[Buildroot] [PATCH] Makefile: check rootfs overlays with BR2_ROOTFS_MERGED_USR enabled

[Peter Korsgaard]

>>>>> "Carlos" == Carlos Santos <casantos at datacom.ind.br> writes:

 > Since commit 0db34529f48 we use rsync with the --keep-dirlinks option to
 > prevent overlays from accidentally overwriding /{usr,bin,sbin,lib} links
 > when BR2_ROOTFS_MERGED_USR option is enabled. Unfortunately this also
 > prevents replacing a symlink by a directory on purpose (e.g. /var/log,
 > to persist system logs).

 > Steps to reproduce:

 > - enable BR2_ROOTFS_MERGED_USR and BR2_PACKAGE_SKELETON_INIT_SYSV
 > - mkdir some_path/rootfs-overlay/var/log
 > - enable BR2_ROOTFS_OVERLAY="some_path/rootfs-overlay"
 > - run 'make'
 > - 'target/var/log' is still a symlink to '../tmp', not a directory

Funny enough I ran into the exact same issue (also with /var/log)
yesterday, and I agree that it isn't really obvious why it doesn't work
whereas overwriting symlinks to files does work (E.G. our
/etc/resolv.conf -> /tmp/resolv.conf can be overridden by an overlay
containing /etc/resolv.conf).


 > Fix the problem by adding a step in target-finalize that checks each
 > overlay, using the same criteria used in skeleton-custom.mk.

It would be good if we could refactor this so we wouldn't have two
copies of the same code, either by moving it to a variable or simply
checking TARGET_DIR after overlays and post-build scripts?


 > Signed-off-by: Carlos Santos <casantos at datacom.ind.br>
 > ---
 >  Makefile | 33 ++++++++++++++++++++++++++++++++-
 >  1 file changed, 32 insertions(+), 1 deletion(-)

 > diff --git a/Makefile b/Makefile
 > index 957ba6634a..1b306f8556 100644
 > --- a/Makefile
 > +++ b/Makefile
 > @@ -751,9 +751,40 @@ endif
 >  	@$(call MESSAGE,"Sanitizing RPATH in target tree")
 >  	$(TOPDIR)/support/scripts/fix-rpath target
 
 > +# For a merged /usr, ensure that /lib, /bin and /sbin and their /usr
 > +# counterparts are appropriately setup as symlinks ones to the others.
 > +ifeq ($(BR2_ROOTFS_MERGED_USR),y)
 > +
 > +	@$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \
 > +		$(call MESSAGE,"Sanity check in overlay $(d)"); \
 > +		lib_inode=$$(stat -c '%i' $(d)/lib/. 2>/dev/null || true); \
 > +		bin_inode=$$(stat -c '%i' $(d)/bin/. 2>/dev/null || true); \
 > +		sbin_inode=$$(stat -c '%i' $(d)/sbin/. 2>/dev/null || true); \
 > +		usr_lib_inode=$$(stat -c '%i' $(d)/usr/lib/. 2>/dev/null || true); \
 > +		usr_bin_inode=$$(stat -c '%i' $(d)/usr/bin/. 2>/dev/null || true); \
 > +		usr_sbin_inode=$$(stat -c '%i' $(d)/usr/sbin/. 2>/dev/null || true); \
 > +		not_merged_dirs=""; \
 > +		test -z "$$lib_inode" || \
 > +			test "$$lib_inode" = "$$usr_lib_inode" || \
 > +				not_merged_dirs="$$not_merged_dirs /lib"; \
 > +		test -z "$$bin_inode" || \
 > +			test "$$bin_inode" = "$$usr_bin_inode" || \
 > +				not_merged_dirs="$$not_merged_dirs /bin"; \
 > +		test -z "$$sbin_inode" || \
 > +			test "$$sbin_inode" = "$$usr_sbin_inode" || \
 > +				not_merged_dirs="$$not_merged_dirs /sbin"; \
 > +		test -n "$$not_merged_dirs" && { \
 > +			echo "ERROR: The custom skeleton in $(d) is not" \

s/custom skeleton/overlay/

>  	@$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \
 >  		$(call MESSAGE,"Copying overlay $(d)"); \
 > -		rsync -a --ignore-times --keep-dirlinks $(RSYNC_VCS_EXCLUSIONS) \
 > +		rsync -a --ignore-times $(RSYNC_VCS_EXCLUSIONS) \
 >  			--chmod=u=rwX,go=rX --exclude .empty --exclude '*~' \
 >  			$(d)/ $(TARGET_DIR)$(sep))

This is afaik now identical to the SYSTEM_RSYNC logic we have in
system/system.mk, so it would be nicer to use that variable here.

-- 
Bye, Peter Korsgaard