Stop rigctld and rotctld crashing when service threads cannot write to clients

Although there is  no reasonable recovery from SIGPIPE we  do not want
to terminate the server process,  just the client servicing thread. We
do this by setting the disposition for SIGPIPE to ignored, this causes
an EPIPE to be returned from blocked write() and send() calls that end
up trying to send to a broken pipe/socket.

configure.ac

@@ -234,7 +234,7 @@ AC_SUBST([NET_LIBS])
 
 dnl Checks for library functions.
 AC_CHECK_FUNCS([cfmakeraw floor getpagesize getpagesize gettimeofday inet_ntoa \
-ioctl memchr memmove memset pow rint select setitimer setlocale sigaction \
+ioctl memchr memmove memset pow rint select setitimer setlocale sigaction signal \
 snprintf socket sqrt strchr strdup strerror strncasecmp strrchr strstr strtol])
 AC_FUNC_ALLOCA
 

tests/rigctld.c

@@ -33,6 +33,7 @@
 #include <unistd.h>
 #include <ctype.h>
 #include <errno.h>
+#include <signal.h>
 
 #include <getopt.h>
 
@@ -172,6 +173,12 @@ int main(int argc, char *argv[])
 	char host[NI_MAXHOST];
 	char serv[NI_MAXSERV];
 
+#ifdef HAVE_PTHREAD
+	pthread_t thread;
+	pthread_attr_t attr;
+#endif
+	struct handle_data *arg;
+
 	while (1) {
 		int c;
 		int option_index = 0;
@@ -523,16 +530,29 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+#ifdef SIGPIPE
+  /* Ignore SIGPIPE as we will handle it at the write()/send() calls
+		 that will consequently fail with EPIPE. All child threads will
+		 inherit this disposition which is what we want. */
+#if HAVE_SIGACTION
+	struct sigaction act;
+	memset (&act, 0, sizeof act);
+	act.sa_handler = SIG_IGN;
+	act.sa_flags = SA_RESTART;
+	if (sigaction (SIGPIPE, &act, NULL)) {
+		handle_error (RIG_DEBUG_ERR, "sigaction");
+	}
+#elif HAVE_SIGNAL
+	if (SIG_ERR == signal (SIGPIPE, SIG_IGN)))
+		handle_error (RIG_DEBUG_ERR, "signal");
+	}
+#endif
+#endif
+
 	/*
 	 * main loop accepting connections
 	 */
 	do {
-#ifdef HAVE_PTHREAD
-		pthread_t thread;
-		pthread_attr_t attr;
-#endif
-		struct handle_data *arg;
-
 		arg = malloc(sizeof(struct handle_data));
 
 		if (!arg) {

tests/rotctld.c

@@ -34,6 +34,7 @@
 
 #include <getopt.h>
 #include <errno.h>
+#include <signal.h>
 
 #include <sys/types.h>          /* See NOTES */
 
@@ -160,6 +161,12 @@ int main(int argc, char *argv[])
 	char host[NI_MAXHOST];
 	char serv[NI_MAXSERV];
 
+#ifdef HAVE_PTHREAD
+	pthread_t thread;
+	pthread_attr_t attr;
+#endif
+	struct handle_data *arg;
+
 	while (1) {
 		int c;
 		int option_index = 0;
@@ -416,16 +423,29 @@ int main(int argc, char *argv[])
 		exit(1);
 	}
 
+#ifdef SIGPIPE
+  /* Ignore SIGPIPE as we will handle it at the write()/send() calls
+		 that will consequently fail with EPIPE. All child threads will
+		 inherit this disposition which is what we want. */
+#if HAVE_SIGACTION
+	struct sigaction act;
+	memset (&act, 0, sizeof act);
+	act.sa_handler = SIG_IGN;
+	act.sa_flags = SA_RESTART;
+	if (sigaction (SIGPIPE, &act, NULL)) {
+		handle_error (RIG_DEBUG_ERR, "sigaction");
+	}
+#elif HAVE_SIGNAL
+	if (SIG_ERR == signal (SIGPIPE, SIG_IGN)))
+		handle_error (RIG_DEBUG_ERR, "signal");
+	}
+#endif
+#endif
+
 	/*
 	 * main loop accepting connections
 	 */
 	do {
-#ifdef HAVE_PTHREAD
-		pthread_t thread;
-		pthread_attr_t attr;
-#endif
-		struct handle_data *arg;
-
 		arg = malloc(sizeof(struct handle_data));
 
 		if (!arg) {