Merge pull request #929 from opensourcerouting/hooks-doc-irdp

hook improvements, more hooks, doc example, IRDP cleanup

7 files changed, 828 insertions, 0 deletions

diff --git a/doc/code/.gitignore b/doc/code/.gitignore
new file mode 100644
index 000000000..050553715
--- /dev/null
+++ b/doc/code/.gitignore
@@ -0,0 +1,3 @@
+/_templates
+/_build
+!/Makefile
diff --git a/doc/code/Makefile b/doc/code/Makefile
new file mode 100644
index 000000000..056b78e68
--- /dev/null
+++ b/doc/code/Makefile
@@ -0,0 +1,216 @@
+# Makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line.
+SPHINXOPTS    =
+SPHINXBUILD   = sphinx-build
+PAPER         =
+BUILDDIR      = _build
+
+# User-friendly check for sphinx-build
+ifeq ($(shell which $(SPHINXBUILD) >/dev/null 2>&1; echo $$?), 1)
+$(error The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed, then set the SPHINXBUILD environment variable to point to the full path of the '$(SPHINXBUILD)' executable. Alternatively you can add the directory with the executable to your PATH. If you don't have Sphinx installed, grab it from http://sphinx-doc.org/)
+endif
+
+# Internal variables.
+PAPEROPT_a4     = -D latex_paper_size=a4
+PAPEROPT_letter = -D latex_paper_size=letter
+ALLSPHINXOPTS   = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+# the i18n builder cannot share the environment and doctrees with the others
+I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+
+.PHONY: help
+help:
+	@echo "Please use \`make <target>' where <target> is one of"
+	@echo "  html       to make standalone HTML files"
+	@echo "  dirhtml    to make HTML files named index.html in directories"
+	@echo "  singlehtml to make a single large HTML file"
+	@echo "  pickle     to make pickle files"
+	@echo "  json       to make JSON files"
+	@echo "  htmlhelp   to make HTML files and a HTML help project"
+	@echo "  qthelp     to make HTML files and a qthelp project"
+	@echo "  applehelp  to make an Apple Help Book"
+	@echo "  devhelp    to make HTML files and a Devhelp project"
+	@echo "  epub       to make an epub"
+	@echo "  latex      to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
+	@echo "  latexpdf   to make LaTeX files and run them through pdflatex"
+	@echo "  latexpdfja to make LaTeX files and run them through platex/dvipdfmx"
+	@echo "  text       to make text files"
+	@echo "  man        to make manual pages"
+	@echo "  texinfo    to make Texinfo files"
+	@echo "  info       to make Texinfo files and run them through makeinfo"
+	@echo "  gettext    to make PO message catalogs"
+	@echo "  changes    to make an overview of all changed/added/deprecated items"
+	@echo "  xml        to make Docutils-native XML files"
+	@echo "  pseudoxml  to make pseudoxml-XML files for display purposes"
+	@echo "  linkcheck  to check all external links for integrity"
+	@echo "  doctest    to run all doctests embedded in the documentation (if enabled)"
+	@echo "  coverage   to run coverage check of the documentation (if enabled)"
+
+.PHONY: clean
+clean:
+	rm -rf $(BUILDDIR)/*
+
+.PHONY: html
+html:
+	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
+
+.PHONY: dirhtml
+dirhtml:
+	$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
+	@echo
+	@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
+
+.PHONY: singlehtml
+singlehtml:
+	$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
+	@echo
+	@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
+
+.PHONY: pickle
+pickle:
+	$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
+	@echo
+	@echo "Build finished; now you can process the pickle files."
+
+.PHONY: json
+json:
+	$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
+	@echo
+	@echo "Build finished; now you can process the JSON files."
+
+.PHONY: htmlhelp
+htmlhelp:
+	$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
+	@echo
+	@echo "Build finished; now you can run HTML Help Workshop with the" \
+	      ".hhp project file in $(BUILDDIR)/htmlhelp."
+
+.PHONY: qthelp
+qthelp:
+	$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
+	@echo
+	@echo "Build finished; now you can run "qcollectiongenerator" with the" \
+	      ".qhcp project file in $(BUILDDIR)/qthelp, like this:"
+	@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/FRR.qhcp"
+	@echo "To view the help file:"
+	@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/FRR.qhc"
+
+.PHONY: applehelp
+applehelp:
+	$(SPHINXBUILD) -b applehelp $(ALLSPHINXOPTS) $(BUILDDIR)/applehelp
+	@echo
+	@echo "Build finished. The help book is in $(BUILDDIR)/applehelp."
+	@echo "N.B. You won't be able to view it unless you put it in" \
+	      "~/Library/Documentation/Help or install it in your application" \
+	      "bundle."
+
+.PHONY: devhelp
+devhelp:
+	$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
+	@echo
+	@echo "Build finished."
+	@echo "To view the help file:"
+	@echo "# mkdir -p $$HOME/.local/share/devhelp/FRR"
+	@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/FRR"
+	@echo "# devhelp"
+
+.PHONY: epub
+epub:
+	$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
+	@echo
+	@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
+
+.PHONY: latex
+latex:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo
+	@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
+	@echo "Run \`make' in that directory to run these through (pdf)latex" \
+	      "(use \`make latexpdf' here to do that automatically)."
+
+.PHONY: latexpdf
+latexpdf:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo "Running LaTeX files through pdflatex..."
+	$(MAKE) -C $(BUILDDIR)/latex all-pdf
+	@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
+
+.PHONY: latexpdfja
+latexpdfja:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
+	@echo "Running LaTeX files through platex and dvipdfmx..."
+	$(MAKE) -C $(BUILDDIR)/latex all-pdf-ja
+	@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
+
+.PHONY: text
+text:
+	$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
+	@echo
+	@echo "Build finished. The text files are in $(BUILDDIR)/text."
+
+.PHONY: man
+man:
+	$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
+	@echo
+	@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
+
+.PHONY: texinfo
+texinfo:
+	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
+	@echo
+	@echo "Build finished. The Texinfo files are in $(BUILDDIR)/texinfo."
+	@echo "Run \`make' in that directory to run these through makeinfo" \
+	      "(use \`make info' here to do that automatically)."
+
+.PHONY: info
+info:
+	$(SPHINXBUILD) -b texinfo $(ALLSPHINXOPTS) $(BUILDDIR)/texinfo
+	@echo "Running Texinfo files through makeinfo..."
+	make -C $(BUILDDIR)/texinfo info
+	@echo "makeinfo finished; the Info files are in $(BUILDDIR)/texinfo."
+
+.PHONY: gettext
+gettext:
+	$(SPHINXBUILD) -b gettext $(I18NSPHINXOPTS) $(BUILDDIR)/locale
+	@echo
+	@echo "Build finished. The message catalogs are in $(BUILDDIR)/locale."
+
+.PHONY: changes
+changes:
+	$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
+	@echo
+	@echo "The overview file is in $(BUILDDIR)/changes."
+
+.PHONY: linkcheck
+linkcheck:
+	$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
+	@echo
+	@echo "Link check complete; look for any errors in the above output " \
+	      "or in $(BUILDDIR)/linkcheck/output.txt."
+
+.PHONY: doctest
+doctest:
+	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
+	@echo "Testing of doctests in the sources finished, look at the " \
+	      "results in $(BUILDDIR)/doctest/output.txt."
+
+.PHONY: coverage
+coverage:
+	$(SPHINXBUILD) -b coverage $(ALLSPHINXOPTS) $(BUILDDIR)/coverage
+	@echo "Testing of coverage in the sources finished, look at the " \
+	      "results in $(BUILDDIR)/coverage/python.txt."
+
+.PHONY: xml
+xml:
+	$(SPHINXBUILD) -b xml $(ALLSPHINXOPTS) $(BUILDDIR)/xml
+	@echo
+	@echo "Build finished. The XML files are in $(BUILDDIR)/xml."
+
+.PHONY: pseudoxml
+pseudoxml:
+	$(SPHINXBUILD) -b pseudoxml $(ALLSPHINXOPTS) $(BUILDDIR)/pseudoxml
+	@echo
+	@echo "Build finished. The pseudo-XML files are in $(BUILDDIR)/pseudoxml."
diff --git a/doc/code/conf.py b/doc/code/conf.py
new file mode 100644
index 000000000..38be7f2fc
--- /dev/null
+++ b/doc/code/conf.py
@@ -0,0 +1,293 @@
+# -*- coding: utf-8 -*-
+#
+# FRR documentation build configuration file, created by
+# sphinx-quickstart on Tue Jan 31 16:00:52 2017.
+#
+# This file is execfile()d with the current directory set to its
+# containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+import sys
+import os
+import re
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#sys.path.insert(0, os.path.abspath('.'))
+
+# -- General configuration ------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+#needs_sphinx = '1.0'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = ['sphinx.ext.todo']
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+# source_suffix = ['.rst', '.md']
+source_suffix = '.rst'
+
+# The encoding of source files.
+#source_encoding = 'utf-8-sig'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = u'FRR'
+copyright = u'2017, FRR'
+author = u'FRR'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+
+# The short X.Y version.
+version = u'?.?'
+# The full version, including alpha/beta/rc tags.
+release = u'?.?-?'
+
+val = re.compile('^S\["([^"]+)"\]="(.*)"$')
+with open('../../config.status', 'r') as cfgstatus:
+    for ln in cfgstatus.readlines():
+        m = val.match(ln)
+        if m is None: continue
+        if m.group(1) == 'PACKAGE_VERSION':
+            release = m.group(2)
+            version = release.split('-')[0]
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+#today = ''
+# Else, today_fmt is used as the format for a strftime call.
+#today_fmt = '%B %d, %Y'
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+exclude_patterns = ['_build']
+
+# The reST default role (used for this markup: `text`) to use for all
+# documents.
+#default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+#add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+#add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+#show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+#modindex_common_prefix = []
+
+# If true, keep warnings as "system message" paragraphs in the built documents.
+#keep_warnings = False
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = True
+
+
+# -- Options for HTML output ----------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+html_theme = 'sphinx_rtd_theme'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#html_theme_options = {}
+
+# Add any paths that contain custom themes here, relative to this directory.
+#html_theme_path = []
+
+# The name for this set of Sphinx documents.  If None, it defaults to
+# "<project> v<release> documentation".
+#html_title = None
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+#html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+#html_logo = None
+
+# The name of an image file (within the static path) to use as favicon of the
+# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+#html_favicon = None
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# Add any extra paths that contain custom files (such as robots.txt or
+# .htaccess) here, relative to this directory. These files are copied
+# directly to the root of the documentation.
+#html_extra_path = []
+
+# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
+# using the given strftime format.
+#html_last_updated_fmt = '%b %d, %Y'
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+#html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+#html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+#html_additional_pages = {}
+
+# If false, no module index is generated.
+#html_domain_indices = True
+
+# If false, no index is generated.
+#html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+#html_split_index = False
+
+# If true, links to the reST sources are added to the pages.
+#html_show_sourcelink = True
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+#html_show_sphinx = True
+
+# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
+#html_show_copyright = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+#html_use_opensearch = ''
+
+# This is the file name suffix for HTML files (e.g. ".xhtml").
+#html_file_suffix = None
+
+# Language to be used for generating the HTML full-text search index.
+# Sphinx supports the following languages:
+#   'da', 'de', 'en', 'es', 'fi', 'fr', 'hu', 'it', 'ja'
+#   'nl', 'no', 'pt', 'ro', 'ru', 'sv', 'tr'
+#html_search_language = 'en'
+
+# A dictionary with options for the search language support, empty by default.
+# Now only 'ja' uses this config value
+#html_search_options = {'type': 'default'}
+
+# The name of a javascript file (relative to the configuration directory) that
+# implements a search results scorer. If empty, the default will be used.
+#html_search_scorer = 'scorer.js'
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'FRRdoc'
+
+# -- Options for LaTeX output ---------------------------------------------
+
+latex_elements = {
+# The paper size ('letterpaper' or 'a4paper').
+#'papersize': 'letterpaper',
+
+# The font size ('10pt', '11pt' or '12pt').
+#'pointsize': '10pt',
+
+# Additional stuff for the LaTeX preamble.
+#'preamble': '',
+
+# Latex figure (float) alignment
+#'figure_align': 'htbp',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+latex_documents = [
+    (master_doc, 'FRR.tex', u'FRR Documentation',
+     u'FRR', 'manual'),
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+#latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+#latex_use_parts = False
+
+# If true, show page references after internal links.
+#latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+#latex_show_urls = False
+
+# Documents to append as an appendix to all manuals.
+#latex_appendices = []
+
+# If false, no module index is generated.
+#latex_domain_indices = True
+
+
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, 'frr', u'FRR Documentation',
+     [author], 1)
+]
+
+# If true, show URL addresses after external links.
+#man_show_urls = False
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    (master_doc, 'FRR', u'FRR Documentation',
+     author, 'FRR', 'One line description of project.',
+     'Miscellaneous'),
+]
+
+# Documents to append as an appendix to all manuals.
+#texinfo_appendices = []
+
+# If false, no module index is generated.
+#texinfo_domain_indices = True
+
+# How to display URL addresses: 'footnote', 'no', or 'inline'.
+#texinfo_show_urls = 'footnote'
+
+# If true, do not generate a @detailmenu in the "Top" node's menu.
+#texinfo_no_detailmenu = False
diff --git a/doc/code/hooks.rst b/doc/code/hooks.rst
new file mode 100644
index 000000000..0afa297aa
--- /dev/null
+++ b/doc/code/hooks.rst
@@ -0,0 +1,171 @@
+.. highlight:: c
+
+Hooks
+=====
+
+Libfrr provides type-safe subscribable hook points where other pieces of
+code can add one or more callback functions.  "type-safe" in this case
+applies to the function pointers used for subscriptions.  The
+implementations checks (at compile-time) wheter a callback to be added has
+the appropriate function signature (parameters) for the hook.
+
+Example:
+
+.. code-block:: c
+     :caption: mydaemon.h
+
+     #include "hook.h"
+     DECLARE_HOOK(some_update_event, (struct eventinfo *info), (info))
+
+.. code-block:: c
+     :caption: mydaemon.c
+
+     #include "mydaemon.h"
+     DEFINE_HOOK(some_update_event, (struct eventinfo *info), (info))
+     ...
+     hook_call(some_update_event, info);
+
+.. code-block:: c
+     :caption: mymodule.c
+
+     #include "mydaemon.h"
+     static int event_handler(struct eventinfo *info);
+     ...
+     hook_register(some_update_event, event_handler);
+
+Do not use parameter names starting with "hook", these can collide with
+names used by the hook code itself.
+
+
+Return values
+-------------
+
+Callbacks to be placed on hooks always return "int" for now;  hook_call will
+sum up the return values from each called function.  (The default is 0 if no
+callbacks are registered.)
+
+There are no pre-defined semantics for the value, in most cases it is
+ignored.  For success/failure indication, 0 should be success, and
+handlers should make sure to only return 0 or 1 (not -1 or other values).
+
+There is no built-in way to abort executing a chain after a failure of one
+of the callbacks.  If this is needed, the hook can use an extra
+``bool *aborted`` argument.
+
+
+Priorities
+----------
+
+Hooks support a "priority" value for ordering registered calls
+relative to each other.  The priority is a signed integer where lower
+values are called earlier.  There are also "Koohs", which is hooks with
+reverse priority ordering (for cleanup/deinit hooks, so you can use the
+same priority value).
+
+Recommended priority value ranges are:
+
+======================== ===================================================
+Range                    Usage
+------------------------ ---------------------------------------------------
+ -999 ...     0 ...  999 main executable / daemon, or library
+
+-1999 ... -1000          modules registering calls that should run before
+                         the daemon's bits
+
+1000 ... 1999            modules' calls that should run after daemon's
+                         (includes default value: 1000)
+======================== ===================================================
+
+Note: the default value is 1000, based on the following 2 expectations:
+
+- most hook_register() usage will be in loadable modules
+- usage of hook_register() in the daemon itself may need relative ordering
+  to itself, making an explicit value the expected case
+
+The priority value is passed as extra argument on hook_register_prio() /
+hook_register_arg_prio().  Whether a hook runs in reverse is determined
+solely by the code defining / calling the hook.  (DECLARE_KOOH is actually
+the same thing as DECLARE_HOOK, it's just there to make it obvious.)
+
+
+Definition
+----------
+
+.. c:macro:: DECLARE_HOOK(name, arglist, passlist)
+.. c:macro:: DECLARE_KOOH(name, arglist, passlist)
+
+   :param name: Name of the hook to be defined
+   :param arglist: Function definition style parameter list in braces.
+   :param passlist: List of the same parameters without their types.
+
+   Note:  the second and third macro args must be the hook function's
+   parameter list, with the same names for each parameter.  The second
+   macro arg is with types (used for defining things), the third arg is
+   just the names (used for passing along parameters).
+
+   This macro must be placed in a header file;  this header file must be
+   included to register a callback on the hook.
+
+   Examples:
+
+   .. code-block:: c
+
+      DECLARE_HOOK(foo, (), ())
+      DECLARE_HOOK(bar, (int arg), (arg))
+      DECLARE_HOOK(baz, (const void *x, in_addr_t y), (x, y))
+
+.. c:macro:: DEFINE_HOOK(name, arglist, passlist)
+
+   Implements an hook.  Each ``DECLARE_HOOK`` must have be accompanied by
+   exactly one ``DEFINE_HOOK``, which needs to be placed in a source file.
+   **The hook can only be called from this source file.**  This is intentional
+   to avoid overloading and/or misusing hooks for distinct purposes.
+
+   The compiled source file will include a global symbol with the name of the
+   hook prefixed by `_hook_`.  Trying to register a callback for a hook that
+   doesn't exist will therefore result in a linker error, or a module
+   load-time error for dynamic modules.
+
+.. c:macro:: DEFINE_KOOH(name, arglist, passlist)
+
+   Same as ``DEFINE_HOOK``, but the sense of priorities / order of callbacks
+   is reversed.  This should be used for cleanup hooks.
+
+.. c:function:: int hook_call(name, ...)
+
+   Calls the specified named hook.  Parameters to the hook are passed right
+   after the hook name, e.g.:
+
+   .. code-block:: c
+
+      hook_call(foo);
+      hook_call(bar, 0);
+      hook_call(baz, NULL, INADDR_ANY);
+
+   Returns the sum of return values from all callbacks.  The ``DEFINE_HOOK``
+   statement for the hook must be placed in the file before any ``hook_call``
+   use of the hook.
+
+
+Callback registration
+---------------------
+
+.. c:function:: void hook_register(name, int (*callback)(...))
+.. c:function:: void hook_register_prio(name, int priority, int (*callback)(...))
+.. c:function:: void hook_register_arg(name, int (*callback)(void *arg, ...), void *arg)
+.. c:function:: void hook_register_arg_prio(name, int priority, int (*callback)(void *arg, ...), void *arg)
+
+   Register a callback with an hook.  If the caller needs to pass an extra
+   argument to the callback, the _arg variant can be used and the extra
+   parameter will be passed as first argument to the callback.  There is no
+   typechecking for this argument.
+
+   The priority value is used as described above.  The variants without a
+   priority parameter use 1000 as priority value.
+
+.. c:function:: void hook_unregister(name, int (*callback)(...))
+.. c:function:: void hook_unregister_arg(name, int (*callback)(void *arg, ...), void *arg)
+
+   Removes a previously registered callback from a hook.  Note that there
+   is no _prio variant of these calls.  The priority value is only used during
+   registration.
diff --git a/doc/code/index.rst b/doc/code/index.rst
new file mode 100644
index 000000000..79647d0b9
--- /dev/null
+++ b/doc/code/index.rst
@@ -0,0 +1,18 @@
+Welcome to FRR's documentation!
+===============================
+
+Contents:
+
+.. toctree::
+   :maxdepth: 2
+
+   library
+
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`
+
diff --git a/doc/code/library.rst b/doc/code/library.rst
new file mode 100644
index 000000000..dd46021db
--- /dev/null
+++ b/doc/code/library.rst
@@ -0,0 +1,10 @@
+libfrr library facilities
+=========================
+
+.. toctree::
+   :maxdepth: 2
+
+   memtypes
+   hooks
+
+
diff --git a/doc/code/memtypes.rst b/doc/code/memtypes.rst
new file mode 100644
index 000000000..62d211e86
--- /dev/null
+++ b/doc/code/memtypes.rst
@@ -0,0 +1,117 @@
+.. highlight:: c
+
+Memtypes
+========
+
+FRR includes wrappers arround ``malloc()`` and ``free()`` that count the number
+of objects currently allocated, for each of a defined ``MTYPE``.
+
+To this extent, there are `memory groups` and `memory types`.  Each memory
+type must belong to a memory group, this is used just to provide some basic
+structure.
+
+Example:
+
+.. code-block:: c
+     :caption: mydaemon.h
+
+     DECLARE_MGROUP(MYDAEMON)
+     DECLARE_MTYPE(MYNEIGHBOR)
+
+.. code-block:: c
+     :caption: mydaemon.c
+
+     DEFINE_MGROUP(      MYDAEMON, "My daemon's memory")
+     DEFINE_MTYPE(       MYDAEMON, MYNEIGHBOR,     "Neighbor entry")
+     DEFINE_MTYPE_STATIC(MYDAEMON, MYNEIGHBORNAME, "Neighbor name")
+
+     struct neigh *neighbor_new(const char *name)
+     {
+        struct neigh *n = XMALLOC(MYNEIGHBOR, sizeof(*n));
+        n->name = XSTRDUP(MYNEIGHBORNAME, name);
+        return n;
+     }
+
+     void neighbor_free(struct neigh *n)
+     {
+        XFREE(MYNEIGHBORNAME, n->name);
+        XFREE(MYNEIGHBOR, n);
+     }
+
+
+Definition
+----------
+
+.. c:macro:: DECLARE_MGROUP(name)
+
+   This macro forward-declares a memory group and should be placed in a
+   ``.h`` file.  It expands to an ``extern struct memgroup`` statement.
+
+.. c:macro:: DEFINE_MGROUP(mname, description)
+
+   Defines/implements a memory group.  Must be placed into exactly one ``.c``
+   file (multiple inclusion will result in a link-time symbol conflict).
+
+   Contains additional logic (constructor and destructor) to register the
+   memory group in a global list.
+
+.. c:macro:: DECLARE_MTYPE(name)
+
+   Forward-declares a memory type and makes ``MTYPE_name`` available for use.
+   Note that the ``MTYPE_`` prefix must not be included in the name, it is
+   automatically prefixed.
+
+   ``MTYPE_name`` is created as a `static const` symbol, i.e. a compile-time
+   constant.  It refers to an ``extern struct memtype _mt_name``, where `name`
+   is replaced with the actual name.
+
+.. c:macro:: DEFINE_MTYPE(group, name, description)
+
+   Define/implement a memory type, must be placed into exactly one ``.c``
+   file (multiple inclusion will result in a link-time symbol conflict).
+
+   Like ``DEFINE_MGROUP``, this contains actual code to register the MTYPE
+   under its group.
+
+.. c:macro:: DEFINE_MTYPE_STATIC(group, name, description)
+
+   Same as ``DEFINE_MTYPE``, but the ``DEFINE_MTYPE_STATIC`` variant places
+   the C ``static`` keyword on the definition, restricting the MTYPE's
+   availability to the current source file.  This should be appropriate in
+   >80% of cases.
+
+   .. todo::
+   
+      Daemons currently have ``daemon_memory.[ch]`` files listing all of
+      their MTYPEs.  This is not how it should be, most of these types
+      should be moved into the appropriate files where they are used.
+      Only a few MTYPEs should remain non-static after that.
+
+
+Usage
+-----
+
+.. c:function:: void *XMALLOC(struct memtype *mtype, size_t size)
+
+.. c:function:: void *XCALLOC(struct memtype *mtype, size_t size)
+
+.. c:function:: void *XSTRDUP(struct memtype *mtype, size_t size)
+
+   Allocation wrappers for malloc/calloc/realloc/strdup, taking an extra
+   mtype parameter.
+
+.. c:function:: void *XREALLOC(struct memtype *mtype, void *ptr, size_t size)
+
+   Wrapper around realloc() with MTYPE tracking.  Note that ``ptr`` may
+   be NULL, in which case the function does the same as XMALLOC (regardless
+   of whether the system realloc() supports this.)
+
+.. c:function:: void XFREE(struct memtype *mtype, void *ptr)
+
+   Wrapper around free(), again taking an extra mtype parameter.  This is
+   actually a macro, with the following additional properties:
+
+   - the macro contains ``ptr = NULL``
+   - if ptr is NULL, no operation is performed (as is guaranteed by system
+     implementations.)  Do not surround XFREE with ``if (ptr != NULL)``
+     checks.