Initial commit of change of semantics for module

The postgresql_user module has several drawbacks:
* No granularity for privileges
* PostgreSQL semantics force working on one
  database at time, at least for Tables. Which
  means that a single call can't remove all the 
  privileges for a user, and a user can't be
  removed until all the privileges are removed, 
  forcing a module failure with no way to 
  work around the issue.

Changes:
* Added the ability to specify granular privileges
  for database and tables within the database
* Report if user was removed, and add an option to 
  disable failing if user is not removed.

library/postgresql_user

@@ -34,35 +34,14 @@ def user_exists(cursor, user):
     return cursor.rowcount > 0
 
 
-def user_add(cursor, user, password, db):
+def user_add(cursor, user, password):
     """Create a new user with write access to the database"""
     query = "CREATE USER %(user)s with PASSWORD '%(password)s'"
     cursor.execute(query % {"user": user, "password": password})
-    grant_privileges(cursor, user, db)
     return True
 
-
-def has_privileges(cursor, user, db):
-    """Check if the user has create privileges on the database"""
-    query = "SELECT has_database_privilege(%(user)s, %(db)s, 'CREATE')"
-    cursor.execute(query, {'user': user, 'db': db})
-    return cursor.fetchone()[0]
-
-
-def grant_privileges(cursor, user, db):
-    """Grant all privileges on the database"""
-    query = "GRANT ALL PRIVILEGES ON DATABASE %(db)s TO %(user)s"
-    cursor.execute(query % {'user': user, 'db': db})
-
-
-def revoke_privileges(cursor, user, db):
-    """Revoke all privileges on the database"""
-    query = "REVOKE ALL PRIVILEGES ON DATABASE %(db)s FROM %(user)s"
-    cursor.execute(query % {'user': user, 'db': db})
-
-
-def user_mod(cursor, user, password, db):
-    """Update password and permissions"""
+def user_chpass(cursor, user, password):
+    """Change user password"""
     changed = False
 
     # Handle passwords.
@@ -79,28 +58,131 @@ def user_mod(cursor, user, password, db):
         if current_pass_hash != new_pass_hash:
             changed = True
 
-    # Handle privileges.
-    # For now, we just check if the user has access to the database
-    if not has_privileges(cursor, user, db):
-        grant_privileges(cursor, user, db)
-        changed = True
-
     return changed
 
+def user_delete(cursor, user):
+    """Try to remove a user. Returns True if successful otherwise False"""
+    cursor.execute("SAVEPOINT ansible_pgsql_user_delete")
+    try:
+        cursor.execute("DROP USER %s" % user)
+    except:
+        cursor.execute("ROLLBACK TO SAVEPOINT ansible_pgsql_user_delete")
+        cursor.execute("RELEASE SAVEPOINT ansible_pgsql_user_delete")
+        return False
+    
+    cursor.execute("RELEASE SAVEPOINT ansible_pgsql_user_delete")
+    return True
+
+def has_table_privilege(cursor, user, table, priv):
+    query = 'SELECT has_table_privilege(%s, %s, %s)'
+    cursor.execute(query, user, table, priv)
+    return cursor.fetchone()[0]
+
+def grant_table_privilege(cursor, user, table, priv):
+    if has_table_privilege(cursor, user, table, priv):
+        return False
+    query = 'GRANT %s ON TABLE %s TO %s' % (priv, table, user)
+    cursor.execute(query)
+    return True
+
+def revoke_table_privilege(cursor, user, table, priv):
+    if not has_table_privilege(cursor, user, table, priv):
+        return False
+    query = 'REVOKE %s ON TABLE %s FROM %s' % (priv, table, user)
+    cursor.execute(query)
+    return True
+
+
+def has_database_privilege(cursor, user, db, priv):
+    query = 'SELECT has_database_privilege(%s, %s, %s)'
+    cursor.execute(query, user, db, priv)
+    return cursor.fetchone()[0]
+
+def grant_database_privilege(cursor, user, db, priv):
+    if has_database_privilege(cursor, user, db, priv):
+        return False
+    query = 'GRANT %s ON DATABASE %s TO %s' % (priv, db, user)
+    cursor.execute(query)
+    return True
 
-def user_delete(cursor, user, db):
-    """Delete a user, first revoking privileges"""
-    revoke_privileges(cursor, user, db)
-    cursor.execute("DROP USER %(user)s" % {'user': user})
+def revoke_database_privilege(cursor, user, db, priv):
+    if not has_database_privilege(cursor, user, db, priv):
+        return False
+    query = 'REVOKE %s ON DATABASE %s FROM %s' % (priv, db, user)
+    cursor.execute(query)
     return True
 
+def revoke_privileges(cursor, user, privs):
+    if privs is None:
+        return False
 
+    changed = False
+    for type_ in privs:
+        revoke_func = {
+            'table':revoke_table_privilege,
+            'database':revoke_database_privilege
+        }[type_]
+        for name, privileges in privs[type_].iteritem():
+            for privilege in privileges:
+                changed = revoke_func(cursor, user, name, privilege)\
+                        or changed
+
+    return changed
+
+def grant_privileges(cursor, user, privs):
+    if privs is None:
+        return False
+
+    changed = False
+    for type_ in privs:
+        grant_func = {
+            'table':grant_table_privilege,
+            'database':grant_database_privilege
+        }[type_]
+        for name, privileges in privs[type_].iteritem():
+            for privilege in privileges:
+                changed = grant_func(cursor, user, name, privilege)\
+                        or changed
+
+    return changed
+
+def parse_privs(privs, db):
+    """
+    Parse privilege string to determine permissions for database db.
+    Format:
+
+        privileges[/privileges/...]
+
+    Where:
+
+        privileges := DATABASE_PRIVILEGES[,DATABASE_PRIVILEGES,...] |
+            TABLE_NAME:TABLE_PRIVILEGES[,TABLE_PRIVILEGES,...]
+    """
+    if privs is None:
+        return privs
+
+    privs = {
+        'database':{},
+        'table':{}
+    }
+    for token in privs.split('/'):
+        if ':' not in token:
+            type_ = 'database'
+            name = db
+            privileges = token
+        else:
+            type_ = 'table'
+            name, privileges = token.split(':', 1)
+        privileges = privileges.split(',')
+        
+        privs[type_][name] = privileges
+    
+    return privs
 
 # ===========================================
 # Module execution.
 #
 
-
 def main():
     module = AnsibleModule(
         argument_spec=dict(
@@ -110,13 +192,19 @@ def main():
             user=dict(required=True, aliases=['name']),
             password=dict(default=None),
             state=dict(default="present", choices=["absent", "present"]),
-            db=dict(required=True),
+            priv=dict(default=None),
+            db=dict(default=''),
+            fail_on_user=dict(default=True)
         )
     )
     user = module.params["user"]
     password = module.params["password"]
     state = module.params["state"]
+    fail_on_user = module.params["fail_on_user"]
     db = module.params["db"]
+    if db == '' and module.params["priv"] is not None:
+        module.fail_json(msg="privileges require a database to be specified")
+    privs = parse_privs(module.params["priv"], db)
 
     if not postgresqldb_found:
         module.fail_json(msg="the python psycopg2 module is required")
@@ -127,7 +215,8 @@ def main():
     params_map =  {
         "login_host":"host",
         "login_user":"user",
-        "login_password":"password"
+        "login_password":"password",
+        "db":"database" 
     }
     kw = dict( (params_map[k], v) for (k, v) in module.params.iteritems() 
               if k in params_map and v != "" )
@@ -136,24 +225,30 @@ def main():
         cursor = db_connection.cursor()
     except Exception, e:
         module.fail_json(msg="unable to connect to database: %s" % e)
-
+    
+    changed = False
     if state == "present":
         if user_exists(cursor, user):
-            changed = user_mod(cursor, user, password, db)
+            changed = user_chpass(cursor, user, password)
         else:
             if password is None:
                 msg = "password parameter required when adding a user"
                 module.fail_json(msg=msg)
-            changed = user_add(cursor, user, password, db)
-
-    elif state == "absent":
+            changed = user_add(cursor, user, password)
+        changed = grant_privileges(cursor, user, privs) or changed
+    else:
         if user_exists(cursor, user):
-            changed = user_delete(cursor, user, db)
-        else:
-            changed = False
-    # Commit the database changes
-    db_connection.commit()
-    module.exit_json(changed=changed, user=user)
+            changed = revoke_privileges(cursor, user, privs)
+            user_removed = user_delete(cursor, user)
+            changed = changed or user_removed
+
+    if fail_on_user and not user_removed:
+        msg = "unabel to remove user"
+        module.fail_json(msg=msg)
+
+    if changed:
+        db_connection.commit()
+    module.exit_json(changed=changed, user=user, user_removed=user_removed)
 
 # this is magic, see lib/ansible/module_common.py
 #<<INCLUDE_ANSIBLE_MODULE_COMMON>>