Module to assist with advanced user manipulation

Currently holds the logic to ascertain the system groups
for a system user.

confluent_server/confluent/userutil.py

@@ -0,0 +1,40 @@
+from ctypes import *
+from ctypes.util import find_library
+import grp
+import pwd
+import os
+libc = cdll.LoadLibrary(find_library('libc'))
+_getgrouplist = libc.getgrouplist
+_getgrouplist.restype = c_int32
+
+
+class TooSmallException(Exception):
+    def __init__(self, count):
+        self.count = count
+        super(TooSmallException, self).__init__()
+
+
+def getgrouplist(name, gid, ng=32):
+    _getgrouplist.argtypes = [c_char_p, c_uint, POINTER(c_uint * ng), POINTER(c_int)]
+    glist = (c_uint * ng)()
+    nglist = c_int(ng)
+    count = _getgrouplist(name, gid, byref(glist), byref(nglist))
+    if count < 0:
+        raise TooSmallException(nglist.value)
+    for gidx in range(count):
+        gent = glist[gidx]
+        yield grp.getgrgid(gent).gr_name
+
+
+def grouplist(username):
+    pent = pwd.getpwnam(username)
+    try:
+        groups = getgrouplist(pent.pw_name, pent.pw_gid)
+    except TooSmallException as e:
+        groups = getgrouplist(pent.pw_name, pent.pw_gid, e.count)
+    return list(groups)
+
+if __name__ == '__main__':
+    import sys
+    print(repr(grouplist(sys.argv[1])))
+