fix: make _safe_write_json actually atomic with mkstemp + os.replace - #3971
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Quratulain-bilal wants to merge 1 commit into
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fix: make _safe_write_json actually atomic with mkstemp + os.replace#3971Quratulain-bilal wants to merge 1 commit into
Quratulain-bilal wants to merge 1 commit into
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Despite its name, _safe_write_json used write_text() which truncates the file before writing. A crash or power loss mid-write leaves a partial JSON file. Now uses tempfile.mkstemp + os.replace for atomic writes, matching the pattern used in _utils.py, shared_infra.py, and other safe-write utilities in the codebase.
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Pull request overview
Makes event configuration JSON writes atomic using a temporary file and os.replace.
Changes:
- Writes JSON to a same-directory temporary file.
- Cleans up temporary files on failure.
Show a summary per file
| File | Description |
|---|---|
src/specify_cli/events.py |
Adds atomic JSON replacement logic. |
Review details
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Suppressed comments (1)
src/specify_cli/events.py:2024
mkstempcreates the staged file with mode0600, andos.replaceswaps that inode over the existing config. Unlike the previouswrite_textcall, this silently changes permissions (and potentially ownership) on every merge, which can lock other users or processes out of shared0640/0644config files. Preserve the existing file metadata before replacing it, as the atomic writer insrc/specify_cli/_utils.py:163-193does.
os.replace(tmp, dst)
- Files reviewed: 1/1 changed files
- Comments generated: 1
- Review effort level: Balanced
| with os.fdopen(fd, "w", encoding="utf-8") as f: | ||
| json.dump(data, f, indent=2) | ||
| f.write("\n") | ||
| os.replace(tmp, dst) |
mnriem
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Aug 13, 2026
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Problem
Despite its name, _safe_write_json used write_text() which truncates the file before writing. A crash or power loss mid-write leaves a partial JSON file. This function is called by _merge_copilot_json, _merge_opencode_plugin_ref, etc., meaning all Copilot and OpenCode event config writes were non-atomic.
Fix
Now uses empfile.mkstemp + os.replace for atomic writes, matching the pattern used in _utils.py, shared_infra.py, and other safe-write utilities in the codebase.