1nbd_set_debug_callback(3)           LIBNBD           nbd_set_debug_callback(3)
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NAME

6       nbd_set_debug_callback - set the debug callback
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SYNOPSIS

9        #include <libnbd.h>
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11        typedef struct {
12          int (*callback) (void *user_data, const char *context,
13                           const char *msg);
14          void *user_data;
15          void (*free) (void *user_data);
16        } nbd_debug_callback;
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18        int nbd_set_debug_callback (struct nbd_handle *h,
19                                    nbd_debug_callback debug_callback);
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DESCRIPTION

22       Set the debug callback.  This function is called when the library emits
23       debug messages, when debugging is enabled on a handle.  The callback
24       parameters are "user_data" passed to this function, the name of the
25       libnbd function emitting the debug message ("context"), and the message
26       itself ("msg").  If no debug callback is set on a handle then messages
27       are printed on "stderr".
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29       The callback should not call "nbd_*" APIs on the same handle since it
30       can be called while holding the handle lock and will cause a deadlock.
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RETURN VALUE

33       If the call is successful the function returns 0.
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ERRORS

36       On error "-1" is returned.
37
38       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
39       of the error.
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41       The following parameters must not be NULL: "h".  For more information
42       see "Non-NULL parameters" in libnbd(3).
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VERSION

45       This function first appeared in libnbd 1.0.
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47       If you need to test if this function is available at compile time check
48       if the following macro is defined:
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50        #define LIBNBD_HAVE_NBD_SET_DEBUG_CALLBACK 1
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SEE ALSO

53       nbd_create(3), libnbd(3).
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AUTHORS

56       Eric Blake
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58       Richard W.M. Jones
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61       Copyright (C) 2019-2021 Red Hat Inc.
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LICENSE

64       This library is free software; you can redistribute it and/or modify it
65       under the terms of the GNU Lesser General Public License as published
66       by the Free Software Foundation; either version 2 of the License, or
67       (at your option) any later version.
68
69       This library is distributed in the hope that it will be useful, but
70       WITHOUT ANY WARRANTY; without even the implied warranty of
71       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
72       Lesser General Public License for more details.
73
74       You should have received a copy of the GNU Lesser General Public
75       License along with this library; if not, write to the Free Software
76       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
77       02110-1301 USA
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81libnbd-1.14.2                     2023-01-03         nbd_set_debug_callback(3)
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