[Buildroot] [PATCH] package/environment-setup: new package

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

Angelo, All,

On 2020-04-18 12:31 +0200, Angelo Compagnucci spake thusly:
> Install an helper script to setup a build environment
> based on buildroot. It's useful when you export an sdk
> and want to use buildroot to build an external project.
> 
> Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
> ---
>  docs/manual/using-buildroot-toolchain.txt     |  7 +++++
>  package/Config.in                             |  1 +
>  package/environment-setup/Config.in           |  6 ++++
>  .../environment-setup/environment-setup.mk    | 28 +++++++++++++++++++
>  4 files changed, 42 insertions(+)
>  create mode 100644 package/environment-setup/Config.in
>  create mode 100644 package/environment-setup/environment-setup.mk
> 
> diff --git a/docs/manual/using-buildroot-toolchain.txt b/docs/manual/using-buildroot-toolchain.txt
> index 0c0c35fced..15096cfec8 100644
> --- a/docs/manual/using-buildroot-toolchain.txt
> +++ b/docs/manual/using-buildroot-toolchain.txt
> @@ -27,6 +27,13 @@ Upon extracting the SDK tarball, the user must run the script
>  +relocate-sdk.sh+ (located at the top directory of the SDK), to make
>  sure all paths are updated with the new location.
>  
> +For your convenience, by selecting the package BR2_PACKAGE_ENVIRONMENT_SETUP,
> +you can have a +setup-environment.sh+ script installed in +output/host/+.
> +This script can be sourced with +. environment-setup.sh+ to launch
> +the buildroot shell. Inside this shell, you will find an environment already
> +set up with the correct PATH, the complete list of +target configure+
> +variables and some useful commands like the +configure+ alias.

I don't think this should warrant a blurb in the manual. Otherwise, you
would have to add the same for the meson cross-compilation file that we
provide. And the ones for cmake as well...

Also. I don't like it being a package. There is no reason for that.
Instead, install it like we do the similar other cross-compilaiton
helpers, with the package that actually provides the tools:

  - the mexon's cross-compilation file is installed by host-meson

  - the cmake's toolchainfile.cmake and Buildroot.cmake files are
    installed by the cmake infra (yeah, that's not so nice...)

So, since this script is geared towards autotools, I guess host-autoconf
should bear the burden of installing that file.

> diff --git a/package/environment-setup/Config.in b/package/environment-setup/Config.in
> new file mode 100644
> index 0000000000..f0fcc7d0f8
> --- /dev/null
> +++ b/package/environment-setup/Config.in
> @@ -0,0 +1,6 @@
> +config BR2_PACKAGE_ENVIRONMENT_SETUP
> +	bool "Environment setup"
> +	help
> +	  Install an helper script to setup a build environment
> +	  based on buildroot. It's useful when you export an sdk
> +	  and want to use buildroot to build an external project
> diff --git a/package/environment-setup/environment-setup.mk b/package/environment-setup/environment-setup.mk
> new file mode 100644
> index 0000000000..840ee2a1a0
> --- /dev/null
> +++ b/package/environment-setup/environment-setup.mk
> @@ -0,0 +1,28 @@
> +################################################################################
> +#
> +# environment-setup
> +#
> +################################################################################
> +
> +ENVIRONMENT_SETUP_FILE = $(HOST_DIR)/environment-setup.sh

Don't install that at the root of the host dir, that's ugly.

> +ENVIRONMENT_SETUP_SED_EXP = --expression='s+$(HOST_DIR)+\$$SDK_PATH+g'
> +
> +define ENVIRONMENT_SETUP_INSTALL_TARGET_CMDS
> +	cp package/environment-setup/environment-setup.sh $(ENVIRONMENT_SETUP_FILE)

package/environment-setup/environment-setup.sh is missing in your patch.

Also, I don't think it should spawn a shell. Instead, it should be a
file that has to be sourced:

    . /path/to/sdk-dir/usr/share/buildroot/autoconf-env

> +	for var in $(TARGET_CONFIGURE_OPTS); do \

No-no: there are variables which values have spaces in them; that's not
going to work very well for those...

> +		echo export \"$$var\" | sed $(ENVIRONMENT_SETUP_SED_EXP) >> $(ENVIRONMENT_SETUP_FILE); \

Why don't you just do (export can export multiple variables_:

    printf 'export %s\n' '$(TARGET_CONFIGURE_OPTS)' >>$(ENVIRONMENT_SETUP_FILE)

(use printf, not echo).

> +	done
> +	echo export \"CROSS_COMPILE=$(TARGET_CROSS)\" | sed $(ENVIRONMENT_SETUP_SED_EXP) >> $(ENVIRONMENT_SETUP_FILE)

Is CROSS_COMPILE really a variable used by autotools?

Yeah, kernel... But this file should be only autotools, like the ones
we have for meson and cmake.

> +	echo export \"CONFIGURE_FLAGS=--target=$(GNU_TARGET_NAME) \
> +		--host=$(GNU_TARGET_NAME) \
> +		--build=$(GNU_HOST_NAME) \
> +		--prefix=/usr \
> +		--exec-prefix=/usr \
> +		--sysconfdir=/etc \
> +		--localstatedir=/var \
> +		--program-prefix=\" >> $(ENVIRONMENT_SETUP_FILE)
> +	echo "PS1=\"\[\e[32m\]buildroot-$(BR2_VERSION)\[\e[m\]:\[\e[34m\]\w\[\e[m\]\$$ \"" >> $(ENVIRONMENT_SETUP_FILE)

Do not ever play with the PS1 of users: they all have their prompt very
well crafted over the years! ;-] And this is absolutely not usefull for
the purpose of that script.

Regards,
Yann E. MORIN.

> +	echo alias "configure=\"./configure \$${CONFIGURE_FLAGS}\"" >> $(ENVIRONMENT_SETUP_FILE)
> +endef
> +
> +$(eval $(generic-package))
> -- 
> 2.17.1
> 
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