nbd_aio_opt_extended_headers - request the server to enable extended headers
#include <libnbd.h>
typedef struct {
int (*callback) (void *user_data, int *error);
void *user_data;
void (*free) (void *user_data);
} nbd_completion_callback;
int nbd_aio_opt_extended_headers (
struct nbd_handle *h,
nbd_completion_callback completion_callback
);Request that the server use extended headers, by sending NBD_OPT_EXTENDED_HEADERS. This behaves like the synchronous counterpart nbd_opt_extended_headers(3), except that it does not wait for the server's response.
To determine when the request completes, wait for nbd_aio_is_connecting(3) to return false. Or supply the optional completion_callback which will be invoked as described in "Completion callbacks" in libnbd(3), 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.
If the call is successful the function returns 0.
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).
nbd_aio_opt_extended_headers 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 │
└─────────────────────────────────────┴─────────────────────────┘This function first appeared in libnbd 1.18.
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_EXTENDED_HEADERS 1nbd_aio_is_connecting(3), nbd_create(3), nbd_opt_extended_headers(3), nbd_set_opt_mode(3), libnbd(3).
Eric Blake
Richard W.M. Jones
Copyright Red Hat
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.
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