binman: Avoid needing the section size in advance

Entries which include a section and need to obtain its contents call
GetData(), as with any other entry. But the current implementation of this
method in entry_Section requires the size of the section to be known. If
it is unknown, an error is produced, since size is None:

   TypeError: can't multiply sequence by non-int of type 'NoneType'

There is no need to know the size in advance since the code can be
adjusted to build up the section piece by piece, instead of patching each
entry into an existing bytearray.

Update the code to handle this and add a test.
Signed-off-by: NSimon Glass <sjg@chromium.org>

tools/binman/etype/section.py

@@ -142,13 +142,19 @@ class Entry_section(Entry):
         return self.GetEntryContents()
 
     def GetData(self):
-        section_data = tools.GetBytes(self._pad_byte, self.size)
+        section_data = b''
 
         for entry in self._entries.values():
             data = entry.GetData()
-            base = self.pad_before + entry.offset - self._skip_at_start
-            section_data = (section_data[:base] + data +
-                            section_data[base + len(data):])
+            base = self.pad_before + (entry.offset or 0) - self._skip_at_start
+            pad = base - len(section_data)
+            if pad > 0:
+                section_data += tools.GetBytes(self._pad_byte, pad)
+            section_data += data
+        if self.size:
+            pad = self.size - len(section_data)
+            if pad > 0:
+                section_data += tools.GetBytes(self._pad_byte, pad)
         self.Detail('GetData: %d entries, total size %#x' %
                     (len(self._entries), len(section_data)))
         return section_data

tools/binman/ftest.py

@@ -3321,6 +3321,12 @@ class TestFunctional(unittest.TestCase):
         expected4 = sym_values + U_BOOT_TPL_DATA[16:]
         self.assertEqual(expected4, data[upto3:])
 
+    def testPackX86RomIfwiSectiom(self):
+        """Test that a section can be placed in an IFWI region"""
+        self._SetupIfwi('fitimage.bin')
+        data = self._DoReadFile('151_x86_rom_ifwi_section.dts')
+        self._CheckIfwi(data)
+
 
 if __name__ == "__main__":
     unittest.main()

tools/binman/test/151_x86_rom_ifwi_section.dts

+// SPDX-License-Identifier: GPL-2.0+
+
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		sort-by-offset;
+		end-at-4gb;
+		size = <0x800000>;
+		intel-descriptor {
+			filename = "descriptor.bin";
+		};
+
+		intel-ifwi {
+			offset-unset;
+			filename = "fitimage.bin";
+			convert-fit;
+
+			section {
+				ifwi-replace;
+				ifwi-subpart = "IBBP";
+				ifwi-entry = "IBBL";
+				u-boot-tpl {
+				};
+				u-boot-dtb {
+				};
+			};
+		};
+	};
+};