microsoft/cpprestsdk

utility::conversions::latin1_to_utf16 - Is there a bug for characters above 0x80?

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#101 建立於 2016年3月23日

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描述

I've tried to use utility::conversions::latin1_to_utf16 to convert latin1 string to UTF-16. The string contained 'í' character (0xed). After converting it should become 0x00ed but it seems that converting method replaced it with 0xffed.

I think this may be result of casting signed char to utf16char and dest[i] = utf16char(s[i]); in asyncrt_utils.cpp should be replaced by dest[i] = utf16char(static_cast<unsigned char>(s[i])); to fix it. Can someone check if I'm right?

貢獻者指南

技術棧
cpp
領域
apibackend
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
2
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
under 1 hour
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
basic C++ knowledgeunderstanding of signed/unsigned char
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
70
研究方向
The issue identifies a potential bug in `asyncrt utils.cpp` in the `utility::conversions::latin1 to utf16` function. The problem is that casting a signed `char` to `utf16char` (likely `unsigned short`) causes sign extension for characters above 0x80, resulting in incorrect values like 0xFFED instead of 0x00ED. The suggested fix is to use `static cast<unsigned char>` before casting to `utf16char`. To confirm, examine the source file `asyncrt utils.cpp` in the repository and test the conversion with a Latin 1 character like 'í' (0xED). The maintainer should verify the fix and ensure it doesn't break other use cases.