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

[Yann E. MORIN <yann.morin.1998@free.fr>]

Carlos, All,

On 2018-05-03 09:19 -0300, Carlos Santos spake thusly:
> 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).

In that case, I suggest your use a post-build script instead.

In facct, I think that any modifications that change the layout of the
filesystem should be done as a post-build script rather than an overlay.

So, I am pretty much reluctant to see this patch go in.

Regards,
Yann E. MORIN.

> 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.
> 
> Signed-off-by: Carlos Santos <casantos@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 "$$not_merged_dirs" && { \
> +			echo "ERROR: The custom skeleton in $(d) is not" \
> +				"using a merged /usr for the following directories:" \
> +				$$not_merged_dirs; \
> +			exit 1; \
> +		} || true)
> +
> +endif # merged /usr
> +
>  	@$(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))
>  
> -- 
> 2.14.3
> 
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