GR-26502: add missing _ZipImportResourceReader to the zipimport builtin

Author: cosminbasca

graalpython/lib-graalpython/zipimport.py

@@ -43,3 +43,93 @@
 
 zipimporter.create_module = lambda self, spec: None
 zipimporter.exec_module = lambda self, module: exec(self.get_code(module.__name__), module.__dict__)
+
+
+class _ZipImportResourceReader:
+    """Private class used to support ZipImport.get_resource_reader().
+
+    This class is allowed to reference all the innards and private parts of
+    the zipimporter.
+    """
+    _registered = False
+
+    def __init__(self, zipimporter, fullname):
+        self.zipimporter = zipimporter
+        self.fullname = fullname
+
+    def open_resource(self, resource):
+        fullname_as_path = self.fullname.replace('.', '/')
+        path = f'{fullname_as_path}/{resource}'
+        from io import BytesIO
+        try:
+            return BytesIO(self.zipimporter.get_data(path))
+        except OSError:
+            raise FileNotFoundError(path)
+
+    def resource_path(self, resource):
+        # All resources are in the zip file, so there is no path to the file.
+        # Raising FileNotFoundError tells the higher level API to extract the
+        # binary data and create a temporary file.
+        raise FileNotFoundError
+
+    def is_resource(self, name):
+        # Maybe we could do better, but if we can get the data, it's a
+        # resource.  Otherwise it isn't.
+        fullname_as_path = self.fullname.replace('.', '/')
+        path = f'{fullname_as_path}/{name}'
+        try:
+            self.zipimporter.get_data(path)
+        except OSError:
+            return False
+        return True
+
+    def contents(self):
+        # This is a bit convoluted, because fullname will be a module path,
+        # but _files is a list of file names relative to the top of the
+        # archive's namespace.  We want to compare file paths to find all the
+        # names of things inside the module represented by fullname.  So we
+        # turn the module path of fullname into a file path relative to the
+        # top of the archive, and then we iterate through _files looking for
+        # names inside that "directory".
+        from pathlib import Path
+        fullname_path = Path(self.zipimporter.get_filename(self.fullname))
+        relative_path = fullname_path.relative_to(self.zipimporter.archive)
+        # Don't forget that fullname names a package, so its path will include
+        # __init__.py, which we want to ignore.
+        assert relative_path.name == '__init__.py'
+        package_path = relative_path.parent
+        subdirs_seen = set()
+        for filename in self.zipimporter._files:
+            try:
+                relative = Path(filename).relative_to(package_path)
+            except ValueError:
+                continue
+            # If the path of the file (which is relative to the top of the zip
+            # namespace), relative to the package given when the resource
+            # reader was created, has a parent, then it's a name in a
+            # subdirectory and thus we skip it.
+            parent_name = relative.parent.name
+            if len(parent_name) == 0:
+                yield relative.name
+            elif parent_name not in subdirs_seen:
+                subdirs_seen.add(parent_name)
+                yield parent_name
+
+def _get_resource_reader(self, fullname):
+    """Return the ResourceReader for a package in a zip file.
+
+    If 'fullname' is a package within the zip file, return the
+    'ResourceReader' object for the package.  Otherwise return None.
+    """
+    try:
+        if not self.is_package(fullname):
+            return None
+    except ZipImportError:
+        return None
+    if not _ZipImportResourceReader._registered:
+        from importlib.abc import ResourceReader
+        ResourceReader.register(_ZipImportResourceReader)
+        _ZipImportResourceReader._registered = True
+    return _ZipImportResourceReader(self, fullname)
+
+zipimporter.get_resource_reader = _get_resource_reader