vtest: add experimental multi-client support

Add --multi-clients to enable experimental multi-client support.

Note that multi-client should be enabled only when the clients know
and trust each other.  This is because resources are global among
the clients.  Two clients trying to create two resources with the
same id will result in an id conflict for example.

Proper multi-client support requires changes to the protocol.  The
main change will be for the server to generate globally unique
resource ids and enforce access controls.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-By: Gert Wollny <gert.wollny@collabora.com>
Reviewed-By: Gurchetan Singh <gurchetansingh@chromium.org>

vtest/vtest_server.c

@@ -77,6 +77,7 @@ struct vtest_server
    bool main_server;
    bool do_fork;
    bool loop;
+   bool multi_clients;
 
    bool use_glx;
    bool use_egl_surfaceless;
@@ -100,6 +101,7 @@ struct vtest_server server = {
    .main_server = true,
    .do_fork = true,
    .loop = true,
+   .multi_clients = false,
 
    .ctx_flags = 0,
 };
@@ -146,6 +148,7 @@ while (__AFL_LOOP(1000)) {
 
 #define OPT_NO_FORK 'f'
 #define OPT_NO_LOOP_OR_FORK 'l'
+#define OPT_MULTI_CLIENTS 'm'
 #define OPT_USE_GLX 'x'
 #define OPT_USE_EGL_SURFACELESS 's'
 #define OPT_USE_GLES 'e'
@@ -158,6 +161,7 @@ static void vtest_server_parse_args(int argc, char **argv)
    static struct option long_options[] = {
       {"no-fork",             no_argument, NULL, OPT_NO_FORK},
       {"no-loop-or-fork",     no_argument, NULL, OPT_NO_LOOP_OR_FORK},
+      {"multi-clients",       no_argument, NULL, OPT_MULTI_CLIENTS},
       {"use-glx",             no_argument, NULL, OPT_USE_GLX},
       {"use-egl-surfaceless", no_argument, NULL, OPT_USE_EGL_SURFACELESS},
       {"use-gles",            no_argument, NULL, OPT_USE_GLES},
@@ -181,6 +185,10 @@ static void vtest_server_parse_args(int argc, char **argv)
          server.do_fork = false;
          server.loop = false;
          break;
+      case OPT_MULTI_CLIENTS:
+         printf("EXPERIMENTAL: clients must know and trust each other\n");
+         server.multi_clients = true;
+         break;
       case OPT_USE_GLX:
          server.use_glx = true;
          break;
@@ -194,8 +202,9 @@ static void vtest_server_parse_args(int argc, char **argv)
          server.render_device = optarg;
          break;
       default:
-         printf("Usage: %s [--no-fork] [--no-loop-or-fork] [--use-glx] "
+         printf("Usage: %s [--no-fork] [--no-loop-or-fork] [--multi-clients] "
-                "[--use-egl-surfaceless] [--use-gles] [--rendernode <dev>]"
+                "[--use-glx] [--use-egl-surfaceless] [--use-gles] "
+                "[--rendernode <dev>]"
                 " [file]\n", argv[0]);
          exit(EXIT_FAILURE);
          break;
@@ -207,6 +216,7 @@ static void vtest_server_parse_args(int argc, char **argv)
       server.read_file = argv[optind];
       server.loop = false;
       server.do_fork = false;
+      server.multi_clients = false;
    }
 
    server.ctx_flags = VIRGL_RENDERER_USE_EGL;
@@ -361,8 +371,8 @@ static void vtest_server_wait_clients(void)
       max_fd = MAX2(client->in_fd, max_fd);
    }
 
-   /* accept new clients when there is none */
+   /* accept new clients when there is none or when multi_clients is set */
-   if (server.socket >= 0 && max_fd < 0) {
+   if (server.socket >= 0 && (max_fd < 0 || server.multi_clients)) {
       FD_SET(server.socket, &read_fds);
       max_fd = MAX2(server.socket, max_fd);
    }
@@ -449,6 +459,7 @@ static pid_t vtest_server_fork(void)
       server.main_server = false;
       server.do_fork = false;
       server.loop = false;
+      server.multi_clients = false;
    }
 
    return pid;