ioctl.h 3.0 KB

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  1. #ifndef _ASM_GENERIC_IOCTL_H
  2. #define _ASM_GENERIC_IOCTL_H
  3. /* ioctl command encoding: 32 bits total, command in lower 16 bits,
  4. * size of the parameter structure in the lower 14 bits of the
  5. * upper 16 bits.
  6. * Encoding the size of the parameter structure in the ioctl request
  7. * is useful for catching programs compiled with old versions
  8. * and to avoid overwriting user space outside the user buffer area.
  9. * The highest 2 bits are reserved for indicating the ``access mode''.
  10. * NOTE: This limits the max parameter size to 16kB -1 !
  11. */
  12. /*
  13. * The following is for compatibility across the various Linux
  14. * platforms. The generic ioctl numbering scheme doesn't really enforce
  15. * a type field. De facto, however, the top 8 bits of the lower 16
  16. * bits are indeed used as a type field, so we might just as well make
  17. * this explicit here. Please be sure to use the decoding macros
  18. * below from now on.
  19. */
  20. #define _IOC_NRBITS 8
  21. #define _IOC_TYPEBITS 8
  22. #define _IOC_SIZEBITS 14
  23. #define _IOC_DIRBITS 2
  24. #define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
  25. #define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
  26. #define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1)
  27. #define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1)
  28. #define _IOC_NRSHIFT 0
  29. #define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS)
  30. #define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS)
  31. #define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)
  32. /*
  33. * Direction bits.
  34. */
  35. #define _IOC_NONE 0U
  36. #define _IOC_WRITE 1U
  37. #define _IOC_READ 2U
  38. #define _IOC(dir,type,nr,size) \
  39. (((dir) << _IOC_DIRSHIFT) | \
  40. ((type) << _IOC_TYPESHIFT) | \
  41. ((nr) << _IOC_NRSHIFT) | \
  42. ((size) << _IOC_SIZESHIFT))
  43. /* provoke compile error for invalid uses of size argument */
  44. extern unsigned int __invalid_size_argument_for_IOC;
  45. #define _IOC_TYPECHECK(t) \
  46. ((sizeof(t) == sizeof(t[1]) && \
  47. sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
  48. sizeof(t) : __invalid_size_argument_for_IOC)
  49. /* used to create numbers */
  50. #define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
  51. #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
  52. #define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  53. #define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  54. #define _IOR_BAD(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
  55. #define _IOW_BAD(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
  56. #define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
  57. /* used to decode ioctl numbers.. */
  58. #define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
  59. #define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
  60. #define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
  61. #define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
  62. /* ...and for the drivers/sound files... */
  63. #define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT)
  64. #define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT)
  65. #define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
  66. #define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
  67. #define IOCSIZE_SHIFT (_IOC_SIZESHIFT)
  68. #endif /* _ASM_GENERIC_IOCTL_H */