bindings: python: add script to generate sdist and wheels

Introduce a shell script that generates an sdist tarball and PEP 600/656
conformant wheels.

The wheels are generated via cibuildwheel, a tool provided by the Python
Packaging Authority (PyPA) [0]. The tool leverages toolchains within
containers maintained by PyPA [1] to generate wheels that are runnable
on hosts that meet the platform compatibility tag [2] requirements.

By default, the script creates X86_64 and AArch64 CPython 3.9-3.12
wheels for glibc and musl libc based systems.

These defaults can be overridden via CIBW_* environment variables [3].

[0]: https://cibuildwheel.pypa.io/en/stable/
[1]: https://github.com/pypa/manylinux/
[2]: https://packaging.python.org/en/latest/specifications/platform-compatibility-tags/
[3]: https://cibuildwheel.pypa.io/en/stable/options/#options-summary

Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Link: https://lore.kernel.org/r/20240611205041.1448276-1-vfazio@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

diff --git a/bindings/python/generate_pypi_artifacts.sh b/bindings/python/generate_pypi_artifacts.sh
new file mode 100755 (executable)
index 0000000..c2fb79f
--- /dev/null
+++ b/bindings/python/generate_pypi_artifacts.sh
@@ -0,0 +1,134 @@
+#!/usr/bin/env sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2024 Vincent Fazio <vfazio@gmail.com>
+#
+# This is a script to generate an sdist and wheels for publishing to PyPI.
+#
+# This script requires:
+#   * Python3 + venv or virtualenv + pip
+#   * Docker or Podman (https://cibuildwheel.pypa.io/en/stable/options/#container-engine)
+#   * binfmt support and qemu-user-static for AArch64 registered as Fixed
+#     (https://docs.kernel.org/admin-guide/binfmt-misc.html)
+#
+# On Debian based systems, AArch64 binfmt support can be checked via:
+#   cat /proc/sys/fs/binfmt_misc/qemu-aarch64
+#
+# The entry should be enabled and "F" should be in the list of flags.
+#
+
+usage()
+{
+       printf "\n"
+       printf "Usage: %s -v <libgpiod_source_version> [-o <output_directory>] [-s <source_directory>] [-cfh]\n" "$0"
+       printf "\t-v Version of libgpiod sources to bundle in sdist. Overrides LIBGPIOD_VERSION\n"
+       printf "\t-o Directory to store outputs\n"
+       printf "\t-s Directory with python binding sources\n"
+       printf "\t-c Calculate checksums for generated outputs\n"
+       printf "\t-f Forcibly remove old files from output directory\n"
+       printf "\t-h Show this help output\n"
+       exit 1
+}
+
+src_version=${LIBGPIOD_VERSION:-} # Default to environment specified library version
+output_dir=$(pwd) # Default to putting outputs in the current directory
+source_dir=$(pwd) # Assume the current directory has the python binding sources
+calc_hash=0 # Do not calculate hashes by default
+force=0 # Do not forcibly remove files by default
+
+while getopts :hv:o:s:cf value; do
+       case ${value} in
+               c)
+                       calc_hash=1
+                       ;;
+               f)
+                       force=1
+                       ;;
+               o)
+                       output_dir=${OPTARG}
+                       ;;
+               s)
+                       source_dir=${OPTARG}
+                       ;;
+               v)
+                       src_version=${OPTARG}
+                       ;;
+               h | *)
+                       usage
+                       ;;
+       esac
+done
+
+if [ -z "${source_dir}" ] || [ ! -d "${output_dir}" ]; then
+       printf "Invalid source directory %s.\n" "${source_dir}"
+       exit 1
+fi
+
+if [ -z "${output_dir}" ] || [ ! -w "${output_dir}" ]; then
+       printf "Output directory %s is not writable.\n" "${output_dir}"
+       exit 1
+fi
+
+if [ -z "${src_version}" ]; then
+       printf "The libgpiod source version must be specified.\n"
+       exit 1
+fi
+
+shift $((OPTIND-1))
+
+# We require Python3 for building artifacts
+if ! command -v python3 >/dev/null 2>&1; then
+       printf "Python3 is required to generate PyPI artifacts.\n"
+       exit 1
+fi
+
+# Pip is necessary for installing build dependencies
+if ! python3 -m pip -h >/dev/null 2>&1; then
+       printf "The pip module is required to generate wheels.\n"
+       exit 1
+fi
+
+# Check for a virtual environment tool to not pollute user installed packages
+has_venv=$(python3 -m venv -h >/dev/null 2>&1 && echo 1 || echo 0)
+has_virtualenv=$(python3 -m virtualenv -h >/dev/null 2>&1 && echo 1 || echo 0)
+
+if ! { [ "${has_venv}" -eq 1 ] || [ "${has_virtualenv}" -eq 1 ]; }; then
+       printf "A virtual environment module is required to generate wheels.\n"
+       exit 1
+fi
+
+venv_module=$([ "${has_virtualenv}" -eq 1 ] && echo "virtualenv" || echo "venv" )
+
+# Stage the build in a temp directory.
+cur_dir=$(pwd)
+temp_dir=$(mktemp -d)
+cd "${temp_dir}" || { printf "Failed to enter temp directory.\n"; exit 1; }
+
+# Setup a virtual environment
+python3 -m "${venv_module}" .venv
+venv_python="${temp_dir}/.venv/bin/python"
+
+# Install build dependencies
+# cibuildwheel 2.18.1 pins the toolchain containers to 2024-05-13-0983f6f
+${venv_python} -m pip install build==1.2.1 cibuildwheel==2.18.1
+
+LIBGPIOD_VERSION=${src_version} ${venv_python} -m build --sdist --outdir ./dist "${source_dir}"
+sdist=$(find ./dist -name '*.tar.gz')
+
+# Target only CPython and X86_64 + AArch64 Linux wheels unless specified otherwise via environment variables
+CIBW_BUILD=${CIBW_BUILD:-"cp*"} CIBW_ARCHS=${CIBW_ARCHS:-"x86_64,aarch64"} \
+       ${venv_python} -m cibuildwheel --platform linux "${sdist}" --output-dir dist/
+
+if [ "${force}" -eq 1 ]; then
+       printf "\nRemoving files from %s/dist/\n" "${output_dir}"
+       rm -rf "${output_dir}/dist/"
+fi
+
+cp -fa dist/ "${output_dir}/"
+
+if [ "${calc_hash}" -eq 1 ]; then
+       printf "\nHashes for generated outputs:\n"
+       sha256sum "${output_dir}/dist/"*
+fi
+
+cd "${cur_dir}" || { printf "Failed to return to previous working directory.\n"; exit 1; }
+rm -rf "${temp_dir}"