[7/9,v4] core: add support for multiple br2-external trees

Currently, we only support at most one br2-external tree. Being able
to use more than one br2-external tree can be very useful.

A use-case would be for having a br2-external to contain the basic
packages, basic board defconfigs and board files, provided by one team
responsible for the "board-bringup", while other teams consume that
br2-external as a base, and complements it each with their own set of
packages, defconfigs and extra board files.

Another use-case would be for third-parties to provide their own
Buildroot packaging in a br2-external tree, along-side the archives for
their stuff.

Finally, another use-case is to be able to add FLOSS packages in a
br2-external tree, and proprietary packages in another. This allows
to not touch the Buildroot tree at all, and still be able to get in
compliance by providing only that br2-external tree(s) that contains
FLOSS packages, leaving aside the br2-external tree(s) with the
proprietary bits.

What we do is to treat BR2_EXTERNAL as a colon-separated (space-
separated also work, and we use that internally) list of paths, on which
we iterate to construct:

  - the list of all br2-external names, BR2_EXTERNAL_NAMES,

  - the per-br2-external tree BR2_EXTERNAL_$(NAME) variables, which
    point each to the actual location of the corresponding tree,

  - the list of paths to all the external.mk files, BR2_EXTERNAL_MKS,

  - the space-separated list of absolute paths to the external trees,
    BR2_EXTERNAL_DIRS.

Once we have all those variables, we replace references to BR2_EXTERNAL
with either one of those.

This cascades into how we display the list of defconfigs, so that it is
easy to see what br2-external tree provides what defconfigs. As
suggested by Arnout, tweak the comment from "User-provided configs" to
"External configs", on the assumption that some br2-external trees could
be provided by vendors, so not necessarily user-provided. Ditto the menu
in Kconfig, changed from "User-provided options" to "External options".

Now, when more than one br2-external tree is used, each gets its own
sub-menu in the "User-provided options" menu. The sub-menu is labelled
with that br2-external tree's name and the sub-menu's first item is a
comment with the path to that br2-external tree.

If there's only one br2-external tree, then there is no sub-menu; there
is a single comment that contains the name and path to the br2-external
tree.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Romain Naour <romain.naour@openwide.fr>
Cc: Julien CORJON <corjon.j@ecagroup.com>
---
 Makefile                     |  57 +++++++++++++---------
 package/pkg-generic.mk       |   4 +-
 support/scripts/br2-external | 112 +++++++++++++++++++++++++++++--------------
 3 files changed, 113 insertions(+), 60 deletions(-)

Dear Yann,

Le 05/09/2016 à 23:49, Yann E. MORIN a écrit :
> Currently, we only support at most one br2-external tree. Being able
> to use more than one br2-external tree can be very useful.
>
> A use-case would be for having a br2-external to contain the basic
> packages, basic board defconfigs and board files, provided by one team
> responsible for the "board-bringup", while other teams consume that
> br2-external as a base, and complements it each with their own set of
> packages, defconfigs and extra board files.
>
> Another use-case would be for third-parties to provide their own
> Buildroot packaging in a br2-external tree, along-side the archives for
> their stuff.
>
> Finally, another use-case is to be able to add FLOSS packages in a
> br2-external tree, and proprietary packages in another. This allows
> to not touch the Buildroot tree at all, and still be able to get in
> compliance by providing only that br2-external tree(s) that contains
> FLOSS packages, leaving aside the br2-external tree(s) with the
> proprietary bits.
>
> What we do is to treat BR2_EXTERNAL as a colon-separated (space-
> separated also work, and we use that internally) list of paths, on which
> we iterate to construct:
>
>   - the list of all br2-external names, BR2_EXTERNAL_NAMES,
>
>   - the per-br2-external tree BR2_EXTERNAL_$(NAME) variables, which
>     point each to the actual location of the corresponding tree,
>
>   - the list of paths to all the external.mk files, BR2_EXTERNAL_MKS,
>
>   - the space-separated list of absolute paths to the external trees,
>     BR2_EXTERNAL_DIRS.
>
> Once we have all those variables, we replace references to BR2_EXTERNAL
> with either one of those.
>
> This cascades into how we display the list of defconfigs, so that it is
> easy to see what br2-external tree provides what defconfigs. As
> suggested by Arnout, tweak the comment from "User-provided configs" to
> "External configs", on the assumption that some br2-external trees could
> be provided by vendors, so not necessarily user-provided. Ditto the menu
> in Kconfig, changed from "User-provided options" to "External options".
>
> Now, when more than one br2-external tree is used, each gets its own
> sub-menu in the "User-provided options" menu. The sub-menu is labelled
> with that br2-external tree's name and the sub-menu's first item is a
> comment with the path to that br2-external tree.
>
> If there's only one br2-external tree, then there is no sub-menu; there
> is a single comment that contains the name and path to the br2-external
> tree.
>
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: Arnout Vandecappelle <arnout@mind.be>
> Cc: Romain Naour <romain.naour@openwide.fr>
> Cc: Julien CORJON <corjon.j@ecagroup.com>
> ---
>  Makefile                     |  57 +++++++++++++---------
>  package/pkg-generic.mk       |   4 +-
>  support/scripts/br2-external | 112 +++++++++++++++++++++++++++++--------------
>  3 files changed, 113 insertions(+), 60 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 74ed266..c0edb00 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -143,7 +143,7 @@ $(if $(BASE_DIR),, $(error output directory "$(O)" does not exist))
>  # Handling of BR2_EXTERNAL.
>  #
>  # The value of BR2_EXTERNAL is stored in .br-external in the output directory.
> -# The location of the external.mk makefile fragment is computed in that file.
> +# The location of the external.mk makefile fragments is computed in that file.
>  # On subsequent invocations of make, this file is read in. BR2_EXTERNAL can
>  # still be overridden on the command line, therefore the file is re-created
>  # every time make is run.
> @@ -454,16 +454,15 @@ include boot/common.mk
>  include linux/linux.mk
>  include fs/common.mk
>
> -# If using a br2-external tree, the BR2_EXTERNAL_$(NAME)_PATH variable
> -# is also present in the .config file. Since .config is included after
> -# we defined BR2_EXTERNAL_$(NAME)_PATH in the Makefile, the value in
> -# that variable is quoted. We just include the generated Makefile fragment
> -# .br2-external.mk a third time, which will set that variable to the
> -# un-quoted value.
> +# If using a br2-external tree, the BR2_EXTERNAL_$(NAME)_PATH variables
> +# are also present in the .config file. Since .config is included after
> +# we defined them in the Makefile, the values for those variables are
> +# quoted. We just include the generated Makefile fragment .br2-external.mk
> +# a third time, which will set those variables to the un-quoted values.
>  include $(BR2_EXTERNAL_FILE)
>
>  # Nothing to include if no BR2_EXTERNAL tree in use
> -include $(BR2_EXTERNAL_MK)
> +include $(BR2_EXTERNAL_MKS)
>
>  # Now we are sure we have all the packages scanned and defined. We now
>  # check for each package in the list of enabled packages, that all its
> @@ -858,7 +857,7 @@ define percent_defconfig
>  	@$$(COMMON_CONFIG_ENV) BR2_DEFCONFIG=$(1)/configs/$$@ \
>  		$$< --defconfig=$(1)/configs/$$@ $$(CONFIG_CONFIG_IN)
>  endef
> -$(eval $(foreach d,$(TOPDIR) $(if $(BR2_EXTERNAL_NAME),$(BR2_EXTERNAL_$(BR2_EXTERNAL_NAME)_PATH)),$(call percent_defconfig,$(d))$(sep)))
> +$(eval $(foreach d,$(TOPDIR) $(BR2_EXTERNAL_DIRS),$(call percent_defconfig,$(d))$(sep)))
>
>  savedefconfig: $(BUILD_DIR)/buildroot-config/conf prepare-kconfig
>  	@$(COMMON_CONFIG_ENV) $< \
> @@ -984,19 +983,33 @@ help:
>  	@echo 'it on-line at http://buildroot.org/docs.html'
>  	@echo
>
> +# List the defconfig files
> +# $(1): base directory
> +# $(2): br2-external name, empty for bundled
> +define list-defconfigs
> +	@first=y; \
> +	for defconfig in $(1)/configs/*_defconfig; do \
> +		[ -f "$${defconfig}" ] || continue; \
> +		if [ "$${first}" ]; then \
> +			if [ "$(2)" ]; then \
> +				printf "External configs in $(2):\n"; \
> +			else \
> +				printf "Built-in configs:\n"; \
> +			fi; \
> +			first=; \
> +		fi; \
> +		defconfig="$${defconfig##*/}"; \
> +		printf "  %-35s - Build for %s\n" "$${defconfig}" "$${defconfig%_defconfig}"; \
> +	done;\
> +	printf "\n"
> +endef
> +
> +# We iterate over BR2_EXTERNAL_NAMES rather than BR2_EXTERNAL_DIRS,
> +# because we want to display the name of the br2-external tree.
>  list-defconfigs:
> -	@echo 'Built-in configs:'
> -	@$(foreach b, $(sort $(notdir $(wildcard $(TOPDIR)/configs/*_defconfig))), \
> -	  printf "  %-35s - Build for %s\\n" $(b) $(b:_defconfig=);)
> -ifneq ($(BR2_EXTERNAL_NAME),)
> -ifneq ($(wildcard $(BR2_EXTERNAL_$(BR2_EXTERNAL_NAME)_PATH)/configs/*_defconfig),)
> -	@echo
> -	@echo 'User-provided configs:'
> -	@$(foreach b, $(sort $(notdir $(wildcard $(BR2_EXTERNAL_$(BR2_EXTERNAL_NAME)_PATH)/configs/*_defconfig))), \
> -	  printf "  %-35s - Build for %s\\n" $(b) $(b:_defconfig=);)
> -endif
> -endif
> -	@echo
> +	$(call list-defconfigs,$(TOPDIR))
> +	$(foreach name,$(BR2_EXTERNAL_NAMES),\
> +		$(call list-defconfigs,$(BR2_EXTERNAL_$(name)_PATH),$(name))$(sep))
>
>  release: OUT = buildroot-$(BR2_VERSION)
>
> @@ -1015,7 +1028,7 @@ print-version:
>  	@echo $(BR2_VERSION_FULL)
>
>  include docs/manual/manual.mk
> --include $(if $(BR2_EXTERNAL_NAME),$(BR2_EXTERNAL_$(BR2_EXTERNAL_NAME)_PATH)/docs/*/*.mk)
> +-include $(foreach dir,$(BR2_EXTERNAL_DIRS),$(dir)/docs/*/*.mk)
>
>  .PHONY: $(noconfig_targets)
>
> diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
> index 946244e..0737fa1 100644
> --- a/package/pkg-generic.mk
> +++ b/package/pkg-generic.mk
> @@ -767,9 +767,9 @@ $$($(2)_TARGET_DIRCLEAN):		PKG=$(2)
>  # kernel case, the bootloaders case, and the normal packages case.
>  ifeq ($(1),linux)
>  $(2)_KCONFIG_VAR = BR2_LINUX_KERNEL
> -else ifneq ($$(filter boot/% $$(if $$(BR2_EXTERNAL_NAME),$$(BR2_EXTERNAL_$$(BR2_EXTERNAL_NAME)_PATH)/boot/%),$(pkgdir)),)
> +else ifneq ($$(filter boot/% $$(foreach dir,$$(BR2_EXTERNAL_DIRS),$$(dir)/boot/%),$(pkgdir)),)
>  $(2)_KCONFIG_VAR = BR2_TARGET_$(2)
> -else ifneq ($$(filter toolchain/% $$(if $$(BR2_EXTERNAL_NAME),$$(BR2_EXTERNAL_$$(BR2_EXTERNAL_NAME)_PATH)/toolchain/%),$(pkgdir)),)
> +else ifneq ($$(filter toolchain/% $$(foreach dir,$$(BR2_EXTERNAL_DIRS),$$(dir)/toolchain/%),$(pkgdir)),)
>  $(2)_KCONFIG_VAR = BR2_$(2)
>  else
>  $(2)_KCONFIG_VAR = BR2_PACKAGE_$(2)
> diff --git a/support/scripts/br2-external b/support/scripts/br2-external
> index 18e547e..9936650 100755
> --- a/support/scripts/br2-external
> +++ b/support/scripts/br2-external
> @@ -1,9 +1,9 @@
>  #!/bin/bash
>  set -e
>
> -# The name and location of the br2-external tree, once validated.
> -declare BR2_NAME
> -declare BR2_EXT
> +# The names and locations of the br2-external trees, once validated.
> +declare -a BR2_EXT_NAMES
> +declare -A BR2_EXT_PATHS
>
>  main() {
>      local OPT OPTARG
> @@ -22,8 +22,6 @@ main() {
>      # Forget options; keep only positional args
>      shift $((OPTIND-1))
>
> -    br2_ext="${1}"
> -
>      case "${ofmt}" in
>      mk)
>          error() {
> @@ -43,13 +41,14 @@ main() {
>
>      exec >"${ofile}"
>
> -    do_validate "${br2_ext}"
> +    do_validate ${@//:/ }
>
>      do_${ofmt}
>  }
>
> -# Validates the br2-external tree passed as argument. Makes it cannonical
> -# and store it in global variable BR2_EXT.
> +# Validates the br2-external trees passed as arguments. Makes each of
> +# then canonical and store them in the global arrays BR2_EXT_NAMES

s/then/them/g

Regards,

Julien Corjon

> +# and BR2_EXT_PATHS.
>  #
>  # Note: since this script is always first called from Makefile context
>  # to generate the Makefile fragment before it is called to generate the
> @@ -58,14 +57,22 @@ main() {
>  # snippet means that there were no error.
>  #
>  do_validate() {
> +    local br2_ext
> +
> +    if [ ${#} -eq 0 ]; then
> +        # No br2-external tree is valid
> +        return
> +    fi
> +
> +    for br2_ext in "${@}"; do
> +        do_validate_one "${br2_ext}"
> +    done
> +}
> +
> +do_validate_one() {
>      local br2_ext="${1}"
>      local br2_name n
>
> -    # No br2-external tree is valid
> -    if [ -z "${br2_ext}" ]; then
> -        return
> -    fi
> -
>      if [ ! -d "${br2_ext}" ]; then
>          error "'%s': no such file or directory\n" "${br2_ext}"
>      fi
> @@ -83,6 +90,10 @@ do_validate() {
>          error "'%s': name '%s' contains invalid chars: '%s'\n" \
>              "${br2_ext}" "${br2_name//\$/\$\$}" "${n//\$/\$\$}"
>      fi
> +    if [ -n "${BR2_EXT_PATHS["${br2_name}"]}" ]; then
> +        error "'%s': name '%s' is already used in '%s'\n" \
> +            "${br2_ext}" "${br2_name}" "${BR2_EXT_PATHS["${br2_name}"]}"
> +    fi
>      if [ ! -f "${br2_ext}/external.mk" ]; then
>          error "'%s/external.mk': no such file or directory\n" "${br2_ext}"
>      fi
> @@ -90,51 +101,80 @@ do_validate() {
>          error "'%s/Config.in': no such file or directory\n" "${br2_ext}"
>      fi
>
> -    BR2_NAME="${br2_name}"
> -    BR2_EXT="$(cd "${br2_ext}"; pwd -P )"
> +    # Register this br2-external tree
> +    BR2_EXT_NAMES+=( "${br2_name}" )
> +    BR2_EXT_PATHS["${br2_name}"]="${br2_ext}"
>  }
>
>  # Generate the .mk snippet that defines makefile variables
>  # for the br2-external tree
>  do_mk() {
> +    local br2_name br2_ext
> +
>      printf '#\n# Automatically generated file; DO NOT EDIT.\n#\n'
>      printf '\n'
>
> -    printf 'BR2_EXTERNAL ?= %s\n' "${BR2_EXT}"
> -    printf 'BR2_EXTERNAL_NAME = \n'
> -    printf 'BR2_EXTERNAL_MK =\n'
> +    # We can't use ${BR2_EXT_NAMES[@]} directly: it is not guaranteed
> +    # to be in the order paths were added (because it is an associative
> +    # array). So we need to iterate on BR2_EXT_NAMES, which is sorted
> +    # in the order names were added (because it is an indexed array).
> +    printf 'BR2_EXTERNAL ?='
> +    for br2_name in "${BR2_EXT_NAMES[@]}"; do
> +        printf ' %s' "${BR2_EXT_PATHS["${br2_name}"]}"
> +    done
>      printf '\n'
>
> -    if [ -z "${BR2_NAME}" ]; then
> +    printf 'BR2_EXTERNAL_NAMES = \n'
> +    printf 'BR2_EXTERNAL_DIRS = \n'
> +    printf 'BR2_EXTERNAL_MKS = \n'
> +
> +    if [ ${#BR2_EXT_NAMES[@]} -eq 0 ]; then
> +        printf '\n'
>          printf '# No br2-external tree defined.\n'
>          return
>      fi
>
> -    printf 'BR2_EXTERNAL_NAME = %s\n' "${BR2_NAME}"
> -    printf 'BR2_EXTERNAL_MK = %s/external.mk\n' "${BR2_EXT}"
> -    printf 'BR2_EXTERNAL_%s_PATH = %s\n' "${BR2_NAME}" "${BR2_EXT}"
> +    for br2_name in "${BR2_EXT_NAMES[@]}"; do
> +        br2_ext="${BR2_EXT_PATHS["${br2_name}"]}"
> +        printf '\n'
> +        printf 'BR2_EXTERNAL_NAMES += %s\n' "${br2_name}"
> +        printf 'BR2_EXTERNAL_%s_PATH = %s\n' "${br2_name}" "${br2_ext}"
> +        printf 'BR2_EXTERNAL_DIRS += %s\n' "${br2_ext}"
> +        printf 'BR2_EXTERNAL_MKS += %s/external.mk\n' "${br2_ext}"
> +    done
>  }
>
>  # Generate the kconfig snippet for the br2-external tree.
>  do_kconfig() {
> +    local br2_name br2_ext
> +
>      printf '#\n# Automatically generated file; DO NOT EDIT.\n#\n'
>      printf '\n'
>
> -    if [ -z "${BR2_NAME}" ]; then
> +    if [ ${#BR2_EXT_NAMES[@]} -eq 0 ]; then
>          printf '# No br2-external tree defined.\n'
>          return
>      fi
>
> -    printf 'menu "User-provided options"\n'
> -    printf '\n'
> -    printf 'comment "%s (in %s)"\n' "${BR2_NAME}" "${BR2_EXT}"
> -    printf '\n'
> -    printf 'config BR2_EXTERNAL_%s_PATH\n' "${BR2_NAME}"
> -    printf '\tstring\n'
> -    printf '\tdefault "%s"\n' "${BR2_EXT}"
> -    printf '\n'
> -    printf 'source "$BR2_EXTERNAL_%s_PATH/Config.in"\n' "${BR2_NAME}"
> +    printf 'menu "External options"\n'
>      printf '\n'
> +
> +    for br2_name in "${BR2_EXT_NAMES[@]}"; do
> +        br2_ext="${BR2_EXT_PATHS["${br2_name}"]}"
> +        if [ ${#BR2_EXT_NAMES[@]} -gt 1 ]; then
> +            printf 'menu "%s"\n' "${br2_name}"
> +        fi
> +        printf 'comment "%s (in %s)"\n' "${br2_name}" "${br2_ext}"
> +        printf 'config BR2_EXTERNAL_%s_PATH\n' "${br2_name}"
> +        printf '\tstring\n'
> +        printf '\tdefault "%s"\n' "${br2_ext}"
> +        printf 'source "%s/Config.in"\n' "${br2_ext}"
> +        if [ ${#BR2_EXT_NAMES[@]} -gt 1 ]; then
> +            printf 'endmenu # %s\n' "${br2_name}"
> +        fi
> +        printf '\n'
> +    done
> +
>      printf "endmenu # User-provided options\n"
>  }
>
> @@ -144,12 +184,12 @@ help() {
>  	    ${my_name} <-m|-k> -o FILE PATH
>
>  	With -m, ${my_name} generates the makefile fragment that defines
> -	variables related to the br2-external tree passed as positional
> -	argument.
> +	variables related to the br2-external trees passed as positional
> +	arguments.
>
>  	With -k, ${my_name} generates the kconfig snippet to include the
> -	configuration options specified in the br2-external tree passed
> -	as positional argument.
> +	configuration options specified in the br2-external trees passed
> +	as positional arguments.
>
>  	Using -k and -m together is not possible. The last one wins.
>
>