mirror of
https://github.com/firestar5683/StarPilot.git
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firestar5683
7b1cc1f8e2
Serve fresh camera snapshots with explicit image responses and expose live crop controls without placing file or camera startup work on the UI thread.
88 lines
2.4 KiB
Python
88 lines
2.4 KiB
Python
"""Short, namespaced camera leases. Manager alone owns camera processes."""
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import fcntl
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import hashlib
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import os
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from pathlib import Path
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import stat
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import tempfile
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import time
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TTL_NS = 15_000_000_000
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FRAME_TTL_NS = 5_000_000_000
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def boot_ns():
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return time.clock_gettime_ns(getattr(time, 'CLOCK_BOOTTIME', time.CLOCK_MONOTONIC))
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def _path(name):
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prefix = os.environ.get('OPENPILOT_PREFIX', 'd')
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namespace = hashlib.sha256(prefix.encode()).hexdigest()[:16]
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return Path('/dev/shm') / f'starpilot-camera-{os.getuid()}-{namespace}' / name
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def _read(path):
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fd = os.open(path, os.O_RDONLY | os.O_NOFOLLOW | os.O_NONBLOCK)
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try:
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info = os.fstat(fd)
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if not stat.S_ISREG(info.st_mode) or info.st_uid != os.getuid() or info.st_size > 32:
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raise ValueError('Invalid camera lease')
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return int(os.read(fd, 32))
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finally:
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os.close(fd)
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def _write(path, value):
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path = Path(path)
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path.parent.mkdir(mode=0o700, parents=True, exist_ok=True)
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info = path.parent.lstat()
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if not stat.S_ISDIR(info.st_mode) or info.st_uid != os.getuid() or info.st_mode & 0o077:
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raise OSError('Camera lease directory is not private')
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lock = os.open(path.with_name(path.name + '.lock'), os.O_WRONLY | os.O_CREAT | os.O_NOFOLLOW | os.O_NONBLOCK, 0o600)
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temporary = None
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try:
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info = os.fstat(lock)
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if not stat.S_ISREG(info.st_mode) or info.st_uid != os.getuid():
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raise OSError('Invalid camera lease lock')
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fcntl.flock(lock, fcntl.LOCK_EX)
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try:
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previous = _read(path)
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if abs(previous - value) <= TTL_NS:
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value = max(value, previous)
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except (OSError, ValueError):
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pass
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fd, temporary = tempfile.mkstemp(prefix=path.name + '.', dir=path.parent)
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try:
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os.write(fd, str(value).encode())
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finally:
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os.close(fd)
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os.replace(temporary, path)
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temporary = None
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finally:
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if temporary is not None:
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os.unlink(temporary)
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os.close(lock)
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def request(clock=boot_ns, path=None):
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_write(path or _path('lease'), clock() + TTL_NS)
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def requested(clock=boot_ns, path=None):
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try:
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remaining = _read(path or _path('lease')) - clock()
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return 0 < remaining <= TTL_NS
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except (OSError, ValueError):
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return False
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def mark_frame(clock=boot_ns, path=None):
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_write(path or _path('cabin-frame'), clock())
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def frame_available(clock=boot_ns, path=None):
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try:
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return 0 <= clock() - _read(path or _path('cabin-frame')) <= FRAME_TTL_NS
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except (OSError, ValueError):
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return False
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