47 lines
1.6 KiB
C
47 lines
1.6 KiB
C
/* $Id: ioctl.h,v 1.5 1993/07/19 21:53:50 root Exp root $
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*
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* linux/ioctl.h for Linux by H.H. Bergman.
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*/
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#ifndef _LINUX_IOCTL_H
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#define _LINUX_IOCTL_H
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/* ioctl command encoding: 32 bits total, command in lower 16 bits,
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* size of the parameter structure in the lower 14 bits of the
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* upper 16 bits.
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* Encoding the size of the parameter structure in the ioctl request
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* is useful for catching programs compiled with old versions
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* and to avoid overwriting user space outside the user buffer area.
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* The highest 2 bits are reserved for indicating the ``access mode''.
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* NOTE: This limits the max parameter size to 16kB -1 !
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*/
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#define IOC_VOID 0x00000000 /* param in size field */
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#define IOC_IN 0x40000000 /* user --> kernel */
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#define IOC_OUT 0x80000000 /* kernel --> user */
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#define IOC_INOUT (IOC_IN | IOC_OUT) /* both */
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#define IOCSIZE_MASK 0x3fff0000 /* size (max 16k-1 bytes) */
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#define IOCSIZE_SHIFT 16 /* how to get the size */
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#define IOCCMD_MASK 0x0000ffff /* command code */
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#define IOCCMD_SHIFT 0
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/* _IO(magic, subcode); size field is zero and the
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* subcode determines the command.
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*/
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#define _IO(c,d) (IOC_VOID | ((c)<<8) | (d)) /* param encoded */
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/* _IOXX(magic, subcode, arg_t); where arg_t is the type of the
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* (last) argument field in the ioctl call, if present.
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*/
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#define _IOW(c,d,t) (IOC_IN | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
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((c)<<8) | (d))
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#define _IOR(c,d,t) (IOC_OUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
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((c)<<8) | (d))
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/* WR rather than RW to avoid conflict with stdio.h */
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#define _IOWR(c,d,t) (IOC_INOUT | ((sizeof(t)<<16) & IOCSIZE_MASK) | \
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((c)<<8) | (d))
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#endif /* _LINUX_IOCTL_H */
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