From def515a241c013d38e1adc98dd83acce4303cb13 Mon Sep 17 00:00:00 2001
From: Jian Wan <jwan@arbor.net>
Date: Thu, 17 Jan 2019 15:19:53 +1100
Subject: [PATCH] fix segfault when pipe

---
 configure             | 4 ++--
 configure.in          | 4 ++--
 contrib/ipv6calc.spec | 2 +-
 ipv6calc/ipv6calc.c   | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/configure b/configure
index 434c2897..85a820ae 100755
--- a/configure
+++ b/configure
@@ -3076,7 +3076,7 @@ if ${ac_cv_prog_cc_g+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_save_c_werror_flag=$ac_c_werror_flag
-   ac_c_werror_flag=yes
+   ac_c_werror_flag=no
    ac_cv_prog_cc_g=no
    CFLAGS="-g"
    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -4196,7 +4196,7 @@ if ac_fn_c_try_compile "$LINENO"; then :
 
 				{ $as_echo "$as_me:${as_lineno-$LINENO}: result: *** CFLAGS supported: -Werror=format-security" >&5
 $as_echo "*** CFLAGS supported: -Werror=format-security" >&6; }
-				CFLAGS_EXTRA="-Wformat -Werror -Werror=format-security"
+				CFLAGS_EXTRA="-Wformat -Werror=format-security"
 
 else
 
diff --git a/configure.in b/configure.in
index 9534dd3d..8a78efd5 100644
--- a/configure.in
+++ b/configure.in
@@ -77,13 +77,13 @@ AC_ARG_ENABLE([compiler-warning-to-error],
 	],[
 		AC_MSG_RESULT([*** check for CFLAGS: -Werror=format-security])
 		CFLAGS_SAVE="$CFLAGS"
-		CFLAGS="$CFLAGS -Wformat -Werror -Werror=format-security"
+		CFLAGS="$CFLAGS -Wformat -Werror=format-security"
 		AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
 			     [[int a=1;]])
 			],
 			[
 				AC_MSG_RESULT([*** CFLAGS supported: -Werror=format-security])
-				CFLAGS_EXTRA="-Wformat -Werror -Werror=format-security"
+				CFLAGS_EXTRA="-Wformat -Werror=format-security"
 			],
 			[
 				AC_MSG_WARN([*** missing CFLAGS support: -Werror=format-security])
diff --git a/contrib/ipv6calc.spec b/contrib/ipv6calc.spec
index 87115636..f613b8ea 100644
--- a/contrib/ipv6calc.spec
+++ b/contrib/ipv6calc.spec
@@ -1,7 +1,7 @@
 # Project    : ipv6calc
 # File       : contrib/ipv6calc.spec
 # Copyright  : 2001-2018 by Peter Bieringer <pb@bieringer.de>
-# $Id: 0df17afba6c435c28b3c3d0323e0739d2f88678e $
+# $Id: 14c55e02c404183d20337376ae3a55f42ffaab0e $
 
 # enable the following for intermediate builds
 #%#define gitcommit d3a4108cb7aeb6f731bb07989f91d8a7f449f0f0
diff --git a/ipv6calc/ipv6calc.c b/ipv6calc/ipv6calc.c
index 796caff5..64d80560 100644
--- a/ipv6calc/ipv6calc.c
+++ b/ipv6calc/ipv6calc.c
@@ -884,7 +884,7 @@ int main(int argc, char *argv[]) {
 		DEBUGPRINT_WA(DEBUG_ipv6calc_general, "Token 1: '%s'", input1);
 
 		/* check for second token */
-		if (*ptrptr[0] != '\0') {
+		if (ptrptr && ptrptr[0] &&  *ptrptr[0] != '\0') {
 			input2 = *ptrptr;
 			inputc = 2;