From 09228836cf3d8a7c0c05609d9b2a878334620b6d Mon Sep 17 00:00:00 2001
From: midipix <writeonce@midipix.org>
Date: Sat, 8 Dec 2018 01:16:54 -0500
Subject: build system: support custom configuration via cfgdefs.sh (and
 usrdefs.mk).

---
 Makefile.in    | 13 +++++++++
 config.project |  3 ++
 configure      | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 99 insertions(+), 3 deletions(-)

diff --git a/Makefile.in b/Makefile.in
index 89d4904..e117fa6 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -100,6 +100,9 @@ DISABLE_FRONTEND	= @disable_frontend@
 DISABLE_SHARED          = @disable_shared@
 DISABLE_STATIC          = @disable_static@
 
+USE_CUSTOM_CFGDEFS      = @use_custom_cfgdefs@
+USE_CUSTOM_USRDEFS      = @use_custom_usrdefs@
+
 all:
 install:
 shared:
@@ -128,6 +131,13 @@ include $(PROJECT_DIR)/project/arch.mk
 include $(PROJECT_DIR)/project/extras.mk
 include $(PROJECT_DIR)/project/overrides.mk
 
+ifeq ($(USE_CUSTOM_CFGDEFS),yes)
+include ./cfgdefs.mk
+endif
+
+ifeq ($(USE_CUSTOM_USRDEFS),yes)
+include ./usrdefs.mk
+endif
 
 
 $(APP_SRCS:%.c=%.o): CFLAGS_STATIC = $(CFLAGS_APP)
@@ -434,6 +444,9 @@ clean:		clean-implib
 		@echo DISABLE_FRONTEND:'       '$(DISABLE_FRONTEND)
 		@echo DISABLE_SHARED:'         '$(DISABLE_SHARED)
 		@echo DISABLE_STATIC:'         '$(DISABLE_STATIC)
+		@echo
+		@echo USE_CUSTOM_CFGDEFS:'     '$(USE_CUSTOM_CFGDEFS)
+		@echo USE_CUSTOM_USRDEFS:'     '$(USE_CUSTOM_USRDEFS)
 
 .display-host:
 		@$(CC) $(CFLAGS) -dumpmachine
diff --git a/config.project b/config.project
index 049e5d0..fff6ce6 100644
--- a/config.project
+++ b/config.project
@@ -70,3 +70,6 @@ mb_all_shared=
 mb_disable_frontend=yes
 mb_disable_static=
 mb_disable_shared=
+
+mb_use_custom_cfgdefs=no
+mb_use_custom_usrdefs=no
diff --git a/configure b/configure
index e607fee..c75ad17 100755
--- a/configure
+++ b/configure
@@ -8,7 +8,28 @@
 usage()
 {
 	cat "$mb_project_dir"/config.usage
-	exit $?
+
+	if [ $mb_use_custom_cfgdefs = 'yes' ]; then
+		printf '\n\n%s%s\n' \
+			" ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" \
+			"^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"
+
+		printf '%s%s\n' \
+			"| Listed above are configure's common switches " \
+			"and environment variables.     |"
+
+		printf '%s%s\n' \
+			"| Found below are project-specific variables " \
+			"and other customization options. |"
+
+		printf '%s%s\n\n\n' \
+			" ___________________________________________" \
+			"__________________________________"
+
+		cat "$mb_project_dir"/project/config/cfgdefs.usage
+	fi
+
+	exit 0
 }
 
 error_msg()
@@ -33,6 +54,18 @@ init_vars()
 		. "$mb_config" || exit 2
 	fi
 
+	if [ $mb_use_custom_cfgdefs = 'yes' ]; then
+		mb_custom_cfgdefs_wrapper=$(mktemp)
+
+		if [ -z $mb_custom_cfgdefs_wrapper ]; then
+			error_msg "failed to create a temporary file."
+			exit 2
+		fi
+
+		printf '. $mb_project_dir/project/config/cfgdefs.sh \\\n' \
+			> $mb_custom_cfgdefs_wrapper
+	fi
+
 	# project
 	mb_nickname=$NICKNAME
 	mb_source_dir=$SOURCE_DIR
@@ -551,8 +584,19 @@ config_copy()
 			-e 's^@disable_frontend@^'"$mb_disable_frontend"'^g'		\
 			-e 's^@disable_static@^'"$mb_disable_static"'^g'		\
 			-e 's^@disable_shared@^'"$mb_disable_shared"'^g'		\
+											\
+			-e 's^@use_custom_cfgdefs@^'"$mb_use_custom_cfgdefs"'^g'	\
+			-e 's^@use_custom_usrdefs@^'"$mb_use_custom_usrdefs"'^g'	\
 		$mb_project_dir/Makefile.in > $mb_pwd/Makefile.tmp || exit 2
 
+	if [ $mb_use_custom_cfgdefs = 'yes' ]; then
+		touch cfgdefs.mk
+	fi
+
+	if [ $mb_use_custom_usrdefs = 'yes' ]; then
+		touch usrdefs.mk
+	fi
+
 	if [ -z "$mb_cchost" ]; then
 		if [ "$mb_host" = 'native' ]; then
 			mb_cchost=`make -s -f $mb_pwd/Makefile.tmp cchost`
@@ -560,7 +604,24 @@ config_copy()
 			mb_cchost=$mb_host
 		fi
 	fi
+}
+
+
+config_custom()
+{
+	if [ $mb_use_custom_cfgdefs = 'yes' ]; then
+		. $mb_custom_cfgdefs_wrapper
+		config_copy
+	fi
 
+	if [ $mb_use_custom_usrdefs = 'yes' ]; then
+		. $mb_project_dir/project/usrdefs.sh
+	fi
+}
+
+
+config_cfghost()
+{
 	if [ -z "$mb_cfghost" ]; then
 		mb_cfghost=$mb_cchost
 	fi
@@ -831,8 +892,25 @@ for arg ; do
 			;;
 
 		*)
-			error_msg ${arg#}: "unsupported config argument."
-			exit 2
+			if [ $mb_use_custom_cfgdefs = 'yes' ]; then
+				printf '\t' >> $mb_custom_cfgdefs_wrapper
+
+				mb_first='yes'
+
+				for mb_arg in $arg; do
+					if [ $mb_first = 'yes' ]; then
+						printf '%s' $mb_arg >> $mb_custom_cfgdefs_wrapper
+						mb_first='no'
+					else
+						printf '\\ %s' $mb_arg >> $mb_custom_cfgdefs_wrapper
+					fi
+				done
+
+				printf ' \\\n' >> $mb_custom_cfgdefs_wrapper
+			else
+				error_msg ${arg#}: "unsupported config argument."
+				exit 2
+			fi
 			;;
 	esac
 done
@@ -858,6 +936,8 @@ cross_defaults
 # five: config
 config_flags
 config_copy
+config_custom
+config_cfghost
 config_support
 config_host
 config_status
-- 
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