Misc: add a release target for source tarballs

"make -f misc/GNUmakefile release" packages a tag into a
njs-<version>.tar.gz tarball with a checksum file.

The optional "release-check" target builds the extracted tarball.

Author: xeioex

.gitignore

@@ -2,3 +2,5 @@ node_modules/
 package-lock.json
 /build/
 /Makefile
+/njs-*.tar.gz
+/njs-*.tar.gz.sha256

misc/GNUmakefile

@@ -0,0 +1,36 @@
+
+VER =		$(shell grep 'define NJS_VERSION ' src/njs.h		\
+			| sed -e 's/^.*"\(.*\)".*/\1/')
+NJS =		njs-$(VER)
+TAG ?=		$(VER)
+TARBALL =	$(NJS).tar.gz
+
+
+release:
+	git archive --format=tar.gz --prefix=$(NJS)/ -o $(TARBALL) $(TAG)
+
+	sha256sum $(TARBALL) > $(TARBALL).sha256
+
+	@echo "excluded from $(TARBALL):"
+	@{ git ls-tree -r --name-only $(TAG);				\
+	   tar -t -z -f $(TARBALL) | grep -v "/$$"			\
+		| sed -e "s|^$(NJS)/||"; }				\
+	| sort | uniq -u
+
+
+# Builds the extracted tarball in a temporary directory, which is kept
+# around on failure.
+
+release-check:
+	@dir=`mktemp -d`;						\
+	echo "extracting $(TARBALL) into $$dir";			\
+	tar -x -z -f $(TARBALL) -C $$dir				\
+	&& cd $$dir/$(NJS)						\
+	&& ./configure							\
+	&& $(MAKE) njs							\
+	&& $(MAKE) unit_test						\
+	&& rm -rf $$dir							\
+	&& echo "$(TARBALL) builds"
+
+
+.PHONY: release release-check