[Buildroot] [PATCHv2] package/linux-firmware: fix special cases of symlinks

[Antoine Tenart]

Hi Yann,

On Wed, Mar 04, 2020 at 05:55:32PM +0100, Yann E. MORIN wrote:
> From: Antoine Tenart <antoine.tenart at bootlin.com>
> 
> Some symlinks were not created correctly when installing the
> Linux-firmware package. This patch fixes the support for all symlinks of
> the form:
> 
>   a/foo -> bar
>   a/foo -> b/bar
>   a/foo -> ../b/bar
> 
> With this patch all forms of symlinks described in the WHENCE file
> should be supported, whether they are in nested directories, or in
> non-existing ones.
> 
> As some symlinks could be in directories that do not exist, we must
> maje sure to canonicalize the path before testing the linked-to file.
> 
> We compared the symlinks installed pre-20200122 to what we have now, and
> it seems we're handling all of them with this patch.
> 
> Fixes: 55df4059d24b ("package/linux-firmware: fix symlink support")
> Signed-off-by: Antoine Tenart <antoine.tenart at bootlin.com>
> [yann.morin.1998 at free.fr:
>   - use readlink in canonicalize-missing mode, to avoid
>     creating-then-removing directories
> ]
> Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>

I tested it and it looks good.

Thanks,
Antoine

> ---
>  package/linux-firmware/linux-firmware.mk | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/package/linux-firmware/linux-firmware.mk b/package/linux-firmware/linux-firmware.mk
> index 009202d604..6d3cec1a48 100644
> --- a/package/linux-firmware/linux-firmware.mk
> +++ b/package/linux-firmware/linux-firmware.mk
> @@ -609,12 +609,18 @@ endif
>  # automatically by its copy-firmware.sh script during the installation, which
>  # parses the WHENCE file where symlinks are described. We follow the same logic
>  # here, adding symlink only for firmwares installed in the target directory.
> -# The grep/sed parsing is taken from the script mentioned before.
> +#
> +# For testing the presence of firmwares in the target directory we first make
> +# sure we canonicalize the pointed-to file, to cover the symlinks of the form
> +# a/foo -> ../b/foo  where a/ (the directory where to put the symlink) does
> +# not yet exist.
>  define LINUX_FIRMWARE_CREATE_SYMLINKS
> +	cd $(TARGET_DIR)/lib/firmware/ ; \
>  	sed -r -e '/^Link: (.+) -> (.+)$$/!d; s//\1 \2/' $(@D)/WHENCE | \
>  	while read f d; do \
> -		if test -f $(TARGET_DIR)/lib/firmware/$$d; then \
> -			ln -sf $$d $(TARGET_DIR)/lib/firmware/$$f || exit 1; \
> +		if test -f $$(readlink -m $$(dirname $$f)/$$d); then \
> +			mkdir -p $$(dirname $$f) || exit 1; \
> +			ln -sf $$d $$f || exit 1; \
>  		fi ; \
>  	done
>  endef
> -- 
> 2.20.1
> 

-- 
Antoine Ténart, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com