From 69f72770761d824373a4f33f55beb9e467966ef1 Mon Sep 17 00:00:00 2001
From: David van Leusen <jvleusen@gmail.com>
Date: Mon, 27 Jul 2020 15:39:53 +0200
Subject: [PATCH 1/2] implement finish handler through flag instead of direct
 call in signal handler

---
 src/fping.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/fping.c b/src/fping.c
index 565ac01..327266a 100644
--- a/src/fping.c
+++ b/src/fping.c
@@ -304,6 +304,7 @@ int hints_ai_family = AF_UNSPEC;
 #endif
 
 volatile sig_atomic_t status_snapshot = 0;
+volatile sig_atomic_t finish_requested = 0;
 
 unsigned int debugging = 0;
 
@@ -383,7 +384,7 @@ void print_per_system_splits(void);
 void print_netdata(void);
 void print_global_stats(void);
 void main_loop();
-void sigstatus();
+void signal_handler(int);
 void finish();
 const char* sprint_tm(int64_t t);
 void ev_enqueue(struct event_queue *queue, struct event *event);
@@ -1110,8 +1111,8 @@ int main(int argc, char** argv)
     init_ping_buffer_ipv6(ping_data_size);
 #endif
 
-    signal(SIGINT, finish);
-    signal(SIGQUIT, sigstatus);
+    signal(SIGINT, signal_handler);
+    signal(SIGQUIT, signal_handler);
     setlinebuf(stdout);
 
     if (report_interval) {
@@ -1375,6 +1376,11 @@ void main_loop()
             break;
         }
 
+        /* end of loop was requested by interrupt signal handler */
+        if (finish_requested) {
+            break;
+        }
+
         /* Receive replies */
         /* (this is what sleeps during each loop iteration) */
         dbg_printf("waiting up to %ld ms\n", wait_time/100);
@@ -1405,21 +1411,30 @@ void main_loop()
 
 /************************************************************
 
-  Function: sigstatus
+  Function: signal_handler
 
 *************************************************************
 
-  Inputs:  void (none)
+  Inputs:  int signum
 
   Description:
 
   SIGQUIT signal handler - set flag and return
+  SIGINT signal handler - set flag and return
 
 ************************************************************/
 
-void sigstatus()
+void signal_handler(int signum)
 {
-    status_snapshot = 1;
+    switch (signum) {
+    case SIGINT:
+        finish_requested = 1;
+        break;
+
+    case SIGQUIT:
+        status_snapshot = 1;
+        break;
+    }
 }
 
 

From 254573f241142ea72cc9322e84724be16cc85afa Mon Sep 17 00:00:00 2001
From: David van Leusen <jvleusen@gmail.com>
Date: Mon, 27 Jul 2020 15:48:20 +0200
Subject: [PATCH 2/2] use sigaction when possible

---
 configure.ac |  4 ++++
 src/fping.c  | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/configure.ac b/configure.ac
index 764e958..c7df87a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -73,6 +73,10 @@ AC_CHECK_FUNC(connect)
 if test $ac_cv_func_connect = no; then
     AC_CHECK_LIB(socket, connect)
 fi
+AC_CHECK_FUNC(sigaction)
+if test $ac_cv_func_sigaction = yes; then
+    AC_DEFINE([USE_SIGACTION],[1],[Define if sigaction is available.])
+fi
 
 AH_TOP([
 #ifndef CONFIG_H
diff --git a/src/fping.c b/src/fping.c
index 327266a..1efd4f8 100644
--- a/src/fping.c
+++ b/src/fping.c
@@ -434,6 +434,9 @@ int main(int argc, char** argv)
     uid_t uid;
     int tos = 0;
     struct optparse optparse_state;
+#ifdef USE_SIGACTION
+    struct sigaction act;
+#endif
 
     /* pre-parse -h/--help, so that we also can output help information
      * without trying to open the socket, which might fail */
@@ -1111,8 +1114,20 @@ int main(int argc, char** argv)
     init_ping_buffer_ipv6(ping_data_size);
 #endif
 
+#ifdef USE_SIGACTION
+    memset(&act, 0, sizeof(act));
+    act.sa_handler = signal_handler;
+    sigemptyset(&act.sa_mask);
+    sigaddset(&act.sa_mask, SIGINT);
+    sigaddset(&act.sa_mask, SIGQUIT);
+    act.sa_flags = SA_RESTART;
+    if (sigaction(SIGQUIT, &act, NULL) || sigaction(SIGINT, &act, NULL)) {
+        crash_and_burn("failure to set signal handler");
+    }
+#else
     signal(SIGINT, signal_handler);
     signal(SIGQUIT, signal_handler);
+#endif
     setlinebuf(stdout);
 
     if (report_interval) {