From 286b86d62c350a06f3486abd7a9e949b684e4e0c Mon Sep 17 00:00:00 2001
From: "Nicholas J. Kain" <nicholas@kain.us>
Date: Thu, 24 Feb 2022 05:06:12 -0500
Subject: [PATCH] Preserve errno across signals.

---
 ndhc.c    |  2 ++
 scriptd.c | 11 +++++------
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/ndhc.c b/ndhc.c
index e4851e8..27d488d 100644
--- a/ndhc.c
+++ b/ndhc.c
@@ -149,6 +149,7 @@ void show_usage(void)
 
 static void signal_handler(int signo)
 {
+    int serrno = errno;
     switch (signo) {
     case SIGCHLD: {
         static const char errstr[] = "ndhc-master: Subprocess terminated unexpectedly. Exiting.\n";
@@ -161,6 +162,7 @@ static void signal_handler(int signo)
     case SIGUSR2: l_signal_release = 1; break;
     default: break;
     }
+    errno = serrno;
 }
 
 void signal_exit(int status)
diff --git a/scriptd.c b/scriptd.c
index 6512322..148c588 100644
--- a/scriptd.c
+++ b/scriptd.c
@@ -123,14 +123,13 @@ static void do_scriptd_work(void)
 
 static void signal_handler(int signo)
 {
-    switch (signo) {
-    case SIGCHLD:
+    int serrno = errno;
+    if (signo == SIGCHLD) {
         while (waitpid(-1, NULL, WNOHANG) > 0);
-        break;
-    case SIGINT:
-    case SIGTERM: _exit(EXIT_FAILURE); break;
-    default: break;
+    } else if (signo == SIGINT || signo == SIGTERM) {
+        _exit(EXIT_FAILURE);
     }
+    errno = serrno;
 }
 
 static void setup_signals_scriptd(void)