Abort endless loops during roff macro and string expansion.

For now, use the simplest conceivable approach, like groff does:
Just a fixed, ugly input stack limit.
"check it in" kristaps@

1 files changed, 1 insertions, 0 deletions

diff --git a/mandoc.h b/mandoc.h
index 041b004f..58c339fd 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -101,6 +101,7 @@ enum	mandocerr {
 
 	MANDOCERR_ERROR, /* ===== start of errors ===== */
 
+	MANDOCERR_ROFFLOOP, /* input stack limit exceeded, infinite loop? */
 	MANDOCERR_BADCHAR, /* skipping bad character */
 	MANDOCERR_NOTEXT, /* skipping text before the first section header */
 	MANDOCERR_MACRO, /* skipping unknown macro */