The ctags(1) file format uses whitespace as a field delimiter, and

there is no escaping mechanism, so tags cannot contain whitespace.
Consequently, we used to simply not tag macro arguments containing
space characters.  Instead, let's tag the first word, unless there
is a proper match for that word somewhere else.  For example, this
makes ":tquery" work in ntpd.conf(5).

Feature suggested by kn@, who also thinks the implementation looks
reasonable and works in his testing.

1 files changed, 27 insertions, 10 deletions

diff --git a/usr.bin/mandoc/tag.c b/usr.bin/mandoc/tag.c
index 9c9674be9d7..e7d086e8606 100644
--- a/usr.bin/mandoc/tag.c
+++ b/usr.bin/mandoc/tag.c
@@ -1,6 +1,6 @@
-/*	$OpenBSD: tag.c,v 1.19 2018/02/08 01:36:38 tb Exp $ */
+/*	$OpenBSD: tag.c,v 1.20 2018/10/23 20:41:59 schwarze Exp $ */
 /*
- * Copyright (c) 2015, 2016 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2015, 2016, 2018 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -16,6 +16,7 @@
  */
 #include <sys/types.h>
 
+#include <limits.h>
 #include <signal.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -119,41 +120,57 @@ fail:
 
 /*
  * Set the line number where a term is defined,
- * unless it is already defined at a higher priority.
+ * unless it is already defined at a lower priority.
  */
 void
 tag_put(const char *s, int prio, size_t line)
 {
 	struct tag_entry	*entry;
+	const char		*se;
 	size_t			 len;
 	unsigned int		 slot;
 
-	/* Sanity checks. */
-
 	if (tag_files.tfd <= 0)
 		return;
+
 	if (s[0] == '\\' && (s[1] == '&' || s[1] == 'e'))
 		s += 2;
-	if (*s == '\0' || strchr(s, ' ') != NULL)
+
+	/*
+	 * Skip whitespace and whatever follows it,
+	 * and if there is any, downgrade the priority.
+	 */
+
+	len = strcspn(s, " \t");
+	if (len == 0)
 		return;
 
-	slot = ohash_qlookup(&tag_data, s);
+	se = s + len;
+	if (*se != '\0')
+		prio = INT_MAX;
+
+	slot = ohash_qlookupi(&tag_data, s, &se);
 	entry = ohash_find(&tag_data, slot);
 
 	if (entry == NULL) {
 
 		/* Build a new entry. */
 
-		len = strlen(s) + 1;
-		entry = mandoc_malloc(sizeof(*entry) + len);
+		entry = mandoc_malloc(sizeof(*entry) + len + 1);
 		memcpy(entry->s, s, len);
+		entry->s[len] = '\0';
 		entry->lines = NULL;
 		entry->maxlines = entry->nlines = 0;
 		ohash_insert(&tag_data, slot, entry);
 
 	} else {
 
-		/* Handle priority 0 entries. */
+		/*
+		 * Lower priority numbers take precedence,
+		 * but 0 is special.
+		 * A tag with priority 0 is only used
+		 * if the tag occurs exactly once.
+		 */
 
 		if (prio == 0) {
 			if (entry->prio == 0)