[gnome-db] read-only connections

[Rodrigo Moya <rodrigo gnome-db org>]

Hi

There is a feature that we need to have, which is the ability to open
read-only connections. This is needed for things such as the
Gnumeric/Abiword plugins, which could be a big security hole.

So, I've added the needed stuff to the library to allow this, and the
only thing missing is the implementation of this in the providers. This
just involves the *_transaction methods and execute_command. For the
xaction methods, it's as easy as:

	if (gda_connection_get_options (cnc) &
GDA_CONNECTION_OPTIONS_READ_ONLY) {
		gda_connection_add_error_string (cnc, _("Transactions are not
supported in read-only mode"));
		return FALSE;
	}

before any other code.

For the execute_command, things are more complicated, since you'll have
to check which command it is and determine if it can be executed or not.
For MySQL, I've done an ugly implementation (in
gda-mysql-provider.c|process_sql_commands):

	/* if the connection is in read-only mode, just allow SELECT,
	   SHOW commands */
	if (options & GDA_CONNECTION_OPTIONS_READ_ONLY) {
		gchar *s;
		/* FIXME: maybe there's a better way of doing this? */
		s = g_strstrip (g_strdup (arr[n]));
		if (g_ascii_strncasecmp (s, "select", strlen ("select")) &&
		    g_ascii_strncasecmp (s, "show", strlen ("show"))) {
			gda_connection_add_error_string (
				cnc, "Command '%s' cannot be executed in read-only mode", arr[n]);
			break;
		}

		g_free (s);
	}

it's ugly but works.

So, please, could people working on providers come up to some solution
for their providers for this? It would be really nice to have it in all
providers for the next release (0.10).

cheers