python bindings: fix builds for pre-pyproject setuptools

openSUSE Leap only has setuptools 44, which predates support for
pyproject. This is fine, we just need to add the relevant metadata to
the setuptools invocation. To reduce the amount of places we duplicate
this information, just load pyproject.toml and read the values out (this
does add a dependency on toml for pre-3.11 Python versions but that's
fine).

Signed-off-by: Aleksa Sarai <[email protected]>

Author: cyphar

contrib/bindings/python/pyproject.toml

@@ -17,9 +17,10 @@
 
 [build-system]
 requires = [
-	"setuptools>=68",
+	"cffi>=1.10.0",
+	"setuptools>=61",
+	"toml>=0.10", # TODO: Remove this once we only support Python >= 3.11.
 	"wheel",
-	"cffi>=1.10.0"
 ]
 build-backend = "setuptools.build_meta"
 
@@ -50,7 +51,7 @@ classifiers = [
 
 requires-python = ">= 3.8"
 dependencies = [
-	"cffi>=1.10.0"
+	"cffi>=1.10.0",
 ]
 
 [project.urls]

contrib/bindings/python/setup.py

@@ -17,7 +17,27 @@
 
 import setuptools
 
+# This is only needed for backwards compatibility with older versions.
+def parse_pyproject():
+	try:
+		import tomllib
+		openmode = "rb"
+	except ImportError:
+		# TODO: Remove this once we only support Python >= 3.11.
+		import toml as tomllib
+		openmode = "r"
+
+	with open("pyproject.toml", openmode) as f:
+		return tomllib.load(f)
+
+pyproject = parse_pyproject()
+
 setuptools.setup(
+	# For backwards-compatibility with pre-pyproject setuptools.
+	name=pyproject["project"]["name"],
+	version=pyproject["project"]["version"],
+	install_requires=pyproject["project"]["dependencies"],
+	# Configure cffi building.
 	ext_package="pathrs",
 	platforms=["Linux"],
 	cffi_modules=["pathrs/pathrs_build.py:ffibuilder"],