PEP 302 + zipimport:

- new import hooks in import.c, exposed in the sys module
- new module called 'zipimport'
- various changes to allow bootstrapping from zip files

I hope I didn't break the Windows build (or anything else for that
matter), but then again, it's been sitting on sf long enough...

Regarding the latest discussions on python-dev: zipimport sets
pkg.__path__ as specified in PEP 273, and likewise, sys.path item such as
/path/to/Archive.zip/subdir/ are supported again.

Include/pythonrun.h

@@ -99,6 +99,7 @@ PyAPI_FUNC(PyObject *) _PyBuiltin_Init(void);
 PyAPI_FUNC(PyObject *) _PySys_Init(void);
 PyAPI_FUNC(void) _PyImport_Init(void);
 PyAPI_FUNC(void) _PyExc_Init(void);
+PyAPI_FUNC(void) _PyImportHooks_Init(void);
 
 /* Various internal finalizers */
 PyAPI_FUNC(void) _PyExc_Fini(void);

Lib/site.py

@@ -73,16 +73,11 @@ del m
 # only absolute pathnames, even if we're running from the build directory.
 L = []
 _dirs_in_sys_path = {}
+dir = dircase = None  # sys.path may be empty at this point
 for dir in sys.path:
-    # Filter out paths that don't exist, but leave in the empty string
+    # Filter out duplicate paths (on case-insensitive file systems also
-    # since it's a special case. We also need to special-case the Mac,
+    # if they only differ in case); turn relative paths into absolute
-    # as file names are allowed on sys.path there.
+    # paths.
-    if sys.platform != 'mac':
-        if dir and not os.path.isdir(dir):
-            continue
-    else:
-        if dir and not os.path.exists(dir):
-            continue
     dir, dircase = makepath(dir)
     if not dircase in _dirs_in_sys_path:
         L.append(dir)

Lib/test/test_importhooks.py

@@ -0,0 +1,204 @@
+import sys
+import imp
+import os
+import unittest
+from test import test_support
+
+
+test_src = """\
+def get_name():
+    return __name__
+def get_file():
+    return __file__
+"""
+
+test_co = compile(test_src, "<???>", "exec")
+test_path = "!!!_test_!!!"
+
+
+class ImportTracker:
+    """Importer that only tracks attempted imports."""
+    def __init__(self):
+        self.imports = []
+    def find_module(self, fullname, path=None):
+        self.imports.append(fullname)
+        return None
+
+
+class TestImporter:
+
+    modules = {
+        "hooktestmodule": (False, test_co),
+        "hooktestpackage": (True, test_co),
+        "hooktestpackage.sub": (True, test_co),
+        "hooktestpackage.sub.subber": (False, test_co),
+    }
+
+    def __init__(self, path=test_path):
+        if path != test_path:
+            # if out class is on sys.path_hooks, we must raise
+            # ImportError for any path item that we can't handle.
+            raise ImportError
+        self.path = path
+
+    def _get__path__(self):
+        raise NotImplementedError
+
+    def find_module(self, fullname, path=None):
+        if fullname in self.modules:
+            return self
+        else:
+            return None
+
+    def load_module(self, fullname):
+        ispkg, code = self.modules[fullname]
+        mod = imp.new_module(fullname)
+        sys.modules[fullname] = mod
+        mod.__file__ = "<%s>" % self.__class__.__name__
+        mod.__loader__ = self
+        if ispkg:
+            mod.__path__ = self._get__path__()
+        exec code in mod.__dict__
+        return mod
+
+
+class MetaImporter(TestImporter):
+    def _get__path__(self):
+        return []
+
+class PathImporter(TestImporter):
+    def _get__path__(self):
+        return [self.path]
+
+
+class ImportBlocker:
+    """Place an ImportBlocker instance on sys.meta_path and you
+    can be sure the modules you specified can't be imported, even
+    if it's a builtin."""
+    def __init__(self, *namestoblock):
+        self.namestoblock = dict.fromkeys(namestoblock)
+    def find_module(self, fullname, path=None):
+        if fullname in self.namestoblock:
+            return self
+        return None
+    def load_module(self, fullname):
+        raise ImportError, "I dare you"
+
+
+class ImpWrapper:
+
+    def __init__(self, path=None):
+        if path is not None and not os.path.isdir(path):
+            raise ImportError
+        self.path = path
+
+    def find_module(self, fullname, path=None):
+        subname = fullname.split(".")[-1]
+        if subname != fullname and self.path is None:
+            return None
+        if self.path is None:
+            path = None
+        else:
+            path = [self.path]
+        try:
+            file, filename, stuff = imp.find_module(subname, path)
+        except ImportError:
+            return None
+        return ImpLoader(file, filename, stuff)
+
+
+class ImpLoader:
+
+    def __init__(self, file, filename, stuff):
+        self.file = file
+        self.filename = filename
+        self.stuff = stuff
+
+    def load_module(self, fullname):
+        mod = imp.load_module(fullname, self.file, self.filename, self.stuff)
+        if self.file:
+            self.file.close()
+        mod.__loader__ = self  # for introspection
+        return mod
+
+
+class ImportHooksBaseTestCase(unittest.TestCase):
+
+    def setUp(self):
+        self.path = sys.path[:]
+        self.meta_path = sys.meta_path[:]
+        self.path_hooks = sys.path_hooks[:]
+        sys.path_importer_cache.clear()
+        self.tracker = ImportTracker()
+        sys.meta_path.insert(0, self.tracker)
+
+    def tearDown(self):
+        sys.path[:] = self.path
+        sys.meta_path[:] = self.meta_path
+        sys.path_hooks[:] = self.path_hooks
+        sys.path_importer_cache.clear()
+        for fullname in self.tracker.imports:
+            if fullname in sys.modules:
+                del sys.modules[fullname]
+
+
+class ImportHooksTestCase(ImportHooksBaseTestCase):
+
+    def doTestImports(self, importer=None):
+        import hooktestmodule
+        import hooktestpackage
+        import hooktestpackage.sub
+        import hooktestpackage.sub.subber
+        self.assertEqual(hooktestmodule.get_name(),
+                         "hooktestmodule")
+        self.assertEqual(hooktestpackage.get_name(),
+                         "hooktestpackage")
+        self.assertEqual(hooktestpackage.sub.get_name(),
+                         "hooktestpackage.sub")
+        self.assertEqual(hooktestpackage.sub.subber.get_name(),
+                         "hooktestpackage.sub.subber")
+        if importer:
+            self.assertEqual(hooktestmodule.__loader__, importer)
+            self.assertEqual(hooktestpackage.__loader__, importer)
+            self.assertEqual(hooktestpackage.sub.__loader__, importer)
+            self.assertEqual(hooktestpackage.sub.subber.__loader__, importer)
+
+    def testMetaPath(self):
+        i = MetaImporter()
+        sys.meta_path.append(i)
+        self.doTestImports(i)
+
+    def testPathHook(self):
+        sys.path_hooks.append(PathImporter)
+        sys.path.append(test_path)
+        self.doTestImports()
+
+    def testBlocker(self):
+        mname = "exceptions"  # an arbitrary harmless builtin module
+        if mname in sys.modules:
+            del sys.modules[mname]
+        sys.meta_path.append(ImportBlocker(mname))
+        try:
+            __import__(mname)
+        except ImportError:
+            pass
+        else:
+            self.fail("'%s' was not supposed to be importable" % mname)
+
+    def testImpWrapper(self):
+        i = ImpWrapper()
+        sys.meta_path.append(i)
+        sys.path_hooks.append(ImpWrapper)
+        mnames = ("colorsys", "urlparse", "distutils.core", "compiler.misc")
+        for mname in mnames:
+            parent = mname.split(".")[0]
+            for n in sys.modules.keys():
+                if n.startswith(parent):
+                    del sys.modules[n]
+        for mname in mnames:
+            m = __import__(mname, globals(), locals(), ["__dummy__"])
+            m.__loader__  # to make sure we actually handled the import
+
+
+if __name__ == "__main__":
+    test_support.run_unittest(ImportHooksTestCase)

Lib/test/test_zipimport.py

@@ -0,0 +1,180 @@
+import sys
+import os
+import marshal
+import imp
+import struct
+import time
+
+import zlib # implied prerequisite
+from zipfile import ZipFile, ZipInfo, ZIP_STORED, ZIP_DEFLATED
+from test import test_support
+from test.test_importhooks import ImportHooksBaseTestCase, test_src, test_co
+
+import zipimport
+
+
+def make_pyc(co, mtime):
+    data = marshal.dumps(co)
+    pyc = imp.get_magic() + struct.pack("<i", mtime) + data
+    return pyc
+
+NOW = time.time()
+test_pyc = make_pyc(test_co, NOW)
+
+
+if __debug__:
+    pyc_ext = ".pyc"
+else:
+    pyc_ext = ".pyo"
+
+
+TESTMOD = "ziptestmodule"
+TESTPACK = "ziptestpackage"
+TEMP_ZIP = "junk95142.zip"
+
+
+class UncompressedZipImportTestCase(ImportHooksBaseTestCase):
+
+    compression = ZIP_STORED
+
+    def setUp(self):
+        # We're reusing the zip archive path, so we must clear the
+        # cached directory info.
+        zipimport._zip_directory_cache.clear()
+        ImportHooksBaseTestCase.setUp(self)
+
+    def doTest(self, expected_ext, files, *modules):
+        z = ZipFile(TEMP_ZIP, "w")
+        try:
+            for name, (mtime, data) in files.items():
+                zinfo = ZipInfo(name, time.localtime(mtime))
+                zinfo.compress_type = self.compression
+                z.writestr(zinfo, data)
+            z.close()
+            sys.path.insert(0, TEMP_ZIP)
+
+            mod = __import__(".".join(modules), globals(), locals(),
+                             ["__dummy__"])
+            file = mod.get_file()
+            self.assertEquals(file, os.path.join(TEMP_ZIP,
+                              os.sep.join(modules) + expected_ext))
+        finally:
+            z.close()
+            os.remove(TEMP_ZIP)
+
+    def testAFakeZlib(self):
+        #
+        # This could cause a stack overflow before: importing zlib.py
+        # from a compressed archive would cause zlib to be imported
+        # which would find zlib.py in the archive, which would... etc.
+        #
+        # This test *must* be executed first: it must be the first one
+        # to trigger zipimport to import zlib (zipimport caches the
+        # zlib.decompress function object, after which the problem being
+        # tested here wouldn't be a problem anymore...
+        # (Hence the 'A' in the test method name: to make it the first
+        # item in a list sorted by name, like unittest.makeSuite() does.)
+        #
+        if "zlib" in sys.modules:
+            del sys.modules["zlib"]
+        files = {"zlib.py": (NOW, test_src)}
+        try:
+            self.doTest(".py", files, "zlib")
+        except ImportError:
+            if self.compression != ZIP_DEFLATED:
+                self.fail("expected test to not raise ImportError")
+        else:
+            if self.compression != ZIP_STORED:
+                self.fail("expected test to raise ImportError")
+
+    def testPy(self):
+        files = {TESTMOD + ".py": (NOW, test_src)}
+        self.doTest(".py", files, TESTMOD)
+
+    def testPyc(self):
+        files = {TESTMOD + pyc_ext: (NOW, test_pyc)}
+        self.doTest(pyc_ext, files, TESTMOD)
+
+    def testBoth(self):
+        files = {TESTMOD + ".py": (NOW, test_src),
+                 TESTMOD + pyc_ext: (NOW, test_pyc)}
+        self.doTest(pyc_ext, files, TESTMOD)
+
+    def testBadMagic(self):
+        # make pyc magic word invalid, forcing loading from .py
+        m0 = ord(test_pyc[0])
+        m0 ^= 0x04  # flip an arbitrary bit
+        badmagic_pyc = chr(m0) + test_pyc[1:]
+        files = {TESTMOD + ".py": (NOW, test_src),
+                 TESTMOD + pyc_ext: (NOW, badmagic_pyc)}
+        self.doTest(".py", files, TESTMOD)
+
+    def testBadMagic2(self):
+        # make pyc magic word invalid, causing an ImportError
+        m0 = ord(test_pyc[0])
+        m0 ^= 0x04  # flip an arbitrary bit
+        badmagic_pyc = chr(m0) + test_pyc[1:]
+        files = {TESTMOD + pyc_ext: (NOW, badmagic_pyc)}
+        try:
+            self.doTest(".py", files, TESTMOD)
+        except ImportError:
+            pass
+        else:
+            self.fail("expected ImportError; import from bad pyc")
+
+    def testBadMTime(self):
+        t3 = ord(test_pyc[7])
+        t3 ^= 0x02  # flip the second bit -- not the first as that one
+                    # isn't stored in the .py's mtime in the zip archive.
+        badtime_pyc = test_pyc[:7] + chr(t3) + test_pyc[8:]
+        files = {TESTMOD + ".py": (NOW, test_src),
+                 TESTMOD + pyc_ext: (NOW, badtime_pyc)}
+        self.doTest(".py", files, TESTMOD)
+
+    def testPackage(self):
+        packdir = TESTPACK + os.sep
+        files = {packdir + "__init__" + pyc_ext: (NOW, test_pyc),
+                 packdir + TESTMOD + pyc_ext: (NOW, test_pyc)}
+        self.doTest(pyc_ext, files, TESTPACK, TESTMOD)
+
+    def testDeepPackage(self):
+        packdir = TESTPACK + os.sep
+        packdir2 = packdir + packdir
+        files = {packdir + "__init__" + pyc_ext: (NOW, test_pyc),
+                 packdir2 + "__init__" + pyc_ext: (NOW, test_pyc),
+                 packdir2 + TESTMOD + pyc_ext: (NOW, test_pyc)}
+        self.doTest(pyc_ext, files, TESTPACK, TESTPACK, TESTMOD)
+
+    def testGetData(self):
+        z = ZipFile(TEMP_ZIP, "w")
+        z.compression = self.compression
+        try:
+            name = "testdata.dat"
+            data = "".join([chr(x) for x in range(256)]) * 500
+            z.writestr(name, data)
+            z.close()
+            zi = zipimport.zipimporter(TEMP_ZIP)
+            self.assertEquals(data, zi.get_data(name))
+        finally:
+            z.close()
+            os.remove(TEMP_ZIP)
+
+    def testImporterAttr(self):
+        src = """if 1:  # indent hack
+        def get_file():
+            return __file__
+        if __importer__.get_data("some.data") != "some data":
+            raise AssertionError, "bad data"\n"""
+        pyc = make_pyc(compile(src, "<???>", "exec"), NOW)
+        files = {TESTMOD + pyc_ext: (NOW, pyc),
+                 "some.data": (NOW, "some data")}
+        self.doTest(pyc_ext, files, TESTMOD)
+
+
+class CompressedZipImportTestCase(UncompressedZipImportTestCase):
+    compression = ZIP_DEFLATED
+
+
+if __name__ == "__main__":
+    test_support.run_unittest(UncompressedZipImportTestCase)
+    test_support.run_unittest(CompressedZipImportTestCase)

Modules/Setup.dist

@@ -113,6 +113,10 @@ errno errnomodule.c		# posix (UNIX) errno values
 _sre _sre.c			# Fredrik Lundh's new regular expressions
 _codecs _codecsmodule.c		# access to the builtin codecs and codec registry
 
+# The zipimport module is always imported at startup. Having it as a
+# builtin module avoids some bootstrapping problems and reduces overhead.
+zipimport zipimport.c
+
 # The rest of the modules listed in this file are all commented out by
 # default.  Usually they can be detected and built as dynamically
 # loaded modules by the new setup.py script added in Python 2.1.  If

Modules/getpath.c

@@ -365,6 +365,7 @@ calculate_path(void)
     char *path = getenv("PATH");
     char *prog = Py_GetProgramName();
     char argv0_path[MAXPATHLEN+1];
+    char zip_path[MAXPATHLEN+1];
     int pfound, efound; /* 1 if found; -1 if found build directory */
     char *buf;
     size_t bufsz;
@@ -483,6 +484,18 @@ calculate_path(void)
     else
         reduce(prefix);
 
+    strncpy(zip_path, prefix, MAXPATHLEN);
+    if (pfound > 0) { /* Use the reduced prefix returned by Py_GetPrefix() */
+        reduce(zip_path);
+        reduce(zip_path);
+    }
+    else
+        strncpy(zip_path, PREFIX, MAXPATHLEN);
+    joinpath(zip_path, "lib/python00.zip");
+    bufsz = strlen(zip_path);	/* Replace "00" with version */
+    zip_path[bufsz - 6] = VERSION[0];
+    zip_path[bufsz - 5] = VERSION[2];
+
     if (!(efound = search_for_exec_prefix(argv0_path, home))) {
         if (!Py_FrozenFlag)
             fprintf(stderr,
@@ -521,6 +534,7 @@ calculate_path(void)
         defpath = delim + 1;
     }
 
+    bufsz += strlen(zip_path) + 1;
     bufsz += strlen(exec_prefix) + 1;
 
     /* This is the only malloc call in this file */
@@ -541,6 +555,10 @@ calculate_path(void)
         else
             buf[0] = '\0';
 
+        /* Next is the default zip path */
+        strcat(buf, zip_path);
+        strcat(buf, delimiter);
+
         /* Next goes merge of compile-time $PYTHONPATH with
          * dynamically located prefix.
          */

PC/config.c

@@ -43,6 +43,7 @@ extern void initxreadlines(void);
 extern void init_weakref(void);
 extern void init_hotshot(void);
 extern void initxxsubtype(void);
+extern void initzipimport(void);
 extern void init_random(void);
 
 /* XXX tim: what's the purpose of ADDMODULE MARKER? */
@@ -98,6 +99,7 @@ struct _inittab _PyImport_Inittab[] = {
 	{"_random", init_random},
 
 	{"xxsubtype", initxxsubtype},
+	{"zipimport", initzipimport},
 
 /* XXX tim: what's the purpose of ADDMODULE MARKER? */
 /* -- ADDMODULE MARKER 2 -- */

PC/getpathp.c

@@ -81,6 +81,7 @@
 
 static char prefix[MAXPATHLEN+1];
 static char progpath[MAXPATHLEN+1];
+static char dllpath[MAXPATHLEN+1];
 static char *module_search_path = NULL;
 
 
@@ -350,6 +351,7 @@ get_progpath(void)
 	char *prog = Py_GetProgramName();
 
 #ifdef MS_WINDOWS
+	extern HANDLE PyWin_DLLhModule;
 #ifdef UNICODE
 	WCHAR wprogpath[MAXPATHLEN+1];
 	/* Windows documents that GetModuleFileName() will "truncate",
@@ -357,6 +359,14 @@ get_progpath(void)
 	   PLUS Windows itself defines MAX_PATH as the same, but anyway...
 	*/
 	wprogpath[MAXPATHLEN]=_T('\0');
+	if (PyWin_DLLhModule &&
+	    GetModuleFileName(PyWin_DLLhModule, wprogpath, MAXPATHLEN)) {
+		WideCharToMultiByte(CP_ACP, 0, 
+		                    wprogpath, -1, 
+		                    dllpath, MAXPATHLEN+1, 
+		                    NULL, NULL);
+	}
+	wprogpath[MAXPATHLEN]=_T('\0')';
 	if (GetModuleFileName(NULL, wprogpath, MAXPATHLEN)) {
 		WideCharToMultiByte(CP_ACP, 0, 
 		                    wprogpath, -1, 
@@ -366,6 +376,9 @@ get_progpath(void)
 	}
 #else
 	/* static init of progpath ensures final char remains \0 */
+	if (PyWin_DLLhModule)
+		if (!GetModuleFileName(PyWin_DLLhModule, dllpath, MAXPATHLEN))
+			dllpath[0] = 0;
 	if (GetModuleFileName(NULL, progpath, MAXPATHLEN))
 		return;
 #endif
@@ -427,6 +440,8 @@ calculate_path(void)
 	int skiphome, skipdefault;
 	char *machinepath = NULL;
 	char *userpath = NULL;
+	char zip_path[MAXPATHLEN+1];
+	size_t len;
 #endif
 
 	get_progpath();
@@ -447,6 +462,21 @@ calculate_path(void)
 
 
 #ifdef MS_WINDOWS
+	/* Calculate zip archive path */
+	if (dllpath[0])		/* use name of python DLL */
+		strncpy(zip_path, dllpath, MAXPATHLEN);
+	else			/* use name of executable program */
+		strncpy(zip_path, progpath, MAXPATHLEN);
+	len = strlen(zip_path);
+	if (len > 4) {
+		zip_path[len-3] = 'z';	/* change ending to "zip" */
+		zip_path[len-2] = 'i';
+		zip_path[len-1] = 'p';
+	}
+	else {
+		zip_path[0] = 0;
+	}
+ 
 	skiphome = pythonhome==NULL ? 0 : 1;
 	machinepath = getpythonregpath(HKEY_LOCAL_MACHINE, skiphome);
 	userpath = getpythonregpath(HKEY_CURRENT_USER, skiphome);
@@ -458,14 +488,15 @@ calculate_path(void)
 
 	/* We need to construct a path from the following parts.
 	   (1) the PYTHONPATH environment variable, if set;
-	   (2) for Win32, the machinepath and userpath, if set;
+	   (2) for Win32, the zip archive file path;
-	   (3) the PYTHONPATH config macro, with the leading "."
+	   (3) for Win32, the machinepath and userpath, if set;
+	   (4) the PYTHONPATH config macro, with the leading "."
 	       of each component replaced with pythonhome, if set;
-	   (4) the directory containing the executable (argv0_path).
+	   (5) the directory containing the executable (argv0_path).
-	   The length calculation calculates #3 first.
+	   The length calculation calculates #4 first.
 	   Extra rules:
-	   - If PYTHONHOME is set (in any way) item (2) is ignored.
+	   - If PYTHONHOME is set (in any way) item (3) is ignored.
-	   - If registry values are used, (3) and (4) are ignored.
+	   - If registry values are used, (4) and (5) are ignored.
 	*/
 
 	/* Calculate size of return buffer */
@@ -487,6 +518,7 @@ calculate_path(void)
 		bufsz += strlen(userpath) + 1;
 	if (machinepath)
 		bufsz += strlen(machinepath) + 1;
+	bufsz += strlen(zip_path) + 1;
 #endif
 	if (envpath != NULL)
 		bufsz += strlen(envpath) + 1;
@@ -518,6 +550,11 @@ calculate_path(void)
 		*buf++ = DELIM;
 	}
 #ifdef MS_WINDOWS
+	if (zip_path[0]) {
+		strcpy(buf, zip_path);
+		buf = strchr(buf, '\0');
+		*buf++ = DELIM;
+	}
 	if (userpath) {
 		strcpy(buf, userpath);
 		buf = strchr(buf, '\0');

PCbuild/pythoncore.dsp

@@ -549,5 +549,9 @@ SOURCE=..\Modules\xxsubtype.c
 
 SOURCE=..\Modules\yuvconvert.c
 # End Source File
+# Begin Source File
+
+SOURCE=..\Modules\zipimport.c
+# End Source File
 # End Target
 # End Project

Python/import.c

@@ -152,6 +152,72 @@ _PyImport_Init(void)
 	}
 }
 
+void
+_PyImportHooks_Init(void)
+{
+	PyObject *v, *path_hooks = NULL, *zimpimport;
+	int err = 0;
+
+	/* adding sys.path_hooks and sys.path_importer_cache, setting up
+	   zipimport */
+
+	if (Py_VerboseFlag)
+		PySys_WriteStderr("# installing zipimport hook\n");
+
+	v = PyList_New(0);
+	if (v == NULL)
+		goto error;
+	err = PySys_SetObject("meta_path", v);
+	Py_DECREF(v);
+	if (err)
+		goto error;
+	v = PyDict_New();
+	if (v == NULL)
+		goto error;
+	err = PySys_SetObject("path_importer_cache", v);
+	Py_DECREF(v);
+	if (err)
+		goto error;
+	path_hooks = PyList_New(0);
+	if (path_hooks == NULL)
+		goto error;
+	err = PySys_SetObject("path_hooks", path_hooks);
+	if (err) {
+  error:
+		PyErr_Print();
+		Py_FatalError("initializing sys.meta_path, sys.path_hooks or "
+			      "path_importer_cache failed");
+	}
+	zimpimport = PyImport_ImportModule("zipimport");
+	if (zimpimport == NULL) {
+		PyErr_Clear(); /* No zip import module -- okay */
+		if (Py_VerboseFlag)
+			PySys_WriteStderr("# can't import zipimport\n");
+	}
+	else {
+		PyObject *zipimporter = PyObject_GetAttrString(zimpimport,
+							       "zipimporter");
+		Py_DECREF(zimpimport);
+		if (zipimporter == NULL) {
+			PyErr_Clear(); /* No zipimporter object -- okay */
+			if (Py_VerboseFlag)
+				PySys_WriteStderr(
+				    "# can't import zipimport.zimimporter\n");
+		}
+		else {
+			/* sys.path_hooks.append(zipimporter) */
+			err = PyList_Append(path_hooks, zipimporter);
+			Py_DECREF(zipimporter);
+			if (err)
+				goto error;
+			if (Py_VerboseFlag)
+				PySys_WriteStderr(
+					"# installed zipimport hook\n");
+		}
+	}
+	Py_DECREF(path_hooks);
+}
+
 void
 _PyImport_Fini(void)
 {
@@ -246,6 +312,7 @@ static char* sys_deletes[] = {
 	"path", "argv", "ps1", "ps2", "exitfunc",
 	"exc_type", "exc_value", "exc_traceback",
 	"last_type", "last_value", "last_traceback",
+	"path_hooks", "path_importer_cache", "meta_path",
 	NULL
 };
 
@@ -808,9 +875,9 @@ load_source_module(char *name, char *pathname, FILE *fp)
 
 
 /* Forward */
-static PyObject *load_module(char *, FILE *, char *, int);
+static PyObject *load_module(char *, FILE *, char *, int, PyObject *);
-static struct filedescr *find_module(char *, PyObject *,
+static struct filedescr *find_module(char *, char *, PyObject *,
-				     char *, size_t, FILE **);
+				     char *, size_t, FILE **, PyObject **);
 static struct _frozen *find_frozen(char *name);
 
 /* Load a package and return its module object WITH INCREMENTED
@@ -848,7 +915,7 @@ load_package(char *name, char *pathname)
 		goto cleanup;
 	}
 	buf[0] = '\0';
-	fdp = find_module("__init__", path, buf, sizeof(buf), &fp);
+	fdp = find_module(name, "__init__", path, buf, sizeof(buf), &fp, NULL);
 	if (fdp == NULL) {
 		if (PyErr_ExceptionMatches(PyExc_ImportError)) {
 			PyErr_Clear();
@@ -857,7 +924,7 @@ load_package(char *name, char *pathname)
 			m = NULL;
 		goto cleanup;
 	}
-	m = load_module(name, fp, buf, fdp->type);
+	m = load_module(name, fp, buf, fdp->type, NULL);
 	if (fp != NULL)
 		fclose(fp);
   cleanup:
@@ -885,6 +952,61 @@ is_builtin(char *name)
 }
 
 
+/* Return an importer object for a sys.path/pkg.__path__ item 'p',
+   possibly by fetching it from the path_importer_cache dict. If it
+   wasn't yet cached, traverse path_hooks until it a hook is found
+   that can handle the path item. Return None if no hook could;
+   this tells our caller it should fall back to the builtin
+   import mechanism. Cache the result in path_importer_cache.
+   Returns a borrowed reference. */
+
+static PyObject *
+get_path_importer(PyObject *path_importer_cache, PyObject *path_hooks,
+		  PyObject *p)
+{
+	PyObject *importer;
+	int j, nhooks;
+
+	/* These conditions are the caller's responsibility: */
+	assert(PyList_Check(path_hooks));
+	assert(PyDict_Check(path_importer_cache));
+
+	nhooks = PyList_Size(path_hooks);
+	if (nhooks < 0)
+		return NULL; /* Shouldn't happen */
+
+	importer = PyDict_GetItem(path_importer_cache, p);
+	if (importer != NULL)
+		return importer;
+
+	/* set path_importer_cache[p] to None to avoid recursion */
+	if (PyDict_SetItem(path_importer_cache, p, Py_None) != 0)
+		return NULL;
+
+	for (j = 0; j < nhooks; j++) {
+		PyObject *hook = PyList_GetItem(path_hooks, j);
+		if (hook == NULL)
+			return NULL;
+		importer = PyObject_CallFunction(hook, "O", p);
+		if (importer != NULL)
+			break;
+
+		if (!PyErr_ExceptionMatches(PyExc_ImportError)) {
+			return NULL;
+		}
+		PyErr_Clear();
+	}
+	if (importer == NULL)
+		importer = Py_None;
+	else if (importer != Py_None) {
+		int err = PyDict_SetItem(path_importer_cache, p, importer);
+		Py_DECREF(importer);
+		if (err != 0)
+			return NULL;
+	}
+	return importer;
+}
+
 /* Search the path (default sys.path) for a module.  Return the
    corresponding filedescr struct, and (via return arguments) the
    pathname and an open file.  Return NULL if the module is not found. */
@@ -896,16 +1018,18 @@ extern FILE *PyWin_FindRegisteredModule(const char *, struct filedescr **,
 
 static int case_ok(char *, int, int, char *);
 static int find_init_module(char *); /* Forward */
+static struct filedescr importhookdescr = {"", "", IMP_HOOK};
 
 static struct filedescr *
-find_module(char *realname, PyObject *path, char *buf, size_t buflen,
+find_module(char *fullname, char *subname, PyObject *path, char *buf,
-	    FILE **p_fp)
+	    size_t buflen, FILE **p_fp, PyObject **p_loader)
 {
 	int i, npath;
 	size_t len, namelen;
 	struct filedescr *fdp = NULL;
 	char *filemode;
 	FILE *fp = NULL;
+	PyObject *path_hooks, *path_importer_cache;
 #ifndef RISCOS
 	struct stat statbuf;
 #endif
@@ -918,13 +1042,50 @@ find_module(char *realname, PyObject *path, char *buf, size_t buflen,
 	size_t saved_namelen;
 	char *saved_buf = NULL;
 #endif
+	if (p_loader != NULL)
+		*p_loader = NULL;
 
-	if (strlen(realname) > MAXPATHLEN) {
+	if (strlen(subname) > MAXPATHLEN) {
 		PyErr_SetString(PyExc_OverflowError,
 				"module name is too long");
 		return NULL;
 	}
-	strcpy(name, realname);
+	strcpy(name, subname);
+
+	/* sys.meta_path import hook */
+	if (p_loader != NULL) {
+		PyObject *meta_path;
+
+		meta_path = PySys_GetObject("meta_path");
+		if (meta_path == NULL || !PyList_Check(meta_path)) {
+			PyErr_SetString(PyExc_ImportError,
+					"sys.meta_path must be a list of "
+					"import hooks");
+			return NULL;
+		}
+		Py_INCREF(meta_path);  /* zap guard */
+		npath = PyList_Size(meta_path);
+		for (i = 0; i < npath; i++) {
+			PyObject *loader;
+			PyObject *hook = PyList_GetItem(meta_path, i);
+			loader = PyObject_CallMethod(hook, "find_module",
+						     "sO", fullname,
+						     path != NULL ?
+						     path : Py_None);
+			if (loader == NULL) {
+				Py_DECREF(meta_path);
+				return NULL;  /* true error */
+			}
+			if (loader != Py_None) {
+				/* a loader was found */
+				*p_loader = loader;
+				Py_DECREF(meta_path);
+				return &importhookdescr;
+			}
+			Py_DECREF(loader);
+		}
+		Py_DECREF(meta_path);
+	}
 
 	if (path != NULL && PyString_Check(path)) {
 		/* The only type of submodule allowed inside a "frozen"
@@ -978,6 +1139,22 @@ find_module(char *realname, PyObject *path, char *buf, size_t buflen,
 				"sys.path must be a list of directory names");
 		return NULL;
 	}
+
+	path_hooks = PySys_GetObject("path_hooks");
+	if (path_hooks == NULL || !PyList_Check(path_hooks)) {
+		PyErr_SetString(PyExc_ImportError,
+				"sys.path_hooks must be a list of "
+				"import hooks");
+		return NULL;
+	}
+	path_importer_cache = PySys_GetObject("path_importer_cache");
+	if (path_importer_cache == NULL ||
+	    !PyDict_Check(path_importer_cache)) {
+		PyErr_SetString(PyExc_ImportError,
+				"sys.path_importer_cache must be a dict");
+		return NULL;
+	}
+
 	npath = PyList_Size(path);
 	namelen = strlen(name);
 	for (i = 0; i < npath; i++) {
@@ -1005,6 +1182,33 @@ find_module(char *realname, PyObject *path, char *buf, size_t buflen,
 			Py_XDECREF(copy);
 			continue; /* v contains '\0' */
 		}
+
+		/* sys.path_hooks import hook */
+		if (p_loader != NULL) {
+			PyObject *importer;
+
+			importer = get_path_importer(path_importer_cache,
+						     path_hooks, v);
+			if (importer == NULL)
+				return NULL;
+			/* Note: importer is a borrowed reference */
+			if (importer != Py_None) {
+				PyObject *loader;
+				loader = PyObject_CallMethod(importer,
+							     "find_module",
+							     "s", fullname);
+				if (loader == NULL)
+					return NULL;  /* error */
+				if (loader != Py_None) {
+					/* a loader was found */
+					*p_loader = loader;
+					return &importhookdescr;
+				}
+				Py_DECREF(loader);
+			}
+			/* no hook was successful, use builtin import */
+		}
+
 #ifdef macintosh
 		/*
 		** Speedup: each sys.path item is interned, and
@@ -1079,7 +1283,7 @@ find_module(char *realname, PyObject *path, char *buf, size_t buflen,
 			 * dynamically loaded module we're going to try,
 			 * truncate the name before trying
 			 */
-			if (strlen(realname) > 8) {
+			if (strlen(subname) > 8) {
 				/* is this an attempt to load a C extension? */
 				const struct filedescr *scan;
 				scan = _PyImport_DynLoadFiletab;
@@ -1092,7 +1296,7 @@ find_module(char *realname, PyObject *path, char *buf, size_t buflen,
 				if (scan->suffix != NULL) {
 					/* yes, so truncate the name */
 					namelen = 8;
-					len -= strlen(realname) - namelen;
+					len -= strlen(subname) - namelen;
 					buf[len] = '\0';
 				}
 			}
@@ -1444,7 +1648,7 @@ static int init_builtin(char *); /* Forward */
    its module object WITH INCREMENTED REFERENCE COUNT */
 
 static PyObject *
-load_module(char *name, FILE *fp, char *buf, int type)
+load_module(char *name, FILE *fp, char *buf, int type, PyObject *loader)
 {
 	PyObject *modules;
 	PyObject *m;
@@ -1523,6 +1727,16 @@ load_module(char *name, FILE *fp, char *buf, int type)
 		Py_INCREF(m);
 		break;
 
+	case IMP_HOOK: {
+		if (loader == NULL) {
+			PyErr_SetString(PyExc_ImportError,
+					"import hook without loader");
+			return NULL;
+		}
+		m = PyObject_CallMethod(loader, "load_module", "s", name);
+		break;
+	}
+
 	default:
 		PyErr_Format(PyExc_ImportError,
 			     "Don't know how to import %.200s (type code %d)",
@@ -1978,7 +2192,7 @@ import_submodule(PyObject *mod, char *subname, char *fullname)
 		Py_INCREF(m);
 	}
 	else {
-		PyObject *path;
+		PyObject *path, *loader = NULL;
 		char buf[MAXPATHLEN+1];
 		struct filedescr *fdp;
 		FILE *fp = NULL;
@@ -1995,7 +2209,8 @@ import_submodule(PyObject *mod, char *subname, char *fullname)
 		}
 
 		buf[0] = '\0';
-		fdp = find_module(subname, path, buf, MAXPATHLEN+1, &fp);
+		fdp = find_module(fullname, subname, path, buf, MAXPATHLEN+1,
+				  &fp, &loader);
 		Py_XDECREF(path);
 		if (fdp == NULL) {
 			if (!PyErr_ExceptionMatches(PyExc_ImportError))
@@ -2004,7 +2219,8 @@ import_submodule(PyObject *mod, char *subname, char *fullname)
 			Py_INCREF(Py_None);
 			return Py_None;
 		}
-		m = load_module(fullname, fp, buf, fdp->type);
+		m = load_module(fullname, fp, buf, fdp->type, loader);
+		Py_XDECREF(loader);
 		if (fp)
 			fclose(fp);
 		if (mod != Py_None) {
@@ -2080,11 +2296,11 @@ PyImport_ReloadModule(PyObject *m)
 			PyErr_Clear();
 	}
 	buf[0] = '\0';
-	fdp = find_module(subname, path, buf, MAXPATHLEN+1, &fp);
+	fdp = find_module(name, subname, path, buf, MAXPATHLEN+1, &fp, NULL);
 	Py_XDECREF(path);
 	if (fdp == NULL)
 		return NULL;
-	m = load_module(name, fp, buf, fdp->type);
+	m = load_module(name, fp, buf, fdp->type, NULL);
 	if (fp)
 		fclose(fp);
 	return m;
@@ -2228,7 +2444,7 @@ call_find_module(char *name, PyObject *path)
 	pathname[0] = '\0';
 	if (path == Py_None)
 		path = NULL;
-	fdp = find_module(name, path, pathname, MAXPATHLEN+1, &fp);
+	fdp = find_module(NULL, name, path, pathname, MAXPATHLEN+1, &fp, NULL);
 	if (fdp == NULL)
 		return NULL;
 	if (fp != NULL) {
@@ -2465,7 +2681,7 @@ imp_load_module(PyObject *self, PyObject *args)
 		if (fp == NULL)
 			return NULL;
 	}
-	return load_module(name, fp, pathname, type);
+	return load_module(name, fp, pathname, type, NULL);
 }
 
 static PyObject *
@@ -2579,6 +2795,7 @@ initimp(void)
 	if (setint(d, "C_BUILTIN", C_BUILTIN) < 0) goto failure;
 	if (setint(d, "PY_FROZEN", PY_FROZEN) < 0) goto failure;
 	if (setint(d, "PY_CODERESOURCE", PY_CODERESOURCE) < 0) goto failure;
+	if (setint(d, "IMP_HOOK", IMP_HOOK) < 0) goto failure;
 
   failure:
 	;

Python/importdl.h

@@ -16,7 +16,8 @@ enum filetype {
 	PKG_DIRECTORY,
 	C_BUILTIN,
 	PY_FROZEN,
-	PY_CODERESOURCE /* Mac only */
+	PY_CODERESOURCE, /* Mac only */
+	IMP_HOOK
 };
 
 struct filedescr {

Python/pythonrun.c

@@ -161,6 +161,8 @@ Py_Initialize(void)
 	/* phase 2 of builtins */
 	_PyImport_FixupExtension("__builtin__", "__builtin__");
 
+	_PyImportHooks_Init();
+
 	initsigs(); /* Signal handling stuff, including initintr() */
 
 	initmain(); /* Module __main__ */