bitbake: utils: add umask changing context manager

Add a umask context manager which can be used to temporarily change the
umask in a 'with' block.

(Bitbake rev: 6ca998054e422da72c7906d3ec4f204d88c32ee0)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

bitbake/lib/bb/utils.py

@@ -969,6 +969,17 @@ def which(path, item, direction = 0, history = False, executable=False):
         return "", hist
     return ""
 
+@contextmanager
+def umask(new_mask):
+    """
+    Context manager to set the umask to a specific mask, and restore it afterwards.
+    """
+    current_mask = os.umask(new_mask)
+    try:
+        yield
+    finally:
+        os.umask(current_mask)
+
 def to_boolean(string, default=None):
     if not string:
         return default