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Files Reference
Provides access to the read/write
optical device driver.
The omd special file
provides block and character (raw) access to disks in the read/write optical
drive.
The r prefix on a
special file name means that the drive is accessed as a raw device rather than
a block device. Performing raw I/O with an optical disk requires that
all data transfers be in multiples of the optical-disk logical block
length. Also, all lseek subroutines that are made to the raw
read/write optical device driver must set the file offset pointer to a value
that is a multiple of the specified logical block size.
Read/write optical disks, used in
read/write optical drives, are media that provide storage for large amounts of
data. Block access to optical disks is achieved through the special
files /dev/omd0, /dev/omd1, ...
/dev/omdn. Character access is provided through
the special files /dev/romd0, /dev/romd1,
... /dev/romdn.
When a read/write optical disk is
ejected from the drive for a mounted read/write optical file system, the files
on the optical disk can no longer be accessed. Before attempting to
access these files again, perform the following steps for a file system
mounted from the read/write optical disk:
- Stop processes that have
files open on the file system.
- Move processes that have
current directories on the file system.
- Unmount the file
system.
- Remount the file system
after reinserting the media.
If these actions do not work,
perform a forced unmount of the file system; then, remount the file
system.
Note:
Reinserting the read/write optical disk will not fix the problem. Stop
all InfoExplorer processes (graphical and ASCII), and then forcibly unmount
the file system. Then remount the file system. After performing
this procedure, you can restart InfoExplorer and any man
commands.
Most read/write optical operations
are implemented using the open, read, write,
and close subroutines. However, for some purposes, use of
the openx (extended) subroutine is required.
The openx subroutine is
supported to provide additional functions to the open
sequence. Appropriate authority is required for execution. If an
attempt is made to run the openx subroutine without the proper
authority, the subroutine returns a value of -1 and sets the errno
global variable to a value of EPERM.
The ioctl
subroutine IOCINFO operation returns the devinfo
structure defined in the /usr/include/sys/devinfo.h
file. The IOCINFO operation is the only operation defined
for all device drivers that use the ioctl subroutine. Other
ioctl operations are specific for the type of device driver.
Diagnostic mode is not required for the IOCINFO operation.
Possible errno values
for ioctl, open, read, and write
subroutines when using the omd special file include:
| EACCES
| Indicates one of the following circumstances:
- An attempt was made to open a device currently open in
Diagnostic or Exclusive Access mode.
- An attempt was made to open a Diagnostic mode session
on a device already open.
- The user attempted a subroutine other than an
ioctl or close subroutine while in Diagnostic
mode.
- A DKIOCMD operation was attempted on a
device not in Diagnostic mode.
- A DKFORMAT operation was attempted on a
device not in Exclusive Access mode.
|
| EBUSY
| Indicates one of the following circumstances:
- The target device is reserved by another
initiator.
- An attempt was made to open a session in Exclusive
Access mode on a device already opened.
|
| EFAULT
| Indicates an illegal user address.
|
| EFORMAT
| Indicates the target device has unformatted media or media in an
incompatible format.
|
| EINVAL
| Indicates one of the following circumstances:
- The read or write subroutine
supplied an nbyte parameter that is not an even multiple of the
block size.
- A sense data buffer length of greater than 255 bytes
is not valid for a DKIOWRSE or DKIORDSE ioctl
subroutine operation.
- The data buffer length exceeded the maximum defined in
the devinfo structure for a DKIORDSE,
DKIOWRSE, or DKIOCMD ioctl subroutine operation.
- An unsupported ioctl subroutine operation
was attempted.
- An attempt was made to configure a device that is
still open.
- An illegal configuration command has been
given.
- A DKPMR (Prevent Media Removal),
DKAMR (Allow Media Removal), or DKEJECT (Eject Media)
command was sent to a device that does not support removable media.
- A DKEJECT (Eject Media) command was sent to
a device that currently has its media locked in the drive.
|
| EIO
| Indicates one of the following circumstances:
- The target device cannot be located or is not
responding.
- The target device has indicated an unrecovered
hardware error.
|
| EMEDIA
| Indicates one of the following circumstances:
- The target device has indicated an unrecovered media
error.
- The media was changed.
|
| EMFILE
| Indicates an open operation was attempted for an adapter that
already has the maximum permissible number of opened devices.
|
| ENODEV
| Indicates one of the following circumstances:
- An attempt was made to access an undefined
device.
- An attempt was made to close an undefined
device.
|
| ENOTREADY
| Indicates no read/write optical disk is in the drive.
|
| ENXIO
| Indicates one of the following circumstances:
- The ioctl subroutine supplied an invalid
parameter.
- A read or write operation was
attempted beyond the end of the physical volume.
|
| EPERM
| Indicates the attempted subroutine requires appropriate authority.
|
| ESTALE
| Indicates a read-only optical disk was ejected (without first being
closed by the user) and then either reinserted or replaced with a second
disk.
|
| ETIMEDOUT
| Indicates an I/O operation has exceeded the given timer value.
|
| EWRPROTECT
| Indicates one of the following circumstances:
- An open operation requesting
read/write mode was attempted on read-only media.
- A write operation was attempted to
read-only media.
|
The scdisk SCSI Device Driver
provides more information about implementation specifics.
The omd special file is
part of Base Operating System (BOS) Runtime.
| /dev/romd0,
/dev/romd1,...,
/dev/romdn
| Provides character access to the read/write optical device driver.
|
| /dev/omd0,
/dev/omd1,...,
/dev/omdn
| Provides block access to the read/write optical device driver.
|
Special
Files Overview.
scdisk SCSI
Device Driver.
The close subroutine, ioctl subroutine, lseek subroutine, open subroutine, read subroutine, write subroutine.
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