===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/mandoc/mandocdb.c,v
retrieving revision 1.198
retrieving revision 1.199
diff -c -r1.198 -r1.199
*** src/usr.bin/mandoc/mandocdb.c	2017/05/05 15:16:25	1.198
--- src/usr.bin/mandoc/mandocdb.c	2017/05/17 22:26:52	1.199
***************
*** 1,4 ****
! /*	$OpenBSD: mandocdb.c,v 1.198 2017/05/05 15:16:25 schwarze Exp $ */
  /*
   * Copyright (c) 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
   * Copyright (c) 2011-2017 Ingo Schwarze <schwarze@openbsd.org>
--- 1,4 ----
! /*	$OpenBSD: mandocdb.c,v 1.199 2017/05/17 22:26:52 schwarze Exp $ */
  /*
   * Copyright (c) 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
   * Copyright (c) 2011-2017 Ingo Schwarze <schwarze@openbsd.org>
***************
*** 2082,2087 ****
--- 2082,2104 ----
  	int		 status;
  	pid_t		 child;
  
+ 	/*
+ 	 * Do not write empty databases, and delete existing ones
+ 	 * when makewhatis -u causes them to become empty.
+ 	 */
+ 
+ 	dba_array_start(dba->pages);
+ 	if (dba_array_next(dba->pages) == NULL) {
+ 		if (unlink(MANDOC_DB) == -1)
+ 			say(MANDOC_DB, "&unlink");
+ 		return;
+ 	}
+ 
+ 	/*
+ 	 * Build the database in a temporary file,
+ 	 * then atomically move it into place.
+ 	 */
+ 
  	if (dba_write(MANDOC_DB "~", dba) != -1) {
  		if (rename(MANDOC_DB "~", MANDOC_DB) == -1) {
  			exitcode = (int)MANDOCLEVEL_SYSERR;
***************
*** 2090,2095 ****
--- 2107,2117 ----
  		}
  		return;
  	}
+ 
+ 	/*
+ 	 * We lack write permission and cannot replace the database
+ 	 * file, but let's at least check whether the data changed.
+ 	 */
  
  	(void)strlcpy(tfn, "/tmp/mandocdb.XXXXXXXX", sizeof(tfn));
  	if (mkdtemp(tfn) == NULL) {