NBDKit - Man Page

Optionally plugins can raise this exception to control how nbdkit_set_error and nbdkit_error are called​.

exception Error of Unix.error option * string

type flags = flag list

type flag =
| May_trim
| FUA
| Req_one

type fua_flag =
| FuaNone
| FuaEmulate
| FuaNative

type cache_flag =
| CacheNone
| CacheEmulate
| CacheNop

type extent = {
offset : int64 ;
length : int64 ;
is_hole : bool ;
is_zero : bool ;
}

The type of the extent list returned by ~extents

type export = {
name : string ;
description : string option ;
}

The type of the export list returned by ~list_exports

type thread_model =
| THREAD_MODEL_SERIALIZE_CONNECTIONS
| THREAD_MODEL_SERIALIZE_ALL_REQUESTS
| THREAD_MODEL_SERIALIZE_REQUESTS
| THREAD_MODEL_PARALLEL

The type of the thread model returned by ~thread_model

type buf = (char, Stdlib.Bigarray.int8_unsigned_elt, Stdlib.Bigarray.c_layout) Stdlib.Bigarray.Array1.t

Define a convenient type name for the buffer type passed to the ~pread and ~pwrite methods of NBDKit​.register_plugin ​.

As well as NBDKit​.buf_len and the blitting functions below, usual Bigarray​.Array1 functions can be used​.

val buf_len : buf -> int

Return the length of the ~pread and ~pwrite NBDKit​.buf parameter​.

val buf_create : int -> buf

Create NBDKit​.buf of the given length​.  The content is undefined​.

val buf_zeroes : int -> buf

Create NBDKit​.buf of the given length containing all zero bytes​.

val set_buf_to_zero : buf -> unit

Set all bytes in an existing buffer to zero​.

val buf_of_string : string -> buf

val string_of_buf : buf -> string

val buf_of_bytes : bytes -> buf

val bytes_of_buf : buf -> bytes

Convenience functions to convert to and from string/bytes and buf​.

These are not very efficient​.  Use Bigarray​.Array1 functions instead for efficiency​.

val blit_string_to_buf : string -> int -> buf -> int -> int -> unit

blit_string_to_buf src src_pos buf buf_pos len copies len bytes from string src+src_pos to buf+buf_pos

val blit_bytes_to_buf : bytes -> int -> buf -> int -> int -> unit

The same as above but the source is bytes

val blit_buf_to_bytes : buf -> int -> bytes -> int -> int -> unit

blit_buf_to_bytes buf buf_pos dst dst_pos len copies len bytes from buf+buf_pos to bytes dst+dst_pos

val register_plugin : name:string -> ?longname:string -> ?version:string -> ?description:string -> ?load:(unit -> unit) -> ?get_ready:(unit -> unit) -> ?after_fork:(unit -> unit) -> ?cleanup:(unit -> unit) -> ?unload:(unit -> unit) -> ?config:(string -> string -> unit) -> ?config_complete:(unit -> unit) -> ?config_help:string -> ?thread_model:(unit -> thread_model) -> ?magic_config_key:string -> ?preconnect:(bool -> unit) -> open_connection:(bool -> 'a) -> ?close:('a -> unit) -> get_size:('a -> int64) -> ?export_description:('a -> string) -> ?block_size:('a -> int * int * int64) -> ?can_cache:('a -> cache_flag) -> ?can_extents:('a -> bool) -> ?can_fast_zero:('a -> bool) -> ?can_flush:('a -> bool) -> ?can_fua:('a -> fua_flag) -> ?can_multi_conn:('a -> bool) -> ?can_trim:('a -> bool) -> ?can_write:('a -> bool) -> ?can_zero:('a -> bool) -> ?is_rotational:('a -> bool) -> pread:('a -> buf -> int64 -> flags -> unit) -> ?pwrite:('a -> buf -> int64 -> flags -> unit) -> ?flush:('a -> flags -> unit) -> ?trim:('a -> int64 -> int64 -> flags -> unit) -> ?zero:('a -> int64 -> int64 -> flags -> unit) -> ?extents:('a -> int64 -> int64 -> flags -> extent list) -> ?cache:('a -> int64 -> int64 -> flags -> unit) -> ?dump_plugin:(unit -> unit) -> ?list_exports:(bool -> bool -> export list) -> ?default_export:(bool -> bool -> string) -> unit -> unit

Register the plugin with nbdkit​.

The ​'a parameter is the handle type returned by your ~open_connection method and passed back to all connected calls​.

val set_error : Unix.error -> unit

Set the errno returned over the NBD protocol to the client​.

Note that the NBD protocol only supports the following errno values: Unix​.EROFS , EPERM , EIO , ENOMEM , ENOSPC , ESHUTDOWN , ENOTSUP , EOVERFLOW and EINVAL ​. Any other errno will be translated to EINVAL ​.

See also nbdkit_set_error(3)

val debug : ('a, unit, string, unit) Stdlib.format4 -> 'a

Print a debug message when nbdkit is in verbose mode​.

See also nbdkit_debug(3)

val debug_hexdump : buf -> string option -> int64 -> unit

Display buffer in canonical hexdump format, sending the result to debug output (when in verbose mode)​.

See also nbdkit_debug_hexdump(3)

val debug_hexdiff : buf -> buf -> string option -> int64 -> unit

Display differences in two buffers (of equal length)​.

See also nbdkit_debug_hexdiff(3)

val timestamp : unit -> string

Generate a timestamp for log messages​.

See also nbdkit_timestamp(3)

val parse_size : string -> int64

Parse size parameter​.

Raises Invalid_argument on error​.  The actual error is sent to the nbdkit error log and is not available from the OCaml code​. It is usually best to let the exception escape​.

See also nbdkit_parse_size(3)

val parse_probability : string -> string -> float

Parse probability parameter​.

Raises Invalid_argument on error​.

See also nbdkit_parse_probability(3)

val parse_bool : string -> bool

Parse boolean parameter​.

Raises Invalid_argument on error​.

See also nbdkit_parse_bool(3)

val parse_delay : string -> string -> int * int

Parse delay parameter​.

Raises Invalid_argument on error​.

See also nbdkit_parse_delay(3)

val read_password : string -> string

Read a password​.

Raises Invalid_argument on error​.

See also nbdkit_read_password(3)

val realpath : string -> string

Returns the canonical path from a path parameter​.

See also nbdkit_realpath(3)

val stdio_safe : unit -> bool

Returns true if it is safe to interact with stdin and stdout during the configuration phase​.

See also nbdkit_stdio_safe(3)

val shutdown : unit -> unit

Requests the server shut down​.

See also nbdkit_shutdown(3)

val disconnect : bool -> unit

Requests disconnecting current client​.

See also nbdkit_disconnect(3)

val export_name : unit -> string

Returns the name of the export as requested by the client​.

See also nbdkit_export_name(3)

val is_tls : unit -> bool

Returns true if the client completed TLS authentication​.

See also nbdkit_is_tls(3)

val peer_name : unit -> Unix.sockaddr

Returns the socket address of the client​.

See also nbdkit_peer_name(3)

val peer_pid : unit -> int64

Returns the process ID of the client​.

See also nbdkit_peer_pid(3)

val peer_uid : unit -> int64

Returns the user ID of the client​.

See also nbdkit_peer_uid(3)

val peer_gid : unit -> int64

Returns the group ID of the client​.

See also nbdkit_peer_gid(3)

val peer_security_context : unit -> string

Returns the security context or label of the client​.

See also nbdkit_peer_security_context(3)

val peer_tls_dn : unit -> string

val peer_tls_issuer_dn : unit -> string

Returns the client TLS X​.509 Distinguished Name

See also nbdkit_peer_tls_dn(3)

See also nbdkit_peer_tls_issuer_dn(3)

val nanosleep : int -> int -> unit

Sleeps for seconds and nanoseconds​.

See also nbdkit_nanosleep(3)

val version : unit -> string

Returns the version of nbdkit that the plugin was compiled with​.

val api_version : unit -> int

Returns the nbdkit API version used by the plugin​.

See also The description of NBDKIT_API_VERSION in nbdkit-plugin(3)​.

val name : unit -> string option

Get the name of the nbdkit instance​.  This is the string which was set through the nbdkit --name parameter​. If the name was not set, this returns None ​.

See also nbdkit_name(3)