binman: Add a return value to ProcessContentsUpdate()

At present if this function tries to update the contents such that the
size changes, it raises an error. We plan to add the ability to change
the size of entries after packing is completed, since in some cases it is
not possible to determine the size in advance.

An example of this is with a compressed device tree, where the values
of the device tree change in SetCalculatedProperties() or
ProcessEntryContents(). While the device tree itself does not change size,
since placeholders for any new properties have already bee added by
AddMissingProperties(), we cannot predict the size of the device tree
after compression. If a value changes from 0 to 0x1234 (say), then the
compressed device tree may expand.

As a first step towards supporting this, make ProcessContentsUpdate()
return a value indicating whether the content size is OK. For now this is
always True (since otherwise binman raises an error), but later patches
will adjust this.

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

1 files changed, 20 insertions, 2 deletions

diff --git a/tools/binman/entry.py b/tools/binman/entry.py
index b19a3b026f..7db1402b84 100644
--- a/tools/binman/entry.py
+++ b/tools/binman/entry.py
@@ -245,7 +245,8 @@ class Entry(object):
     def ProcessContentsUpdate(self, data):
         """Update the contents of an entry, after the size is fixed
 
-        This checks that the new data is the same size as the old.
+        This checks that the new data is the same size as the old. If the size
+        has changed, this triggers a re-run of the packing algorithm.
 
         Args:
             data: Data to set to the contents (bytes)
@@ -253,10 +254,12 @@ class Entry(object):
         Raises:
             ValueError if the new data size is not the same as the old
         """
+        size_ok = True
         if len(data) != self.contents_size:
             self.Raise('Cannot update entry size from %d to %d' %
                        (self.contents_size, len(data)))
         self.SetContents(data)
+        return size_ok
 
     def ObtainContents(self):
         """Figure out the contents of an entry.
@@ -401,7 +404,22 @@ class Entry(object):
         self.image_pos = image_pos + self.offset
 
     def ProcessContents(self):
-        pass
+        """Do any post-packing updates of entry contents
+
+        This function should call ProcessContentsUpdate() to update the entry
+        contents, if necessary, returning its return value here.
+
+        Args:
+            data: Data to set to the contents (bytes)
+
+        Returns:
+            True if the new data size is OK, False if expansion is needed
+
+        Raises:
+            ValueError if the new data size is not the same as the old and
+                state.AllowEntryExpansion() is False
+        """
+        return True
 
     def WriteSymbols(self, section):
         """Write symbol values into binary files for access at run time