1 # Copyright (c) 2011 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 # Description: 6 # 7 # Python version of include/asm-generic/ioctl.h 8 9 10 import struct 11 12 13 # ioctl command encoding: 32 bits total, command in lower 16 bits, 14 # size of the parameter structure in the lower 14 bits of the 15 # upper 16 bits. 16 # Encoding the size of the parameter structure in the ioctl request 17 # is useful for catching programs compiled with old versions 18 # and to avoid overwriting user space outside the user buffer area. 19 # The highest 2 bits are reserved for indicating the ``access mode''. 20 # NOTE: This limits the max parameter size to 16kB -1 ! 21 22 _IOC_NRBITS = 8 23 _IOC_TYPEBITS = 8 24 _IOC_SIZEBITS = 14 25 _IOC_DIRBITS = 2 26 27 _IOC_NRMASK = ((1 << _IOC_NRBITS) - 1) 28 _IOC_TYPEMASK = ((1 << _IOC_TYPEBITS) - 1) 29 _IOC_SIZEMASK = ((1 << _IOC_SIZEBITS) - 1) 30 _IOC_DIRMASK = ((1 << _IOC_DIRBITS) - 1) 31 32 _IOC_NRSHIFT = 0 33 _IOC_TYPESHIFT = (_IOC_NRSHIFT + _IOC_NRBITS) 34 _IOC_SIZESHIFT = (_IOC_TYPESHIFT + _IOC_TYPEBITS) 35 _IOC_DIRSHIFT = (_IOC_SIZESHIFT + _IOC_SIZEBITS) 36 37 IOC_NONE = 0 38 IOC_WRITE = 1 39 IOC_READ = 2 40 41 # Return the byte size of a python struct format string 42 def sizeof(t): 43 return struct.calcsize(t) 44 45 def IOC(d, t, nr, size): 46 return ((d << _IOC_DIRSHIFT) | (ord(t) << _IOC_TYPESHIFT) | 47 (nr << _IOC_NRSHIFT) | (size << _IOC_SIZESHIFT)) 48 49 # used to create numbers 50 def IO(t, nr, t_format): 51 return IOC(IOC_NONE, t, nr, 0) 52 53 def IOW(t, nr, t_format): 54 return IOC(IOC_WRITE, t, nr, sizeof(t_format)) 55 56 def IOR(t, nr, t_format): 57 return IOC(IOC_READ, t, nr, sizeof(t_format)) 58 59 def IOWR(t, nr, t_format): 60 return IOC(IOC_READ|_IOC_WRITE, t, nr, sizeof(t_format)) 61 62 # used to decode ioctl numbers.. 63 def IOC_DIR(nr): 64 return ((nr >> _IOC_DIRSHIFT) & _IOC_DIRMASK) 65 66 def IOC_TYPE(nr): 67 return ((nr >> _IOC_TYPESHIFT) & _IOC_TYPEMASK) 68 69 def IOC_NR(nr): 70 return ((nr >> _IOC_NRSHIFT) & _IOC_NRMASK) 71 72 def IOC_SIZE(nr): 73 return ((nr >> _IOC_SIZESHIFT) & _IOC_SIZEMASK) 74 75 # ...and for the drivers/sound files... 76 IOC_IN = (IOC_WRITE << _IOC_DIRSHIFT) 77 IOC_OUT = (IOC_READ << _IOC_DIRSHIFT) 78 IOC_INOUT = ((IOC_WRITE | IOC_READ) << _IOC_DIRSHIFT) 79 IOCSIZE_MASK = (_IOC_SIZEMASK << _IOC_SIZESHIFT) 80 IOCSIZE_SHIFT = (_IOC_SIZESHIFT) 81 82
