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.Dd February 28, 2001 26.Dt MDCHAIN 9 27.Os 28.Sh NAME 29.Nm mdchain , 30.Nm md_initm , 31.Nm md_done , 32.Nm md_append_record , 33.Nm md_next_record , 34.Nm md_get_uint8 , 35.Nm md_get_uint16 , 36.Nm md_get_uint16be , 37.Nm md_get_uint16le , 38.Nm md_get_uint32 , 39.Nm md_get_uint32be , 40.Nm md_get_uint32le , 41.Nm md_get_int64 , 42.Nm md_get_int64be , 43.Nm md_get_int64le , 44.Nm md_get_mem , 45.Nm md_get_mbuf , 46.Nm md_get_uio 47.Nd "set of functions to dissect an mbuf chain to various data types" 48.Sh SYNOPSIS 49.Cd options LIBMCHAIN 50.Li kldload libmchain 51.Pp 52.In sys/param.h 53.In sys/uio.h 54.In sys/mchain.h 55.Ft void 56.Fn md_initm "struct mdchain *mdp" "struct mbuf *m" 57.Ft void 58.Fn md_done "struct mdchain *mdp" 59.Ft void 60.Fn md_append_record "struct mdchain *mdp" "struct mbuf *top" 61.Ft int 62.Fn md_next_record "struct mdchain *mdp" 63.Ft int 64.Fn md_get_uint8 "struct mdchain *mdp" "uint8_t *x" 65.Ft int 66.Fn md_get_uint16 "struct mdchain *mdp" "uint16_t *x" 67.Ft int 68.Fn md_get_uint16be "struct mdchain *mdp" "uint16_t *x" 69.Ft int 70.Fn md_get_uint16le "struct mdchain *mdp" "uint16_t *x" 71.Ft int 72.Fn md_get_uint32 "struct mdchain *mdp" "uint32_t *x" 73.Ft int 74.Fn md_get_uint32be "struct mdchain *mdp" "uint32_t *x" 75.Ft int 76.Fn md_get_uint32le "struct mdchain *mdp" "uint32_t *x" 77.Ft int 78.Fn md_get_int64 "struct mdchain *mdp" "int64_t *x" 79.Ft int 80.Fn md_get_int64be "struct mdchain *mdp" "int64_t *x" 81.Ft int 82.Fn md_get_int64le "struct mdchain *mdp" "int64_t *x" 83.Ft int 84.Fn md_get_mem "struct mdchain *mdp" "caddr_t target" "int size" "int type" 85.Ft int 86.Fn md_get_mbuf "struct mdchain *mdp" "int size" "struct mbuf **m" 87.Ft int 88.Fn md_get_uio "struct mdchain *mdp" "struct uio *uiop" "int size" 89.Sh DESCRIPTION 90These functions are used to decompose mbuf chains to various data types. 91The 92.Vt mdchain 93structure is used as a working context 94and should be initialized through a call of the 95.Fn mb_initm 96function. 97It has the following fields: 98.Bl -tag -width "md_top" 99.It Va "md_top" 100.Pq Vt "struct mbuf *" 101A pointer to the top of the parsed mbuf chain. 102.It Va md_cur 103.Pq Vt "struct mbuf *" 104A pointer to the currently parsed mbuf. 105.It Va md_pas 106.Pq Vt int 107Offset in the current mbuf. 108.El 109.Pp 110The 111.Fn md_done 112function disposes of an mbuf chain pointed to by the 113.Fa mdp->md_top 114field and sets the field to 115.Dv NULL . 116.Pp 117The 118.Fn md_append_record 119appends a new mbuf chain using 120.Va m_nextpkt 121field to form a single linked list of mbuf chains. 122If the 123.Fa mdp->md_top 124field is 125.Dv NULL , 126then this function behaves exactly as the 127.Fn md_initm 128function. 129.Pp 130The 131.Fn md_next_record 132function extracts the next mbuf chain and disposes the current one, if any. 133For a new mbuf chain it calls the 134.Fn md_initm 135function. 136If there is no data left the function returns 137.Er ENOENT . 138.Pp 139All 140.Fn md_get_* 141functions perform an actual copy of the data from an mbuf chain. 142Functions which have 143.Cm le 144or 145.Cm be 146suffixes will perform conversion to the little\- or big\-endian data formats. 147.Pp 148.Fn md_get_mem 149function copies 150.Fa size 151bytes of data specified by the 152.Fa source 153argument from an mbuf chain. 154The 155.Fa type 156argument specifies the method used to perform a copy, 157and can be one of the following: 158.Bl -tag -width ".Dv MB_MINLINE" 159.It Dv MB_MSYSTEM 160Use the 161.Fn bcopy 162function. 163.It Dv MB_MUSER 164Use the 165.Xr copyin 9 166function. 167.It Dv MB_MINLINE 168Use an 169.Dq inline 170loop which does not call any function. 171.El 172.Pp 173If 174.Fa target 175is 176.Dv NULL , 177an actual copy is not performed 178and the function just skips the given number of bytes. 179.Sh RETURN VALUES 180All 181.Ft int 182functions return zero if successful, 183otherwise an error code is returned. 184.Pp 185.Em Note : 186after failure of any function, 187an mbuf chain is left in the broken state and only the 188.Fn md_done 189function can safely be called to destroy it. 190.Sh EXAMPLES 191.Bd -literal 192struct mdchain *mdp; 193struct mbuf *m; 194uint16_t length; 195uint8_t byte; 196 197receive(so, &m); 198md_initm(mdp, m); 199if (md_get_uint8(mdp, &byte) != 0 || 200 md_get_uint16le(mdp, &length) != 0) 201 error = EBADRPC; 202mb_done(mdp); 203.Ed 204.Sh SEE ALSO 205.Xr mbchain 9 , 206.Xr mbuf 9 207.Sh AUTHORS 208This manual page was written by 209.An Boris Popov Aq Mt bp@FreeBSD.org . 210