[src/trunk]: src/usr.bin/m4 Behave like gnu m4; when the error output file ca...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e34baaed6128
branches:  trunk
changeset: 997787:e34baaed6128
user:      christos <christos%NetBSD.org@localhost>
date:      Tue Mar 26 15:00:34 2019 +0000

description:
Behave like gnu m4; when the error output file cannot be opened, just warn
and keep going.

diffstat:

 usr.bin/m4/main.c |  18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)

diffs (47 lines):

diff -r 0bd42724ddba -r e34baaed6128 usr.bin/m4/main.c
--- a/usr.bin/m4/main.c Tue Mar 26 14:55:02 2019 +0000
+++ b/usr.bin/m4/main.c Tue Mar 26 15:00:34 2019 +0000
@@ -1,5 +1,5 @@
 /*     $OpenBSD: main.c,v 1.77 2009/10/14 17:19:47 sthen Exp $ */
-/*     $NetBSD: main.c,v 1.46 2016/01/23 14:24:43 christos Exp $       */
+/*     $NetBSD: main.c,v 1.47 2019/03/26 15:00:34 christos Exp $       */
 
 /*-
  * Copyright (c) 1989, 1993
@@ -42,7 +42,7 @@
 #include "nbtool_config.h"
 #endif
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: main.c,v 1.46 2016/01/23 14:24:43 christos Exp $");
+__RCSID("$NetBSD: main.c,v 1.47 2019/03/26 15:00:34 christos Exp $");
 #include <assert.h>
 #include <signal.h>
 #include <getopt.h>
@@ -228,6 +228,7 @@
        int c;
        int n;
        char *p;
+       FILE *sfp;
 
        setprogname(argv[0]);
 
@@ -263,9 +264,16 @@
                        fatal_warnings++;
                        break;
                case 'e':
-                       if (freopen(optarg, "w+", stderr) == NULL)
-                               err(EXIT_FAILURE, "Can't redirect errors to `%s'",
-                                   optarg);
+                       /*
+                        * Don't use freopen here because if it fails
+                        * we lose stderr, instead trash it.
+                        */
+                       if ((sfp = fopen(optarg, "w+")) == NULL) {
+                               warn("Can't redirect errors to `%s'", optarg);
+                               break;
+                       }
+                       fclose(stderr);
+                       memcpy(stderr, sfp, sizeof(*sfp));
                        break;
                case 'F':
                        freeze = optarg;