From 20e168f91742be16fb5d0f7dc8e1a910238f2eb6 Mon Sep 17 00:00:00 2001
From: Daniel Zullo <daniel.zullo@frequenz.com>
Date: Fri, 16 Oct 2026 10:37:08 +0200
Subject: [PATCH] Fix platform tags for libfaketime wheels

The universal wheel lets ARM64 pip install an x86-64 library that
cannot be loaded. Platform tags let pip reject that wheel and use
a compatible wheel or build from source instead.

Keep the library beside its Python package and declare the build
dependencies needed for macOS platform tags.

Fixes #94
---
 CHANGELOG.md       |  1 +
 README.md          |  4 ++++
 pyproject.toml     |  4 ++++
 requirements.txt   |  2 ++
 setup.py           | 24 +++++++++++++++++++++--
 test/test_wheel.py | 47 ++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 80 insertions(+), 2 deletions(-)
 create mode 100644 test/test_wheel.py

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 70ea8e3..edd23b5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ Changelog
 -----
 released ...
 
+- tag wheels for their build platform so pip does not install an incompatible shared library on ARM64
 - breaking: drop support for python 3.9 and 3.10
 - add support for python 3.14
 - upgrade vendored libfaketime to 0.9.13 without modifications, fixing build failures with recent glibc versions and compilers defaulting to ISO C23
diff --git a/README.md b/README.md
index 3b9fd4e..a75d2f6 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,10 @@ Installation
 $ pip install libfaketime
 ```
 
+Wheels contain a native library and are platform-specific. If a compatible wheel
+is not available, installation builds the library from source and requires `make`
+and a C compiler.
+
 Usage
 -----
 
diff --git a/pyproject.toml b/pyproject.toml
index 6d24c6c..91a8b5a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,7 @@
+[build-system]
+requires = ["setuptools>=70.1.0", "wheel"]
+build-backend = "setuptools.build_meta"
+
 [tool.pytest.ini_options]
 filterwarnings = [
     # utcnow() is still covered on purpose: it remains supported and used
diff --git a/requirements.txt b/requirements.txt
index ac49ba8..0caa8b4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,4 +4,6 @@ mock==5.1.0
 pytest==8.2.0
 python-dateutil==2.9.0post0
 pytz==2024.1
+setuptools>=70.1.0
 tox==4.15.0
+wheel
diff --git a/setup.py b/setup.py
index df95baf..841249c 100644
--- a/setup.py
+++ b/setup.py
@@ -5,8 +5,10 @@
 import subprocess
 import sys
 
+from setuptools import Distribution
 from setuptools import find_packages
 from setuptools import setup
+from setuptools.command.bdist_wheel import bdist_wheel
 from setuptools.command.install import install
 
 # This hack is from http://stackoverflow.com/a/7071358/1231454;
@@ -36,6 +38,23 @@
 faketime_lib = os.path.join(_vendor_path, "src", libname)
 
 
+class BinaryDistribution(Distribution):
+    """A distribution containing a platform-specific shared library."""
+
+    def has_ext_modules(self) -> bool:
+        """Use the platform library directory for the bundled native library."""
+        return True
+
+
+class PlatformWheel(bdist_wheel):
+    """A platform-specific wheel without a Python ABI dependency."""
+
+    def get_tag(self) -> tuple[str, str, str]:
+        """Keep Python compatibility while selecting the build platform."""
+        _, _, platform_tag = super().get_tag()
+        return "py3", "none", platform_tag
+
+
 class CustomInstall(install):
     def run(self):
         self.my_outputs = []
@@ -55,7 +74,7 @@ def run(self):
         elif sys.platform == "darwin":
             subprocess.check_call(["make", "-C", _vendor_path])
 
-        dest = os.path.join(self.install_purelib, os.path.dirname(faketime_lib))
+        dest = os.path.join(self.install_lib, os.path.dirname(faketime_lib))
         try:
             os.makedirs(dest)
         except OSError as e:
@@ -106,7 +125,8 @@ def get_outputs(self):
     ],
     include_package_data=True,
     zip_safe=False,
-    cmdclass={"install": CustomInstall},
+    distclass=BinaryDistribution,
+    cmdclass={"bdist_wheel": PlatformWheel, "install": CustomInstall},
     entry_points={
         "console_scripts": [
             "python-libfaketime = libfaketime:main",
diff --git a/test/test_wheel.py b/test/test_wheel.py
new file mode 100644
index 0000000..87e4880
--- /dev/null
+++ b/test/test_wheel.py
@@ -0,0 +1,47 @@
+import subprocess
+import sys
+from email.parser import BytesParser
+from pathlib import Path
+from zipfile import ZipFile
+
+
+def test_wheel_is_platform_specific(tmp_path: Path) -> None:
+    """Check wheel compatibility tags and the bundled library's location.
+
+    Args:
+        tmp_path: Directory for the built wheel.
+
+    """
+    root = Path(__file__).resolve().parents[1]
+    subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "pip",
+            "wheel",
+            "--no-deps",
+            "--no-build-isolation",
+            "--wheel-dir",
+            str(tmp_path),
+            str(root),
+        ],
+        check=True,
+        timeout=180,
+    )
+    [wheel] = tmp_path.glob("libfaketime-*.whl")
+    _, python_tag, abi_tag, platform_tag = wheel.stem.rsplit("-", 3)
+    assert python_tag == "py3"
+    assert abi_tag == "none"
+    assert platform_tag != "any"
+
+    library_name = (
+        "libfaketime.1.dylib" if sys.platform == "darwin" else "libfaketime.so.1"
+    )
+    with ZipFile(wheel) as archive:
+        [metadata_path] = (
+            name for name in archive.namelist() if name.endswith(".dist-info/WHEEL")
+        )
+        metadata = BytesParser().parsebytes(archive.read(metadata_path))
+        assert metadata["Root-Is-Purelib"] == "false"
+        library = archive.getinfo(f"libfaketime/vendor/libfaketime/src/{library_name}")
+        assert library.file_size > 0