[libcamera-devel] [PATCH v2 1/1] build: Preserve upstream git versioning using meson dist

[Laurent Pinchart]

Hi Naush,

(CC'ing Kieran)

Thank you for the patch.

On Wed, Oct 13, 2021 at 01:23:12PM +0100, Naushir Patuck wrote:
> When distributions build and package libcamera libraries, they may not
> necessarily run the build in the upstream source tree. In these cases, the git
> SHA1 versioning information will be lost.
> 
> This change addresses that problem by requiring package managers to run
> 'meson dist' to create a tarball of the source files and build from there.
> On runing 'meson dist', the utils/run-dist.sh script will create a version.gen
> file in the release tarball with the version string generated from the existing
> utils/gen-version.sh script.
> 
> The utils/gen-version.sh script has been updated to check for the presence of
> this version.gen file and read the version string from it instead of creating
> one.

I came across
https://sources.debian.org/src/libsmpp34/1.14.0-2/git-version-gen/ which
seems to store the version in a file named .tarball-version. Should we
follow the same convention ?

> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  meson.build               |  3 +++
>  src/libcamera/meson.build | 11 +++++------
>  utils/gen-version.sh      |  9 +++++++++
>  utils/run-dist.sh         | 11 +++++++++++
>  4 files changed, 28 insertions(+), 6 deletions(-)
>  create mode 100644 utils/run-dist.sh
> 
> diff --git a/meson.build b/meson.build
> index a49c484fe64e..85ca0013733e 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -24,6 +24,9 @@ endif
>  
>  libcamera_version = libcamera_git_version.split('+')[0]
>  
> +# This script gererates the version.gen file on a 'meson dist' command.
> +meson.add_dist_script('utils/run-dist.sh')
> +
>  # Configure the build environment.
>  cc = meson.get_compiler('c')
>  cxx = meson.get_compiler('cpp')
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 243dd3c180eb..360eaf80ecf1 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -93,12 +93,11 @@ endforeach
>  
>  libcamera_sources += control_sources
>  
> -gen_version = meson.source_root() / 'utils' / 'gen-version.sh'
> -
> -version_cpp = vcs_tag(command : [gen_version, meson.build_root()],
> -                      input : 'version.cpp.in',
> -                      output : 'version.cpp',
> -                      fallback : meson.project_version())
> +version_data = configuration_data()
> +version_data.set('VCS_TAG', libcamera_git_version)
> +version_cpp = configure_file(input : 'version.cpp.in',
> +                             output : 'version.cpp',
> +                             configuration : version_data)

This doesn't seem strictly needed, but it avoids running gen-version.sh
a second time, which is nice. I however have a nagging feeling that
there was a reason why we used vcs_tag and not configure_file, but I
can't recall it. We'll find out if it causes issues :-)

>  
>  libcamera_sources += version_cpp
>  
> diff --git a/utils/gen-version.sh b/utils/gen-version.sh
> index b09ad495f86a..09cede84c25e 100755
> --- a/utils/gen-version.sh
> +++ b/utils/gen-version.sh
> @@ -5,6 +5,15 @@
>  
>  build_dir="$1"
>  
> +# If version.gen exists, output the version string from the file and exit.
> +# This file is auto-generated on a 'meson dist' command from the run-dist.sh
> +# script.
> +if [ -f "${MESON_SOURCE_ROOT}"/version.gen ]
> +then
> +	cat "${MESON_SOURCE_ROOT}"/version.gen
> +	exit 0
> +fi
> +

Shouldn't we do this only if we're not under git control ? There should
be no version.gen file in that case of course, but isn't still a better
default ?

>  # Bail out if the directory isn't under git control
>  src_dir=$(git rev-parse --git-dir 2>&1) || exit 1
>  src_dir=$(readlink -f "$src_dir/..")
> diff --git a/utils/run-dist.sh b/utils/run-dist.sh
> new file mode 100644
> index 000000000000..3b6c0adb05ed
> --- /dev/null
> +++ b/utils/run-dist.sh
> @@ -0,0 +1,11 @@
> +#!/bin/sh
> +
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +#
> +# On a meson dist run, generate the version string and store it in a file.
> +# This will later be picked up by the utils/gen-version.sh script and used
> +# instead of re-generating it. This way, if we are not building in the upstream
> +# git source tree, the upstream version information will be preserved.
> +
> +cd "$MESON_SOURCE_ROOT" || return
> +./utils/gen-version.sh > "$MESON_DIST_ROOT"/version.gen

Do we need to handle the case of meson dist being run from a tarball
instead of git ? It seems like a corner case to me, so probably not very
useful, but we could possibly support it by copying
$MESON_SOURCE_ROOT/version.gen to $MESON_DIST_ROOT/ if the source file
exists. I'm fine either way.

-- 
Regards,

Laurent Pinchart