From b58d97e33912a946005fd53e87508de9ebec9ad0 Mon Sep 17 00:00:00 2001
From: Mark Lumsden <lum@cvs.openbsd.org>
Date: Fri, 14 Jun 2019 14:27:43 +0000
Subject: Note a segv with fprintf if a file with long lines is loaded with
 debug code running.

---
 usr.bin/mg/log.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

(limited to 'usr.bin/mg/log.c')

diff --git a/usr.bin/mg/log.c b/usr.bin/mg/log.c
index dd9a6568a52..f69b9aae543 100644
--- a/usr.bin/mg/log.c
+++ b/usr.bin/mg/log.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: log.c,v 1.5 2019/06/12 18:21:07 lum Exp $	*/
+/*	$OpenBSD: log.c,v 1.6 2019/06/14 14:27:42 lum Exp $	*/
 
 /* 
  * This file is in the public domain.
@@ -21,6 +21,20 @@
  * written in the spirit of debugging (quickly and perhaps not ideal,
  * but it does what is required well enough). Should debugging become
  * more formalised within mg, then I would expect that to change.
+ *
+ * If you open a file with long lines to run through this debugging 
+ * code, you may run into problems with the 1st fprintf statement in
+ * in the mglog_lines() function. mg sometimes segvs at a strlen call
+ * in fprintf - possibly something to do with the format string?
+ * 	"%s%p b^%p f.%p %d %d\t%c|%s\n"
+ * When I get time I will look into it. But since my debugging 
+ * generally revolves around a file like:
+ * 
+ * abc
+ * def
+ * ghk
+ *
+ * I don't experience this bug. Just note it for future investigation.
  */
 
 #include <sys/queue.h>
@@ -156,6 +170,7 @@ mglog_lines(PF funct)
 		else
 			tmp = lp->l_text;
 
+		/* segv on fprintf below with long lines */
 		if (fprintf(fd, "%s%p b^%p f.%p %d %d\t%c|%s\n", curline,
 		    lp, lp->l_bp, lp->l_fp,
 		    lp->l_size, lp->l_used, o, tmp) == -1) {
-- 
cgit v1.2.3