binman: Tidy up the vblock entry

At present if there are two vblock entries an image their contents are
written to the same file in the output directory. This prevents checking
the contents of each separately.

Fix this by adding part of the entry path to the filename, and add some
missing comments.

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

tools/binman/README.entries

@@ -546,6 +546,11 @@ Properties / Entry arguments:
     - kernelkey: Name of the kernel key to use (inside keydir)
     - preamble-flags: Value of the vboot preamble flags (typically 0)
 
+Output files:
+    - input.<unique_name> - input file passed to futility
+    - vblock.<unique_name> - output file generated by futility (which is
+        used as the entry contents)
+
 Chromium OS signs the read-write firmware and kernel, writing the signature
 in this block. This allows U-Boot to verify that the next firmware stage
 and kernel are genuine.

tools/binman/entry.py

@@ -456,3 +456,21 @@ features to produce new behaviours.
         if missing:
             raise ValueError('Documentation is missing for modules: %s' %
                              ', '.join(missing))
+
+    def GetUniqueName(self):
+        """Get a unique name for a node
+
+        Returns:
+            String containing a unique name for a node, consisting of the name
+            of all ancestors (starting from within the 'binman' node) separated
+            by a dot ('.'). This can be useful for generating unique filesnames
+            in the output directory.
+        """
+        name = self.name
+        node = self._node
+        while node.parent:
+            node = node.parent
+            if node.name == 'binman':
+                break
+            name = '%s.%s' % (node.name, name)
+        return name

tools/binman/entry_test.py

@@ -54,6 +54,17 @@ class TestEntry(unittest.TestCase):
         self.assertIn("Unknown entry type 'invalid-name' in node "
                       "'invalid-path'", str(e.exception))
 
+    def testUniqueName(self):
+        """Test Entry.GetUniqueName"""
+        import entry
+        Node = collections.namedtuple('Node', ['name', 'parent'])
+        base_node = Node('root', None)
+        base_entry = entry.Entry(None, None, base_node, read_node=False)
+        self.assertEqual('root', base_entry.GetUniqueName())
+        sub_node = Node('subnode', base_node)
+        sub_entry = entry.Entry(None, None, sub_node, read_node=False)
+        self.assertEqual('root.subnode', sub_entry.GetUniqueName())
+
 
 if __name__ == "__main__":
     unittest.main()

tools/binman/etype/vblock.py

@@ -25,6 +25,11 @@ class Entry_vblock(Entry):
         - kernelkey: Name of the kernel key to use (inside keydir)
         - preamble-flags: Value of the vboot preamble flags (typically 0)
 
+    Output files:
+        - input.<unique_name> - input file passed to futility
+        - vblock.<unique_name> - output file generated by futility (which is
+            used as the entry contents)
+
     Chromium OS signs the read-write firmware and kernel, writing the signature
     in this block. This allows U-Boot to verify that the next firmware stage
     and kernel are genuine.
@@ -53,8 +58,9 @@ class Entry_vblock(Entry):
                 return False
             input_data += data
 
-        output_fname = tools.GetOutputFilename('vblock.%s' % self.name)
-        input_fname = tools.GetOutputFilename('input.%s' % self.name)
+        uniq = self.GetUniqueName()
+        output_fname = tools.GetOutputFilename('vblock.%s' % uniq)
+        input_fname = tools.GetOutputFilename('input.%s' % uniq)
         tools.WriteFile(input_fname, input_data)
         prefix = self.keydir + '/'
         args = [
@@ -69,6 +75,5 @@ class Entry_vblock(Entry):
         ]
         #out.Notice("Sign '%s' into %s" % (', '.join(self.value), self.label))
         stdout = tools.Run('futility', *args)
-        #out.Debug(stdout)
         self.SetContents(tools.ReadFile(output_fname))
         return True

tools/binman/ftest.py

@@ -1316,7 +1316,7 @@ class TestFunctional(unittest.TestCase):
         """Fake calls to the futility utility"""
         if pipe_list[0][0] == 'futility':
             fname = pipe_list[0][3]
-            with open(fname, 'w') as fd:
+            with open(fname, 'wb') as fd:
                 fd.write(VBLOCK_DATA)
             return command.CommandResult()