Justin
117 lines
4.5 KiB
Python
117 lines
4.5 KiB
Python
"""Linux hidraw access, limited to the BTD 700 control interface."""
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from .i18n import tr
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from dataclasses import dataclass
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from pathlib import Path
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import fcntl
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import os
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import select
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import struct
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import time
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from .protocol import Command, EVENTS, MIN_LENGTHS, ProtocolError, acknowledge, decode, encode
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class DeviceError(Exception):
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pass
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@dataclass(frozen=True)
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class Device:
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path: str
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serial: str
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name: str = 'Sennheiser BTD 700'
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def discover(sysfs: Path = Path('/sys/class/hidraw')) -> list[Device]:
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devices = []
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for node in sorted(sysfs.glob('hidraw*')):
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try:
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info = dict(line.split('=', 1) for line in (node / 'device/uevent').read_text().splitlines() if '=' in line)
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if info.get('HID_ID', '').upper() != '0003:00003542:00003001':
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continue
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descriptor = (node / 'device/report_descriptor').read_bytes()
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if b'\x06\xa2\xff' not in descriptor or b'\x85\x34' not in descriptor:
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continue
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devices.append(Device('/dev/' + node.name, info.get('HID_UNIQ', '')))
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except (OSError, ValueError):
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continue
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return devices
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class Hidraw:
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def __init__(self, device: Device, timeout: float = 1.0):
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self.device = device
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self.timeout = timeout
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self.fd = None
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self.events = {}
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try:
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self.fd = os.open(device.path, os.O_RDWR | os.O_NONBLOCK | os.O_CLOEXEC | os.O_NOFOLLOW)
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info = bytearray(8)
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fcntl.ioctl(self.fd, 0x80084803, info, True) # HIDIOCGRAWINFO
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bus, vendor, product = struct.unpack('IHH', info)
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if (bus, vendor, product) != (3, 0x3542, 0x3001):
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raise DeviceError(tr('Gerätepfad gehört nicht mehr zum BTD 700.'))
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try:
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fcntl.flock(self.fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
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except BlockingIOError as exc:
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raise DeviceError(tr('Der Dongle ist bereits in einer anderen Instanz geöffnet.')) from exc
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except PermissionError as exc:
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self.close()
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raise DeviceError(tr('USB-Zugriff fehlt. Die mitgelieferte udev-Regel installieren und den Dongle neu einstecken.')) from exc
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except BaseException:
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self.close()
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raise
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def close(self):
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if self.fd is not None:
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os.close(self.fd)
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self.fd = None
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def __enter__(self):
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return self
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def __exit__(self, *_):
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self.close()
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def _write(self, report):
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if self.fd is None:
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raise DeviceError(tr('Dongle ist nicht geöffnet.'))
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if not select.select([], [self.fd], [], self.timeout)[1]:
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raise TimeoutError(tr('USB-Schreibzugriff hat nicht geantwortet.'))
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if os.write(self.fd, report) != len(report):
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raise DeviceError(tr('Unvollständiger USB-Schreibvorgang.'))
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def _receive(self):
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report = os.read(self.fd, 1024)
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if not report:
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raise DeviceError(tr('Dongle wurde entfernt.'))
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message = decode(report)
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if message and message.kind == 0xFC and message.command in EVENTS:
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self.events[message.command] = message.payload
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self._write(acknowledge(message.command))
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return message
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def request(self, command: Command, payload: bytes = b'') -> bytes:
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report = encode(command, payload) # Validate before any I/O.
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try:
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# Discard stale replies, acknowledging events. The cap prevents an
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# unrelated consumer-control input flood from blocking indefinitely.
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for _ in range(128):
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if not select.select([self.fd], [], [], 0)[0]:
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break
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self._receive()
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self._write(report)
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deadline = time.monotonic() + self.timeout
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while (remaining := deadline - time.monotonic()) > 0:
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if not select.select([self.fd], [], [], remaining)[0]:
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break
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message = self._receive()
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if message and message.kind == 0xFF and message.command == command:
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if len(message.payload) < MIN_LENGTHS.get(command, 0):
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raise ProtocolError(tr('Unvollständige Antwort auf {command}.').format(command=command.name))
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return message.payload
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raise TimeoutError(tr('Der Dongle antwortet nicht auf {command}.').format(command=command.name))
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except (OSError, ProtocolError):
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self.close()
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raise
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