Index: Lib/os.py
===================================================================
--- Lib/os.py	(révision 80702)
+++ Lib/os.py	(copie de travail)
@@ -355,8 +355,9 @@
         return
     last_exc = saved_exc = None
     saved_tb = None
+    file = fsencode(file)
     for dir in get_exec_path(env):
-        fullname = path.join(dir, file)
+        fullname = path.join(fsencode(dir), file)
         try:
             exec_func(fullname, *argrest)
         except error as e:
@@ -387,29 +388,30 @@
 from _abcoll import MutableMapping  # Can't use collections (bootstrap)
 
 class _Environ(MutableMapping):
-    def __init__(self, environ, keymap, putenv, unsetenv):
-        self.keymap = keymap
+    def __init__(self, data, encodekey, decodekey, encodevalue, decodevalue, putenv, unsetenv):
+        self.encodekey = encodekey
+        self.decodekey = decodekey
+        self.encodevalue = encodevalue
+        self.decodevalue = decodevalue
         self.putenv = putenv
         self.unsetenv = unsetenv
-        self.data = data = {}
-        for key, value in environ.items():
-            data[keymap(key)] = str(value)
+        self.data = data
 
     def __getitem__(self, key):
-        return self.data[self.keymap(key)]
+        value = self.data[self.encodekey(key)]
+        return self.decodevalue(value)
 
     def __setitem__(self, key, value):
-        value = str(value)
         self.putenv(key, value)
-        self.data[self.keymap(key)] = value
+        self.data[self.encodekey(key)] = self.encodevalue(value)
 
     def __delitem__(self, key):
         self.unsetenv(key)
-        del self.data[self.keymap(key)]
+        del self.data[self.encodekey(key)]
 
     def __iter__(self):
         for key in self.data:
-            yield key
+            yield self.decodekey(key)
 
     def __len__(self):
         return len(self.data)
@@ -439,22 +441,56 @@
 else:
     __all__.append("unsetenv")
 
+def fsdecode(value):
+    """
+    file system to unicode
+    """
+    if isinstance(value, str):
+        return value
+    else:
+        return value.decode(sys.getfilesystemencoding(), 'surrogateescape')
+
+if name in ('os2', 'nt', 'ce'):
+    fsencode = fsdecode
+else:
+    def fsencode(value):
+        """
+        unicode to file system
+        """
+        if isinstance(value, bytes):
+            return value
+        else:
+            return value.encode(sys.getfilesystemencoding(), 'surrogateescape')
+
 if name in ('os2', 'nt'): # Where Env Var Names Must Be UPPERCASE
-    _keymap = lambda key: str(key.upper())
+    def _keymap(key):
+        return fsencode(key).upper()
 else:  # Where Env Var Names Can Be Mixed Case
-    _keymap = lambda key: str(key)
+    _keymap = fsencode
 
-environ = _Environ(environ, _keymap, _putenv, _unsetenv)
+data = {}
+for key, value in environ.items():
+    data[_keymap(key)] = fsencode(value)
 
+# unicode environ
+environ = _Environ(data, _keymap, fsdecode, fsencode, fsdecode, _putenv, _unsetenv)
 
 def getenv(key, default=None):
     """Get an environment variable, return None if it doesn't exist.
     The optional second argument can specify an alternate default."""
-    if isinstance(key, bytes):
-        key = key.decode(sys.getfilesystemencoding(), "surrogateescape")
     return environ.get(key, default)
 __all__.append("getenv")
 
+if name not in ('os2', 'nt'):
+    # bytes environ
+    environb = _Environ(data, _keymap, fsencode, fsencode, fsencode, _putenv, _unsetenv)
+
+    def getenvb(key, default=None):
+        """Get an environment variable, return None if it doesn't exist.
+        The optional second argument can specify an alternate default."""
+        return environb.get(key, default)
+    __all__.append("getenvb")
+
 def _exists(name):
     return name in globals()
 
Index: Lib/test/test_os.py
===================================================================
--- Lib/test/test_os.py	(révision 80702)
+++ Lib/test/test_os.py	(copie de travail)
@@ -439,7 +439,22 @@
         # Supplied PATH environment variable
         self.assertSequenceEqual(test_path, os.get_exec_path(test_env))
 
+    @unittest.skipIf(sys.platform == "win32", "POSIX specific test")
+    def test_environb(self):
+        # os.environ -> os.environb
+        value = 'euro\u20ac'
+        os.environ['unicode'] = value
+        self.assertEquals(os.environ['unicode'], value)
+        value_bytes = os.fsencode(value)
+        self.assertEquals(os.environb[b'unicode'], value_bytes)
 
+        # os.environb -> os.environ
+        value = b'\xff'
+        os.environb[b'bytes'] = value
+        self.assertEquals(os.environb['bytes'], value)
+        value_str = os.fsdecode(value)
+        self.assertEquals(os.environ['bytes'], value_str)
+
 class WalkTests(unittest.TestCase):
     """Tests for os.walk()."""
 
Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c	(révision 80702)
+++ Modules/posixmodule.c	(copie de travail)
@@ -493,14 +493,12 @@
 		char *p = strchr(*e, '=');
 		if (p == NULL)
 			continue;
-		k = PyUnicode_Decode(*e, (int)(p-*e),
-				     Py_FileSystemDefaultEncoding, "surrogateescape");
+		k = PyBytes_FromStringAndSize(*e, (int)(p-*e));
 		if (k == NULL) {
 			PyErr_Clear();
 			continue;
 		}
-		v = PyUnicode_Decode(p+1, strlen(p+1),
-				     Py_FileSystemDefaultEncoding, "surrogateescape");
+		v = PyBytes_FromStringAndSize(p+1, strlen(p+1));
 		if (v == NULL) {
 			PyErr_Clear();
 			Py_DECREF(k);