binman: Support updating entries in an existing image

While it is useful and efficient to build images in a single pass from a
unified description, it is sometimes desirable to update the image later.

Add support for replace an existing file with one of the same size. This
avoids needing to repack the file. Support for more advanced updates will
come in future patches.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/image.py

@@ -10,6 +10,7 @@ from __future__ import print_function
 from collections import OrderedDict
 import fnmatch
 from operator import attrgetter
+import os
 import re
 import sys
 
@@ -96,6 +97,8 @@ class Image(section.Entry_section):
         image.fdtmap_dtb = dtb
         image.fdtmap_data = fdtmap_data
         image._data = data
+        image._filename = fname
+        image.image_name, _ = os.path.splitext(fname)
         return image
 
     def Raise(self, msg):