=head1 NAME

nbd_aio_opt_list_meta_context - request list of available meta
contexts, using implicit 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 (
       struct nbd_handle *h,
       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 a
list of queries from prior calls to L<nbd_add_meta_context(3)>
(see L<nbd_aio_opt_list_meta_context_queries(3)> if you want to
supply an explicit 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>.
For more information see L<libnbd(3)/Non-NULL parameters>.

=head1 HANDLE STATE

nbd_aio_opt_list_meta_context
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 1.6.

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 1

=head1 SEE ALSO

L<nbd_add_meta_context(3)>,
L<nbd_aio_is_connecting(3)>,
L<nbd_aio_opt_list_meta_context_queries(3)>,
L<nbd_connect_uri(3)>,
L<nbd_create(3)>,
L<nbd_opt_list_meta_context(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
