Use a custom implementation of wcsdup on Windows, so that malloc/free…

[Myriachan]

… overrides from curl_global_init are used for wcsdup correctly.

[Myriachan]

These overflow checks are probably unnecessary, because presumably the wchar string has a size fitting in size_t. I don't know what your standards are for checks like these.

[jay]

stdint may not be available and shouldn't be necessary. curl_setup defines SIZE_T_MAX, you can use that instead. Also Curl_wcsdup doesn't need so many lines, you can do a single check like
if(length > (SIZE_T_MAX / sizeof(wchar_t)) - 1)
return NULL;
return (wchar_t *)Curl_memdup(src, (length + 1) * sizeof(wchar_t))

[jay]

Ref: https://curl.se/mail/lib-2021-07/0056.html

[Myriachan]

stdint may not be available and shouldn't be necessary. curl_setup defines SIZE_T_MAX, you can use that instead. Also Curl_wcsdup doesn't need so many lines, you can do a single check like

Thanks! Didn't know about libcurl having a SIZE_T_MAX. Also, I didn't know how wordy the coding style should be.

[bagder]

Thanks!

[lukellmann]

_wcsdup is still used in the global_init function in easy.c. This means the wrong function will be used after reinitialisation after a full cleanup:

// sets 'Curl_cwcsdup' to '_wcsdup'
curl_global_init(CURL_GLOBAL_DEFAULT);
curl_global_cleanup();

// doesn't reset 'Curl_cwcsdup' to 'Curl_wcsdup', it's still '_wcsdup'
curl_global_init_mem(CURL_GLOBAL_DEFAULT, m, f, r, s, c);

[jay]

If you have found a bug in curl related to this PR then please open a new issue and explain how to reproduce