update tbox to fix tolower/toupper

[waruqi]

#7317

[gemini-code-assist]

Summary of Changes

Hello @waruqi, 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 primarily focuses on resolving issues with tolower and toupper string conversion functions by updating the tbox subproject. The update brings in necessary fixes from the dependency, ensuring more robust and accurate case transformations within the system.

Highlights

• tbox Subproject Update: The tbox subproject has been updated to a newer commit (ef851bcb6589b6092f5bd3fca4625631237f9bdd) from an older one (766ccfcbbdb28ed14a4a3e8babd573fc32a4d034).
• tolower/toupper Fix: This update is specifically intended to address and fix issues related to tolower and toupper functionality, improving string case conversion reliability.

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Changelog

• core/src/tbox/tbox
  • Updated the tbox subproject reference to a newer commit.
• core/src/xmake/string/lower.c
  • Removed an unnecessary blank line in the xm_string_lower function.

Activity

• No specific activity (comments, reviews, or progress updates) has been recorded for this pull request yet.

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[gemini-code-assist]

Code Review

This pull request updates the tbox submodule to fix issues with tolower and toupper functions. However, a critical security vulnerability has been identified: the xm_string_lower function in core/src/xmake/string/lower.c contains a heap-based buffer overflow. This is due to an incorrect assumption that lowercased UTF-8 strings will always fit within the same byte length as the original, which is not universally true for Unicode characters. Additionally, a minor whitespace cleanup was performed in core/src/xmake/string/lower.c.

[gemini-code-assist]

The buffer buffer is allocated with size + 1 bytes (line 55), which is sufficient for ASCII but not for all UTF-8 characters. Some characters can increase in byte length when converted to lowercase (e.g., Ⱥ (U+023A, 2 bytes) becomes ⱥ (U+2C65, 3 bytes)). The call to tb_charset_utf8_tolower(buffer, size) on line 61 does not take a capacity argument and will write past the end of the buffer if the resulting string is longer than the input. This is a heap-based buffer overflow.

To fix this, allocate a larger buffer that can accommodate the maximum possible growth (e.g., size * 2 + 1) or use a dynamic buffer.