1.\" 2.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> 3.\" All rights reserved. 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 January 16, 2004 28.Dt G_DATA 9 29.Os 30.Sh NAME 31.Nm g_read_data , 32.Nm g_write_data 33.Nd "read/write data from/to GEOM consumer" 34.Sh SYNOPSIS 35.In geom/geom.h 36.Ft "void *" 37.Fo g_read_data 38.Fa "struct g_consumer *cp" "off_t offset" "off_t length" "int *error" 39.Fc 40.Ft int 41.Fo g_write_data 42.Fa "struct g_consumer *cp" "off_t offset" "void *ptr" "off_t length" 43.Fc 44.Sh DESCRIPTION 45The 46.Fn g_read_data 47function reads 48.Fa length 49bytes of data from the provider attached to consumer 50.Fa cp , 51starting at offset 52.Fa offset . 53The buffer returned from 54.Fn g_read_data 55is allocated with 56.Fn g_malloc , 57so it should be freed by the caller with 58.Fn g_free 59after use. 60If the operation fails, an error value will be stored in the 61.Fa error 62argument if it is not 63.Dv NULL . 64.Pp 65The 66.Fn g_write_data 67function writes 68.Fa length 69bytes of data from the buffer pointed to by 70.Fa ptr 71to the provider attached to consumer 72.Fa cp , 73starting at offset 74.Fa offset . 75.Sh RESTRICTIONS/CONDITIONS 76The 77.Fa length 78argument 79should be a multiple of the provider's sectorsize 80and less than or equal to 81.Dv DFLTPHYS 82.Dv ( DFLTPHYS 83is defined in 84.In sys/param.h ) . 85.Pp 86The topology lock must not be held. 87.Sh RETURN VALUES 88The 89.Fn g_read_data 90function returns a pointer to a data buffer or 91.Dv NULL 92if an error occurred. 93In that case an error value is stored in the 94.Fa error 95argument unless it is 96.Dv NULL . 97.Pp 98The 99.Fn g_write_data 100function returns 0 if successful; otherwise an error code is returned. 101.Sh ERRORS 102Possible errors: 103.Bl -tag -width Er 104.It Bq Er EIO 105Cannot read data. 106.El 107.Sh SEE ALSO 108.Xr geom 4 , 109.Xr DECLARE_GEOM_CLASS 9 , 110.Xr g_access 9 , 111.Xr g_attach 9 , 112.Xr g_bio 9 , 113.Xr g_consumer 9 , 114.Xr g_event 9 , 115.Xr g_geom 9 , 116.Xr g_provider 9 , 117.Xr g_provider_by_name 9 , 118.Xr g_wither_geom 9 119.Sh AUTHORS 120.An -nosplit 121This manual page was written by 122.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org . 123