Functions to compute fnctl.ioctl's opt argument
Project description
Pythonified linux asm-generic/ioctl.h .
So you can replicate driver’s code computing fcntl.ioctl’s opt argument.
For example, starting from the following IOCTL declaration (taken from input.h):
#include <sys/ioctl.h> #define EVIOCGNAME(len) _IOC(_IOC_READ, 'E', 0x06, len) /* get device name */
you could write the following:
from ioctl_opt import IOC, IOC_READ EVIOCGNAME = lambda length: IOC(IOC_READ, ord('E'), 0x06, length)
The differences are minimal, and all come from python language or coding style:
- macros/constants to use from ioctl_opt for not start with an underscore
- defined macro becomes a callable (here a lambda, could be function)
- IOC’s nr argument has to be an integer, so C’s single-quote char becomes an ord call
- avoid shadowing built-in len function
You may want to then write a pythonic function to conveniently access that ioctl:
import ctypes import fcntl def getDeviceName(fd, length=1024): name = (ctypes.c_char * length)() actual_length = fcntl.ioctl(fd, EVIOCGNAME(length), name, True) if actual_length < 0: raise OSError(-actual_length) if name[actual_length - 1] == b'\x00': actual_length -= 1 return name[:actual_length]
More advanced example defining hidraw ioctls, requiring structures (for more on how structures are defined, check python’s ctype documentation for your python version):
import ctypes from ioctl_opt import IOR, IOC, IOC_READ, IOC_WRITE # hid.h HID_MAX_DESCRIPTOR_SIZE = 4096 # hidraw.h class hidraw_report_descriptor(ctypes.Structure): _fields_ = [ ('size', ctypes.c_uint), ('value', ctypes.c_ubyte * HID_MAX_DESCRIPTOR_SIZE), ] class hidraw_devinfo(ctypes.Structure): _fields_ = [ ('bustype', ctypes.c_uint), ('vendor', ctypes.c_short), ('product', ctypes.c_short), ] HIDIOCGRDESCSIZE = IOR(ord('H'), 0x01, ctypes.c_int) HIDIOCGRDESC = IOR(ord('H'), 0x02, hidraw_report_descriptor) HIDIOCGRAWINFO = IOR(ord('H'), 0x03, hidraw_devinfo) HIDIOCGRAWNAME = lambda length: IOC(IOC_READ, ord('H'), 0x04, length) HIDIOCGRAWPHYS = lambda length: IOC(IOC_READ, ord('H'), 0x05, length) HIDIOCSFEATURE = lambda length: IOC(IOC_WRITE|IOC_READ, ord('H'), 0x06, length) HIDIOCGFEATURE = lambda length: IOC(IOC_WRITE|IOC_READ, ord('H'), 0x07, length)
Project details
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Source Distribution
ioctl-opt-1.2.2.tar.gz
(3.4 kB
view hashes)