=head1 NAME

nbd_aio_opt_list_meta_context_queries - request list of available meta
contexts, using explicit query

=head1 SYNOPSIS

 #include <libnbd.h>

 typedef struct {
   int (*callback) (void *user_data, const char *name);
   void *user_data;
   void (*free) (void *user_data);
 } nbd_context_callback;

 typedef struct {
   int (*callback) (void *user_data, int *error);
   void *user_data;
   void (*free) (void *user_data);
 } nbd_completion_callback;

 int nbd_aio_opt_list_meta_context_queries (
       struct nbd_handle *h, char **queries,
       nbd_context_callback context_callback,
       nbd_completion_callback completion_callback
     );

=head1 DESCRIPTION

Request that the server list
available meta contexts associated with
the export previously specified by the most recent
L<nbd_set_export_name(3)> or L<nbd_connect_uri(3)>, and with an
explicit list of queries provided as a parameter (see
L<nbd_aio_opt_list_meta_context(3)> if you want to reuse an
implicit query list instead).  This can only be
used if L<nbd_set_opt_mode(3)> enabled option mode.

To determine when the request completes, wait for
L<nbd_aio_is_connecting(3)> to return false.  Or supply the optional
C<completion_callback> which will be invoked as described in
L<libnbd(3)/Completion callbacks>, except that it is automatically
retired regardless of return value.  Note that detecting whether the
server returns an error (as is done by the return value of the
synchronous counterpart) is only possible with a completion
callback.

=head1 RETURN VALUE

This call returns an integer E<ge> C<0>.

=head1 ERRORS

On error C<-1> is returned.

Refer to L<libnbd(3)/ERROR HANDLING>
for how to get further details of the error.

The following parameters must not be NULL: C<h>, C<queries>.
For more information see L<libnbd(3)/Non-NULL parameters>.

=head1 HANDLE STATE

nbd_aio_opt_list_meta_context_queries
can be called when the handle is in the following state:

 ┌─────────────────────────────────────┬─────────────────────────┐
 │ Handle created, before connecting   │ ❌ error                │
 │ Connecting                          │ ❌ error                │
 │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
 │ Connected to the server             │ ❌ error                │
 │ Connection shut down                │ ❌ error                │
 │ Handle dead                         │ ❌ error                │
 └─────────────────────────────────────┴─────────────────────────┘

=head1 VERSION

This function first appeared in libnbd 1.16.

If you need to test if this function is available at compile time
check if the following macro is defined:

 #define LIBNBD_HAVE_NBD_AIO_OPT_LIST_META_CONTEXT_QUERIES 1

=head1 SEE ALSO

L<nbd_aio_is_connecting(3)>,
L<nbd_aio_opt_list_meta_context(3)>,
L<nbd_connect_uri(3)>,
L<nbd_create(3)>,
L<nbd_opt_list_meta_context_queries(3)>,
L<nbd_set_export_name(3)>,
L<nbd_set_opt_mode(3)>,
L<libnbd(3)>.

=head1 AUTHORS

Eric Blake

Richard W.M. Jones

=head1 COPYRIGHT

Copyright Red Hat
