ioctl.h 3.4 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. /*
  23. * Let any architecture override either of the following before
  24. * including this file.
  25. */
  26. #ifndef _IOC_SIZEBITS
  27. # define _IOC_SIZEBITS 14
  28. #endif
  29. #ifndef _IOC_DIRBITS
  30. # define _IOC_DIRBITS 2
  31. #endif
  32. #define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
  33. #define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
  34. #define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1)
  35. #define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1)
  36. #define _IOC_NRSHIFT 0
  37. #define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS)
  38. #define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS)
  39. #define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)
  40. /*
  41. * Direction bits, which any architecture can choose to override
  42. * before including this file.
  43. */
  44. #ifndef _IOC_NONE
  45. # define _IOC_NONE 0U
  46. #endif
  47. #ifndef _IOC_WRITE
  48. # define _IOC_WRITE 1U
  49. #endif
  50. #ifndef _IOC_READ
  51. # define _IOC_READ 2U
  52. #endif
  53. #define _IOC(dir,type,nr,size) \
  54. (((dir) << _IOC_DIRSHIFT) | \
  55. ((type) << _IOC_TYPESHIFT) | \
  56. ((nr) << _IOC_NRSHIFT) | \
  57. ((size) << _IOC_SIZESHIFT))
  58. #ifdef __KERNEL__
  59. /* provoke compile error for invalid uses of size argument */
  60. extern unsigned int __invalid_size_argument_for_IOC;
  61. #define _IOC_TYPECHECK(t) \
  62. ((sizeof(t) == sizeof(t[1]) && \
  63. sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
  64. sizeof(t) : __invalid_size_argument_for_IOC)
  65. #else
  66. #define _IOC_TYPECHECK(t) (sizeof(t))
  67. #endif
  68. /* used to create numbers */
  69. #define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
  70. #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size)))
  71. #define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  72. #define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))
  73. #define _IOR_BAD(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
  74. #define _IOW_BAD(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
  75. #define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
  76. /* used to decode ioctl numbers.. */
  77. #define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
  78. #define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
  79. #define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
  80. #define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
  81. /* ...and for the drivers/sound files... */
  82. #define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT)
  83. #define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT)
  84. #define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
  85. #define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
  86. #define IOCSIZE_SHIFT (_IOC_SIZESHIFT)
  87. #endif /* _ASM_GENERIC_IOCTL_H */