2003-06-09 10:59:11 +01:00
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.\" Author: Juli Mallett <jmallett@FreeBSD.org>
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.\" Date: June 04, 2003
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.\" Description:
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.\" Manual page for libufs functions:
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.\" cgread(3)
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.\" cgread1(3)
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.\"
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2003-06-10 19:24:40 +01:00
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.\" This file is in the public domain.
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.\"
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2003-06-09 10:59:11 +01:00
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.\" $FreeBSD$
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.\"
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.Dd June 04, 2003
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.Dt CGREAD 3
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.Os
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.Sh NAME
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.Nm cgread , cgread1
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.Nd read cylinder groups of UFS disks
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.Sh LIBRARY
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.Lb libufs
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/mount.h
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.In ufs/ufs/ufsmount.h
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.In ufs/ufs/dinode.h
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.In ufs/ffs/fs.h
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.In libufs.h
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.Ft int
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.Fn cgread "struct uufsd *disk"
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.Ft int
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.Fn cgread1 "struct uufsd *disk" "int c"
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.Sh DESCRIPTION
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The
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.Fn cgread
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and
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.Fn cgread1
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functions provide cylinder group reads for
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.Xr libufs 3
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consumers.
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The
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.Fn cgread1
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function reads from one cylinder group, specified by
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.Fa c
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into the
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.Fa d_cg
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field of a userland UFS disk structure.
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It sets the
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.Fa d_lcg
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2003-06-10 19:36:16 +01:00
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field to the cylinder group number
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2003-06-09 10:59:11 +01:00
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.Fa c .
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.Pp
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The
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.Fn cgread
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function operates on sequential cylinder groups.
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Calling the
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.Fn cgread
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function is equivalent to calling
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.Nm cgread1
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with a cylinder group specifier equivalent to the value of the current
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.Fa d_ccg
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field, and then incrementing the
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.Fa d_ccg
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field.
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.Pp
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Both functions return 0 if there are no more cylinder groups to read,
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1 if there are more cylinder groups, and -1 on error.
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.Sh ERRORS
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The function
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.Fn cgread
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may fail and set
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.Va errno
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for any of the errors specified for the library function
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.Xr bread 3 .
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.Pp
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The function
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.Fn cgread1
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has semantically identical failure conditions to those of
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.Fn cgread .
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.Sh SEE ALSO
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.Xr bread 3 ,
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.Xr libufs 3
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.Sh HISTORY
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These functions first appeared as part of
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.Xr libufs 3
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in
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.Fx 5.1 .
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.Sh AUTHORS
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.An Juli Mallett Aq jmallett@FreeBSD.org
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