b728fdd627
pm imported runtime_state's private helpers (_lock, _atomic_bytes, _bytes, _digest) at a dozen sites while runtime_state imports pm.environments at module top. The primitives are pm's: move them into the stdlib-only pm.filesystem as lock_fd, durable_write_bytes, read_bytes_or_none and file_digest, and repoint every pm caller. runtime_state keeps the private names only as import aliases: it still calls them through its own globals, and pre-PM updaters load them by these names mid-swap (tests/compat/old_updater_surface.json). Boot-subset test fixtures now copy pm/filesystem.py, since runtime_state imports it at process boot; worker-injection tests patch the name pm.publication now reads.
83 lines
2.7 KiB
Python
83 lines
2.7 KiB
Python
"""Stdlib-only filesystem primitives PM needs before it can replace the caller's interpreter.
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Boot-time dependency selection (``hermes_cli.runtime_state``) imports these, so nothing here
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may import a dependency or another PM module.
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"""
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from __future__ import annotations
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import errno
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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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_LOCK_POLL_SECONDS = 0.05
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def is_junction(path: Path) -> bool:
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"""Keep junctions opaque even before Python 3.12's Path.is_junction exists."""
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return os.name == "nt" and path.lstat().st_reparse_tag == stat.IO_REPARSE_TAG_MOUNT_POINT
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def lock_fd(fd: int, *, wait: bool, timeout: float | None = None) -> bool:
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"""Take the byte lock; ``timeout`` bounds the retry loop (None waits forever, 0 tries once)."""
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deadline = None if timeout is None else time.monotonic() + timeout
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if os.name == "nt":
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import msvcrt
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while True:
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try:
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os.lseek(fd, 0, os.SEEK_SET)
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msvcrt.locking(fd, msvcrt.LK_NBLCK, 1)
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return True
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except OSError as exc:
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if exc.errno not in (errno.EACCES, errno.EAGAIN, errno.EDEADLK):
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raise
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if not wait or (deadline is not None and time.monotonic() >= deadline):
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return False
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time.sleep(_LOCK_POLL_SECONDS)
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else:
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import fcntl
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while True:
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try:
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fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
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return True
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except BlockingIOError:
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pass
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if not wait or (deadline is not None and time.monotonic() >= deadline):
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return False
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time.sleep(_LOCK_POLL_SECONDS)
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def read_bytes_or_none(path: Path) -> bytes | None:
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try:
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return path.read_bytes()
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except FileNotFoundError:
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return None
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def file_digest(path: Path) -> str | None:
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data = read_bytes_or_none(path)
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return hashlib.sha256(data).hexdigest() if data is not None else None
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def durable_write_bytes(path: Path, data: bytes) -> None:
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"""Replace ``path`` atomically and fsync file and directory so a crash keeps old or new bytes."""
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path.parent.mkdir(parents=True, exist_ok=True)
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fd, temporary = tempfile.mkstemp(dir=path.parent, prefix=".publish-")
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try:
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with os.fdopen(fd, "wb") as stream:
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stream.write(data)
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stream.flush()
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os.fsync(stream.fileno())
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os.replace(temporary, path)
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if os.name != "nt":
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directory = os.open(path.parent, os.O_RDONLY)
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try:
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os.fsync(directory)
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finally:
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os.close(directory)
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finally:
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Path(temporary).unlink(missing_ok=True)
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