Implement a visual unlock indicator

1 files changed, 378 insertions, 66 deletions

diff --git a/i3lock.c b/i3lock.c
index 2a43750..af93a1e 100644
--- a/i3lock.c
+++ b/i3lock.c
@@ -22,6 +22,9 @@
 #include <X11/keysym.h>
 #include <getopt.h>
 #include <string.h>
+#include <math.h>
+#include <ev.h>
+
 
 #ifndef NOLIBCAIRO
 #include <cairo.h>
@@ -33,7 +36,16 @@
 #include "xcb.h"
 #include "cursors.h"
 
+#define BUTTON_RADIUS 90
+#define BUTTON_SPACE (BUTTON_RADIUS + 5)
+#define BUTTON_CENTER (BUTTON_RADIUS + 5)
+#define BUTTON_DIAMETER (5 * BUTTON_SPACE)
+
+static char color[7] = "ffffff";
+static uint32_t last_resolution[2];
 static xcb_connection_t *conn;
+static xcb_window_t win;
+static xcb_visualtype_t *vistype;
 static xcb_cursor_t cursor;
 static xcb_key_symbols_t *symbols;
 static xcb_screen_t *scr;
@@ -47,6 +59,26 @@ static int modeswitchmask;
 static int numlockmask;
 static bool beep = false;
 static bool debug_mode = false;
+static bool dpms = false;
+static bool unlock_indicator = true;
+static struct ev_loop *main_loop;
+static struct ev_timer *clear_pam_wrong_timeout;
+static struct ev_timer *clear_indicator_timeout;
+
+static enum {
+    STATE_STARTED = 0,          /* default state */
+    STATE_KEY_PRESSED = 1,      /* key was pressed, show unlock indicator */
+    STATE_KEY_ACTIVE = 2,       /* a key was pressed recently, highlight part
+                                   of the unlock indicator. */
+    STATE_BACKSPACE_ACTIVE = 3  /* backspace was pressed recently, highlight
+                                   part of the unlock indicator in red. */
+} unlock_state;
+
+static enum {
+    STATE_PAM_IDLE = 0,         /* no PAM interaction at the moment */
+    STATE_PAM_VERIFY = 1,       /* currently verifying the password via PAM */
+    STATE_PAM_WRONG = 2         /* the password was wrong */
+} pam_state;
 
 #define DEBUG(fmt, ...) do { \
     if (debug_mode) \
@@ -63,43 +95,234 @@ static bool tile = false;
  * resolution and returns it.
  *
  */
-xcb_pixmap_t draw_image(xcb_visualtype_t *vistype, u_int32_t* resolution, char* color) {
+static xcb_pixmap_t draw_image(xcb_visualtype_t *vistype, u_int32_t* resolution) {
     xcb_pixmap_t bg_pixmap = XCB_NONE;
 
 #ifndef NOLIBCAIRO
-    if (!img)
-        return bg_pixmap;
-
     bg_pixmap = create_bg_pixmap(conn, scr, resolution, color);
     /* Initialize cairo */
     cairo_surface_t *output;
     output = cairo_xcb_surface_create(conn, bg_pixmap, vistype,
              resolution[0], resolution[1]);
     cairo_t *ctx = cairo_create(output);
-    if (!tile) {
-        cairo_set_source_surface(ctx, img, 0, 0);
-        cairo_paint(ctx);
-    } else {
-        /* create a pattern and fill a rectangle as big as the screen */
-        cairo_pattern_t *pattern;
-        pattern = cairo_pattern_create_for_surface(img);
-        cairo_set_source(ctx, pattern);
-        cairo_pattern_set_extend(pattern, CAIRO_EXTEND_REPEAT);
-        cairo_rectangle(ctx, 0, 0, resolution[0], resolution[1]);
-        cairo_fill(ctx);
-        cairo_pattern_destroy(pattern);
+    if (img) {
+        if (!tile) {
+            cairo_set_source_surface(ctx, img, 0, 0);
+            cairo_paint(ctx);
+        } else {
+            /* create a pattern and fill a rectangle as big as the screen */
+            cairo_pattern_t *pattern;
+            pattern = cairo_pattern_create_for_surface(img);
+            cairo_set_source(ctx, pattern);
+            cairo_pattern_set_extend(pattern, CAIRO_EXTEND_REPEAT);
+            cairo_rectangle(ctx, 0, 0, resolution[0], resolution[1]);
+            cairo_fill(ctx);
+            cairo_pattern_destroy(pattern);
+        }
+    }
+
+    if (unlock_state >= STATE_KEY_PRESSED && unlock_indicator) {
+        cairo_pattern_t *outer_pat = NULL;
+
+        outer_pat = cairo_pattern_create_linear(0, 0, 0, BUTTON_DIAMETER);
+        switch (pam_state) {
+            case STATE_PAM_VERIFY:
+                cairo_pattern_add_color_stop_rgb(outer_pat, 0, 139.0/255, 0, 250.0/255);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 1, 51.0/255, 0, 250.0/255);
+                break;
+            case STATE_PAM_WRONG:
+                cairo_pattern_add_color_stop_rgb(outer_pat, 0, 255.0/250, 139.0/255, 0);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 1, 125.0/255, 51.0/255, 0);
+                break;
+            case STATE_PAM_IDLE:
+                cairo_pattern_add_color_stop_rgb(outer_pat, 0, 139.0/255, 125.0/255, 0);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 1, 51.0/255, 125.0/255, 0);
+                break;
+        }
+
+        /* Draw a (centered) circle with transparent background. */
+        cairo_set_line_width(ctx, 10.0);
+        cairo_arc(ctx,
+                  (resolution[0] / 2) /* x */,
+                  (resolution[1] / 2) /* y */,
+                  BUTTON_RADIUS /* radius */,
+                  0 /* start */,
+                  2 * M_PI /* end */);
+
+        /* Use the appropriate color for the different PAM states
+         * (currently verifying, wrong password, or default) */
+        switch (pam_state) {
+            case STATE_PAM_VERIFY:
+                cairo_set_source_rgba(ctx, 0, 114.0/255, 255.0/255, 0.75);
+                break;
+            case STATE_PAM_WRONG:
+                cairo_set_source_rgba(ctx, 250.0/255, 0, 0, 0.75);
+                break;
+            default:
+                cairo_set_source_rgba(ctx, 0, 0, 0, 0.75);
+                break;
+        }
+        cairo_fill_preserve(ctx);
+        cairo_set_source(ctx, outer_pat);
+        cairo_stroke(ctx);
+
+        /* Draw an inner seperator line. */
+        cairo_set_source_rgb(ctx, 0, 0, 0);
+        cairo_set_line_width(ctx, 2.0);
+        cairo_arc(ctx,
+                  (resolution[0] / 2) /* x */,
+                  (resolution[1] / 2) /* y */,
+                  BUTTON_RADIUS - 5 /* radius */,
+                  0,
+                  2 * M_PI);
+        cairo_stroke(ctx);
+
+        cairo_set_line_width(ctx, 10.0);
+
+        /* Display a (centered) text of the current PAM state. */
+        char *text = NULL;
+        switch (pam_state) {
+            case STATE_PAM_VERIFY:
+                text = "verifying…";
+                break;
+            case STATE_PAM_WRONG:
+                text = "wrong!";
+                break;
+            default:
+                break;
+        }
+
+        if (text) {
+            cairo_text_extents_t extents;
+            double x, y;
+
+            cairo_set_source_rgb(ctx, 0, 0, 0);
+            cairo_set_font_size(ctx, 28.0);
+
+            cairo_text_extents(ctx, text, &extents);
+            x = (resolution[0] / 2.0) - ((extents.width / 2) + extents.x_bearing);
+            y = (resolution[1] / 2.0) - ((extents.height / 2) + extents.y_bearing);
+
+            cairo_move_to(ctx, x, y);
+            cairo_show_text(ctx, text);
+            cairo_close_path(ctx);
+        }
+
+        /* After the user pressed any valid key or the backspace key, we
+         * highlight a random part of the unlock indicator to confirm this
+         * keypress. */
+        if (unlock_state == STATE_KEY_ACTIVE ||
+            unlock_state == STATE_BACKSPACE_ACTIVE) {
+            cairo_new_sub_path(ctx);
+            double highlight_start = (rand() % (int)(2 * M_PI * 100)) / 100.0;
+            DEBUG("Highlighting part %.2f\n", highlight_start);
+            cairo_arc(ctx, resolution[0] / 2 /* x */, resolution[1] / 2 /* y */,
+                      BUTTON_RADIUS /* radius */, highlight_start,
+                      highlight_start + (M_PI / 3.0));
+            if (unlock_state == STATE_KEY_ACTIVE) {
+                /* For normal keys, we use a lighter green. */
+                outer_pat = cairo_pattern_create_linear(0, 0, 0, BUTTON_DIAMETER);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 0, 139.0/255, 219.0/255, 0);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 1, 51.0/255, 219.0/255, 0);
+            } else {
+                /* For backspace, we use red. */
+                outer_pat = cairo_pattern_create_linear(0, 0, 0, BUTTON_DIAMETER);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 0, 219.0/255, 139.0/255, 0);
+                cairo_pattern_add_color_stop_rgb(outer_pat, 1, 219.0/255, 51.0/255, 0);
+            }
+            cairo_set_source(ctx, outer_pat);
+            cairo_stroke(ctx);
+
+            /* Draw two little separators for the highlighted part of the
+             * unlock indicator. */
+            cairo_set_source_rgb(ctx, 0, 0, 0);
+            cairo_arc(ctx,
+                      (resolution[0] / 2) /* x */,
+                      (resolution[1] / 2) /* y */,
+                      BUTTON_RADIUS /* radius */,
+                      highlight_start /* start */,
+                      highlight_start + (M_PI / 128.0) /* end */);
+            cairo_stroke(ctx);
+            cairo_arc(ctx,
+                      (resolution[0] / 2) /* x */,
+                      (resolution[1] / 2) /* y */,
+                      BUTTON_RADIUS /* radius */,
+                      highlight_start + (M_PI / 3.0) /* start */,
+                      (highlight_start + (M_PI / 3.0)) + (M_PI / 128.0) /* end */);
+            cairo_stroke(ctx);
+        }
     }
+
     cairo_surface_destroy(output);
     cairo_destroy(ctx);
 #endif
     return bg_pixmap;
 }
 
+/*
+ * Calls draw_image on a new pixmap and swaps that with the current pixmap
+ *
+ */
+static void redraw_screen() {
+    xcb_pixmap_t bg_pixmap = draw_image(vistype, last_resolution);
+    xcb_change_window_attributes(conn, win, XCB_CW_BACK_PIXMAP, (uint32_t[1]){ bg_pixmap });
+    /* XXX: Possible optimization: Only update the area in the middle of the
+     * screen instead of the whole screen. */
+    xcb_clear_area(conn, 0, win, 0, 0, scr->width_in_pixels, scr->height_in_pixels);
+    xcb_flush(conn);
+}
+
+/*
+ * Resets pam_state to STATE_PAM_IDLE 2 seconds after an unsuccesful
+ * authentication event.
+ *
+ */
+static void clear_pam_wrong(EV_P_ ev_timer *w, int revents) {
+    pam_state = STATE_PAM_IDLE;
+    unlock_state = STATE_STARTED;
+    redraw_screen();
+}
+
+/*
+ * Hides the unlock indicator completely when there is no content in the
+ * password buffer.
+ *
+ */
+static void clear_indicator(EV_P_ ev_timer *w, int revents) {
+    DEBUG("Clear indicator\n");
+    unlock_state = STATE_STARTED;
+    redraw_screen();
+}
+
+/*
+ * (Re-)starts the clear_indicator timeout. Called after pressing backspace or
+ * after an unsuccessful authentication attempt.
+ *
+ */
+static void start_clear_indicator_timeout() {
+    if (clear_indicator_timeout) {
+        ev_timer_stop(main_loop, clear_indicator_timeout);
+        ev_timer_set(clear_indicator_timeout, 1.0, 0.);
+        ev_timer_start(main_loop, clear_indicator_timeout);
+    } else {
+        clear_indicator_timeout = calloc(sizeof(struct ev_timer), 1);
+        ev_timer_init(clear_indicator_timeout, clear_indicator, 1.0, 0.);
+        ev_timer_start(main_loop, clear_indicator_timeout);
+    }
+}
+
 static void input_done() {
     if (input_position == 0)
         return;
 
-    /* TODO: change cursor during authentication? */
+    if (clear_pam_wrong_timeout) {
+        ev_timer_stop(main_loop, clear_pam_wrong_timeout);
+        clear_pam_wrong_timeout = NULL;
+    }
+
+    pam_state = STATE_PAM_VERIFY;
+    redraw_screen();
+
     if (pam_authenticate(pam_handle, 0) == PAM_SUCCESS) {
         printf("successfully authenticated\n");
         exit(0);
@@ -107,6 +330,16 @@ static void input_done() {
 
     fprintf(stderr, "Authentication failure\n");
 
+    pam_state = STATE_PAM_WRONG;
+    redraw_screen();
+
+    /* Clear this state after 2 seconds (unless the user enters another
+     * password during that time). */
+    ev_now_update(main_loop);
+    clear_pam_wrong_timeout = calloc(sizeof(struct ev_timer), 1);
+    ev_timer_init(clear_pam_wrong_timeout, clear_pam_wrong, 2.0, 0.);
+    ev_timer_start(main_loop, clear_pam_wrong_timeout);
+
     /* beep on authentication failure, if enabled */
     if (beep) {
         xcb_bell(conn, 100);
@@ -138,6 +371,10 @@ static void handle_key_release(xcb_key_release_event_t *event) {
           modeswitch_active, iso_level3_shift_active);
 }
 
+static void redraw_timeout(EV_P_ ev_timer *w, int revents) {
+    redraw_screen();
+}
+
 /*
  * Handle key presses. Fixes state, then looks up the key symbol for the
  * given keycode, then looks up the key symbol (as UCS-2), converts it to
@@ -211,6 +448,13 @@ static void handle_key_press(xcb_key_press_event_t *event) {
         /* decrement input_position to point to the previous glyph */
         u8_dec(password, &input_position);
         password[input_position] = '\0';
+
+        /* Clear this state after 2 seconds (unless the user enters another
+         * password during that time). */
+        start_clear_indicator_timeout();
+        unlock_state = STATE_BACKSPACE_ACTIVE;
+        redraw_screen();
+        unlock_state = STATE_KEY_PRESSED;
         //printf("new input position = %d, new password = %s\n", input_position, password);
         return;
     }
@@ -260,6 +504,19 @@ static void handle_key_press(xcb_key_press_event_t *event) {
     input_position += convert_ucs_to_utf8((char*)inp, password + input_position);
     password[input_position] = '\0';
     DEBUG("current password = %s\n", password);
+
+    unlock_state = STATE_KEY_ACTIVE;
+    redraw_screen();
+    unlock_state = STATE_KEY_PRESSED;
+
+    struct ev_timer *timeout = calloc(sizeof(struct ev_timer), 1);
+    ev_timer_init(timeout, redraw_timeout, 0.25, 0.);
+    ev_timer_start(main_loop, timeout);
+
+    if (clear_indicator_timeout) {
+        ev_timer_stop(main_loop, clear_indicator_timeout);
+        clear_indicator_timeout = NULL;
+    }
 }
 
 /*
@@ -296,7 +553,7 @@ static void handle_mapping_notify(xcb_mapping_notify_event_t *event) {
  * and also redraw the image, if any.
  *
  */
-void handle_screen_resize(xcb_visualtype_t *vistype, xcb_window_t win, uint32_t* last_resolution, char* color) {
+void handle_screen_resize(xcb_visualtype_t *vistype, xcb_window_t win, uint32_t* last_resolution) {
     xcb_get_geometry_cookie_t geomc;
     xcb_get_geometry_reply_t *geom;
     geomc = xcb_get_geometry(conn, scr->root);
@@ -312,7 +569,7 @@ void handle_screen_resize(xcb_visualtype_t *vistype, xcb_window_t win, uint32_t*
 
 #ifndef NOLIBCAIRO
     if (img) {
-        xcb_pixmap_t bg_pixmap = draw_image(vistype, last_resolution, color);
+        xcb_pixmap_t bg_pixmap = draw_image(vistype, last_resolution);
         xcb_change_window_attributes(conn, win, XCB_CW_BACK_PIXMAP, (uint32_t[1]){ bg_pixmap });
     }
 #endif
@@ -354,10 +611,82 @@ static int conv_callback(int num_msg, const struct pam_message **msg,
     return 0;
 }
 
+/*
+ * 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) {
+            xcb_generic_error_t *error = (xcb_generic_error_t*)event;
+            fprintf(stderr, "X11 Error received! 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);
+
+        if (type == XCB_KEY_PRESS) {
+            handle_key_press((xcb_key_press_event_t*)event);
+            continue;
+        }
+
+        if (type == XCB_KEY_RELEASE) {
+            handle_key_release((xcb_key_release_event_t*)event);
+
+            /* If this was the backspace or escape key we are back at an
+             * empty input, so turn off the screen if DPMS is enabled */
+            if (dpms && input_position == 0)
+                dpms_turn_off_screen(conn);
+
+            continue;
+        }
+
+        if (type == XCB_VISIBILITY_NOTIFY) {
+            handle_visibility_notify((xcb_visibility_notify_event_t*)event);
+            continue;
+        }
+
+        if (type == XCB_MAPPING_NOTIFY) {
+            handle_mapping_notify((xcb_mapping_notify_event_t*)event);
+            continue;
+        }
+
+        if (type == XCB_CONFIGURE_NOTIFY) {
+            handle_screen_resize(vistype, win, last_resolution);
+            continue;
+        }
+
+        printf("WARNING: unhandled event of type %d\n", type);
+
+        free(event);
+    }
+}
+
 int main(int argc, char *argv[]) {
     bool dont_fork = false;
-    bool dpms = false;
-    char color[7] = "ffffff";
     char *username;
 #ifndef NOLIBCAIRO
     char *image_path = NULL;
@@ -365,9 +694,6 @@ int main(int argc, char *argv[]) {
     int ret;
     struct pam_conv conv = {conv_callback, NULL};
     int screen;
-    xcb_visualtype_t *vistype;
-    xcb_generic_event_t *event;
-    xcb_window_t win;
     int curs_choice = CURS_NONE;
     char o;
     int optind = 0;
@@ -380,6 +706,7 @@ int main(int argc, char *argv[]) {
         {"pointer", required_argument, NULL , 'p'},
         {"debug", no_argument, NULL, 0},
         {"help", no_argument, NULL, 'h'},
+        {"no-unlock-indicator", no_argument, NULL, 'u'},
 #ifndef NOLIBCAIRO
         {"image", required_argument, NULL, 'i'},
         {"tiling", no_argument, NULL, 't'},
@@ -390,7 +717,7 @@ int main(int argc, char *argv[]) {
     if ((username = getenv("USER")) == NULL)
         errx(1, "USER environment variable not set, please set it.\n");
 
-    while ((o = getopt_long(argc, argv, "hvnbdc:p:"
+    while ((o = getopt_long(argc, argv, "hvnbdc:p:u"
 #ifndef NOLIBCAIRO
         "i:t"
 #endif
@@ -419,6 +746,9 @@ int main(int argc, char *argv[]) {
 
             break;
         }
+        case 'u':
+            unlock_indicator = false;
+            break;
 #ifndef NOLIBCAIRO
         case 'i':
             image_path = strdup(optarg);
@@ -441,7 +771,7 @@ int main(int argc, char *argv[]) {
                 debug_mode = true;
             break;
         default:
-            errx(1, "Syntax: i3lock [-v] [-n] [-b] [-d] [-c color] [-p win|default]"
+            errx(1, "Syntax: i3lock [-v] [-n] [-b] [-d] [-c color] [-u] [-p win|default]"
 #ifndef NOLIBCAIRO
             " [-i image.png] [-t]"
 #else
@@ -451,6 +781,10 @@ int main(int argc, char *argv[]) {
         }
     }
 
+    /* We need (relatively) random numbers for highlighting a random part of
+     * the unlock indicator upon keypresses. */
+    srand(time(NULL));
+
     /* Initialize PAM */
     ret = pam_start("i3lock", username, &conv, &pam_handle);
     if (ret != PAM_SUCCESS)
@@ -480,8 +814,8 @@ int main(int argc, char *argv[]) {
     scr = xcb_setup_roots_iterator(xcb_get_setup(conn)).data;
     vistype = get_root_visual_type(scr);
 
-    uint32_t last_resolution[2] = {scr->width_in_pixels, scr->height_in_pixels};
-
+    last_resolution[0] = scr->width_in_pixels;
+    last_resolution[1] = scr->height_in_pixels;
 
 
 #ifndef NOLIBCAIRO
@@ -492,7 +826,7 @@ int main(int argc, char *argv[]) {
 #endif
 
     /* Pixmap on which the image is rendered to (if any) */
-    xcb_pixmap_t bg_pixmap = draw_image(vistype, last_resolution, color);
+    xcb_pixmap_t bg_pixmap = draw_image(vistype, last_resolution);
 
     /* open the fullscreen window, already with the correct pixmap in place */
     win = open_fullscreen_window(conn, scr, color, bg_pixmap);
@@ -508,46 +842,24 @@ int main(int argc, char *argv[]) {
     if (dpms)
         dpms_turn_off_screen(conn);
 
-    while ((event = xcb_wait_for_event(conn))) {
-        if (event->response_type == 0)
-            errx(1, "XCB: Invalid event received");
-
-        /* Strip off the highest bit (set if the event is generated) */
-        int type = (event->response_type & 0x7F);
-
-        if (type == XCB_KEY_PRESS) {
-            handle_key_press((xcb_key_press_event_t*)event);
-            continue;
-        }
-
-        if (type == XCB_KEY_RELEASE) {
-            handle_key_release((xcb_key_release_event_t*)event);
-
-            /* If this was the backspace or escape key we are back at an
-             * empty input, so turn off the screen if DPMS is enabled */
-            if (dpms && input_position == 0)
-                dpms_turn_off_screen(conn);
-
-            continue;
-        }
+    /* Initialize the libev event loop. */
+    main_loop = EV_DEFAULT;
+    if (main_loop == NULL)
+        errx(EXIT_FAILURE, "Could not initialize libev. Bad LIBEV_FLAGS?\n");
 
-        if (type == XCB_VISIBILITY_NOTIFY) {
-            handle_visibility_notify((xcb_visibility_notify_event_t*)event);
-            continue;
-        }
+    struct ev_io *xcb_watcher = calloc(sizeof(struct ev_io), 1);
+    struct ev_check *xcb_check = calloc(sizeof(struct ev_check), 1);
+    struct ev_prepare *xcb_prepare = calloc(sizeof(struct ev_prepare), 1);
 
-        if (type == XCB_MAPPING_NOTIFY) {
-            handle_mapping_notify((xcb_mapping_notify_event_t*)event);
-            continue;
-        }
+    ev_io_init(xcb_watcher, xcb_got_event, xcb_get_file_descriptor(conn), EV_READ);
+    ev_io_start(main_loop, xcb_watcher);
 
-        if (type == XCB_CONFIGURE_NOTIFY) {
-            handle_screen_resize(vistype, win, last_resolution, color);
-            continue;
-        }
+    ev_check_init(xcb_check, xcb_check_cb);
+    ev_check_start(main_loop, xcb_check);
 
-        printf("WARNING: unhandled event of type %d\n", type);
-    }
+    ev_prepare_init(xcb_prepare, xcb_prepare_cb);
+    ev_prepare_start(main_loop, xcb_prepare);
 
-    return 0;
+    xcb_flush(conn);
+    ev_loop(main_loop, 0);
 }