Edit File: ioctl.h
#ifndef _ASM_GENERIC_IOCTL_H #define _ASM_GENERIC_IOCTL_H /* ioctl command encoding: 32 bits total, command in lower 16 bits, * size of the parameter structure in the lower 14 bits of the * upper 16 bits. * Encoding the size of the parameter structure in the ioctl request * is useful for catching programs compiled with old versions * and to avoid overwriting user space outside the user buffer area. * The highest 2 bits are reserved for indicating the ``access mode''. * NOTE: This limits the max parameter size to 16kB -1 ! */ /* * The following is for compatibility across the various Linux * platforms. The generic ioctl numbering scheme doesn't really enforce * a type field. De facto, however, the top 8 bits of the lower 16 * bits are indeed used as a type field, so we might just as well make * this explicit here. Please be sure to use the decoding macros * below from now on. */ #define _IOC_NRBITS 8 #define _IOC_TYPEBITS 8 /* * Let any architecture override either of the following before * including this file. */ #ifndef _IOC_SIZEBITS # define _IOC_SIZEBITS 14 #endif #ifndef _IOC_DIRBITS # define _IOC_DIRBITS 2 #endif #define _IOC_NRMASK ((1 << _IOC_NRBITS)-1) #define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1) #define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1) #define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1) #define _IOC_NRSHIFT 0 #define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS) #define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS) #define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS) /* * Direction bits, which any architecture can choose to override * before including this file. * * NOTE: _IOC_WRITE means userland is writing and kernel is * reading. _IOC_READ means userland is reading and kernel is writing. */ #ifndef _IOC_NONE # define _IOC_NONE 0U #endif #ifndef _IOC_WRITE # define _IOC_WRITE 1U #endif #ifndef _IOC_READ # define _IOC_READ 2U #endif #define _IOC(dir,type,nr,size) \ (((dir) << _IOC_DIRSHIFT) | \ ((type) << _IOC_TYPESHIFT) | \ ((nr) << _IOC_NRSHIFT) | \ ((size) << _IOC_SIZESHIFT)) #define _IOC_TYPECHECK(t) (sizeof(t)) /* * Used to create numbers. * * NOTE: _IOW means userland is writing and kernel is reading. _IOR * means userland is reading and kernel is writing. */ #define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0) #define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),(_IOC_TYPECHECK(size))) #define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size))) #define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size))) #define _IOR_BAD(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size)) #define _IOW_BAD(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size)) #define _IOWR_BAD(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size)) /* used to decode ioctl numbers.. */ #define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK) #define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK) #define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK) #define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK) /* ...and for the drivers/sound files... */ #define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT) #define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT) #define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT) #define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT) #define IOCSIZE_SHIFT (_IOC_SIZESHIFT) #endif /* _ASM_GENERIC_IOCTL_H */