implemented logging the number of failed attempts

This closes #1243

i3lock.1

@@ -29,6 +29,7 @@ i3lock \- improved screen locker
 .RB [\|\-u\|]
 .RB [\|\-e\|]
 .RB [\|\-I\|]
+.RB [\|\-f\|]
 
 .SH DESCRIPTION
 .B i3lock
@@ -115,6 +116,10 @@ another try. This can be useful if the XF86ScreenSaver key is used to
 put a laptop to sleep and bounce on resume or if you happen to wake up
 your computer with the enter key.
 
+.TP
+.B \-f, \-\-show-failed-attempts
+Show the number of failed attempts, if any.
+
 .SH SEE ALSO
 .IR xautolock(1)
 \- use i3lock as your screen saver

i3lock.c

@@ -64,6 +64,8 @@ static struct ev_timer *dpms_timeout;
 static struct ev_timer *discard_passwd_timeout;
 extern unlock_state_t unlock_state;
 extern pam_state_t pam_state;
+int failed_attempts = 0;
+bool show_failed_attempts = false;
 
 static struct xkb_state *xkb_state;
 static struct xkb_context *xkb_context;
@@ -239,6 +241,7 @@ static void input_done(void) {
         fprintf(stderr, "Authentication failure\n");
 
     pam_state = STATE_PAM_WRONG;
+    failed_attempts += 1;
     clear_input();
     redraw_screen();
 
@@ -674,13 +677,14 @@ int main(int argc, char *argv[]) {
         {"tiling", no_argument, NULL, 't'},
         {"ignore-empty-password", no_argument, NULL, 'e'},
         {"inactivity-timeout", required_argument, NULL, 'I'},
+        {"show-failed-attempts", no_argument, NULL, 'f'},
         {NULL, no_argument, NULL, 0}
     };
 
     if ((username = getenv("USER")) == NULL)
         errx(EXIT_FAILURE, "USER environment variable not set, please set it.\n");
 
-    char *optstring = "hvnbdc:p:ui:teI:";
+    char *optstring = "hvnbdc:p:ui:teI:f";
     while ((o = getopt_long(argc, argv, optstring, longopts, &optind)) != -1) {
         switch (o) {
         case 'v':
@@ -738,9 +742,12 @@ int main(int argc, char *argv[]) {
             if (strcmp(longopts[optind].name, "debug") == 0)
                 debug_mode = true;
             break;
+        case 'f':
+            show_failed_attempts = true;
+            break;
         default:
             errx(EXIT_FAILURE, "Syntax: i3lock [-v] [-n] [-b] [-d] [-c color] [-u] [-p win|default]"
-            " [-i image.png] [-t] [-e] [-I]"
+            " [-i image.png] [-t] [-e] [-I] [-f]"
             );
         }
     }

unlock_indicator.c

@@ -52,6 +52,11 @@ extern bool tile;
 /* The background color to use (in hex). */
 extern char color[7];
 
+/* Whether the failed attempts should be displayed. */
+extern bool show_failed_attempts;
+/* Number of failed unlock attempts. */
+extern int failed_attempts;
+
 /*******************************************************************************
  * Variables defined in xcb.c.
  ******************************************************************************/
@@ -185,6 +190,11 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
 
         /* Display a (centered) text of the current PAM state. */
         char *text = NULL;
+        /* We don't want to show more than a 3-digit number. */
+        char buf[4];
+
+        cairo_set_source_rgb(ctx, 0, 0, 0);
+        cairo_set_font_size(ctx, 28.0);
         switch (pam_state) {
             case STATE_PAM_VERIFY:
                 text = "verifying…";
@@ -193,16 +203,23 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
                 text = "wrong!";
                 break;
             default:
+                if (show_failed_attempts && failed_attempts > 0){
+                    if (failed_attempts > 999) {
+                        text = "> 999";
+                    } else {
+                        snprintf(buf, sizeof(buf), "%d", failed_attempts);
+                        text = buf;
+                    }
+                    cairo_set_source_rgb(ctx, 1, 0, 0);
+                    cairo_set_font_size(ctx, 32.0);
+                }
                 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 = BUTTON_CENTER - ((extents.width / 2) + extents.x_bearing);
             y = BUTTON_CENTER - ((extents.height / 2) + extents.y_bearing);