adns_str* etc.: Permit calling on adns_s_* values (not _max_)

This is useful because otherwise an application may not use these
values for its own errors, if that might result in them being passed
to the adns_strerror etc.

No code change: the table already has all the values.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/adns.h b/src/adns.h
index b8072ee..ba44b06 100644
--- a/src/adns.h
+++ b/src/adns.h
@@ -1089,7 +1089,9 @@ const char *adns_errtypeabbrev(adns_status st);
  *
  * If you call these functions with status values not actually
  * returned from other functions in the same adns library, the
- * returned information may be NULL.
+ * returned information may be NULL.  (You are also guaranteed
+ * that the return value will not be NULL for values in the
+ * adns_status enum, *except* for adns_s_max_XXXX.)
  */
 
 #ifdef __cplusplus