diff options
| -rw-r--r-- | include/wlr/xwayland.h | 5 | ||||
| -rw-r--r-- | xwayland/server.c | 63 |
2 files changed, 52 insertions, 16 deletions
diff --git a/include/wlr/xwayland.h b/include/wlr/xwayland.h index 5488971a..fd14ff25 100644 --- a/include/wlr/xwayland.h +++ b/include/wlr/xwayland.h @@ -22,7 +22,7 @@ struct wlr_xwayland_cursor; struct wlr_xwayland_server { pid_t pid; struct wl_client *client; - struct wl_event_source *sigusr1_source; + struct wl_event_source *pipe_source; int wm_fd[2], wl_fd[2]; time_t server_start; @@ -236,9 +236,6 @@ void wlr_xwayland_server_destroy(struct wlr_xwayland_server *server); * * The server supports a lazy mode in which Xwayland is only started when a * client tries to connect. - * - * Note: wlr_xwayland will setup a global SIGUSR1 handler on the compositor - * process. */ struct wlr_xwayland *wlr_xwayland_create(struct wl_display *wl_display, struct wlr_compositor *compositor, bool lazy); diff --git a/xwayland/server.c b/xwayland/server.c index e022f871..f72b668d 100644 --- a/xwayland/server.c +++ b/xwayland/server.c @@ -57,6 +57,7 @@ noreturn static void exec_xwayland(struct wlr_xwayland_server *server) { } /* Make Xwayland signal us when it's ready */ + /* TODO: can we use -displayfd instead? */ signal(SIGUSR1, SIG_IGN); char *argv[] = { @@ -139,8 +140,8 @@ static void server_finish_process(struct wlr_xwayland_server *server) { wl_list_remove(&server->client_destroy.link); wl_client_destroy(server->client); } - if (server->sigusr1_source) { - wl_event_source_remove(server->sigusr1_source); + if (server->pipe_source) { + wl_event_source_remove(server->pipe_source); } safe_close(server->wl_fd[0]); @@ -184,8 +185,8 @@ static void handle_client_destroy(struct wl_listener *listener, void *data) { struct wlr_xwayland_server *server = wl_container_of(listener, server, client_destroy); - if (server->sigusr1_source) { - // Xwayland failed to start, let the sigusr1 handler deal with it + if (server->pipe_source) { + // Xwayland failed to start, let the readiness handler deal with it return; } @@ -219,7 +220,21 @@ static void handle_display_destroy(struct wl_listener *listener, void *data) { wlr_xwayland_server_destroy(server); } -static int xserver_handle_ready(int signal_number, void *data) { +static int xserver_handle_ready(int fd, uint32_t mask, void *data) { + // There are three ways in which we can end up here, from server_start: + // 1. the second fork failed + // 2. the exec failed + // 3. Xwayland sent a SIGUSR1 + // + // All three cases result in a write to the pipe, which triggers us. + // + // For the first two cases, the first fork will exit with + // EXIT_FAILURE, notifying us that startup failed. + // + // For the third case, the first fork will exit with EXIT_SUCCESS + // and we'll know that Xwayland started successfully. + + close(fd); struct wlr_xwayland_server *server = data; int stat_val = -1; @@ -236,8 +251,8 @@ static int xserver_handle_ready(int signal_number, void *data) { } wlr_log(WLR_DEBUG, "Xserver is ready"); - wl_event_source_remove(server->sigusr1_source); - server->sigusr1_source = NULL; + wl_event_source_remove(server->pipe_source); + server->pipe_source = NULL; struct wlr_xwayland_server_ready_event event = { .server = server, @@ -310,19 +325,33 @@ static bool server_start(struct wlr_xwayland_server *server) { server->client_destroy.notify = handle_client_destroy; wl_client_add_destroy_listener(server->client, &server->client_destroy); + int p[2]; + if (pipe(p) == -1) { + wlr_log_errno(WLR_ERROR, "pipe failed"); + server_finish_process(server); + return false; + } + if (!set_cloexec(p[1], true) || !set_cloexec(p[0], true)) { + wlr_log(WLR_ERROR, "Failed to set CLOEXEC on FD"); + server_finish_process(server); + return false; + } + struct wl_event_loop *loop = wl_display_get_event_loop(server->wl_display); - server->sigusr1_source = wl_event_loop_add_signal(loop, SIGUSR1, - xserver_handle_ready, server); + server->pipe_source = wl_event_loop_add_fd(loop, p[0], + WL_EVENT_READABLE, xserver_handle_ready, server); server->pid = fork(); if (server->pid < 0) { wlr_log_errno(WLR_ERROR, "fork failed"); + close(p[0]); + close(p[1]); server_finish_process(server); return false; } else if (server->pid == 0) { /* Double-fork, but we need to forward SIGUSR1 once Xserver(1) * is ready, or error if there was one. */ - pid_t ppid = getppid(); + close(p[0]); sigset_t sigset; sigemptyset(&sigset); sigaddset(&sigset, SIGUSR1); @@ -332,6 +361,7 @@ static bool server_start(struct wlr_xwayland_server *server) { pid_t pid = fork(); if (pid < 0) { wlr_log_errno(WLR_ERROR, "second fork failed"); + (void)!write(p[1], "\n", 1); _exit(EXIT_FAILURE); } else if (pid == 0) { exec_xwayland(server); @@ -339,8 +369,16 @@ static bool server_start(struct wlr_xwayland_server *server) { int sig; sigwait(&sigset, &sig); - kill(ppid, SIGUSR1); - wlr_log(WLR_DEBUG, "sent SIGUSR1 to process %d", ppid); + if (write(p[1], "\n", 1) < 1) { + // Note: if this write failed and we've leaked the write + // end of the pipe (due to a race between another thread + // exec'ing and our call to fcntl), then our handler will + // never wake up and never notice this failure. Hopefully + // that combination of events is extremely unlikely. This + // applies to the other write, too. + wlr_log_errno(WLR_ERROR, "write to pipe failed"); + _exit(EXIT_FAILURE); + } if (sig == SIGCHLD) { waitpid(pid, NULL, 0); _exit(EXIT_FAILURE); @@ -351,6 +389,7 @@ static bool server_start(struct wlr_xwayland_server *server) { /* close child fds */ /* remain managing x sockets for lazy start */ + close(p[1]); close(server->wl_fd[1]); safe_close(server->wm_fd[1]); server->wl_fd[1] = server->wm_fd[1] = -1; |