macro_collector: be stricter about unusual macros

When looking for constructors, do complain if we see an unusual macro with a
parameter: there's a significant chance that it's something new that will
require specific handling. As a consequence, we need to explicitly skip more
things that are known not to be constructors.

Keep ignoring macros without parameters that don't look like constructors
for the types we care about. Those probably don't matter.

Signed-off-by: Gilles Peskine <[email protected]>

scripts/mbedtls_framework/macro_collector.py

@@ -279,12 +279,27 @@ class PSAMacroCollector(PSAMacroEnumerator):
                                       r'(.+)')
     _deprecated_definition_re = re.compile(r'\s*MBEDTLS_DEPRECATED')
 
+    # Macro that is a destructor, not a constructor (i.e. takes a thing as
+    # an argument and analyzes it, rather than constructing a thing).
+    _destructor_name_re = re.compile(r'.*(_GET_|_IS_)|.*_LENGTH\Z')
+
+    # Macro that converts between things, rather than building a thing from
+    # scratch.
+    _conversion_macro_names = frozenset([
+        'PSA_KEY_TYPE_KEY_PAIR_OF_PUBLIC_KEY',
+        'PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR',
+        'PSA_ALG_FULL_LENGTH_MAC',
+        'PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG',
+        'PSA_JPAKE_EXPECTED_INPUTS',
+        'PSA_JPAKE_EXPECTED_OUTPUTS',
+    ])
+
     def read_line(self, line):
         """Parse a C header line and record the PSA identifier it defines if any.
         This function analyzes lines that start with "#define PSA_"
         (up to non-significant whitespace) and skips all non-matching lines.
         """
-        # pylint: disable=too-many-branches
+        # pylint: disable=too-many-branches,too-many-return-statements
         m = re.match(self._define_directive_re, line)
         if not m:
             return
@@ -297,6 +312,12 @@ class PSAMacroCollector(PSAMacroEnumerator):
             # backward compatibility aliases that share
             # numerical values with non-deprecated values.
             return
+        if re.match(self._destructor_name_re, name):
+            # Not a constructor
+            return
+        if name in self._conversion_macro_names:
+            # Not a constructor
+            return
         if self.is_internal_name(name):
             # Macro only to build actual values
             return
@@ -324,9 +345,13 @@ class PSAMacroCollector(PSAMacroEnumerator):
             self.algorithms_from_hash[name] = self.algorithm_tester(name)
         elif name.startswith('PSA_KEY_USAGE_') and not parameter:
             self.key_usage_flags.add(name)
-        else:
-            # Other macro without parameter
+        elif parameter is None:
+            # Macro with no parameter, whose name does not start with one
+            # of the prefixes we look for. Just ignore it.
             return
+        else:
+            raise Exception("Unsupported macro and parameter name: {}({})"
+                            .format(name, parameter))
 
     _nonascii_re = re.compile(rb'[^\x00-\x7f]+')
     _continued_line_re = re.compile(rb'\\\r?\n\Z')