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Double-fork for xwayland execution

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The intermediate fork needs to wait for SIGUSR1 for when Xserver is
ready, or SIGCHLD if the exec didn't work out.

Also change the exit() to _exit() as that is apparently more appropriate
for forks (and waitpid's status was wrong without it for some reason)

Fixes #122.
This commit is contained in:
Dominique Martinet 2017-08-26 18:10:57 +02:00
parent 2f5ff45039
commit 871646d225
2 changed files with 59 additions and 26 deletions
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1
include/wlr/xwayland.h
View file

@ -1,7 +1,6 @@
#ifndef _WLR_XWAYLAND_H
#define _WLR_XWAYLAND_H
#include <time.h>
#include <sys/types.h>
#include <stdbool.h>
#include <wlr/types/wlr_compositor.h>
#include <xcb/xcb.h>

84
xwayland/xwayland.c
View file

@ -57,7 +57,7 @@ static void exec_xwayland(struct wlr_xwayland *wlr_xwayland) {
unset_cloexec(wlr_xwayland->x_fd[1]) ||
unset_cloexec(wlr_xwayland->wm_fd[1]) ||
unset_cloexec(wlr_xwayland->wl_fd[1])) {
exit(EXIT_FAILURE);
_exit(EXIT_FAILURE);
}
/* Make Xwayland signal us when it's ready */
@ -77,18 +77,18 @@ static void exec_xwayland(struct wlr_xwayland *wlr_xwayland) {
fill_arg(&cur_arg, "%d", wlr_xwayland->x_fd[1]) < 0 ||
fill_arg(&cur_arg, "%d", wlr_xwayland->wm_fd[1]) < 0) {
wlr_log_errno(L_ERROR, "alloc/print failure");
exit(EXIT_FAILURE);
_exit(EXIT_FAILURE);
}
const char *xdg_runtime = getenv("XDG_RUNTIME_DIR");
if (!xdg_runtime) {
wlr_log(L_ERROR, "XDG_RUNTIME_DIR is not set");
exit(EXIT_FAILURE);
_exit(EXIT_FAILURE);
}
if (clearenv()) {
wlr_log_errno(L_ERROR, "clearenv failed");
exit(EXIT_FAILURE);
_exit(EXIT_FAILURE);
}
setenv("XDG_RUNTIME_DIR", xdg_runtime, true);
char wayland_socket_str[16];
@ -150,12 +150,23 @@ static void wlr_xwayland_finish(struct wlr_xwayland *wlr_xwayland) {
* after we close our side of the wm/wl fds. This is more reliable
* than trying to kill something that might no longer be Xwayland.
*/
// TODO: figure how to wait for dying process though. Probably handle SIGCHILD
}
static int xserver_handle_ready(int signal_number, void *data) {
struct wlr_xwayland *wlr_xwayland = data;
int stat_val = -1;
while (waitpid(wlr_xwayland->pid, &stat_val, 0) < 0) {
if (errno == EINTR) {
continue;
}
wlr_log_errno(L_ERROR, "waitpid for Xwayland fork failed");
return 1;
}
if (stat_val) {
wlr_log(L_ERROR, "Xwayland startup failed, not setting up xwm");
return 1;
}
wlr_log(L_DEBUG, "Xserver is ready");
wlr_xwayland->xwm = xwm_create(wlr_xwayland);
@ -196,26 +207,6 @@ static bool wlr_xwayland_init(struct wlr_xwayland *wlr_xwayland,
return false;
}
if ((wlr_xwayland->pid = fork()) == 0) {
exec_xwayland(wlr_xwayland);
wlr_log_errno(L_ERROR, "execvpe failed");
exit(EXIT_FAILURE);
}
if (wlr_xwayland->pid < 0) {
wlr_log_errno(L_ERROR, "fork failed");
wlr_xwayland_finish(wlr_xwayland);
return false;
}
/* close child fds */
close(wlr_xwayland->x_fd[0]);
close(wlr_xwayland->x_fd[1]);
close(wlr_xwayland->wl_fd[1]);
close(wlr_xwayland->wm_fd[1]);
wlr_xwayland->x_fd[0] = wlr_xwayland->x_fd[1] = -1;
wlr_xwayland->wl_fd[1] = wlr_xwayland->wm_fd[1] = -1;
wlr_xwayland->server_start = time(NULL);
if (!(wlr_xwayland->client = wl_client_create(wl_display, wlr_xwayland->wl_fd[0]))) {
@ -231,6 +222,49 @@ static bool wlr_xwayland_init(struct wlr_xwayland *wlr_xwayland,
struct wl_event_loop *loop = wl_display_get_event_loop(wl_display);
wlr_xwayland->sigusr1_source = wl_event_loop_add_signal(loop, SIGUSR1, xserver_handle_ready, wlr_xwayland);
if ((wlr_xwayland->pid = fork()) == 0) {
/* Double-fork, but we need to forward SIGUSR1 once Xserver(1)
* is ready, or error if there was one. */
pid_t pid, ppid;
sigset_t sigset;
int sig;
ppid = getppid();
sigemptyset(&sigset);
sigaddset(&sigset, SIGUSR1);
sigaddset(&sigset, SIGCHLD);
sigprocmask(SIG_BLOCK, &sigset, NULL);
if ((pid = fork()) == 0) {
exec_xwayland(wlr_xwayland);
wlr_log_errno(L_ERROR, "failed to exec Xwayland");
_exit(EXIT_FAILURE);
}
if (pid < 0) {
wlr_log_errno(L_ERROR, "second fork failed");
_exit(EXIT_FAILURE);
}
sigwait(&sigset, &sig);
kill(ppid, SIGUSR1);
wlr_log(L_DEBUG, "sent SIGUSR1 to process %d", ppid);
if (sig == SIGCHLD) {
waitpid(pid, NULL, 0);
_exit(EXIT_FAILURE);
}
_exit(EXIT_SUCCESS);
}
if (wlr_xwayland->pid < 0) {
wlr_log_errno(L_ERROR, "fork failed");
wlr_xwayland_finish(wlr_xwayland);
return false;
}
/* close child fds */
close(wlr_xwayland->x_fd[0]);
close(wlr_xwayland->x_fd[1]);
close(wlr_xwayland->wl_fd[1]);
close(wlr_xwayland->wm_fd[1]);
wlr_xwayland->x_fd[0] = wlr_xwayland->x_fd[1] = -1;
wlr_xwayland->wl_fd[1] = wlr_xwayland->wm_fd[1] = -1;
return true;
}