123 lines
3.2 KiB
Groff
123 lines
3.2 KiB
Groff
.\"
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.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 16, 2004
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.Dt G_DATA 9
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.Os
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.Sh NAME
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.Nm g_read_data ,
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.Nm g_write_data
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.Nd "read/write data from/to GEOM consumer"
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.Sh SYNOPSIS
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.In geom/geom.h
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.Ft "void *"
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.Fo g_read_data
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.Fa "struct g_consumer *cp" "off_t offset" "off_t length" "int *error"
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.Fc
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.Ft int
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.Fo g_write_data
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.Fa "struct g_consumer *cp" "off_t offset" "void *ptr" "off_t length"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn g_read_data
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function reads
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.Fa length
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bytes of data from the provider attached to consumer
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.Fa cp ,
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starting at offset
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.Fa offset .
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The buffer returned from
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.Fn g_read_data
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is allocated with
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.Fn g_malloc ,
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so it should be freed by the caller with
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.Fn g_free
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after use.
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If the operation fails, an error value will be stored in the
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.Fa error
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argument if it is not
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.Dv NULL .
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.Pp
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The
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.Fn g_write_data
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function writes
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.Fa length
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bytes of data from the buffer pointed to by
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.Fa ptr
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to the provider attached to consumer
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.Fa cp ,
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starting at offset
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.Fa offset .
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.Sh RESTRICTIONS/CONDITIONS
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The
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.Fa length
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argument
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should be a multiple of the provider's sectorsize
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and less than or equal to
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.Dv DFLTPHYS
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.Dv ( DFLTPHYS
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is defined in
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.In sys/param.h ) .
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.Pp
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The topology lock must not be held.
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.Sh RETURN VALUES
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The
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.Fn g_read_data
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function returns a pointer to a data buffer or
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.Dv NULL
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if an error occurred.
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In that case an error value is stored in the
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.Fa error
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argument unless it is
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.Dv NULL .
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.Pp
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The
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.Fn g_write_data
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function returns 0 if successful; otherwise an error code is returned.
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.Sh ERRORS
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Possible errors:
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.Bl -tag -width Er
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the consumer.
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.El
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.Sh SEE ALSO
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.Xr geom 4 ,
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.Xr DECLARE_GEOM_CLASS 9 ,
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.Xr g_access 9 ,
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.Xr g_attach 9 ,
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.Xr g_bio 9 ,
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.Xr g_consumer 9 ,
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.Xr g_event 9 ,
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.Xr g_geom 9 ,
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.Xr g_provider 9 ,
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.Xr g_provider_by_name 9 ,
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.Xr g_wither_geom 9
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.Sh AUTHORS
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.An -nosplit
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This manual page was written by
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.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .
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