nbd_set_debug_callback(3)           LIBNBD           nbd_set_debug_callback(3)


NAME
       nbd_set_debug_callback - set the debug callback

SYNOPSIS
        #include <libnbd.h>

        typedef struct {
          int (*callback) (void *user_data, const char *context,
                           const char *msg);
          void *user_data;
          void (*free) (void *user_data);
        } nbd_debug_callback;

        int nbd_set_debug_callback (
              struct nbd_handle *h,
              nbd_debug_callback debug_callback
            );

DESCRIPTION
       Set the debug callback.  This function is called when the library emits
       debug messages, when debugging is enabled on a handle.  The callback
       parameters are "user_data" passed to this function, the name of the
       libnbd function emitting the debug message ("context"), and the message
       itself ("msg").  If no debug callback is set on a handle then messages
       are printed on "stderr".

       The callback should not call "nbd_*" APIs on the same handle since it
       can be called while holding the handle lock and will cause a deadlock.

RETURN VALUE
       If the call is successful the function returns 0.

ERRORS
       On error -1 is returned.

       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
       of the error.

       The following parameters must not be NULL: "h".  For more information
       see "Non-NULL parameters" in libnbd(3).

VERSION
       This function first appeared in libnbd 1.0.

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

        #define LIBNBD_HAVE_NBD_SET_DEBUG_CALLBACK 1

SEE ALSO
       nbd_create(3), libnbd(3).

AUTHORS
       Eric Blake

       Richard W.M. Jones

COPYRIGHT
       Copyright Red Hat

LICENSE
       This library is free software; you can redistribute it and/or modify it
       under the terms of the GNU Lesser General Public License as published
       by the Free Software Foundation; either version 2 of the License, or
       (at your option) any later version.

       This library is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       Lesser General Public License for more details.

       You should have received a copy of the GNU Lesser General Public
       License along with this library; if not, write to the Free Software
       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
       02110-1301 USA

libnbd-1.20.0                     2024-05-31         nbd_set_debug_callback(3)