[Bug 54857] New: Gecko engine initialization changes current C run-time locale

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=54857

Bug ID: 54857
           Summary: Gecko engine initialization changes current C run-time
                    locale
           Product: Wine
           Version: 8.6
          Hardware: x86-64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: mshtml
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

The application that I have here crashes after the call
ucrtbase._strupr("SOME STRING")
Accoring to dlls/msvcrt/string.c _strupr() implementation avoids writing to the
source buffer if the buffer contains upper case characters and current locale
is "C". dlls/msvcrt/tests/string.c,test__strupr() contains a test case that
confirms this behaviour.

According to the logs before calling ucrtbase._strupr("SOME STRING")
application loads mshtml.dll, then xul.dll gets loaded which during its
initialization calls ucrtbase.setlocale(0, ""), and that leads to the current C
locale change.

I've created a test case that replicates this behaviour, and under Windows the
test completes successfully, however under Wine it crashes. Adding a call to
setlocale(0, "") also makes the test crash under Windows, so Wine
implementation of _strupr() appears to be correct.

A possible solution is to save current locale before xul.dll initialization and
later restore the locale.

I'll attach a test case and a patch with proposed solution to this bug report.