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100 lines
2.0 KiB
Groff
100 lines
2.0 KiB
Groff
.\" 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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.\" bread(3)
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.\" bwrite(3)
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.\"
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.\" This file is in the public domain.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 4, 2003
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.Dt BREAD 3
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.Os
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.Sh NAME
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.Nm bread , bwrite
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.Nd read and write blocks of a UFS file system
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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 ssize_t
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.Fn bread "struct uufsd *disk" "ufs2_daddr_t blockno" "void *data" "size_t size"
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.Ft ssize_t
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.Fo bwrite
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.Fa "struct uufsd *disk" "ufs2_daddr_t blockno"
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.Fa "const void *data" "size_t size"
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.Fc
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.Ft int
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.Fo berase
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.Fa "struct uufsd *disk" "ufs2_daddr_t blockno" "ufs2_daddr_t size"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn bread ,
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.Fn bwrite
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and
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.Fn berase
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functions provide a block read, write and erase API for
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.Xr libufs 3
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consumers.
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They operate on a userland UFS disk structure, and perform the read
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and write at a given block address, which uses the current
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.Va d_bsize
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value of the structure.
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.Sh RETURN VALUES
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The
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.Fn bread
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and
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.Fn bwrite
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functions return the amount read or written, or \-1 in case of any error,
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including short read.
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.Pp
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The
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.Fn berase
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function returns non-zero on error.
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.Sh ERRORS
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The function
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.Fn bread
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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 functions
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.Xr ufs_disk_write 3
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or
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.Xr pread 2 .
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.Pp
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The function
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.Fn bwrite
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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 pwrite 2 .
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.Pp
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The function
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.Fn berase
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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 ioctl 2 .
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.Pp
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Additionally all three functions may follow the
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.Xr libufs 3
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error methodologies in situations where the amount of data written
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is not equal to the amount requested, or in case of a device error.
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.Sh SEE ALSO
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.Xr libufs 3 ,
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.Xr ufs_disk_write 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 5.0 .
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.Sh AUTHORS
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.An Juli Mallett Aq jmallett@FreeBSD.org
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