Fix UTF-8 boundary issues in mysql_top_level_limit, parse_usize_token,
and mysql_keyword_at functions that caused crashes when SQL contains
Chinese characters in string literals.
The issue was introduced in commit 021e1682 which added byte-level
indexing without proper UTF-8 boundary checks. When parsing SQL with
Chinese text (e.g., \"WHERE name LIKE '%批量保存%'\"), the byte index
could point to the middle of a multi-byte UTF-8 character, causing
Rust to panic when slicing the string.
Changes:
- parse_usize_token: Use std::str::from_utf8 to validate slice before parsing
- mysql_keyword_at: Add is_char_boundary checks for safe string slicing
- mysql_top_level_limit: Skip non-UTF-8-boundary bytes after incrementing index
This ensures all byte-level indexing operations stay on valid UTF-8 boundaries,
preventing panics while maintaining the original functionality of detecting
LIMIT clauses for bounded result set collection.
Fixes crash reported by users when executing queries with Chinese conditions.
bigliangzao
7643148708