Timeout the server socket connection

Wait no more than 2 seconds for accepting the connection from the
device, since it blocks the event loop, preventing to react to SIGTERM
(Ctrl+C).

app/src/netutil.c

@@ -4,7 +4,7 @@
 
 // contrary to SDLNet_TCP_Send and SDLNet_TCP_Recv, SDLNet_TCP_Accept is non-blocking
 // so we need to block before calling it
-TCPsocket server_socket_accept(TCPsocket server_socket) {
+TCPsocket server_socket_accept(TCPsocket server_socket, Uint32 timeout_ms) {
     SDLNet_SocketSet set = SDLNet_AllocSocketSet(1);
     if (!set) {
         SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Could not allocate socket set");
@@ -17,9 +17,8 @@ TCPsocket server_socket_accept(TCPsocket server_socket) {
         return NULL;
     }
 
-    // timeout is (2^32-1) milliseconds, this should be sufficient
-    if (SDLNet_CheckSockets(set, -1) != 1) {
-        SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "Could not check socket");
+    if (SDLNet_CheckSockets(set, timeout_ms) != 1) {
+        SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "No connection to accept");
         SDLNet_FreeSocketSet(set);
         return NULL;
     }

app/src/netutil.h

@@ -4,6 +4,6 @@
 #include <SDL2/SDL_net.h>
 
 // blocking accept on the server socket
-TCPsocket server_socket_accept(TCPsocket server_socket);
+TCPsocket server_socket_accept(TCPsocket server_socket, Uint32 timeout_ms);
 
 #endif

app/src/scrcpy.c

@@ -111,10 +111,11 @@ SDL_bool scrcpy(const char *serial, Uint16 local_port, Uint16 max_size, Uint32 b
         goto finally_destroy_server;
     }
 
-    // to reduce startup time, we could be tempted to init other stuff before blocking here
-    // but we should not block after SDL_Init since it handles the signals (Ctrl+C) in its
-    // event loop: blocking could lead to deadlock
-    TCPsocket device_socket = server_connect_to(&server, serial);
+    // SDL initialization replace the signal handler for SIGTERM, so Ctrl+C is
+    // managed by the event loop. This blocking call blocks the event loop, so
+    // timeout the connection not to block indefinitely in case of SIGTERM.
+#define SERVER_CONNECT_TIMEOUT_MS 2000
+    TCPsocket device_socket = server_connect_to(&server, serial, SERVER_CONNECT_TIMEOUT_MS);
     if (!device_socket) {
         server_stop(&server, serial);
         ret = SDL_FALSE;

app/src/server.c

@@ -98,9 +98,9 @@ SDL_bool server_start(struct server *server, const char *serial, Uint16 local_po
     return SDL_TRUE;
 }
 
-TCPsocket server_connect_to(struct server *server, const char *serial) {
+TCPsocket server_connect_to(struct server *server, const char *serial, Uint32 timeout_ms) {
     SDL_assert(server->server_socket);
-    server->device_socket = server_socket_accept(server->server_socket);
+    server->device_socket = server_socket_accept(server->server_socket, timeout_ms);
 
     // we don't need the server socket anymore
     SDLNet_TCP_Close(server->server_socket);

app/src/server.h

@@ -26,7 +26,7 @@ SDL_bool server_start(struct server *server, const char *serial, Uint16 local_po
                       Uint16 max_size, Uint32 bit_rate);
 
 // block until the communication with the server is established
-TCPsocket server_connect_to(struct server *server, const char *serial);
+TCPsocket server_connect_to(struct server *server, const char *serial, Uint32 timeout_ms);
 
 // disconnect and kill the server process
 void server_stop(struct server *server, const char *serial);