locale.c: Add mutex lock around _wsetlocale() call

The lock expands to nothing if unthreaded, or thread-local storage is in
effect.  But otherwise protects a global value from being clobbered by
another thread.

1 files changed, 4 insertions, 0 deletions

diff --git a/locale.c b/locale.c
index 93f97b1082..8c98b3269c 100644
--- a/locale.c
+++ b/locale.c
@@ -2609,14 +2609,18 @@ S_wrap_wsetlocale(pTHX_ const int category, const char *locale)
         }
     }
 
+    WSETLOCALE_LOCK;
     const wchar_t * wresult = _wsetlocale(category, wlocale);
     Safefree(wlocale);
 
     if (! wresult) {
+        WSETLOCALE_UNLOCK;
         return NULL;
     }
 
     const char * result = Win_wstring_to_utf8_string(wresult);
+    WSETLOCALE_UNLOCK;
+
     SAVEFREEPV(result); /* is there something better we can do here? */
 
     return result;