Fix for #617

Author: rfm

ChangeLog

@@ -1,3 +1,9 @@
+2026-06-16 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSLog.m: Fix race condition in lock setup reported by
+	DTW-Thalion.  Set up cached methods for lock before setting the
+	variable itself.
+
 2026-06-13 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Headers/GNUstepBase/GSObjCRuntime.h:

Source/NSLog.m

@@ -99,16 +99,22 @@
 NSRecursiveLock *
 GSLogLock()
 {
-  if (myLock == nil)
+  if (nil == myLock)
     {
       static gs_mutex_t	setupLock = GS_MUTEX_INIT_STATIC;
 
       GS_MUTEX_LOCK(setupLock);
-      if (myLock == nil)
+      if (nil == myLock)
 	{
-	  myLock = [NSRecursiveLock new];
-          lockImp = [myLock methodForSelector: @selector(lock)];
-          unlockImp = [myLock methodForSelector: @selector(unlock)];
+	  NSRecursiveLock	*tmp;
+
+	  /* Avoid race condition by caching method implementations
+	   * before setting value in myLock 
+	   */
+	  tmp = [NSRecursiveLock new];
+          lockImp = [tmp methodForSelector: @selector(lock)];
+          unlockImp = [tmp methodForSelector: @selector(unlock)];
+	  myLock = tmp;
 	}
       GS_MUTEX_UNLOCK(setupLock);
     }