Bug 617483 – Credentials passing

- Make GCredentials instance and class structures private so it can't
   be subclassed and we don't have to worry about ABI compat
   issues. This also allows us to get rid of the GCredentialsPrivate
   struct.

 - Add a GCredentialsType enumeration that is used whenever exchanging
   pointers with the user. This allows us to support OSes with
   multiple native credential types. In particular, it allows
   supporting OSes where the native credential evolves or even changes
   over time.

 - Add g_socket_get_credentials() method.

 - Add tests for g_socket_get_credentials(). Right now this is in the
   GDBus peer-to-peer test case but we can change that later.

 - Move GTcpConnection into a separate gtk-doc page as was already
   half-done with GUnixConnection. Also finish the GUnixConnection
   move and ensure send_credentials() and receive_credentials()
   methods are in the docs. Also nuke comment about GTcpConnection
   being empty compared to its superclass.

Signed-off-by: David Zeuthen <davidz@redhat.com>

docs/reference/gio/gio-sections.txt

@@ -1741,6 +1741,7 @@ g_socket_get_protocol
 g_socket_get_remote_address
 g_socket_get_socket_type
 g_socket_speaks_ipv4
+g_socket_get_credentials
 <SUBSECTION Standard>
 GSocketClass
 G_IS_SOCKET
@@ -1797,16 +1798,6 @@ g_socket_connection_get_local_address
 g_socket_connection_get_remote_address
 g_socket_connection_get_socket
 <SUBSECTION>
-GTcpConnection
-g_tcp_connection_set_graceful_disconnect
-g_tcp_connection_get_graceful_disconnect
-<SUBSECTION>
-GUnixConnection
-g_unix_connection_receive_fd
-g_unix_connection_send_fd
-g_unix_connection_receive_credentials
-g_unix_connection_send_credentials
-<SUBSECTION>
 g_socket_connection_factory_create_connection
 g_socket_connection_factory_lookup_type
 g_socket_connection_factory_register_type
@@ -1818,18 +1809,9 @@ G_SOCKET_CONNECTION
 G_SOCKET_CONNECTION_CLASS
 G_SOCKET_CONNECTION_GET_CLASS
 G_TYPE_SOCKET_CONNECTION
-GTcpConnectionClass
-G_IS_TCP_CONNECTION
-G_IS_TCP_CONNECTION_CLASS
-G_TCP_CONNECTION
-G_TCP_CONNECTION_CLASS
-G_TCP_CONNECTION_GET_CLASS
-G_TYPE_TCP_CONNECTION
 <SUBSECTION Private>
 GSocketConnectionPrivate
 g_socket_connection_get_type
-GTcpConnectionPrivate
-g_tcp_connection_get_type
 </SECTION>
 
 <SECTION>
@@ -1838,6 +1820,8 @@ g_tcp_connection_get_type
 GUnixConnection
 g_unix_connection_receive_fd
 g_unix_connection_send_fd
+g_unix_connection_receive_credentials
+g_unix_connection_send_credentials
 <SUBSECTION Standard>
 GUnixConnectionClass
 G_IS_UNIX_CONNECTION
@@ -1851,6 +1835,25 @@ GUnixConnectionPrivate
 g_unix_connection_get_type
 </SECTION>
 
+<SECTION>
+<FILE>gtcpconnection</FILE>
+<TITLE>GTcpConnection</TITLE>
+GTcpConnection
+g_tcp_connection_set_graceful_disconnect
+g_tcp_connection_get_graceful_disconnect
+<SUBSECTION Standard>
+GTcpConnectionClass
+G_IS_TCP_CONNECTION
+G_IS_TCP_CONNECTION_CLASS
+G_TYPE_TCP_CONNECTION
+G_TCP_CONNECTION
+G_TCP_CONNECTION_CLASS
+G_TCP_CONNECTION_GET_CLASS
+<SUBSECTION Private>
+GTcpConnectionPrivate
+g_tcp_connection_get_type
+</SECTION>
+
 <SECTION>
 <FILE>gsocketcontrolmessage</FILE>
 <TITLE>GSocketControlMessage</TITLE>
@@ -2210,7 +2213,7 @@ g_unix_credentials_message_get_type
 <FILE>gcredentials</FILE>
 <TITLE>GCredentials</TITLE>
 GCredentials
-GCredentialsClass
+GCredentialsType
 g_credentials_new
 g_credentials_to_string
 g_credentials_get_native