dkio.4

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 4 代码 · 共 128 行

.\" SCCSID: @(#)dkio.4	2.1	3/10/87
.TH dkio 4 RISC
.SH Name
dkio \- disk interface
.SH Syntax
\fB#include <sys/fs.h>\fR
.br
\fB#include <sys/ioctl.h>\fR
.SH Description
.NXS "disk interface" "dkio file"
.NXR "dkio file" "ioctl codes"
This section describes the ioctl (input/output controller) codes for all
disk drivers.
.NXR "disk interface" "ioctl codes"
The basic ioctl (input/output controller) format is:
.sp
.br
\fB#include <sys/fs.h>\fR
.br
\fB#include <sys/ioctl.h>\fR
.br
\fBioctl\fR(\fIfildes, code, arg)\fR
.br
\fBstruct pt\fR *\fR\fIarg\fR;
.sp 
The applicable \fIcodes\fR are:
.IP DIOCGETPT 16
Indicates to the driver to store
the information in the current partition table in
the address pointed to by \fIarg\fR.
The file descriptor must be opened on the raw
partitions, \fIa\fR or \fIc\fR.
.IP
DIOCGETPT does not change the partition table,
but it does provide access to the partition table information.
.IP DIOCSETPT
Indicates to the driver to modify
the current partition table with the information
pointed to by \fIarg\fR.
.IP
The file descriptor must be opened on the raw
partitions, \fIa\fR or \fIc\fR.
.IP
If the \fIa\fR or \fIc\fR partition is not mounted,
only the partition table in the driver is modified.
This temporarily modifies the partition table of the disk.
The modifications are overwritten with the default table
when the disk is turned off and on.
.IP
If the \fIa\fR or \fIc\fR partition is mounted,
both the partition table in the driver and the partition table in
the primary superblock are modified.
This permanently modifies the partition table of the disk.
This is not recommended.
To change a partition table permanently,
use the 
.MS chpt 8
command.
.IP DIOCDGTPT
Indicates to the driver to store
the \fIdefault\fR information of the current partition table in
the address pointed to by \fIarg\fR.
The file descriptor must be opened on the raw
partitions \fIa\fR or \fIc\fR.
.IP
DIOCGETPT does not change the partition table,
but it does provide access to the partition table information.
.IP DKIOCGET
Allows the user to receive generic disk information as defined in
.PN <sys/devio.h> 
.IR struct devget .
.IP DKIOCACC
This code is defined in 
.PN <sys/bbr.h>.
It is currently unused.
.RE
.SH Restrictions
.NXR "disk interface" "restricted"
These restrictions apply when using the DIOCSETPT ioctl code:
.IP \(bu 4
You must have superuser privileges.
.IP \(bu
You cannot shrink or change the offset of a partition
with a file system mounted on it
or with an open file descriptor on the entire partition.
.IP \(bu
You cannot change the offset of the \fIa\fR partition.
.SH Examples
This example shows how to use the DIOGETPT ioctl code to
print the length and offset of the \fIa\fR partition of an RZ23 disk:
.NXR(e) "disk interface" "DIOGETPT and"
.EX 0
#include <sys/types.h>
#include <sys/param.h>
#include <sys/fs.h>
#include <sys/ioctl.h>
 
main()
{
	struct pt arg;
	int fd, i;
 
	/* Open the "a" partition of the disk you want to see */
 
	if ( (fd = open("/dev/rz0a",0)) < 0 ) {
		printf("Unable to open device\\n");
		exit(2);
	}
 
	/* Get the partition information */
 
	if ( ioctl(fd,DIOCGETPT,&arg) < 0 )
		printf("Error in ioctl\\n");
 
	printf("Length\\t\\tOffset\\n");
 
 
	for ( i = 0; i <= 7; i++ ) {
		printf("%d\\t\\t%d\\n",arg.pt_part[i].pi_nblocks,
				  arg.pt_part[i].pi_blkoff );
	}
}
.SH Files
.PN /dev/{r}rz???
.SH See Also
rz(4), disktab(5), fstab(5), chpt(8), 
diskpart(8), fsck(8), MAKEDEV(8), mkfs(8), tunefs(8)