cgread , cgread1, cgwrite1
- read/write cylinder groups of UFS disks
LIBRARY
Lb libufs
SYNOPSIS
#include <sys/param.h>
#include <sys/mount.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/dinode.h>
#include <ufs/ffs/fs.h>
#include <libufs.h> int
cgread (struct uufsd *disk); int
cgread1 (struct uufsd *disk int c); int
cgwrite1 (struct uufsd *disk int c);
DESCRIPTION
The
cgread ();
and
cgread1 ();
functions provide cylinder group reads for
libufs(3)
consumers.
The
cgread1 ();
function reads from one cylinder group, specified by
Fa c
into the
d_cg
field of a userland UFS disk structure.
It sets the
d_lcg
field to the cylinder group number
Fa c .
The
cgread ();
function operates on sequential cylinder groups.
Calling the
cgread ();
function is equivalent to calling
cgread1 ();
with a cylinder group specifier equivalent to the value of the current
d_ccg
field, and then incrementing the
d_ccg
field.
The
cgwrite1 ();
function stores cylinder group specified by
Fa c
from
d_cg
field of a userland UFS disk structure on disk.
RETURN VALUES
Both functions return 0 if there are no more cylinder groups to read,
1 if there are more cylinder groups, and -1 on error.
ERRORS
The function
cgread ();
may fail and set
errno
for any of the errors specified for the library function
bread(3).
The function
cgread1 ();
has semantically identical failure conditions to those of
cgread (.);
The function
cgwrite1 ();
may fail and set
errno
for any of the errors specified for the library function
bwrite(3).
