1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 2001 Boris Popov 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 15.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 18.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd February 28, 2001 28.Dt MDCHAIN 9 29.Os 30.Sh NAME 31.Nm mdchain , 32.Nm md_initm , 33.Nm md_done , 34.Nm md_append_record , 35.Nm md_next_record , 36.Nm md_get_uint8 , 37.Nm md_get_uint16 , 38.Nm md_get_uint16be , 39.Nm md_get_uint16le , 40.Nm md_get_uint32 , 41.Nm md_get_uint32be , 42.Nm md_get_uint32le , 43.Nm md_get_int64 , 44.Nm md_get_int64be , 45.Nm md_get_int64le , 46.Nm md_get_mem , 47.Nm md_get_mbuf , 48.Nm md_get_uio 49.Nd "set of functions to dissect an mbuf chain to various data types" 50.Sh SYNOPSIS 51.Cd options LIBMCHAIN 52.Li kldload libmchain 53.Pp 54.Fd #include <sys/param.h> 55.Fd #include <sys/mchain.h> 56.Ft void 57.Fn md_initm "struct mdchain *mdp" "struct mbuf *m" 58.Ft void 59.Fn md_done "struct mdchain *mdp" 60.Ft void 61.Fn md_append_record "struct mdchain *mdp" "struct mbuf *top" 62.Ft int 63.Fn md_next_record "struct mdchain *mdp" 64.Ft int 65.Fn md_get_uint8 "struct mdchain *mdp" "u_int8_t x" 66.Ft int 67.Fn md_get_uint16 "struct mdchain *mdp" "u_int16_t x" 68.Ft int 69.Fn md_get_uint16be "struct mdchain *mdp" "u_int16_t x" 70.Ft int 71.Fn md_get_uint16le "struct mdchain *mdp" "u_int16_t x" 72.Ft int 73.Fn md_get_uint32 "struct mdchain *mdp" "u_int32_t x" 74.Ft int 75.Fn md_get_uint32be "struct mdchain *mdp" "u_int32_t x" 76.Ft int 77.Fn md_get_uint32le "struct mdchain *mdp" "u_int32_t x" 78.Ft int 79.Fn md_get_int64 "struct mdchain *mdp" "int64_t x" 80.Ft int 81.Fn md_get_int64be "struct mdchain *mdp" "int64_t x" 82.Ft int 83.Fn md_get_int64le "struct mdchain *mdp" "int64_t x" 84.Ft int 85.Fn md_get_mem "struct mdchain *mdp" "caddr_t target" "int size" "int type" 86.Ft int 87.Fn md_get_mbuf "struct mdchain *mdp" "struct mbuf *m" 88.Ft int 89.Fn md_get_uio "struct mdchain *mdp" "struct uio *uiop" "int size" 90.Sh DESCRIPTION 91These functions are used to decompose mbuf chains to various data types. 92The 93.Vt mdchain 94structure is used as a working context 95and should be initialized through a call of the 96.Fn mb_initm 97function. 98It has the following fields: 99.Bl -tag -width "md_top" 100.It Va "md_top" 101.Vt ( "struct mbuf *" ) 102a pointer to the top of the parsed mbuf chain 103.It Va md_cur 104.Vt ( "struct mbuf *" ) 105a pointer to the currently parsed mbuf 106.It Va md_pas 107.Vt ( int ) 108offset in the current mbuf 109.El 110.Pp 111The 112.Fn md_done 113function disposes of an mbuf chain pointed to by the 114.Fa mdp->md_top 115field and sets the field to 116.Dv NULL . 117.Pp 118The 119.Fn md_append_record 120appends a new mbuf chain using 121.Va m_nextpkt 122field to form a single linked list of mbuf chains. 123If the 124.Fa mdp->md_top 125field is 126.Dv NULL , 127then this function behaves exactly as the 128.Fn md_initm 129function. 130.Pp 131The 132.Fn md_next_record 133function extracts the next mbuf chain and disposes the current one, if any. 134For a new mbuf chain it calls the 135.Fn md_initm 136function. 137If there is no data left the function returns 138.Er ENOENT . 139.Pp 140All 141.Fn md_get_* 142functions perform an actual copy of the data from an mbuf chain. 143Functions which have 144.Cm le 145or 146.Cm be 147suffixes will perform conversion to the little\- or big\-endian data formats. 148.Pp 149.Fn md_get_mem 150function copies 151.Fa size 152bytes of data specified by the 153.Fa source 154argument from an mbuf chain. 155The 156.Fa type 157argument specifies the method used to perform a copy, 158and can be one of the following: 159.Bl -tag -width "MB_MINLINE" 160.It Dv MB_MSYSTEM 161Use the 162.Fn bcopy 163function. 164.It Dv MB_MUSER 165Use the 166.Xr copyin 9 167function. 168.It Dv MB_MINLINE 169Use an 170.Dq inline 171loop which does not call any function. 172.El 173.Pp 174If 175.Fa target 176is 177.Dv NULL , 178an actual copy is not performed 179and the function just skips the given number of bytes. 180.Sh RETURN VALUES 181All 182.Ft int 183functions return zero if successful, 184otherwise an error code is returned. 185.Pp 186.Em Note : 187after failure of any function, 188an mbuf chain is left in the broken state and only the 189.Fn md_done 190function can safely be called to destroy it. 191.Sh EXAMPLES 192.Bd -literal 193struct mdchain *mdp; 194struct mbuf *m; 195u_int16_t length; 196u_int8_t byte; 197 198receive(so, &m); 199md_initm(mdp, m); 200if (md_get_uint8(mdp, &byte) != 0 || 201 md_get_uint16le(mdp, &length) != 0) 202 error = EBADRPC; 203mb_done(mdp); 204.Ed 205.Sh SEE ALSO 206.Xr mbchain 9 , 207.Xr mbuf 9 208.Sh AUTHORS 209This manual page was written by 210.An Boris Popov Aq bp@FreeBSD.org . 211