235 lines
7.8 KiB
Groff
235 lines
7.8 KiB
Groff
.\"
|
|
.\" Copyright (c) 2001-2003
|
|
.\" Fraunhofer Institute for Open Communication Systems (FhG Fokus).
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" Author: Hartmut Brandt <harti@freebsd.org>
|
|
.\"
|
|
.\" $Begemot: libunimsg/man/unimsg.3,v 1.2 2003/08/21 16:01:08 hbb Exp $
|
|
.\"
|
|
.Dd August 23, 2002
|
|
.Dt unimsg 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm uni_msg_len ,
|
|
.Nm uni_msg_space ,
|
|
.Nm uni_msg_leading ,
|
|
.Nm uni_msg_size ,
|
|
.Nm uni_msg_ensure ,
|
|
.Nm uni_msg_append ,
|
|
.Nm uni_msg_extend ,
|
|
.Nm uni_msg_alloc ,
|
|
.Nm uni_msg_build ,
|
|
.Nm uni_msg_destroy ,
|
|
.Nm uni_msg_strip32 ,
|
|
.Nm uni_msg_get32 ,
|
|
.Nm uni_msg_append32 ,
|
|
.Nm uni_msg_append8 ,
|
|
.Nm uni_msg_trail32 ,
|
|
.Nm uni_msg_dup
|
|
.Nd "ATM signalling library - message buffers"
|
|
.Sh LIBRARY
|
|
Begemot ATM signalling library
|
|
.Pq libunimsg, -lunimsg
|
|
.Sh SYNOPSIS
|
|
.In uni4/unimsg.h
|
|
.Ft size_t
|
|
.Fn uni_msg_len "const struct uni_msg *msg"
|
|
.Ft size_t
|
|
.Fn uni_msg_space "const struct uni_msg *msg"
|
|
.Ft size_t
|
|
.Fn uni_msg_leading "const struct uni_msg *msg"
|
|
.Ft size_t
|
|
.Fn uni_msg_size "const struct uni_msg *msg"
|
|
.Ft int
|
|
.Fn uni_msg_ensure "struct uni_msg *msg" "size_t bytes"
|
|
.Ft int
|
|
.Fn uni_msg_append "struct uni_msg *msg" "void *buf" "size_t buflen"
|
|
.Ft int
|
|
.Fn uni_msg_extend "struct uni_msg *msg" "size_t bytes"
|
|
.Ft struct uni_msg *
|
|
.Fn uni_msg_alloc "size_t space"
|
|
.Ft struct uni_msg *
|
|
.Fn uni_msg_build "void *buf" "..."
|
|
.Ft void
|
|
.Fn uni_msg_destroy "struct uni_msg *msg"
|
|
.Ft u_int
|
|
.Fn uni_msg_strip32 "struct uni_msg *msg"
|
|
.Ft u_int
|
|
.Fn uni_msg_get32 "struct uni_msg *msg"
|
|
.Ft int
|
|
.Fn uni_msg_append32 "struct uni_msg *msg" "u_int value"
|
|
.Ft int
|
|
.Fn uni_msg_append8 "struct uni_msg *msg" "u_int byte"
|
|
.Ft u_int
|
|
.Fn uni_msg_trail32 "const struct uni_msg *msg" "int n"
|
|
.Ft struct uni_msg *
|
|
.Fn uni_msg_dup "const struct uni_msg *msg"
|
|
.Sh DESCRIPTION
|
|
These functions are used to manipulate variable sized message. They are
|
|
inspired by BSD mbufs and SysV stream buffers, but somewhat simplified because
|
|
signalling generally is a low bandwidth task. All the functions operation on
|
|
a
|
|
.Li uni_msg
|
|
data structure:
|
|
.Bd -literal -offset indent
|
|
struct uni_msg {
|
|
u_char *b_wptr; /* tail pointer */
|
|
u_char *b_rptr; /* head pointer */
|
|
u_char *b_buf; /* data buffer */
|
|
u_char *b_lim; /* end of data buffer */
|
|
};
|
|
.Ed
|
|
.Pp
|
|
The field
|
|
.Fa b_buf
|
|
points to the begin of a memory block that is used to store the actual message
|
|
and the field
|
|
.Fa b_lim
|
|
points just to the first byte behind that buffer. This buffer is allocated
|
|
separate from the structure itself and the user calling any of the above
|
|
functions with a non const
|
|
.Vt struct uni_msg
|
|
argument should expect the buffer to be reallocated and hence not hold pointers
|
|
into the buffer accross call to these functions.
|
|
The pointer
|
|
.Fa b_rptr
|
|
points to the first used byte in the message and
|
|
.Fa b_wptr
|
|
to the first unused byte behind all used bytes.
|
|
If the message is empty, both pointers point to the same place somewhere in
|
|
the allocated buffer.
|
|
.Pp
|
|
There are several functions and macros that return various sizes and lengths.
|
|
The macro
|
|
.Fn uni_msg_len
|
|
returns the actual size of the message (the number of used bytes). The
|
|
macro
|
|
.Fn uni_msg_space
|
|
returns the number of bytes that are left unused behind the used space.
|
|
The macro
|
|
.Fn uni_msg_leading
|
|
returns the number of bytes that are unused before the used space and the
|
|
macro
|
|
.Fn uni_msg_size
|
|
returns the maximum size of the message (that is the size of the allocated
|
|
buffer).
|
|
.Pp
|
|
Two functions may be used to create new messages: The function
|
|
.Fn uni_msg_alloc
|
|
allocates the message structure and a buffer to hold at least
|
|
.Ar space
|
|
bytes (In fact it allocates a couple of bytes more). If the allocation fails
|
|
NULL is returned. The pointers are setup so that there is no leading space
|
|
in the buffer.
|
|
The function
|
|
.Fn uni_msg_build
|
|
constructs a new message from a variable number of buffers. The arguments
|
|
are pairs of
|
|
.Vt void *
|
|
pointers to buffers and
|
|
.Vt size_t
|
|
buffer sizes, terminated by a NULL pointer. The function computes the total
|
|
resulting message size, allocates a message and copies all the buffers
|
|
into the message. The message is built to have no leading space. If the
|
|
allocation fails, NULL is returned.
|
|
.Pp
|
|
The function
|
|
.Fn uni_msg_destroy
|
|
deallocates the buffer pointed to by the message and the message itself.
|
|
It is save to pass a message with a NULL buffer, but not a NULL message.
|
|
.Pp
|
|
The function
|
|
.Fn uni_msg_dup
|
|
returns a copy of a message with exact the same leading space.
|
|
.Pp
|
|
A number of functions are used to add bytes to an existing message.
|
|
The function
|
|
.Fn uni_msg_extend
|
|
extends the message buffer to have space for at least
|
|
.Ar bytes
|
|
additional byte at the end. The leading space does not change. This function
|
|
may reallocate the message buffer. The function returns 0 on success and ENOMEM
|
|
if the reallocation fails. In this case the message buffer is not changed.
|
|
The macro
|
|
.Fn uni_msg_ensure
|
|
checks whether the message has space for additional
|
|
.Ar bytes
|
|
bytes. If not it calls
|
|
.Fn uni_msg_extend
|
|
to make the message buffer larger. The macro returns 0 on success or ENOMEM
|
|
if there is not enough space and the reallocation fails.
|
|
In this case the message buffer is not changed.
|
|
The function
|
|
.Fn uni_msg_append
|
|
appends
|
|
.Ar buflen
|
|
bytes from the buffer pointed to by
|
|
.Ar buf
|
|
to the message.
|
|
The function
|
|
.Fn uni_msg_append8
|
|
appends one byte to the message and the function
|
|
.Fn uni_msg_append32
|
|
appends a 32-bit value in network byte order to the message (
|
|
.Fa b_wptr
|
|
needs not to be aligned). All three functions call
|
|
.Fn uni_msg_ensure
|
|
to make sure, that the buffer contents fit into the message. They
|
|
return 0 on success and ENOMEM if the buffer is too small and the reallocation
|
|
fails. In this case the message buffer is not changed.
|
|
.Pp
|
|
A number of functions can be used to retrieve parts of the message.
|
|
The function
|
|
.Fn uni_msg_strip32
|
|
returns the last four bytes of the message as a 32-bit integer assumed to
|
|
be in network byte order. It adjusts
|
|
.Fa b_wptr
|
|
to remove these four bytes from the message.
|
|
.Fa b_wptr
|
|
does not need to be aligned.
|
|
The function
|
|
.Fn uni_msg_get32
|
|
returns the first four bytes of the message as a 32-bit integer assumed to
|
|
be in network byte order. It adjusts
|
|
.Fa b_rptr
|
|
to remove these four bytes from the message.
|
|
.Fa b_rptr
|
|
does not need to be aligned.
|
|
The function
|
|
.Fn uni_msg_trail32
|
|
returns the
|
|
.Fa n 'th
|
|
32-bit integer from the buffer counted from the end of the buffer. The
|
|
integer is assumed to be in network byte order. A value of -1 for
|
|
.Fa n
|
|
returns the last four bytes of the buffer, a value of -2 the four bytes
|
|
just before the last four bytes and so on. All three functions do not check
|
|
that the message is large enough.
|
|
.Sh SEE ALSO
|
|
.Xr libunimsg 3 ,
|
|
.Xr mbuf 9
|
|
.Sh AUTHORS
|
|
.An Hartmut Brandt Aq harti@freebsd.org
|