bindings: python: add a script to generate armv7l wheels

bindings/python/README.md

@@ -56,6 +56,14 @@ If you still need the deprecated pure-Python bindings, install with:
 pip install gpiod==1.5.4
 ```
 
+Pre-built binary `manylinux` and `musllinux` wheels are published to PyPI.org
+for selected platforms, to speed up installation. `armv7l` users: Note that the
+pre-built armv7l wheels make use of the VFP instruction set extension (a.k.a.
+hard float). If your system does not support VFP, `pip install` will rebuild the
+wheel from source on a `manylinux` system, but possibly not on a `musllinux`
+system. If you have a musl-libc-based armv7l system without VFP support and you
+come across issues using the pre-built gpiod wheel, please get in touch.
+
 ## Examples
 
 Check a GPIO chip character device exists:

bindings/python/generate_armv7l_wheels.sh

@@ -0,0 +1,158 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2024 Paulo Ferreira de Castro <[email protected]>
+#
+# This script makes armv7l gpiod Python wheels for combinations of libc (glibc
+# and musl) and CPython versions, complementing the wheels made by cibuildwheel
+# (through the 'generate_pypi_artifacts.sh' script).
+#
+# Modify the TARGET_PYTHON_VERSIONS global variable below in order to change
+# the targeted CPython versions.
+#
+# Dependencies: Docker and binfmt_misc for ARM emulation.
+#
+# Usage:
+# ./generate_armv7l_wheels.sh
+#
+# The wheels will be placed in the ./dist directory.
+#
+
+TARGET_PYTHON_VERSIONS=(3.9 3.10 3.11 3.12)
+TARGET_ARCH='armv7l'
+
+# Docker image used to run Python commands locally (whichever host CPU).
+NATIVE_PYTHON_IMG="python:3.12-alpine"
+
+quit() {
+	echo -e "\n${1}"
+	exit 1
+}
+
+# Print the gpiod Python binding version from gpiod/version.py.
+print_gpiod_version() {
+	set -x
+	docker run --rm -iv "${PWD}/gpiod:/gpiod" "${NATIVE_PYTHON_IMG}" python <<-EOF
+		import sys
+		sys.path.insert(0, "/gpiod")
+		from version import __version__
+		print(__version__)
+	EOF
+	{ local status="$?"; set +x; } 2>/dev/null
+	return "${status}"
+}
+
+# Make the sdist if it does not already exist in the './dist' directory.
+ensure_sdist() {
+	local gpiod_version
+	gpiod_version="$(print_gpiod_version)" || \
+		quit "Failed to determine the gpiod Python binding version"
+
+	SDIST_TARBALL="gpiod-${gpiod_version}.tar.gz"
+	if [ -f "dist/${SDIST_TARBALL}" ]; then
+		return
+	fi
+	if [ -z "${LIBGPIOD_VERSION}" ]; then
+		quit "Please set the LIBGPIOD_VERSION env var to enable making the sdist."
+	fi
+	set -x
+	docker run --rm -v "${PWD}:/py_bindings" -w /py_bindings -e LIBGPIOD_VERSION \
+		"${NATIVE_PYTHON_IMG}" python setup.py sdist
+	{ local status="$?"; set +x; } 2>/dev/null
+	return "${status}"
+}
+
+# Set the BASE_IMG array with details of the Docker image used to build wheels.
+set_base_img_array() {
+	local libc="$1" # The string 'glibc' or 'musl'
+	declare -Ag BASE_IMG
+	case "${libc}" in
+		glibc)	BASE_IMG[name]='python'
+				BASE_IMG[distro]='bullseye'
+				BASE_IMG[platform]='linux/arm/v7'
+				BASE_IMG[wheel_plat]="manylinux_2_17_${TARGET_ARCH}"
+				BASE_IMG[deps]="
+RUN apt-get update && apt-get install -y autoconf-archive
+# auditwheel requires patchelf v0.14+, but Debian Bullseye comes with v0.12.
+RUN curl -Ls 'https://github.com/NixOS/patchelf/releases/download/0.18.0/patchelf-0.18.0-${TARGET_ARCH}.tar.gz' \
+	| tar -xzC /usr ./bin/patchelf
+";;
+		musl)	BASE_IMG[name]='python'
+				BASE_IMG[distro]='alpine3.20'
+				BASE_IMG[platform]='linux/arm/v7'
+				BASE_IMG[wheel_plat]="musllinux_1_2_${TARGET_ARCH}"
+				BASE_IMG[deps]="
+RUN apk add autoconf autoconf-archive automake bash binutils curl \
+	g++ git libtool linux-headers make patchelf pkgconfig
+";;
+	esac
+}
+
+# Make a "wheel builder" docker image used to build gpiod wheels.
+# The base image is the official Python image on Docker Hub, in either the
+# Debian variant (glibc) or the Alpine variant (musl). Currently using
+# Debian 11 Bullseye because it supports building wheels targeting glibc
+# v2.17. The newer Debian 12 Bookworm supports higher glibc versions only.
+make_wheel_builder_image() {
+	local builder_img_tag="$1"
+	local python_version="$2"
+	set -x
+	docker build --platform "${BASE_IMG[platform]}" --pull --progress plain \
+		--tag "${builder_img_tag}" --file - . <<-EOF
+			FROM '${BASE_IMG[name]}:${python_version}-${BASE_IMG[distro]}'
+			${BASE_IMG[deps]}
+			RUN pip install auditwheel
+		EOF
+	{ local status="$?"; set +x; } 2>/dev/null
+	return "${status}"
+}
+
+# Build a gpiod wheel in a container of the given builder image tag.
+build_wheel() {
+	local builder_img_tag="$1"
+	set -x
+	docker run --rm --platform "${BASE_IMG[platform]}" -iv "${PWD}/dist:/dist" \
+		-w /tmp "${builder_img_tag}" bash <<-EOF
+			set -ex
+			pip wheel --no-deps "/dist/${SDIST_TARBALL}"
+			auditwheel repair --plat "${BASE_IMG[wheel_plat]}" --wheel-dir /dist ./*.whl
+		EOF
+	{ local status="$?"; set +x; } 2>/dev/null
+	return "${status}"
+}
+
+# Build gpiod wheels for combinations of libc and Python versions.
+build_combinations() {
+	local builder_img_tag=
+
+	for libc in glibc musl; do
+		set_base_img_array "${libc}"
+
+		for ver in "${TARGET_PYTHON_VERSIONS[@]}"; do
+			builder_img_tag="gpiod-wheel-builder-cp${ver/./}-${libc}-${TARGET_ARCH}"
+
+			make_wheel_builder_image "${builder_img_tag}" "${ver}" || \
+				quit "Failed to build Docker image '${builder_img_tag}'"
+
+			build_wheel "${builder_img_tag}" || \
+				quit "Failed to build gpiod wheel with image '${builder_img_tag}'"
+
+			set -x
+			docker image rm "${builder_img_tag}"
+			{ set +x; } 2>/dev/null
+		done
+	done
+}
+
+main() {
+	set -e
+	local script_dir # Directory where this script is located
+	script_dir="$(cd -- "$(dirname "$0")" >/dev/null 2>&1 || true; pwd -P)"
+	cd "${script_dir}" || quit "'cd ${script_dir}' failed"
+	ensure_sdist || quit "Failed to find or make the sdist tarball."
+	build_combinations
+	echo
+	ls -l dist/*"${TARGET_ARCH}"*
+	echo -e "\nAll done! Hint: Use 'docker system prune' to free disk space."
+}
+
+main