Show values when TEST_EQUAL fails

When TEST_EQUAL fails, show the two numerical values in the test log (only
with host_test). The values are printed in hexa and signed decimal.

The arguments of TEST_EQUAL must now be integers, not pointers or floats.
The current implementation requires them to fit in unsigned long long
Signed values no larger than long long will work too. The implementation
uses unsigned long long rather than uintmax_t to reduce portability
concerns. The snprintf function must support "%llx" and "%lld".

For this purpose, add room for two lines of text to the mbedtls_test_info
structure. This adds 154 bytes of global data.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/include/test/helpers.h

@@ -72,6 +72,8 @@ typedef struct
     const char *filename;
     int line_no;
     unsigned long step;
+    char line1[76];
+    char line2[76];
 #if defined(MBEDTLS_TEST_MUTEX_USAGE)
     const char *mutex_usage_error;
 #endif
@@ -130,6 +132,27 @@ void mbedtls_test_set_step( unsigned long step );
  */
 void mbedtls_test_info_reset( void );
 
+/**
+ * \brief           Record the current test case as a failure if two integers
+ *                  have a different value.
+ *
+ *                  This function is usually called via the macro
+ *                  #TEST_EQUAL.
+ *
+ * \param test      Description of the failure or assertion that failed. This
+ *                  MUST be a string literal. This normally has the form
+ *                  "EXPR1 == EXPR2" where EXPR1 has the value \p value1
+ *                  and EXPR2 has the value \p value2.
+ * \param line_no   Line number where the failure originated.
+ * \param filename  Filename where the failure originated.
+ * \param value1    The first value to compare.
+ * \param value2    The second value to compare.
+ *
+ * \return          \c 1 if the values are equal, otherwise \c 0.
+ */
+int mbedtls_test_equal( const char *test, int line_no, const char* filename,
+                        unsigned long long value1, unsigned long long value2 );
+
 /**
  * \brief          This function decodes the hexadecimal representation of
  *                 data.

tests/include/test/macros.h

@@ -84,15 +84,21 @@
        }                                                    \
     } while( 0 )
 
-/** Evaluate two expressions and fail the test case if they have different
+/** Evaluate two integer expressions and fail the test case if they have
- * values.
+ * different values.
  *
- * \param expr1     An expression to evaluate.
+ * The two expressions should have the same signedness, otherwise the
- * \param expr2     The expected value of \p expr1. This can be any
+ * comparison is not meaningful if the signed value is negative.
- *                  expression, but it is typically a constant.
+ *
+ * \param expr1     An integral-typed expression to evaluate.
+ * \param expr2     Another integral-typed expression to evaluate.
  */
-#define TEST_EQUAL( expr1, expr2 )              \
+#define TEST_EQUAL( expr1, expr2 )                                      \
-    TEST_ASSERT( ( expr1 ) == ( expr2 ) )
+    do {                                                                \
+        if( ! mbedtls_test_equal( #expr1 " == " #expr2, __LINE__, __FILE__, \
+                                  expr1, expr2 ) )                      \
+            goto exit;                                                  \
+    } while( 0 )
 
 /** Allocate memory dynamically and fail the test case if this fails.
  * The allocated memory will be filled with zeros.

tests/src/helpers.c

@@ -113,6 +113,31 @@ void mbedtls_test_info_reset( void )
     mbedtls_test_info.test = 0;
     mbedtls_test_info.line_no = 0;
     mbedtls_test_info.filename = 0;
+    memset( mbedtls_test_info.line1, 0, sizeof( mbedtls_test_info.line1 ) );
+    memset( mbedtls_test_info.line2, 0, sizeof( mbedtls_test_info.line2 ) );
+}
+
+int mbedtls_test_equal( const char *test, int line_no, const char* filename,
+                        unsigned long long value1, unsigned long long value2 )
+{
+    if( value1 == value2 )
+        return( 1 );
+    if( mbedtls_test_info.result == MBEDTLS_TEST_RESULT_FAILED )
+    {
+        /* We've already recorded the test as having failed. Don't
+         * overwrite any previous information about the failure. */
+        return( 0 );
+    }
+    mbedtls_test_fail( test, line_no, filename );
+    (void) mbedtls_snprintf( mbedtls_test_info.line1,
+                             sizeof( mbedtls_test_info.line1 ),
+                             "lhs = 0x%016llx = %lld",
+                             value1, (long long) value1 );
+    (void) mbedtls_snprintf( mbedtls_test_info.line2,
+                             sizeof( mbedtls_test_info.line2 ),
+                             "rhs = 0x%016llx = %lld",
+                             value2, (long long) value2 );
+    return( 0 );
 }
 
 int mbedtls_test_unhexify( unsigned char *obuf,

tests/src/psa_exercise_key.c

@@ -663,7 +663,7 @@ int mbedtls_test_psa_exported_key_sanity_check(
         TEST_EQUAL( mbedtls_asn1_get_tag( &p, end, &len,
                                           MBEDTLS_ASN1_SEQUENCE |
                                           MBEDTLS_ASN1_CONSTRUCTED ), 0 );
-        TEST_EQUAL( p + len, end );
+        TEST_EQUAL( len, end - p );
         if( ! mbedtls_test_asn1_skip_integer( &p, end, 0, 0, 0 ) )
             goto exit;
         if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
@@ -684,7 +684,7 @@ int mbedtls_test_psa_exported_key_sanity_check(
             goto exit;
         if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
             goto exit;
-        TEST_EQUAL( p, end );
+        TEST_EQUAL( p - end, 0 );
 
         TEST_ASSERT( exported_length <= PSA_EXPORT_KEY_PAIR_MAX_SIZE );
     }
@@ -716,12 +716,12 @@ int mbedtls_test_psa_exported_key_sanity_check(
                                           MBEDTLS_ASN1_SEQUENCE |
                                           MBEDTLS_ASN1_CONSTRUCTED ),
                     0 );
-        TEST_EQUAL( p + len, end );
+        TEST_EQUAL( len, end - p );
         if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
             goto exit;
         if( ! mbedtls_test_asn1_skip_integer( &p, end, 2, bits, 1 ) )
             goto exit;
-        TEST_EQUAL( p, end );
+        TEST_EQUAL( p - end, 0 );
 
 
         TEST_ASSERT( exported_length <=

tests/suites/host_test.function

@@ -778,6 +778,12 @@ int execute_tests( int argc , const char ** argv )
                     mbedtls_fprintf( stdout, "line %d, %s",
                                      mbedtls_test_info.line_no,
                                      mbedtls_test_info.filename );
+                    if( mbedtls_test_info.line1[0] != 0 )
+                        mbedtls_fprintf( stdout, "\n  %s",
+                                         mbedtls_test_info.line1 );
+                    if( mbedtls_test_info.line2[0] != 0 )
+                        mbedtls_fprintf( stdout, "\n  %s",
+                                         mbedtls_test_info.line2 );
                 }
                 fflush( stdout );
             }