[glib: 1/2] win32: Check and avoid using TLS index 0

[Philip Withnall <pwithnall src gnome org>]

commit 3364e0204150a7f38771a44dc46d4a1fc7084cdd
Author: Yongsu Park <pcpenpal gmail com>
Date:   Wed May 13 17:29:13 2020 +0900

    win32: Check and avoid using TLS index 0
    
    Zero is a valid TLS index so it needs to be checked. It’s also the
    integer used to indicate that no TLS has been allocated yet, so it can’t
    be used as a TLS identifier.
    
    Incorporates changes from Philip Withnall.
    
    Fixes: #2058

 glib/gthread-win32.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)
---
diff --git a/glib/gthread-win32.c b/glib/gthread-win32.c
index 66558df4a..63e3cdd76 100644
--- a/glib/gthread-win32.c
+++ b/glib/gthread-win32.c
@@ -319,7 +319,17 @@ g_private_get_impl (GPrivate *key)
 
           impl = TlsAlloc ();
 
-          if (impl == TLS_OUT_OF_INDEXES)
+          if G_UNLIKELY (impl == 0)
+            {
+              /* Ignore TLS index 0 temporarily (as 0 is the indicator that we
+               * haven't allocated TLS yet) and alloc again;
+               * See https://gitlab.gnome.org/GNOME/glib/-/issues/2058 */
+              DWORD impl2 = TlsAlloc ();
+              TlsFree (impl);
+              impl = impl2;
+            }
+
+          if (impl == TLS_OUT_OF_INDEXES || impl == 0)
             g_thread_abort (0, "TlsAlloc");
 
           if (key->notify != NULL)