recovery_ui/ui.cpp - LeafOS-Project/android_bootable_recovery - Gitiles

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "recovery_ui/ui.h"

 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <time.h>
 #include <unistd.h>

 #include <chrono>
 #include <functional>
 #include <string>
 #include <thread>

 #include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <volume_manager/VolumeManager.h>

 #include "minui/minui.h"
 #include "otautil/sysutil.h"

 using namespace std::chrono_literals;

 constexpr int UI_WAIT_KEY_TIMEOUT_SEC = 120;
 constexpr const char* DEFAULT_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/brightness";
 constexpr const char* DEFAULT_MAX_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/max_brightness";
 constexpr const char* BRIGHTNESS_FILE_SDM = "/sys/class/backlight/panel0-backlight/brightness";
 constexpr const char* MAX_BRIGHTNESS_FILE_SDM =
     "/sys/class/backlight/panel0-backlight/max_brightness";
 constexpr const char* BRIGHTNESS_FILE_PWM = "/sys/class/backlight/pwm-backlight.0/brightness";
 constexpr const char* MAX_BRIGHTNESS_FILE_PWM =
     "/sys/class/backlight/pwm-backlight.0/max_brightness";

 constexpr int kDefaultTouchLowThreshold = 50;
 constexpr int kDefaultTouchHighThreshold = 90;

 constexpr int kDefaultNormalBrightnessPercent = 50;
 constexpr int kDefaultDimmedBrightnessPercent = 25;

 RecoveryUI::RecoveryUI()
     : brightness_normal_(android::base::GetIntProperty("ro.recovery.ui.brightness_normal_percent",
                                                        kDefaultNormalBrightnessPercent)),
       brightness_dimmed_(android::base::GetIntProperty("ro.recovery.ui.brightness_dimmed_percent",
                                                        kDefaultDimmedBrightnessPercent)),
       brightness_file_(
           android::base::GetProperty("ro.recovery.ui.brightness_file", DEFAULT_BRIGHTNESS_FILE)),
       max_brightness_file_(android::base::GetProperty("ro.recovery.ui.max_brightness_file",
                                                       DEFAULT_MAX_BRIGHTNESS_FILE)),
       touch_screen_allowed_(true),
       fastbootd_logo_enabled_(false),
       sideload_auto_reboot_(false),
       touch_low_threshold_(android::base::GetIntProperty("ro.recovery.ui.touch_low_threshold",
                                                          kDefaultTouchLowThreshold)),
       touch_high_threshold_(android::base::GetIntProperty("ro.recovery.ui.touch_high_threshold",
                                                           kDefaultTouchHighThreshold)),
       key_interrupted_(false),
       event_queue_len(0),
       key_last_down(-1),
       key_long_press(false),
       key_down_count(0),
       enable_reboot(true),
       consecutive_power_keys(0),
       has_power_key(false),
       has_up_key(false),
       has_down_key(false),
       has_touch_screen(false),
       touch_slot_(0),
       touch_finger_down_(false),
       touch_saw_x_(false),
       touch_saw_y_(false),
       touch_reported_(false),
       is_bootreason_recovery_ui_(false),
       screensaver_state_(ScreensaverState::DISABLED) {
   memset(key_pressed, 0, sizeof(key_pressed));
 }

 RecoveryUI::~RecoveryUI() {
   ev_exit();
   input_thread_stopped_ = true;
   if (input_thread_.joinable()) {
     input_thread_.join();
   }
 }

 void RecoveryUI::OnTouchDeviceDetected(int fd) {
   char name[256];
   char path[PATH_MAX];
   char buf[4096];

   memset(name, 0, sizeof(name));
   if (ioctl(fd, EVIOCGNAME(sizeof(name)), name) < 0) {
     return;
   }
   sprintf(path, "/sys/board_properties/virtualkeys.%s", name);
   int vkfd = open(path, O_RDONLY);
   if (vkfd < 0) {
     LOG(INFO) << "vkeys: could not open " << path;
     return;
   }
   ssize_t len = read(vkfd, buf, sizeof(buf));
   close(vkfd);
   if (len <= 0) {
     LOG(ERROR) << "vkeys: could not read " << path;
     return;
   }
   buf[len] = '\0';

   char* p = buf;
   char* endp;
   for (size_t n = 0; p < buf + len && *p == '0'; ++n) {
     int val[6];
     int f;
     for (f = 0; *p && f < 6; ++f) {
       val[f] = strtol(p, &endp, 0);
       if (p == endp) break;
       p = endp + 1;
     }
     if (f != 6 || val[0] != 0x01) break;
     vkey_t vk;
     vk.keycode = val[1];
     vk.min_ = Point(val[2] - val[4] / 2, val[3] - val[5] / 2);
     vk.max_ = Point(val[2] + val[4] / 2, val[3] + val[5] / 2);
     virtual_keys_.push_back(vk);
   }
 }

 void RecoveryUI::OnKeyDetected(int key_code) {
   if (key_code == KEY_POWER) {
     has_power_key = true;
   } else if (key_code == KEY_DOWN || key_code == KEY_VOLUMEDOWN) {
     has_down_key = true;
   } else if (key_code == KEY_UP || key_code == KEY_VOLUMEUP) {
     has_up_key = true;
   } else if (key_code == ABS_MT_POSITION_X || key_code == ABS_MT_POSITION_Y) {
     has_touch_screen = true;
   }
 }

 bool RecoveryUI::InitScreensaver() {
   // Disabled.
   if (brightness_normal_ == 0 || brightness_dimmed_ > brightness_normal_) {
     return false;
   }
   if (access(brightness_file_.c_str(), R_OK | W_OK)) {
     if (!access(BRIGHTNESS_FILE_SDM, R_OK | W_OK)) {
       brightness_file_ = BRIGHTNESS_FILE_SDM;
     } else {
       brightness_file_ = BRIGHTNESS_FILE_PWM;
     }
   }

   if (access(max_brightness_file_.c_str(), R_OK)) {
     if (!access(MAX_BRIGHTNESS_FILE_SDM, R_OK)) {
       max_brightness_file_ = MAX_BRIGHTNESS_FILE_SDM;
     } else {
       max_brightness_file_ = MAX_BRIGHTNESS_FILE_PWM;
     }
   }
   // Set the initial brightness level based on the max brightness. Note that reading the initial
   // value from BRIGHTNESS_FILE doesn't give the actual brightness value (bullhead, sailfish), so
   // we don't have a good way to query the default value.
   std::string content;
   if (!android::base::ReadFileToString(max_brightness_file_, &content)) {
     PLOG(WARNING) << "Failed to read max brightness";
     return false;
   }

   unsigned int max_value;
   if (!android::base::ParseUint(android::base::Trim(content), &max_value)) {
     LOG(WARNING) << "Failed to parse max brightness: " << content;
     return false;
   }

   brightness_normal_value_ = max_value * brightness_normal_ / 100.0;
   brightness_dimmed_value_ = max_value * brightness_dimmed_ / 100.0;
   if (!android::base::WriteStringToFile(std::to_string(brightness_normal_value_),
                                         brightness_file_)) {
     PLOG(WARNING) << "Failed to set brightness";
     return false;
   }

   LOG(INFO) << "Brightness: " << brightness_normal_value_ << " (" << brightness_normal_ << "%)";
   screensaver_state_ = ScreensaverState::NORMAL;
   return true;
 }

 bool RecoveryUI::Init(const std::string& /* locale */) {
   ev_init(std::bind(&RecoveryUI::OnInputEvent, this, std::placeholders::_1, std::placeholders::_2),
           touch_screen_allowed_);

   ev_iterate_available_keys(std::bind(&RecoveryUI::OnKeyDetected, this, std::placeholders::_1));

   if (touch_screen_allowed_) {
     ev_iterate_touch_inputs(
         std::bind(&RecoveryUI::OnTouchDeviceDetected, this, std::placeholders::_1),
         std::bind(&RecoveryUI::OnKeyDetected, this, std::placeholders::_1));

     // Parse /proc/cmdline to determine if it's booting into recovery with a bootreason of
     // "recovery_ui". This specific reason is set by some (wear) bootloaders, to allow an easier way
     // to turn on text mode. It will only be set if the recovery boot is triggered from fastboot, or
     // with 'adb reboot recovery'. Note that this applies to all build variants. Otherwise the text
     // mode will be turned on automatically on debuggable builds, even without a swipe.
     std::string cmdline;
     if (android::base::ReadFileToString("/proc/cmdline", &cmdline)) {
       is_bootreason_recovery_ui_ = cmdline.find("bootreason=recovery_ui") != std::string::npos;
     } else {
       // Non-fatal, and won't affect Init() result.
       PLOG(WARNING) << "Failed to read /proc/cmdline";
     }
   }

   if (!InitScreensaver()) {
     LOG(INFO) << "Screensaver disabled";
   }

   // Create a separate thread that handles input events.
   input_thread_ = std::thread([this]() {
     while (!this->input_thread_stopped_) {
       if (!ev_wait(500)) {
         ev_dispatch();
       }
     }
   });

   return true;
 }

 void RecoveryUI::CalibrateTouch(int fd) {
   struct input_absinfo info;
   static bool calibrated = false;

   if (calibrated) return;

   memset(&info, 0, sizeof(info));
   if (ioctl(fd, EVIOCGABS(ABS_MT_POSITION_X), &info) == 0) {
     touch_min_.x(info.minimum);
     touch_max_.x(info.maximum);
   }
   memset(&info, 0, sizeof(info));
   if (ioctl(fd, EVIOCGABS(ABS_MT_POSITION_Y), &info) == 0) {
     touch_min_.y(info.minimum);
     touch_max_.y(info.maximum);
   }

   calibrated = true;
 }

 void RecoveryUI::OnTouchPress() {
   touch_start_ = touch_track_ = touch_pos_;
 }

 void RecoveryUI::OnTouchTrack() {
   if (touch_pos_.y() <= gr_fb_height_real()) {
     while (abs(touch_pos_.y() - touch_track_.y()) >= MenuItemHeight()) {
       int dy = touch_pos_.y() - touch_track_.y();
       int key = (dy < 0) ? KEY_SCROLLDOWN : KEY_SCROLLUP;
       ProcessKey(key, 1);  // press key
       ProcessKey(key, 0);  // and release it
       int sgn = (dy > 0) - (dy < 0);
       touch_track_.y(touch_track_.y() + sgn * MenuItemHeight());
     }
   }
 }

 void RecoveryUI::OnTouchRelease() {
   // Allow turning on text mode with any swipe, if bootloader has set a bootreason of recovery_ui.
   if (is_bootreason_recovery_ui_ && !IsTextVisible()) {
     ShowText(true);
     return;
   }

   // Check vkeys.  Only report if touch both starts and ends in the vkey.
   if (touch_start_.y() > gr_fb_height_real() && touch_pos_.y() > gr_fb_height_real()) {
     for (const auto& vk : virtual_keys_) {
       if (vk.inside(touch_start_) && vk.inside(touch_pos_)) {
         ProcessKey(vk.keycode, 1);  // press key
         ProcessKey(vk.keycode, 0);  // and release it
       }
     }
     return;
   }

   // If we tracked a vertical swipe, ignore the release
   if (touch_track_ != touch_start_) {
     return;
   }

   // Simple touch
   EnqueueTouch(touch_pos_);
 }

 int RecoveryUI::OnInputEvent(int fd, uint32_t epevents) {
   struct input_event ev;
   if (ev_get_input(fd, epevents, &ev) == -1) {
     return -1;
   }

   // Touch inputs handling.
   //
   // Per the doc Multi-touch Protocol at below, there are two protocols.
   // https://www.kernel.org/doc/Documentation/input/multi-touch-protocol.txt
   //
   // The main difference between the stateless type A protocol and the stateful type B slot protocol
   // lies in the usage of identifiable contacts to reduce the amount of data sent to userspace. The
   // slot protocol (i.e. type B) sends ABS_MT_TRACKING_ID with a unique id on initial contact, and
   // sends ABS_MT_TRACKING_ID -1 upon lifting the contact. Protocol A doesn't send
   // ABS_MT_TRACKING_ID -1 on lifting, but the driver may additionally report BTN_TOUCH event.
   //
   // For protocol A, we rely on BTN_TOUCH to recognize lifting, while for protocol B we look for
   // ABS_MT_TRACKING_ID being -1.
   //
   // Touch input events will only be available if touch_screen_allowed_ is set.

   if (ev.type == EV_SYN) {
     if (touch_screen_allowed_ && ev.code == SYN_REPORT) {
       // There might be multiple SYN_REPORT events. Only report press/release once.
       if (!touch_reported_ && touch_finger_down_) {
         if (touch_saw_x_ && touch_saw_y_) {
           OnTouchPress();
           touch_reported_ = true;
           touch_saw_x_ = touch_saw_y_ = false;
         }
       } else if (touch_reported_ && !touch_finger_down_) {
         OnTouchRelease();
         touch_reported_ = false;
         touch_saw_x_ = touch_saw_y_ = false;
       }
     }
     return 0;
   }

   if (ev.type == EV_REL) {
     if (ev.code == REL_Y) {
       // accumulate the up or down motion reported by
       // the trackball.  When it exceeds a threshold
       // (positive or negative), fake an up/down
       // key event.
       rel_sum += ev.value;
       if (rel_sum > 3) {
         ProcessKey(KEY_DOWN, 1);  // press down key
         ProcessKey(KEY_DOWN, 0);  // and release it
         rel_sum = 0;
       } else if (rel_sum < -3) {
         ProcessKey(KEY_UP, 1);  // press up key
         ProcessKey(KEY_UP, 0);  // and release it
         rel_sum = 0;
       }
     }
   } else {
     rel_sum = 0;
   }

   if (touch_screen_allowed_ && ev.type == EV_ABS) {
     CalibrateTouch(fd);
     if (ev.code == ABS_MT_SLOT) {
       touch_slot_ = ev.value;
     }
     // Ignore other fingers.
     if (touch_slot_ > 0) return 0;

     switch (ev.code) {
       case ABS_MT_POSITION_X:
         touch_finger_down_ = true;
         touch_saw_x_ = true;
         touch_pos_.x(ev.value * gr_fb_width_real() / (touch_max_.x() - touch_min_.x()));
         if (touch_reported_ && touch_saw_y_) {
           OnTouchTrack();
           touch_saw_x_ = touch_saw_y_ = false;
         }
         break;

       case ABS_MT_POSITION_Y:
         touch_finger_down_ = true;
         touch_saw_y_ = true;
         touch_pos_.y(ev.value * gr_fb_height_real() / (touch_max_.y() - touch_min_.y()));
         if (touch_reported_ && touch_saw_x_) {
           OnTouchTrack();
           touch_saw_x_ = touch_saw_y_ = false;
         }
         break;

       case ABS_MT_TRACKING_ID:
         // Protocol B: -1 marks lifting the contact.
         if (ev.value < 0) touch_finger_down_ = false;
         break;
     }
     return 0;
   }

   if (ev.type == EV_KEY && ev.code <= KEY_MAX) {
     if (touch_screen_allowed_) {
       if (ev.code == BTN_TOUCH) {
         // A BTN_TOUCH with value 1 indicates the start of contact (protocol A), with 0 means
         // lifting the contact.
         touch_finger_down_ = (ev.value == 1);
       }

       // Intentionally ignore BTN_TOUCH and BTN_TOOL_FINGER, which would otherwise trigger
       // additional scrolling (because in ScreenRecoveryUI::ShowFile(), we consider keys other than
       // KEY_POWER and KEY_UP as KEY_DOWN).
       if (ev.code == BTN_TOUCH || ev.code == BTN_TOOL_FINGER) {
         return 0;
       }
     }

     ProcessKey(ev.code, ev.value);
   }

   // For Lid switch handle
   if (ev.type == EV_SW) {
     SetSwCallback(ev.code, ev.value);
   }

   return 0;
 }

 // Processes a key-up or -down event. A key is "registered" when it is pressed and then released,
 // with no other keypresses or releases in between. Registered keys are passed to CheckKey() to
 // see if it should trigger a visibility toggle, an immediate reboot, or be queued to be processed
 // next time the foreground thread wants a key (eg, for the menu).
 //
 // We also keep track of which keys are currently down so that CheckKey() can call IsKeyPressed()
 // to see what other keys are held when a key is registered.
 //
 // updown == 1 for key down events; 0 for key up events
 void RecoveryUI::ProcessKey(int key_code, int updown) {
   bool register_key = false;
   bool long_press = false;

   {
     std::lock_guard<std::mutex> lg(key_press_mutex);
     key_pressed[key_code] = updown;
     if (updown) {
       ++key_down_count;
       key_last_down = key_code;
       key_long_press = false;
       std::thread time_key_thread(&RecoveryUI::TimeKey, this, key_code, key_down_count);
       time_key_thread.detach();
     } else {
       if (key_last_down == key_code) {
         long_press = key_long_press;
         register_key = true;
       }
       key_last_down = -1;
     }
   }

   bool reboot_enabled = enable_reboot;
   if (register_key) {
     switch (CheckKey(key_code, long_press)) {
       case RecoveryUI::IGNORE:
         break;

       case RecoveryUI::TOGGLE:
         ShowText(!IsTextVisible());
         break;

       case RecoveryUI::REBOOT:
         if (reboot_enabled) {
           android::volmgr::VolumeManager::Instance()->unmountAll();
           Reboot("userrequested,recovery,ui");
         }
         break;

       case RecoveryUI::ENQUEUE:
         EnqueueKey(key_code);
         break;
     }
   }
 }

 void RecoveryUI::TimeKey(int key_code, int count) {
   std::this_thread::sleep_for(750ms);  // 750 ms == "long"
   bool long_press = false;
   {
     std::lock_guard<std::mutex> lg(key_press_mutex);
     if (key_last_down == key_code && key_down_count == count) {
       long_press = key_long_press = true;
     }
   }
   if (long_press) KeyLongPress(key_code);
 }

 void RecoveryUI::EnqueueKey(int key_code) {
   std::lock_guard<std::mutex> lg(event_queue_mutex);
   const int queue_max = sizeof(event_queue) / sizeof(event_queue[0]);
   if (event_queue_len < queue_max) {
     InputEvent event(key_code);
     event_queue[event_queue_len++] = event;
     event_queue_cond.notify_one();
   }
 }

 void RecoveryUI::EnqueueTouch(const Point& pos) {
   std::lock_guard<std::mutex> lg(event_queue_mutex);
   const int queue_max = sizeof(event_queue) / sizeof(event_queue[0]);
   if (event_queue_len < queue_max) {
     InputEvent event(pos);
     event_queue[event_queue_len++] = event;
     event_queue_cond.notify_one();
   }
 }

 void RecoveryUI::SetScreensaverState(ScreensaverState state) {
   switch (state) {
     case ScreensaverState::NORMAL:
       if (android::base::WriteStringToFile(std::to_string(brightness_normal_value_),
                                            brightness_file_)) {
         screensaver_state_ = ScreensaverState::NORMAL;
         LOG(INFO) << "Brightness: " << brightness_normal_value_ << " (" << brightness_normal_
                   << "%)";
       } else {
         LOG(WARNING) << "Unable to set brightness to normal";
       }
       break;
     case ScreensaverState::DIMMED:
       if (android::base::WriteStringToFile(std::to_string(brightness_dimmed_value_),
                                            brightness_file_)) {
         LOG(INFO) << "Brightness: " << brightness_dimmed_value_ << " (" << brightness_dimmed_
                   << "%)";
         screensaver_state_ = ScreensaverState::DIMMED;
       } else {
         LOG(WARNING) << "Unable to set brightness to dim";
       }
       break;
     case ScreensaverState::OFF:
       if (android::base::WriteStringToFile("0", brightness_file_)) {
         LOG(INFO) << "Brightness: 0 (off)";
         screensaver_state_ = ScreensaverState::OFF;
       } else {
         LOG(WARNING) << "Unable to set brightness to off";
       }
       break;
     default:
       LOG(ERROR) << "Invalid screensaver state";
   }
 }

 RecoveryUI::InputEvent RecoveryUI::WaitInputEvent() {
   std::unique_lock<std::mutex> lk(event_queue_mutex);

   // Check for a saved key queue interruption.
   if (key_interrupted_) {
     SetScreensaverState(ScreensaverState::NORMAL);
     return InputEvent(EventType::EXTRA, KeyError::INTERRUPTED);
   }

   // Time out after UI_WAIT_KEY_TIMEOUT_SEC, unless a USB cable is plugged in.
   do {
     bool rc = event_queue_cond.wait_for(lk, std::chrono::seconds(UI_WAIT_KEY_TIMEOUT_SEC), [this] {
       return this->event_queue_len != 0 || key_interrupted_;
     });
     if (key_interrupted_) {
       SetScreensaverState(ScreensaverState::NORMAL);
       return InputEvent(EventType::EXTRA, KeyError::INTERRUPTED);
     }
     if (screensaver_state_ != ScreensaverState::DISABLED) {
       if (!rc) {
         // Must be after a timeout. Lower the brightness level: NORMAL -> DIMMED; DIMMED -> OFF.
         if (screensaver_state_ == ScreensaverState::NORMAL) {
           SetScreensaverState(ScreensaverState::DIMMED);
         } else if (screensaver_state_ == ScreensaverState::DIMMED) {
           SetScreensaverState(ScreensaverState::OFF);
         }
       } else if (screensaver_state_ != ScreensaverState::NORMAL) {
         // Drop the first key if it's changing from OFF to NORMAL.
         if (screensaver_state_ == ScreensaverState::OFF) {
           if (event_queue_len > 0) {
             memcpy(&event_queue[0], &event_queue[1], sizeof(int) * --event_queue_len);
           }
         }

         // Reset the brightness to normal.
         SetScreensaverState(ScreensaverState::NORMAL);
       }
     }
   } while (IsUsbConnected() && event_queue_len == 0);

   InputEvent event;
   if (event_queue_len > 0) {
     event = event_queue[0];
     memcpy(&event_queue[0], &event_queue[1], sizeof(InputEvent) * --event_queue_len);
   }
   return event;
 }

 void RecoveryUI::CancelWaitKey() {
   EnqueueKey(KEY_AGAIN);
 }

 void RecoveryUI::InterruptKey() {
   {
     std::lock_guard<std::mutex> lg(event_queue_mutex);
     key_interrupted_ = true;
   }
   event_queue_cond.notify_one();
 }

 bool RecoveryUI::IsUsbConnected() {
   int fd = open("/sys/class/android_usb/android0/state", O_RDONLY);
   if (fd < 0) {
     printf("failed to open /sys/class/android_usb/android0/state: %s\n", strerror(errno));
     return 0;
   }

   char buf;
   // USB is connected if android_usb state is CONNECTED or CONFIGURED.
   int connected = (TEMP_FAILURE_RETRY(read(fd, &buf, 1)) == 1) && (buf == 'C');
   if (close(fd) < 0) {
     printf("failed to close /sys/class/android_usb/android0/state: %s\n", strerror(errno));
   }
   return connected;
 }

 bool RecoveryUI::IsKeyPressed(int key) {
   std::lock_guard<std::mutex> lg(key_press_mutex);
   int pressed = key_pressed[key];
   return pressed;
 }

 bool RecoveryUI::IsLongPress() {
   std::lock_guard<std::mutex> lg(key_press_mutex);
   bool result = key_long_press;
   return result;
 }

 bool RecoveryUI::HasThreeButtons() const {
   return has_power_key && has_up_key && has_down_key;
 }

 bool RecoveryUI::HasPowerKey() const {
   return has_power_key;
 }

 bool RecoveryUI::HasTouchScreen() const {
   return has_touch_screen;
 }

 void RecoveryUI::FlushKeys() {
   std::lock_guard<std::mutex> lg(event_queue_mutex);
   event_queue_len = 0;
 }

 RecoveryUI::KeyAction RecoveryUI::CheckKey(int key, bool is_long_press) {
   {
     std::lock_guard<std::mutex> lg(key_press_mutex);
     key_long_press = false;
   }

   // If we have power and volume up keys, that chord is the signal to toggle the text display.
   if (HasThreeButtons() || (HasPowerKey() && HasTouchScreen() && touch_screen_allowed_)) {
     if ((key == KEY_VOLUMEUP || key == KEY_UP) && IsKeyPressed(KEY_POWER)) {
       return TOGGLE;
     }
   } else {
     // Otherwise long press of any button toggles to the text display,
     // and there's no way to toggle back (but that's pretty useless anyway).
     if (is_long_press && !IsTextVisible()) {
       return TOGGLE;
     }

     // Also, for button-limited devices, a long press is translated to KEY_ENTER.
     if (is_long_press && IsTextVisible()) {
       EnqueueKey(KEY_ENTER);
       return IGNORE;
     }
   }

   // Press power seven times in a row to reboot.
   if (key == KEY_POWER) {
     bool reboot_enabled = enable_reboot;

     if (reboot_enabled) {
       ++consecutive_power_keys;
       if (consecutive_power_keys >= 7) {
         return REBOOT;
       }
     }
   } else {
     consecutive_power_keys = 0;
   }

   return (IsTextVisible() || screensaver_state_ == ScreensaverState::OFF) ? ENQUEUE : IGNORE;
 }

 void RecoveryUI::KeyLongPress(int) {}

 void RecoveryUI::SetEnableReboot(bool enabled) {
   std::lock_guard<std::mutex> lg(key_press_mutex);
   enable_reboot = enabled;
 }
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "recovery_ui/ui.h"

	#include <errno.h>
	#include <fcntl.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/time.h>
	#include <sys/types.h>
	#include <time.h>
	#include <unistd.h>

	#include <chrono>
	#include <functional>
	#include <string>
	#include <thread>

	#include <android-base/file.h>
	#include <android-base/logging.h>
	#include <android-base/parseint.h>
	#include <android-base/properties.h>
	#include <android-base/strings.h>
	#include <volume_manager/VolumeManager.h>

	#include "minui/minui.h"
	#include "otautil/sysutil.h"

	using namespace std::chrono_literals;

	constexpr int UI_WAIT_KEY_TIMEOUT_SEC = 120;
	constexpr const char* DEFAULT_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/brightness";
	constexpr const char* DEFAULT_MAX_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/max_brightness";
	constexpr const char* BRIGHTNESS_FILE_SDM = "/sys/class/backlight/panel0-backlight/brightness";
	constexpr const char* MAX_BRIGHTNESS_FILE_SDM =
	"/sys/class/backlight/panel0-backlight/max_brightness";
	constexpr const char* BRIGHTNESS_FILE_PWM = "/sys/class/backlight/pwm-backlight.0/brightness";
	constexpr const char* MAX_BRIGHTNESS_FILE_PWM =
	"/sys/class/backlight/pwm-backlight.0/max_brightness";

	constexpr int kDefaultTouchLowThreshold = 50;
	constexpr int kDefaultTouchHighThreshold = 90;

	constexpr int kDefaultNormalBrightnessPercent = 50;
	constexpr int kDefaultDimmedBrightnessPercent = 25;

	RecoveryUI::RecoveryUI()
	: brightness_normal_(android::base::GetIntProperty("ro.recovery.ui.brightness_normal_percent",
	kDefaultNormalBrightnessPercent)),
	brightness_dimmed_(android::base::GetIntProperty("ro.recovery.ui.brightness_dimmed_percent",
	kDefaultDimmedBrightnessPercent)),
	brightness_file_(
	android::base::GetProperty("ro.recovery.ui.brightness_file", DEFAULT_BRIGHTNESS_FILE)),
	max_brightness_file_(android::base::GetProperty("ro.recovery.ui.max_brightness_file",
	DEFAULT_MAX_BRIGHTNESS_FILE)),
	touch_screen_allowed_(true),
	fastbootd_logo_enabled_(false),
	sideload_auto_reboot_(false),
	touch_low_threshold_(android::base::GetIntProperty("ro.recovery.ui.touch_low_threshold",
	kDefaultTouchLowThreshold)),
	touch_high_threshold_(android::base::GetIntProperty("ro.recovery.ui.touch_high_threshold",
	kDefaultTouchHighThreshold)),
	key_interrupted_(false),
	event_queue_len(0),
	key_last_down(-1),
	key_long_press(false),
	key_down_count(0),
	enable_reboot(true),
	consecutive_power_keys(0),
	has_power_key(false),
	has_up_key(false),
	has_down_key(false),
	has_touch_screen(false),
	touch_slot_(0),
	touch_finger_down_(false),
	touch_saw_x_(false),
	touch_saw_y_(false),
	touch_reported_(false),
	is_bootreason_recovery_ui_(false),
	screensaver_state_(ScreensaverState::DISABLED) {
	memset(key_pressed, 0, sizeof(key_pressed));
	}

	RecoveryUI::~RecoveryUI() {
	ev_exit();
	input_thread_stopped_ = true;
	if (input_thread_.joinable()) {
	input_thread_.join();
	}
	}

	void RecoveryUI::OnTouchDeviceDetected(int fd) {
	char name[256];
	char path[PATH_MAX];
	char buf[4096];

	memset(name, 0, sizeof(name));
	if (ioctl(fd, EVIOCGNAME(sizeof(name)), name) < 0) {
	return;
	}
	sprintf(path, "/sys/board_properties/virtualkeys.%s", name);
	int vkfd = open(path, O_RDONLY);
	if (vkfd < 0) {
	LOG(INFO) << "vkeys: could not open " << path;
	return;
	}
	ssize_t len = read(vkfd, buf, sizeof(buf));
	close(vkfd);
	if (len <= 0) {
	LOG(ERROR) << "vkeys: could not read " << path;
	return;
	}
	buf[len] = '\0';

	char* p = buf;
	char* endp;
	for (size_t n = 0; p < buf + len && *p == '0'; ++n) {
	int val[6];
	int f;
	for (f = 0; *p && f < 6; ++f) {
	val[f] = strtol(p, &endp, 0);
	if (p == endp) break;
	p = endp + 1;
	}
	if (f != 6 \|\| val[0] != 0x01) break;
	vkey_t vk;
	vk.keycode = val[1];
	vk.min_ = Point(val[2] - val[4] / 2, val[3] - val[5] / 2);
	vk.max_ = Point(val[2] + val[4] / 2, val[3] + val[5] / 2);
	virtual_keys_.push_back(vk);
	}
	}

	void RecoveryUI::OnKeyDetected(int key_code) {
	if (key_code == KEY_POWER) {
	has_power_key = true;
	} else if (key_code == KEY_DOWN \|\| key_code == KEY_VOLUMEDOWN) {
	has_down_key = true;
	} else if (key_code == KEY_UP \|\| key_code == KEY_VOLUMEUP) {
	has_up_key = true;
	} else if (key_code == ABS_MT_POSITION_X \|\| key_code == ABS_MT_POSITION_Y) {
	has_touch_screen = true;
	}
	}

	bool RecoveryUI::InitScreensaver() {
	// Disabled.
	if (brightness_normal_ == 0 \|\| brightness_dimmed_ > brightness_normal_) {
	return false;
	}
	if (access(brightness_file_.c_str(), R_OK \| W_OK)) {
	if (!access(BRIGHTNESS_FILE_SDM, R_OK \| W_OK)) {
	brightness_file_ = BRIGHTNESS_FILE_SDM;
	} else {
	brightness_file_ = BRIGHTNESS_FILE_PWM;
	}
	}

	if (access(max_brightness_file_.c_str(), R_OK)) {
	if (!access(MAX_BRIGHTNESS_FILE_SDM, R_OK)) {
	max_brightness_file_ = MAX_BRIGHTNESS_FILE_SDM;
	} else {
	max_brightness_file_ = MAX_BRIGHTNESS_FILE_PWM;
	}
	}
	// Set the initial brightness level based on the max brightness. Note that reading the initial
	// value from BRIGHTNESS_FILE doesn't give the actual brightness value (bullhead, sailfish), so
	// we don't have a good way to query the default value.
	std::string content;
	if (!android::base::ReadFileToString(max_brightness_file_, &content)) {
	PLOG(WARNING) << "Failed to read max brightness";
	return false;
	}

	unsigned int max_value;
	if (!android::base::ParseUint(android::base::Trim(content), &max_value)) {
	LOG(WARNING) << "Failed to parse max brightness: " << content;
	return false;
	}

	brightness_normal_value_ = max_value * brightness_normal_ / 100.0;
	brightness_dimmed_value_ = max_value * brightness_dimmed_ / 100.0;
	if (!android::base::WriteStringToFile(std::to_string(brightness_normal_value_),
	brightness_file_)) {
	PLOG(WARNING) << "Failed to set brightness";
	return false;
	}

	LOG(INFO) << "Brightness: " << brightness_normal_value_ << " (" << brightness_normal_ << "%)";
	screensaver_state_ = ScreensaverState::NORMAL;
	return true;
	}

	bool RecoveryUI::Init(const std::string& /* locale */) {
	ev_init(std::bind(&RecoveryUI::OnInputEvent, this, std::placeholders::_1, std::placeholders::_2),
	touch_screen_allowed_);

	ev_iterate_available_keys(std::bind(&RecoveryUI::OnKeyDetected, this, std::placeholders::_1));

	if (touch_screen_allowed_) {
	ev_iterate_touch_inputs(
	std::bind(&RecoveryUI::OnTouchDeviceDetected, this, std::placeholders::_1),
	std::bind(&RecoveryUI::OnKeyDetected, this, std::placeholders::_1));

	// Parse /proc/cmdline to determine if it's booting into recovery with a bootreason of
	// "recovery_ui". This specific reason is set by some (wear) bootloaders, to allow an easier way
	// to turn on text mode. It will only be set if the recovery boot is triggered from fastboot, or
	// with 'adb reboot recovery'. Note that this applies to all build variants. Otherwise the text
	// mode will be turned on automatically on debuggable builds, even without a swipe.
	std::string cmdline;
	if (android::base::ReadFileToString("/proc/cmdline", &cmdline)) {
	is_bootreason_recovery_ui_ = cmdline.find("bootreason=recovery_ui") != std::string::npos;
	} else {
	// Non-fatal, and won't affect Init() result.
	PLOG(WARNING) << "Failed to read /proc/cmdline";
	}
	}

	if (!InitScreensaver()) {
	LOG(INFO) << "Screensaver disabled";
	}

	// Create a separate thread that handles input events.
	input_thread_ = std::thread([this]() {
	while (!this->input_thread_stopped_) {
	if (!ev_wait(500)) {
	ev_dispatch();
	}
	}
	});

	return true;
	}

	void RecoveryUI::CalibrateTouch(int fd) {
	struct input_absinfo info;
	static bool calibrated = false;

	if (calibrated) return;

	memset(&info, 0, sizeof(info));
	if (ioctl(fd, EVIOCGABS(ABS_MT_POSITION_X), &info) == 0) {
	touch_min_.x(info.minimum);
	touch_max_.x(info.maximum);
	}
	memset(&info, 0, sizeof(info));
	if (ioctl(fd, EVIOCGABS(ABS_MT_POSITION_Y), &info) == 0) {
	touch_min_.y(info.minimum);
	touch_max_.y(info.maximum);
	}

	calibrated = true;
	}

	void RecoveryUI::OnTouchPress() {
	touch_start_ = touch_track_ = touch_pos_;
	}

	void RecoveryUI::OnTouchTrack() {
	if (touch_pos_.y() <= gr_fb_height_real()) {
	while (abs(touch_pos_.y() - touch_track_.y()) >= MenuItemHeight()) {
	int dy = touch_pos_.y() - touch_track_.y();
	int key = (dy < 0) ? KEY_SCROLLDOWN : KEY_SCROLLUP;
	ProcessKey(key, 1); // press key
	ProcessKey(key, 0); // and release it
	int sgn = (dy > 0) - (dy < 0);
	touch_track_.y(touch_track_.y() + sgn * MenuItemHeight());
	}
	}
	}

	void RecoveryUI::OnTouchRelease() {
	// Allow turning on text mode with any swipe, if bootloader has set a bootreason of recovery_ui.
	if (is_bootreason_recovery_ui_ && !IsTextVisible()) {
	ShowText(true);
	return;
	}

	// Check vkeys. Only report if touch both starts and ends in the vkey.
	if (touch_start_.y() > gr_fb_height_real() && touch_pos_.y() > gr_fb_height_real()) {
	for (const auto& vk : virtual_keys_) {
	if (vk.inside(touch_start_) && vk.inside(touch_pos_)) {
	ProcessKey(vk.keycode, 1); // press key
	ProcessKey(vk.keycode, 0); // and release it
	}
	}
	return;
	}

	// If we tracked a vertical swipe, ignore the release
	if (touch_track_ != touch_start_) {
	return;
	}

	// Simple touch
	EnqueueTouch(touch_pos_);
	}

	int RecoveryUI::OnInputEvent(int fd, uint32_t epevents) {
	struct input_event ev;
	if (ev_get_input(fd, epevents, &ev) == -1) {
	return -1;
	}

	// Touch inputs handling.
	//
	// Per the doc Multi-touch Protocol at below, there are two protocols.
	// https://www.kernel.org/doc/Documentation/input/multi-touch-protocol.txt
	//
	// The main difference between the stateless type A protocol and the stateful type B slot protocol
	// lies in the usage of identifiable contacts to reduce the amount of data sent to userspace. The
	// slot protocol (i.e. type B) sends ABS_MT_TRACKING_ID with a unique id on initial contact, and
	// sends ABS_MT_TRACKING_ID -1 upon lifting the contact. Protocol A doesn't send
	// ABS_MT_TRACKING_ID -1 on lifting, but the driver may additionally report BTN_TOUCH event.
	//
	// For protocol A, we rely on BTN_TOUCH to recognize lifting, while for protocol B we look for
	// ABS_MT_TRACKING_ID being -1.
	//
	// Touch input events will only be available if touch_screen_allowed_ is set.

	if (ev.type == EV_SYN) {
	if (touch_screen_allowed_ && ev.code == SYN_REPORT) {
	// There might be multiple SYN_REPORT events. Only report press/release once.
	if (!touch_reported_ && touch_finger_down_) {
	if (touch_saw_x_ && touch_saw_y_) {
	OnTouchPress();
	touch_reported_ = true;
	touch_saw_x_ = touch_saw_y_ = false;
	}
	} else if (touch_reported_ && !touch_finger_down_) {
	OnTouchRelease();
	touch_reported_ = false;
	touch_saw_x_ = touch_saw_y_ = false;
	}
	}
	return 0;
	}

	if (ev.type == EV_REL) {
	if (ev.code == REL_Y) {
	// accumulate the up or down motion reported by
	// the trackball. When it exceeds a threshold
	// (positive or negative), fake an up/down
	// key event.
	rel_sum += ev.value;
	if (rel_sum > 3) {
	ProcessKey(KEY_DOWN, 1); // press down key
	ProcessKey(KEY_DOWN, 0); // and release it
	rel_sum = 0;
	} else if (rel_sum < -3) {
	ProcessKey(KEY_UP, 1); // press up key
	ProcessKey(KEY_UP, 0); // and release it
	rel_sum = 0;
	}
	}
	} else {
	rel_sum = 0;
	}

	if (touch_screen_allowed_ && ev.type == EV_ABS) {
	CalibrateTouch(fd);
	if (ev.code == ABS_MT_SLOT) {
	touch_slot_ = ev.value;
	}
	// Ignore other fingers.
	if (touch_slot_ > 0) return 0;

	switch (ev.code) {
	case ABS_MT_POSITION_X:
	touch_finger_down_ = true;
	touch_saw_x_ = true;
	touch_pos_.x(ev.value * gr_fb_width_real() / (touch_max_.x() - touch_min_.x()));
	if (touch_reported_ && touch_saw_y_) {
	OnTouchTrack();
	touch_saw_x_ = touch_saw_y_ = false;
	}
	break;

	case ABS_MT_POSITION_Y:
	touch_finger_down_ = true;
	touch_saw_y_ = true;
	touch_pos_.y(ev.value * gr_fb_height_real() / (touch_max_.y() - touch_min_.y()));
	if (touch_reported_ && touch_saw_x_) {
	OnTouchTrack();
	touch_saw_x_ = touch_saw_y_ = false;
	}
	break;

	case ABS_MT_TRACKING_ID:
	// Protocol B: -1 marks lifting the contact.
	if (ev.value < 0) touch_finger_down_ = false;
	break;
	}
	return 0;
	}

	if (ev.type == EV_KEY && ev.code <= KEY_MAX) {
	if (touch_screen_allowed_) {
	if (ev.code == BTN_TOUCH) {
	// A BTN_TOUCH with value 1 indicates the start of contact (protocol A), with 0 means
	// lifting the contact.
	touch_finger_down_ = (ev.value == 1);
	}

	// Intentionally ignore BTN_TOUCH and BTN_TOOL_FINGER, which would otherwise trigger
	// additional scrolling (because in ScreenRecoveryUI::ShowFile(), we consider keys other than
	// KEY_POWER and KEY_UP as KEY_DOWN).
	if (ev.code == BTN_TOUCH \|\| ev.code == BTN_TOOL_FINGER) {
	return 0;
	}
	}

	ProcessKey(ev.code, ev.value);
	}

	// For Lid switch handle
	if (ev.type == EV_SW) {
	SetSwCallback(ev.code, ev.value);
	}

	return 0;
	}

	// Processes a key-up or -down event. A key is "registered" when it is pressed and then released,
	// with no other keypresses or releases in between. Registered keys are passed to CheckKey() to
	// see if it should trigger a visibility toggle, an immediate reboot, or be queued to be processed
	// next time the foreground thread wants a key (eg, for the menu).
	//
	// We also keep track of which keys are currently down so that CheckKey() can call IsKeyPressed()
	// to see what other keys are held when a key is registered.
	//
	// updown == 1 for key down events; 0 for key up events
	void RecoveryUI::ProcessKey(int key_code, int updown) {
	bool register_key = false;
	bool long_press = false;

	{
	std::lock_guard<std::mutex> lg(key_press_mutex);
	key_pressed[key_code] = updown;
	if (updown) {
	++key_down_count;
	key_last_down = key_code;
	key_long_press = false;
	std::thread time_key_thread(&RecoveryUI::TimeKey, this, key_code, key_down_count);
	time_key_thread.detach();
	} else {
	if (key_last_down == key_code) {
	long_press = key_long_press;
	register_key = true;
	}
	key_last_down = -1;
	}
	}

	bool reboot_enabled = enable_reboot;
	if (register_key) {
	switch (CheckKey(key_code, long_press)) {
	case RecoveryUI::IGNORE:
	break;

	case RecoveryUI::TOGGLE:
	ShowText(!IsTextVisible());
	break;

	case RecoveryUI::REBOOT:
	if (reboot_enabled) {
	android::volmgr::VolumeManager::Instance()->unmountAll();
	Reboot("userrequested,recovery,ui");
	}
	break;

	case RecoveryUI::ENQUEUE:
	EnqueueKey(key_code);
	break;
	}
	}
	}

	void RecoveryUI::TimeKey(int key_code, int count) {
	std::this_thread::sleep_for(750ms); // 750 ms == "long"
	bool long_press = false;
	{
	std::lock_guard<std::mutex> lg(key_press_mutex);
	if (key_last_down == key_code && key_down_count == count) {
	long_press = key_long_press = true;
	}
	}
	if (long_press) KeyLongPress(key_code);
	}

	void RecoveryUI::EnqueueKey(int key_code) {
	std::lock_guard<std::mutex> lg(event_queue_mutex);
	const int queue_max = sizeof(event_queue) / sizeof(event_queue[0]);
	if (event_queue_len < queue_max) {
	InputEvent event(key_code);
	event_queue[event_queue_len++] = event;
	event_queue_cond.notify_one();
	}
	}

	void RecoveryUI::EnqueueTouch(const Point& pos) {
	std::lock_guard<std::mutex> lg(event_queue_mutex);
	const int queue_max = sizeof(event_queue) / sizeof(event_queue[0]);
	if (event_queue_len < queue_max) {
	InputEvent event(pos);
	event_queue[event_queue_len++] = event;
	event_queue_cond.notify_one();
	}
	}

	void RecoveryUI::SetScreensaverState(ScreensaverState state) {
	switch (state) {
	case ScreensaverState::NORMAL:
	if (android::base::WriteStringToFile(std::to_string(brightness_normal_value_),
	brightness_file_)) {
	screensaver_state_ = ScreensaverState::NORMAL;
	LOG(INFO) << "Brightness: " << brightness_normal_value_ << " (" << brightness_normal_
	<< "%)";
	} else {
	LOG(WARNING) << "Unable to set brightness to normal";
	}
	break;
	case ScreensaverState::DIMMED:
	if (android::base::WriteStringToFile(std::to_string(brightness_dimmed_value_),
	brightness_file_)) {
	LOG(INFO) << "Brightness: " << brightness_dimmed_value_ << " (" << brightness_dimmed_
	<< "%)";
	screensaver_state_ = ScreensaverState::DIMMED;
	} else {
	LOG(WARNING) << "Unable to set brightness to dim";
	}
	break;
	case ScreensaverState::OFF:
	if (android::base::WriteStringToFile("0", brightness_file_)) {
	LOG(INFO) << "Brightness: 0 (off)";
	screensaver_state_ = ScreensaverState::OFF;
	} else {
	LOG(WARNING) << "Unable to set brightness to off";
	}
	break;
	default:
	LOG(ERROR) << "Invalid screensaver state";
	}
	}

	RecoveryUI::InputEvent RecoveryUI::WaitInputEvent() {
	std::unique_lock<std::mutex> lk(event_queue_mutex);

	// Check for a saved key queue interruption.
	if (key_interrupted_) {
	SetScreensaverState(ScreensaverState::NORMAL);
	return InputEvent(EventType::EXTRA, KeyError::INTERRUPTED);
	}

	// Time out after UI_WAIT_KEY_TIMEOUT_SEC, unless a USB cable is plugged in.
	do {
	bool rc = event_queue_cond.wait_for(lk, std::chrono::seconds(UI_WAIT_KEY_TIMEOUT_SEC), [this] {
	return this->event_queue_len != 0 \|\| key_interrupted_;
	});
	if (key_interrupted_) {
	SetScreensaverState(ScreensaverState::NORMAL);
	return InputEvent(EventType::EXTRA, KeyError::INTERRUPTED);
	}
	if (screensaver_state_ != ScreensaverState::DISABLED) {
	if (!rc) {
	// Must be after a timeout. Lower the brightness level: NORMAL -> DIMMED; DIMMED -> OFF.
	if (screensaver_state_ == ScreensaverState::NORMAL) {
	SetScreensaverState(ScreensaverState::DIMMED);
	} else if (screensaver_state_ == ScreensaverState::DIMMED) {
	SetScreensaverState(ScreensaverState::OFF);
	}
	} else if (screensaver_state_ != ScreensaverState::NORMAL) {
	// Drop the first key if it's changing from OFF to NORMAL.
	if (screensaver_state_ == ScreensaverState::OFF) {
	if (event_queue_len > 0) {
	memcpy(&event_queue[0], &event_queue[1], sizeof(int) * --event_queue_len);
	}
	}

	// Reset the brightness to normal.
	SetScreensaverState(ScreensaverState::NORMAL);
	}
	}
	} while (IsUsbConnected() && event_queue_len == 0);

	InputEvent event;
	if (event_queue_len > 0) {
	event = event_queue[0];
	memcpy(&event_queue[0], &event_queue[1], sizeof(InputEvent) * --event_queue_len);
	}
	return event;
	}

	void RecoveryUI::CancelWaitKey() {
	EnqueueKey(KEY_AGAIN);
	}

	void RecoveryUI::InterruptKey() {
	{
	std::lock_guard<std::mutex> lg(event_queue_mutex);
	key_interrupted_ = true;
	}
	event_queue_cond.notify_one();
	}

	bool RecoveryUI::IsUsbConnected() {
	int fd = open("/sys/class/android_usb/android0/state", O_RDONLY);
	if (fd < 0) {
	printf("failed to open /sys/class/android_usb/android0/state: %s\n", strerror(errno));
	return 0;
	}

	char buf;
	// USB is connected if android_usb state is CONNECTED or CONFIGURED.
	int connected = (TEMP_FAILURE_RETRY(read(fd, &buf, 1)) == 1) && (buf == 'C');
	if (close(fd) < 0) {
	printf("failed to close /sys/class/android_usb/android0/state: %s\n", strerror(errno));
	}
	return connected;
	}

	bool RecoveryUI::IsKeyPressed(int key) {
	std::lock_guard<std::mutex> lg(key_press_mutex);
	int pressed = key_pressed[key];
	return pressed;
	}

	bool RecoveryUI::IsLongPress() {
	std::lock_guard<std::mutex> lg(key_press_mutex);
	bool result = key_long_press;
	return result;
	}

	bool RecoveryUI::HasThreeButtons() const {
	return has_power_key && has_up_key && has_down_key;
	}

	bool RecoveryUI::HasPowerKey() const {
	return has_power_key;
	}

	bool RecoveryUI::HasTouchScreen() const {
	return has_touch_screen;
	}

	void RecoveryUI::FlushKeys() {
	std::lock_guard<std::mutex> lg(event_queue_mutex);
	event_queue_len = 0;
	}

	RecoveryUI::KeyAction RecoveryUI::CheckKey(int key, bool is_long_press) {
	{
	std::lock_guard<std::mutex> lg(key_press_mutex);
	key_long_press = false;
	}

	// If we have power and volume up keys, that chord is the signal to toggle the text display.
	if (HasThreeButtons() \|\| (HasPowerKey() && HasTouchScreen() && touch_screen_allowed_)) {
	if ((key == KEY_VOLUMEUP \|\| key == KEY_UP) && IsKeyPressed(KEY_POWER)) {
	return TOGGLE;
	}
	} else {
	// Otherwise long press of any button toggles to the text display,
	// and there's no way to toggle back (but that's pretty useless anyway).
	if (is_long_press && !IsTextVisible()) {
	return TOGGLE;
	}

	// Also, for button-limited devices, a long press is translated to KEY_ENTER.
	if (is_long_press && IsTextVisible()) {
	EnqueueKey(KEY_ENTER);
	return IGNORE;
	}
	}

	// Press power seven times in a row to reboot.
	if (key == KEY_POWER) {
	bool reboot_enabled = enable_reboot;

	if (reboot_enabled) {
	++consecutive_power_keys;
	if (consecutive_power_keys >= 7) {
	return REBOOT;
	}
	}
	} else {
	consecutive_power_keys = 0;
	}

	return (IsTextVisible() \|\| screensaver_state_ == ScreensaverState::OFF) ? ENQUEUE : IGNORE;
	}

	void RecoveryUI::KeyLongPress(int) {}

	void RecoveryUI::SetEnableReboot(bool enabled) {
	std::lock_guard<std::mutex> lg(key_press_mutex);
	enable_reboot = enabled;
	}