Summary of CDROM ioctl calls.
  		============================
  
  		Edward A. Falk <efalk@google.com>
  
  		November, 2004
  
  This document attempts to describe the ioctl(2) calls supported by
  the CDROM layer.  These are by-and-large implemented (as of Linux 2.6)
  in drivers/cdrom/cdrom.c and drivers/block/scsi_ioctl.c
  
  ioctl values are listed in <linux/cdrom.h>.  As of this writing, they
  are as follows:
  
  	CDROMPAUSE		Pause Audio Operation
  	CDROMRESUME		Resume paused Audio Operation
  	CDROMPLAYMSF		Play Audio MSF (struct cdrom_msf)
  	CDROMPLAYTRKIND		Play Audio Track/index (struct cdrom_ti)
  	CDROMREADTOCHDR		Read TOC header (struct cdrom_tochdr)
  	CDROMREADTOCENTRY	Read TOC entry (struct cdrom_tocentry)
  	CDROMSTOP		Stop the cdrom drive
  	CDROMSTART		Start the cdrom drive
  	CDROMEJECT		Ejects the cdrom media
  	CDROMVOLCTRL		Control output volume (struct cdrom_volctrl)
  	CDROMSUBCHNL		Read subchannel data (struct cdrom_subchnl)
  	CDROMREADMODE2		Read CDROM mode 2 data (2336 Bytes)
  					   (struct cdrom_read)
  	CDROMREADMODE1		Read CDROM mode 1 data (2048 Bytes)
  					   (struct cdrom_read)
  	CDROMREADAUDIO		(struct cdrom_read_audio)
  	CDROMEJECT_SW		enable(1)/disable(0) auto-ejecting
  	CDROMMULTISESSION	Obtain the start-of-last-session
  				  address of multi session disks
  				  (struct cdrom_multisession)
  	CDROM_GET_MCN		Obtain the "Universal Product Code"
  				   if available (struct cdrom_mcn)
  	CDROM_GET_UPC		Deprecated, use CDROM_GET_MCN instead.
  	CDROMRESET		hard-reset the drive
  	CDROMVOLREAD		Get the drive's volume setting
  					  (struct cdrom_volctrl)
  	CDROMREADRAW		read data in raw mode (2352 Bytes)
  					   (struct cdrom_read)
  	CDROMREADCOOKED		read data in cooked mode
  	CDROMSEEK		seek msf address
  	CDROMPLAYBLK		scsi-cd only, (struct cdrom_blk)
  	CDROMREADALL		read all 2646 bytes
  	CDROMGETSPINDOWN	return 4-bit spindown value
  	CDROMSETSPINDOWN	set 4-bit spindown value
  	CDROMCLOSETRAY		pendant of CDROMEJECT
  	CDROM_SET_OPTIONS	Set behavior options
  	CDROM_CLEAR_OPTIONS	Clear behavior options
  	CDROM_SELECT_SPEED	Set the CD-ROM speed
  	CDROM_SELECT_DISC	Select disc (for juke-boxes)
  	CDROM_MEDIA_CHANGED	Check is media changed
  	CDROM_DRIVE_STATUS	Get tray position, etc.
  	CDROM_DISC_STATUS	Get disc type, etc.
  	CDROM_CHANGER_NSLOTS	Get number of slots
  	CDROM_LOCKDOOR		lock or unlock door
  	CDROM_DEBUG		Turn debug messages on/off
  	CDROM_GET_CAPABILITY	get capabilities
  	CDROMAUDIOBUFSIZ	set the audio buffer size
  	DVD_READ_STRUCT		Read structure
  	DVD_WRITE_STRUCT	Write structure
  	DVD_AUTH		Authentication
  	CDROM_SEND_PACKET	send a packet to the drive
  	CDROM_NEXT_WRITABLE	get next writable block
  	CDROM_LAST_WRITTEN	get last block written on disc
  
  
  The information that follows was determined from reading kernel source
  code.  It is likely that some corrections will be made over time.
  
  
  
  
  
  
  
  General:
  
  	Unless otherwise specified, all ioctl calls return 0 on success
  	and -1 with errno set to an appropriate value on error.  (Some
  	ioctls return non-negative data values.)
  
  	Unless otherwise specified, all ioctl calls return -1 and set
  	errno to EFAULT on a failed attempt to copy data to or from user
  	address space.
  
  	Individual drivers may return error codes not listed here.
  
  	Unless otherwise specified, all data structures and constants
  	are defined in <linux/cdrom.h>
  
  
  
  
  CDROMPAUSE			Pause Audio Operation
  
  	usage:
  
  	  ioctl(fd, CDROMPAUSE, 0);
  
  	inputs:		none
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  
  CDROMRESUME			Resume paused Audio Operation
  
  	usage:
  
  	  ioctl(fd, CDROMRESUME, 0);
  
  	inputs:		none
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  
  CDROMPLAYMSF			Play Audio MSF (struct cdrom_msf)
  
  	usage:
  
  	  struct cdrom_msf msf;
  	  ioctl(fd, CDROMPLAYMSF, &msf);
  
  	inputs:
  	  cdrom_msf structure, describing a segment of music to play
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  	notes:
  	  MSF stands for minutes-seconds-frames
  	  LBA stands for logical block address
  
  	  Segment is described as start and end times, where each time
  	  is described as minutes:seconds:frames.  A frame is 1/75 of
  	  a second.
  
  
  CDROMPLAYTRKIND			Play Audio Track/index (struct cdrom_ti)
  
  	usage:
  
  	  struct cdrom_ti ti;
  	  ioctl(fd, CDROMPLAYTRKIND, &ti);
  
  	inputs:
  	  cdrom_ti structure, describing a segment of music to play
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  	notes:
  	  Segment is described as start and end times, where each time
  	  is described as a track and an index.
  
  
  
  CDROMREADTOCHDR			Read TOC header (struct cdrom_tochdr)
  
  	usage:
  
  	  cdrom_tochdr header;
  	  ioctl(fd, CDROMREADTOCHDR, &header);
  
  	inputs:
  	  cdrom_tochdr structure
  
  	outputs:
  	  cdrom_tochdr structure
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  
  
  CDROMREADTOCENTRY		Read TOC entry (struct cdrom_tocentry)
  
  	usage:
  
  	  struct cdrom_tocentry entry;
  	  ioctl(fd, CDROMREADTOCENTRY, &entry);
  
  	inputs:
  	  cdrom_tocentry structure
  
  	outputs:
  	  cdrom_tocentry structure
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  	  EINVAL	entry.cdte_format not CDROM_MSF or CDROM_LBA
  	  EINVAL	requested track out of bounds
  	  EIO		I/O error reading TOC
  
  	notes:
  	  TOC stands for Table Of Contents
  	  MSF stands for minutes-seconds-frames
  	  LBA stands for logical block address
  
  
  
  CDROMSTOP			Stop the cdrom drive
  
  	usage:
  
  	  ioctl(fd, CDROMSTOP, 0);
  
  	inputs:		none
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  	notes:
  	  Exact interpretation of this ioctl depends on the device,
  	  but most seem to spin the drive down.
  
  
  CDROMSTART			Start the cdrom drive
  
  	usage:
  
  	  ioctl(fd, CDROMSTART, 0);
  
  	inputs:		none
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  	notes:
  	  Exact interpretation of this ioctl depends on the device,
  	  but most seem to spin the drive up and/or close the tray.
  	  Other devices ignore the ioctl completely.
  
  
  CDROMEJECT			Ejects the cdrom media
  
  	usage:
  
  	  ioctl(fd, CDROMEJECT, 0);
  
  	inputs:		none
  
  	outputs:	none
  
  	error returns:
  	  ENOSYS	cd drive not capable of ejecting
  	  EBUSY		other processes are accessing drive, or door is locked
  
  	notes:
  	  See CDROM_LOCKDOOR, below.
  
  
  
  CDROMCLOSETRAY			pendant of CDROMEJECT
  
  	usage:

  	  ioctl(fd, CDROMCLOSETRAY, 0);

  
  	inputs:		none
  
  	outputs:	none
  
  	error returns:

  	  ENOSYS	cd drive not capable of closing the tray

  	  EBUSY		other processes are accessing drive, or door is locked
  
  	notes:
  	  See CDROM_LOCKDOOR, below.
  
  
  
  CDROMVOLCTRL			Control output volume (struct cdrom_volctrl)
  
  	usage:
  
  	  struct cdrom_volctrl volume;
  	  ioctl(fd, CDROMVOLCTRL, &volume);
  
  	inputs:
  	  cdrom_volctrl structure containing volumes for up to 4
  	  channels.
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  
  
  CDROMVOLREAD			Get the drive's volume setting
  					  (struct cdrom_volctrl)
  
  	usage:
  
  	  struct cdrom_volctrl volume;
  	  ioctl(fd, CDROMVOLREAD, &volume);
  
  	inputs:		none
  
  	outputs:
  	  The current volume settings.
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  
  
  
  CDROMSUBCHNL			Read subchannel data (struct cdrom_subchnl)
  
  	usage:
  
  	  struct cdrom_subchnl q;
  	  ioctl(fd, CDROMSUBCHNL, &q);
  
  	inputs:
  	  cdrom_subchnl structure
  
  	outputs:
  	  cdrom_subchnl structure
  
  	error return:
  	  ENOSYS	cd drive not audio-capable.
  	  EINVAL	format not CDROM_MSF or CDROM_LBA
  
  	notes:

  	  Format is converted to CDROM_MSF or CDROM_LBA
  	  as per user request on return

  
  
  
  CDROMREADRAW			read data in raw mode (2352 Bytes)
  					   (struct cdrom_read)
  
  	usage:
  
  	  union {
  	    struct cdrom_msf msf;		/* input */
  	    char buffer[CD_FRAMESIZE_RAW];	/* return */
  	  } arg;
  	  ioctl(fd, CDROMREADRAW, &arg);
  
  	inputs:
  	  cdrom_msf structure indicating an address to read.
  	  Only the start values are significant.
  
  	outputs:
  	  Data written to address provided by user.
  
  	error return:
  	  EINVAL	address less than 0, or msf less than 0:2:0
  	  ENOMEM	out of memory
  
  	notes:
  	  As of 2.6.8.1, comments in <linux/cdrom.h> indicate that this
  	  ioctl accepts a cdrom_read structure, but actual source code
  	  reads a cdrom_msf structure and writes a buffer of data to
  	  the same address.
  
  	  MSF values are converted to LBA values via this formula:
  
  	    lba = (((m * CD_SECS) + s) * CD_FRAMES + f) - CD_MSF_OFFSET;
  
  
  
  
  CDROMREADMODE1			Read CDROM mode 1 data (2048 Bytes)
  					   (struct cdrom_read)
  
  	notes:
  	  Identical to CDROMREADRAW except that block size is
  	  CD_FRAMESIZE (2048) bytes
  
  
  
  CDROMREADMODE2			Read CDROM mode 2 data (2336 Bytes)
  					   (struct cdrom_read)
  
  	notes:
  	  Identical to CDROMREADRAW except that block size is
  	  CD_FRAMESIZE_RAW0 (2336) bytes
  
  
  
  CDROMREADAUDIO			(struct cdrom_read_audio)
  
  	usage:
  
  	  struct cdrom_read_audio ra;
  	  ioctl(fd, CDROMREADAUDIO, &ra);
  
  	inputs:
  	  cdrom_read_audio structure containing read start
  	  point and length
  
  	outputs:
  	  audio data, returned to buffer indicated by ra
  
  	error return:
  	  EINVAL	format not CDROM_MSF or CDROM_LBA
  	  EINVAL	nframes not in range [1 75]
  	  ENXIO		drive has no queue (probably means invalid fd)
  	  ENOMEM	out of memory
  
  
  CDROMEJECT_SW			enable(1)/disable(0) auto-ejecting
  
  	usage:
  
  	  int val;
  	  ioctl(fd, CDROMEJECT_SW, val);
  
  	inputs:
  	  Flag specifying auto-eject flag.
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	Drive is not capable of ejecting.
  	  EBUSY		Door is locked
  
  
  
  
  CDROMMULTISESSION		Obtain the start-of-last-session
  				  address of multi session disks
  				  (struct cdrom_multisession)
  	usage:
  
  	  struct cdrom_multisession ms_info;
  	  ioctl(fd, CDROMMULTISESSION, &ms_info);
  
  	inputs:
  	  cdrom_multisession structure containing desired
  	  format.
  
  	outputs:
  	  cdrom_multisession structure is filled with last_session
  	  information.
  
  	error return:
  	  EINVAL	format not CDROM_MSF or CDROM_LBA
  
  
  CDROM_GET_MCN			Obtain the "Universal Product Code"
  				   if available (struct cdrom_mcn)
  
  	usage:
  
  	  struct cdrom_mcn mcn;
  	  ioctl(fd, CDROM_GET_MCN, &mcn);
  
  	inputs:		none
  
  	outputs:
  	  Universal Product Code
  
  	error return:
  	  ENOSYS	Drive is not capable of reading MCN data.
  
  	notes:
  	  Source code comments state:
  
  	    The following function is implemented, although very few
  	    audio discs give Universal Product Code information, which
  	    should just be the Medium Catalog Number on the box.  Note,
  	    that the way the code is written on the CD is /not/ uniform
  	    across all discs!
  
  
  
  
  CDROM_GET_UPC			CDROM_GET_MCN  (deprecated)
  
  	Not implemented, as of 2.6.8.1
  
  
  
  CDROMRESET			hard-reset the drive
  
  	usage:
  
  	  ioctl(fd, CDROMRESET, 0);
  
  	inputs:		none
  
  	outputs:	none
  
  	error return:
  	  EACCES	Access denied:  requires CAP_SYS_ADMIN
  	  ENOSYS	Drive is not capable of resetting.
  
  
  
  
  CDROMREADCOOKED			read data in cooked mode
  
  	usage:
  
  	  u8 buffer[CD_FRAMESIZE]
  	  ioctl(fd, CDROMREADCOOKED, buffer);
  
  	inputs:		none
  
  	outputs:
  	  2048 bytes of data, "cooked" mode.
  
  	notes:
  	  Not implemented on all drives.
  
  
  
  
  CDROMREADALL			read all 2646 bytes
  
  	Same as CDROMREADCOOKED, but reads 2646 bytes.
  
  
  
  CDROMSEEK			seek msf address
  
  	usage:
  
  	  struct cdrom_msf msf;
  	  ioctl(fd, CDROMSEEK, &msf);
  
  	inputs:
  	  MSF address to seek to.
  
  	outputs:	none
  
  
  
  CDROMPLAYBLK			scsi-cd only, (struct cdrom_blk)
  
  	usage:
  
  	  struct cdrom_blk blk;
  	  ioctl(fd, CDROMPLAYBLK, &blk);
  
  	inputs:
  	  Region to play
  
  	outputs:	none
  
  
  
  CDROMGETSPINDOWN
  
  	usage:
  
  	  char spindown;
  	  ioctl(fd, CDROMGETSPINDOWN, &spindown);
  
  	inputs:		none
  
  	outputs:
  	  The value of the current 4-bit spindown value.
  
  
  
  
  CDROMSETSPINDOWN
  
  	usage:
  
  	  char spindown
  	  ioctl(fd, CDROMSETSPINDOWN, &spindown);
  
  	inputs:
  	  4-bit value used to control spindown (TODO: more detail here)
  
  	outputs:	none
  
  
  
  
  
  CDROM_SET_OPTIONS		Set behavior options
  
  	usage:
  
  	  int options;
  	  ioctl(fd, CDROM_SET_OPTIONS, options);
  
  	inputs:
  	  New values for drive options.  The logical 'or' of:
  	    CDO_AUTO_CLOSE	close tray on first open(2)
  	    CDO_AUTO_EJECT	open tray on last release
  	    CDO_USE_FFLAGS	use O_NONBLOCK information on open
  	    CDO_LOCK		lock tray on open files
  	    CDO_CHECK_TYPE	check type on open for data
  
  	outputs:
  	  Returns the resulting options settings in the
  	  ioctl return value.  Returns -1 on error.
  
  	error return:
  	  ENOSYS	selected option(s) not supported by drive.
  
  
  
  
  CDROM_CLEAR_OPTIONS		Clear behavior options
  
  	Same as CDROM_SET_OPTIONS, except that selected options are
  	turned off.
  
  
  
  CDROM_SELECT_SPEED		Set the CD-ROM speed
  
  	usage:
  
  	  int speed;
  	  ioctl(fd, CDROM_SELECT_SPEED, speed);
  
  	inputs:
  	  New drive speed.
  
  	outputs:	none
  
  	error return:
  	  ENOSYS	speed selection not supported by drive.
  
  
  
  CDROM_SELECT_DISC		Select disc (for juke-boxes)
  
  	usage:
  
  	  int disk;
  	  ioctl(fd, CDROM_SELECT_DISC, disk);
  
  	inputs:
  	  Disk to load into drive.
  
  	outputs:	none
  
  	error return:
  	  EINVAL	Disk number beyond capacity of drive
  
  
  
  CDROM_MEDIA_CHANGED		Check is media changed
  
  	usage:
  
  	  int slot;
  	  ioctl(fd, CDROM_MEDIA_CHANGED, slot);
  
  	inputs:
  	  Slot number to be tested, always zero except for jukeboxes.
  	  May also be special values CDSL_NONE or CDSL_CURRENT
  
  	outputs:
  	  Ioctl return value is 0 or 1 depending on whether the media
  	  has been changed, or -1 on error.
  
  	error returns:
  	  ENOSYS	Drive can't detect media change
  	  EINVAL	Slot number beyond capacity of drive
  	  ENOMEM	Out of memory
  
  
  
  CDROM_DRIVE_STATUS		Get tray position, etc.
  
  	usage:
  
  	  int slot;
  	  ioctl(fd, CDROM_DRIVE_STATUS, slot);
  
  	inputs:
  	  Slot number to be tested, always zero except for jukeboxes.
  	  May also be special values CDSL_NONE or CDSL_CURRENT
  
  	outputs:
  	  Ioctl return value will be one of the following values
  	  from <linux/cdrom.h>:
  
  	    CDS_NO_INFO		Information not available.
  	    CDS_NO_DISC
  	    CDS_TRAY_OPEN
  	    CDS_DRIVE_NOT_READY
  	    CDS_DISC_OK
  	    -1			error
  
  	error returns:
  	  ENOSYS	Drive can't detect drive status
  	  EINVAL	Slot number beyond capacity of drive
  	  ENOMEM	Out of memory
  
  
  
  
  CDROM_DISC_STATUS		Get disc type, etc.
  
  	usage:
  
  	  ioctl(fd, CDROM_DISC_STATUS, 0);
  
  	inputs:		none
  
  	outputs:
  	  Ioctl return value will be one of the following values
  	  from <linux/cdrom.h>:
  	    CDS_NO_INFO
  	    CDS_AUDIO
  	    CDS_MIXED
  	    CDS_XA_2_2
  	    CDS_XA_2_1
  	    CDS_DATA_1
  
  	error returns:	none at present
  
  	notes:
  	  Source code comments state:
  
  	    Ok, this is where problems start.  The current interface for
  	    the CDROM_DISC_STATUS ioctl is flawed.  It makes the false
  	    assumption that CDs are all CDS_DATA_1 or all CDS_AUDIO, etc.

  	    Unfortunately, while this is often the case, it is also

  	    very common for CDs to have some tracks with data, and some
  	    tracks with audio.	Just because I feel like it, I declare
  	    the following to be the best way to cope.  If the CD has
  	    ANY data tracks on it, it will be returned as a data CD.
  	    If it has any XA tracks, I will return it as that.	Now I
  	    could simplify this interface by combining these returns with
  	    the above, but this more clearly demonstrates the problem
  	    with the current interface.  Too bad this wasn't designed
  	    to use bitmasks...	       -Erik
  
  	    Well, now we have the option CDS_MIXED: a mixed-type CD.
  	    User level programmers might feel the ioctl is not very
  	    useful.
  			---david
  
  
  
  
  CDROM_CHANGER_NSLOTS		Get number of slots
  
  	usage:
  
  	  ioctl(fd, CDROM_CHANGER_NSLOTS, 0);
  
  	inputs:		none
  
  	outputs:
  	  The ioctl return value will be the number of slots in a
  	  CD changer.  Typically 1 for non-multi-disk devices.
  
  	error returns:	none
  
  
  
  CDROM_LOCKDOOR			lock or unlock door
  
  	usage:
  
  	  int lock;
  	  ioctl(fd, CDROM_LOCKDOOR, lock);
  
  	inputs:
  	  Door lock flag, 1=lock, 0=unlock
  
  	outputs:	none
  
  	error returns:
  	  EDRIVE_CANT_DO_THIS	Door lock function not supported.
  	  EBUSY			Attempt to unlock when multiple users
  	  			have the drive open and not CAP_SYS_ADMIN
  
  	notes:
  	  As of 2.6.8.1, the lock flag is a global lock, meaning that
  	  all CD drives will be locked or unlocked together.  This is
  	  probably a bug.
  
  	  The EDRIVE_CANT_DO_THIS value is defined in <linux/cdrom.h>
  	  and is currently (2.6.8.1) the same as EOPNOTSUPP
  
  
  
  CDROM_DEBUG			Turn debug messages on/off
  
  	usage:
  
  	  int debug;
  	  ioctl(fd, CDROM_DEBUG, debug);
  
  	inputs:
  	  Cdrom debug flag, 0=disable, 1=enable
  
  	outputs:
  	  The ioctl return value will be the new debug flag.
  
  	error return:
  	  EACCES	Access denied:  requires CAP_SYS_ADMIN
  
  
  
  CDROM_GET_CAPABILITY		get capabilities
  
  	usage:
  
  	  ioctl(fd, CDROM_GET_CAPABILITY, 0);
  
  	inputs:		none
  
  	outputs:
  	  The ioctl return value is the current device capability
  	  flags.  See CDC_CLOSE_TRAY, CDC_OPEN_TRAY, etc.
  
  
  
  CDROMAUDIOBUFSIZ		set the audio buffer size
  
  	usage:
  
  	  int arg;
  	  ioctl(fd, CDROMAUDIOBUFSIZ, val);
  
  	inputs:
  	  New audio buffer size
  
  	outputs:
  	  The ioctl return value is the new audio buffer size, or -1
  	  on error.
  
  	error return:
  	  ENOSYS	Not supported by this driver.
  
  	notes:
  	  Not supported by all drivers.
  
  
  
  DVD_READ_STRUCT			Read structure
  
  	usage:
  
  	  dvd_struct s;
  	  ioctl(fd, DVD_READ_STRUCT, &s);
  
  	inputs:
  	  dvd_struct structure, containing:
  	    type		specifies the information desired, one of
  	    			DVD_STRUCT_PHYSICAL, DVD_STRUCT_COPYRIGHT,
  				DVD_STRUCT_DISCKEY, DVD_STRUCT_BCA,
  				DVD_STRUCT_MANUFACT
  	    physical.layer_num	desired layer, indexed from 0
  	    copyright.layer_num	desired layer, indexed from 0
  	    disckey.agid
  
  	outputs:
  	  dvd_struct structure, containing:
  	    physical		for type == DVD_STRUCT_PHYSICAL
  	    copyright		for type == DVD_STRUCT_COPYRIGHT
  	    disckey.value	for type == DVD_STRUCT_DISCKEY
  	    bca.{len,value}	for type == DVD_STRUCT_BCA
  	    manufact.{len,valu}	for type == DVD_STRUCT_MANUFACT
  
  	error returns:
  	  EINVAL	physical.layer_num exceeds number of layers

  	  EIO		Received invalid response from drive

  
  
  
  DVD_WRITE_STRUCT		Write structure
  
  	Not implemented, as of 2.6.8.1
  
  
  
  DVD_AUTH			Authentication
  
  	usage:
  
  	  dvd_authinfo ai;
  	  ioctl(fd, DVD_AUTH, &ai);
  
  	inputs:
  	  dvd_authinfo structure.  See <linux/cdrom.h>
  
  	outputs:
  	  dvd_authinfo structure.
  
  	error return:
  	  ENOTTY	ai.type not recognized.
  
  
  
  CDROM_SEND_PACKET		send a packet to the drive
  
  	usage:
  
  	  struct cdrom_generic_command cgc;
  	  ioctl(fd, CDROM_SEND_PACKET, &cgc);
  
  	inputs:
  	  cdrom_generic_command structure containing the packet to send.
  
  	outputs:	none
  	  cdrom_generic_command structure containing results.
  
  	error return:
  	  EIO		command failed.
  	  EPERM		Operation not permitted, either because a
  			write command was attempted on a drive which
  			is opened read-only, or because the command
  			requires CAP_SYS_RAWIO
  	  EINVAL	cgc.data_direction not set
  
  
  
  CDROM_NEXT_WRITABLE		get next writable block
  
  	usage:
  
  	  long next;
  	  ioctl(fd, CDROM_NEXT_WRITABLE, &next);
  
  	inputs:		none
  
  	outputs:
  	  The next writable block.
  
  	notes:
  	  If the device does not support this ioctl directly, the
  	  ioctl will return CDROM_LAST_WRITTEN + 7.
  
  
  
  CDROM_LAST_WRITTEN		get last block written on disc
  
  	usage:
  
  	  long last;
  	  ioctl(fd, CDROM_LAST_WRITTEN, &last);
  
  	inputs:		none
  
  	outputs:
  	  The last block written on disc
  
  	notes:
  	  If the device does not support this ioctl directly, the
  	  result is derived from the disc's table of contents.  If the
  	  table of contents can't be read, this ioctl returns an
  	  error.