gh-93939: Add script to check extension modules (#94545)

Add script ``Tools/scripts/check_modules.py`` to check and validate builtin
and shared extension modules. The script also handles ``Modules/Setup`` and
will eventually replace ``setup.py``.

Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@protonmail.com>

4 files changed, 504 insertions, 41 deletions

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 14e7f60..ee67a01 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -918,6 +918,9 @@ oldsharedmods: $(SHAREDMODS) pybuilddir.txt
 		fi; \
 	done
 
+checksharedmods: oldsharedmods sharedmods $(PYTHON_FOR_BUILD_DEPS)
+	@$(RUNSHARED) $(PYTHON_FOR_BUILD) $(srcdir)/Tools/scripts/check_extension_modules.py
+
 Modules/Setup.local:
 	@# Create empty Setup.local when file was deleted by user
 	echo "# Edit this file for local setup changes" > $@
@@ -2531,7 +2534,8 @@ update-config:
 Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 
 # Declare targets that aren't real files
-.PHONY: all build_all build_wasm sharedmods check-clean-src oldsharedmods test quicktest
+.PHONY: all build_all build_wasm sharedmods check-clean-src
+.PHONY: oldsharedmods checksharedmods test quicktest
 .PHONY: install altinstall oldsharedinstall bininstall altbininstall
 .PHONY: maninstall libinstall inclinstall libainstall sharedinstall
 .PHONY: frameworkinstall frameworkinstallframework frameworkinstallstructure
diff --git a/Misc/NEWS.d/next/Tools-Demos/2022-07-04-10-02-02.gh-issue-93939.U6sW6H.rst b/Misc/NEWS.d/next/Tools-Demos/2022-07-04-10-02-02.gh-issue-93939.U6sW6H.rst
new file mode 100644
index 0000000..a129d68
--- /dev/null
+++ b/Misc/NEWS.d/next/Tools-Demos/2022-07-04-10-02-02.gh-issue-93939.U6sW6H.rst
@@ -0,0 +1,3 @@
+Add script ``Tools/scripts/check_modules.py`` to check and validate builtin
+and shared extension modules. The script also handles ``Modules/Setup`` and
+will eventually replace ``setup.py``.
diff --git a/Tools/scripts/check_extension_modules.py b/Tools/scripts/check_extension_modules.py
new file mode 100644
index 0000000..b3f43ab
--- /dev/null
+++ b/Tools/scripts/check_extension_modules.py
@@ -0,0 +1,489 @@
+"""Check extension modules
+
+The script checks shared and built-in extension modules. It verifies that the
+modules have been built and that they can be imported successfully. Missing
+modules and failed imports are reported to the user. Shared extension
+files are renamed on failed import.
+
+Module information is parsed from several sources:
+
+- core modules hard-coded in Modules/config.c.in
+- Windows-specific modules that are hard-coded in PC/config.c
+- MODULE_{name}_STATE entries in Makefile (provided through sysconfig)
+- Various makesetup files:
+  - $(srcdir)/Modules/Setup
+  - Modules/Setup.[local|bootstrap|stdlib] files, which are generated
+    from $(srcdir)/Modules/Setup.*.in files
+
+See --help for more information
+"""
+import argparse
+import collections
+import enum
+import logging
+import os
+import pathlib
+import re
+import sys
+import sysconfig
+import warnings
+
+from importlib._bootstrap import _load as bootstrap_load
+from importlib.machinery import BuiltinImporter, ExtensionFileLoader, ModuleSpec
+from importlib.util import spec_from_file_location, spec_from_loader
+from typing import Iterable
+
+SRC_DIR = pathlib.Path(__file__).parent.parent.parent
+
+# core modules, hard-coded in Modules/config.h.in
+CORE_MODULES = {
+    "_ast",
+    "_imp",
+    "_string",
+    "_tokenize",
+    "_warnings",
+    "builtins",
+    "gc",
+    "marshal",
+    "sys",
+}
+
+# Windows-only modules
+WINDOWS_MODULES = {
+    "_msi",
+    "_overlapped",
+    "_testconsole",
+    "_winapi",
+    "msvcrt",
+    "nt",
+    "winreg",
+    "winsound",
+}
+
+
+logger = logging.getLogger(__name__)
+
+parser = argparse.ArgumentParser(
+    prog="check_extension_modules",
+    description=__doc__,
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+)
+
+parser.add_argument(
+    "--verbose",
+    action="store_true",
+    help="Verbose, report builtin, shared, and unavailable modules",
+)
+
+parser.add_argument(
+    "--debug",
+    action="store_true",
+    help="Enable debug logging",
+)
+
+parser.add_argument(
+    "--strict",
+    action=argparse.BooleanOptionalAction,
+    help=(
+        "Strict check, fail when a module is missing or fails to import"
+        "(default: no, unless env var PYTHONSTRICTEXTENSIONBUILD is set)"
+    ),
+    default=bool(os.environ.get("PYTHONSTRICTEXTENSIONBUILD")),
+)
+
+parser.add_argument(
+    "--cross-compiling",
+    action=argparse.BooleanOptionalAction,
+    help=(
+        "Use cross-compiling checks "
+        "(default: no, unless env var _PYTHON_HOST_PLATFORM is set)."
+    ),
+    default="_PYTHON_HOST_PLATFORM" in os.environ,
+)
+
+parser.add_argument(
+    "--list-module-names",
+    action="store_true",
+    help="Print a list of module names to stdout and exit",
+)
+
+
+class ModuleState(enum.Enum):
+    # Makefile state "yes"
+    BUILTIN = "builtin"
+    SHARED = "shared"
+
+    DISABLED = "disabled"
+    MISSING = "missing"
+    NA = "n/a"
+    # disabled by Setup / makesetup rule
+    DISABLED_SETUP = "disabled_setup"
+
+    def __bool__(self):
+        return self.value in {"builtin", "shared"}
+
+
+ModuleInfo = collections.namedtuple("ModuleInfo", "name state")
+
+
+class ModuleChecker:
+    pybuilddir_txt = "pybuilddir.txt"
+
+    setup_files = (
+        SRC_DIR / "Modules/Setup",
+        "Modules/Setup.local",
+        "Modules/Setup.bootstrap",
+        "Modules/Setup.stdlib",
+    )
+
+    def __init__(self, cross_compiling: bool = False, strict: bool = False):
+        self.cross_compiling = cross_compiling
+        self.strict_extensions_build = strict
+        self.ext_suffix = sysconfig.get_config_var("EXT_SUFFIX")
+        self.platform = sysconfig.get_platform()
+        self.builddir = self.get_builddir()
+        self.modules = self.get_modules()
+
+        self.builtin_ok = []
+        self.shared_ok = []
+        self.failed_on_import = []
+        self.missing = []
+        self.disabled_configure = []
+        self.disabled_setup = []
+        self.notavailable = []
+
+    def check(self):
+        for modinfo in self.modules:
+            logger.debug("Checking '%s' (%s)", modinfo.name, self.get_location(modinfo))
+            if modinfo.state == ModuleState.DISABLED:
+                self.disabled_configure.append(modinfo)
+            elif modinfo.state == ModuleState.DISABLED_SETUP:
+                self.disabled_setup.append(modinfo)
+            elif modinfo.state == ModuleState.MISSING:
+                self.missing.append(modinfo)
+            elif modinfo.state == ModuleState.NA:
+                self.notavailable.append(modinfo)
+            else:
+                try:
+                    if self.cross_compiling:
+                        self.check_module_cross(modinfo)
+                    else:
+                        self.check_module_import(modinfo)
+                except (ImportError, FileNotFoundError):
+                    self.rename_module(modinfo)
+                    self.failed_on_import.append(modinfo)
+                else:
+                    if modinfo.state == ModuleState.BUILTIN:
+                        self.builtin_ok.append(modinfo)
+                    else:
+                        assert modinfo.state == ModuleState.SHARED
+                        self.shared_ok.append(modinfo)
+
+    def summary(self, *, verbose: bool = False):
+        longest = max([len(e.name) for e in self.modules], default=0)
+
+        def print_three_column(modinfos: list[ModuleInfo]):
+            names = [modinfo.name for modinfo in modinfos]
+            names.sort(key=str.lower)
+            # guarantee zip() doesn't drop anything
+            while len(names) % 3:
+                names.append("")
+            for l, m, r in zip(names[::3], names[1::3], names[2::3]):
+                print("%-*s   %-*s   %-*s" % (longest, l, longest, m, longest, r))
+
+        if verbose and self.builtin_ok:
+            print("The following *built-in* modules have been successfully built:")
+            print_three_column(self.builtin_ok)
+            print()
+
+        if verbose and self.shared_ok:
+            print("The following *shared* modules have been successfully built:")
+            print_three_column(self.shared_ok)
+            print()
+
+        if self.disabled_configure:
+            print("The following modules are *disabled* in configure script:")
+            print_three_column(self.disabled_configure)
+            print()
+
+        if self.disabled_setup:
+            print("The following modules are *disabled* in Modules/Setup files:")
+            print_three_column(self.disabled_setup)
+            print()
+
+        if verbose and self.notavailable:
+            print(
+                f"The following modules are not available on platform '{self.platform}':"
+            )
+            print_three_column(self.notavailable)
+            print()
+
+        if self.missing:
+            print("The necessary bits to build these optional modules were not found:")
+            print_three_column(self.missing)
+            print("To find the necessary bits, look in configure.ac and config.log.")
+            print()
+
+        if self.failed_on_import:
+            print(
+                "Following modules built successfully "
+                "but were removed because they could not be imported:"
+            )
+            print_three_column(self.failed_on_import)
+            print()
+
+        if any(
+            modinfo.name == "_ssl" for modinfo in self.missing + self.failed_on_import
+        ):
+            print("Could not build the ssl module!")
+            print("Python requires a OpenSSL 1.1.1 or newer")
+            if sysconfig.get_config_var("OPENSSL_LDFLAGS"):
+                print("Custom linker flags may require --with-openssl-rpath=auto")
+            print()
+
+        disabled = len(self.disabled_configure) + len(self.disabled_setup)
+        print(
+            f"Checked {len(self.modules)} modules ("
+            f"{len(self.builtin_ok)} built-in, "
+            f"{len(self.shared_ok)} shared, "
+            f"{len(self.notavailable)} n/a on {self.platform}, "
+            f"{disabled} disabled, "
+            f"{len(self.missing)} missing, "
+            f"{len(self.failed_on_import)} failed on import)"
+        )
+
+    def check_strict_build(self):
+        """Fail if modules are missing and it's a strict build"""
+        if self.strict_extensions_build and (self.failed_on_import or self.missing):
+            raise RuntimeError("Failed to build some stdlib modules")
+
+    def list_module_names(self, *, all: bool = False) -> set:
+        names = {modinfo.name for modinfo in self.modules}
+        if all:
+            names.update(WINDOWS_MODULES)
+        return names
+
+    def get_builddir(self) -> pathlib.Path:
+        try:
+            with open(self.pybuilddir_txt, encoding="utf-8") as f:
+                builddir = f.read()
+        except FileNotFoundError:
+            logger.error("%s must be run from the top build directory", __file__)
+            raise
+        builddir = pathlib.Path(builddir)
+        logger.debug("%s: %s", self.pybuilddir_txt, builddir)
+        return builddir
+
+    def get_modules(self) -> list[ModuleInfo]:
+        """Get module info from sysconfig and Modules/Setup* files"""
+        seen = set()
+        modules = []
+        # parsing order is important, first entry wins
+        for modinfo in self.get_core_modules():
+            modules.append(modinfo)
+            seen.add(modinfo.name)
+        for setup_file in self.setup_files:
+            for modinfo in self.parse_setup_file(setup_file):
+                if modinfo.name not in seen:
+                    modules.append(modinfo)
+                    seen.add(modinfo.name)
+        for modinfo in self.get_sysconfig_modules():
+            if modinfo.name not in seen:
+                modules.append(modinfo)
+                seen.add(modinfo.name)
+        logger.debug("Found %i modules in total", len(modules))
+        modules.sort()
+        return modules
+
+    def get_core_modules(self) -> Iterable[ModuleInfo]:
+        """Get hard-coded core modules"""
+        for name in CORE_MODULES:
+            modinfo = ModuleInfo(name, ModuleState.BUILTIN)
+            logger.debug("Found core module %s", modinfo)
+            yield modinfo
+
+    def get_sysconfig_modules(self) -> Iterable[ModuleInfo]:
+        """Get modules defined in Makefile through sysconfig
+
+        MODBUILT_NAMES: modules in *static* block
+        MODSHARED_NAMES: modules in *shared* block
+        MODDISABLED_NAMES: modules in *disabled* block
+
+        Modules built by setup.py addext() have a MODULE_{modname}_STATE entry,
+        but are not listed in MODSHARED_NAMES.
+
+        Modules built by old-style setup.py add() have neither a  MODULE_{modname}
+        entry nor an entry in MODSHARED_NAMES.
+        """
+        moddisabled = set(sysconfig.get_config_var("MODDISABLED_NAMES").split())
+        if self.cross_compiling:
+            modbuiltin = set(sysconfig.get_config_var("MODBUILT_NAMES").split())
+        else:
+            modbuiltin = set(sys.builtin_module_names)
+
+        for key, value in sysconfig.get_config_vars().items():
+            if not key.startswith("MODULE_") or not key.endswith("_STATE"):
+                continue
+            if value not in {"yes", "disabled", "missing", "n/a"}:
+                raise ValueError(f"Unsupported value '{value}' for {key}")
+
+            modname = key[7:-6].lower()
+            if modname in moddisabled:
+                # Setup "*disabled*" rule
+                state = ModuleState.DISABLED_SETUP
+            elif value in {"disabled", "missing", "n/a"}:
+                state = ModuleState(value)
+            elif modname in modbuiltin:
+                assert value == "yes"
+                state = ModuleState.BUILTIN
+            else:
+                assert value == "yes"
+                state = ModuleState.SHARED
+
+            modinfo = ModuleInfo(modname, state)
+            logger.debug("Found %s in Makefile", modinfo)
+            yield modinfo
+
+    def parse_setup_file(self, setup_file: pathlib.Path) -> Iterable[ModuleInfo]:
+        """Parse a Modules/Setup file"""
+        assign_var = re.compile(r"^\w+=")  # EGG_SPAM=foo
+        # default to static module
+        state = ModuleState.BUILTIN
+        logger.debug("Parsing Setup file %s", setup_file)
+        with open(setup_file, encoding="utf-8") as f:
+            for line in f:
+                line = line.strip()
+                if not line or line.startswith("#") or assign_var.match(line):
+                    continue
+                match line.split():
+                    case ["*shared*"]:
+                        state = ModuleState.SHARED
+                    case ["*static*"]:
+                        state = ModuleState.BUILTIN
+                    case ["*disabled*"]:
+                        state = ModuleState.DISABLED
+                    case ["*noconfig*"]:
+                        state = None
+                    case [*items]:
+                        if state == ModuleState.DISABLED:
+                            # *disabled* can disable multiple modules per line
+                            for item in items:
+                                modinfo = ModuleInfo(item, state)
+                                logger.debug("Found %s in %s", modinfo, setup_file)
+                                yield modinfo
+                        elif state in {ModuleState.SHARED, ModuleState.BUILTIN}:
+                            # *shared* and *static*, first item is the name of the module.
+                            modinfo = ModuleInfo(items[0], state)
+                            logger.debug("Found %s in %s", modinfo, setup_file)
+                            yield modinfo
+
+    def get_spec(self, modinfo: ModuleInfo) -> ModuleSpec:
+        """Get ModuleSpec for builtin or extension module"""
+        if modinfo.state == ModuleState.SHARED:
+            location = os.fspath(self.get_location(modinfo))
+            loader = ExtensionFileLoader(modinfo.name, location)
+            return spec_from_file_location(modinfo.name, location, loader=loader)
+        elif modinfo.state == ModuleState.BUILTIN:
+            return spec_from_loader(modinfo.name, loader=BuiltinImporter)
+        else:
+            raise ValueError(modinfo)
+
+    def get_location(self, modinfo: ModuleInfo) -> pathlib.Path:
+        """Get shared library location in build directory"""
+        if modinfo.state == ModuleState.SHARED:
+            return self.builddir / f"{modinfo.name}{self.ext_suffix}"
+        else:
+            return None
+
+    def _check_file(self, modinfo: ModuleInfo, spec: ModuleSpec):
+        """Check that the module file is present and not empty"""
+        if spec.loader is BuiltinImporter:
+            return
+        try:
+            st = os.stat(spec.origin)
+        except FileNotFoundError:
+            logger.error("%s (%s) is missing", modinfo.name, spec.origin)
+            raise
+        if not st.st_size:
+            raise ImportError(f"{spec.origin} is an empty file")
+
+    def check_module_import(self, modinfo: ModuleInfo):
+        """Attempt to import module and report errors"""
+        spec = self.get_spec(modinfo)
+        self._check_file(modinfo, spec)
+        try:
+            with warnings.catch_warnings():
+                # ignore deprecation warning from deprecated modules
+                warnings.simplefilter("ignore", DeprecationWarning)
+                bootstrap_load(spec)
+        except ImportError as e:
+            logger.error("%s failed to import: %s", modinfo.name, e)
+            raise
+        except Exception as e:
+            logger.exception("Importing extension '%s' failed!", modinfo.name)
+            raise
+
+    def check_module_cross(self, modinfo: ModuleInfo):
+        """Sanity check for cross compiling"""
+        spec = self.get_spec(modinfo)
+        self._check_file(modinfo, spec)
+
+    def rename_module(self, modinfo: ModuleInfo) -> None:
+        """Rename module file"""
+        if modinfo.state == ModuleState.BUILTIN:
+            logger.error("Cannot mark builtin module '%s' as failed!", modinfo.name)
+            return
+
+        failed_name = f"{modinfo.name}_failed{self.ext_suffix}"
+        builddir_path = self.get_location(modinfo)
+        if builddir_path.is_symlink():
+            symlink = builddir_path
+            module_path = builddir_path.resolve().relative_to(os.getcwd())
+            failed_path = module_path.parent / failed_name
+        else:
+            symlink = None
+            module_path = builddir_path
+            failed_path = self.builddir / failed_name
+
+        # remove old failed file
+        failed_path.unlink(missing_ok=True)
+        # remove symlink
+        if symlink is not None:
+            symlink.unlink(missing_ok=True)
+        # rename shared extension file
+        try:
+            module_path.rename(failed_path)
+        except FileNotFoundError:
+            logger.debug("Shared extension file '%s' does not exist.", module_path)
+        else:
+            logger.debug("Rename '%s' -> '%s'", module_path, failed_path)
+
+
+def main():
+    args = parser.parse_args()
+    if args.debug:
+        args.verbose = True
+    logging.basicConfig(
+        level=logging.DEBUG if args.debug else logging.INFO,
+        format="[%(levelname)s] %(message)s",
+    )
+
+    checker = ModuleChecker(
+        cross_compiling=args.cross_compiling,
+        strict=args.strict,
+    )
+    if args.list_module_names:
+        names = checker.list_module_names(all=True)
+        for name in sorted(names):
+            print(name)
+    else:
+        checker.check()
+        checker.summary(verbose=args.verbose)
+        try:
+            checker.check_strict_build()
+        except RuntimeError as e:
+            parser.exit(1, f"\nError: {e}\n")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/Tools/scripts/generate_stdlib_module_names.py b/Tools/scripts/generate_stdlib_module_names.py
index 6f864c3..82f1094 100644
--- a/Tools/scripts/generate_stdlib_module_names.py
+++ b/Tools/scripts/generate_stdlib_module_names.py
@@ -7,10 +7,11 @@ import subprocess
 import sys
 import sysconfig
 
+from check_extension_modules import ModuleChecker
+
 
 SRC_DIR = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
 STDLIB_PATH = os.path.join(SRC_DIR, 'Lib')
-MODULES_SETUP = os.path.join(SRC_DIR, 'Modules', 'Setup')
 SETUP_PY = os.path.join(SRC_DIR, 'setup.py')
 
 IGNORE = {
@@ -41,23 +42,6 @@ IGNORE = {
     'xxsubtype',
 }
 
-# Windows extension modules
-WINDOWS_MODULES = (
-    '_msi',
-    '_overlapped',
-    '_testconsole',
-    '_winapi',
-    'msvcrt',
-    'nt',
-    'winreg',
-    'winsound'
-)
-
-# macOS extension modules
-MACOS_MODULES = (
-    '_scproxy',
-)
-
 # Pure Python modules (Lib/*.py)
 def list_python_modules(names):
     for filename in os.listdir(STDLIB_PATH):
@@ -89,28 +73,11 @@ def list_setup_extensions(names):
     names |= set(extensions)
 
 
-# Built-in and extension modules built by Modules/Setup
+# Built-in and extension modules built by Modules/Setup*
+# includes Windows and macOS extensions.
 def list_modules_setup_extensions(names):
-    assign_var = re.compile("^[A-Z]+=")
-
-    with open(MODULES_SETUP, encoding="utf-8") as modules_fp:
-        for line in modules_fp:
-            # Strip comment
-            line = line.partition("#")[0]
-            line = line.rstrip()
-            if not line:
-                continue
-            if assign_var.match(line):
-                # Ignore "VAR=VALUE"
-                continue
-            if line in ("*disabled*", "*shared*"):
-                continue
-            parts = line.split()
-            if len(parts) < 2:
-                continue
-            # "errno errnomodule.c" => write "errno"
-            name = parts[0]
-            names.add(name)
+    checker = ModuleChecker()
+    names.update(checker.list_module_names(all=True))
 
 
 # List frozen modules of the PyImport_FrozenModules list (Python/frozen.c).
@@ -134,7 +101,7 @@ def list_frozen(names):
 
 
 def list_modules():
-    names = set(sys.builtin_module_names) | set(WINDOWS_MODULES) | set(MACOS_MODULES)
+    names = set(sys.builtin_module_names)
     list_modules_setup_extensions(names)
     list_setup_extensions(names)
     list_packages(names)