Suppress macholib header parse error

Macholib raises ValueError when failing to parse files which can be used
to detect if the file is a Mach-O object.
It is also raised on Mach-O objects it doesn't know how to handle.

Checking for this error means `_is_macho_file` is redundant.

Add min version tests for various file types.
These tests clarify that static libraries don't have min version info.

Changelog.md

@@ -34,6 +34,8 @@ rules on making a good Changelog.
 - `delocate-merge` now supports libraries with missing or unusual extensions.
   [#228](https://github.com/matthew-brett/delocate/issues/228)
 - Now supports library files ending in parentheses.
+- Fixed `Unknown Mach-O header` error when encountering a fat static library.
+  [#229](https://github.com/matthew-brett/delocate/issues/229)
 
 ### Removed
 

delocate/delocating.py

@@ -40,7 +40,6 @@
 from .pkginfo import read_pkg_info, write_pkg_info
 from .tmpdirs import TemporaryDirectory
 from .tools import (
-    _is_macho_file,
     _remove_absolute_rpaths,
     dir2zip,
     find_package_dirs,
@@ -584,12 +583,14 @@ def _make_install_name_ids_unique(
         validate_signature(lib)
 
 
-def _get_macos_min_version(dylib_path: Path) -> Iterator[tuple[str, Version]]:
+def _get_macos_min_version(
+    dylib_path: str | os.PathLike[str],
+) -> Iterator[tuple[str, Version]]:
     """Get the minimum macOS version from a dylib file.
 
     Parameters
     ----------
-    dylib_path : Path
+    dylib_path : str or PathLike
         The path to the dylib file.
 
     Yields
@@ -599,9 +600,16 @@ def _get_macos_min_version(dylib_path: Path) -> Iterator[tuple[str, Version]]:
     Version
         The minimum macOS version.
     """
-    if not _is_macho_file(dylib_path):
-        return
-    for header in MachO(dylib_path).headers:
+    try:
+        macho = MachO(dylib_path)
+    except ValueError as exc:
+        if str(exc.args[0]).startswith(
+            ("Unknown fat header magic", "Unknown Mach-O header")
+        ):
+            return  # Not a recognised Mach-O object file
+        raise  # pragma: no cover  # Unexpected error
+
+    for header in macho.headers:
         for cmd in header.commands:
             if cmd[0].cmd == LC_BUILD_VERSION:
                 version = cmd[1].minos
@@ -798,6 +806,8 @@ def _calculate_minimum_wheel_name(
     all_library_versions: dict[str, dict[Version, list[Path]]] = {}
 
     for lib in wheel_dir.glob("**/*"):
+        if lib.is_dir():
+            continue
         for arch, version in _get_macos_min_version(lib):
             all_library_versions.setdefault(arch.lower(), {}).setdefault(
                 version, []

delocate/tests/test_delocating.py

@@ -1,5 +1,7 @@
 """Tests for relocating libraries."""
 
+from __future__ import annotations
+
 import os
 import shutil
 import subprocess
@@ -8,6 +10,7 @@
 from collections.abc import Iterable
 from os.path import basename, dirname, realpath, relpath, splitext
 from os.path import join as pjoin
+from pathlib import Path
 from typing import Any, Callable
 
 import pytest
@@ -16,6 +19,7 @@
 
 from ..delocating import (
     _get_archs_and_version_from_wheel_name,
+    _get_macos_min_version,
     bads_report,
     check_archs,
     copy_recurse,
@@ -33,7 +37,18 @@
 from ..tools import get_install_names, set_install_name
 from .env_tools import TempDirWithoutEnvVars
 from .pytest_tools import assert_equal, assert_raises
-from .test_install_names import EXT_LIBS, LIBA, LIBB, LIBC, TEST_LIB, _copy_libs
+from .test_install_names import (
+    A_OBJECT,
+    DATA_PATH,
+    EXT_LIBS,
+    ICO_FILE,
+    LIBA,
+    LIBA_STATIC,
+    LIBB,
+    LIBC,
+    TEST_LIB,
+    _copy_libs,
+)
 from .test_tools import (
     ARCH_32,
     ARCH_64,
@@ -747,3 +762,28 @@ def test_get_archs_and_version_from_wheel_name() -> None:
         _get_archs_and_version_from_wheel_name(
             "foo-1.0-py310-abi3-manylinux1.whl"
         )
+
+
+@pytest.mark.parametrize(
+    "file,expected_min_version",
+    [
+        # Dylib files
+        (LIBBOTH, {"ARM64": Version("11.0"), "x86_64": Version("10.9")}),
+        (LIBA, {"x86_64": Version("10.9")}),
+        # Shared objects
+        (
+            Path(DATA_PATH, "np-1.6.0_intel_lib__compiled_base.so"),
+            {"i386": Version("10.6"), "x86_64": Version("10.6")},
+        ),
+        # Object file
+        (A_OBJECT, {"x86_64": Version("10.9")}),
+        # Static file
+        (LIBA_STATIC, {}),
+        # Non library
+        (ICO_FILE, {}),
+    ],
+)
+def test_get_macos_min_version(
+    file: str | Path, expected_min_version: dict[str, Version]
+) -> None:
+    assert dict(_get_macos_min_version(file)) == expected_min_version