binman: Add length header attribute to dtb entry

Add an optional length header attribute to the device tree blob entry
class based on the compressed data header from the utilities to compress
and decompress data.

If needed the header could be enabled with the following
attribute beside the compress attribute:
  prepend = "length";

The header was introduced as part of commit eb0f4a4cb402 ("binman:
Support replacing data in a cbfs") to allow device tree entries to be
larger than the compressed contents. Regarding the commit "this is
necessary to cope with a compressed device tree being updated in such a
way that it shrinks after the entry size is already set (an obscure
case)". This case need to be fixed without influence any compressed data
by itself.

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 39 insertions, 0 deletions

diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index 9bce102e77b..7a3e4f8ae0b 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -5807,6 +5807,45 @@ fdt         fdtmap                Extract the devicetree blob from the fdtmap
         expect = U_BOOT_SPL_DATA + U_BOOT_DATA
         self.assertEqual(expect, data[:len(expect)])
 
+    def testCompressDtbPrependInvalid(self):
+        """Test that invalid header is detected"""
+        with self.assertRaises(ValueError) as e:
+            self._DoReadFileDtb('235_compress_dtb_prepend_invalid.dts')
+        self.assertIn("Node '/binman/u-boot-dtb': Invalid prepend in "
+                      "'u-boot-dtb': 'invalid'", str(e.exception))
+
+    def testCompressDtbPrependLength(self):
+        """Test that compress with length header works as expected"""
+        data = self._DoReadFileRealDtb('236_compress_dtb_prepend_length.dts')
+        image = control.images['image']
+        entries = image.GetEntries()
+        self.assertIn('u-boot-dtb', entries)
+        u_boot_dtb = entries['u-boot-dtb']
+        self.assertIn('fdtmap', entries)
+        fdtmap = entries['fdtmap']
+
+        image_fname = tools.get_output_filename('image.bin')
+        orig = control.ReadEntry(image_fname, 'u-boot-dtb')
+        dtb = fdt.Fdt.FromData(orig)
+        dtb.Scan()
+        props = self._GetPropTree(dtb, ['size', 'uncomp-size'])
+        expected = {
+            'u-boot:size': len(U_BOOT_DATA),
+            'u-boot-dtb:uncomp-size': len(orig),
+            'u-boot-dtb:size': u_boot_dtb.size,
+            'fdtmap:size': fdtmap.size,
+            'size': len(data),
+            }
+        self.assertEqual(expected, props)
+
+        # Check implementation
+        self.assertEqual(U_BOOT_DATA, data[:len(U_BOOT_DATA)])
+        rest = data[len(U_BOOT_DATA):]
+        comp_data_len = struct.unpack('<I', rest[:4])[0]
+        comp_data = rest[4:4 + comp_data_len]
+        orig2 = self._decompress(comp_data)
+        self.assertEqual(orig, orig2)
+
 
 if __name__ == "__main__":
     unittest.main()