, BUFFER_SPAN);
+}
+
+static size_t
+parse_table_header(
+	struct buf *ob,
+	struct sd_markdown *rndr,
+	uint8_t *data,
+	size_t size,
+	size_t *columns,
+	int **column_data)
+{
+	int pipes;
+	size_t i = 0, col, header_end, under_end;
+
+	pipes = 0;
+	while (i < size && data[i] != '\n')
+		if (data[i++] == '|')
+			pipes++;
+
+	if (i == size || pipes == 0)
+		return 0;
+
+	header_end = i;
+
+	while (header_end > 0 && _isspace(data[header_end - 1]))
+		header_end--;
+
+	if (data[0] == '|')
+		pipes--;
+
+	if (header_end && data[header_end - 1] == '|')
+		pipes--;
+
+	*columns = pipes + 1;
+	*column_data = calloc(*columns, sizeof(int));
+
+	/* Parse the header underline */
+	i++;
+	if (i < size && data[i] == '|')
+		i++;
+
+	under_end = i;
+	while (under_end < size && data[under_end] != '\n')
+		under_end++;
+
+	for (col = 0; col < *columns && i < under_end; ++col) {
+		size_t dashes = 0;
+
+		while (i < under_end && data[i] == ' ')
+			i++;
+
+		if (data[i] == ':') {
+			i++; (*column_data)[col] |= MKD_TABLE_ALIGN_L;
+			dashes++;
+		}
+
+		while (i < under_end && data[i] == '-') {
+			i++; dashes++;
+		}
+
+		if (i < under_end && data[i] == ':') {
+			i++; (*column_data)[col] |= MKD_TABLE_ALIGN_R;
+			dashes++;
+		}
+
+		while (i < under_end && data[i] == ' ')
+			i++;
+
+		if (i < under_end && data[i] != '|')
+			break;
+
+		if (dashes < 3)
+			break;
+
+		i++;
+	}
+
+	if (col < *columns)
+		return 0;
+
+	parse_table_row(
+		ob, rndr, data,
+		header_end,
+		*columns,
+		*column_data,
+		MKD_TABLE_HEADER
+	);
+
+	return under_end + 1;
+}
+
+static size_t
+parse_table(
+	struct buf *ob,
+	struct sd_markdown *rndr,
+	uint8_t *data,
+	size_t size)
+{
+	size_t i;
+
+	struct buf *header_work = 0;
+	struct buf *body_work = 0;
+
+	size_t columns;
+	int *col_data = NULL;
+
+	header_work = rndr_newbuf(rndr, BUFFER_SPAN);
+	body_work = rndr_newbuf(rndr, BUFFER_BLOCK);
+
+	i = parse_table_header(header_work, rndr, data, size, &columns, &col_data);
+	if (i > 0) {
+
+		while (i < size) {
+			size_t row_start;
+			int pipes = 0;
+
+			row_start = i;
+
+			while (i < size && data[i] != '\n')
+				if (data[i++] == '|')
+					pipes++;
+
+			if (pipes == 0 || i == size) {
+				i = row_start;
+				break;
+			}
+
+			parse_table_row(
+				body_work,
+				rndr,
+				data + row_start,
+				i - row_start,
+				columns,
+				col_data, 0
+			);
+
+			i++;
+		}
+
+		if (rndr->cb.table)
+			rndr->cb.table(ob, header_work, body_work, rndr->opaque);
+	}
+
+	free(col_data);
+	rndr_popbuf(rndr, BUFFER_SPAN);
+	rndr_popbuf(rndr, BUFFER_BLOCK);
+	return i;
+}
+
+/* parse_block • parsing of one block, returning next uint8_t to parse */
+static void
+parse_block(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	size_t beg, end, i;
+	uint8_t *txt_data;
+	beg = 0;
+
+	if (rndr->work_bufs[BUFFER_SPAN].size +
+		rndr->work_bufs[BUFFER_BLOCK].size > rndr->max_nesting)
+		return;
+
+	while (beg < size) {
+		txt_data = data + beg;
+		end = size - beg;
+
+		if (is_atxheader(rndr, txt_data, end))
+			beg += parse_atxheader(ob, rndr, txt_data, end);
+
+		else if (data[beg] == '<' && rndr->cb.blockhtml &&
+				(i = parse_htmlblock(ob, rndr, txt_data, end, 1)) != 0)
+			beg += i;
+
+		else if ((i = is_empty(txt_data, end)) != 0)
+			beg += i;
+
+		else if (is_hrule(txt_data, end)) {
+			if (rndr->cb.hrule)
+				rndr->cb.hrule(ob, rndr->opaque);
+
+			while (beg < size && data[beg] != '\n')
+				beg++;
+
+			beg++;
+		}
+
+		else if ((rndr->ext_flags & MKDEXT_FENCED_CODE) != 0 &&
+			(i = parse_fencedcode(ob, rndr, txt_data, end)) != 0)
+			beg += i;
+
+		else if ((rndr->ext_flags & MKDEXT_TABLES) != 0 &&
+			(i = parse_table(ob, rndr, txt_data, end)) != 0)
+			beg += i;
+
+		else if (prefix_quote(txt_data, end))
+			beg += parse_blockquote(ob, rndr, txt_data, end);
+
+		else if (prefix_code(txt_data, end))
+			beg += parse_blockcode(ob, rndr, txt_data, end);
+
+		else if (prefix_uli(txt_data, end))
+			beg += parse_list(ob, rndr, txt_data, end, 0);
+
+		else if (prefix_oli(txt_data, end))
+			beg += parse_list(ob, rndr, txt_data, end, MKD_LIST_ORDERED);
+
+		else
+			beg += parse_paragraph(ob, rndr, txt_data, end);
+	}
+}
+
+
+
+/*********************
+ * REFERENCE PARSING *
+ *********************/
+
+/* is_ref • returns whether a line is a reference or not */
+static int
+is_ref(const uint8_t *data, size_t beg, size_t end, size_t *last, struct link_ref **refs)
+{
+/*	int n; */
+	size_t i = 0;
+	size_t id_offset, id_end;
+	size_t link_offset, link_end;
+	size_t title_offset, title_end;
+	size_t line_end;
+
+	/* up to 3 optional leading spaces */
+	if (beg + 3 >= end) return 0;
+	if (data[beg] == ' ') { i = 1;
+	if (data[beg + 1] == ' ') { i = 2;
+	if (data[beg + 2] == ' ') { i = 3;
+	if (data[beg + 3] == ' ') return 0; } } }
+	i += beg;
+
+	/* id part: anything but a newline between brackets */
+	if (data[i] != '[') return 0;
+	i++;
+	id_offset = i;
+	while (i < end && data[i] != '\n' && data[i] != '\r' && data[i] != ']')
+		i++;
+	if (i >= end || data[i] != ']') return 0;
+	id_end = i;
+
+	/* spacer: colon (space | tab)* newline? (space | tab)* */
+	i++;
+	if (i >= end || data[i] != ':') return 0;
+	i++;
+	while (i < end && data[i] == ' ') i++;
+	if (i < end && (data[i] == '\n' || data[i] == '\r')) {
+		i++;
+		if (i < end && data[i] == '\r' && data[i - 1] == '\n') i++; }
+	while (i < end && data[i] == ' ') i++;
+	if (i >= end) return 0;
+
+	/* link: whitespace-free sequence, optionally between angle brackets */
+	if (data[i] == '<')
+		i++;
+
+	link_offset = i;
+
+	while (i < end && data[i] != ' ' && data[i] != '\n' && data[i] != '\r')
+		i++;
+
+	if (data[i - 1] == '>') link_end = i - 1;
+	else link_end = i;
+
+	/* optional spacer: (space | tab)* (newline | '\'' | '"' | '(' ) */
+	while (i < end && data[i] == ' ') i++;
+	if (i < end && data[i] != '\n' && data[i] != '\r'
+			&& data[i] != '\'' && data[i] != '"' && data[i] != '(')
+		return 0;
+	line_end = 0;
+	/* computing end-of-line */
+	if (i >= end || data[i] == '\r' || data[i] == '\n') line_end = i;
+	if (i + 1 < end && data[i] == '\n' && data[i + 1] == '\r')
+		line_end = i + 1;
+
+	/* optional (space|tab)* spacer after a newline */
+	if (line_end) {
+		i = line_end + 1;
+		while (i < end && data[i] == ' ') i++; }
+
+	/* optional title: any non-newline sequence enclosed in '"()
+					alone on its line */
+	title_offset = title_end = 0;
+	if (i + 1 < end
+	&& (data[i] == '\'' || data[i] == '"' || data[i] == '(')) {
+		i++;
+		title_offset = i;
+		/* looking for EOL */
+		while (i < end && data[i] != '\n' && data[i] != '\r') i++;
+		if (i + 1 < end && data[i] == '\n' && data[i + 1] == '\r')
+			title_end = i + 1;
+		else	title_end = i;
+		/* stepping back */
+		i -= 1;
+		while (i > title_offset && data[i] == ' ')
+			i -= 1;
+		if (i > title_offset
+		&& (data[i] == '\'' || data[i] == '"' || data[i] == ')')) {
+			line_end = title_end;
+			title_end = i; } }
+
+	if (!line_end || link_end == link_offset)
+		return 0; /* garbage after the link empty link */
+
+	/* a valid ref has been found, filling-in return structures */
+	if (last)
+		*last = line_end;
+
+	if (refs) {
+		struct link_ref *ref;
+
+		ref = add_link_ref(refs, data + id_offset, id_end - id_offset);
+		if (!ref)
+			return 0;
+
+		ref->link = bufnew(link_end - link_offset);
+		bufput(ref->link, data + link_offset, link_end - link_offset);
+
+		if (title_end > title_offset) {
+			ref->title = bufnew(title_end - title_offset);
+			bufput(ref->title, data + title_offset, title_end - title_offset);
+		}
+	}
+
+	return 1;
+}
+
+static void expand_tabs(struct buf *ob, const uint8_t *line, size_t size)
+{
+	size_t  i = 0, tab = 0;
+
+	while (i < size) {
+		size_t org = i;
+
+		while (i < size && line[i] != '\t') {
+			i++; tab++;
+		}
+
+		if (i > org)
+			bufput(ob, line + org, i - org);
+
+		if (i >= size)
+			break;
+
+		do {
+			bufputc(ob, ' '); tab++;
+		} while (tab % 4);
+
+		i++;
+	}
+}
+
+/**********************
+ * EXPORTED FUNCTIONS *
+ **********************/
+
+struct sd_markdown *
+sd_markdown_new(
+	unsigned int extensions,
+	size_t max_nesting,
+	const struct sd_callbacks *callbacks,
+	void *opaque)
+{
+	struct sd_markdown *md = NULL;
+
+	assert(max_nesting > 0 && callbacks);
+
+	md = malloc(sizeof(struct sd_markdown));
+	if (!md)
+		return NULL;
+
+	memcpy(&md->cb, callbacks, sizeof(struct sd_callbacks));
+
+	stack_init(&md->work_bufs[BUFFER_BLOCK], 4);
+	stack_init(&md->work_bufs[BUFFER_SPAN], 8);
+
+	memset(md->active_char, 0x0, 256);
+
+	if (md->cb.emphasis || md->cb.double_emphasis || md->cb.triple_emphasis) {
+		md->active_char['*'] = MD_CHAR_EMPHASIS;
+		md->active_char['_'] = MD_CHAR_EMPHASIS;
+		if (extensions & MKDEXT_STRIKETHROUGH)
+			md->active_char['~'] = MD_CHAR_EMPHASIS;
+	}
+
+	if (md->cb.codespan)
+		md->active_char['`'] = MD_CHAR_CODESPAN;
+
+	if (md->cb.linebreak)
+		md->active_char['\n'] = MD_CHAR_LINEBREAK;
+
+	if (md->cb.image || md->cb.link)
+		md->active_char['['] = MD_CHAR_LINK;
+
+	md->active_char['<'] = MD_CHAR_LANGLE;
+	md->active_char['\\'] = MD_CHAR_ESCAPE;
+	md->active_char['&'] = MD_CHAR_ENTITITY;
+
+	if (extensions & MKDEXT_AUTOLINK) {
+		md->active_char[':'] = MD_CHAR_AUTOLINK_URL;
+		md->active_char['@'] = MD_CHAR_AUTOLINK_EMAIL;
+		md->active_char['w'] = MD_CHAR_AUTOLINK_WWW;
+	}
+
+	if (extensions & MKDEXT_SUPERSCRIPT)
+		md->active_char['^'] = MD_CHAR_SUPERSCRIPT;
+
+	/* Extension data */
+	md->ext_flags = extensions;
+	md->opaque = opaque;
+	md->max_nesting = max_nesting;
+	md->in_link_body = 0;
+
+	return md;
+}
+
+void
+sd_markdown_render(struct buf *ob, const uint8_t *document, size_t doc_size, struct sd_markdown *md)
+{
+#define MARKDOWN_GROW(x) ((x) + ((x) >> 1))
+	static const char UTF8_BOM[] = {0xEF, 0xBB, 0xBF};
+
+	struct buf *text;
+	size_t beg, end;
+
+	text = bufnew(64);
+	if (!text)
+		return;
+
+	/* Preallocate enough space for our buffer to avoid expanding while copying */
+	bufgrow(text, doc_size);
+
+	/* reset the references table */
+	memset(&md->refs, 0x0, REF_TABLE_SIZE * sizeof(void *));
+
+	/* first pass: looking for references, copying everything else */
+	beg = 0;
+
+	/* Skip a possible UTF-8 BOM, even though the Unicode standard
+	 * discourages having these in UTF-8 documents */
+	if (doc_size >= 3 && memcmp(document, UTF8_BOM, 3) == 0)
+		beg += 3;
+
+	while (beg < doc_size) /* iterating over lines */
+		if (is_ref(document, beg, doc_size, &end, md->refs))
+			beg = end;
+		else { /* skipping to the next line */
+			end = beg;
+			while (end < doc_size && document[end] != '\n' && document[end] != '\r')
+				end++;
+
+			/* adding the line body if present */
+			if (end > beg)
+				expand_tabs(text, document + beg, end - beg);
+
+			while (end < doc_size && (document[end] == '\n' || document[end] == '\r')) {
+				/* add one \n per newline */
+				if (document[end] == '\n' || (end + 1 < doc_size && document[end + 1] != '\n'))
+					bufputc(text, '\n');
+				end++;
+			}
+
+			beg = end;
+		}
+
+	/* pre-grow the output buffer to minimize allocations */
+	bufgrow(ob, MARKDOWN_GROW(text->size));
+
+	/* second pass: actual rendering */
+	if (md->cb.doc_header)
+		md->cb.doc_header(ob, md->opaque);
+
+	if (text->size) {
+		/* adding a final newline if not already present */
+		if (text->data[text->size - 1] != '\n' &&  text->data[text->size - 1] != '\r')
+			bufputc(text, '\n');
+
+		parse_block(ob, md, text->data, text->size);
+	}
+
+	if (md->cb.doc_footer)
+		md->cb.doc_footer(ob, md->opaque);
+
+	/* clean-up */
+	bufrelease(text);
+	free_link_refs(md->refs);
+
+	assert(md->work_bufs[BUFFER_SPAN].size == 0);
+	assert(md->work_bufs[BUFFER_BLOCK].size == 0);
+}
+
+void
+sd_markdown_free(struct sd_markdown *md)
+{
+	size_t i;
+
+	for (i = 0; i < (size_t)md->work_bufs[BUFFER_SPAN].asize; ++i)
+		bufrelease(md->work_bufs[BUFFER_SPAN].item[i]);
+
+	for (i = 0; i < (size_t)md->work_bufs[BUFFER_BLOCK].asize; ++i)
+		bufrelease(md->work_bufs[BUFFER_BLOCK].item[i]);
+
+	stack_free(&md->work_bufs[BUFFER_SPAN]);
+	stack_free(&md->work_bufs[BUFFER_BLOCK]);
+
+	free(md);
+}
+
+void
+sd_version(int *ver_major, int *ver_minor, int *ver_revision)
+{
+	*ver_major = SUNDOWN_VER_MAJOR;
+	*ver_minor = SUNDOWN_VER_MINOR;
+	*ver_revision = SUNDOWN_VER_REVISION;
+}
+
+/* vim: set filetype=c: */
diff --git a/src/rt/sundown/src/markdown.h b/src/rt/sundown/src/markdown.h
new file mode 100644
index 0000000000000..6f6553ec87df5
--- /dev/null
+++ b/src/rt/sundown/src/markdown.h
@@ -0,0 +1,138 @@
+/* markdown.h - generic markdown parser */
+
+/*
+ * Copyright (c) 2009, Natacha Porté
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef UPSKIRT_MARKDOWN_H
+#define UPSKIRT_MARKDOWN_H
+
+#include "buffer.h"
+#include "autolink.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define SUNDOWN_VERSION "1.16.0"
+#define SUNDOWN_VER_MAJOR 1
+#define SUNDOWN_VER_MINOR 16
+#define SUNDOWN_VER_REVISION 0
+
+/********************
+ * TYPE DEFINITIONS *
+ ********************/
+
+/* mkd_autolink - type of autolink */
+enum mkd_autolink {
+	MKDA_NOT_AUTOLINK,	/* used internally when it is not an autolink*/
+	MKDA_NORMAL,		/* normal http/http/ftp/mailto/etc link */
+	MKDA_EMAIL,			/* e-mail link without explit mailto: */
+};
+
+enum mkd_tableflags {
+	MKD_TABLE_ALIGN_L = 1,
+	MKD_TABLE_ALIGN_R = 2,
+	MKD_TABLE_ALIGN_CENTER = 3,
+	MKD_TABLE_ALIGNMASK = 3,
+	MKD_TABLE_HEADER = 4
+};
+
+enum mkd_extensions {
+	MKDEXT_NO_INTRA_EMPHASIS = (1 << 0),
+	MKDEXT_TABLES = (1 << 1),
+	MKDEXT_FENCED_CODE = (1 << 2),
+	MKDEXT_AUTOLINK = (1 << 3),
+	MKDEXT_STRIKETHROUGH = (1 << 4),
+	MKDEXT_SPACE_HEADERS = (1 << 6),
+	MKDEXT_SUPERSCRIPT = (1 << 7),
+	MKDEXT_LAX_SPACING = (1 << 8),
+};
+
+/* sd_callbacks - functions for rendering parsed data */
+struct sd_callbacks {
+	/* block level callbacks - NULL skips the block */
+	void (*blockcode)(struct buf *ob, const struct buf *text, const struct buf *lang, void *opaque);
+	void (*blockquote)(struct buf *ob, const struct buf *text, void *opaque);
+	void (*blockhtml)(struct buf *ob,const  struct buf *text, void *opaque);
+	void (*header)(struct buf *ob, const struct buf *text, int level, void *opaque);
+	void (*hrule)(struct buf *ob, void *opaque);
+	void (*list)(struct buf *ob, const struct buf *text, int flags, void *opaque);
+	void (*listitem)(struct buf *ob, const struct buf *text, int flags, void *opaque);
+	void (*paragraph)(struct buf *ob, const struct buf *text, void *opaque);
+	void (*table)(struct buf *ob, const struct buf *header, const struct buf *body, void *opaque);
+	void (*table_row)(struct buf *ob, const struct buf *text, void *opaque);
+	void (*table_cell)(struct buf *ob, const struct buf *text, int flags, void *opaque);
+
+
+	/* span level callbacks - NULL or return 0 prints the span verbatim */
+	int (*autolink)(struct buf *ob, const struct buf *link, enum mkd_autolink type, void *opaque);
+	int (*codespan)(struct buf *ob, const struct buf *text, void *opaque);
+	int (*double_emphasis)(struct buf *ob, const struct buf *text, void *opaque);
+	int (*emphasis)(struct buf *ob, const struct buf *text, void *opaque);
+	int (*image)(struct buf *ob, const struct buf *link, const struct buf *title, const struct buf *alt, void *opaque);
+	int (*linebreak)(struct buf *ob, void *opaque);
+	int (*link)(struct buf *ob, const struct buf *link, const struct buf *title, const struct buf *content, void *opaque);
+	int (*raw_html_tag)(struct buf *ob, const struct buf *tag, void *opaque);
+	int (*triple_emphasis)(struct buf *ob, const struct buf *text, void *opaque);
+	int (*strikethrough)(struct buf *ob, const struct buf *text, void *opaque);
+	int (*superscript)(struct buf *ob, const struct buf *text, void *opaque);
+
+	/* low level callbacks - NULL copies input directly into the output */
+	void (*entity)(struct buf *ob, const struct buf *entity, void *opaque);
+	void (*normal_text)(struct buf *ob, const struct buf *text, void *opaque);
+
+	/* header and footer */
+	void (*doc_header)(struct buf *ob, void *opaque);
+	void (*doc_footer)(struct buf *ob, void *opaque);
+};
+
+struct sd_markdown;
+
+/*********
+ * FLAGS *
+ *********/
+
+/* list/listitem flags */
+#define MKD_LIST_ORDERED	1
+#define MKD_LI_BLOCK		2  /* <li> containing block data */
+
+/**********************
+ * EXPORTED FUNCTIONS *
+ **********************/
+
+extern struct sd_markdown *
+sd_markdown_new(
+	unsigned int extensions,
+	size_t max_nesting,
+	const struct sd_callbacks *callbacks,
+	void *opaque);
+
+extern void
+sd_markdown_render(struct buf *ob, const uint8_t *document, size_t doc_size, struct sd_markdown *md);
+
+extern void
+sd_markdown_free(struct sd_markdown *md);
+
+extern void
+sd_version(int *major, int *minor, int *revision);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/* vim: set filetype=c: */
diff --git a/src/rt/sundown/src/stack.c b/src/rt/sundown/src/stack.c
new file mode 100644
index 0000000000000..ce069ff3b9d09
--- /dev/null
+++ b/src/rt/sundown/src/stack.c
@@ -0,0 +1,81 @@
+#include "stack.h"
+#include <string.h>
+
+int
+stack_grow(struct stack *st, size_t new_size)
+{
+	void **new_st;
+
+	if (st->asize >= new_size)
+		return 0;
+
+	new_st = realloc(st->item, new_size * sizeof(void *));
+	if (new_st == NULL)
+		return -1;
+
+	memset(new_st + st->asize, 0x0,
+		(new_size - st->asize) * sizeof(void *));
+
+	st->item = new_st;
+	st->asize = new_size;
+
+	if (st->size > new_size)
+		st->size = new_size;
+
+	return 0;
+}
+
+void
+stack_free(struct stack *st)
+{
+	if (!st)
+		return;
+
+	free(st->item);
+
+	st->item = NULL;
+	st->size = 0;
+	st->asize = 0;
+}
+
+int
+stack_init(struct stack *st, size_t initial_size)
+{
+	st->item = NULL;
+	st->size = 0;
+	st->asize = 0;
+
+	if (!initial_size)
+		initial_size = 8;
+
+	return stack_grow(st, initial_size);
+}
+
+void *
+stack_pop(struct stack *st)
+{
+	if (!st->size)
+		return NULL;
+
+	return st->item[--st->size];
+}
+
+int
+stack_push(struct stack *st, void *item)
+{
+	if (stack_grow(st, st->size * 2) < 0)
+		return -1;
+
+	st->item[st->size++] = item;
+	return 0;
+}
+
+void *
+stack_top(struct stack *st)
+{
+	if (!st->size)
+		return NULL;
+
+	return st->item[st->size - 1];
+}
+
diff --git a/src/rt/sundown/src/stack.h b/src/rt/sundown/src/stack.h
new file mode 100644
index 0000000000000..08ff030a33b0f
--- /dev/null
+++ b/src/rt/sundown/src/stack.h
@@ -0,0 +1,29 @@
+#ifndef STACK_H__
+#define STACK_H__
+
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct stack {
+	void **item;
+	size_t size;
+	size_t asize;
+};
+
+void stack_free(struct stack *);
+int stack_grow(struct stack *, size_t);
+int stack_init(struct stack *, size_t);
+
+int stack_push(struct stack *, void *);
+
+void *stack_pop(struct stack *);
+void *stack_top(struct stack *);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif