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fix(cli): readStdin uses string.length instead of byte length for size limits #23417
Description
Bug
readStdin() in packages/cli/src/utils/readStdin.ts defines the stdin size limit as 8 * 1024 * 1024 (8 MB in bytes), but enforces it using string.length after process.stdin.setEncoding('utf8').
Root cause
process.stdin.setEncoding('utf8');
if (totalSize + chunk.length > MAX_STDIN_SIZE) {
const remainingSize = MAX_STDIN_SIZE - totalSize;
data += chunk.slice(0, remainingSize);
}string.lengthcounts UTF-16 code units, not UTF-8 bytes- multi-byte characters (e.g., CJK, emoji) are undercounted
string.slice()may split surrogate pairs, producing malformed output
Impact
- The 8 MB limit is not byte-accurate for non-ASCII input
- Truncation may corrupt characters at the boundary
Suggested fix
- Use
Buffer.byteLength(chunk, 'utf8')for byte-accurate size tracking - Use a byte-safe truncation method (e.g., via
Buffer) to avoid splitting multi-byte characters - Align implementation with the approach used in
readStdinLines.ts(PR feat(cli): allow -i/--prompt-interactive with piped stdin #23414)
Scope
This issue applies to:
packages/cli/src/utils/readStdin.ts
Note:
readStdinLines.ts was addressed separately in PR #23414.
Activity
gemini-cli commentedon Mar 23, 2026
Found possible duplicate issues:
If you believe this is not a duplicate, please remove the
status/possible-duplicatelabel.GoBeromsu commentedon Mar 23, 2026
Clarification: this is not a duplicate.
I previously opened #23537 for the same root cause, and merged it into this issue (#23417) to keep tracking in one place. #23537 is now closed as part of that consolidation.
Additionally:
readStdinLines.tswas already fixed in PR feat(cli): allow -i/--prompt-interactive with piped stdin #23414readStdin.tsI’ve updated the issue description accordingly and will follow up with a PR.
devr0306 commentedon Apr 27, 2026
Triage Summary
@GoBeromsu, thank you for identifying this byte-accuracy bug in
readStdin. Since you've indicated you're working on a PR to align it with thereadStdinLinesfix, I've marked this ashelp wanted.