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// Copyright (C) 2023 David Edmundson <davidedmundson@kde.org>
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
#define _DEFAULT_SOURCE
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>
/* This is the size of the char array in struct sock_addr_un.
* No Wayland socket can be created with a path longer than this,
* including the null terminator.
*/
#ifndef UNIX_PATH_MAX
#define UNIX_PATH_MAX 108
#endif
#define LOCK_SUFFIX ".lock"
#define LOCK_SUFFIXLEN 5
struct wl_socket {
int fd;
int fd_lock;
struct sockaddr_un addr;
char lock_addr[UNIX_PATH_MAX + LOCK_SUFFIXLEN];
char display_name[16];
};
static struct wl_socket *wl_socket_alloc(void)
{
struct wl_socket *s;
s = malloc(sizeof *s);
if (!s)
return NULL;
s->fd = -1;
s->fd_lock = -1;
return s;
}
static int wl_socket_lock(struct wl_socket *socket)
{
struct stat socket_stat;
snprintf(socket->lock_addr, sizeof socket->lock_addr, "%s%s", socket->addr.sun_path, LOCK_SUFFIX);
// differening from kwin, we're back to setting CLOEXEC as we're all in process
socket->fd_lock = open(socket->lock_addr, O_CREAT | O_RDWR | O_CLOEXEC, (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP));
if (socket->fd_lock < 0) {
printf("unable to open lockfile %s check permissions\n", socket->lock_addr);
goto err;
}
if (flock(socket->fd_lock, LOCK_EX | LOCK_NB) < 0) {
printf("unable to lock lockfile %s, maybe another compositor is running\n", socket->lock_addr);
goto err_fd;
}
if (lstat(socket->addr.sun_path, &socket_stat) < 0) {
if (errno != ENOENT) {
printf("did not manage to stat file %s\n", socket->addr.sun_path);
goto err_fd;
}
} else if (socket_stat.st_mode & S_IWUSR || socket_stat.st_mode & S_IWGRP) {
unlink(socket->addr.sun_path);
}
return 0;
err_fd:
close(socket->fd_lock);
socket->fd_lock = -1;
err:
*socket->lock_addr = 0;
/* we did not set this value here, but without lock the
* socket won't be created anyway. This prevents the
* wl_socket_destroy from unlinking already existing socket
* created by other compositor */
*socket->addr.sun_path = 0;
return -1;
}
void wl_socket_destroy(struct wl_socket *s)
{
if (s->addr.sun_path[0])
unlink(s->addr.sun_path);
if (s->fd >= 0)
close(s->fd);
if (s->lock_addr[0])
unlink(s->lock_addr);
if (s->fd_lock >= 0)
close(s->fd_lock);
free(s);
}
const char *wl_socket_get_display_name(struct wl_socket *s)
{
return s->display_name;
}
int wl_socket_get_fd(struct wl_socket *s)
{
return s->fd;
}
struct wl_socket *wl_socket_create()
{
struct wl_socket *s;
int displayno = 0;
int name_size;
/* A reasonable number of maximum default sockets. If
* you need more than this, use the explicit add_socket API. */
const int MAX_DISPLAYNO = 32;
const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
if (!runtime_dir) {
printf("XDG_RUNTIME_DIR not set");
return NULL;
}
s = wl_socket_alloc();
if (s == NULL)
return NULL;
do {
snprintf(s->display_name, sizeof s->display_name, "wayland-%d", displayno);
s->addr.sun_family = AF_LOCAL;
name_size = snprintf(s->addr.sun_path, sizeof s->addr.sun_path, "%s/%s", runtime_dir, s->display_name) + 1;
assert(name_size > 0);
if (name_size > (int)sizeof s->addr.sun_path) {
goto fail;
}
if (wl_socket_lock(s) < 0)
continue;
s->fd = socket(PF_LOCAL, SOCK_STREAM, 0);
int size = SUN_LEN(&s->addr);
int ret = bind(s->fd, (struct sockaddr*)&s->addr, size);
if (ret < 0) {
goto fail;
}
ret = listen(s->fd, 128);
if (ret < 0) {
goto fail;
}
return s;
} while (displayno++ < MAX_DISPLAYNO);
fail:
wl_socket_destroy(s);
return NULL;
}
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