binman: Add a control for post-pack entry expansion

We plan to support changing the size of entries after they have been
packed. For now it will always be enabled. But to aid testing of both
cases (in the event that we want to add a command-line flag, for example),
add a setting to control it.

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

tools/binman/state.py

@@ -31,6 +31,11 @@ fdt_subset = set()
 # The DTB which contains the full image information
 main_dtb = None
 
+# Allow entries to expand after they have been packed. This is detected and
+# forces a re-pack. If not allowed, any attempted expansion causes an error in
+# Entry.ProcessContentsUpdate()
+allow_entry_expansion = True
+
 def GetFdt(fname):
     """Get the Fdt object for a particular device-tree filename
 
@@ -250,3 +255,22 @@ def CheckSetHashValue(node, get_data_func):
             data = m.digest()
         for n in GetUpdateNodes(hash_node):
             n.SetData('value', data)
+
+def SetAllowEntryExpansion(allow):
+    """Set whether post-pack expansion of entries is allowed
+
+    Args:
+       allow: True to allow expansion, False to raise an exception
+    """
+    global allow_entry_expansion
+
+    allow_entry_expansion = allow
+
+def AllowEntryExpansion():
+    """Check whether post-pack expansion of entries is allowed
+
+    Returns:
+        True if expansion should be allowed, False if an exception should be
+            raised
+    """
+    return allow_entry_expansion