[Buildroot] [PATCH] core/sdk: generate the SDK tarball ourselves

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

All,

On 2018-06-09 23:06 +0200, Yann E. MORIN spake thusly:
> Currently, the wording in the manual instructs the user to generate
> tarball from "the contents of the +output/host+ directory".
> 
> This is pretty confusing, because taken literally, this would amount to
> runing a command like:
> 
>     tar cf my-sdk.tar -C output/host/ .
> 
> This creates a tarbomb [0], which is very bad practice, because when

I forgot to add the reference to the tarbomb:
    https://en.wikipedia.org/wiki/Tar_(computing)#Tarbomb

Regards,
Yann E. MORIN.

> extracted, it creates mutiple files in the current directory.
> 
> One one really want to do, is create a tarball of the host/ directory,
> with something like:
> 
>     tar cf my-sdk.tar -C output host/
> 
> However, this is not much better, because the top-most dirdctory would
> have a very common name, host/, which is pretty easy to get conflict
> with.
> 
> So, we fix that mess by creating the archive ourselves, giving it and
> the top-most directory a recogniseable name, based on the target tuple
> and the Buildroot version.
> 
> Since this is an output file, we located it in the images/ directory.
> 
> Update the manual accordignly.
> 
> Speaking of the manual.. It was referring to "output/host/", but that
> is only valid for in-tree builds. For out-of-tree builds, this is just
> "host/". To avoid confusion, use the name of the vairiable $(HOST_DIR),
> which, fortunately, happens to be valid in both cases.
> 
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> Cc: Wolfgang Grandegger <wg@grandegger.com>
> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> Cc: Arnout Vandecappelle <arnout@mind.be>
> Cc: Stefan Becker <chemobejk@gmail.com>
> ---
>  Makefile                                  |  7 ++++++-
>  docs/manual/using-buildroot-toolchain.txt | 26 +++++++++++++++++---------
>  2 files changed, 23 insertions(+), 10 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 4b998bdb65..3f460f8d92 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -574,13 +574,18 @@ prepare: $(BUILD_DIR)/buildroot-config/auto.conf
>  world: target-post-image
>  
>  .PHONY: sdk
> -sdk: world
> +sdk: world $(BR2_TAR_HOST_DEPENDENCY)
>  	@$(call MESSAGE,"Rendering the SDK relocatable")
>  	$(TOPDIR)/support/scripts/fix-rpath host
>  	$(TOPDIR)/support/scripts/fix-rpath staging
>  	$(INSTALL) -m 755 $(TOPDIR)/support/misc/relocate-sdk.sh $(HOST_DIR)/relocate-sdk.sh
>  	mkdir -p $(HOST_DIR)/share/buildroot
>  	echo $(HOST_DIR) > $(HOST_DIR)/share/buildroot/sdk-location
> +	$(Q)mkdir -p $(BINARIES_DIR)
> +	$(TAR) czf $(BINARIES_DIR)/buildroot-sdk.$(GNU_TARGET_NAME)-$(BR2_VERSION_FULL).tar.gz \
> +		-C $(HOST_DIR) \
> +		--transform='s#^\.#buildroot-sdk.$(GNU_TARGET_NAME)-$(BR2_VERSION_FULL)#' \
> +		.
>  
>  # Populating the staging with the base directories is handled by the skeleton package
>  $(STAGING_DIR):
> diff --git a/docs/manual/using-buildroot-toolchain.txt b/docs/manual/using-buildroot-toolchain.txt
> index 3246dc2411..d1490b4c38 100644
> --- a/docs/manual/using-buildroot-toolchain.txt
> +++ b/docs/manual/using-buildroot-toolchain.txt
> @@ -12,15 +12,23 @@ The toolchain generated by Buildroot is located by default in
>  +output/host/bin/+ to your PATH environment variable and then to
>  use +ARCH-linux-gcc+, +ARCH-linux-objdump+, +ARCH-linux-ld+, etc.
>  
> -It is possible to relocate the toolchain, this allows to distribute
> -the toolchain to other developers to build applications for your
> -target. To achieve this:
> +Alternatively, Buildroot can also export the toolchain and all the
> +development files of all selected packages, as an SDK, by running the
> +command +make sdk+. This generates a tarball of the content of the host
> +directory +$(HOST_DIR)+, named +buildroot-sdk.<TARGET-TUPLE>-<BR-VERSION>.tar.gz+
> +and located in the output directory +$(BINARIES_DIR)+.
>  
> -* run +make sdk+, which prepares the toolchain to be relocatable;
> -* tarball the contents of the +output/host+ directory;
> -* distribute the resulting tarball.
> +This tarball can then be distributed to application developpers, when
> +they want to develop their applications that are not (yet) packaged as
> +a Buildroot package.
>  
> -Once the toolchain is installed to the new location, the user must run
> -the +relocate-sdk.sh+ script to make sure all paths are updated with
> -the new location.
> +Upon extracting the SDK tarball, the user must run the script
> ++relocate-sdk.sh+, to make sure all paths are updated with the new
> +location.
>  
> +.Note
> +This SDK can not be re-used as an external toolchain, because it
> +contains pre-built libraries that could be conflicting with the ones
> +packaged in Buildroot (e.g. when an old SDK would be re-used with a
> +newer Buildroot version), unless it was built from a configuration
> +with no package enabled.
> -- 
> 2.14.1
> 

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