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