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neko_daemonizer_dante/daemonizer/_privdrop_unix.py

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+''' 
+LICENSING
+-------------------------------------------------
+
+daemoniker: Cross-platform daemonization tools.
+    Copyright (C) 2016 Muterra, Inc.
+    
+    Contributors
+    ------------
+    Nick Badger 
+        badg@muterra.io | badg@nickbadger.com | nickbadger.com
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the 
+    Free Software Foundation, Inc.,
+    51 Franklin Street, 
+    Fifth Floor, 
+    Boston, MA  02110-1301 USA
+
+------------------------------------------------------
+
+This was written with heavy consultation of the following resources:
+    Chad J. Schroeder, Creating a daemon the Python way (Python recipe) 
+        http://code.activestate.com/recipes/
+        278731-creating-a-daemon-the-python-way/
+    Ilya Otyutskiy, Daemonize
+        https://github.com/thesharp/daemonize
+    David Mytton, unknown, et al: A simple daemon in Python
+        http://www.jejik.com/articles/2007/02/
+        a_simple_unix_linux_daemon_in_python/www.boxedice.com
+    
+'''
+
+# Global dependencies
+import os
+import sys
+import signal
+import logging
+import atexit
+import traceback
+import shutil
+
+# Intra-package dependencies
+from .utils import platform_specificker
+from .utils import default_to
+
+_SUPPORTED_PLATFORM = platform_specificker(
+    linux_choice = True,
+    win_choice = False,
+    cygwin_choice = False,
+    osx_choice = True,
+    # Dunno if this is a good idea but might as well try
+    other_choice = True
+)
+
+if _SUPPORTED_PLATFORM:
+    import fcntl
+    import pwd
+    import grp
+    import resource
+
+
+# ###############################################
+# Boilerplate
+# ###############################################
+
+
+import logging
+logger = logging.getLogger(__name__)
+
+# Control * imports.
+__all__ = [
+    # 'Inquisitor', 
+]
+
+
+# ###############################################
+# Library
+# ###############################################
+
+        
+def _setuser(user):
+    ''' Normalizes user to a uid and sets the current uid, or does 
+    nothing if user is None.
+    '''
+    if user is None:
+        return
+        
+    # Normalize group to gid
+    elif isinstance(user, str):
+        uid = pwd.getpwnam(user).pw_uid
+    # The group is already a gid.
+    else:
+        uid = user
+        
+    try:
+        os.setuid(uid)
+    except OSError:
+        self.logger.error('Unable to change user.')
+        sys.exit(1)
+    
+    
+def _setgroup(group):
+    ''' Normalizes group to a gid and sets the current gid, or does 
+    nothing if group is None.
+    '''
+    if group is None:
+        return
+        
+    # Normalize group to gid
+    elif isinstance(group, str):
+        gid = grp.getgrnam(group).gr_gid
+    # The group is already a gid.
+    else:
+        gid = group
+        
+    try:
+        os.setgid(gid)
+    except OSError:
+        self.logger.error('Unable to change group.')
+        sys.exit(1)
+
+
+def daemote(pid_file, user, group):
+    ''' Change gid and uid, dropping privileges.
+    
+    Either user or group may explicitly pass None to keep it the same.
+    
+    The pid_file will be chown'ed so it can still be cleaned up.
+    '''
+    if not _SUPPORTED_PLATFORM:
+        raise OSError('Daemotion is unsupported on your platform.')
+    
+    # No need to do anything special, just chown the pidfile
+    # This will also catch any bad group, user names
+    shutil.chown(pid_file, user, group)
+    
+    # Now update group and then user
+    _setgroup(group)
+    _setuser(user)