Allow zipfile to be imported on wasm

Lib/_dummy_os.py

@@ -0,0 +1,61 @@
+"""
+A shim of the os module containing only simple path-related utilities
+"""
+
+try:
+    from os import *
+except ImportError:
+    import abc
+
+    # this will throw an appropriate error if os isn't available and a module
+    # tries to use an os function. If os has become available, then this will
+    # just work.
+    def __getattr__(name):
+        import os
+        return getattr(os, name)
+
+
+    sep = '/'
+
+
+    def fspath(path):
+        """Return the path representation of a path-like object.
+
+        If str or bytes is passed in, it is returned unchanged. Otherwise the
+        os.PathLike interface is used to get the path representation. If the
+        path representation is not str or bytes, TypeError is raised. If the
+        provided path is not str, bytes, or os.PathLike, TypeError is raised.
+        """
+        if isinstance(path, (str, bytes)):
+            return path
+
+        # Work from the object's type to match method resolution of other magic
+        # methods.
+        path_type = type(path)
+        try:
+            path_repr = path_type.__fspath__(path)
+        except AttributeError:
+            if hasattr(path_type, '__fspath__'):
+                raise
+            else:
+                raise TypeError("expected str, bytes or os.PathLike object, "
+                                "not " + path_type.__name__)
+        if isinstance(path_repr, (str, bytes)):
+            return path_repr
+        else:
+            raise TypeError("expected {}.__fspath__() to return str or bytes, "
+                            "not {}".format(path_type.__name__,
+                                            type(path_repr).__name__))
+
+    class PathLike(abc.ABC):
+
+        """Abstract base class for implementing the file system path protocol."""
+
+        @abc.abstractmethod
+        def __fspath__(self):
+            """Return the file system path representation of the object."""
+            raise NotImplementedError
+
+        @classmethod
+        def __subclasshook__(cls, subclass):
+            return hasattr(subclass, '__fspath__')

Lib/genericpath.py

@@ -3,7 +3,10 @@ Path operations common to more than one OS
 Do not use directly.  The OS specific modules import the appropriate
 functions from this module themselves.
 """
-import os
+try:
+    import os
+except ImportError:
+    import _dummy_os as os
 import stat
 
 __all__ = ['commonprefix', 'exists', 'getatime', 'getctime', 'getmtime',

Lib/io.py

@@ -52,12 +52,17 @@ import _io
 import abc
 
 from _io import (DEFAULT_BUFFER_SIZE, BlockingIOError, UnsupportedOperation,
-                 open, open_code, FileIO, BytesIO, StringIO, BufferedReader,
+                 open, open_code, BytesIO, StringIO, BufferedReader,
                  BufferedWriter, BufferedRWPair, BufferedRandom,
                  # XXX RUSTPYTHON TODO: IncrementalNewlineDecoder
                  # IncrementalNewlineDecoder, TextIOWrapper)
                  TextIOWrapper)
 
+try:
+    from _io import FileIO
+except ImportError:
+    pass
+
 OpenWrapper = _io.open # for compatibility with _pyio
 
 # Pretend this exception was created here.

Lib/posixpath.py

@@ -22,7 +22,10 @@ defpath = '/bin:/usr/bin'
 altsep = None
 devnull = '/dev/null'
 
-import os
+try:
+    import os
+except ImportError:
+    import _dummy_os as os
 import sys
 import stat
 import genericpath

Lib/zipfile.py

@@ -8,13 +8,22 @@ import functools
 import importlib.util
 import io
 import itertools
-import os
+try:
+    import os
+except ImportError:
+    import _dummy_os as os
 import posixpath
-import shutil
+try:
+    import shutil
+except ImportError:
+    pass
 import stat
 import struct
 import sys
-import threading
+try:
+    import threading
+except ImportError:
+    import _dummy_thread as threading
 import time
 import contextlib
 from collections import OrderedDict