fix(cli): use byte length instead of string length for readStdin size limits by Adib234 · Pull Request #26224 · google-gemini/gemini-cli

Adib234 · 2026-04-29T20:28:51Z

Summary

Fixes the size limitation logic in readStdin() to use byte length instead of string length. This ensures that the 8MB limit is accurately enforced for multi-byte characters (e.g., CJK characters, emojis) and prevents data corruption caused by splitting multi-byte characters at the truncation boundary.

Details

Replaced chunk.length with Buffer.byteLength(chunk, 'utf8') for accurate byte tracking.
Implemented truncateUtf8Bytes utility to safely truncate UTF-8 strings at a byte limit without splitting multi-byte characters (continuation bytes).
Aligned the implementation with the approach used in readStdinLines.ts (from PR feat(cli): allow -i/--prompt-interactive with piped stdin #23414).

Related Issues

Fixes #23417

How to Validate

Run unit tests for readStdin:

npm test -w @google/gemini-cli -- src/utils/readStdin.test.ts

The new tests verify:
- Truncation of 3-byte characters (e.g., '한') happens at a valid byte boundary (result size is a multiple of 3).
- The string length can exceed the 8MB limit if characters were 1-byte, but for 3-byte characters, it correctly truncates earlier.
- No replacement characters (\uFFFD) are present in the output.

Pre-Merge Checklist

… limits

gemini-code-assist · 2026-04-29T20:29:02Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical issue in the CLI's stdin processing where size limits were incorrectly calculated using string length instead of byte length. By implementing a robust truncation utility and switching to byte-based tracking, the changes prevent potential data corruption when handling multi-byte characters like emojis or CJK scripts, ensuring the 8MB limit is accurately and safely enforced.

Highlights

Accurate Byte Tracking: Updated the stdin reading logic to use Buffer.byteLength instead of string length, ensuring the 8MB limit is enforced based on actual byte size rather than character count.
Safe Truncation: Introduced a truncateUtf8Bytes utility to prevent data corruption by ensuring multi-byte UTF-8 characters are not split at the truncation boundary.
Enhanced Testing: Added unit tests to verify correct truncation behavior for multi-byte characters and confirm that the byte limit is strictly respected.

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github-actions · 2026-04-29T20:33:41Z

Size Change: +341 B (0%)

Total Size: 33.9 MB

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_{compressed-size-action}

gemini-code-assist

Code Review

This pull request improves the handling of standard input truncation by switching from character-based length to byte-based length. It introduces a truncateUtf8Bytes utility to ensure that multi-byte UTF-8 characters are not split at the truncation boundary, preventing data corruption or invalid characters. New unit tests verify the correct truncation of multi-byte characters and the enforcement of the 8MB byte limit. I have no feedback to provide.

… limits (google-gemini#26224)

fix(cli): use byte length instead of string length for readStdin size…

4203ef7

… limits

Adib234 requested a review from a team as a code owner April 29, 2026 20:28

gemini-code-assist Bot reviewed Apr 29, 2026

View reviewed changes

gemini-cli Bot added the area/core Issues related to User Interface, OS Support, Core Functionality label Apr 29, 2026

cocosheng-g approved these changes Apr 30, 2026

View reviewed changes

cocosheng-g added this pull request to the merge queue Apr 30, 2026

Merged via the queue into main with commit 487fb21 Apr 30, 2026
49 of 50 checks passed

cocosheng-g deleted the fix/issue-23417-read-stdin-byte-length branch April 30, 2026 14:29

TirthNaik-99 pushed a commit to TirthNaik-99/gemini-cli that referenced this pull request May 4, 2026

fix(cli): use byte length instead of string length for readStdin size…

9ed9ce1

… limits (google-gemini#26224)

kimjune01 pushed a commit to kimjune01/gemini-cli-claude that referenced this pull request May 6, 2026

fix(cli): use byte length instead of string length for readStdin size…

f3c28f7

… limits (google-gemini#26224)

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fix(cli): use byte length instead of string length for readStdin size limits#26224
cocosheng-g merged 1 commit intomainfrom
fix/issue-23417-read-stdin-byte-length

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Adib234 commented Apr 29, 2026

Summary

Details

Related Issues

How to Validate

Pre-Merge Checklist

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gemini-code-assist Bot commented Apr 29, 2026

Summary of Changes

Highlights

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