/*
 * Copyright (C) 2012 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 "install/adb_install.h"

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include <atomic>
#include <functional>
#include <map>

#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/memory.h>
#include <android-base/properties.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>

#include "fuse_sideload.h"
#include "install/install.h"
#include "minadbd_types.h"
#include "recovery_ui/ui.h"

using CommandFunction = std::function<bool()>;

static bool SetUsbConfig(const std::string& state) {
  android::base::SetProperty("sys.usb.config", state);
  return android::base::WaitForProperty("sys.usb.state", state);
}

// Parses the minadbd command in |message|; returns MinadbdCommands::kError upon errors.
static MinadbdCommands ParseMinadbdCommands(const std::string& message) {
  if (!android::base::StartsWith(message, kMinadbdCommandPrefix)) {
    LOG(ERROR) << "Failed to parse command in message " << message;
    return MinadbdCommands::kError;
  }

  auto cmd_code_string = message.substr(strlen(kMinadbdCommandPrefix));
  auto cmd_code = android::base::get_unaligned<uint32_t>(cmd_code_string.c_str());
  if (cmd_code >= static_cast<uint32_t>(MinadbdCommands::kError)) {
    LOG(ERROR) << "Unsupported command code: " << cmd_code;
    return MinadbdCommands::kError;
  }

  return static_cast<MinadbdCommands>(cmd_code);
}

static bool WriteStatusToFd(MinadbdCommandStatus status, int fd) {
  char message[kMinadbdMessageSize];
  memcpy(message, kMinadbdStatusPrefix, strlen(kMinadbdStatusPrefix));
  android::base::put_unaligned(message + strlen(kMinadbdStatusPrefix), status);

  if (!android::base::WriteFully(fd, message, kMinadbdMessageSize)) {
    PLOG(ERROR) << "Failed to write message " << message;
    return false;
  }
  return true;
}

// Installs the package from FUSE. Returns true if the installation succeeds, and false otherwise.
static bool AdbInstallPackageHandler(RecoveryUI* ui, int* result) {
  // How long (in seconds) we wait for the package path to be ready. It doesn't need to be too long
  // because the minadbd service has already issued an install command. FUSE_SIDELOAD_HOST_PATHNAME
  // will start to exist once the host connects and starts serving a package. Poll for its
  // appearance. (Note that inotify doesn't work with FUSE.)
  constexpr int ADB_INSTALL_TIMEOUT = 15;
  *result = INSTALL_ERROR;
  for (int i = 0; i < ADB_INSTALL_TIMEOUT; ++i) {
    struct stat st;
    if (stat(FUSE_SIDELOAD_HOST_PATHNAME, &st) != 0) {
      if (errno == ENOENT && i < ADB_INSTALL_TIMEOUT - 1) {
        sleep(1);
        continue;
      } else {
        ui->Print("\nTimed out waiting for fuse to be ready.\n\n");
        break;
      }
    }
    *result = install_package(FUSE_SIDELOAD_HOST_PATHNAME, false, false, 0, ui);
    break;
  }

  // Calling stat() on this magic filename signals the FUSE to exit.
  struct stat st;
  stat(FUSE_SIDELOAD_HOST_EXIT_PATHNAME, &st);
  return *result == INSTALL_SUCCESS;
}

// Parses and executes the command from minadbd. Returns false if we enter an invalid state so that
// the caller can kill the minadbd service properly.
static bool HandleMessageFromMinadbd(
    int socket_fd, const std::map<MinadbdCommands, CommandFunction>& command_map) {
  char buffer[kMinadbdMessageSize];
  if (!android::base::ReadFully(socket_fd, buffer, kMinadbdMessageSize)) {
    PLOG(ERROR) << "Failed to read message from minadbd";
    return false;
  }

  std::string message(buffer, buffer + kMinadbdMessageSize);
  auto command_type = ParseMinadbdCommands(message);
  if (command_type == MinadbdCommands::kError) {
    return false;
  }
  if (command_map.find(command_type) == command_map.end()) {
    LOG(ERROR) << "Unsupported command: "
               << android::base::get_unaligned<unsigned int>(
                      message.substr(strlen(kMinadbdCommandPrefix)).c_str());
    return false;
  }

  // We have received a valid command, execute the corresponding function.
  const auto& command_func = command_map.at(command_type);
  if (!command_func()) {
    LOG(ERROR) << "Failed to execute command " << static_cast<unsigned int>(command_type);
    return WriteStatusToFd(MinadbdCommandStatus::kFailure, socket_fd);
  }
  return WriteStatusToFd(MinadbdCommandStatus::kSuccess, socket_fd);
}

// TODO(xunchang) add a wrapper function and kill the minadbd service there.
static void ListenAndExecuteMinadbdCommands(
    pid_t minadbd_pid, android::base::unique_fd&& socket_fd,
    const std::map<MinadbdCommands, CommandFunction>& command_map) {
  android::base::unique_fd epoll_fd(epoll_create1(O_CLOEXEC));
  if (epoll_fd == -1) {
    PLOG(ERROR) << "Failed to create epoll";
    kill(minadbd_pid, SIGKILL);
    return;
  }

  constexpr int EPOLL_MAX_EVENTS = 10;
  struct epoll_event ev = {};
  ev.events = EPOLLIN | EPOLLHUP;
  ev.data.fd = socket_fd.get();
  struct epoll_event events[EPOLL_MAX_EVENTS];
  if (epoll_ctl(epoll_fd.get(), EPOLL_CTL_ADD, socket_fd.get(), &ev) == -1) {
    PLOG(ERROR) << "Failed to add socket fd to epoll";
    kill(minadbd_pid, SIGKILL);
    return;
  }

  // Set the timeout to be 300s when waiting for minadbd commands.
  constexpr int TIMEOUT_MILLIS = 300 * 1000;
  while (true) {
    // Poll for the status change of the socket_fd, and handle the message if the fd is ready to
    // read.
    int event_count =
        TEMP_FAILURE_RETRY(epoll_wait(epoll_fd.get(), events, EPOLL_MAX_EVENTS, TIMEOUT_MILLIS));
    if (event_count == -1) {
      PLOG(ERROR) << "Failed to wait for epoll events";
      kill(minadbd_pid, SIGKILL);
      return;
    }
    if (event_count == 0) {
      LOG(ERROR) << "Timeout waiting for messages from minadbd";
      kill(minadbd_pid, SIGKILL);
      return;
    }

    for (int n = 0; n < event_count; n++) {
      if (events[n].events & EPOLLHUP) {
        LOG(INFO) << "Socket has been closed";
        kill(minadbd_pid, SIGKILL);
        return;
      }
      if (!HandleMessageFromMinadbd(socket_fd.get(), command_map)) {
        kill(minadbd_pid, SIGKILL);
        return;
      }
    }
  }
}

// Recovery starts minadbd service as a child process, and spawns another thread to listen for the
// message from minadbd through a socket pair. Here is an example to execute one command from adb
// host.
//  a. recovery                    b. listener thread               c. minadbd service
//
//  a1. create socket pair
//  a2. fork minadbd service
//                                                                c3. wait for the adb commands
//                                                                    from host
//                                                                c4. after receiving host commands:
//                                                                  1) set up pre-condition (i.e.
//                                                                     start fuse for adb sideload)
//                                                                  2) issue command through
//                                                                     socket.
//                                                                  3) wait for result
//  a5. start listener thread
//                               b6. listen for message from
//                                   minadbd in a loop.
//                               b7. After receiving a minadbd
//                                   command from socket
//                                 1) execute the command function
//                                 2) send the result back to
//                                    minadbd
//  ......
//                                                                 c8. exit upon receiving the
//                                                                     result
// a9.  wait for listener thread
//      to exit.
//
// a10. wait for minadbd to
//      exit
//                               b11. exit the listening loop
//
static void CreateMinadbdServiceAndExecuteCommands(
    const std::map<MinadbdCommands, CommandFunction>& command_map) {
  signal(SIGPIPE, SIG_IGN);

  android::base::unique_fd recovery_socket;
  android::base::unique_fd minadbd_socket;
  if (!android::base::Socketpair(AF_UNIX, SOCK_STREAM, 0, &recovery_socket, &minadbd_socket)) {
    PLOG(ERROR) << "Failed to create socket";
    return;
  }

  pid_t child = fork();
  if (child == -1) {
    PLOG(ERROR) << "Failed to fork child process";
    return;
  }
  if (child == 0) {
    recovery_socket.reset();
    execl("/system/bin/minadbd", "minadbd", "--socket_fd",
          std::to_string(minadbd_socket.release()).c_str(), nullptr);

    _exit(EXIT_FAILURE);
  }

  minadbd_socket.reset();

  // We need to call SetUsbConfig() after forking minadbd service. Because the function waits for
  // the usb state to be updated, which depends on sys.usb.ffs.ready=1 set in the adb daemon.
  if (!SetUsbConfig("sideload")) {
    LOG(ERROR) << "Failed to set usb config to sideload";
    return;
  }

  std::thread listener_thread(ListenAndExecuteMinadbdCommands, child, std::move(recovery_socket),
                              std::ref(command_map));

  if (listener_thread.joinable()) {
    listener_thread.join();
  }

  int status;
  waitpid(child, &status, 0);
  if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
    if (WEXITSTATUS(status) == MinadbdErrorCode::kMinadbdAdbVersionError) {
      LOG(ERROR) << "\nYou need adb 1.0.32 or newer to sideload\nto this device.\n";
    } else if (!WIFSIGNALED(status)) {
      LOG(ERROR) << "\n(adbd status " << WEXITSTATUS(status) << ")";
    }
  }

  signal(SIGPIPE, SIG_DFL);
}

int apply_from_adb(RecoveryUI* ui) {
  // Save the usb state to restore after the sideload operation.
  std::string usb_state = android::base::GetProperty("sys.usb.state", "none");
  // Clean up state and stop adbd.
  if (usb_state != "none" && !SetUsbConfig("none")) {
    LOG(ERROR) << "Failed to clear USB config";
    return INSTALL_ERROR;
  }

  ui->Print(
      "\n\nNow send the package you want to apply\n"
      "to the device with \"adb sideload <filename>\"...\n");

  int install_result = INSTALL_ERROR;
  std::map<MinadbdCommands, CommandFunction> command_map{
    { MinadbdCommands::kInstall, std::bind(&AdbInstallPackageHandler, ui, &install_result) },
  };

  CreateMinadbdServiceAndExecuteCommands(command_map);

  // Clean up before switching to the older state, for example setting the state
  // to none sets sys/class/android_usb/android0/enable to 0.
  if (!SetUsbConfig("none")) {
    LOG(ERROR) << "Failed to clear USB config";
  }

  if (usb_state != "none") {
    if (!SetUsbConfig(usb_state)) {
      LOG(ERROR) << "Failed to set USB config to " << usb_state;
    }
  }

  return install_result;
}