Avoid TTY cursor blinking

Fixes: #26

main.c

@@ -23,6 +23,7 @@
 #include "indev.h"
 #include "log.h"
 #include "unl0kr.h"
+#include "terminal.h"
 #include "theme.h"
 #include "themes.h"
 
@@ -32,6 +33,7 @@
 
 #include "squeek2lvgl/sq2lv.h"
 
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -170,7 +172,14 @@ static void textarea_ready_cb(lv_event_t *event);
  *
  * @param textarea the textarea widget
  */
-static void finish(lv_obj_t *textarea);
+static void print_password_and_exit(lv_obj_t *textarea);
+
+/**
+ * Handle termination signals sent to the process.
+ *
+ * @param signum the signal's number
+ */
+static void sigaction_handler(int signum);
 
 
 /**
@@ -280,15 +289,20 @@ static void keyboard_value_changed_cb(lv_event_t *event) {
 }
 
 static void keyboard_ready_cb(lv_event_t *event) {
-    finish(lv_keyboard_get_textarea(lv_event_get_target(event)));
+    print_password_and_exit(lv_keyboard_get_textarea(lv_event_get_target(event)));
 }
 
 static void textarea_ready_cb(lv_event_t *event) {
-    finish(lv_event_get_target(event));
+    print_password_and_exit(lv_event_get_target(event));
 }
 
-static void finish(lv_obj_t *textarea) {
+static void print_password_and_exit(lv_obj_t *textarea) {
     printf("%s\n", lv_textarea_get_text(textarea));
+    sigaction_handler(SIGTERM);
+}
+
+static void sigaction_handler(int signum) {
+    ul_terminal_reset_current_terminal();
     exit(0);
 }
 
@@ -312,6 +326,14 @@ int main(int argc, char *argv[]) {
     /* Parse config files */
     ul_config_parse(cli_opts.config_files, cli_opts.num_config_files, &conf_opts);
 
+    /* Prepare current TTY and clean up on termination */
+    ul_terminal_prepare_current_terminal();
+    struct sigaction action;
+    memset(&action, 0, sizeof(action));
+    action.sa_handler = sigaction_handler;
+    sigaction(SIGINT, &action, NULL);
+    sigaction(SIGTERM, &action, NULL);
+
     /* Initialise LVGL and set up logging callback */
     lv_init();
     lv_log_register_print_cb(ul_log_print_cb);

meson.build

@@ -35,6 +35,7 @@ unl0kr_sources = [
   'log.c',
   'main.c',
   'sq2lv_layouts.c',
+  'terminal.c',
   'theme.c',
   'themes.c'
 ]

terminal.c

@@ -0,0 +1,100 @@
+/**
+ * Copyright 2021 Johannes Marbach
+ *
+ * This file is part of unl0kr, hereafter referred to as the program.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#include "terminal.h"
+
+#include "log.h"
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <unistd.h>
+
+#include <linux/kd.h>
+
+#include <sys/ioctl.h>
+
+
+/**
+ * Static variables
+ */
+
+static int current_fd = -1;
+
+
+/**
+ * Static prototypes
+ */
+
+/**
+ * Close the current file descriptor and reopen /dev/tty0.
+ * 
+ * @return true if opening was successful, false otherwise
+ */
+static bool reopen_current_terminal(void);
+
+/**
+ * Close the current file descriptor.
+ */
+static void close_current_terminal(void);
+
+
+/**
+ * Static functions
+ */
+
+static bool reopen_current_terminal(void) {
+    close_current_terminal();
+
+    current_fd = open("/dev/tty0", O_RDWR);
+	if (current_fd < 0) {
+        ul_log(UL_LOG_LEVEL_WARNING, "Could not open /dev/tty0");
+		return false;
+	}
+
+    return true;
+}
+
+static void close_current_terminal(void) {
+    if (current_fd < 0) {
+        return;
+    }
+
+    close(current_fd);
+    current_fd = -1;
+}
+
+
+/**
+ * Public functions
+ */
+
+void ul_terminal_prepare_current_terminal(void) {
+    reopen_current_terminal();
+    if (current_fd < 0 || ioctl(current_fd, KDSETMODE, KD_GRAPHICS) != 0) {
+        ul_log(UL_LOG_LEVEL_WARNING, "Could not set current terminal to graphics mode");
+    }
+}
+
+void ul_terminal_reset_current_terminal(void) {
+    if (current_fd < 0 || ioctl(current_fd, KDSETMODE, KD_TEXT) != 0) {
+        ul_log(UL_LOG_LEVEL_WARNING, "Could not reset current terminal to text mode");
+    }
+    close_current_terminal();
+}

terminal.h

@@ -0,0 +1,34 @@
+/**
+ * Copyright 2021 Johannes Marbach
+ *
+ * This file is part of unl0kr, hereafter referred to as the program.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+
+#ifndef UL_TERMINAL_H
+#define UL_TERMINAL_H
+
+/**
+ * Prepare the current TTY for graphics output.
+ */
+void ul_terminal_prepare_current_terminal(void);
+
+/**
+ * Reset the current TTY to text output.
+ */
+void ul_terminal_reset_current_terminal(void);
+
+#endif /* UL_TERMINAL_H */