[Buildroot] [PATCH v2 3/4] Makefile: check rootfs overlays with BR2_ROOTFS_MERGED_USR enabled

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Mon,  7 May 2018 09:46:39 -0300, Carlos Santos wrote:
> 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
> 
> Fix the problem by adding a step in target-finalize that checks each
> overlay, using the same criteria used in skeleton-custom.mk.
> 
> Add a paragraph to the documentation clarifying that rootfs overlays
> don't need to contain /bin, /lib or /sbin and must not contain them when
> BR2_ROOTFS_MERGED_USR is enabled.
> 
> Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
> ---
> Changes v1->v2:
> 
> - Rebase series to HEAD of master branch
> - Rework commit message and documentation, as suggested by Thomas
>   Petazzoni
> ---
>  Makefile                         | 20 +++++++++++++++++---
>  docs/manual/customize-rootfs.txt |  8 ++++++++
>  2 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index c024c65f78..dc51269143 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -746,11 +746,25 @@ 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)"); \
> +		not_merged_dirs="$$(support/scripts/check-merged-usr.sh $(d))"; \
> +		test -n "$$not_merged_dirs" && { \
> +			echo "ERROR: The overlay in $(d) is not" \
> +				"using a merged /usr for the following directories:" \
> +				$$not_merged_dirs; \
> +			exit 1; \
> +		} || true$(sep))
> +
> +endif # merged /usr
> +
>  	@$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \
>  		$(call MESSAGE,"Copying overlay $(d)"); \
> -		rsync -a --ignore-times --keep-dirlinks $(RSYNC_VCS_EXCLUSIONS) \
> -			--chmod=u=rwX,go=rX --exclude .empty --exclude '*~' \
> -			$(d)/ $(TARGET_DIR)$(sep))
> +		$(call SYSTEM_RSYNC,$(d),$(TARGET_DIR))$(sep))

This specific chunk is not directly related to checking that overlays
comply with the merged /usr rule, so shouldn't this be in a separate
commit ?

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com