Add an error type for circular references

include/akerror.tmpl.h

@@ -37,6 +37,7 @@
 #define AKERR_BEHAVIOR              (AKERR_LAST_ERRNO_VALUE + 13)
 #define AKERR_RELATIONSHIP          (AKERR_LAST_ERRNO_VALUE + 14)
 #define AKERR_EOF                   (AKERR_LAST_ERRNO_VALUE + 15)
+#define AKERR_CIRCULAR_REFERENCE    (AKERR_LAST_ERRNO_VALUE + 16)
 
 #ifndef AKERR_MAX_ERR_VALUE
 #define AKERR_MAX_ERR_VALUE (AKERR_LAST_ERRNO_VALUE + 15)
@@ -185,7 +186,8 @@ void akerr_init_errno(void);
 
 #define VALID(__err_context, __stmt)                       \
     __stmt;                                                \
-    if ( akerr_valid_error_address(__err_context) == 1 ) { \
+    if ( akerr_valid_error_address(__err_context) == 0 ) { \
+	__err_context = NULL;                              \
 	FAIL(__err_context, AKERR_BEHAVIOR, "Received (akerr_Error *) from an invalid memory region. (Did the method finish without calling SUCCEED_RETURN?)"); \
     }
 

src/error.c

@@ -17,7 +17,11 @@ akerr_ErrorContext AKERR_ARRAY_ERROR[AKERR_MAX_ARRAY_ERROR];
 int akerr_valid_error_address(akerr_ErrorContext *ptr)
 {
     // Is this within the memory region occupied by AKERR_ARRAY_ERROR?
-    return ((ptr >= &AKERR_ARRAY_ERROR[0]) && (ptr <= &AKERR_ARRAY_ERROR[AKERR_MAX_ARRAY_ERROR-1]));
+    if ( ptr == NULL ) {
+	return 1;
+    }
+    return ((ptr >= &AKERR_ARRAY_ERROR[0]) &&
+	    (ptr <= &AKERR_ARRAY_ERROR[AKERR_MAX_ARRAY_ERROR-1]));
 }
 
 void akerr_default_logger(const char *fmt, ...)
@@ -65,6 +69,7 @@ void akerr_init()
 	akerr_name_for_status(AKERR_VALUE, "Value Error");
 	akerr_name_for_status(AKERR_BEHAVIOR, "Behavior Error");
 	akerr_name_for_status(AKERR_RELATIONSHIP, "Relationship Error");
+	akerr_name_for_status(AKERR_CIRCULAR_REFERENCE, "Circular Reference Error");
 #if (defined(AKERR_USE_STDLIB) && AKERR_USE_STDLIB == 1) || (!defined(AKERR_USE_STDLIB))
 	akerr_init_errno();
 #endif