binman: Support shrinking a entry after packing

Sometimes an entry may shrink after it has already been packed. In that
case we must repack the items. Of course it is always possible to just
leave the entry at its original size and waste space at the end. This is
what binman does by default, since there is the possibility of the entry
changing size every time binman calculates its contents, thus causing a
loop.

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

1 files changed, 24 insertions, 1 deletions

diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index f8568d7cda1..11155ced709 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -2143,7 +2143,7 @@ class TestFunctional(unittest.TestCase):
         """Test expanding an entry after it is packed, twice"""
         with self.assertRaises(ValueError) as e:
             self._DoReadFile('122_entry_expand_twice.dts')
-        self.assertIn("Image '/binman': Entries expanded after packing",
+        self.assertIn("Image '/binman': Entries changed size after packing",
                       str(e.exception))
 
     def testEntryExpandSection(self):
@@ -2952,6 +2952,29 @@ class TestFunctional(unittest.TestCase):
         self.assertIn('Entry data size does not match, but allow-repack is not present for this image',
                       str(e.exception))
 
+    def testEntryShrink(self):
+        """Test contracting an entry after it is packed"""
+        try:
+            state.SetAllowEntryContraction(True)
+            data = self._DoReadFileDtb('140_entry_shrink.dts',
+                                       update_dtb=True)[0]
+        finally:
+            state.SetAllowEntryContraction(False)
+        self.assertEqual(b'a', data[:1])
+        self.assertEqual(U_BOOT_DATA, data[1:1 + len(U_BOOT_DATA)])
+        self.assertEqual(b'a', data[-1:])
+
+    def testEntryShrinkFail(self):
+        """Test not being allowed to contract an entry after it is packed"""
+        data = self._DoReadFileDtb('140_entry_shrink.dts', update_dtb=True)[0]
+
+        # In this case there is a spare byte at the end of the data. The size of
+        # the contents is only 1 byte but we still have the size before it
+        # shrunk.
+        self.assertEqual(b'a\0', data[:2])
+        self.assertEqual(U_BOOT_DATA, data[2:2 + len(U_BOOT_DATA)])
+        self.assertEqual(b'a\0', data[-2:])
+
 
 if __name__ == "__main__":
     unittest.main()