Move MBEDTLS_ERR_ADD macro and function to common.*

`error.c` is a file generated from `error.h` and thus cannot contain the code
that was previously added. This commit fixes that issue by moving the
`MBEDTLS_ERR_ADD` macro and associated function and function pointer into
`common.h` and `common.c`.

Also fix a typo in `tests/include/test/helpers.h` where tabs were accidentally
used instead of spaces.

Signed-off-by: Chris Jones <christopher.jones@arm.com>

include/mbedtls/error.h

@@ -114,16 +114,6 @@ extern "C" {
 #define MBEDTLS_ERR_ERROR_GENERIC_ERROR       -0x0001  /**< Generic error */
 #define MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED -0x006E  /**< This is a bug in the library */
 
-#if defined(MBEDTLS_TEST_HOOKS)
-void (*mbedtls_test_err_add_hook)( int, int, const char *, int );
-int mbedtls_err_add( int high, int low, const char *file, int line );
-#define MBEDTLS_ERR_ADD( high, low )  \
-    ( mbedtls_err_add( high, low, __FILE__, __LINE__ ) )
-#else
-#define MBEDTLS_ERR_ADD( high, low ) \
-    ( high + low )
-#endif
-
 /**
  * \brief Translate a mbed TLS error code into a string representation,
  *        Result is truncated if necessary and always includes a terminating

library/common.c

@@ -0,0 +1,27 @@
+/*
+ *  Internal invasive testing helper functions
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#if defined(MBEDTLS_TEST_HOOKS)
+void (*mbedtls_test_err_add_hook)( int, int, const char *, int );
+int mbedtls_err_add( int high, int low, const char *file, int line ) {
+    if( mbedtls_test_err_add_hook != NULL )
+        (*mbedtls_test_err_add_hook)( high, low, file, line );
+    return ( high + low );
+}
+#endif

library/common.h

@@ -29,6 +29,7 @@
 #include "mbedtls/config.h"
 #endif
 
+#if defined(MBEDTLS_TEST_HOOKS)
 /** Helper to define a function as static except when building invasive tests.
  *
  * If a function is only used inside its own source file and should be
@@ -44,10 +45,25 @@
  * #endif
  * ```
  */
-#if defined(MBEDTLS_TEST_HOOKS)
 #define MBEDTLS_STATIC_TESTABLE
+
+/** Helper macro and function to combine a high and low level error code.
+ * 
+ * This function uses a hook (`mbedtls_test_err_add_hook`) to allow invasive
+ * testing of its inputs. This is used in the test infrastructure to report
+ * on errors when combining two error codes of the same level (e.g: two high
+ * or two low level errors).
+ */
+int mbedtls_err_add( int high, int low, const char *file, int line );
+#define MBEDTLS_ERR_ADD( high, low )  \
+    ( mbedtls_err_add( high, low, __FILE__, __LINE__ ) )
+
 #else
 #define MBEDTLS_STATIC_TESTABLE static
-#endif
+
+#define MBEDTLS_ERR_ADD( high, low ) \
+    ( high + low )
+
+#endif /* MBEDTLS_TEST_HOOKS */
 
 #endif /* MBEDTLS_LIBRARY_COMMON_H */

library/error.c

@@ -210,13 +210,6 @@
 #include "mbedtls/xtea.h"
 #endif
 
-#if defined(MBEDTLS_TEST_HOOKS)
-int mbedtls_err_add( int high, int low, const char *file, int line ) {
-    if( mbedtls_test_err_add_hook != NULL )
-        (*mbedtls_test_err_add_hook)( high, low, file, line );
-    return ( high + low );
-}
-#endif
 
 const char * mbedtls_high_level_strerr( int error_code )
 {

tests/suites/main_test.function

@@ -33,10 +33,6 @@
 #include "psa/crypto.h"
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
-#if defined(MBEDTLS_TEST_HOOKS)
-#include "mbedtls/error.h"
-#endif
-
 /* Test code may use deprecated identifiers only if the preprocessor symbol
  * MBEDTLS_TEST_DEPRECATED is defined. When building tests, set
  * MBEDTLS_TEST_DEPRECATED explicitly if MBEDTLS_DEPRECATED_WARNING is

visualc/VS2010/mbedTLS.vcxproj

@@ -293,6 +293,7 @@
     <ClCompile Include="..\..\library\cipher.c" />
     <ClCompile Include="..\..\library\cipher_wrap.c" />
     <ClCompile Include="..\..\library\cmac.c" />
+    <ClCompile Include="..\..\library\common.c" />
     <ClCompile Include="..\..\library\ctr_drbg.c" />
     <ClCompile Include="..\..\library\debug.c" />
     <ClCompile Include="..\..\library\des.c" />