13 files changed, 580 insertions, 55 deletions
diff --git a/build-aux/Makefile.once.head/00-gitfiles.mk b/build-aux/Makefile.once.head/00-gitfiles.mk
new file mode 100644
index 0000000..dbb4ae9
--- /dev/null
+++ b/build-aux/Makefile.once.head/00-gitfiles.mk
@@ -0,0 +1,74 @@
+# Copyright (C) 2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.gitfiles.description = Automatically populate files.src.src from git
+mod.gitfiles.depends += files nested write-ifchanged quote
+mod.gitfiles.files += $(topsrcdir)/$(gitfiles.file)
+define mod.gitfiles.doc
+# Inputs:
+#   - Global variable    : `gitfiles.file` (Default: gitfiles.mk)
+#   - Directory variable : `nested.subdirs`
+#   - External           : git
+# Outputs:
+#   - File               : `$(topsrcdir)/$(gitfiles.file)`
+#   - Directory variable : `files.src.src`
+#   - Directory variable : `files.src.gen` (only in top dir)
+#
+# The `files` module has a variable (`files.src.src`) that you (the
+# developer) set to list "pure" source files; the type of files that you
+# would check into a version control system.  Since you are a
+# responsible developer, you use a version control system.  Since the
+# computer is already maintaining a list of these files *in the VCS*,
+# why should you--a filthy human--need to also maintain the list?  Enter
+# gitfiles, which will talk to git to maintain `files.src.src`, but
+# won't require that the git repository be distributed to
+# installing-users.
+#
+# If `$(topsrcdir)/.git` exists, then it will generate
+# `$(topsrcdir)/$(gitfiles.file)`.  Otherwise, it will assume that
+# `$(topsrcdir)/$(gitfiles.file)` already exists.
+#
+# It will use the information in `$(topsrcdir)/$(gitfiles.file)` to
+# append to `files.src.src` in each directory
+#
+# Finally, since the generated `$(topsrcdir)/$(gitfiles.file)` must be
+# distributed to users, it is added to $(topsrcdirs)'s `files.src.gen`.
+#
+# When setting `files.src.src`, it needs to know which files "belong" to
+# the current directory directly, and which "belong" to a further
+# subdirectory.  To do this, it uses an expression involving
+# `$(nested.subdirs)`.
+#
+# While gitfiles sets `files.src.src` very early in `each.head`, because
+# `nested.subdirs` might not be set yet, it may or may not be safe to
+# use the value of `$(files.src.src)` in your Makefile, depending on how
+# you set `nested.subdirs`.
+endef
+mod.gitfiles.doc := $(value mod.gitfiles.doc)
+
+gitfiles.file ?= gitfiles.mk
+
+_gitfiles.all =
+-include $(topsrcdir)/$(gitfiles.file)
+
+ifneq ($(wildcard $(topsrcdir)/.git),)
+$(topsrcdir)/$(gitfiles.file): _gitfiles.FORCE
+	@(cd $(@D) && git ls-files -z) | sed -z -e 's/\$$/\$$$$/g' -e 's/\n/$$(at.nl)/g' | xargs -r0 printf '_gitfiles.all+=%s\n' | $(WRITE_IFCHANGED) $@
+.PHONY: _gitfiles.FORCE
+endif
+
+_gitfiles.dir = $(call at.relto,$(topsrcdir),$(srcdir))
+_gitfiles.dir.all = $(patsubst $(_gitfiles.dir)/%,%,$(filter $(_gitfiles.dir)/%,$(_gitfiles.all)))
+_gitfiles.dir.src = $(filter-out $(addsuffix /%,$(nested.subdirs)),$(_gitfiles.dir.all))
diff --git a/build-aux/Makefile.once.head/00-quote.mk b/build-aux/Makefile.once.head/00-quote.mk
new file mode 100644
index 0000000..94bc943
--- /dev/null
+++ b/build-aux/Makefile.once.head/00-quote.mk
@@ -0,0 +1,49 @@
+# Copyright (C) 2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.quote.description = Macros to quote tricky strings
+define mod.quote.doc
+# Inputs:
+#   (none)
+# Outputs:
+#   - Global variable: `quote.var`       : GNU Make variables
+#   - Global variable: `quote.pattern`   : GNU Make patterns
+#   - Global variable: `quote.ere`       : POSIX Extended Regular Expressions
+#   - Global variable: `quote.bre`       : POSIX Basic Regular Expressions
+#   - Global variable: `quote.shell`     : POSIX sh(1) strings
+#   - Global variable: `quote.shell-each`: POSIX sh(1) strings
+#
+# Escaping/quoting things is hard!  This module provides a number of
+# functions to escape/quote strings for various contexts.
+#
+# `quote.shell-each` quotes each list-item separately (munging
+# whitespace), while `quote.shell` keeps them as one string (preserving
+# whitespace).
+endef
+mod.quote.doc := $(value mod.quote.doc)
+
+_quote.backslash = $(if $1,$(call _quote.backslash,$(wordlist 2,$(words $1),$1),$(subst $(firstword $1),\$(firstword $1),$2)),$2)
+
+quote.var     = $(subst $(at.nl),\$(at.nl),$(subst $$,$$$$,$1))
+quote.pattern = $(call _quote.backslash, \ % ,$1)
+quote.ere     = $(call _quote.backslash, \ ^ . [ $$ ( ) | * + ? { ,$1)
+quote.bre     = $(call _quote.backslash, \ ^ . [ $$       *       ,$1)
+
+quote.shell-each = $(foreach _quote.tmp,$1,$(call quote.shell,$(_quote.tmp)))
+
+# I put this as the last line in the file because it confuses Emacs
+# syntax highlighting and makes the remainder of the file difficult to
+# edit.
+quote.shell = $(subst $(at.nl),'$$'\n'','$(subst ','\'',$1)')
diff --git a/build-aux/Makefile.once.head/00-var.mk b/build-aux/Makefile.once.head/00-var.mk
new file mode 100644
index 0000000..1f50f21
--- /dev/null
+++ b/build-aux/Makefile.once.head/00-var.mk
@@ -0,0 +1,33 @@
+# Copyright (C) 2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.var.description = Depend on the values of variables
+define mod.var.doc
+# Inputs:
+#   (user-defined)
+# Outputs:
+#   Target            : `$(outdir)/.var.%`
+#   Directory variable: `at.targets`
+#
+# It's a well-known secret that many files generated by a Makefile vary with
+# the values of particular variables, but that GNU Make can't track these
+# dependencies.  Well, with some cleverness, it actually can!
+#
+# With this module, to depend on the value of a variable, depend on
+# `$(outdir)/.var.VARNAME`.
+endef
+mod.var.doc := $(value mod.var.doc)
+
+.PHONY: _var.FORCE
diff --git a/build-aux/Makefile.once.head/00-write-ifchanged.mk b/build-aux/Makefile.once.head/00-write-ifchanged.mk
deleted file mode 100644
index 79ef1c4..0000000
--- a/build-aux/Makefile.once.head/00-write-ifchanged.mk
+++ /dev/null
@@ -1 +0,0 @@
-WRITE_IFCHANGED = $(topsrcdir)/build-aux/write-ifchanged
diff --git a/build-aux/Makefile.once.head/10-dist.mk b/build-aux/Makefile.once.head/10-dist.mk
new file mode 100644
index 0000000..27b39ec
--- /dev/null
+++ b/build-aux/Makefile.once.head/10-dist.mk
@@ -0,0 +1,79 @@
+# Copyright (C) 2015-2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.dist.description = `dist` target to create distribution tarballs
+define mod.dist.doc
+# User variables:
+#   - `CP      ?= cp`
+#   - `GZIP    ?= gzip`
+#   - `MKDIR   ?= mkdir`
+#   - `MKDIR_P ?= mkdir -p`
+#   - `MV      ?= mv`
+#   - `RM      ?= rm -f`
+#   - `TAR     ?= tar`
+#   - `GZIPFLAGS ?= $(GZIP_ENV)`
+#   - `GZIP_ENV ?= --best` (only used via `GZIPFLAGS`, not directly)
+# Inputs:
+#   - Global variable    : `dist.exts`    (Default: `.tar.gz`)
+#   - Global variable    : `dist.pkgname` (Default: first of PACKAGE_TARNAME PACKAGE PACKAGE_NAME)
+#   - Global variable    : `dist.version` (Default: first of PACKAGE_VERSION VERSION)
+#   - Directory variable : `files.src`
+# Outputs:
+#   - Directory variable : `files.out.int` (only in top dir)
+#   - .PHONY Target      : `$(outdir)/dist`
+#   - Target             : `$(topoutdir)/$(dist.pkgname)-$(dist.version)`
+#   - Target             : `$(topoutdir)/$(dist.pkgname)-$(dist.version).tar`
+#   - Target             : `$(topoutdir)/$(dist.pkgname)-$(dist.version).tar.gz`
+#
+# Provide the standard `dist` .PHONY target, based on the `files` module
+# information.
+#
+# You may change the default compression target easily via the
+# `dist.exts` variable, but you must define the rule for it manually.
+#
+# Bugs:
+#
+#   The tarball isn't reproducible.  It uses file-system ordering of
+#   files, and includes timestamps.
+endef
+mod.dist.doc := $(value mod.dist.doc)
+
+# Developer configuration
+
+dist.exts ?= .tar.gz
+dist.pkgname ?= $(firstword $(PACKAGE_TARNAME) $(PACKAGE) $(PACKAGE_NAME))
+dist.version ?= $(firstword $(PACKAGE_VERSION) $(VERSION))
+
+ifeq ($(dist.pkgname),)
+$(error Autothing module: dist: dist.pkgname must be set)
+endif
+ifeq ($(dist.version),)
+$(error Autothing module: dist: dist.version must be set)
+endif
+
+_dist.files =
+
+# User configuration
+
+CP      ?= cp
+GZIP    ?= gzip
+MKDIR   ?= mkdir
+MKDIR_P ?= mkdir -p
+MV      ?= mv
+RM      ?= rm -f
+TAR     ?= tar
+
+GZIPFLAGS ?= $(GZIP_ENV)
+GZIP_ENV ?= --best
diff --git a/build-aux/Makefile.once.head/10-files.mk b/build-aux/Makefile.once.head/10-files.mk
new file mode 100644
index 0000000..f6fcf30
--- /dev/null
+++ b/build-aux/Makefile.once.head/10-files.mk
@@ -0,0 +1,87 @@
+# Copyright (C) 2015-2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.files.description = Keeping track of groups of files
+mod.files.depends += nested
+define mod.files.doc
+# User variables:
+#   - `DESTDIR ?=`
+#   - `RM      ?= rm -f`
+#   - `RMDIR_P ?= rmdir -p --ignore-fail-on-non-empty`
+#   - `TRUE    ?= true`
+# Inputs:
+#   - Global variable    : `files.groups   ?= all`
+#   - Global variable    : `files.default  ?= all`
+#   - Global variable    : `files.vcsclean ?= files.vcsclean`
+#   - Global variable    : `files.generate ?= files.generate`
+#   - Directory variable : `files.src.src`
+#   - Directory variable : `files.src.int`
+#   - Directory variable : `files.src.cfg`
+#   - Directory variable : `files.src.gen`
+#   - Directory variable : `files.out.slow`
+#   - Directory variable : `files.out.int`
+#   - Directory variable : `files.out.cfg`
+#   - Directory variable : `files.out.$(files.groups)` (well, $(addprefix...))
+#   - Directory variable : `files.sys.$(files.groups)` (well, $(addprefix...))
+# Outputs:
+#   - Global variable    : `nested.targets`
+#   - Global variable    : `at.targets`
+#   - Global variable    : `.DEFAULT_GOAL = $(files.default)`
+#   - Directory variable : `files.src`
+#   - Directory variable : `files.out`
+#   - Directory variable : `files.sys`
+#   - Creative .PHONY targets:
+#     - `$(outdir)/$(files.generate))`
+#     - `$(outdir)/$(group)` for `group` in `$(files.groups)`
+#     - `$(outdir)/install`
+#     - `$(outdir)/install-$(group)` for `group` in `$(filter-out $(files.default),$(files.groups))`
+#     - `$(outdir)/installdirs`
+#   - Destructive .PHONY targets:
+#     - `$(outdir)/uninstall`
+#     - `$(outdir)/mostlyclean`
+#     - `$(outdir)/clean`
+#     - `$(outdir)/distclean`
+#     - `$(outdir)/maintainer-clean`
+#     - `$(outdir)/$(files.vcsclean)`
+#
+# Basic `*` wildcards are supported.  Use `*`, not `%`; it will automatically
+# substitute `*`->`%` where appropriate.
+#
+# TODO: prose documentation
+endef
+mod.files.doc := $(value mod.files.doc)
+
+files.groups ?= all
+files.default ?= all
+files.vcsclean ?= files.vcsclean
+files.generate ?= files.generate
+
+.DEFAULT_GOAL = $(files.default)
+
+# Standard creative PHONY targets
+nested.targets += $(files.generate)
+nested.targets += install installdirs
+nested.targets += $(foreach g,$(files.groups),$g)
+nested.targets += $(foreach g,$(filter-out $(files.default),$(files.groups)),install-$g install-$gdirs)
+# Standard destructive PHONY targets
+nested.targets += uninstall mostlyclean clean distclean maintainer-clean
+
+# User configuration
+
+DESTDIR ?=
+
+RM      ?= rm -f
+RMDIR_P ?= rmdir -p --ignore-fail-on-non-empty
+TRUE    ?= true
diff --git a/build-aux/Makefile.once.head/00-gnuconf.mk b/build-aux/Makefile.once.head/10-gnuconf.mk
index 83cb110..e24dfa1 100644
--- a/build-aux/Makefile.once.head/00-gnuconf.mk
+++ b/build-aux/Makefile.once.head/10-gnuconf.mk
@@ -1,4 +1,4 @@
-# Copyright (C) 2016  Luke Shumaker
+# Copyright (C) 2016-2017  Luke Shumaker
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
@@ -13,12 +13,26 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# This file is based on §7.2 "Makefile Conventions" of the release of
-# the GNU Coding Standards dated April 13, 2016.
+mod.gnuconf.description = GNU standard configuration variables
+define mod.gnuconf.doc
+# Inputs:
+#   - Global variable: `gnuconf.pkgname`
+#      (Default: `$(firstword $(PACKAGE_TARNAME) $(PACKAGE) $(PACKAGE_NAME))`)
+# Outputs:
+#   (see below)
+#
+# This module defines default values (using `?=`) a huge list of
+# variables specified in the GNU Coding Standards that installing-users
+# expect to be able to set.
+#
+# This is based on §7.2 "Makefile Conventions" of the July 25, 2016
+# release of the GNU Coding Standards.
+endef
+mod.gnuconf.doc := $(value mod.gnuconf.doc)
 
 gnuconf.pkgname ?= $(firstword $(PACKAGE_TARNAME) $(PACKAGE) $(PACKAGE_NAME))
 ifeq ($(gnuconf.pkgname),)
-$(error gnuconf.pkgname must be set)
+$(error Autothing module: gnuconf: gnuconf.pkgname must be set)
 endif
 
 # 7.2.2: Utilities in Makefiles
@@ -54,43 +68,71 @@ TOUCH ?= touch
 TR ?= tr
 TRUE ?= true
 
-# These must be user-configurable
+# 7.2.2: Utilities in Makefiles/7.2.3: Variables for Specifying Commands
+# ----------------------------------------------------------------------
+
+# Standard user-configurable programs.
+#
+# The list of programs here is specified in §7.2.2, but the associated FLAGS
+# variables are specified in §7.2.3.  I found it cleaner to list them together.
 AR ?= ar
 ARFLAGS ?=
 BISON ?= bison
 BISONFLAGS ?=
 CC ?= cc
-CCFLAGS ?= $(CFLAGS)
+CFLAGS ?= # CFLAGS instead of CCFLAGS
 FLEX ?= flex
 FLEXFLAGS ?=
 INSTALL ?= install
-#INSTALLFLAGS ?=
+# There is no INSTALLFLAGS[0]
 LD ?= ld
 LDFLAGS ?=
-LDCONFIG ?= ldconfig #TODO
+LDCONFIG ?= ldconfig # TODO[1]
 LDCONFIGFLAGS ?=
 LEX ?= lex
-LEXFLAGS ?= $(LFLAGS)
+LFLAGS ?= # LFLAGS instead of LEXFLAGS
 #MAKE
 MAKEINFO ?= makeinfo
 MAKEINFOFLAGS ?=
-RANLIB ?= ranlib #TODO
+RANLIB ?= ranlib # TODO[1]
 RANLIBFLAGS ?=
 TEXI2DVI ?= texi2dvi
 TEXI2DVIFLAGS ?=
 YACC ?= yacc
-YACCFLAGS ?= $(YFLAGS)
+YFLAGS ?= # YFLAGS instead of YACCFLAGS
 
-CFLAGS ?=
-LFLAGS ?=
-YFLAGS ?=
+CPPFLAGS ?=
 
-LN_S ?= ln -s #TODO
+LN_S ?= ln -s # TODO[2]
 
 CHGRP ?= chgrp
+CHGRPFLAGS ?=
 CHMOD ?= chmod
+CHMODFLAGS ?=
 CHOWN ?= chown
+CHOWNFLAGS ?=
 MKNOD ?= mknod
+MKNODFLAGS ?=
+
+# [0]: There is no INSTALLFLAGS because it would be inconsistent with how the
+#      standards otherwise recommend using $(INSTALL); with INSTALL_PROGRAM and
+#      INSTALL_DATA; which are specified in a way precluding the use of
+#      INSTALLFLAGS.  To have the variable, but to ignore it in the common case
+#      would be confusing.
+#
+# [1]: The RANLIB and LDCONFIG variables need some extra smarts; §7.2.2 says:
+#
+#       > When you use ranlib or ldconfig, you should make sure nothing bad
+#       > happens if the system does not have the program in question. Arrange
+#       > to ignore an error from that command, and print a message before the
+#       > command to tell the user that failure of this command does not mean a
+#       > problem. (The Autoconf ‘AC_PROG_RANLIB’ macro can help with this.)
+#
+# [2]: The LN_S variable isn't standard, but we have it here as an (incomplete)
+#      stub to help support this bit of §7.2.2:
+#
+#       > If you use symbolic links, you should implement a fallback for
+#       > systems that don’t have symbolic links.
 
 # 7.2.3: Variables for Specifying Commands
 # ----------------------------------------
diff --git a/build-aux/Makefile.once.head/10-nested.mk b/build-aux/Makefile.once.head/10-nested.mk
new file mode 100644
index 0000000..4f181a9
--- /dev/null
+++ b/build-aux/Makefile.once.head/10-nested.mk
@@ -0,0 +1,45 @@
+# Copyright (C) 2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.nested.description = Easy nested .PHONY targets
+define mod.nested.doc
+# Inputs:
+#   - Global variable    : `nested.targets`
+#   - Directory variable : `nested.subdirs`
+# Outputs:
+#   - .PHONY Targets     : `$(addprefix $(outdir)/,$(nested.targets))`
+#   - Variable           : `at.subdirs`
+#
+# The Autothing `at.subdirs` slates a subdirectory's Makefile for inclusion,
+# but doesn't help with recursive targets like `all`, `install`, or `clean`,
+# which one would expect to descend into subdirectories.  Enter `nested`:
+# Define a global list of targets that are recursive/nested, and then in each
+# directory define a list of subdirectries that one would expect them to
+# recurse into.
+#
+# Directories added to `nested.subdirs` are automatically added to `at.subdirs`
+# during the each.tail phase.
+#
+# It may help to think of at.subdirs and nested.subdirs in terms of their
+# Automake conterparts:
+#
+#      | Autothing      | GNU Automake |
+#      +----------------+--------------+
+#      | at.subdirs     | DIST_SUBDIRS |
+#      | nested.subdirs | SUBDIRS      |
+endef
+mod.nested.doc := $(value mod.nested.doc)
+
+nested.targets ?=
diff --git a/build-aux/Makefile.once.head/10-std.mk b/build-aux/Makefile.once.head/10-std.mk
deleted file mode 100644
index 3e058ec..0000000
--- a/build-aux/Makefile.once.head/10-std.mk
+++ /dev/null
@@ -1,39 +0,0 @@
-# Copyright (C) 2015-2016  Luke Shumaker
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Affero General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Affero General Public License for more details.
-#
-# You should have received a copy of the GNU Affero General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-# Declare the default target
-all: build
-.PHONY: all noop
-
-# Standard creative PHONY targets
-at.phony += build install installdirs
-# Standard destructive PHONY targets
-at.phony += uninstall mostlyclean clean distclean maintainer-clean
-
-at.dirlocal += std.src_files
-at.dirlocal += std.gen_files
-at.dirlocal += std.cfg_files
-at.dirlocal += std.out_files
-at.dirlocal += std.sys_files
-at.dirlocal += std.clean_files
-at.dirlocal += std.slow_files
-
-# User configuration
-
-DESTDIR ?=
-
-RM      ?= rm -f
-RMDIR_P ?= rmdir -p
-TRUE    ?= true
diff --git a/build-aux/Makefile.once.head/10-texinfo.mk b/build-aux/Makefile.once.head/10-texinfo.mk
new file mode 100644
index 0000000..aac2c28
--- /dev/null
+++ b/build-aux/Makefile.once.head/10-texinfo.mk
@@ -0,0 +1,51 @@
+# Copyright (C) 2016-2017  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.texinfo.description = The GNU documentation system
+mod.texinfo.depends += files nested gnuconf
+define mod.texinfo.doc
+# User variables (in addition to gnuconf):
+#   - `TEXI2HTML ?= makeinfo --html`
+#   - `TEXI2PDF  ?= texi2pdf`
+#   - `TEXI2PS   ?= texi2dvi --ps`
+# Inputs:
+#   - Directory variable : `texinfo.docs ?=`
+# Outputs:
+#   - Global variable    : `files.groups += html dvi pdf ps`
+#   - Global variable    : `nested.targets += info`
+#   - Directory variable : `files.src.gen`
+#   - Directory variable : `files.out.{dvi,html,pdf,ps}`
+#   - Directory variable : `files.sys.{dvi,html,pdf,ps,all}`
+#   - .PHONY target      : `$(outdir)/info`
+#   - .PHONY target      : `$(outdir)/install` (see below)
+#   - Target             : `$(outdir)/%.info`
+#   - Target             : `$(outdir)/%.dvi`
+#   - target             : `$(outdir)/%.html`
+#   - target             : `$(outdir)/%.pdf`
+#   - Target             : `$(outdir)/%.ps`
+#
+# The module counts on the `$(outdir)/install` target being defined by
+# `files`, but not having a rule that executes once the dependencies
+# have been taken care of; it adds a "post-install" rule to add the
+# info files to the index.
+endef
+mod.texinfo.doc := $(value mod.texinfo.doc)
+
+TEXI2HTML ?= makeinfo --html
+TEXI2PDF  ?= texi2pdf
+TEXI2PS   ?= texi2dvi --ps
+
+files.groups += html dvi pdf ps
+nested.targets += info
diff --git a/build-aux/Makefile.once.head/10-write-atomic.mk b/build-aux/Makefile.once.head/10-write-atomic.mk
new file mode 100644
index 0000000..c4aa808
--- /dev/null
+++ b/build-aux/Makefile.once.head/10-write-atomic.mk
@@ -0,0 +1,23 @@
+mod.write-atomic.description = `write-atomic` auxiliary build script
+mod.write-atomic.files += $(topsrcdir)/build-aux/write-atomic
+define mod.write-atomic.doc
+# User variables:
+#   - `WRITE_ATOMIC ?= $(topsrcdir)/build-aux/write-atomic`
+# Inputs:
+#   (none)
+# Outputs:
+#   (none)
+#
+# The $(WRITE_ATOMIC) program reads a file from stdin, and writes it to
+# the file named in argv[1], but does so atomically.
+#
+# That is, the following lines are almost equivalient:
+#
+#     ... > $@
+#     ... | $(WRITE_ATOMIC) $@
+#
+# The are only different in that one is atomic, while the other is not.
+endef
+mod.write-atomic.doc := $(value mod.write-atomic.doc)
+
+WRITE_ATOMIC ?= $(topsrcdir)/build-aux/write-atomic
diff --git a/build-aux/Makefile.once.head/10-write-ifchanged.mk b/build-aux/Makefile.once.head/10-write-ifchanged.mk
new file mode 100644
index 0000000..649aab9
--- /dev/null
+++ b/build-aux/Makefile.once.head/10-write-ifchanged.mk
@@ -0,0 +1,23 @@
+mod.write-ifchanged.description = `write-ifchanged` auxiliary build script
+mod.write-ifchanged.files += $(topsrcdir)/build-aux/write-ifchanged
+define mod.write-ifchanged.doc
+# User variables:
+#   - `WRITE_IFCHANGED ?= $(topsrcdir)/build-aux/write-ifchanged`
+# Inputs:
+#   (none)
+# Outputs:
+#   (none)
+#
+# The $(WRITE_IFCHANGED) program reads a file from stdin, and writes it to the
+# file named in argv[1], but does so atomically, but more importantly, does so
+# in a way that does not bump the file's ctime if the new content is the same
+# as the old content.
+#
+# That is, the following lines are almost equivalient:
+#
+#     ... > $@
+#     ... | $(WRITE_ATOMIC) $@
+endef
+mod.write-ifchanged.doc := $(value mod.write-ifchanged.doc)
+
+WRITE_IFCHANGED ?= $(topsrcdir)/build-aux/write-ifchanged
diff --git a/build-aux/Makefile.once.head/zz-mod.mk b/build-aux/Makefile.once.head/zz-mod.mk
new file mode 100644
index 0000000..95d251d
--- /dev/null
+++ b/build-aux/Makefile.once.head/zz-mod.mk
@@ -0,0 +1,59 @@
+# Copyright (C) 2016  Luke Shumaker
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+mod.mod.description = Display information about Autothing modules
+mod.mod.depends += quote
+define mod.mod.doc
+# Inputs:
+#   - Files           : `$(topsrcdir)/build-aux/Makefile.*/??-*.mk`
+#   - Global variable : `mod.*.description`
+#   - Global variable : `mod.*.depends`
+#   - Global variable : `mod.*.files`
+#   - Global variable : `mod.*.doc`
+# Outputs:
+#   - Directory variable : `at.targets`
+#   - .PHONY Target      : `$(outdir)/at-variables-local`
+#   - .PHONY Target      : `$(outdir)/at-variables-global`
+#   - .PHONY Target      : `$(outdir)/at-variables`
+#   - .PHONY Target      : `$(outdir)/at-variables/%`
+#   - .PHONY Target      : `$(outdir)/at-values`
+#   - .PHONY Target      : `$(outdir)/at-values/%`
+#   - .PHONY Target      : `$(outdir)/at-modules`
+#   - .PHONY Target      : `$(outdir)/at-modules/%`
+#   - .PHONY Target      : `$(outdir)/at-noop`
+#
+# TODO: prose documentation
+endef
+mod.mod.doc := $(value mod.mod.doc)
+
+# The trickery that is _mod.empty/_mod.space is from §6.2 of the GNU Make
+# manual, "The Two Flavors of Variables".
+_mod.empty :=
+_mod.space := $(_mod.empty) #
+undefine _mod.empty
+# _mod.rest is equivalent to GMSL rest.
+_mod.rest = $(wordlist 2,$(words $1),$1)
+
+_mod.file2mod = $(foreach _mod.tmp,$(patsubst %.mk,%,$(notdir $1)),$(subst $(_mod.space),-,$(call _mod.rest,$(subst -, ,$(_mod.tmp)))))
+
+_mod.modules := $(sort $(call _mod.file2mod,$(wildcard $(topsrcdir)/build-aux/Makefile.*/??-*.mk)))
+undefine _mod.rest
+undefine _mod.file2mod
+
+$(eval $(foreach _mod.tmp,$(_mod.modules),\
+  mod.$(_mod.tmp).description ?=$(at.nl)\
+  mod.$(_mod.tmp).depends ?=$(at.nl)\
+  mod.$(_mod.tmp).files ?=$(at.nl)\
+  mod.$(_mod.tmp).doc ?=$(at.nl)))