d4cec15b47
Behavior-neutral structural pass over tools/*: god-file extractions into sibling modules (file_operations_common/lint/search, file_tools_paths/ read_tracking/write, code_execution_env/rpc, tool_search_catalog/names/ validation, tts_command_provider, ...), duplicate helper unification, if/elif -> dispatch tables, dead-code removal, docstring compaction. Tool schemas (get_tool_definitions) verified byte-identical to base.
102 lines
3.4 KiB
Python
102 lines
3.4 KiB
Python
"""Symlink-safe creation helpers for spill/cache files.
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Spill files (terminal output, hook context, subagent summaries, web_extract
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text) live in predictable directories under ``~/.hermes``; a plain
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``open(path, "w")`` there would follow a pre-planted symlink and let a local
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process redirect the write onto ``~/.bashrc``, ``authorized_keys``, etc.
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Every helper refuses symlinks by construction: new files use
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``O_CREAT | O_EXCL`` (fails on ANY existing path, including a dangling link);
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overwrites ``lstat`` + ``unlink`` the existing path first (removes the link,
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never its target) and then create exclusively, so the pair can't be raced.
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Privacy tiers: ``private=True`` (default) forces ``0o700`` dirs / ``0o600``
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files for spills that may hold pre-redaction secrets; ``private=False`` keeps
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umask-default perms for cache dirs bind-mounted into remote terminal backends
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(``credential_files._CACHE_DIRS``), where a non-root container UID must read them.
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Disk failures are the caller's concern: helpers raise ``OSError``.
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"""
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from __future__ import annotations
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import os
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import stat
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from pathlib import Path
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from typing import IO
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__all__ = [
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"ensure_spill_dir",
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"open_exclusive",
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"write_text_exclusive",
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]
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# O_NOFOLLOW is POSIX-only; on Windows O_EXCL alone already refuses every
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# pre-existing path.
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_O_NOFOLLOW = getattr(os, "O_NOFOLLOW", 0)
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def ensure_spill_dir(path: Path, *, private: bool = True) -> Path:
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"""Create ``path`` (and parents) as a directory, refusing symlinks.
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``private=True`` creates the leaf ``0o700`` and tightens an existing leaf to
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``0o700``. Raises ``OSError`` if the leaf is not a real directory.
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"""
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path = Path(path)
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path.mkdir(mode=0o700 if private else 0o777, parents=True, exist_ok=True)
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st = os.lstat(path)
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if not stat.S_ISDIR(st.st_mode):
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raise OSError(f"spill dir is not a directory (symlink?): {path}")
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if private and stat.S_IMODE(st.st_mode) != 0o700:
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os.chmod(path, 0o700)
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return path
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def open_exclusive(
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path: Path,
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*,
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private: bool = True,
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overwrite: bool = False,
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encoding: str = "utf-8",
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errors: str = "strict",
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) -> IO[str]:
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"""Open ``path`` for writing via exclusive create; never follows a link.
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``overwrite=True`` first unlinks an existing path (``lstat``-checked, so only
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the link itself is removed and directories are refused), then creates
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exclusively — the overwrite path cannot be redirected through a symlink either.
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"""
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path = Path(path)
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if overwrite:
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try:
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st = os.lstat(path)
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except FileNotFoundError:
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pass
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else:
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if stat.S_ISDIR(st.st_mode):
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raise OSError(f"refusing to overwrite a directory: {path}")
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os.unlink(path)
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mode = 0o600 if private else 0o666 # non-private honors umask
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fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_EXCL | _O_NOFOLLOW, mode)
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try:
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return os.fdopen(fd, "w", encoding=encoding, errors=errors)
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except Exception:
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os.close(fd)
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raise
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def write_text_exclusive(
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path: Path,
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text: str,
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*,
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private: bool = True,
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overwrite: bool = False,
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encoding: str = "utf-8",
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errors: str = "strict",
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) -> None:
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"""``Path.write_text`` equivalent that refuses to follow symlinks."""
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with open_exclusive(
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path, private=private, overwrite=overwrite, encoding=encoding, errors=errors
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) as fh:
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fh.write(text)
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