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fix: make _safe_write_json actually atomic with mkstemp + os.replace #3971

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fix: make _safe_write_json actually atomic with mkstemp + os.replace #3971

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18 changes: 16 additions & 2 deletions src/specify_cli/events.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
import sys
import subprocess
import platform
import tempfile
from pathlib import Path
from typing import TYPE_CHECKING, Any

Expand Down Expand Up @@ -2010,10 +2011,23 @@ def _load_user_json(path: Path) -> dict | None:


def _safe_write_json(dst: Path, data: dict) -> None:
"""Write *data* as JSON to *dst* after validating the destination (#12)."""
"""Write *data* as JSON to *dst* atomically after validating the destination (#12)."""
_ensure_safe_destination(dst)
dst.parent.mkdir(parents=True, exist_ok=True)
dst.write_text(json.dumps(data, indent=2) + "\n", encoding="utf-8")
fd, tmp = tempfile.mkstemp(
dir=str(dst.parent), prefix=f".{dst.name}.", suffix=".tmp"
)
try:
with os.fdopen(fd, "w", encoding="utf-8") as f:
json.dump(data, f, indent=2)
f.write("\n")
os.replace(tmp, dst)
except BaseException:
try:
os.unlink(tmp)
except OSError:
pass
raise


def _ensure_safe_destination(dst: Path) -> None:
Expand Down