Re: [Buildroot] [PATCH 2/2] package/pkg-utils: teach per-package-rsync to copy or hardlink dest

[Herve Codina via buildroot <buildroot@buildroot.org>]

Hi Yann,

On Tue, 17 Oct 2023 23:01:20 +0200
"Yann E. MORIN" <yann.morin.1998@free.fr> wrote:

> commit 21d52e52d8de (package/pkg-utils.mk: break hardlinks in global
> {TARGET, HOST}_DIR on per-package build) was recently reverted, so we
> are back to a situation where it is possible for packages and post-build
> scripts to modify files in-place, and thus impact files in any arbitrary
> per-package directory, which may break things on rebuild for example.
> 
> 21d52e52d8de wsa too big a hammer, but we can still apply the reasoning

s/wsa/was/

> from it, to the aggregation of the final target and host directories.
> 
> This solves the case for post-build scripts at least. We leave the case
> of inter-package modification aside, as it is a bigger issue that will
> need more than jsut copying files around.

s/jsut/just/

> 
> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
> Cc: Herve Codina <herve.codina@bootlin.com>
> Cc: Peter Korsgaard <peter@korsgaard.com>
> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> ---
>  Makefile             |  4 ++--
>  package/pkg-utils.mk | 15 ++++++++++++---
>  2 files changed, 14 insertions(+), 5 deletions(-)
> 

[...]

> --- a/package/pkg-utils.mk
> +++ b/package/pkg-utils.mk
> @@ -214,10 +214,19 @@ ifeq ($(BR2_PER_PACKAGE_DIRECTORIES),y)
>  # $1: space-separated list of packages to rsync from
>  # $2: 'host' or 'target'
>  # $3: destination directory
> +# $4: literal "copy" or "hardlink" to copy or hardlink files from src to dest
>  define per-package-rsync
>  	mkdir -p $(3)
>  	$(foreach pkg,$(1),\
> -		rsync -a --link-dest=$(PER_PACKAGE_DIR)/$(pkg)/$(2)/ \
> +		rsync -a \
> +			--hard-links \

You preserve hard links (--hard-links) in all cases (copy and hardlink).
In case of copy, is it correct to preserve hard links ?

> +			$(if $(filter hardlink,$(4)), \
> +				--link-dest=$(PER_PACKAGE_DIR)/$(pkg)/$(2)/, \
> +				$(if $(filter copy,$(4)), \
> +					$(empty), \
> +					$(error per-package-rsync can only "copy" or "hardlink", not "$(4)") \
> +				) \
> +			) \
>  			$(PER_PACKAGE_DIR)/$(pkg)/$(2)/ \
>  			$(3)$(sep))
>  endef

[...]

Best regards,
Hervé
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