Implemented PEP 370

Doc/library/site.rst

@@ -85,3 +85,51 @@ Note that for some non-Unix systems, ``sys.prefix`` and ``sys.exec_prefix`` are
 empty, and the path manipulations are skipped; however the import of
 :mod:`sitecustomize` is still attempted.
 
+
+.. data:: PREFIXES
+
+   A list of prefixes for site package directories
+
+   .. versionadded:: 2.6
+
+
+.. data:: ENABLE_USER_SITE
+
+   Flag showing the status of the user site directory. True means the
+   user site directory is enabled and added to sys.path. When the flag
+   is None the user site directory is disabled for security reasons.
+
+   .. versionadded:: 2.6
+
+
+.. data:: USER_SITE
+
+   Path to the user site directory for the current Python version or None
+
+   .. versionadded:: 2.6
+
+
+.. data:: USER_BASE
+
+   Path to the base directory for user site directories
+
+   .. versionadded:: 2.6
+
+
+.. envvar:: PYTHONNOUSERSITE
+
+   .. versionadded:: 2.6
+
+
+.. envvar:: PYTHONUSERBASE
+
+   .. versionadded:: 2.6
+
+
+.. function:: addsitedir(sitedir, known_paths=None)
+
+   Adds a directory to sys.path and processes its pth files.
+
+
+XXX Update documentation
+XXX document python -m site --user-base --user-site

Doc/using/cmdline.rst

@@ -21,7 +21,7 @@ Command line
 
 When invoking Python, you may specify any of these options::
 
-    python [-dEiOQStuUvxX3?] [-c command | -m module-name | script | - ] [args]
+    python [-dEiOQsStuUvxX3?] [-c command | -m module-name | script | - ] [args]
 
 The most common use case is, of course, a simple invocation of a script::
 
@@ -240,6 +240,17 @@ Miscellaneous options
       :pep:`238` -- Changing the division operator
 
 
+.. cmdoption:: -s
+
+   Don't add user site directory to sys.path
+
+   .. versionadded:: 2.6
+
+   .. seealso::
+
+      :pep:`370` -- Per user site-packages directory
+
+
 .. cmdoption:: -S
 
    Disable the import of the module :mod:`site` and the site-dependent
@@ -471,6 +482,28 @@ These environment variables influence Python's behavior.
    .. versionadded:: 2.6
 
 
+.. envvar:: PYTHONNOUSERSITE
+
+   If this is set, Python won't add the user site directory to sys.path
+
+   .. versionadded:: 2.6
+
+   .. seealso::
+
+      :pep:`370` -- Per user site-packages directory
+
+
+.. envvar:: PYTHONUSERBASE
+
+   Sets the base directory for the user site directory
+
+   .. versionadded:: 2.6
+
+   .. seealso::
+
+      :pep:`370` -- Per user site-packages directory
+
+
 .. envvar:: PYTHONEXECUTABLE
 
    If this environment variable is set, ``sys.argv[0]`` will be set to its

Include/pydebug.h

@@ -19,6 +19,7 @@ PyAPI_DATA(int) Py_UnicodeFlag;
 PyAPI_DATA(int) Py_IgnoreEnvironmentFlag;
 PyAPI_DATA(int) Py_DivisionWarningFlag;
 PyAPI_DATA(int) Py_DontWriteBytecodeFlag;
+PyAPI_DATA(int) Py_NoUserSiteDirectory;
 /* _XXX Py_QnewFlag should go away in 3.0.  It's true iff -Qnew is passed,
   on the command line, and is used in 2.2 by ceval.c to make all "/" divisions
   true divisions (which they will be in 3.0). */

Lib/distutils/command/install.py

@@ -18,6 +18,9 @@ from distutils.file_util import write_file
 from distutils.util import convert_path, subst_vars, change_root
 from distutils.util import get_platform
 from distutils.errors import DistutilsOptionError
+from site import USER_BASE
+from site import USER_SITE
+
 
 if sys.version < "2.2":
     WINDOWS_SCHEME = {
@@ -51,7 +54,21 @@ INSTALL_SCHEMES = {
         'scripts': '$base/bin',
         'data'   : '$base',
         },
+    'unix_user': {
+        'purelib': '$usersite',
+        'platlib': '$usersite',
+        'headers': '$userbase/include/python$py_version_short/$dist_name',
+        'scripts': '$userbase/bin',
+        'data'   : '$userbase',
+        },
     'nt': WINDOWS_SCHEME,
+    'nt_user': {
+        'purelib': '$usersite',
+        'platlib': '$usersite',
+        'headers': '$userbase/Python$py_version_nodot/Include/$dist_name',
+        'scripts': '$userbase/Scripts',
+        'data'   : '$userbase',
+        },
     'mac': {
         'purelib': '$base/Lib/site-packages',
         'platlib': '$base/Lib/site-packages',
@@ -59,13 +76,27 @@ INSTALL_SCHEMES = {
         'scripts': '$base/Scripts',
         'data'   : '$base',
         },
+    'mac_user': {
+        'purelib': '$usersite',
+        'platlib': '$usersite',
+        'headers': '$userbase/$py_version_short/include/$dist_name',
+        'scripts': '$userbase/bin',
+        'data'   : '$userbase',
+        },
     'os2': {
         'purelib': '$base/Lib/site-packages',
         'platlib': '$base/Lib/site-packages',
         'headers': '$base/Include/$dist_name',
         'scripts': '$base/Scripts',
         'data'   : '$base',
-        }
+        },
+    'os2_home': {
+        'purelib': '$usersite',
+        'platlib': '$usersite',
+        'headers': '$userbase/include/python$py_version_short/$dist_name',
+        'scripts': '$userbase/bin',
+        'data'   : '$userbase',
+        },
     }
 
 # The keys to an installation scheme; if any new types of files are to be
@@ -86,6 +117,8 @@ class install (Command):
          "(Unix only) prefix for platform-specific files"),
         ('home=', None,
          "(Unix only) home directory to install under"),
+        ('user', None,
+         "install in user site-package '%s'" % USER_SITE),
 
         # Or, just set the base director(y|ies)
         ('install-base=', None,
@@ -137,7 +170,7 @@ class install (Command):
          "filename in which to record list of installed files"),
         ]
 
-    boolean_options = ['compile', 'force', 'skip-build']
+    boolean_options = ['compile', 'force', 'skip-build', 'user']
     negative_opt = {'no-compile' : 'compile'}
 
 
@@ -148,6 +181,7 @@ class install (Command):
         self.prefix = None
         self.exec_prefix = None
         self.home = None
+        self.user = 0
 
         # These select only the installation base; it's up to the user to
         # specify the installation scheme (currently, that means supplying
@@ -166,6 +200,8 @@ class install (Command):
         self.install_lib = None         # set to either purelib or platlib
         self.install_scripts = None
         self.install_data = None
+        self.install_userbase = USER_BASE
+        self.install_usersite = USER_SITE
 
         self.compile = None
         self.optimize = None
@@ -241,6 +277,11 @@ class install (Command):
             raise DistutilsOptionError, \
                   "must supply either home or prefix/exec-prefix -- not both"
 
+        if self.user and (self.prefix or self.exec_prefix or self.home or
+                self.install_base or self.install_platbase):
+            raise DistutilsOptionError("can't combine user with with prefix/"
+                                       "exec_prefix/home or install_(plat)base")
+
         # Next, stuff that's wrong (or dubious) only on certain platforms.
         if os.name != "posix":
             if self.exec_prefix:
@@ -276,10 +317,13 @@ class install (Command):
                             'dist_fullname': self.distribution.get_fullname(),
                             'py_version': py_version,
                             'py_version_short': py_version[0:3],
+                            'py_version_nodot': py_version[0] + py_version[2],
                             'sys_prefix': prefix,
                             'prefix': prefix,
                             'sys_exec_prefix': exec_prefix,
                             'exec_prefix': exec_prefix,
+                            'userbase': self.install_userbase,
+                            'usersite': self.install_usersite,
                            }
         self.expand_basedirs()
 
@@ -301,6 +345,10 @@ class install (Command):
 
         self.dump_dirs("post-expand_dirs()")
 
+        # Create directories in the home dir:
+        if self.user:
+            self.create_home_path()
+
         # Pick the actual directory to install all modules to: either
         # install_purelib or install_platlib, depending on whether this
         # module distribution is pure or not.  Of course, if the user
@@ -315,7 +363,8 @@ class install (Command):
         # Convert directories from Unix /-separated syntax to the local
         # convention.
         self.convert_paths('lib', 'purelib', 'platlib',
-                           'scripts', 'data', 'headers')
+                           'scripts', 'data', 'headers',
+                           'userbase', 'usersite')
 
         # Well, we're not actually fully completely finalized yet: we still
         # have to deal with 'extra_path', which is the hack for allowing
@@ -376,7 +425,13 @@ class install (Command):
                       "installation scheme is incomplete")
             return
 
-        if self.home is not None:
+        if self.user:
+            if self.install_userbase is None:
+                raise DistutilsPlatformError(
+                    "User base directory is not specified")
+            self.install_base = self.install_platbase = self.install_userbase
+            self.select_scheme("unix_user")
+        elif self.home is not None:
             self.install_base = self.install_platbase = self.home
             self.select_scheme("unix_home")
         else:
@@ -401,7 +456,13 @@ class install (Command):
 
     def finalize_other (self):          # Windows and Mac OS for now
 
-        if self.home is not None:
+        if self.user:
+            if self.install_userbase is None:
+                raise DistutilsPlatformError(
+                    "User base directory is not specified")
+            self.install_base = self.install_platbase = self.install_userbase
+            self.select_scheme(os.name + "_user")
+        elif self.home is not None:
             self.install_base = self.install_platbase = self.home
             self.select_scheme("unix_home")
         else:
@@ -431,7 +492,7 @@ class install (Command):
         for attr in attrs:
             val = getattr(self, attr)
             if val is not None:
-                if os.name == 'posix':
+                if os.name == 'posix' or os.name == 'nt':
                     val = os.path.expanduser(val)
                 val = subst_vars(val, self.config_vars)
                 setattr(self, attr, val)
@@ -496,6 +557,16 @@ class install (Command):
             attr = "install_" + name
             setattr(self, attr, change_root(self.root, getattr(self, attr)))
 
+    def create_home_path(self):
+        """Create directories under ~
+        """
+        if not self.user:
+            return
+        home = convert_path(os.path.expanduser("~"))
+        for name, path in self.config_vars.iteritems():
+            if path.startswith(home) and not os.path.isdir(path):
+                self.debug_print("os.makedirs('%s', 0700)" % path)
+                os.makedirs(path, 0700)
 
     # -- Command execution methods -------------------------------------
 

Lib/site.py

@@ -62,11 +62,21 @@ import sys
 import os
 import __builtin__
 
+# Prefixes for site-packages; add additional prefixes like /usr/local here
+PREFIXES = [sys.prefix, sys.exec_prefix]
+# Enable per user site-packages directory
+# set it to False to disable the feature or True to force the feature
+ENABLE_USER_SITE = None
+# for distutils.commands.install
+USER_SITE = None
+USER_BASE = None
+
 
 def makepath(*paths):
     dir = os.path.abspath(os.path.join(*paths))
     return dir, os.path.normcase(dir)
 
+
 def abs__file__():
     """Set all module' __file__ attribute to an absolute path"""
     for m in sys.modules.values():
@@ -77,6 +87,7 @@ def abs__file__():
         except AttributeError:
             continue
 
+
 def removeduppaths():
     """ Remove duplicate entries from sys.path along with making them
     absolute"""
@@ -107,6 +118,7 @@ def addbuilddir():
     s = os.path.join(os.path.dirname(sys.path[-1]), s)
     sys.path.append(s)
 
+
 def _init_pathinfo():
     """Return a set containing all existing directory entries from sys.path"""
     d = set()
@@ -119,6 +131,7 @@ def _init_pathinfo():
             continue
     return d
 
+
 def addpackage(sitedir, name, known_paths):
     """Process a .pth file within the site-packages directory:
        For each line in the file, either combine it with sitedir to a path
@@ -134,11 +147,11 @@ def addpackage(sitedir, name, known_paths):
         f = open(fullname, "rU")
     except IOError:
         return
-    try:
+    with f:
         for line in f:
             if line.startswith("#"):
                 continue
-            if line.startswith("import ") or line.startswith("import\t"):
+            if line.startswith(("import ", "import\t")):
                 exec line
                 continue
             line = line.rstrip()
@@ -146,12 +159,11 @@ def addpackage(sitedir, name, known_paths):
             if not dircase in known_paths and os.path.exists(dir):
                 sys.path.append(dir)
                 known_paths.add(dircase)
-    finally:
-        f.close()
     if reset:
         known_paths = None
     return known_paths
 
+
 def addsitedir(sitedir, known_paths=None):
     """Add 'sitedir' argument to sys.path if missing and handle .pth files in
     'sitedir'"""
@@ -167,48 +179,115 @@ def addsitedir(sitedir, known_paths=None):
         names = os.listdir(sitedir)
     except os.error:
         return
-    names.sort()
-    for name in names:
-        if name.endswith(os.extsep + "pth"):
-            addpackage(sitedir, name, known_paths)
+    dotpth = os.extsep + "pth"
+    names = [name for name in names if name.endswith(dotpth)]
+    for name in sorted(names):
+        addpackage(sitedir, name, known_paths)
     if reset:
         known_paths = None
     return known_paths
 
+
+def check_enableusersite():
+    """Check if user site directory is safe for inclusion
+
+    The functions tests for the command line flag (including environment var),
+    process uid/gid equal to effective uid/gid.
+
+    None: Disabled for security reasons
+    False: Disabled by user (command line option)
+    True: Safe and enabled
+    """
+    if sys.flags.no_user_site:
+        return False
+
+    if hasattr(os, "getuid") and hasattr(os, "geteuid"):
+        # check process uid == effective uid
+        if os.geteuid() != os.getuid():
+            return None
+    if hasattr(os, "getgid") and hasattr(os, "getegid"):
+        # check process gid == effective gid
+        if os.getegid() != os.getgid():
+            return None
+
+    return True
+
+
+def addusersitepackages(known_paths):
+    """Add a per user site-package to sys.path
+
+    Each user has its own python directory with site-packages in the
+    home directory.
+
+    USER_BASE is the root directory for all Python versions
+
+    USER_SITE is the user specific site-packages directory
+
+    USER_SITE/.. can be used for data.
+    """
+    global USER_BASE, USER_SITE, ENABLE_USER_SITE
+    env_base = os.environ.get("PYTHONUSERBASE", None)
+
+    def joinuser(*args):
+        return os.path.expanduser(os.path.join(*args))
+
+    #if sys.platform in ('os2emx', 'riscos'):
+    #    # Don't know what to put here
+    #    USER_BASE = ''
+    #    USER_SITE = ''
+    if os.name == "nt":
+        base = os.environ.get("APPDATA") or "~"
+        USER_BASE = env_base if env_base else joinuser(base, "Python")
+        USER_SITE = os.path.join(USER_BASE,
+                                 "Python" + sys.version[0] + sys.version[2],
+                                 "site-packages")
+    else:
+        USER_BASE = env_base if env_base else joinuser("~", ".local")
+        USER_SITE = os.path.join(USER_BASE, "lib",
+                                 "python" + sys.version[:3],
+                                 "site-packages")
+
+    if ENABLE_USER_SITE and os.path.isdir(USER_SITE):
+        addsitedir(USER_SITE, known_paths)
+    return known_paths
+
+
 def addsitepackages(known_paths):
     """Add site-packages (and possibly site-python) to sys.path"""
-    prefixes = [sys.prefix]
-    if sys.exec_prefix != sys.prefix:
-        prefixes.append(sys.exec_prefix)
-    for prefix in prefixes:
-        if prefix:
-            if sys.platform in ('os2emx', 'riscos'):
-                sitedirs = [os.path.join(prefix, "Lib", "site-packages")]
-            elif os.sep == '/':
-                sitedirs = [os.path.join(prefix,
-                                         "lib",
-                                         "python" + sys.version[:3],
-                                         "site-packages"),
-                            os.path.join(prefix, "lib", "site-python")]
-            else:
-                sitedirs = [prefix, os.path.join(prefix, "lib", "site-packages")]
-            if sys.platform == 'darwin':
-                # for framework builds *only* we add the standard Apple
-                # locations. Currently only per-user, but /Library and
-                # /Network/Library could be added too
-                if 'Python.framework' in prefix:
-                    home = os.environ.get('HOME')
-                    if home:
-                        sitedirs.append(
-                            os.path.join(home,
-                                         'Library',
-                                         'Python',
-                                         sys.version[:3],
-                                         'site-packages'))
-            for sitedir in sitedirs:
-                if os.path.isdir(sitedir):
-                    addsitedir(sitedir, known_paths)
-    return None
+    sitedirs = []
+    seen = []
+
+    for prefix in PREFIXES:
+        if not prefix or prefix in seen:
+            continue
+        seen.append(prefix)
+
+        if sys.platform in ('os2emx', 'riscos'):
+            sitedirs.append(os.path.join(prefix, "Lib", "site-packages"))
+        elif os.sep == '/':
+            sitedirs.append(os.path.join(prefix, "lib",
+                                        "python" + sys.version[:3],
+                                        "site-packages"))
+            sitedirs.append(os.path.join(prefix, "lib", "site-python"))
+        else:
+            sitedirs.append(prefix)
+            sitedirs.append(os.path.join(prefix, "lib", "site-packages"))
+
+        if sys.platform == "darwin":
+            # for framework builds *only* we add the standard Apple
+            # locations. Currently only per-user, but /Library and
+            # /Network/Library could be added too
+            if 'Python.framework' in prefix:
+                sitedirs.append(
+                    os.path.expanduser(
+                        os.path.join("~", "Library", "Python",
+                                     sys.version[:3], "site-packages")))
+
+    for sitedir in sitedirs:
+        if os.path.isdir(sitedir):
+            addsitedir(sitedir, known_paths)
+
+    return known_paths
 
 
 def setBEGINLIBPATH():
@@ -395,13 +474,26 @@ def execsitecustomize():
         pass
 
 
+def execusercustomize():
+    """Run custom user specific code, if available."""
+    try:
+        import usercustomize
+    except ImportError:
+        pass
+
+
 def main():
+    global ENABLE_USER_SITE
+
     abs__file__()
-    paths_in_sys = removeduppaths()
+    known_paths = removeduppaths()
     if (os.name == "posix" and sys.path and
         os.path.basename(sys.path[-1]) == "Modules"):
         addbuilddir()
-    paths_in_sys = addsitepackages(paths_in_sys)
+    if ENABLE_USER_SITE is None:
+        ENABLE_USER_SITE = check_enableusersite()
+    known_paths = addusersitepackages(known_paths)
+    known_paths = addsitepackages(known_paths)
     if sys.platform == 'os2emx':
         setBEGINLIBPATH()
     setquit()
@@ -410,6 +502,8 @@ def main():
     aliasmbcs()
     setencoding()
     execsitecustomize()
+    if ENABLE_USER_SITE:
+        execusercustomize()
     # Remove sys.setdefaultencoding() so that users cannot change the
     # encoding after initialization.  The test for presence is needed when
     # this module is run as a script, because this code is executed twice.
@@ -418,11 +512,54 @@ def main():
 
 main()
 
-def _test():
-    print "sys.path = ["
-    for dir in sys.path:
-        print "    %r," % (dir,)
-    print "]"
+def _script():
+    help = """\
+    %s [--user-base] [--user-site]
+
+    Without arguments print some useful information
+    With arguments print the value of USER_BASE and/or USER_SITE separated
+    by '%s'.
+
+    Exit codes with --user-base or --user-site:
+      0 - user site directory is enabled
+      1 - user site diretory is disabled by user
+      2 - uses site directory is disabled by super user
+          or for security reasons
+     >2 - unknown error
+    """
+    args = sys.argv[1:]
+    if not args:
+        print "sys.path = ["
+        for dir in sys.path:
+            print "    %r," % (dir,)
+        print "]"
+        print "USER_BASE: %r (%s)" % (USER_BASE,
+            "exists" if os.path.isdir(USER_BASE) else "doesn't exist")
+        print "USER_SITE: %r (%s)" % (USER_SITE,
+            "exists" if os.path.isdir(USER_SITE) else "doesn't exist")
+        print "ENABLE_USER_SITE: %r" %  ENABLE_USER_SITE
+        sys.exit(0)
+
+    buffer = []
+    if '--user-base' in args:
+        buffer.append(USER_BASE)
+    if '--user-site' in args:
+        buffer.append(USER_SITE)
+
+    if buffer:
+        print os.pathsep.join(buffer)
+        if ENABLE_USER_SITE:
+            sys.exit(0)
+        elif ENABLE_USER_SITE is False:
+            sys.exit(1)
+        elif ENABLE_USER_SITE is None:
+            sys.exit(2)
+        else:
+            sys.exit(3)
+    else:
+        import textwrap
+        print textwrap.dedent(help % (sys.argv[0], os.pathsep))
+        sys.exit(10)
 
 if __name__ == '__main__':
-    _test()
+    _script()

Lib/test/test_site.py

@@ -10,6 +10,7 @@ import __builtin__
 import os
 import sys
 import encodings
+import subprocess
 # Need to make sure to not import 'site' if someone specified ``-S`` at the
 # command-line.  Detect this by just making sure 'site' has not been imported
 # already.
@@ -18,6 +19,11 @@ if "site" in sys.modules:
 else:
     raise TestSkipped("importation of site.py suppressed")
 
+if not os.path.isdir(site.USER_SITE):
+    # need to add user site directory for tests
+    os.makedirs(site.USER_SITE)
+    site.addsitedir(site.USER_SITE)
+
 class HelperFunctionsTests(unittest.TestCase):
     """Tests for helper functions.
 
@@ -30,7 +36,7 @@ class HelperFunctionsTests(unittest.TestCase):
         """Save a copy of sys.path"""
         self.sys_path = sys.path[:]
 
-    def tearDown(self):
+
         """Restore sys.path"""
         sys.path = self.sys_path
 
@@ -90,6 +96,33 @@ class HelperFunctionsTests(unittest.TestCase):
         finally:
             pth_file.cleanup()
 
+    def test_s_option(self):
+        usersite = site.USER_SITE
+        self.assert_(usersite in sys.path)
+
+        rc = subprocess.call([sys.executable, '-c',
+            'import sys; sys.exit("%s" in sys.path)' % usersite])
+        self.assertEqual(rc, 1)
+
+        rc = subprocess.call([sys.executable, '-s', '-c',
+            'import sys; sys.exit("%s" in sys.path)' % usersite])
+        self.assertEqual(rc, 0)
+
+        env = os.environ.copy()
+        env["PYTHONNOUSERSITE"] = "1"
+        rc = subprocess.call([sys.executable, '-c',
+            'import sys; sys.exit("%s" in sys.path)' % usersite],
+            env=env)
+        self.assertEqual(rc, 0)
+
+        env = os.environ.copy()
+        env["PYTHONUSERBASE"] = "/tmp"
+        rc = subprocess.call([sys.executable, '-c',
+            'import sys, site; sys.exit(site.USER_BASE.startswith("/tmp"))'],
+            env=env)
+        self.assertEqual(rc, 1)
+
+
 class PthFile(object):
     """Helper class for handling testing of .pth files"""
 

Misc/NEWS

@@ -20,6 +20,8 @@ Core and builtins
 - Patch #2617: Reserved -J and -X arguments for Jython, IronPython and other
   implementations of Python. 
 
+- Implemented PEP 370: Per user site-packages directory
+
 Extension Modules
 -----------------
 

Modules/main.c

@@ -40,7 +40,7 @@ static char **orig_argv;
 static int  orig_argc;
 
 /* command line options */
-#define BASE_OPTS "3bBc:dEhiJm:OQ:StuUvVW:xX?"
+#define BASE_OPTS "3bBc:dEhiJm:OQ:sStuUvVW:xX?"
 
 #ifndef RISCOS
 #define PROGRAM_OPTS BASE_OPTS
@@ -72,6 +72,7 @@ static char *usage_2 = "\
 -O     : optimize generated bytecode slightly; also PYTHONOPTIMIZE=x\n\
 -OO    : remove doc-strings in addition to the -O optimizations\n\
 -Q arg : division options: -Qold (default), -Qwarn, -Qwarnall, -Qnew\n\
+-s     : don't add user site directory to sys.path; also PYTHONNOUSERSITE\n\
 -S     : don't imply 'import site' on initialization\n\
 -t     : issue warnings about inconsistent tab usage (-tt: issue errors)\n\
 ";
@@ -359,6 +360,10 @@ Py_Main(int argc, char **argv)
 			Py_DontWriteBytecodeFlag++;
 			break;
 
+		case 's':
+			Py_NoUserSiteDirectory++;
+			break;
+
 		case 'S':
 			Py_NoSiteFlag++;
 			break;
@@ -431,6 +436,10 @@ Py_Main(int argc, char **argv)
 	    (p = Py_GETENV("PYTHONUNBUFFERED")) && *p != '\0')
 		unbuffered = 1;
 
+	if (!Py_NoUserSiteDirectory &&
+	    (p = Py_GETENV("PYTHONNOUSERSITE")) && *p != '\0')
+		Py_NoUserSiteDirectory = 1;
+
 	if (command == NULL && module == NULL && _PyOS_optind < argc &&
 	    strcmp(argv[_PyOS_optind], "-") != 0)
 	{

Python/pythonrun.c

@@ -82,6 +82,7 @@ int Py_IgnoreEnvironmentFlag; /* e.g. PYTHONPATH, PYTHONHOME */
   on the command line, and is used in 2.2 by ceval.c to make all "/" divisions
   true divisions (which they will be in 2.3). */
 int _Py_QnewFlag = 0;
+int Py_NoUserSiteDirectory = 0; /* for -s and site.py */
 
 /* PyModule_GetWarningsModule is no longer necessary as of 2.6
 since _warnings is builtin.  This API should not be used. */

Python/sysmodule.c

@@ -1101,7 +1101,7 @@ svnversion_init(void)
 		shortbranch[len] = '\0';
 	}
 	else {
-		Py_FatalError("bad HeadURL");
+		Py_FatalError("bad HeadURL"); 
 		return;
 	}
 
@@ -1158,7 +1158,7 @@ static PyStructSequence_Field flags_fields[] = {
 	{"interactive",		"-i"},
 	{"optimize",		"-O or -OO"},
 	{"dont_write_bytecode",	"-B"},
-	/* {"no_user_site",	"-s"}, */
+	{"no_user_site",	"-s"},
 	{"no_site",		"-S"},
 	{"ignore_environment",	"-E"},
 	{"tabcheck",		"-t or -tt"},
@@ -1178,9 +1178,9 @@ static PyStructSequence_Desc flags_desc = {
 	flags__doc__,	/* doc */
 	flags_fields,	/* fields */
 #ifdef RISCOS
-	14
+	15
 #else
-	13
+	14
 #endif
 };
 
@@ -1205,7 +1205,7 @@ make_flags(void)
 	SetFlag(Py_InteractiveFlag);
 	SetFlag(Py_OptimizeFlag);
 	SetFlag(Py_DontWriteBytecodeFlag);
-	/* SetFlag(Py_NoUserSiteDirectory); */
+	SetFlag(Py_NoUserSiteDirectory);
 	SetFlag(Py_NoSiteFlag);
 	SetFlag(Py_IgnoreEnvironmentFlag);
 	SetFlag(Py_TabcheckFlag);