Summary of CDROM ioctl calls.
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============================
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Edward A. Falk <efalk@google.com>
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November, 2004
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This document attempts to describe the ioctl(2) calls supported by
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the CDROM layer. These are by-and-large implemented (as of Linux 2.6)
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in drivers/cdrom/cdrom.c and drivers/block/scsi_ioctl.c
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ioctl values are listed in <linux/cdrom.h>. As of this writing, they
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are as follows:
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CDROMPAUSE Pause Audio Operation
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CDROMRESUME Resume paused Audio Operation
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CDROMPLAYMSF Play Audio MSF (struct cdrom_msf)
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CDROMPLAYTRKIND Play Audio Track/index (struct cdrom_ti)
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CDROMREADTOCHDR Read TOC header (struct cdrom_tochdr)
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CDROMREADTOCENTRY Read TOC entry (struct cdrom_tocentry)
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CDROMSTOP Stop the cdrom drive
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CDROMSTART Start the cdrom drive
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CDROMEJECT Ejects the cdrom media
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CDROMVOLCTRL Control output volume (struct cdrom_volctrl)
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CDROMSUBCHNL Read subchannel data (struct cdrom_subchnl)
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CDROMREADMODE2 Read CDROM mode 2 data (2336 Bytes)
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(struct cdrom_read)
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CDROMREADMODE1 Read CDROM mode 1 data (2048 Bytes)
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(struct cdrom_read)
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CDROMREADAUDIO (struct cdrom_read_audio)
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CDROMEJECT_SW enable(1)/disable(0) auto-ejecting
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CDROMMULTISESSION Obtain the start-of-last-session
|
address of multi session disks
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(struct cdrom_multisession)
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CDROM_GET_MCN Obtain the "Universal Product Code"
|
if available (struct cdrom_mcn)
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CDROM_GET_UPC Deprecated, use CDROM_GET_MCN instead.
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CDROMRESET hard-reset the drive
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CDROMVOLREAD Get the drive's volume setting
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(struct cdrom_volctrl)
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CDROMREADRAW read data in raw mode (2352 Bytes)
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(struct cdrom_read)
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CDROMREADCOOKED read data in cooked mode
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CDROMSEEK seek msf address
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CDROMPLAYBLK scsi-cd only, (struct cdrom_blk)
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CDROMREADALL read all 2646 bytes
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CDROMGETSPINDOWN return 4-bit spindown value
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CDROMSETSPINDOWN set 4-bit spindown value
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CDROMCLOSETRAY pendant of CDROMEJECT
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CDROM_SET_OPTIONS Set behavior options
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CDROM_CLEAR_OPTIONS Clear behavior options
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CDROM_SELECT_SPEED Set the CD-ROM speed
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CDROM_SELECT_DISC Select disc (for juke-boxes)
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CDROM_MEDIA_CHANGED Check is media changed
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CDROM_DRIVE_STATUS Get tray position, etc.
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CDROM_DISC_STATUS Get disc type, etc.
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CDROM_CHANGER_NSLOTS Get number of slots
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CDROM_LOCKDOOR lock or unlock door
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CDROM_DEBUG Turn debug messages on/off
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CDROM_GET_CAPABILITY get capabilities
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CDROMAUDIOBUFSIZ set the audio buffer size
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DVD_READ_STRUCT Read structure
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DVD_WRITE_STRUCT Write structure
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DVD_AUTH Authentication
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CDROM_SEND_PACKET send a packet to the drive
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CDROM_NEXT_WRITABLE get next writable block
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CDROM_LAST_WRITTEN get last block written on disc
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The information that follows was determined from reading kernel source
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code. It is likely that some corrections will be made over time.
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General:
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Unless otherwise specified, all ioctl calls return 0 on success
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and -1 with errno set to an appropriate value on error. (Some
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ioctls return non-negative data values.)
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Unless otherwise specified, all ioctl calls return -1 and set
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errno to EFAULT on a failed attempt to copy data to or from user
|
address space.
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Individual drivers may return error codes not listed here.
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Unless otherwise specified, all data structures and constants
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are defined in <linux/cdrom.h>
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CDROMPAUSE Pause Audio Operation
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usage:
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ioctl(fd, CDROMPAUSE, 0);
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inputs: none
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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CDROMRESUME Resume paused Audio Operation
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usage:
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ioctl(fd, CDROMRESUME, 0);
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inputs: none
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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CDROMPLAYMSF Play Audio MSF (struct cdrom_msf)
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usage:
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struct cdrom_msf msf;
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ioctl(fd, CDROMPLAYMSF, &msf);
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inputs:
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cdrom_msf structure, describing a segment of music to play
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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notes:
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MSF stands for minutes-seconds-frames
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LBA stands for logical block address
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Segment is described as start and end times, where each time
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is described as minutes:seconds:frames. A frame is 1/75 of
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a second.
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CDROMPLAYTRKIND Play Audio Track/index (struct cdrom_ti)
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usage:
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struct cdrom_ti ti;
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ioctl(fd, CDROMPLAYTRKIND, &ti);
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inputs:
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cdrom_ti structure, describing a segment of music to play
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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notes:
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Segment is described as start and end times, where each time
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is described as a track and an index.
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CDROMREADTOCHDR Read TOC header (struct cdrom_tochdr)
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usage:
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cdrom_tochdr header;
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ioctl(fd, CDROMREADTOCHDR, &header);
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inputs:
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cdrom_tochdr structure
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outputs:
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cdrom_tochdr structure
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error return:
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ENOSYS cd drive not audio-capable.
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CDROMREADTOCENTRY Read TOC entry (struct cdrom_tocentry)
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usage:
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struct cdrom_tocentry entry;
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ioctl(fd, CDROMREADTOCENTRY, &entry);
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inputs:
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cdrom_tocentry structure
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outputs:
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cdrom_tocentry structure
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error return:
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ENOSYS cd drive not audio-capable.
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EINVAL entry.cdte_format not CDROM_MSF or CDROM_LBA
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EINVAL requested track out of bounds
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EIO I/O error reading TOC
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notes:
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TOC stands for Table Of Contents
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MSF stands for minutes-seconds-frames
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LBA stands for logical block address
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CDROMSTOP Stop the cdrom drive
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usage:
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ioctl(fd, CDROMSTOP, 0);
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inputs: none
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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notes:
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Exact interpretation of this ioctl depends on the device,
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but most seem to spin the drive down.
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CDROMSTART Start the cdrom drive
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usage:
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ioctl(fd, CDROMSTART, 0);
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inputs: none
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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notes:
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Exact interpretation of this ioctl depends on the device,
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but most seem to spin the drive up and/or close the tray.
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Other devices ignore the ioctl completely.
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CDROMEJECT Ejects the cdrom media
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usage:
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ioctl(fd, CDROMEJECT, 0);
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inputs: none
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outputs: none
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error returns:
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ENOSYS cd drive not capable of ejecting
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EBUSY other processes are accessing drive, or door is locked
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notes:
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See CDROM_LOCKDOOR, below.
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CDROMCLOSETRAY pendant of CDROMEJECT
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usage:
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ioctl(fd, CDROMCLOSETRAY, 0);
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inputs: none
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outputs: none
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error returns:
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ENOSYS cd drive not capable of closing the tray
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EBUSY other processes are accessing drive, or door is locked
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notes:
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See CDROM_LOCKDOOR, below.
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CDROMVOLCTRL Control output volume (struct cdrom_volctrl)
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usage:
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struct cdrom_volctrl volume;
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ioctl(fd, CDROMVOLCTRL, &volume);
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inputs:
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cdrom_volctrl structure containing volumes for up to 4
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channels.
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outputs: none
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error return:
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ENOSYS cd drive not audio-capable.
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CDROMVOLREAD Get the drive's volume setting
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(struct cdrom_volctrl)
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usage:
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struct cdrom_volctrl volume;
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ioctl(fd, CDROMVOLREAD, &volume);
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inputs: none
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outputs:
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The current volume settings.
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error return:
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ENOSYS cd drive not audio-capable.
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CDROMSUBCHNL Read subchannel data (struct cdrom_subchnl)
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usage:
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struct cdrom_subchnl q;
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ioctl(fd, CDROMSUBCHNL, &q);
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inputs:
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cdrom_subchnl structure
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outputs:
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cdrom_subchnl structure
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error return:
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ENOSYS cd drive not audio-capable.
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EINVAL format not CDROM_MSF or CDROM_LBA
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notes:
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Format is converted to CDROM_MSF or CDROM_LBA
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as per user request on return
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CDROMREADRAW read data in raw mode (2352 Bytes)
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(struct cdrom_read)
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usage:
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union {
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struct cdrom_msf msf; /* input */
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char buffer[CD_FRAMESIZE_RAW]; /* return */
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} arg;
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ioctl(fd, CDROMREADRAW, &arg);
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inputs:
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cdrom_msf structure indicating an address to read.
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Only the start values are significant.
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outputs:
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Data written to address provided by user.
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error return:
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EINVAL address less than 0, or msf less than 0:2:0
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ENOMEM out of memory
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notes:
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As of 2.6.8.1, comments in <linux/cdrom.h> indicate that this
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ioctl accepts a cdrom_read structure, but actual source code
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reads a cdrom_msf structure and writes a buffer of data to
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the same address.
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MSF values are converted to LBA values via this formula:
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lba = (((m * CD_SECS) + s) * CD_FRAMES + f) - CD_MSF_OFFSET;
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CDROMREADMODE1 Read CDROM mode 1 data (2048 Bytes)
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(struct cdrom_read)
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notes:
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Identical to CDROMREADRAW except that block size is
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CD_FRAMESIZE (2048) bytes
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CDROMREADMODE2 Read CDROM mode 2 data (2336 Bytes)
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(struct cdrom_read)
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notes:
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Identical to CDROMREADRAW except that block size is
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CD_FRAMESIZE_RAW0 (2336) bytes
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CDROMREADAUDIO (struct cdrom_read_audio)
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usage:
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struct cdrom_read_audio ra;
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ioctl(fd, CDROMREADAUDIO, &ra);
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inputs:
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cdrom_read_audio structure containing read start
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point and length
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outputs:
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audio data, returned to buffer indicated by ra
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error return:
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EINVAL format not CDROM_MSF or CDROM_LBA
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EINVAL nframes not in range [1 75]
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ENXIO drive has no queue (probably means invalid fd)
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ENOMEM out of memory
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CDROMEJECT_SW enable(1)/disable(0) auto-ejecting
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usage:
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int val;
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ioctl(fd, CDROMEJECT_SW, val);
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inputs:
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Flag specifying auto-eject flag.
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outputs: none
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error return:
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ENOSYS Drive is not capable of ejecting.
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EBUSY Door is locked
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CDROMMULTISESSION Obtain the start-of-last-session
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address of multi session disks
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(struct cdrom_multisession)
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usage:
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struct cdrom_multisession ms_info;
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ioctl(fd, CDROMMULTISESSION, &ms_info);
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inputs:
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cdrom_multisession structure containing desired
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format.
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outputs:
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cdrom_multisession structure is filled with last_session
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information.
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error return:
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EINVAL format not CDROM_MSF or CDROM_LBA
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CDROM_GET_MCN Obtain the "Universal Product Code"
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if available (struct cdrom_mcn)
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usage:
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struct cdrom_mcn mcn;
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ioctl(fd, CDROM_GET_MCN, &mcn);
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inputs: none
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outputs:
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Universal Product Code
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error return:
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ENOSYS Drive is not capable of reading MCN data.
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notes:
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Source code comments state:
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The following function is implemented, although very few
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audio discs give Universal Product Code information, which
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should just be the Medium Catalog Number on the box. Note,
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that the way the code is written on the CD is /not/ uniform
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across all discs!
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CDROM_GET_UPC CDROM_GET_MCN (deprecated)
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Not implemented, as of 2.6.8.1
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CDROMRESET hard-reset the drive
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usage:
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ioctl(fd, CDROMRESET, 0);
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inputs: none
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outputs: none
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error return:
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EACCES Access denied: requires CAP_SYS_ADMIN
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ENOSYS Drive is not capable of resetting.
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CDROMREADCOOKED read data in cooked mode
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usage:
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u8 buffer[CD_FRAMESIZE]
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ioctl(fd, CDROMREADCOOKED, buffer);
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inputs: none
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outputs:
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2048 bytes of data, "cooked" mode.
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notes:
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Not implemented on all drives.
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CDROMREADALL read all 2646 bytes
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Same as CDROMREADCOOKED, but reads 2646 bytes.
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CDROMSEEK seek msf address
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usage:
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struct cdrom_msf msf;
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ioctl(fd, CDROMSEEK, &msf);
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inputs:
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MSF address to seek to.
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outputs: none
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CDROMPLAYBLK scsi-cd only, (struct cdrom_blk)
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usage:
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struct cdrom_blk blk;
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ioctl(fd, CDROMPLAYBLK, &blk);
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inputs:
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Region to play
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outputs: none
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CDROMGETSPINDOWN
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usage:
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char spindown;
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ioctl(fd, CDROMGETSPINDOWN, &spindown);
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inputs: none
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outputs:
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The value of the current 4-bit spindown value.
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CDROMSETSPINDOWN
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usage:
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char spindown
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ioctl(fd, CDROMSETSPINDOWN, &spindown);
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inputs:
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4-bit value used to control spindown (TODO: more detail here)
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outputs: none
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CDROM_SET_OPTIONS Set behavior options
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usage:
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int options;
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ioctl(fd, CDROM_SET_OPTIONS, options);
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inputs:
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New values for drive options. The logical 'or' of:
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CDO_AUTO_CLOSE close tray on first open(2)
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CDO_AUTO_EJECT open tray on last release
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CDO_USE_FFLAGS use O_NONBLOCK information on open
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CDO_LOCK lock tray on open files
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CDO_CHECK_TYPE check type on open for data
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outputs:
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Returns the resulting options settings in the
|
ioctl return value. Returns -1 on error.
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error return:
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ENOSYS selected option(s) not supported by drive.
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CDROM_CLEAR_OPTIONS Clear behavior options
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Same as CDROM_SET_OPTIONS, except that selected options are
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turned off.
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CDROM_SELECT_SPEED Set the CD-ROM speed
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usage:
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int speed;
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ioctl(fd, CDROM_SELECT_SPEED, speed);
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inputs:
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New drive speed.
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outputs: none
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error return:
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ENOSYS speed selection not supported by drive.
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CDROM_SELECT_DISC Select disc (for juke-boxes)
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usage:
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int disk;
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ioctl(fd, CDROM_SELECT_DISC, disk);
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inputs:
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Disk to load into drive.
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outputs: none
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error return:
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EINVAL Disk number beyond capacity of drive
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CDROM_MEDIA_CHANGED Check is media changed
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usage:
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int slot;
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ioctl(fd, CDROM_MEDIA_CHANGED, slot);
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inputs:
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Slot number to be tested, always zero except for jukeboxes.
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May also be special values CDSL_NONE or CDSL_CURRENT
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outputs:
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Ioctl return value is 0 or 1 depending on whether the media
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has been changed, or -1 on error.
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error returns:
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ENOSYS Drive can't detect media change
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EINVAL Slot number beyond capacity of drive
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ENOMEM Out of memory
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CDROM_DRIVE_STATUS Get tray position, etc.
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usage:
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int slot;
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ioctl(fd, CDROM_DRIVE_STATUS, slot);
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inputs:
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Slot number to be tested, always zero except for jukeboxes.
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May also be special values CDSL_NONE or CDSL_CURRENT
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outputs:
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Ioctl return value will be one of the following values
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from <linux/cdrom.h>:
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CDS_NO_INFO Information not available.
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CDS_NO_DISC
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CDS_TRAY_OPEN
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CDS_DRIVE_NOT_READY
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CDS_DISC_OK
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-1 error
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error returns:
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ENOSYS Drive can't detect drive status
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EINVAL Slot number beyond capacity of drive
|
ENOMEM Out of memory
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CDROM_DISC_STATUS Get disc type, etc.
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usage:
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ioctl(fd, CDROM_DISC_STATUS, 0);
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inputs: none
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outputs:
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Ioctl return value will be one of the following values
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from <linux/cdrom.h>:
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CDS_NO_INFO
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CDS_AUDIO
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CDS_MIXED
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CDS_XA_2_2
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CDS_XA_2_1
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CDS_DATA_1
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error returns: none at present
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notes:
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Source code comments state:
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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.
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Unfortunately, while this is often the case, it is also
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very common for CDs to have some tracks with data, and some
|
tracks with audio. Just because I feel like it, I declare
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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
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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
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Well, now we have the option CDS_MIXED: a mixed-type CD.
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User level programmers might feel the ioctl is not very
|
useful.
|
---david
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CDROM_CHANGER_NSLOTS Get number of slots
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usage:
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ioctl(fd, CDROM_CHANGER_NSLOTS, 0);
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inputs: none
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outputs:
|
The ioctl return value will be the number of slots in a
|
CD changer. Typically 1 for non-multi-disk devices.
|
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error returns: none
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CDROM_LOCKDOOR lock or unlock door
|
|
usage:
|
|
int lock;
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ioctl(fd, CDROM_LOCKDOOR, lock);
|
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inputs:
|
Door lock flag, 1=lock, 0=unlock
|
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outputs: none
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error returns:
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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
|
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CDROM_DEBUG Turn debug messages on/off
|
|
usage:
|
|
int debug;
|
ioctl(fd, CDROM_DEBUG, debug);
|
|
inputs:
|
Cdrom debug flag, 0=disable, 1=enable
|
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outputs:
|
The ioctl return value will be the new debug flag.
|
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error return:
|
EACCES Access denied: requires CAP_SYS_ADMIN
|
|
|
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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.
|
|
|
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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.
|
