Documentation/ioctl/cdrom.txt

   1                 Summary of CDROM ioctl calls.
   2                 ============================
   3
   4                 Edward A. Falk <efalk@google.com>
   5
   6                 November, 2004
   7
   8 This document attempts to describe the ioctl(2) calls supported by
   9 the CDROM layer.  These are by-and-large implemented (as of Linux 2.6)
  10 in drivers/cdrom/cdrom.c and drivers/block/scsi_ioctl.c
  11
  12 ioctl values are listed in <linux/cdrom.h>.  As of this writing, they
  13 are as follows:
  14
  15         CDROMPAUSE              Pause Audio Operation
  16         CDROMRESUME             Resume paused Audio Operation
  17         CDROMPLAYMSF            Play Audio MSF (struct cdrom_msf)
  18         CDROMPLAYTRKIND         Play Audio Track/index (struct cdrom_ti)
  19         CDROMREADTOCHDR         Read TOC header (struct cdrom_tochdr)
  20         CDROMREADTOCENTRY       Read TOC entry (struct cdrom_tocentry)
  21         CDROMSTOP               Stop the cdrom drive
  22         CDROMSTART              Start the cdrom drive
  23         CDROMEJECT              Ejects the cdrom media
  24         CDROMVOLCTRL            Control output volume (struct cdrom_volctrl)
  25         CDROMSUBCHNL            Read subchannel data (struct cdrom_subchnl)
  26         CDROMREADMODE2          Read CDROM mode 2 data (2336 Bytes)
  27                                            (struct cdrom_read)
  28         CDROMREADMODE1          Read CDROM mode 1 data (2048 Bytes)
  29                                            (struct cdrom_read)
  30         CDROMREADAUDIO          (struct cdrom_read_audio)
  31         CDROMEJECT_SW           enable(1)/disable(0) auto-ejecting
  32         CDROMMULTISESSION       Obtain the start-of-last-session
  33                                   address of multi session disks
  34                                   (struct cdrom_multisession)
  35         CDROM_GET_MCN           Obtain the "Universal Product Code"
  36                                    if available (struct cdrom_mcn)
  37         CDROM_GET_UPC           Deprecated, use CDROM_GET_MCN instead.
  38         CDROMRESET              hard-reset the drive
  39         CDROMVOLREAD            Get the drive's volume setting
  40                                           (struct cdrom_volctrl)
  41         CDROMREADRAW            read data in raw mode (2352 Bytes)
  42                                            (struct cdrom_read)
  43         CDROMREADCOOKED         read data in cooked mode
  44         CDROMSEEK               seek msf address
  45         CDROMPLAYBLK            scsi-cd only, (struct cdrom_blk)
  46         CDROMREADALL            read all 2646 bytes
  47         CDROMGETSPINDOWN        return 4-bit spindown value
  48         CDROMSETSPINDOWN        set 4-bit spindown value
  49         CDROMCLOSETRAY          pendant of CDROMEJECT
  50         CDROM_SET_OPTIONS       Set behavior options
  51         CDROM_CLEAR_OPTIONS     Clear behavior options
  52         CDROM_SELECT_SPEED      Set the CD-ROM speed
  53         CDROM_SELECT_DISC       Select disc (for juke-boxes)
  54         CDROM_MEDIA_CHANGED     Check is media changed
  55         CDROM_DRIVE_STATUS      Get tray position, etc.
  56         CDROM_DISC_STATUS       Get disc type, etc.
  57         CDROM_CHANGER_NSLOTS    Get number of slots
  58         CDROM_LOCKDOOR          lock or unlock door
  59         CDROM_DEBUG             Turn debug messages on/off
  60         CDROM_GET_CAPABILITY    get capabilities
  61         CDROMAUDIOBUFSIZ        set the audio buffer size
  62         DVD_READ_STRUCT         Read structure
  63         DVD_WRITE_STRUCT        Write structure
  64         DVD_AUTH                Authentication
  65         CDROM_SEND_PACKET       send a packet to the drive
  66         CDROM_NEXT_WRITABLE     get next writable block
  67         CDROM_LAST_WRITTEN      get last block written on disc
  68
  69
  70 The information that follows was determined from reading kernel source
  71 code.  It is likely that some corrections will be made over time.
  72
  73
  74
  75
  76
  77
  78
  79 General:
  80
  81         Unless otherwise specified, all ioctl calls return 0 on success
  82         and -1 with errno set to an appropriate value on error.  (Some
  83         ioctls return non-negative data values.)
  84
  85         Unless otherwise specified, all ioctl calls return -1 and set
  86         errno to EFAULT on a failed attempt to copy data to or from user
  87         address space.
  88
  89         Individual drivers may return error codes not listed here.
  90
  91         Unless otherwise specified, all data structures and constants
  92         are defined in <linux/cdrom.h>
  93
  94
  95
  96
  97 CDROMPAUSE                      Pause Audio Operation
  98
  99         usage:
 100
 101           ioctl(fd, CDROMPAUSE, 0);
 102
 103         inputs:         none
 104
 105         outputs:        none
 106
 107         error return:
 108           ENOSYS        cd drive not audio-capable.
 109
 110
 111 CDROMRESUME                     Resume paused Audio Operation
 112
 113         usage:
 114
 115           ioctl(fd, CDROMRESUME, 0);
 116
 117         inputs:         none
 118
 119         outputs:        none
 120
 121         error return:
 122           ENOSYS        cd drive not audio-capable.
 123
 124
 125 CDROMPLAYMSF                    Play Audio MSF (struct cdrom_msf)
 126
 127         usage:
 128
 129           struct cdrom_msf msf;
 130           ioctl(fd, CDROMPLAYMSF, &msf);
 131
 132         inputs:
 133           cdrom_msf structure, describing a segment of music to play
 134
 135         outputs:        none
 136
 137         error return:
 138           ENOSYS        cd drive not audio-capable.
 139
 140         notes:
 141           MSF stands for minutes-seconds-frames
 142           LBA stands for logical block address
 143
 144           Segment is described as start and end times, where each time
 145           is described as minutes:seconds:frames.  A frame is 1/75 of
 146           a second.
 147
 148
 149 CDROMPLAYTRKIND                 Play Audio Track/index (struct cdrom_ti)
 150
 151         usage:
 152
 153           struct cdrom_ti ti;
 154           ioctl(fd, CDROMPLAYTRKIND, &ti);
 155
 156         inputs:
 157           cdrom_ti structure, describing a segment of music to play
 158
 159         outputs:        none
 160
 161         error return:
 162           ENOSYS        cd drive not audio-capable.
 163
 164         notes:
 165           Segment is described as start and end times, where each time
 166           is described as a track and an index.
 167
 168
 169
 170 CDROMREADTOCHDR                 Read TOC header (struct cdrom_tochdr)
 171
 172         usage:
 173
 174           cdrom_tochdr header;
 175           ioctl(fd, CDROMREADTOCHDR, &header);
 176
 177         inputs:
 178           cdrom_tochdr structure
 179
 180         outputs:
 181           cdrom_tochdr structure
 182
 183         error return:
 184           ENOSYS        cd drive not audio-capable.
 185
 186
 187
 188 CDROMREADTOCENTRY               Read TOC entry (struct cdrom_tocentry)
 189
 190         usage:
 191
 192           struct cdrom_tocentry entry;
 193           ioctl(fd, CDROMREADTOCENTRY, &entry);
 194
 195         inputs:
 196           cdrom_tocentry structure
 197
 198         outputs:
 199           cdrom_tocentry structure
 200
 201         error return:
 202           ENOSYS        cd drive not audio-capable.
 203           EINVAL        entry.cdte_format not CDROM_MSF or CDROM_LBA
 204           EINVAL        requested track out of bounds
 205           EIO           I/O error reading TOC
 206
 207         notes:
 208           TOC stands for Table Of Contents
 209           MSF stands for minutes-seconds-frames
 210           LBA stands for logical block address
 211
 212
 213
 214 CDROMSTOP                       Stop the cdrom drive
 215
 216         usage:
 217
 218           ioctl(fd, CDROMSTOP, 0);
 219
 220         inputs:         none
 221
 222         outputs:        none
 223
 224         error return:
 225           ENOSYS        cd drive not audio-capable.
 226
 227         notes:
 228           Exact interpretation of this ioctl depends on the device,
 229           but most seem to spin the drive down.
 230
 231
 232 CDROMSTART                      Start the cdrom drive
 233
 234         usage:
 235
 236           ioctl(fd, CDROMSTART, 0);
 237
 238         inputs:         none
 239
 240         outputs:        none
 241
 242         error return:
 243           ENOSYS        cd drive not audio-capable.
 244
 245         notes:
 246           Exact interpretation of this ioctl depends on the device,
 247           but most seem to spin the drive up and/or close the tray.
 248           Other devices ignore the ioctl completely.
 249
 250
 251 CDROMEJECT                      Ejects the cdrom media
 252
 253         usage:
 254
 255           ioctl(fd, CDROMEJECT, 0);
 256
 257         inputs:         none
 258
 259         outputs:        none
 260
 261         error returns:
 262           ENOSYS        cd drive not capable of ejecting
 263           EBUSY         other processes are accessing drive, or door is locked
 264
 265         notes:
 266           See CDROM_LOCKDOOR, below.
 267
 268
 269
 270 CDROMCLOSETRAY                  pendant of CDROMEJECT
 271
 272         usage:
 273
 274           ioctl(fd, CDROMCLOSETRAY, 0);
 275
 276         inputs:         none
 277
 278         outputs:        none
 279
 280         error returns:
 281           ENOSYS        cd drive not capable of closing the tray
 282           EBUSY         other processes are accessing drive, or door is locked
 283
 284         notes:
 285           See CDROM_LOCKDOOR, below.
 286
 287
 288
 289 CDROMVOLCTRL                    Control output volume (struct cdrom_volctrl)
 290
 291         usage:
 292
 293           struct cdrom_volctrl volume;
 294           ioctl(fd, CDROMVOLCTRL, &volume);
 295
 296         inputs:
 297           cdrom_volctrl structure containing volumes for up to 4
 298           channels.
 299
 300         outputs:        none
 301
 302         error return:
 303           ENOSYS        cd drive not audio-capable.
 304
 305
 306
 307 CDROMVOLREAD                    Get the drive's volume setting
 308                                           (struct cdrom_volctrl)
 309
 310         usage:
 311
 312           struct cdrom_volctrl volume;
 313           ioctl(fd, CDROMVOLREAD, &volume);
 314
 315         inputs:         none
 316
 317         outputs:
 318           The current volume settings.
 319
 320         error return:
 321           ENOSYS        cd drive not audio-capable.
 322
 323
 324
 325 CDROMSUBCHNL                    Read subchannel data (struct cdrom_subchnl)
 326
 327         usage:
 328
 329           struct cdrom_subchnl q;
 330           ioctl(fd, CDROMSUBCHNL, &q);
 331
 332         inputs:
 333           cdrom_subchnl structure
 334
 335         outputs:
 336           cdrom_subchnl structure
 337
 338         error return:
 339           ENOSYS        cd drive not audio-capable.
 340           EINVAL        format not CDROM_MSF or CDROM_LBA
 341
 342         notes:
 343           Format is converted to CDROM_MSF or CDROM_LBA
 344           as per user request on return
 345
 346
 347
 348 CDROMREADRAW                    read data in raw mode (2352 Bytes)
 349                                            (struct cdrom_read)
 350
 351         usage:
 352
 353           union {
 354             struct cdrom_msf msf;               /* input */
 355             char buffer[CD_FRAMESIZE_RAW];      /* return */
 356           } arg;
 357           ioctl(fd, CDROMREADRAW, &arg);
 358
 359         inputs:
 360           cdrom_msf structure indicating an address to read.
 361           Only the start values are significant.
 362
 363         outputs:
 364           Data written to address provided by user.
 365
 366         error return:
 367           EINVAL        address less than 0, or msf less than 0:2:0
 368           ENOMEM        out of memory
 369
 370         notes:
 371           As of 2.6.8.1, comments in <linux/cdrom.h> indicate that this
 372           ioctl accepts a cdrom_read structure, but actual source code
 373           reads a cdrom_msf structure and writes a buffer of data to
 374           the same address.
 375
 376           MSF values are converted to LBA values via this formula:
 377
 378             lba = (((m * CD_SECS) + s) * CD_FRAMES + f) - CD_MSF_OFFSET;
 379
 380
 381
 382
 383 CDROMREADMODE1                  Read CDROM mode 1 data (2048 Bytes)
 384                                            (struct cdrom_read)
 385
 386         notes:
 387           Identical to CDROMREADRAW except that block size is
 388           CD_FRAMESIZE (2048) bytes
 389
 390
 391
 392 CDROMREADMODE2                  Read CDROM mode 2 data (2336 Bytes)
 393                                            (struct cdrom_read)
 394
 395         notes:
 396           Identical to CDROMREADRAW except that block size is
 397           CD_FRAMESIZE_RAW0 (2336) bytes
 398
 399
 400
 401 CDROMREADAUDIO                  (struct cdrom_read_audio)
 402
 403         usage:
 404
 405           struct cdrom_read_audio ra;
 406           ioctl(fd, CDROMREADAUDIO, &ra);
 407
 408         inputs:
 409           cdrom_read_audio structure containing read start
 410           point and length
 411
 412         outputs:
 413           audio data, returned to buffer indicated by ra
 414
 415         error return:
 416           EINVAL        format not CDROM_MSF or CDROM_LBA
 417           EINVAL        nframes not in range [1 75]
 418           ENXIO         drive has no queue (probably means invalid fd)
 419           ENOMEM        out of memory
 420
 421
 422 CDROMEJECT_SW                   enable(1)/disable(0) auto-ejecting
 423
 424         usage:
 425
 426           int val;
 427           ioctl(fd, CDROMEJECT_SW, val);
 428
 429         inputs:
 430           Flag specifying auto-eject flag.
 431
 432         outputs:        none
 433
 434         error return:
 435           ENOSYS        Drive is not capable of ejecting.
 436           EBUSY         Door is locked
 437
 438
 439
 440
 441 CDROMMULTISESSION               Obtain the start-of-last-session
 442                                   address of multi session disks
 443                                   (struct cdrom_multisession)
 444         usage:
 445
 446           struct cdrom_multisession ms_info;
 447           ioctl(fd, CDROMMULTISESSION, &ms_info);
 448
 449         inputs:
 450           cdrom_multisession structure containing desired
 451           format.
 452
 453         outputs:
 454           cdrom_multisession structure is filled with last_session
 455           information.
 456
 457         error return:
 458           EINVAL        format not CDROM_MSF or CDROM_LBA
 459
 460
 461 CDROM_GET_MCN                   Obtain the "Universal Product Code"
 462                                    if available (struct cdrom_mcn)
 463
 464         usage:
 465
 466           struct cdrom_mcn mcn;
 467           ioctl(fd, CDROM_GET_MCN, &mcn);
 468
 469         inputs:         none
 470
 471         outputs:
 472           Universal Product Code
 473
 474         error return:
 475           ENOSYS        Drive is not capable of reading MCN data.
 476
 477         notes:
 478           Source code comments state:
 479
 480             The following function is implemented, although very few
 481             audio discs give Universal Product Code information, which
 482             should just be the Medium Catalog Number on the box.  Note,
 483             that the way the code is written on the CD is /not/ uniform
 484             across all discs!
 485
 486
 487
 488
 489 CDROM_GET_UPC                   CDROM_GET_MCN  (deprecated)
 490
 491         Not implemented, as of 2.6.8.1
 492
 493
 494
 495 CDROMRESET                      hard-reset the drive
 496
 497         usage:
 498
 499           ioctl(fd, CDROMRESET, 0);
 500
 501         inputs:         none
 502
 503         outputs:        none
 504
 505         error return:
 506           EACCES        Access denied:  requires CAP_SYS_ADMIN
 507           ENOSYS        Drive is not capable of resetting.
 508
 509
 510
 511
 512 CDROMREADCOOKED                 read data in cooked mode
 513
 514         usage:
 515
 516           u8 buffer[CD_FRAMESIZE]
 517           ioctl(fd, CDROMREADCOOKED, buffer);
 518
 519         inputs:         none
 520
 521         outputs:
 522           2048 bytes of data, "cooked" mode.
 523
 524         notes:
 525           Not implemented on all drives.
 526
 527
 528
 529
 530 CDROMREADALL                    read all 2646 bytes
 531
 532         Same as CDROMREADCOOKED, but reads 2646 bytes.
 533
 534
 535
 536 CDROMSEEK                       seek msf address
 537
 538         usage:
 539
 540           struct cdrom_msf msf;
 541           ioctl(fd, CDROMSEEK, &msf);
 542
 543         inputs:
 544           MSF address to seek to.
 545
 546         outputs:        none
 547
 548
 549
 550 CDROMPLAYBLK                    scsi-cd only, (struct cdrom_blk)
 551
 552         usage:
 553
 554           struct cdrom_blk blk;
 555           ioctl(fd, CDROMPLAYBLK, &blk);
 556
 557         inputs:
 558           Region to play
 559
 560         outputs:        none
 561
 562
 563
 564 CDROMGETSPINDOWN
 565
 566         usage:
 567
 568           char spindown;
 569           ioctl(fd, CDROMGETSPINDOWN, &spindown);
 570
 571         inputs:         none
 572
 573         outputs:
 574           The value of the current 4-bit spindown value.
 575
 576
 577
 578
 579 CDROMSETSPINDOWN
 580
 581         usage:
 582
 583           char spindown
 584           ioctl(fd, CDROMSETSPINDOWN, &spindown);
 585
 586         inputs:
 587           4-bit value used to control spindown (TODO: more detail here)
 588
 589         outputs:        none
 590
 591
 592
 593
 594
 595 CDROM_SET_OPTIONS               Set behavior options
 596
 597         usage:
 598
 599           int options;
 600           ioctl(fd, CDROM_SET_OPTIONS, options);
 601
 602         inputs:
 603           New values for drive options.  The logical 'or' of:
 604             CDO_AUTO_CLOSE      close tray on first open(2)
 605             CDO_AUTO_EJECT      open tray on last release
 606             CDO_USE_FFLAGS      use O_NONBLOCK information on open
 607             CDO_LOCK            lock tray on open files
 608             CDO_CHECK_TYPE      check type on open for data
 609
 610         outputs:
 611           Returns the resulting options settings in the
 612           ioctl return value.  Returns -1 on error.
 613
 614         error return:
 615           ENOSYS        selected option(s) not supported by drive.
 616
 617
 618
 619
 620 CDROM_CLEAR_OPTIONS             Clear behavior options
 621
 622         Same as CDROM_SET_OPTIONS, except that selected options are
 623         turned off.
 624
 625
 626
 627 CDROM_SELECT_SPEED              Set the CD-ROM speed
 628
 629         usage:
 630
 631           int speed;
 632           ioctl(fd, CDROM_SELECT_SPEED, speed);
 633
 634         inputs:
 635           New drive speed.
 636
 637         outputs:        none
 638
 639         error return:
 640           ENOSYS        speed selection not supported by drive.
 641
 642
 643
 644 CDROM_SELECT_DISC               Select disc (for juke-boxes)
 645
 646         usage:
 647
 648           int disk;
 649           ioctl(fd, CDROM_SELECT_DISC, disk);
 650
 651         inputs:
 652           Disk to load into drive.
 653
 654         outputs:        none
 655
 656         error return:
 657           EINVAL        Disk number beyond capacity of drive
 658
 659
 660
 661 CDROM_MEDIA_CHANGED             Check is media changed
 662
 663         usage:
 664
 665           int slot;
 666           ioctl(fd, CDROM_MEDIA_CHANGED, slot);
 667
 668         inputs:
 669           Slot number to be tested, always zero except for jukeboxes.
 670           May also be special values CDSL_NONE or CDSL_CURRENT
 671
 672         outputs:
 673           Ioctl return value is 0 or 1 depending on whether the media
 674           has been changed, or -1 on error.
 675
 676         error returns:
 677           ENOSYS        Drive can't detect media change
 678           EINVAL        Slot number beyond capacity of drive
 679           ENOMEM        Out of memory
 680
 681
 682
 683 CDROM_DRIVE_STATUS              Get tray position, etc.
 684
 685         usage:
 686
 687           int slot;
 688           ioctl(fd, CDROM_DRIVE_STATUS, slot);
 689
 690         inputs:
 691           Slot number to be tested, always zero except for jukeboxes.
 692           May also be special values CDSL_NONE or CDSL_CURRENT
 693
 694         outputs:
 695           Ioctl return value will be one of the following values
 696           from <linux/cdrom.h>:
 697
 698             CDS_NO_INFO         Information not available.
 699             CDS_NO_DISC
 700             CDS_TRAY_OPEN
 701             CDS_DRIVE_NOT_READY
 702             CDS_DISC_OK
 703             -1                  error
 704
 705         error returns:
 706           ENOSYS        Drive can't detect drive status
 707           EINVAL        Slot number beyond capacity of drive
 708           ENOMEM        Out of memory
 709
 710
 711
 712
 713 CDROM_DISC_STATUS               Get disc type, etc.
 714
 715         usage:
 716
 717           ioctl(fd, CDROM_DISC_STATUS, 0);
 718
 719         inputs:         none
 720
 721         outputs:
 722           Ioctl return value will be one of the following values
 723           from <linux/cdrom.h>:
 724             CDS_NO_INFO
 725             CDS_AUDIO
 726             CDS_MIXED
 727             CDS_XA_2_2
 728             CDS_XA_2_1
 729             CDS_DATA_1
 730
 731         error returns:  none at present
 732
 733         notes:
 734           Source code comments state:
 735
 736             Ok, this is where problems start.  The current interface for
 737             the CDROM_DISC_STATUS ioctl is flawed.  It makes the false
 738             assumption that CDs are all CDS_DATA_1 or all CDS_AUDIO, etc.
 739             Unfortunately, while this is often the case, it is also
 740             very common for CDs to have some tracks with data, and some
 741             tracks with audio.  Just because I feel like it, I declare
 742             the following to be the best way to cope.  If the CD has
 743             ANY data tracks on it, it will be returned as a data CD.
 744             If it has any XA tracks, I will return it as that.  Now I
 745             could simplify this interface by combining these returns with
 746             the above, but this more clearly demonstrates the problem
 747             with the current interface.  Too bad this wasn't designed
 748             to use bitmasks...         -Erik
 749
 750             Well, now we have the option CDS_MIXED: a mixed-type CD.
 751             User level programmers might feel the ioctl is not very
 752             useful.
 753                         ---david
 754
 755
 756
 757
 758 CDROM_CHANGER_NSLOTS            Get number of slots
 759
 760         usage:
 761
 762           ioctl(fd, CDROM_CHANGER_NSLOTS, 0);
 763
 764         inputs:         none
 765
 766         outputs:
 767           The ioctl return value will be the number of slots in a
 768           CD changer.  Typically 1 for non-multi-disk devices.
 769
 770         error returns:  none
 771
 772
 773
 774 CDROM_LOCKDOOR                  lock or unlock door
 775
 776         usage:
 777
 778           int lock;
 779           ioctl(fd, CDROM_LOCKDOOR, lock);
 780
 781         inputs:
 782           Door lock flag, 1=lock, 0=unlock
 783
 784         outputs:        none
 785
 786         error returns:
 787           EDRIVE_CANT_DO_THIS   Door lock function not supported.
 788           EBUSY                 Attempt to unlock when multiple users
 789                                 have the drive open and not CAP_SYS_ADMIN
 790
 791         notes:
 792           As of 2.6.8.1, the lock flag is a global lock, meaning that
 793           all CD drives will be locked or unlocked together.  This is
 794           probably a bug.
 795
 796           The EDRIVE_CANT_DO_THIS value is defined in <linux/cdrom.h>
 797           and is currently (2.6.8.1) the same as EOPNOTSUPP
 798
 799
 800
 801 CDROM_DEBUG                     Turn debug messages on/off
 802
 803         usage:
 804
 805           int debug;
 806           ioctl(fd, CDROM_DEBUG, debug);
 807
 808         inputs:
 809           Cdrom debug flag, 0=disable, 1=enable
 810
 811         outputs:
 812           The ioctl return value will be the new debug flag.
 813
 814         error return:
 815           EACCES        Access denied:  requires CAP_SYS_ADMIN
 816
 817
 818
 819 CDROM_GET_CAPABILITY            get capabilities
 820
 821         usage:
 822
 823           ioctl(fd, CDROM_GET_CAPABILITY, 0);
 824
 825         inputs:         none
 826
 827         outputs:
 828           The ioctl return value is the current device capability
 829           flags.  See CDC_CLOSE_TRAY, CDC_OPEN_TRAY, etc.
 830
 831
 832
 833 CDROMAUDIOBUFSIZ                set the audio buffer size
 834
 835         usage:
 836
 837           int arg;
 838           ioctl(fd, CDROMAUDIOBUFSIZ, val);
 839
 840         inputs:
 841           New audio buffer size
 842
 843         outputs:
 844           The ioctl return value is the new audio buffer size, or -1
 845           on error.
 846
 847         error return:
 848           ENOSYS        Not supported by this driver.
 849
 850         notes:
 851           Not supported by all drivers.
 852
 853
 854
 855 DVD_READ_STRUCT                 Read structure
 856
 857         usage:
 858
 859           dvd_struct s;
 860           ioctl(fd, DVD_READ_STRUCT, &s);
 861
 862         inputs:
 863           dvd_struct structure, containing:
 864             type                specifies the information desired, one of
 865                                 DVD_STRUCT_PHYSICAL, DVD_STRUCT_COPYRIGHT,
 866                                 DVD_STRUCT_DISCKEY, DVD_STRUCT_BCA,
 867                                 DVD_STRUCT_MANUFACT
 868             physical.layer_num  desired layer, indexed from 0
 869             copyright.layer_num desired layer, indexed from 0
 870             disckey.agid
 871
 872         outputs:
 873           dvd_struct structure, containing:
 874             physical            for type == DVD_STRUCT_PHYSICAL
 875             copyright           for type == DVD_STRUCT_COPYRIGHT
 876             disckey.value       for type == DVD_STRUCT_DISCKEY
 877             bca.{len,value}     for type == DVD_STRUCT_BCA
 878             manufact.{len,valu} for type == DVD_STRUCT_MANUFACT
 879
 880         error returns:
 881           EINVAL        physical.layer_num exceeds number of layers
 882           EIO           Received invalid response from drive
 883
 884
 885
 886 DVD_WRITE_STRUCT                Write structure
 887
 888         Not implemented, as of 2.6.8.1
 889
 890
 891
 892 DVD_AUTH                        Authentication
 893
 894         usage:
 895
 896           dvd_authinfo ai;
 897           ioctl(fd, DVD_AUTH, &ai);
 898
 899         inputs:
 900           dvd_authinfo structure.  See <linux/cdrom.h>
 901
 902         outputs:
 903           dvd_authinfo structure.
 904
 905         error return:
 906           ENOTTY        ai.type not recognized.
 907
 908
 909
 910 CDROM_SEND_PACKET               send a packet to the drive
 911
 912         usage:
 913
 914           struct cdrom_generic_command cgc;
 915           ioctl(fd, CDROM_SEND_PACKET, &cgc);
 916
 917         inputs:
 918           cdrom_generic_command structure containing the packet to send.
 919
 920         outputs:        none
 921           cdrom_generic_command structure containing results.
 922
 923         error return:
 924           EIO           command failed.
 925           EPERM         Operation not permitted, either because a
 926                         write command was attempted on a drive which
 927                         is opened read-only, or because the command
 928                         requires CAP_SYS_RAWIO
 929           EINVAL        cgc.data_direction not set
 930
 931
 932
 933 CDROM_NEXT_WRITABLE             get next writable block
 934
 935         usage:
 936
 937           long next;
 938           ioctl(fd, CDROM_NEXT_WRITABLE, &next);
 939
 940         inputs:         none
 941
 942         outputs:
 943           The next writable block.
 944
 945         notes:
 946           If the device does not support this ioctl directly, the
 947           ioctl will return CDROM_LAST_WRITTEN + 7.
 948
 949
 950
 951 CDROM_LAST_WRITTEN              get last block written on disc
 952
 953         usage:
 954
 955           long last;
 956           ioctl(fd, CDROM_LAST_WRITTEN, &last);
 957
 958         inputs:         none
 959
 960         outputs:
 961           The last block written on disc
 962
 963         notes:
 964           If the device does not support this ioctl directly, the
 965           result is derived from the disc's table of contents.  If the
 966           table of contents can't be read, this ioctl returns an
 967           error.