1 files changed, 116 insertions, 0 deletions
diff --git a/build-aux/Makefile.head.mk b/build-aux/Makefile.head.mk
new file mode 100644
index 0000000000..6ac3d49f9f
--- /dev/null
+++ b/build-aux/Makefile.head.mk
@@ -0,0 +1,116 @@
+# Copyright (C) 2015-2017  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/>.
+
+at.Makefile ?= Makefile
+_at.MAKEFILE_LIST ?=
+_at.MAKEFILE_LIST := $(strip $(_at.MAKEFILE_LIST) $(lastword $(filter %/$(at.Makefile),$(abspath $(MAKEFILE_LIST)))))
+
+# This bit only gets evaluated once, at the very beginning
+ifeq ($(origin _at.NO_ONCE),undefined)
+
+# Internal functions ###################################################
+
+# These 4 functions are all $(call _at.func,parent,child)
+_at.is_strict_subdir  = $(filter $(abspath $1)/%,$(abspath $2))
+_at.is_subdir         = $(filter $(abspath $1)/%,$(abspath $2)/.)
+_at.relbase = $(strip                                                   \
+  $(if $(call _at.is_subdir,$1,$2),                                     \
+       $(patsubst %/.,%,$(patsubst $(abspath $1)/%,%,$(abspath $2)/.)), \
+       $(abspath $2)))
+_at.relto = $(strip                                                     \
+  $(if $(call _at.is_subdir,$1,$2),                                     \
+       $(patsubst %/.,%,$(patsubst $(abspath $1)/%,%,$(abspath $2)/.)), \
+       ../$(call _at.relto,$(dir $(abspath $1)),$2)))
+
+# These 3 functions only take one operand; we define public multi-operand
+# versions below.
+_at.path = $(strip $(or                                                                                         \
+  $(if $(call _at.is_subdir,      .     ,$1),                              $(call _at.relto,      .     ,$1) ), \
+  $(if $(call _at.is_subdir,$(topoutdir),$1),$(patsubst %/.,%,$(topoutdir)/$(call _at.relto,$(topoutdir),$1))), \
+  $(if $(call _at.is_subdir,$(topsrcdir),$1),$(patsubst %/.,%,$(topsrcdir)/$(call _at.relto,$(topsrcdir),$1))), \
+  $(abspath $1)))
+_at.out2src = $(call _at.path,$(strip                  \
+  $(if $(call _at.is_subdir,$(topoutdir),$1),          \
+       $(topsrcdir)/$(call _at.relto,$(topoutdir),$1), \
+       $1)))
+_at.addprefix = $(call _at.path,$(if $(filter-out /%,$2),$1/$2,$2))
+
+_at.rest = $(wordlist 2,$(words $1),$1)
+_at.reverse = $(if $1,$(call _at.reverse,$(_at.rest))) $(firstword $1)
+
+_at.target_variable           = $(_at.target_variable.$(flavor $2))
+_at.target_variable.recursive = $1: private $2  = $(subst $(at.nl),$$(at.nl),$(value $2))
+_at.target_variable.simple    = $1: private $2 := $$($2)
+
+_at.quote-pattern = $(subst %,\%,$(subst \,\\,$1))
+
+# Sanity checking ######################################################
+ifeq ($(filter undefine,$(.FEATURES)),)
+$(error Autothing: We need a version of Make that supports 'undefine')
+endif
+ifeq ($(topsrcdir),)
+$(error Autothing: topsrcdir must be set (and non-empty) before including Makefile.head.mk)
+endif
+ifeq ($(topoutdir),)
+$(error Autothing: topoutdir must be set (and non-empty) before including Makefile.head.mk)
+endif
+ifneq ($(call _at.is_strict_subdir,$(topoutdir),$(topsrcdir)),)
+$(error Autothing: topsrcdir=$(topsrcdir) must not be a subdirectory of topoutdir=$(topoutdir))
+endif
+
+# External provisions ##################################################
+
+# These 4 functions are all $(call _at.func,parent,child)
+at.is_subdir = $(_at.is_subdir)
+at.is_strict_subdir = $(_at.is_strict_subdir)
+#at.relbase = $(if $2,$(shell realpath -sm --relative-base=$1 -- $2))
+at.relbase = $(foreach _at.tmp,$2,$(call _at.relbase,$1,$(_at.tmp)))
+#at.relto   = $(if $2,$(shell realpath -sm --relative-to=$1   -- $2))
+at.relto   = $(foreach _at.tmp,$2,$(call _at.relto,$1,$(_at.tmp)))
+
+at.path    = $(foreach _at.tmp,$1,$(call _at.path,$(_at.tmp)))
+at.out2src = $(foreach _at.tmp,$1,$(call _at.out2src,$(_at.tmp)))
+at.addprefix = $(foreach _at.tmp,$2,$(call _at.addprefix,$1,$(_at.tmp)))
+
+define at.nl
+
+
+endef
+
+# Include modules ######################################################
+include $(sort $(wildcard $(topsrcdir)/build-aux/Makefile.once.head/*.mk))
+_at.tmp_targets =
+_at.tmp_subdirs =
+_at.VARIABLES =
+_at.VARIABLES := $(.VARIABLES)
+
+endif # _at.NO_ONCE
+
+# This bit gets evaluated for each Makefile
+
+outdir := $(call _at.path,$(dir $(lastword $(_at.MAKEFILE_LIST))))
+ifeq ($(call _at.is_subdir,$(topoutdir),$(outdir)),)
+$(error Autothing: not a subdirectory of topoutdir=$(topoutdir): $(outdir))
+endif
+
+srcdir := $(call _at.out2src,$(outdir))
+ifeq ($(call _at.is_subdir,$(topsrcdir),$(srcdir)),)
+$(error Autothing: not a subdirectory of topsrcdir=$(topsrcdir): $(srcdir))
+endif
+
+at.subdirs =
+at.targets =
+
+include $(sort $(wildcard $(topsrcdir)/build-aux/Makefile.each.head/*.mk))