Merge changes Id80bfca1,I8254c3f4 into main

* changes:
  clatd: one less shutdown log line
  clatd: rework sigterm & error handling
diff --git a/clatd/clatd.c b/clatd/clatd.c
index 9ac1663..9b1d987 100644
--- a/clatd/clatd.c
+++ b/clatd/clatd.c
@@ -49,7 +49,8 @@
 
 struct clat_config Global_Clatd_Config;
 
-volatile sig_atomic_t running = 1;
+volatile sig_atomic_t sigterm = 0;
+bool running = true;
 
 // reads IPv6 packet from AF_PACKET socket, translates to IPv4, writes to tun
 void process_packet_6_to_4(struct tun_data *tunnel) {
@@ -78,10 +79,11 @@
     if (errno != EAGAIN) {
       logmsg(ANDROID_LOG_WARN, "%s: read error: %s", __func__, strerror(errno));
     }
+    if (errno == ENETDOWN) running = false;
     return;
   } else if (readlen == 0) {
     logmsg(ANDROID_LOG_WARN, "%s: packet socket removed?", __func__);
-    running = 0;
+    running = false;
     return;
   } else if (readlen >= sizeof(buf)) {
     logmsg(ANDROID_LOG_WARN, "%s: read truncation - ignoring pkt", __func__);
@@ -161,10 +163,11 @@
     if (errno != EAGAIN) {
       logmsg(ANDROID_LOG_WARN, "%s: read error: %s", __func__, strerror(errno));
     }
+    if (errno == ENETDOWN) running = false;  // not sure if this can happen
     return;
   } else if (readlen == 0) {
     logmsg(ANDROID_LOG_WARN, "%s: tun interface removed", __func__);
-    running = 0;
+    running = false;
     return;
   } else if (readlen >= sizeof(buf)) {
     logmsg(ANDROID_LOG_WARN, "%s: read truncation - ignoring pkt", __func__);
@@ -278,7 +281,7 @@
     { tunnel->fd4, POLLIN, 0 },
   };
 
-  while (running) {
+  while (running && !sigterm) {
     if (poll(wait_fd, ARRAY_SIZE(wait_fd), -1) == -1) {
       if (errno != EINTR) {
         logmsg(ANDROID_LOG_WARN, "event_loop/poll returned an error: %s", strerror(errno));
diff --git a/clatd/clatd.h b/clatd/clatd.h
index 5b2b2e6..daa5ebc 100644
--- a/clatd/clatd.h
+++ b/clatd/clatd.h
@@ -52,7 +52,7 @@
 
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
-extern volatile sig_atomic_t running;
+extern volatile sig_atomic_t sigterm;
 
 void send_dad(int fd, const struct in6_addr* tgt);
 
diff --git a/clatd/main.c b/clatd/main.c
index 11067de..fca996b 100644
--- a/clatd/main.c
+++ b/clatd/main.c
@@ -34,10 +34,10 @@
 
 #define DEVICEPREFIX "v4-"
 
-/* function: stop_loop
+/* function: handle_sigterm
  * signal handler: stop the event loop
  */
-static void stop_loop(__attribute__((unused)) int unused) { running = 0; };
+static void handle_sigterm(__attribute__((unused)) int unused) { sigterm = 1; };
 
 /* function: print_help
  * in case the user is running this on the command line
@@ -183,7 +183,7 @@
   }
 
   // Loop until someone sends us a signal or brings down the tun interface.
-  if (signal(SIGTERM, stop_loop) == SIG_ERR) {
+  if (signal(SIGTERM, handle_sigterm) == SIG_ERR) {
     logmsg(ANDROID_LOG_FATAL, "sigterm handler failed: %s", strerror(errno));
     exit(1);
   }
@@ -201,18 +201,17 @@
 
   event_loop(&tunnel);
 
-  logmsg(ANDROID_LOG_INFO, "Shutting down clat on %s", uplink_interface);
-
-  if (running) {
-    logmsg(ANDROID_LOG_INFO, "Clatd on %s waiting for SIGTERM", uplink_interface);
+  if (sigterm) {
+    logmsg(ANDROID_LOG_INFO, "Shutting down clatd on %s, already received SIGTERM", uplink_interface);
+  } else {
+    // this implies running == false, ie. we received EOF or ENETDOWN error.
+    logmsg(ANDROID_LOG_INFO, "Shutting down clatd on %s, waiting for SIGTERM", uplink_interface);
     // let's give higher level java code 15 seconds to kill us,
     // but eventually terminate anyway, in case system server forgets about us...
-    // sleep() should be interrupted by SIGTERM, the handler should clear running
+    // sleep() should be interrupted by SIGTERM, the handler should set 'sigterm'
     sleep(15);
     logmsg(ANDROID_LOG_INFO, "Clatd on %s %s SIGTERM", uplink_interface,
-           running ? "timed out waiting for" : "received");
-  } else {
-    logmsg(ANDROID_LOG_INFO, "Clatd on %s already received SIGTERM", uplink_interface);
+           sigterm ? "received" : "timed out waiting for");
   }
   return 0;
 }