[Buildroot] [PATCH 1/2] support/dependencies: add a check for python3

[Adam Duskett]

Hello;
On Sun, Mar 10, 2019 at 12:59 PM Romain Naour <romain.naour at gmail.com> wrote:
>
> Since version 2.29, glibc requires python 3.4 or later to build the GNU C Library [1].
>
> We add a new check to verify the version of python3 interpreter installed on the host.
> If no suitable python3 interpreter is found, define BR2_PYTHON3_HOST_DEPENDENCY to add
> host-python3 in package dependencies when needed.
>
> [1] https://www.sourceware.org/ml/libc-alpha/2019-01/msg00723.html
>
> Signed-off-by: Romain Naour <romain.naour at gmail.com>
> ---
>  support/dependencies/check-host-python3.mk | 13 ++++++++++
>  support/dependencies/check-host-python3.sh | 41 ++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+)
>  create mode 100644 support/dependencies/check-host-python3.mk
>  create mode 100755 support/dependencies/check-host-python3.sh
>
> diff --git a/support/dependencies/check-host-python3.mk b/support/dependencies/check-host-python3.mk
> new file mode 100644
> index 0000000000..ceb48c969e
> --- /dev/null
> +++ b/support/dependencies/check-host-python3.mk
> @@ -0,0 +1,13 @@
> +# Since version 2.29, glibc requires python 3.4 or later to build the GNU C Library.
> +# https://www.sourceware.org/ml/libc-alpha/2019-01/msg00723.html
> +
> +# Set this to either 3.4 or higher, depending on the highest minimum
> +# version required by any of the packages bundled in Buildroot. If a
> +# package is bumped or a new one added, and it requires a higher
> +# version, our package infra will catch it and whine.
> +#
> +BR2_PYTHON3_VERSION_MIN = 3.4
> +
> +ifeq (,$(call suitable-host-package,python3,$(BR2_PYTHON3_VERSION_MIN) python3 python))
> +BR2_PYTHON3_HOST_DEPENDENCY = host-python3
> +endif
> diff --git a/support/dependencies/check-host-python3.sh b/support/dependencies/check-host-python3.sh
> new file mode 100755
> index 0000000000..e5745fa7c4
> --- /dev/null
> +++ b/support/dependencies/check-host-python3.sh
> @@ -0,0 +1,41 @@
> +#!/bin/sh
> +
> +# prevent shift error
> +[ $# -lt 2 ] && exit 1
> +
> +major_min="${1%.*}"
> +minor_min="${1#*.}"
> +
> +shift
> +
> +# The host python interpreter is already checked by dependencies.sh but
> +# it only check if the version is at least 2.7.
> +# We want to check the version number of the python3 interpreter even
> +# if Buildroot is able to use any version but some packages may require
> +# a more recent version.
> +python3_candidates="$1"
> +
> +for candidate in $python3_candidates ; do
> +       python3=`which $candidate 2>/dev/null`
> +       if [ ! -x "$python3" ]; then
> +               continue
> +       fi
> +       version=`$python3 -V 2>&1 | sed -e 's/^.* \([0-9\.]\)/\1/g' -e 's/[-].*//g' -e '1q'`
I personally prefer the syntax foo=$(command) rather than foo=`$command`
> +
> +       major=`echo "$version" | cut -d. -f1`
> +       minor=`echo "$version" | cut -d. -f2`
> +
I have a bit of issue with this:
Why can't we use the same line as we use in dependencies.sh?
version=$(python3 -V 2>&1 |awk '{ split($2, v, "."); print v[1] v[2] }')
On Fedora29 this produces 37, which makes the check much easier.

> +       if [ $major -lt $major_min ]; then
> +               # no suitable python3 found
> +               continue
> +       fi
> +
> +       if [ $major -eq $major_min -a $minor -lt $minor_min ]; then
> +               # no suitable python3 found
> +               continue
> +       fi
> +
> +       # suitable python3 found
> +       echo $python3
> +       break
> +done
> --
> 2.14.5
Is there a reason this logic can't go in dependencies.sh?

>
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Thanks!
Adam