fix: validate Unicode codepoints in utf8_encode()#4
Merged
mitchellh merged 1 commit intoMar 23, 2026
Conversation
The Unicode standard defines the maximum valid codepoint as U+10FFFF. Codepoints above this value are invalid and produce malformed UTF-8 sequences. This patch adds validation to replace out-of-range codepoints with the Unicode replacement character U+FFFD. This follows RFC 3629 which restricted UTF-8 to encode no more than U+10FFFF to avoid UTF-16 surrogate pairs and maintain consistency with the Unicode standard. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
utf8_encode()to ensure codepoints are within valid Unicode range (U+0000 to U+10FFFF)Details
The Unicode standard defines the maximum valid codepoint as U+10FFFF (RFC 3629). The current
utf8_encode()function accepts any 32-bit value >= 0x10000 and encodes it as 4-byte UTF-8, which can produce invalid sequences for values > 0x10FFFF.This fix validates the input codepoint and replaces out-of-range values with U+FFFD () before encoding, ensuring the output is always valid UTF-8.
Test plan
🤖 Generated with Claude Code