Support an alternative prefix in psa_information.automatic_dependencies

No change to the generated files (the new code isn't used yet).

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

scripts/mbedtls_framework/crypto_data_tests.py

@@ -21,10 +21,8 @@ def psa_low_level_dependencies(*expressions: str) -> List[str]:
 
     This function generates MBEDTLS_PSA_BUILTIN_xxx symbols.
     """
-    high_level = psa_information.automatic_dependencies(*expressions)
-    for dep in high_level:
-        assert dep.startswith('PSA_WANT_')
-    return ['MBEDTLS_PSA_BUILTIN_' + dep[9:] for dep in high_level]
+    return psa_information.automatic_dependencies(*expressions,
+                                                  prefix='MBEDTLS_PSA_BUILTIN_')
 
 
 class HashPSALowLevel:

scripts/mbedtls_framework/psa_information.py

@@ -57,10 +57,16 @@ class Information:
         return constructors
 
 
-def psa_want_symbol(name: str) -> str:
-    """Return the PSA_WANT_xxx symbol associated with a PSA crypto feature."""
+def psa_want_symbol(name: str, prefix: Optional[str] = None) -> str:
+    """Return the PSA_WANT_xxx symbol associated with a PSA crypto feature.
+
+    You can use an altenative `prefix`, e.g. 'MBEDTLS_PSA_BUILTIN_'
+    when specifically testing builtin implementations.
+    """
+    if prefix is None:
+        prefix = 'PSA_WANT_'
     if name.startswith('PSA_'):
-        return name[:4] + 'WANT_' + name[4:]
+        return prefix + name[4:]
     else:
         raise ValueError('Unable to determine the PSA_WANT_ symbol for ' + name)
 
@@ -88,18 +94,23 @@ SYMBOLS_WITHOUT_DEPENDENCY = frozenset([
     'PSA_ALG_KEY_AGREEMENT', # chaining
     'PSA_ALG_TRUNCATED_MAC', # modifier
 ])
-def automatic_dependencies(*expressions: str) -> List[str]:
+def automatic_dependencies(*expressions: str,
+                           prefix: Optional[str] = None) -> List[str]:
     """Infer dependencies of a test case by looking for PSA_xxx symbols.
 
     The arguments are strings which should be C expressions. Do not use
     string literals or comments as this function is not smart enough to
     skip them.
+
+    `prefix`: prefix to use in dependencies. Defaults to ``'PSA_WANT_'``.
+              Use ``'MBEDTLS_PSA_BUILTIN_'`` when specifically testing
+              builtin implementations.
     """
     used = set()
     for expr in expressions:
         used.update(re.findall(r'PSA_(?:ALG|ECC_FAMILY|DH_FAMILY|KEY_TYPE)_\w+', expr))
     used.difference_update(SYMBOLS_WITHOUT_DEPENDENCY)
-    return sorted(psa_want_symbol(name) for name in used)
+    return sorted(psa_want_symbol(name, prefix=prefix) for name in used)
 
 # Define set of regular expressions and dependencies to optionally append
 # extra dependencies for test case based on key description.