1 files changed, 20 insertions, 1 deletions
diff --git a/src/util.h b/src/util.h
index af3ef0b46..a2233a7e8 100644
--- a/src/util.h
+++ b/src/util.h
@@ -306,11 +306,30 @@ int git__date_parse(git_time_t *out, const char *date);
 
 /*
  * Unescapes a string in-place.
- * 
+ *
  * Edge cases behavior:
  * - "jackie\" -> "jacky\"
  * - "chan\\" -> "chan\"
  */
 extern size_t git__unescape(char *str);
 
+/*
+ * Swap a pointer with thread safety, returning old value.
+ */
+GIT_INLINE(void *) git__swap(git_mutex *lock, void **ptr_ptr, void *new_ptr)
+{
+	void *old_ptr;
+
+	if (*ptr_ptr == new_ptr)
+		return NULL;
+	if (git_mutex_lock(lock) < 0)
+		return new_ptr;
+
+	old_ptr = *ptr_ptr;
+	*ptr_ptr = new_ptr;
+
+	git_mutex_unlock(lock);
+	return old_ptr;
+}
+
 #endif /* INCLUDE_util_h__ */