1nbd_aio_pread_structured(3)         LIBNBD         nbd_aio_pread_structured(3)
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NAME

6       nbd_aio_pread_structured - read from the NBD server
7

SYNOPSIS

9        #include <libnbd.h>
10
11        typedef struct {
12          int (*callback) (void *user_data, const void *subbuf,
13                           size_t count, uint64_t offset,
14                           unsigned status, int *error);
15          void *user_data;
16          void (*free) (void *user_data);
17        } nbd_chunk_callback;
18
19        typedef struct {
20          int (*callback) (void *user_data, int *error);
21          void *user_data;
22          void (*free) (void *user_data);
23        } nbd_completion_callback;
24
25        int64_t nbd_aio_pread_structured (struct nbd_handle *h,
26                                          void *buf, size_t count,
27                                          uint64_t offset,
28                                          nbd_chunk_callback chunk_callback,
29                                          nbd_completion_callback completion_callback,
30                                          uint32_t flags);
31

DESCRIPTION

33       Issue a read command to the NBD server.
34
35       To check if the command completed, call nbd_aio_command_completed(3).
36       Or supply the optional "completion_callback" which will be invoked as
37       described in "Completion callbacks" in libnbd(3).
38
39       Other parameters behave as documented in nbd_pread_structured(3).
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RETURN VALUE

42       This call returns the 64 bit cookie of the command.  The cookie is ≥ 1.
43       Cookies are unique (per libnbd handle, not globally).
44

ERRORS

46       On error "-1" is returned.
47
48       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
49       of the error.
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HANDLE STATE

52       The handle must be connected and finished handshaking with the server,
53       otherwise this call will return an error.
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VERSION

56       This function first appeared in libnbd 1.0.
57
58       If you need to test if this function is available at compile time check
59       if the following macro is defined:
60
61        #define LIBNBD_HAVE_NBD_AIO_PREAD_STRUCTURED 1
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SEE ALSO

64       nbd_aio_command_completed(3), nbd_aio_pread(3), nbd_create(3),
65       nbd_pread_structured(3), "Issuing asynchronous commands" in libnbd(3),
66       libnbd(3).
67

AUTHORS

69       Eric Blake
70
71       Richard W.M. Jones
72

74       Copyright (C) 2019 Red Hat Inc.
75

LICENSE

77       This library is free software; you can redistribute it and/or modify it
78       under the terms of the GNU Lesser General Public License as published
79       by the Free Software Foundation; either version 2 of the License, or
80       (at your option) any later version.
81
82       This library is distributed in the hope that it will be useful, but
83       WITHOUT ANY WARRANTY; without even the implied warranty of
84       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
85       Lesser General Public License for more details.
86
87       You should have received a copy of the GNU Lesser General Public
88       License along with this library; if not, write to the Free Software
89       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
90       02110-1301 USA
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94libnbd-1.3.7                      2020-04-23       nbd_aio_pread_structured(3)
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