psa: Add backwards compatible error codes

Add deprecated error codes to help transition between the previous
version of the PSA Crypto specification and the current one.

Author: Patater

include/psa/crypto_extra.h

@@ -37,6 +37,29 @@ extern "C" {
 /* UID for secure storage seed */
 #define PSA_CRYPTO_ITS_RANDOM_SEED_UID 0xFFFFFF52
 
+/*
+ * Deprecated PSA Crypto error code definitions
+ */
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#define PSA_ERROR_UNKNOWN_ERROR \
+    MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( PSA_ERROR_GENERIC_ERROR )
+#endif
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#define PSA_ERROR_OCCUPIED_SLOT \
+    MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( PSA_ERROR_ALREADY_EXISTS )
+#endif
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#define PSA_ERROR_EMPTY_SLOT \
+    MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( PSA_ERROR_DOES_NOT_EXIST )
+#endif
+
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#define PSA_ERROR_INSUFFICIENT_CAPACITY \
+    MBEDTLS_DEPRECATED_NUMERIC_CONSTANT( PSA_ERROR_INSUFFICIENT_DATA )
+#endif
+
 /**
  * \brief Library deinitialization.
  *

scripts/generate_psa_constants.py

@@ -167,6 +167,16 @@ def read_line(self, line):
             return
         elif (name.startswith('PSA_ERROR_') or name == 'PSA_SUCCESS') \
            and not parameter:
+            if name in [
+                        'PSA_ERROR_UNKNOWN_ERROR',
+                        'PSA_ERROR_OCCUPIED_SLOT',
+                        'PSA_ERROR_EMPTY_SLOT',
+                        'PSA_ERROR_INSUFFICIENT_CAPACITY'
+                        ]:
+                # Ad hoc skipping of deprecated error codes, which share
+                # numerical values with non-deprecated error codes
+                return
+
             self.statuses.add(name)
         elif name.startswith('PSA_KEY_TYPE_') and not parameter:
             self.key_types.add(name)