Invalidate the tag_files.tfd after fclose(3)ing the stram associated

with it.  In main() assert that the tfd was actually invalidated.
This avoids closing an invalid fd.
From tb@; OK deraadt@ on an earlier version.

2 files changed, 6 insertions, 3 deletions

diff --git a/main.c b/main.c
index 5421a77c..e65d90a1 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.302 2017/08/21 15:42:58 schwarze Exp $ */
+/*	$Id: main.c,v 1.303 2018/02/23 16:47:10 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2012, 2014-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -1184,7 +1184,7 @@ spawn_pager(struct tag_files *tag_files)
 	if (dup2(tag_files->ofd, STDOUT_FILENO) == -1)
 		err((int)MANDOCLEVEL_SYSERR, "pager stdout");
 	close(tag_files->ofd);
-	close(tag_files->tfd);
+	assert(tag_files->tfd == -1);
 
 	/* Do not start the pager before controlling the terminal. */
 
diff --git a/tag.c b/tag.c
index 21ac6b32..c0832c4f 100644
--- a/tag.c
+++ b/tag.c
@@ -1,4 +1,4 @@
-/*	$Id: tag.c,v 1.18 2017/02/17 14:31:52 schwarze Exp $ */
+/*	$Id: tag.c,v 1.19 2018/02/23 16:47:10 schwarze Exp $ */
 /*
  * Copyright (c) 2015, 2016 Ingo Schwarze <schwarze@openbsd.org>
  *
@@ -213,6 +213,9 @@ tag_write(void)
 	ohash_delete(&tag_data);
 	if (stream != NULL)
 		fclose(stream);
+	else
+		close(tag_files.tfd);
+	tag_files.tfd = -1;
 }
 
 void