lib: replace _tcsncpy/wcsncpy/wcscpy with _s counterparts (Windows)

Replace:
- curl_sspi: macro `_tcsncpy()` with `_tcsncpy_s()`.
- curlx/fopen: `wcsncpy()` with `wcsncpy_s()`.
- curlx/fopen: `wcscpy()` with `wcscpy_s()`.

Use of the pre-existing functions were safe. This patch aims to use the
recommended Windows CRT functions. Handle errors returned by them. Also
to avoid the compiler warnings silenced via `_CRT_SECURE_NO_WARNINGS`:

```
lib/curl_sspi.c(152): warning C4996: 'wcsncpy': This function or variable may be unsafe. Consider using wcsncpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
lib/curlx/fopen.c(161): warning C4996: 'wcsncpy': This function or variable may be unsafe. Consider using wcsncpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
lib/curlx/fopen.c(162): warning C4996: 'wcscpy': This function or variable may be unsafe. Consider using wcscpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
lib/curlx/fopen.c(174): warning C4996: 'wcsncpy': This function or variable may be unsafe. Consider using wcsncpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
lib/curlx/fopen.c(175): warning C4996: 'wcscpy': This function or variable may be unsafe. Consider using wcscpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
```

Refs:
https://learn.microsoft.com/cpp/c-runtime-library/reference/strncpy-strncpy-l-wcsncpy-wcsncpy-l-mbsncpy-mbsncpy-l
https://learn.microsoft.com/cpp/c-runtime-library/reference/strncpy-s-strncpy-s-l-wcsncpy-s-wcsncpy-s-l-mbsncpy-s-mbsncpy-s-l
https://learn.microsoft.com/cpp/c-runtime-library/security-features-in-the-crt

Cherry-picked from #19581 (in part)
Closes #19589
This commit is contained in:
Viktor Szakats 2025-11-17 23:49:15 +01:00
parent 3561f2c7bf
commit eaa7651374
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3 changed files with 22 additions and 7 deletions

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@ -98,7 +98,7 @@
#define _CRT_SECURE_NO_WARNINGS /* for __sys_errlist, __sys_nerr, _open(),
_wfopen(), _wopen(), fopen(), freopen(),
getenv(), gmtime(), mbstowcs(), sprintf(),
strcpy(), wcscpy(), wcsncpy(), wcstombs(),
strcpy(), wcstombs(),
in tests: localtime(), open(), sscanf() */
#endif
#endif /* _MSC_VER */