GeezerVison is showing github.com — Add `PyOS_vsnprintf` & `PyOS_snprintf` to the capi by bschoenmaeckers · Pull Request #9409 · RustPython/RustPython
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bschoenmaeckers
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Oct 27, 2026
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Summary
Summary by CodeRabbit
- New Features
- Added formatted-output APIs for applications using the C interface, including support for both variadic and pre-prepared argument lists.
- Output can be written to a caller-provided buffer with a specified size, making these APIs available for bounded string formatting.
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bschoenmaeckers
changed the title
Add PyOS_vsnprintf % PyOS_snprintf to the capi
Add PyOS_vsnprintf & PyOS_snprintf to the capi
Oct 27, 2026
Codex Review Summary
This comment shows the latest Codex review activity on this pull request.
| Review |
Status |
Commit |
Review trigger |
| 📝 Code Review |
✅ Completed 2026-10-27T15:56:48.235009Z |
5b6a5cc |
PR opened |
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coderabbitai
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Oct 27, 2026
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No actionable comments were generated in the recent review.
Recent review info
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Run configuration
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Commits
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Reviewing files that changed from the base of the PR and between b25ab5e and 5b6a5cc.
Files selected for processing: 1
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crates/capi/src/pyerrors.rs
Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 8 remain after this review.
Walkthrough
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This change adds PyOS_snprintf and PyOS_vsnprintf to the C API. The variadic function forwards its arguments to the va_list function, which calls vsnprintf when the size is within the supported limit.
Changes: Formatted string output API
| Layer / File(s) |
Summary |
Add snprintf wrappers crates/capi/src/pyerrors.rs |
Adds PyOS_snprintf and PyOS_vsnprintf. The latter returns -666 when size exceeds c_int::MAX - 1. When size > 0 and the destination is non-null, it writes a terminating NUL at str[size - 1]. |
Priority: Normal
Estimated code review effort: 2 (Simple) | ~10 minutes
Change: Feature
Suggested reviewers: youknowone
Merge Risk: Minimal · up to 5b6a5
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No merge-blocking risk is established; normal build and test checks remain appropriate.
Pre-merge checks: 4 · 1
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Failed checks: 1 warning
| Check name |
Status |
Explanation |
Resolution |
| Docstring Coverage |
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Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within survi… |
Write docstrings for the functions missing them to satisfy the coverage threshold. |
Passed checks: 4 passed
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| Check name |
Status |
Explanation |
| Description Check |
 |
Check skipped - CodeRabbit’s high-level summary is enabled. |
| Title check |
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The title names the two C APIs the PR adds, PyOS_vsnprintf and PyOS_snprintf, and the raw summary confirms both are added to crates/capi/src/pyerrors.rs. The title matches the main change and the comm… |
| Linked Issues check |
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Check skipped because no linked issues were found for this pull request. |
| Out of Scope Changes check |
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Check skipped because no linked issues were found for this pull request. |
Full details: Title check
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Explanation
The title names the two C APIs the PR adds, PyOS_vsnprintf and PyOS_snprintf, and the raw summary confirms both are added to crates/capi/src/pyerrors.rs. The title matches the main change and the commit message.
Full details: Docstring Coverage
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Explanation
Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 2 functions across 1 files.
Resolution
Write docstrings for the functions missing them to satisfy the coverage threshold.
Finishing Touches
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🧪 Generate unit tests (beta)
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- Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts
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