ENH: improve RPATH handling

Always strip RPATH pointing to the build directory automatically added by
meson at build time to all artifacts linking to a shared library built as
part of the project. Before this was done only when the project contained a
shared library relocated to .<project-name>.mesonpy.libs.

Add the RPATH entry specified in the meson.build definition via the
install_rpath argument to all artifacts. This automatically remaps the
$ORIGIN anchor to @loader_path on macOS. This requires Meson 1.6.0 or later.

Deduplicate RPATH entries.

Fixes #711.

docs/reference/meson-compatibility.rst

@@ -53,6 +53,10 @@ versions.
    declared via the ``project()`` call in ``meson.build``. This also
    requires ``pyproject-metadata`` version 0.9.0 or later.
 
+   Meson 1.6.0 or later is also required for support for the
+   ``install_rpath`` argument to Meson functions declaring build rules
+   for object files.
+
 Build front-ends by default build packages in an isolated Python
 environment where build dependencies are installed. Most often, unless
 a package or its build dependencies declare explicitly a version

mesonpy/__init__.py

@@ -113,6 +113,7 @@ class InvalidLicenseExpression(Exception):  # type: ignore[no-redef]
 class Entry(typing.NamedTuple):
     dst: pathlib.Path
     src: str
+    rpath: Optional[str] = None
 
 
 def _map_to_wheel(sources: Dict[str, Dict[str, Any]]) -> DefaultDict[str, List[Entry]]:
@@ -161,7 +162,7 @@ def _map_to_wheel(sources: Dict[str, Dict[str, Any]]) -> DefaultDict[str, List[E
                         filedst = dst / relpath
                         wheel_files[path].append(Entry(filedst, filesrc))
             else:
-                wheel_files[path].append(Entry(dst, src))
+                wheel_files[path].append(Entry(dst, src, target.get('install_rpath')))
 
     return wheel_files
 
@@ -420,25 +421,25 @@ def _stable_abi(self) -> Optional[str]:
             return 'abi3'
         return None
 
-    def _install_path(self, wheel_file: mesonpy._wheelfile.WheelFile, origin: Path, destination: pathlib.Path) -> None:
+    def _install_path(self, wheel_file: mesonpy._wheelfile.WheelFile,
+                      origin: Path, destination: pathlib.Path, rpath: Optional[str]) -> None:
         """Add a file to the wheel."""
 
-        if self._has_internal_libs:
-            if _is_native(origin):
-                if sys.platform == 'win32' and not self._allow_windows_shared_libs:
-                    raise NotImplementedError(
-                        'Loading shared libraries bundled in the Python wheel on Windows requires '
-                        'setting the DLL load path or preloading. See the documentation for '
-                        'the "tool.meson-python.allow-windows-internal-shared-libs" option.')
-
-                # When an executable, libray, or Python extension module is
+        if _is_native(origin):
+            libspath = None
+            if self._has_internal_libs:
+                # When an executable, library, or Python extension module is
                 # dynamically linked to a library built as part of the project,
                 # Meson adds a library load path to it pointing to the build
                 # directory, in the form of a relative RPATH entry. meson-python
-                # relocates the shared libraries to the $project.mesonpy.libs
+                # relocates the shared libraries to the ``.<project-name>.mesonpy.libs``
                 # folder. Rewrite the RPATH to point to that folder instead.
                 libspath = os.path.relpath(self._libs_dir, destination.parent)
-                mesonpy._rpath.fix_rpath(origin, libspath)
+
+            # Adjust RPATH: remove build RPATH added by meson, add an RPATH
+            # entries as per above, and add any ``install_rpath`` specified in
+            # meson.build
+            mesonpy._rpath.fix_rpath(origin, rpath, libspath)
 
         try:
             wheel_file.write(origin, destination.as_posix())
@@ -467,6 +468,13 @@ def _wheel_write_metadata(self, whl: mesonpy._wheelfile.WheelFile) -> None:
                 whl.write(f, f'{self._distinfo_dir}/licenses/{pathlib.Path(f).as_posix()}')
 
     def build(self, directory: Path) -> pathlib.Path:
+
+        if sys.platform == 'win32' and self._has_internal_libs and not self._allow_windows_shared_libs:
+            raise ConfigError(
+                'Loading shared libraries bundled in the Python wheel on Windows requires '
+                'setting the DLL load path or preloading. See the documentation for '
+                'the "tool.meson-python.allow-windows-internal-shared-libs" option.')
+
         wheel_file = pathlib.Path(directory, f'{self.name}.whl')
         with mesonpy._wheelfile.WheelFile(wheel_file, 'w') as whl:
             self._wheel_write_metadata(whl)
@@ -476,7 +484,7 @@ def build(self, directory: Path) -> pathlib.Path:
                 root = 'purelib' if self._pure else 'platlib'
 
                 for path, entries in self._manifest.items():
-                    for dst, src in entries:
+                    for dst, src, rpath in entries:
                         counter.update(src)
 
                         if path == root:
@@ -487,7 +495,7 @@ def build(self, directory: Path) -> pathlib.Path:
                         else:
                             dst = pathlib.Path(self._data_dir, path, dst)
 
-                        self._install_path(whl, src, dst)
+                        self._install_path(whl, src, dst, rpath)
 
         return wheel_file
 

mesonpy/_rpath.py

@@ -11,19 +11,81 @@
 
 
 if typing.TYPE_CHECKING:
-    from typing import List
+    from typing import List, Optional, TypeVar
 
     from mesonpy._compat import Iterable, Path
 
+    T = TypeVar('T')
 
-if sys.platform == 'win32' or sys.platform == 'cygwin':
 
-    def fix_rpath(filepath: Path, libs_relative_path: str) -> None:
-        pass
+def unique(values: List[T]) -> List[T]:
+    r = []
+    for value in values:
+        if value not in r:
+            r.append(value)
+    return r
 
-elif sys.platform == 'darwin':
 
+class _Windows:
+
+    @staticmethod
     def _get_rpath(filepath: Path) -> List[str]:
+        return []
+
+    @classmethod
+    def fix_rpath(cls, filepath: Path, install_rpath: Optional[str], libs_rpath: Optional[str]) -> None:
+        pass
+
+
+class RPATH:
+    origin = '$ORIGIN'
+
+    @staticmethod
+    def get_rpath(filepath: Path) -> List[str]:
+        raise NotImplementedError
+
+    @staticmethod
+    def set_rpath(filepath: Path, old: List[str], rpath: List[str]) -> None:
+        raise NotImplementedError
+
+    @classmethod
+    def fix_rpath(cls, filepath: Path, install_rpath: Optional[str], libs_rpath: Optional[str]) -> None:
+        old_rpath = cls.get_rpath(filepath)
+        new_rpath = []
+        if libs_rpath is not None:
+            if libs_rpath == '.':
+                libs_rpath = ''
+            for path in old_rpath:
+                if path.split('/', 1)[0] == cls.origin:
+                    # Any RPATH entry relative to ``$ORIGIN`` is interpreted as
+                    # pointing to a location in the build directory added by
+                    # Meson. These need to be removed. Their presence indicates
+                    # that the executable, shared library, or Python module
+                    # depends on libraries build as part of the package. These
+                    # entries are thus replaced with entries pointing to the
+                    # ``.<package-name>.mesonpy.libs`` folder where meson-python
+                    # relocates shared libraries distributed with the package.
+                    # The package may however explicitly install these in a
+                    # different location, thus this is not a perfect heuristic
+                    # and may add not required RPATH entries. These are however
+                    # harmless.
+                    path = f'{cls.origin}/{libs_rpath}'
+                # Any other RPATH entry is preserved.
+                new_rpath.append(path)
+        if install_rpath:
+            # Add the RPATH entry spcified with the ``install_rpath`` argument.
+            new_rpath.append(install_rpath)
+        # Make the RPATH entries unique.
+        new_rpath = unique(new_rpath)
+        if new_rpath != old_rpath:
+            cls.set_rpath(filepath, old_rpath, new_rpath)
+
+
+class _MacOS(RPATH):
+    origin = '@loader_path'
+
+    @staticmethod
+    def get_rpath(filepath: Path) -> List[str]:
         rpath = []
         r = subprocess.run(['otool', '-l', os.fspath(filepath)], capture_output=True, text=True)
         rpath_tag = False
@@ -35,17 +97,31 @@ def _get_rpath(filepath: Path) -> List[str]:
                 rpath_tag = False
         return rpath
 
-    def _replace_rpath(filepath: Path, old: str, new: str) -> None:
-        subprocess.run(['install_name_tool', '-rpath', old, new, os.fspath(filepath)], check=True)
-
-    def fix_rpath(filepath: Path, libs_relative_path: str) -> None:
-        for path in _get_rpath(filepath):
-            if path.startswith('@loader_path/'):
-                _replace_rpath(filepath, path, '@loader_path/' + libs_relative_path)
-
-elif sys.platform == 'sunos5':
-
-    def _get_rpath(filepath: Path) -> List[str]:
+    @staticmethod
+    def set_rpath(filepath: Path, old: List[str], rpath: List[str]) -> None:
+        args: List[str] = []
+        for path in rpath:
+            if path not in old:
+                args += ['-add_rpath', path]
+        for path in old:
+            if path not in rpath:
+                args += ['-delete_rpath', path]
+        subprocess.run(['install_name_tool', *args, os.fspath(filepath)], check=True)
+
+    @classmethod
+    def fix_rpath(cls, filepath: Path, install_rpath: Optional[str], libs_rpath: Optional[str]) -> None:
+        if install_rpath is not None:
+            root, sep, stem = install_rpath.partition('/')
+            if root == '$ORIGIN':
+                install_rpath = f'{cls.origin}{sep}{stem}'
+                # warnings.warn('...')
+        super().fix_rpath(filepath, install_rpath, libs_rpath)
+
+
+class _SunOS(RPATH):
+
+    @staticmethod
+    def get_rpath(filepath: Path) -> List[str]:
         rpath = []
         r = subprocess.run(['/usr/bin/elfedit', '-r', '-e', 'dyn:rpath', os.fspath(filepath)],
             capture_output=True, check=True, text=True)
@@ -56,35 +132,31 @@ def _get_rpath(filepath: Path) -> List[str]:
                         rpath.append(path)
         return rpath
 
-    def _set_rpath(filepath: Path, rpath: Iterable[str]) -> None:
+    @staticmethod
+    def set_rpath(filepath: Path, old: Iterable[str], rpath: Iterable[str]) -> None:
         subprocess.run(['/usr/bin/elfedit', '-e', 'dyn:rpath ' + ':'.join(rpath), os.fspath(filepath)], check=True)
 
-    def fix_rpath(filepath: Path, libs_relative_path: str) -> None:
-        old_rpath = _get_rpath(filepath)
-        new_rpath = []
-        for path in old_rpath:
-            if path.startswith('$ORIGIN/'):
-                path = '$ORIGIN/' + libs_relative_path
-            new_rpath.append(path)
-        if new_rpath != old_rpath:
-            _set_rpath(filepath, new_rpath)
 
-else:
-    # Assume that any other platform uses ELF binaries.
+class _ELF(RPATH):
 
-    def _get_rpath(filepath: Path) -> List[str]:
+    @staticmethod
+    def get_rpath(filepath: Path) -> List[str]:
         r = subprocess.run(['patchelf', '--print-rpath', os.fspath(filepath)], capture_output=True, text=True)
         return r.stdout.strip().split(':')
 
-    def _set_rpath(filepath: Path, rpath: Iterable[str]) -> None:
+    @staticmethod
+    def set_rpath(filepath: Path, old: Iterable[str], rpath: Iterable[str]) -> None:
         subprocess.run(['patchelf','--set-rpath', ':'.join(rpath), os.fspath(filepath)], check=True)
 
-    def fix_rpath(filepath: Path, libs_relative_path: str) -> None:
-        old_rpath = _get_rpath(filepath)
-        new_rpath = []
-        for path in old_rpath:
-            if path.startswith('$ORIGIN/'):
-                path = '$ORIGIN/' + libs_relative_path
-            new_rpath.append(path)
-        if new_rpath != old_rpath:
-            _set_rpath(filepath, new_rpath)
+
+if sys.platform == 'win32' or sys.platform == 'cygwin':
+    _cls = _Windows
+elif sys.platform == 'darwin':
+    _cls = _MacOS
+elif sys.platform == 'sunos5':
+    _cls = _SunOS
+else:
+    _cls = _ELF
+
+_get_rpath = _cls.get_rpath
+fix_rpath = _cls.fix_rpath