block TERM and INT from all but the main thread. (Pretty much untested; doesn't fix hang-on-SIGINT.)

xwords4/relay/http.cpp

@@ -213,6 +213,8 @@ class HttpInstance {
 static void*
 http_thread_main( void* arg )
 {
+    blockSignals();
+
     HttpInstance* inst = (HttpInstance*)arg;
     HttpState* state = inst->m_state;
     int sock = inst->m_sock;

xwords4/relay/tpool.cpp

@@ -195,6 +195,8 @@ XWThreadPool::get_process_packet( int socket )
 /* static */ void*
 XWThreadPool::tpool_main( void* closure )
 {
+    blockSignals();
+
     XWThreadPool* me = (XWThreadPool*)closure;
     return me->real_tpool_main();
 }
@@ -377,6 +379,8 @@ XWThreadPool::real_listener()
 /* static */ void*
 XWThreadPool::listener_main( void* closure )
 {
+    blockSignals();    
+
     XWThreadPool* me = (XWThreadPool*)closure;
     return me->real_listener();
 }

xwords4/relay/xwrelay.cpp

@@ -437,6 +437,17 @@ uptime( void )
     return time(NULL) - startTime;
 }
 
+void
+blockSignals( void )
+{
+    sigset_t set;
+    sigemptyset( &set );
+    sigaddset( &set, SIGINT );
+    sigaddset( &set, SIGTERM);
+    int s = pthread_sigmask( SIG_BLOCK, &set, NULL );
+    assert( 0 == s );
+}
+
 int
 GetNSpawns(void)
 {
@@ -669,6 +680,7 @@ read_packet( int sock, unsigned char* buf, int buflen )
 static void*
 handle_proxy_tproc( void* closure )
 {
+    blockSignals();
     int sock = (int)closure;
 
     unsigned char buf[MAX_PROXY_MSGLEN];

xwords4/relay/xwrelay_priv.h

@@ -23,6 +23,8 @@ bool send_with_length_unsafe( int socket, unsigned char* buf, int bufLen );
 
 time_t uptime(void);
 
+void blockSignals( void );      /* call from all but main thread */
+
 int GetNSpawns(void);
 
 int make_socket( unsigned long addr, unsigned short port );