[Buildroot] [PATCHv3 1/5] core: introduce the BR2_EXTERNAL variable

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

Thomas, All,

On 2013-11-27 23:31 +0100, Thomas Petazzoni spake thusly:
> This commit introduces the BR2_EXTERNAL environment variable, which
> will allow to keep Buildroot customization (board-specific
> configuration files or root filesystem overlays, package Config.in and
> makefiles, as well as defconfigs) outside of the Buildroot tree.
> 
> This commit only introduces the variable itself, and ensures that it
> is available within Config.in options, so that string options used to
> specify paths to directories or files can use $BR2_EXTERNAL as a
> reference. For example, one can use
> $BR2_EXTERNAL/board/<someboard>/kernel.config as the
> BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE value.
[--SNIP--]

With only this commit applied, and a clean tree, I get:

    $ make menuconfig
    Makefile:136: *** "The specified BR2_EXTERNAL '' location doesn't
    exist".  Stop.

> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
[--SNIP--]
> diff --git a/Makefile b/Makefile
> index b5368a3..a46418e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -99,6 +99,45 @@ export CDPATH:=
[--SNIP--]
> +BR2_EXTERNAL_FILE = $(BASE_DIR)/.br-external
> +
> +ifeq ($(origin BR2_EXTERNAL),command line)
> +ifeq ($(BR2_EXTERNAL),) # Case 1
> +override BR2_EXTERNAL := $(TOPDIR)/support/dummy-external/
> +$(shell rm -f $(BR2_EXTERNAL_FILE))
> +else # Case 2
> +ifeq ($(wildcard $(BR2_EXTERNAL)),)
> +$(error "The specified BR2_EXTERNAL '$(BR2_EXTERNAL)' location doesn't exist")
> +endif
> +override BR2_EXTERNAL := $(realpath $(BR2_EXTERNAL))
> +BR2_EXTERNAL_USED = y
> +$(shell echo $(BR2_EXTERNAL) > $(BR2_EXTERNAL_FILE))
> +endif
> +else # Case 3
> +override BR2_EXTERNAL := $(shell test -f $(BR2_EXTERNAL_FILE) && cat $(BR2_EXTERNAL_FILE))
> +ifeq ($(wildcard $(BR2_EXTERNAL)),)
> +$(error "The specified BR2_EXTERNAL '$(BR2_EXTERNAL)' location doesn't exist")

The error occurs here.

That's becasue you test if BR2_EXTERNAL is comming from the command
line, but that last case should also test if BR2_EXTERNAL_FILE exists
before scanning it.

Regards,
Yann E. MORIN.

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