i3/src/main.c

#undef I3__FILE__
#define I3__FILE__ "main.c"
/*
 * vim:ts=4:sw=4:expandtab
 *
 * i3 - an improved dynamic tiling window manager
 * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
 *
 * main.c: Initialization, main loop
 *
 */
#include <ev.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <libgen.h>
#include "all.h"
#include "shmlog.h"

#include "sd-daemon.h"

/* The original value of RLIMIT_CORE when i3 was started. We need to restore
 * this before starting any other process, since we set RLIMIT_CORE to
 * RLIM_INFINITY for i3 debugging versions. */
struct rlimit original_rlimit_core;

/** The number of file descriptors passed via socket activation. */
int listen_fds;

/* We keep the xcb_check watcher around to be able to enable and disable it
 * temporarily for drag_pointer(). */
static struct ev_check *xcb_check;

extern Con *focused;

char **start_argv;

xcb_connection_t *conn;
/* The screen (0 when you are using DISPLAY=:0) of the connection 'conn' */
int conn_screen;

/* Display handle for libstartup-notification */
SnDisplay *sndisplay;

/* The last timestamp we got from X11 (timestamps are included in some events
 * and are used for some things, like determining a unique ID in startup
 * notification). */
xcb_timestamp_t last_timestamp = XCB_CURRENT_TIME;

xcb_screen_t *root_screen;
xcb_window_t root;

/* Color depth, visual id and colormap to use when creating windows and
 * pixmaps. Will use 32 bit depth and an appropriate visual, if available,
 * otherwise the root window’s default (usually 24 bit TrueColor). */
uint8_t root_depth;
xcb_visualid_t visual_id;
xcb_colormap_t colormap;

struct ev_loop *main_loop;

xcb_key_symbols_t *keysyms;

/* Default shmlog size if not set by user. */
const int default_shmlog_size = 25 * 1024 * 1024;

/* The list of key bindings */
struct bindings_head *bindings;

/* The list of exec-lines */
struct autostarts_head autostarts = TAILQ_HEAD_INITIALIZER(autostarts);

/* The list of exec_always lines */
struct autostarts_always_head autostarts_always = TAILQ_HEAD_INITIALIZER(autostarts_always);

/* The list of assignments */
struct assignments_head assignments = TAILQ_HEAD_INITIALIZER(assignments);

/* The list of workspace assignments (which workspace should end up on which
 * output) */
struct ws_assignments_head ws_assignments = TAILQ_HEAD_INITIALIZER(ws_assignments);

/* We hope that those are supported and set them to true */
bool xcursor_supported = true;

/*
 * This callback is only a dummy, see xcb_prepare_cb and xcb_check_cb.
 * See also man libev(3): "ev_prepare" and "ev_check" - customise your event loop
 *
 */
static void xcb_got_event(EV_P_ struct ev_io *w, int revents) {
    /* empty, because xcb_prepare_cb and xcb_check_cb are used */
}

/*
 * Flush before blocking (and waiting for new events)
 *
 */
static void xcb_prepare_cb(EV_P_ ev_prepare *w, int revents) {
    xcb_flush(conn);
}

/*
 * Instead of polling the X connection socket we leave this to
 * xcb_poll_for_event() which knows better than we can ever know.
 *
 */
static void xcb_check_cb(EV_P_ ev_check *w, int revents) {
    xcb_generic_event_t *event;

    while ((event = xcb_poll_for_event(conn)) != NULL) {
        if (event->response_type == 0) {
            if (event_is_ignored(event->sequence, 0))
                DLOG("Expected X11 Error received for sequence %x\n", event->sequence);
            else {
                xcb_generic_error_t *error = (xcb_generic_error_t *)event;
                DLOG("X11 Error received (probably harmless)! sequence 0x%x, error_code = %d\n",
                     error->sequence, error->error_code);
            }
            free(event);
            continue;
        }

        /* Strip off the highest bit (set if the event is generated) */
        int type = (event->response_type & 0x7F);

        handle_event(type, event);

        free(event);
    }
}

/*
 * Enable or disable the main X11 event handling function.
 * This is used by drag_pointer() which has its own, modal event handler, which
 * takes precedence over the normal event handler.
 *
 */
void main_set_x11_cb(bool enable) {
    DLOG("Setting main X11 callback to enabled=%d\n", enable);
    if (enable) {
        ev_check_start(main_loop, xcb_check);
        /* Trigger the watcher explicitly to handle all remaining X11 events.
         * drag_pointer()’s event handler exits in the middle of the loop. */
        ev_feed_event(main_loop, xcb_check, 0);
    } else {
        ev_check_stop(main_loop, xcb_check);
    }
}

/*
 * Exit handler which destroys the main_loop. Will trigger cleanup handlers.
 *
 */
static void i3_exit(void) {
/* We need ev >= 4 for the following code. Since it is not *that* important (it
 * only makes sure that there are no i3-nagbar instances left behind) we still
 * support old systems with libev 3. */
#if EV_VERSION_MAJOR >= 4
    ev_loop_destroy(main_loop);
#endif

    if (*shmlogname != '\0') {
        fprintf(stderr, "Closing SHM log \"%s\"\n", shmlogname);
        fflush(stderr);
        shm_unlink(shmlogname);
    }
}

/*
 * (One-shot) Handler for all signals with default action "Term", see signal(7)
 *
 * Unlinks the SHM log and re-raises the signal.
 *
 */
static void handle_signal(int sig, siginfo_t *info, void *data) {
    if (*shmlogname != '\0') {
        shm_unlink(shmlogname);
    }
    raise(sig);
}

int main(int argc, char *argv[]) {
    /* Keep a symbol pointing to the I3_VERSION string constant so that we have
     * it in gdb backtraces. */
    const char *_i3_version __attribute__((unused)) = i3_version;
    char *override_configpath = NULL;
    bool autostart = true;
    char *layout_path = NULL;
    bool delete_layout_path = false;
    bool force_xinerama = false;
    char *fake_outputs = NULL;
    bool disable_signalhandler = false;
    bool only_check_config = false;
    static struct option long_options[] = {
        {"no-autostart", no_argument, 0, 'a'},
        {"config", required_argument, 0, 'c'},
        {"version", no_argument, 0, 'v'},
        {"moreversion", no_argument, 0, 'm'},
        {"more-version", no_argument, 0, 'm'},
        {"more_version", no_argument, 0, 'm'},
        {"help", no_argument, 0, 'h'},
        {"layout", required_argument, 0, 'L'},
        {"restart", required_argument, 0, 0},
        {"force-xinerama", no_argument, 0, 0},
        {"force_xinerama", no_argument, 0, 0},
        {"disable-signalhandler", no_argument, 0, 0},
        {"shmlog-size", required_argument, 0, 0},
        {"shmlog_size", required_argument, 0, 0},
        {"get-socketpath", no_argument, 0, 0},
        {"get_socketpath", no_argument, 0, 0},
        {"fake_outputs", required_argument, 0, 0},
        {"fake-outputs", required_argument, 0, 0},
        {"force-old-config-parser-v4.4-only", no_argument, 0, 0},
        {0, 0, 0, 0}};
    int option_index = 0, opt;

    setlocale(LC_ALL, "");

    /* Get the RLIMIT_CORE limit at startup time to restore this before
     * starting processes. */
    getrlimit(RLIMIT_CORE, &original_rlimit_core);

    /* Disable output buffering to make redirects in .xsession actually useful for debugging */
    if (!isatty(fileno(stdout)))
        setbuf(stdout, NULL);

    srand(time(NULL));

    /* Init logging *before* initializing debug_build to guarantee early
     * (file) logging. */
    init_logging();

    /* On release builds, disable SHM logging by default. */
    shmlog_size = (is_debug_build() || strstr(argv[0], "i3-with-shmlog") != NULL ? default_shmlog_size : 0);

    start_argv = argv;

    while ((opt = getopt_long(argc, argv, "c:CvmaL:hld:V", long_options, &option_index)) != -1) {
        switch (opt) {
            case 'a':
                LOG("Autostart disabled using -a\n");
                autostart = false;
                break;
            case 'L':
                FREE(layout_path);
                layout_path = sstrdup(optarg);
                delete_layout_path = false;
                break;
            case 'c':
                FREE(override_configpath);
                override_configpath = sstrdup(optarg);
                break;
            case 'C':
                LOG("Checking configuration file only (-C)\n");
                only_check_config = true;
                break;
            case 'v':
                printf("i3 version %s © 2009 Michael Stapelberg and contributors\n", i3_version);
                exit(EXIT_SUCCESS);
                break;
            case 'm':
                printf("Binary i3 version:  %s © 2009 Michael Stapelberg and contributors\n", i3_version);
                display_running_version();
                exit(EXIT_SUCCESS);
                break;
            case 'V':
                set_verbosity(true);
                break;
            case 'd':
                LOG("Enabling debug logging\n");
                set_debug_logging(true);
                break;
            case 'l':
                /* DEPRECATED, ignored for the next 3 versions (3.e, 3.f, 3.g) */
                break;
            case 0:
                if (strcmp(long_options[option_index].name, "force-xinerama") == 0 ||
                    strcmp(long_options[option_index].name, "force_xinerama") == 0) {
                    force_xinerama = true;
                    ELOG("Using Xinerama instead of RandR. This option should be "
                         "avoided at all cost because it does not refresh the list "
                         "of screens, so you cannot configure displays at runtime. "
                         "Please check if your driver really does not support RandR "
                         "and disable this option as soon as you can.\n");
                    break;
                } else if (strcmp(long_options[option_index].name, "disable-signalhandler") == 0) {
                    disable_signalhandler = true;
                    break;
                } else if (strcmp(long_options[option_index].name, "get-socketpath") == 0 ||
                           strcmp(long_options[option_index].name, "get_socketpath") == 0) {
                    char *socket_path = root_atom_contents("I3_SOCKET_PATH", NULL, 0);
                    if (socket_path) {
                        printf("%s\n", socket_path);
                        exit(EXIT_SUCCESS);
                    }

                    exit(EXIT_FAILURE);
                } else if (strcmp(long_options[option_index].name, "shmlog-size") == 0 ||
                           strcmp(long_options[option_index].name, "shmlog_size") == 0) {
                    shmlog_size = atoi(optarg);
                    /* Re-initialize logging immediately to get as many
                     * logmessages as possible into the SHM log. */
                    init_logging();
                    LOG("Limiting SHM log size to %d bytes\n", shmlog_size);
                    break;
                } else if (strcmp(long_options[option_index].name, "restart") == 0) {
                    FREE(layout_path);
                    layout_path = sstrdup(optarg);
                    delete_layout_path = true;
                    break;
                } else if (strcmp(long_options[option_index].name, "fake-outputs") == 0 ||
                           strcmp(long_options[option_index].name, "fake_outputs") == 0) {
                    LOG("Initializing fake outputs: %s\n", optarg);
                    fake_outputs = sstrdup(optarg);
                    break;
                } else if (strcmp(long_options[option_index].name, "force-old-config-parser-v4.4-only") == 0) {
                    ELOG("You are passing --force-old-config-parser-v4.4-only, but that flag was removed by now.\n");
                    break;
                }
            /* fall-through */
            default:
                fprintf(stderr, "Usage: %s [-c configfile] [-d all] [-a] [-v] [-V] [-C]\n", argv[0]);
                fprintf(stderr, "\n");
                fprintf(stderr, "\t-a          disable autostart ('exec' lines in config)\n");
                fprintf(stderr, "\t-c <file>   use the provided configfile instead\n");
                fprintf(stderr, "\t-C          validate configuration file and exit\n");
                fprintf(stderr, "\t-d all      enable debug output\n");
                fprintf(stderr, "\t-L <file>   path to the serialized layout during restarts\n");
                fprintf(stderr, "\t-v          display version and exit\n");
                fprintf(stderr, "\t-V          enable verbose mode\n");
                fprintf(stderr, "\n");
                fprintf(stderr, "\t--force-xinerama\n"
                                "\tUse Xinerama instead of RandR.\n"
                                "\tThis option should only be used if you are stuck with the\n"
                                "\told nVidia closed source driver (older than 302.17), which does\n"
                                "\tnot support RandR.\n");
                fprintf(stderr, "\n");
                fprintf(stderr, "\t--get-socketpath\n"
                                "\tRetrieve the i3 IPC socket path from X11, print it, then exit.\n");
                fprintf(stderr, "\n");
                fprintf(stderr, "\t--shmlog-size <limit>\n"
                                "\tLimits the size of the i3 SHM log to <limit> bytes. Setting this\n"
                                "\tto 0 disables SHM logging entirely.\n"
                                "\tThe default is %d bytes.\n",
                        shmlog_size);
                fprintf(stderr, "\n");
                fprintf(stderr, "If you pass plain text arguments, i3 will interpret them as a command\n"
                                "to send to a currently running i3 (like i3-msg). This allows you to\n"
                                "use nice and logical commands, such as:\n"
                                "\n"
                                "\ti3 border none\n"
                                "\ti3 floating toggle\n"
                                "\ti3 kill window\n"
                                "\n");
                exit(EXIT_FAILURE);
        }
    }

    if (only_check_config) {
        exit(parse_configuration(override_configpath, false) ? 0 : 1);
    }

    /* If the user passes more arguments, we act like i3-msg would: Just send
     * the arguments as an IPC message to i3. This allows for nice semantic
     * commands such as 'i3 border none'. */
    if (optind < argc) {
        /* We enable verbose mode so that the user knows what’s going on.
         * This should make it easier to find mistakes when the user passes
         * arguments by mistake. */
        set_verbosity(true);

        LOG("Additional arguments passed. Sending them as a command to i3.\n");
        char *payload = NULL;
        while (optind < argc) {
            if (!payload) {
                payload = sstrdup(argv[optind]);
            } else {
                char *both;
                sasprintf(&both, "%s %s", payload, argv[optind]);
                free(payload);
                payload = both;
            }
            optind++;
        }
        DLOG("Command is: %s (%zd bytes)\n", payload, strlen(payload));
        char *socket_path = root_atom_contents("I3_SOCKET_PATH", NULL, 0);
        if (!socket_path) {
            ELOG("Could not get i3 IPC socket path\n");
            return 1;
        }

        int sockfd = socket(AF_LOCAL, SOCK_STREAM, 0);
        if (sockfd == -1)
            err(EXIT_FAILURE, "Could not create socket");

        struct sockaddr_un addr;
        memset(&addr, 0, sizeof(struct sockaddr_un));
        addr.sun_family = AF_LOCAL;
        strncpy(addr.sun_path, socket_path, sizeof(addr.sun_path) - 1);
        if (connect(sockfd, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un)) < 0)
            err(EXIT_FAILURE, "Could not connect to i3");

        if (ipc_send_message(sockfd, strlen(payload), I3_IPC_MESSAGE_TYPE_COMMAND,
                             (uint8_t *)payload) == -1)
            err(EXIT_FAILURE, "IPC: write()");

        uint32_t reply_length;
        uint32_t reply_type;
        uint8_t *reply;
        int ret;
        if ((ret = ipc_recv_message(sockfd, &reply_type, &reply_length, &reply)) != 0) {
            if (ret == -1)
                err(EXIT_FAILURE, "IPC: read()");
            return 1;
        }
        if (reply_type != I3_IPC_MESSAGE_TYPE_COMMAND)
            errx(EXIT_FAILURE, "IPC: received reply of type %d but expected %d (COMMAND)", reply_type, I3_IPC_MESSAGE_TYPE_COMMAND);
        printf("%.*s\n", reply_length, reply);
        return 0;
    }

    /* Enable logging to handle the case when the user did not specify --shmlog-size */
    init_logging();

    /* Try to enable core dumps by default when running a debug build */
    if (is_debug_build()) {
        struct rlimit limit = {RLIM_INFINITY, RLIM_INFINITY};
        setrlimit(RLIMIT_CORE, &limit);

        /* The following code is helpful, but not required. We thus don’t pay
         * much attention to error handling, non-linux or other edge cases. */
        LOG("CORE DUMPS: You are running a development version of i3, so coredumps were automatically enabled (ulimit -c unlimited).\n");
        size_t cwd_size = 1024;
        char *cwd = smalloc(cwd_size);
        char *cwd_ret;
        while ((cwd_ret = getcwd(cwd, cwd_size)) == NULL && errno == ERANGE) {
            cwd_size = cwd_size * 2;
            cwd = srealloc(cwd, cwd_size);
        }
        if (cwd_ret != NULL)
            LOG("CORE DUMPS: Your current working directory is \"%s\".\n", cwd);
        int patternfd;
        if ((patternfd = open("/proc/sys/kernel/core_pattern", O_RDONLY)) >= 0) {
            memset(cwd, '\0', cwd_size);
            if (read(patternfd, cwd, cwd_size) > 0)
                /* a trailing newline is included in cwd */
                LOG("CORE DUMPS: Your core_pattern is: \"%s\".\n", cwd);
            close(patternfd);
        }
        free(cwd);
    }

    LOG("i3 %s starting\n", i3_version);

    conn = xcb_connect(NULL, &conn_screen);
    if (xcb_connection_has_error(conn))
        errx(EXIT_FAILURE, "Cannot open display\n");

    sndisplay = sn_xcb_display_new(conn, NULL, NULL);

    /* Initialize the libev event loop. This needs to be done before loading
     * the config file because the parser will install an ev_child watcher
     * for the nagbar when config errors are found. */
    main_loop = EV_DEFAULT;
    if (main_loop == NULL)
        die("Could not initialize libev. Bad LIBEV_FLAGS?\n");

    root_screen = xcb_aux_get_screen(conn, conn_screen);
    root = root_screen->root;

/* Place requests for the atoms we need as soon as possible */
#define xmacro(atom) \
    xcb_intern_atom_cookie_t atom##_cookie = xcb_intern_atom(conn, 0, strlen(#atom), #atom);
#include "atoms.xmacro"
#undef xmacro

    /* By default, we use the same depth and visual as the root window, which
     * usually is TrueColor (24 bit depth) and the corresponding visual.
     * However, we also check if a 32 bit depth and visual are available (for
     * transparency) and use it if so. */
    root_depth = root_screen->root_depth;
    visual_id = root_screen->root_visual;
    colormap = root_screen->default_colormap;

    DLOG("root_depth = %d, visual_id = 0x%08x.\n", root_depth, visual_id);
    DLOG("root_screen->height_in_pixels = %d, root_screen->height_in_millimeters = %d, dpi = %d\n",
         root_screen->height_in_pixels, root_screen->height_in_millimeters,
         (int)((double)root_screen->height_in_pixels * 25.4 / (double)root_screen->height_in_millimeters));
    DLOG("One logical pixel corresponds to %d physical pixels on this display.\n", logical_px(1));

    xcb_get_geometry_cookie_t gcookie = xcb_get_geometry(conn, root);
    xcb_query_pointer_cookie_t pointercookie = xcb_query_pointer(conn, root);

/* Setup NetWM atoms */
#define xmacro(name)                                                                       \
    do {                                                                                   \
        xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(conn, name##_cookie, NULL); \
        if (!reply) {                                                                      \
            ELOG("Could not get atom " #name "\n");                                        \
            exit(-1);                                                                      \
        }                                                                                  \
        A_##name = reply->atom;                                                            \
        free(reply);                                                                       \
    } while (0);
#include "atoms.xmacro"
#undef xmacro

    load_configuration(conn, override_configpath, false);

    if (config.ipc_socket_path == NULL) {
        /* Fall back to a file name in /tmp/ based on the PID */
        if ((config.ipc_socket_path = getenv("I3SOCK")) == NULL)
            config.ipc_socket_path = get_process_filename("ipc-socket");
        else
            config.ipc_socket_path = sstrdup(config.ipc_socket_path);
    }

    xcb_void_cookie_t cookie;
    cookie = xcb_change_window_attributes_checked(conn, root, XCB_CW_EVENT_MASK, (uint32_t[]){ROOT_EVENT_MASK});
    check_error(conn, cookie, "Another window manager seems to be running");

    xcb_get_geometry_reply_t *greply = xcb_get_geometry_reply(conn, gcookie, NULL);
    if (greply == NULL) {
        ELOG("Could not get geometry of the root window, exiting\n");
        return 1;
    }
    DLOG("root geometry reply: (%d, %d) %d x %d\n", greply->x, greply->y, greply->width, greply->height);

    xcursor_load_cursors();

    /* Set a cursor for the root window (otherwise the root window will show no
       cursor until the first client is launched). */
    if (xcursor_supported)
        xcursor_set_root_cursor(XCURSOR_CURSOR_POINTER);
    else
        xcb_set_root_cursor(XCURSOR_CURSOR_POINTER);

    const xcb_query_extension_reply_t *extreply;
    extreply = xcb_get_extension_data(conn, &xcb_xkb_id);
    if (!extreply->present) {
        DLOG("xkb is not present on this server\n");
    } else {
        DLOG("initializing xcb-xkb\n");
        xcb_xkb_use_extension(conn, XCB_XKB_MAJOR_VERSION, XCB_XKB_MINOR_VERSION);
        xcb_xkb_select_events(conn,
                              XCB_XKB_ID_USE_CORE_KBD,
                              XCB_XKB_EVENT_TYPE_STATE_NOTIFY | XCB_XKB_EVENT_TYPE_MAP_NOTIFY | XCB_XKB_EVENT_TYPE_NEW_KEYBOARD_NOTIFY,
                              0,
                              XCB_XKB_EVENT_TYPE_STATE_NOTIFY | XCB_XKB_EVENT_TYPE_MAP_NOTIFY | XCB_XKB_EVENT_TYPE_NEW_KEYBOARD_NOTIFY,
                              0xff,
                              0xff,
                              NULL);
        xkb_base = extreply->first_event;
    }

    restore_connect();

    property_handlers_init();

    ewmh_setup_hints();

    keysyms = xcb_key_symbols_alloc(conn);

    xcb_numlock_mask = aio_get_mod_mask_for(XCB_NUM_LOCK, keysyms);

    translate_keysyms();
    grab_all_keys(conn, false);

    bool needs_tree_init = true;
    if (layout_path) {
        LOG("Trying to restore the layout from \"%s\".\n", layout_path);
        needs_tree_init = !tree_restore(layout_path, greply);
        if (delete_layout_path) {
            unlink(layout_path);
            const char *dir = dirname(layout_path);
            /* possibly fails with ENOTEMPTY if there are files (or
             * sockets) left. */
            rmdir(dir);
        }
        free(layout_path);
    }
    if (needs_tree_init)
        tree_init(greply);

    free(greply);

    /* Setup fake outputs for testing */
    if (fake_outputs == NULL && config.fake_outputs != NULL)
        fake_outputs = config.fake_outputs;

    if (fake_outputs != NULL) {
        fake_outputs_init(fake_outputs);
        FREE(fake_outputs);
        config.fake_outputs = NULL;
    } else if (force_xinerama || config.force_xinerama) {
        /* Force Xinerama (for drivers which don't support RandR yet, esp. the
         * nVidia binary graphics driver), when specified either in the config
         * file or on command-line */
        xinerama_init();
    } else {
        DLOG("Checking for XRandR...\n");
        randr_init(&randr_base);
    }

    scratchpad_fix_resolution();

    xcb_query_pointer_reply_t *pointerreply;
    Output *output = NULL;
    if (!(pointerreply = xcb_query_pointer_reply(conn, pointercookie, NULL))) {
        ELOG("Could not query pointer position, using first screen\n");
    } else {
        DLOG("Pointer at %d, %d\n", pointerreply->root_x, pointerreply->root_y);
        output = get_output_containing(pointerreply->root_x, pointerreply->root_y);
        if (!output) {
            ELOG("ERROR: No screen at (%d, %d), starting on the first screen\n",
                 pointerreply->root_x, pointerreply->root_y);
            output = get_first_output();
            if (!output)
                die("No usable outputs available.\n");
        }

        con_focus(con_descend_focused(output_get_content(output->con)));
    }

    tree_render();

    /* Create the UNIX domain socket for IPC */
    int ipc_socket = ipc_create_socket(config.ipc_socket_path);
    if (ipc_socket == -1) {
        ELOG("Could not create the IPC socket, IPC disabled\n");
    } else {
        struct ev_io *ipc_io = scalloc(1, sizeof(struct ev_io));
        ev_io_init(ipc_io, ipc_new_client, ipc_socket, EV_READ);
        ev_io_start(main_loop, ipc_io);
    }

    /* Also handle the UNIX domain sockets passed via socket activation. The
     * parameter 1 means "remove the environment variables", we don’t want to
     * pass these to child processes. */
    listen_fds = sd_listen_fds(0);
    if (listen_fds < 0)
        ELOG("socket activation: Error in sd_listen_fds\n");
    else if (listen_fds == 0)
        DLOG("socket activation: no sockets passed\n");
    else {
        int flags;
        for (int fd = SD_LISTEN_FDS_START;
             fd < (SD_LISTEN_FDS_START + listen_fds);
             fd++) {
            DLOG("socket activation: also listening on fd %d\n", fd);

            /* sd_listen_fds() enables FD_CLOEXEC by default.
             * However, we need to keep the file descriptors open for in-place
             * restarting, therefore we explicitly disable FD_CLOEXEC. */
            if ((flags = fcntl(fd, F_GETFD)) < 0 ||
                fcntl(fd, F_SETFD, flags & ~FD_CLOEXEC) < 0) {
                ELOG("Could not disable FD_CLOEXEC on fd %d\n", fd);
            }

            struct ev_io *ipc_io = scalloc(1, sizeof(struct ev_io));
            ev_io_init(ipc_io, ipc_new_client, fd, EV_READ);
            ev_io_start(main_loop, ipc_io);
        }
    }

    /* Set up i3 specific atoms like I3_SOCKET_PATH and I3_CONFIG_PATH */
    x_set_i3_atoms();
    ewmh_update_workarea();

    /* Set the ewmh desktop properties. */
    ewmh_update_current_desktop();
    ewmh_update_number_of_desktops();
    ewmh_update_desktop_names();
    ewmh_update_desktop_viewport();

    struct ev_io *xcb_watcher = scalloc(1, sizeof(struct ev_io));
    xcb_check = scalloc(1, sizeof(struct ev_check));
    struct ev_prepare *xcb_prepare = scalloc(1, sizeof(struct ev_prepare));

    ev_io_init(xcb_watcher, xcb_got_event, xcb_get_file_descriptor(conn), EV_READ);
    ev_io_start(main_loop, xcb_watcher);

    ev_check_init(xcb_check, xcb_check_cb);
    ev_check_start(main_loop, xcb_check);

    ev_prepare_init(xcb_prepare, xcb_prepare_cb);
    ev_prepare_start(main_loop, xcb_prepare);

    xcb_flush(conn);

    /* What follows is a fugly consequence of X11 protocol race conditions like
     * the following: In an i3 in-place restart, i3 will reparent all windows
     * to the root window, then exec() itself. In the new process, it calls
     * manage_existing_windows. However, in case any application sent a
     * generated UnmapNotify message to the WM (as GIMP does), this message
     * will be handled by i3 *after* managing the window, thus i3 thinks the
     * window just closed itself. In reality, the message was sent in the time
     * period where i3 wasn’t running yet.
     *
     * To prevent this, we grab the server (disables processing of any other
     * connections), then discard all pending events (since we didn’t do
     * anything, there cannot be any meaningful responses), then ungrab the
     * server. */
    xcb_grab_server(conn);
    {
        xcb_aux_sync(conn);
        xcb_generic_event_t *event;
        while ((event = xcb_poll_for_event(conn)) != NULL) {
            if (event->response_type == 0) {
                free(event);
                continue;
            }

            /* Strip off the highest bit (set if the event is generated) */
            int type = (event->response_type & 0x7F);

            /* We still need to handle MapRequests which are sent in the
             * timespan starting from when we register as a window manager and
             * this piece of code which drops events. */
            if (type == XCB_MAP_REQUEST)
                handle_event(type, event);

            free(event);
        }
        manage_existing_windows(root);
    }
    xcb_ungrab_server(conn);

    if (autostart) {
        LOG("This is not an in-place restart, copying root window contents to a pixmap\n");
        xcb_screen_t *root = xcb_aux_get_screen(conn, conn_screen);
        uint16_t width = root->width_in_pixels;
        uint16_t height = root->height_in_pixels;
        xcb_pixmap_t pixmap = xcb_generate_id(conn);
        xcb_gcontext_t gc = xcb_generate_id(conn);

        xcb_create_pixmap(conn, root->root_depth, pixmap, root->root, width, height);

        xcb_create_gc(conn, gc, root->root,
                      XCB_GC_FUNCTION | XCB_GC_PLANE_MASK | XCB_GC_FILL_STYLE | XCB_GC_SUBWINDOW_MODE,
                      (uint32_t[]){XCB_GX_COPY, ~0, XCB_FILL_STYLE_SOLID, XCB_SUBWINDOW_MODE_INCLUDE_INFERIORS});

        xcb_copy_area(conn, root->root, pixmap, gc, 0, 0, 0, 0, width, height);
        xcb_change_window_attributes_checked(conn, root->root, XCB_CW_BACK_PIXMAP, (uint32_t[]){pixmap});
        xcb_flush(conn);
        xcb_free_gc(conn, gc);
        xcb_free_pixmap(conn, pixmap);
    }

    struct sigaction action;

    action.sa_sigaction = handle_signal;
    action.sa_flags = SA_NODEFER | SA_RESETHAND | SA_SIGINFO;
    sigemptyset(&action.sa_mask);

    if (!disable_signalhandler)
        setup_signal_handler();
    else {
        /* Catch all signals with default action "Core", see signal(7) */
        if (sigaction(SIGQUIT, &action, NULL) == -1 ||
            sigaction(SIGILL, &action, NULL) == -1 ||
            sigaction(SIGABRT, &action, NULL) == -1 ||
            sigaction(SIGFPE, &action, NULL) == -1 ||
            sigaction(SIGSEGV, &action, NULL) == -1)
            ELOG("Could not setup signal handler.\n");
    }

    /* Catch all signals with default action "Term", see signal(7) */
    if (sigaction(SIGHUP, &action, NULL) == -1 ||
        sigaction(SIGINT, &action, NULL) == -1 ||
        sigaction(SIGALRM, &action, NULL) == -1 ||
        sigaction(SIGUSR1, &action, NULL) == -1 ||
        sigaction(SIGUSR2, &action, NULL) == -1)
        ELOG("Could not setup signal handler.\n");

    /* Ignore SIGPIPE to survive errors when an IPC client disconnects
     * while we are sending them a message */
    signal(SIGPIPE, SIG_IGN);

    /* Autostarting exec-lines */
    if (autostart) {
        struct Autostart *exec;
        TAILQ_FOREACH(exec, &autostarts, autostarts) {
            LOG("auto-starting %s\n", exec->command);
            start_application(exec->command, exec->no_startup_id);
        }
    }

    /* Autostarting exec_always-lines */
    struct Autostart *exec_always;
    TAILQ_FOREACH(exec_always, &autostarts_always, autostarts_always) {
        LOG("auto-starting (always!) %s\n", exec_always->command);
        start_application(exec_always->command, exec_always->no_startup_id);
    }

    /* Start i3bar processes for all configured bars */
    Barconfig *barconfig;
    TAILQ_FOREACH(barconfig, &barconfigs, configs) {
        char *command = NULL;
        sasprintf(&command, "%s --bar_id=%s --socket=\"%s\"",
                  barconfig->i3bar_command ? barconfig->i3bar_command : "i3bar",
                  barconfig->id, current_socketpath);
        LOG("Starting bar process: %s\n", command);
        start_application(command, true);
        free(command);
    }

    /* Make sure to destroy the event loop to invoke the cleeanup callbacks
     * when calling exit() */
    atexit(i3_exit);

    ev_loop(main_loop, 0);
}