Improve mbedtls_test_err_add_check documentation
Improve and clarify error messages and comments when checking error codes.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index a26f1ee..9bfe085 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -280,9 +280,15 @@
#if defined(MBEDTLS_TEST_HOOKS)
/**
- * \brief Check that a pure high-level error code is being combined with a
- * pure low-level error code as otherwise the resultant error code
+ * \brief Check that only a pure high-level error code is being combined with
+ * a pure low-level error code as otherwise the resultant error code
* would be corrupted.
+ *
+ * \note Both high-level and low-level error codes cannot be greater than
+ * zero however can be zero. If one error code is zero then the
+ * other error code is returned even if both codes are zero.
+ *
+ * \note If the check fails, fail the test currently being run.
*/
void mbedtls_test_err_add_check( int high, int low,
const char *file, int line);
diff --git a/tests/src/helpers.c b/tests/src/helpers.c
index 8319e90..8819674 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -287,27 +287,41 @@
void mbedtls_test_err_add_check( int high, int low,
const char *file, int line )
{
- if ( high > -0x1000 )
+ /* Error codes are always negative (a value of zero is a success) however
+ * their positive opposites can be easier to understand. The following
+ * examples given in comments have been made positive for ease of
+ * understanding. The structure of an error code is such:
+ *
+ * shhhhhhhllllllll
+ *
+ * s = sign bit.
+ * h = high level error code (includes high and module error codes).
+ * l = low level error code.
+ */
+ if ( high > -0x1000 ) // high < 0001000000000000
{
mbedtls_test_fail( "'high' is not a high-level error code",
line, file );
}
- else if ( high < -0x7F80 )
+ else if ( high < -0x7F80 ) // high > 0111111110000000
{
- mbedtls_test_fail( "'high' is greater than 16-bits", line, file );
+ mbedtls_test_fail( "'high' error code is greater than 15 bits",
+ line, file );
}
- else if ( ( high & 0x7F ) != 0 )
+ else if ( ( high & 0x7F ) != 0 ) // high & 0000000011111111
{
mbedtls_test_fail( "'high' contains a low-level error code",
line, file );
}
- else if ( low < -0x007F )
+ else if ( low < -0x007F ) // low > 0000000001111111
{
- mbedtls_test_fail( "'low' is greater than 8-bits", line, file );
+ mbedtls_test_fail( "'low' error code is greater than 7 bits",
+ line, file );
}
else if ( low > 0 )
{
- mbedtls_test_fail( "'low' is zero or greater", line, file );
+ mbedtls_test_fail( "'low' error code is greater than zero",
+ line, file );
}
}
#endif /* MBEDTLS_TEST_HOOKS */