backports: minimize diffs with base debian files

[mirror_frr.git] / debian / backports / rules

.PHONY: backports $(KNOWN_BACKPORTS)

# error out if these files are missing
required_files = $(foreach backport,$(KNOWN_BACKPORTS), \
	$(addprefix debian/backports/$(backport)/, \
		debian/source/format \
		versionext \
		exclude))
$(if $(filter-out $(wildcard $(required_files)),$(required_files)), \
	$(error missing required backports files: \
		$(filter-out $(wildcard $(required_files)),$(required_files)). \
		see debian/backports/README) \
)

TARBALLDIR ?= $(shell dh_testdir debian/changelog && realpath .)

define backports-targets
# if this file is empty, no automatic changelog entry is created
VERSIONEXT_$(1) ?= $(strip \
	$(shell cat $(wildcard debian/backports/$(1)/versionext)))
DEBIAN_VERSION_$(1) = $(DEBIAN_VERSION)$$(VERSIONEXT_$(1))
BACKPORTDIR_$(1) = $(realpath debian/backports/$(1))

# as of right now, must be '3.0 (quilt)'
SOURCEFORMAT_$(1) ?= $(strip \
	$(shell cat debian/backports/$(1)/debian/source/format))

# files checked for the dirhash (see below)
FINDCMD_$(1) = find -L debian/backports/$(1)/debian \
	-type f \
	! -path debian/backports/$(1)/debian/changelog

# files *not* pulled from the root debian directory into the backport tarball:
# debian/changelog (copied and edited for backport version entry)
# debian/backports itself (relevant contents are copied out separately)
# anything provided in the current backports debian dir
# anything specified in the 'exclude' file in the current backports debian dir
EXCLUDEROOT_$(1) = debian/changelog debian/backports \
	$$(subst debian/backports/$(1)/,,$$(shell $$(FINDCMD_$(1)))) \
	$$(shell cat debian/backports/$(1)/exclude)

EXCLUDEROOT_TAR_$(1) = $$(foreach file,$$(EXCLUDEROOT_$(1)),--exclude $$(file))
EXCLUDEROOT_FIND_$(1) = $$(foreach file,$$(EXCLUDEROOT_$(1)),-o -path $$(file))

# find command resulting in all files that *will* be pulled into the backport
# tarball.
FINDCMDROOT_$(1) = find -L debian/ \
	'(' -false $$(EXCLUDEROOT_FIND_$(1)) ')' -prune -o \
	-type f -a '!' '(' -false $$(EXCLUDEROOT_FIND_$(1)) ')'

# usually using `find' output for dependencies has the downfall of not tracking
# file removal. Work around that by introducing a dependency on a file whose
# name contains the hash of `find' output, so that the name will change when a
# file is deleted.
DIRHASH_$(1) = \
	$$(shell $$(FINDCMD_$(1)) | sha1sum | sed -r 's/^(......).*/\1/')
DIRHASHROOT_$(1) = \
	$$(shell $$(FINDCMDROOT_$(1)) | sha1sum | sed -r 's/^(......).*/\1/')

CONTROL_$(1) = $$(strip \
	$$(if $$(wildcard $$(BACKPORTDIR_$(1))/debian/control), \
		$$(BACKPORTDIR_$(1))/debian/control, \
		$(realpath debian/control) \
	))

# TARGETS:

$(1): $(TARBALLDIR)/$(SRCPKG)_$$(DEBIAN_VERSION_$(1)).dsc ;

# we use 3.0 (custom) to build a source package directly from tarballs,
# bypassing the usual checks (which wouldn't like our combination-of-
# directories approach)
$(TARBALLDIR)/$(SRCPKG)_$$(DEBIAN_VERSION_$(1)).dsc:
	# -b directory does nothing but determine will the .dsc will end up
	# for the custom source format. Put it in the current directory by
	# specifying one of its subdirs.
	dpkg-source -l$$(BACKPORTDIR_$(1))/debian/changelog \
		-c$$(CONTROL_$(1)) \
		--format='3.0 (custom)' \
		--target-format='$$(SOURCEFORMAT_$(1))' \
		-b debian $$^

ifeq ($$(SOURCEFORMAT_$(1)),3.0 (quilt))
# this target depends on the orig.tar.gz file, for which there is no target in
# this makefile. It is assumed to either already exist or be built by a target
# provided elsewhere in debian/rules (e.g. via pristine-tar)
$$(if $$(findstring $(ORIG_VERSION),$$(DEBIAN_VERSION_$(1))), \
	$$(info downstream version matches upstream version (good)), \
	$$(error quilt format expects downstream version \
		($$(DEBIAN_VERSION_$(1))) to contain upstream version \
		($(ORIG_VERSION)). Make a new debian/changelog entry \
		to reflect the new upstream release) \
)

$(TARBALLDIR)/$(SRCPKG)_$$(DEBIAN_VERSION_$(1)).dsc: \
		$(TARBALLDIR)/$(SRCPKG)_$(ORIG_VERSION).orig.tar.gz \
		$(TARBALLDIR)/$(SRCPKG)_$$(DEBIAN_VERSION_$(1)).debian.tar.xz
else
$$(error unsupported source format for $(1) backport: $$(SOURCEFORMAT_$(1)))
endif #SOURCEFORMAT_$(1)

# for 3.0 (quilt)
$(TARBALLDIR)/$(SRCPKG)_$$(DEBIAN_VERSION_$(1)).debian.tar.xz: \
		$$(BACKPORTDIR_$(1))/debian/changelog \
		$$(shell $$(FINDCMD_$(1))) \
		$$(BACKPORTDIR_$(1))/$$(DIRHASH_$(1)).backport.dirhash \
		$$(shell $$(FINDCMDROOT_$(1))) \
		$$(BACKPORTDIR_$(1))/$$(DIRHASHROOT_$(1)).root.dirhash \
		$$(BACKPORTDIR_$(1))/exclude
	rm -f $$(subst .tar.xz,.tar,$$@) $$@
	tar -chf $$(subst .tar.xz,.tar,$$@) \
		--exclude-vcs $$(EXCLUDEROOT_TAR_$(1)) debian/
	cd debian/backports/$(1) && tar -uhf $$(subst .tar.xz,.tar,$$@) \
		--exclude-vcs debian/
	xz $$(subst .tar.xz,.tar,$$@)

$$(BACKPORTDIR_$(1))/debian/changelog: \
		debian/changelog \
		debian/backports/$(1)/versionext
	rm -f debian/backports/$(1)/debian/changelog
	cp $$< $$@
	$(if $$(VERSIONEXT_$(1)), \
		dch -c $$@ -v '$$(DEBIAN_VERSION_$(1))' -b \
			'backport to $(1) systems', \
	)

$$(BACKPORTDIR_$(1))/$$(DIRHASH_$(1)).backport.dirhash:
	rm -f debian/backports/$(1)/*.backport.dirhash
	touch $$@

$$(BACKPORTDIR_$(1))/$$(DIRHASHROOT_$(1)).root.dirhash:
	rm -f debian/backports/$(1)/*.root.dirhash
	touch $$@

endef # backports-targets
$(foreach backport,$(KNOWN_BACKPORTS),$(eval \
	$(call backports-targets,$(backport))))

backports: $(KNOWN_BACKPORTS)