ui.cpp - platform/bootable/recovery - Git at Google

 /*
  * 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 "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/strings.h>

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

 using namespace std::chrono_literals;

 static constexpr int UI_WAIT_KEY_TIMEOUT_SEC = 120;
 static constexpr const char* BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/brightness";
 static constexpr const char* MAX_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/max_brightness";
 static constexpr const char* BRIGHTNESS_FILE_SDM =
     "/sys/class/backlight/panel0-backlight/brightness";
 static constexpr const char* MAX_BRIGHTNESS_FILE_SDM =
     "/sys/class/backlight/panel0-backlight/max_brightness";

 RecoveryUI::RecoveryUI()
     : brightness_normal_(50),
       brightness_dimmed_(25),
       brightness_file_(BRIGHTNESS_FILE),
       max_brightness_file_(MAX_BRIGHTNESS_FILE),
       touch_screen_allowed_(false),
       kTouchLowThreshold(RECOVERY_UI_TOUCH_LOW_THRESHOLD),
       kTouchHighThreshold(RECOVERY_UI_TOUCH_HIGH_THRESHOLD),
       key_queue_len(0),
       key_last_down(-1),
       key_long_press(false),
       key_down_count(0),
       enable_reboot(true),
       consecutive_power_keys(0),
       last_key(-1),
       has_power_key(false),
       has_up_key(false),
       has_down_key(false),
       has_touch_screen(false),
       touch_slot_(0),
       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::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)) {
     brightness_file_ = BRIGHTNESS_FILE_SDM;
   }
   if (access(max_brightness_file_.c_str(), R_OK)) {
     max_brightness_file_ = MAX_BRIGHTNESS_FILE_SDM;
   }
   // 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::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::OnTouchDetected(int dx, int dy) {
   enum SwipeDirection { UP, DOWN, RIGHT, LEFT } direction;

   // We only consider a valid swipe if:
   // - the delta along one axis is below kTouchLowThreshold;
   // - and the delta along the other axis is beyond kTouchHighThreshold.
   if (abs(dy) < kTouchLowThreshold && abs(dx) > kTouchHighThreshold) {
     direction = dx < 0 ? SwipeDirection::LEFT : SwipeDirection::RIGHT;
   } else if (abs(dx) < kTouchLowThreshold && abs(dy) > kTouchHighThreshold) {
     direction = dy < 0 ? SwipeDirection::UP : SwipeDirection::DOWN;
   } else {
     LOG(DEBUG) << "Ignored " << dx << " " << dy << " (low: " << kTouchLowThreshold
                << ", high: " << kTouchHighThreshold << ")";
     return;
   }

   // 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;
   }

   LOG(DEBUG) << "Swipe direction=" << direction;
   switch (direction) {
     case SwipeDirection::UP:
       ProcessKey(KEY_UP, 1);  // press up key
       ProcessKey(KEY_UP, 0);  // and release it
       break;

     case SwipeDirection::DOWN:
       ProcessKey(KEY_DOWN, 1);  // press down key
       ProcessKey(KEY_DOWN, 0);  // and release it
       break;

     case SwipeDirection::LEFT:
     case SwipeDirection::RIGHT:
       ProcessKey(KEY_POWER, 1);  // press power key
       ProcessKey(KEY_POWER, 0);  // and release it
       break;
   };
 }

 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.
   //
   // We handle the touch inputs by tracking the position changes between initial contacting and
   // upon lifting. touch_start_X/Y record the initial positions, with touch_finger_down set. Upon
   // detecting the lift, we unset touch_finger_down and detect a swipe based on position changes.
   //
   // 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. We should only detect a swipe after lifting the
       // contact.
       if (touch_finger_down_ && !touch_swiping_) {
         touch_start_X_ = touch_X_;
         touch_start_Y_ = touch_Y_;
         touch_swiping_ = true;
       } else if (!touch_finger_down_ && touch_swiping_) {
         touch_swiping_ = false;
         OnTouchDetected(touch_X_ - touch_start_X_, touch_Y_ - touch_start_Y_);
       }
     }
     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) {
     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_X_ = ev.value;
         touch_finger_down_ = true;
         break;

       case ABS_MT_POSITION_Y:
         touch_Y_ = ev.value;
         touch_finger_down_ = true;
         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);
   }

   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_queue_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) {
           reboot("reboot,");
           while (true) {
             pause();
           }
         }
         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_queue_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(key_queue_mutex);
   const int queue_max = sizeof(key_queue) / sizeof(key_queue[0]);
   if (key_queue_len < queue_max) {
     key_queue[key_queue_len++] = key_code;
     key_queue_cond.notify_one();
   }
 }

 int RecoveryUI::WaitKey() {
   std::unique_lock<std::mutex> lk(key_queue_mutex);

   // Time out after UI_WAIT_KEY_TIMEOUT_SEC, unless a USB cable is
   // plugged in.
   do {
     std::cv_status rc = std::cv_status::no_timeout;
     while (key_queue_len == 0 && rc != std::cv_status::timeout) {
       rc = key_queue_cond.wait_for(lk, std::chrono::seconds(UI_WAIT_KEY_TIMEOUT_SEC));
     }

     if (screensaver_state_ != ScreensaverState::DISABLED) {
       if (rc == std::cv_status::timeout) {
         // Lower the brightness level: NORMAL -> DIMMED; DIMMED -> OFF.
         if (screensaver_state_ == ScreensaverState::NORMAL) {
           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 if (screensaver_state_ == ScreensaverState::DIMMED) {
           if (android::base::WriteStringToFile("0", brightness_file_)) {
             LOG(INFO) << "Brightness: 0 (off)";
             screensaver_state_ = 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 (key_queue_len > 0) {
             memcpy(&key_queue[0], &key_queue[1], sizeof(int) * --key_queue_len);
           }
         }

         // Reset the brightness to 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_
                     << "%)";
         }
       }
     }
   } while (IsUsbConnected() && key_queue_len == 0);

   int key = -1;
   if (key_queue_len > 0) {
     key = key_queue[0];
     memcpy(&key_queue[0], &key_queue[1], sizeof(int) * --key_queue_len);
   }
   return key;
 }

 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_queue_mutex);
   int pressed = key_pressed[key];
   return pressed;
 }

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

 bool RecoveryUI::HasThreeButtons() {
   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(key_queue_mutex);
   key_queue_len = 0;
 }

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

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

 void RecoveryUI::KeyLongPress(int) {
 }

 void RecoveryUI::SetEnableReboot(bool enabled) {
   std::lock_guard<std::mutex> lg(key_queue_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 "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/strings.h>

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

	using namespace std::chrono_literals;

	static constexpr int UI_WAIT_KEY_TIMEOUT_SEC = 120;
	static constexpr const char* BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/brightness";
	static constexpr const char* MAX_BRIGHTNESS_FILE = "/sys/class/leds/lcd-backlight/max_brightness";
	static constexpr const char* BRIGHTNESS_FILE_SDM =
	"/sys/class/backlight/panel0-backlight/brightness";
	static constexpr const char* MAX_BRIGHTNESS_FILE_SDM =
	"/sys/class/backlight/panel0-backlight/max_brightness";

	RecoveryUI::RecoveryUI()
	: brightness_normal_(50),
	brightness_dimmed_(25),
	brightness_file_(BRIGHTNESS_FILE),
	max_brightness_file_(MAX_BRIGHTNESS_FILE),
	touch_screen_allowed_(false),
	kTouchLowThreshold(RECOVERY_UI_TOUCH_LOW_THRESHOLD),
	kTouchHighThreshold(RECOVERY_UI_TOUCH_HIGH_THRESHOLD),
	key_queue_len(0),
	key_last_down(-1),
	key_long_press(false),
	key_down_count(0),
	enable_reboot(true),
	consecutive_power_keys(0),
	last_key(-1),
	has_power_key(false),
	has_up_key(false),
	has_down_key(false),
	has_touch_screen(false),
	touch_slot_(0),
	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::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)) {
	brightness_file_ = BRIGHTNESS_FILE_SDM;
	}
	if (access(max_brightness_file_.c_str(), R_OK)) {
	max_brightness_file_ = MAX_BRIGHTNESS_FILE_SDM;
	}
	// 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::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::OnTouchDetected(int dx, int dy) {
	enum SwipeDirection { UP, DOWN, RIGHT, LEFT } direction;

	// We only consider a valid swipe if:
	// - the delta along one axis is below kTouchLowThreshold;
	// - and the delta along the other axis is beyond kTouchHighThreshold.
	if (abs(dy) < kTouchLowThreshold && abs(dx) > kTouchHighThreshold) {
	direction = dx < 0 ? SwipeDirection::LEFT : SwipeDirection::RIGHT;
	} else if (abs(dx) < kTouchLowThreshold && abs(dy) > kTouchHighThreshold) {
	direction = dy < 0 ? SwipeDirection::UP : SwipeDirection::DOWN;
	} else {
	LOG(DEBUG) << "Ignored " << dx << " " << dy << " (low: " << kTouchLowThreshold
	<< ", high: " << kTouchHighThreshold << ")";
	return;
	}

	// 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;
	}

	LOG(DEBUG) << "Swipe direction=" << direction;
	switch (direction) {
	case SwipeDirection::UP:
	ProcessKey(KEY_UP, 1); // press up key
	ProcessKey(KEY_UP, 0); // and release it
	break;

	case SwipeDirection::DOWN:
	ProcessKey(KEY_DOWN, 1); // press down key
	ProcessKey(KEY_DOWN, 0); // and release it
	break;

	case SwipeDirection::LEFT:
	case SwipeDirection::RIGHT:
	ProcessKey(KEY_POWER, 1); // press power key
	ProcessKey(KEY_POWER, 0); // and release it
	break;
	};
	}

	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.
	//
	// We handle the touch inputs by tracking the position changes between initial contacting and
	// upon lifting. touch_start_X/Y record the initial positions, with touch_finger_down set. Upon
	// detecting the lift, we unset touch_finger_down and detect a swipe based on position changes.
	//
	// 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. We should only detect a swipe after lifting the
	// contact.
	if (touch_finger_down_ && !touch_swiping_) {
	touch_start_X_ = touch_X_;
	touch_start_Y_ = touch_Y_;
	touch_swiping_ = true;
	} else if (!touch_finger_down_ && touch_swiping_) {
	touch_swiping_ = false;
	OnTouchDetected(touch_X_ - touch_start_X_, touch_Y_ - touch_start_Y_);
	}
	}
	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) {
	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_X_ = ev.value;
	touch_finger_down_ = true;
	break;

	case ABS_MT_POSITION_Y:
	touch_Y_ = ev.value;
	touch_finger_down_ = true;
	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);
	}

	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_queue_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) {
	reboot("reboot,");
	while (true) {
	pause();
	}
	}
	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_queue_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(key_queue_mutex);
	const int queue_max = sizeof(key_queue) / sizeof(key_queue[0]);
	if (key_queue_len < queue_max) {
	key_queue[key_queue_len++] = key_code;
	key_queue_cond.notify_one();
	}
	}

	int RecoveryUI::WaitKey() {
	std::unique_lock<std::mutex> lk(key_queue_mutex);

	// Time out after UI_WAIT_KEY_TIMEOUT_SEC, unless a USB cable is
	// plugged in.
	do {
	std::cv_status rc = std::cv_status::no_timeout;
	while (key_queue_len == 0 && rc != std::cv_status::timeout) {
	rc = key_queue_cond.wait_for(lk, std::chrono::seconds(UI_WAIT_KEY_TIMEOUT_SEC));
	}

	if (screensaver_state_ != ScreensaverState::DISABLED) {
	if (rc == std::cv_status::timeout) {
	// Lower the brightness level: NORMAL -> DIMMED; DIMMED -> OFF.
	if (screensaver_state_ == ScreensaverState::NORMAL) {
	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 if (screensaver_state_ == ScreensaverState::DIMMED) {
	if (android::base::WriteStringToFile("0", brightness_file_)) {
	LOG(INFO) << "Brightness: 0 (off)";
	screensaver_state_ = 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 (key_queue_len > 0) {
	memcpy(&key_queue[0], &key_queue[1], sizeof(int) * --key_queue_len);
	}
	}

	// Reset the brightness to 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_
	<< "%)";
	}
	}
	}
	} while (IsUsbConnected() && key_queue_len == 0);

	int key = -1;
	if (key_queue_len > 0) {
	key = key_queue[0];
	memcpy(&key_queue[0], &key_queue[1], sizeof(int) * --key_queue_len);
	}
	return key;
	}

	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_queue_mutex);
	int pressed = key_pressed[key];
	return pressed;
	}

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

	bool RecoveryUI::HasThreeButtons() {
	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(key_queue_mutex);
	key_queue_len = 0;
	}

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

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

	void RecoveryUI::KeyLongPress(int) {
	}

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