/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "PosixSerialPlatformService.h"

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>

#include "SerialLogging.h"
#include "nsDirectoryServiceDefs.h"
#include "nsIFile.h"
#include "nsString.h"
#include "nsThreadUtils.h"

#ifdef XP_MACOSX
#  include <CoreFoundation/CFNumber.h>
#  include <IOKit/IOKitLib.h>
#  include <IOKit/serial/IOSerialKeys.h>
#  include <IOKit/serial/ioss.h>
#  include <IOKit/usb/IOUSBLib.h>
#  ifndef kIOMainPortDefault
#    define kIOMainPortDefault kIOMasterPortDefault
#  endif
#endif

#ifdef TCGETS2
// Support non-standard baud rates through TCGETS2/TCSETS2
#  define LINUX_NSTD_BAUD 1
#endif

#ifdef LINUX_NSTD_BAUD
#  include <asm/termbits.h>
#else
#  include <termios.h>
#endif

#ifdef XP_LINUX
#  include <linux/serial.h>
#endif

namespace mozilla::dom {

constexpr int kMaxReadBufferSize = 4096;
constexpr int kPollTimeoutMs = 100;
// Maximum total time to spend in a single Write() call before giving up.
// Prevents indefinite blocking when a serial port's buffer is full (e.g.
// due to flow control), which would block all other serial ports.
constexpr int kWriteTimeoutMs = 5000;
#ifdef XP_MACOSX
constexpr size_t kDeviceNameBufferSize = 256;
#endif

// Returns true if aDevpath refers to a real serial device by attempting
// to open it and issuing a TIOCMGET ioctl. This filters out phantom ttyS*
// entries and non-serial tty devices.
static bool IsRealSerialPort(const char* aDevpath) {
  int fd = open(aDevpath, O_RDWR | O_NONBLOCK | O_NOCTTY);
  if (fd < 0) {
    return false;
  }
  int status;
  bool isReal = ioctl(fd, TIOCMGET, &status) == 0;
  close(fd);
  return isReal;
}

PosixSerialPlatformService::PosixSerialPlatformService()
#ifdef XP_LINUX
    : mMonitor(nullptr),
      mMonitorSourceID(0)
#elif defined(XP_MACOSX)
    : mNotificationPort(nullptr),
      mAddedIterator(0),
      mRemovedIterator(0)
#endif
{
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p] created", this));
}

PosixSerialPlatformService::~PosixSerialPlatformService() {
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p] destroyed", this));
}

nsresult PosixSerialPlatformService::Init() { return StartMonitoring(); }

void PosixSerialPlatformService::Shutdown() {
  if (IsShutdown()) {
    return;
  }
  MOZ_LOG(gWebSerialLog, LogLevel::Info,
          ("PosixSerialPlatformService[%p]::Shutdown (closing %u open ports)",
           this, mOpenPorts.Count()));
  StopMonitoring();
  mOpenPorts.Clear();
  SerialPlatformService::Shutdown();
}

nsresult PosixSerialPlatformService::EnumeratePortsImpl(
    SerialPortList& aPorts) {
  aPorts.Clear();

  MOZ_LOG(
      gWebSerialLog, LogLevel::Debug,
      ("PosixSerialPlatformService[%p]::EnumeratePorts starting enumeration",
       this));

#ifdef XP_MACOSX
  io_iterator_t serialPortIterator;
  CFMutableDictionaryRef classesToMatch =
      IOServiceMatching(kIOSerialBSDServiceValue);

  if (classesToMatch == nullptr) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::EnumeratePorts IOServiceMatching "
             "failed",
             this));
    return NS_ERROR_FAILURE;
  }

  // The call to IOServiceGetMatchingServices consumes a ref to classesToMatch.
  if (IOServiceGetMatchingServices(kIOMainPortDefault, classesToMatch,
                                   &serialPortIterator) != KERN_SUCCESS) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::EnumeratePorts "
             "IOServiceGetMatchingServices failed",
             this));
    return NS_ERROR_FAILURE;
  }

  io_object_t serialService;
  while ((serialService = IOIteratorNext(serialPortIterator))) {
    IPCSerialPortInfo info;
    if (ExtractDeviceInfo(serialService, info)) {
      MOZ_LOG(gWebSerialLog, LogLevel::Debug,
              ("PosixSerialPlatformService[%p]::EnumeratePorts found port: "
               "path=%s, friendlyName=%s, VID=0x%04x, PID=0x%04x",
               this, NS_ConvertUTF16toUTF8(info.path()).get(),
               NS_ConvertUTF16toUTF8(info.friendlyName()).get(),
               info.usbVendorId().valueOr(0), info.usbProductId().valueOr(0)));

      aPorts.AppendElement(info);
    }

    IOObjectRelease(serialService);
  }

  IOObjectRelease(serialPortIterator);

#elif defined(XP_LINUX)
  // Use an IIFE to avoid excessive nesting
  [&]() {
    if (!mUdevLib) {
      MOZ_LOG(gWebSerialLog, LogLevel::Warning,
              ("PosixSerialPlatformService[%p]::EnumeratePorts udev not "
               "available, falling back to /dev scan",
               this));
      return;
    }

    udev_enumerate* enumerate = mUdevLib->udev_enumerate_new(mUdevLib->udev);
    if (!enumerate) {
      MOZ_LOG(gWebSerialLog, LogLevel::Error,
              ("PosixSerialPlatformService[%p]::EnumeratePorts "
               "udev_enumerate_new failed",
               this));
      return;
    }
    auto cleanupEnum =
        MakeScopeExit([&]() { mUdevLib->udev_enumerate_unref(enumerate); });

    if (mUdevLib->udev_enumerate_add_match_subsystem(enumerate, "tty") < 0 ||
        mUdevLib->udev_enumerate_scan_devices(enumerate) < 0) {
      MOZ_LOG(gWebSerialLog, LogLevel::Error,
              ("PosixSerialPlatformService[%p]::EnumeratePorts "
               "udev enumerate setup failed",
               this));
      return;
    }

    for (udev_list_entry* entry =
             mUdevLib->udev_enumerate_get_list_entry(enumerate);
         entry; entry = mUdevLib->udev_list_entry_get_next(entry)) {
      const char* syspath = mUdevLib->udev_list_entry_get_name(entry);
      if (!syspath) {
        MOZ_LOG(gWebSerialLog, LogLevel::Warning,
                ("PosixSerialPlatformService[%p]::EnumeratePorts "
                 "udev_list_entry_get_name returned null",
                 this));
        continue;
      }

      MOZ_LOG(gWebSerialLog, LogLevel::Debug,
              ("PosixSerialPlatformService[%p]::EnumeratePorts examining "
               "syspath=%s",
               this, syspath));

      udev_device* dev =
          mUdevLib->udev_device_new_from_syspath(mUdevLib->udev, syspath);
      if (!dev) {
        MOZ_LOG(gWebSerialLog, LogLevel::Warning,
                ("PosixSerialPlatformService[%p]::EnumeratePorts "
                 "udev_device_new_from_syspath failed for %s",
                 this, syspath));
        continue;
      }
      auto cleanupDev =
          MakeScopeExit([&]() { mUdevLib->udev_device_unref(dev); });

      const char* devnode = mUdevLib->udev_device_get_devnode(dev);
      if (!devnode) {
        MOZ_LOG(gWebSerialLog, LogLevel::Debug,
                ("PosixSerialPlatformService[%p]::EnumeratePorts "
                 "no devnode for syspath=%s",
                 this, syspath));
        continue;
      }

      if (!IsRealSerialPort(devnode)) {
        MOZ_LOG(gWebSerialLog, LogLevel::Debug,
                ("PosixSerialPlatformService[%p]::EnumeratePorts "
                 "rejecting device devnode=%s (not a real serial port)",
                 this, devnode));
        continue;
      }

      IPCSerialPortInfo info;
      PopulatePortInfoFromUdev(dev, devnode, info);

      MOZ_LOG(gWebSerialLog, LogLevel::Debug,
              ("PosixSerialPlatformService[%p]::EnumeratePorts found port: "
               "path=%s, friendlyName=%s, VID=0x%04x, PID=0x%04x",
               this, NS_ConvertUTF16toUTF8(info.path()).get(),
               NS_ConvertUTF16toUTF8(info.friendlyName()).get(),
               info.usbVendorId().valueOr(0), info.usbProductId().valueOr(0)));

      aPorts.AppendElement(info);
    }
  }();

  // Also scan /dev/ directly for onboard serial ports that may not appear
  // in the udev enumeration (e.g. on minimal or embedded Linux systems).
  DIR* devDir = opendir("/dev");
  if (devDir) {
    auto cleanupDir = MakeScopeExit([&]() { closedir(devDir); });

    while (struct dirent* ent = readdir(devDir)) {
      nsAutoCString devpath("/dev/");
      devpath.Append(ent->d_name);

      // Skip if already found by udev enumeration.
      NS_ConvertUTF8toUTF16 devpathUtf16(devpath);
      bool alreadyFound = false;
      for (const auto& existing : aPorts) {
        if (existing.path() == devpathUtf16) {
          alreadyFound = true;
          break;
        }
      }
      if (alreadyFound) {
        continue;
      }

      if (!IsRealSerialPort(devpath.get())) {
        continue;
      }

      MOZ_LOG(gWebSerialLog, LogLevel::Debug,
              ("PosixSerialPlatformService[%p]::EnumeratePorts found onboard "
               "port from /dev scan: %s",
               this, devpath.get()));

      IPCSerialPortInfo info;
      bool haveSetInfo = false;
      // Try udev lookup for richer metadata (product name, vendor/product IDs).
      nsAutoCString syspath("/sys/class/tty/");
      syspath.Append(ent->d_name);
      udev_device* dev = mUdevLib ? mUdevLib->udev_device_new_from_syspath(
                                        mUdevLib->udev, syspath.get())
                                  : nullptr;
      if (dev) {
        PopulatePortInfoFromUdev(dev, devpath.get(), info);
        mUdevLib->udev_device_unref(dev);
        haveSetInfo = true;
      }
      if (!haveSetInfo) {
        info.id() = devpathUtf16;
        info.path() = devpathUtf16;
        info.friendlyName() =
            NS_ConvertUTF8toUTF16(nsDependentCString(ent->d_name));
      }
      aPorts.AppendElement(info);
    }
  }
#endif

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::EnumeratePorts found %zu ports",
           this, aPorts.Length()));

  return NS_OK;
}

int PosixSerialPlatformService::FindPortFd(const nsString& aPortId) {
  AssertIsOnIOThread();
  if (auto entry = mOpenPorts.Lookup(aPortId)) {
    return entry.Data().get();
  }
  return -1;
}

// Returns whether the conversion succeeded
static bool ConvertBaudRate(uint32_t aBaudRate, speed_t& aSpeed) {
#define BAUDRATE_TO_SPEED_CASE(x) \
  case x:                         \
    aSpeed = B##x;                \
    return true;

  switch (aBaudRate) {
    BAUDRATE_TO_SPEED_CASE(0)
    BAUDRATE_TO_SPEED_CASE(50)
    BAUDRATE_TO_SPEED_CASE(75)
    BAUDRATE_TO_SPEED_CASE(110)
    BAUDRATE_TO_SPEED_CASE(134)
    BAUDRATE_TO_SPEED_CASE(150)
    BAUDRATE_TO_SPEED_CASE(200)
    BAUDRATE_TO_SPEED_CASE(300)
    BAUDRATE_TO_SPEED_CASE(600)
    BAUDRATE_TO_SPEED_CASE(1200)
    BAUDRATE_TO_SPEED_CASE(1800)
    BAUDRATE_TO_SPEED_CASE(2400)
    BAUDRATE_TO_SPEED_CASE(4800)
    BAUDRATE_TO_SPEED_CASE(9600)
    BAUDRATE_TO_SPEED_CASE(19200)
    BAUDRATE_TO_SPEED_CASE(38400)
    BAUDRATE_TO_SPEED_CASE(57600)
    BAUDRATE_TO_SPEED_CASE(115200)
#ifdef B230400
    BAUDRATE_TO_SPEED_CASE(230400)
#endif
#ifdef B460800
    BAUDRATE_TO_SPEED_CASE(460800)
#endif
#ifdef B576000
    BAUDRATE_TO_SPEED_CASE(576000)
#endif
#ifdef B921600
    BAUDRATE_TO_SPEED_CASE(921600)
#endif
  }
#undef BAUDRATE_TO_SPEED_CASE

  return false;
}

nsresult PosixSerialPlatformService::ConfigurePort(
    int aFd, const IPCSerialOptions& aOptions) {
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::ConfigurePort fd=%d, baudRate=%u, "
           "dataBits=%u, stopBits=%u, parity=%u, flowControl=%u",
           this, aFd, aOptions.baudRate(), aOptions.dataBits(),
           aOptions.stopBits(), static_cast<uint8_t>(aOptions.parity()),
           static_cast<uint8_t>(aOptions.flowControl())));

#ifdef LINUX_NSTD_BAUD
  struct termios2 tty;
  if (ioctl(aFd, TCGETS2, &tty) < 0) {
#else
  struct termios tty;
  if (tcgetattr(aFd, &tty) != 0) {
#endif
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::ConfigurePort tcgetattr/ioctl "
             "failed: "
             "errno=%d",
             this, errno));
    return NS_ERROR_FAILURE;
  }

  tty.c_cflag |= (CLOCAL | CREAD);
  tty.c_cflag &= ~HUPCL;

  tty.c_cflag &= ~CSIZE;
  switch (aOptions.dataBits()) {
    case 7:
      tty.c_cflag |= CS7;
      break;
    case 8:
      tty.c_cflag |= CS8;
      break;
    default:
      MOZ_LOG(
          gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::ConfigurePort invalid dataBits: %u",
           this, aOptions.dataBits()));
      return NS_ERROR_INVALID_ARG;
  }

  switch (aOptions.stopBits()) {
    case 1:
      tty.c_cflag &= ~CSTOPB;
      break;
    case 2:
      tty.c_cflag |= CSTOPB;
      break;
    default:
      MOZ_LOG(
          gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::ConfigurePort invalid stopBits: %u",
           this, aOptions.stopBits()));
      return NS_ERROR_INVALID_ARG;
  }

  switch (aOptions.parity()) {
    case ParityType::None:
      tty.c_cflag &= ~PARENB;
      tty.c_iflag |= IGNPAR;
      tty.c_iflag &= ~INPCK;
      break;
    case ParityType::Even:
      tty.c_cflag |= PARENB;
      tty.c_cflag &= ~PARODD;
      tty.c_iflag &= ~IGNPAR;
      tty.c_iflag |= INPCK;
      break;
    case ParityType::Odd:
      tty.c_cflag |= (PARENB | PARODD);
      tty.c_iflag &= ~IGNPAR;
      tty.c_iflag |= INPCK;
      break;
  }

  switch (aOptions.flowControl()) {
    case FlowControlType::None:
      tty.c_cflag &= ~CRTSCTS;
      break;
    case FlowControlType::Hardware:
      tty.c_cflag |= CRTSCTS;
      break;
  }

  // Set flags for raw operation
  tty.c_lflag &= ~(ICANON | ECHO | ECHOE | ECHONL | ISIG | IEXTEN);
  tty.c_oflag &= ~OPOST;
  tty.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | ICRNL | IXON |
                   IXOFF | IXANY);
  tty.c_iflag |= PARMRK;

  tty.c_cc[VMIN] = 0;
  tty.c_cc[VTIME] = 0;

  speed_t speed;
#if defined(XP_MACOSX)
  // The IOSSIOSPEED ioctl() is only available on Mac.
  bool need_speedioctl = false;
#endif
  if (ConvertBaudRate(aOptions.baudRate(), speed)) {
#ifdef XP_LINUX
    tty.c_cflag &= ~CBAUD;
    tty.c_cflag |= speed;
#else
    if (cfsetispeed(&tty, speed) != 0) {
      MOZ_LOG(
          gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::ConfigurePort cfsetispeed failed: "
           "errno=%d",
           this, errno));
      return NS_ERROR_FAILURE;
    }
    if (cfsetospeed(&tty, speed) != 0) {
      MOZ_LOG(
          gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::ConfigurePort cfsetospeed failed: "
           "errno=%d",
           this, errno));
      return NS_ERROR_FAILURE;
    }
#endif
  } else {
    // Attempt to use a custom baud rate
    MOZ_LOG(gWebSerialLog, LogLevel::Verbose,
            ("PosixSerialPlatformService[%p]::ConfigurePort attempting to use "
             "custom baudRate: %u",
             this, aOptions.baudRate()));
#ifdef LINUX_NSTD_BAUD
    tty.c_cflag &= ~CBAUD;
    tty.c_cflag |= CBAUDEX;
    tty.c_ispeed = aOptions.baudRate();
    tty.c_ospeed = aOptions.baudRate();
#elif defined(XP_MACOSX)
    // cfsetispeed() and cfsetospeed() sometimes work for custom baud rates
    // on Mac, but the ioctl is more reliable. But we have to set it after
    // setting everything else or it will get overwritten.
    need_speedioctl = true;
#else
  // User requested a custom baud rate but we don't have TCSETS2 or
  // IOSSIOSPEED ioctl's, so there's nothing we can do.
  MOZ_LOG(gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::ConfigurePort could not set "
           "custom baudRate: %u",
           this, aOptions.baudRate()));
  return NS_ERROR_FAILURE;
#endif
  }
#ifdef LINUX_NSTD_BAUD
  if (ioctl(aFd, TCSETS2, &tty) < 0) {
#else
  if (tcsetattr(aFd, TCSANOW, &tty) != 0) {
#endif
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::ConfigurePort tcsetattr/ioctl "
             "failed: "
             "errno=%d",
             this, errno));
    return NS_ERROR_FAILURE;
  }

#if defined(XP_MACOSX)
  if (need_speedioctl) {
    speed = aOptions.baudRate();
    if (ioctl(aFd, IOSSIOSPEED, &speed) == -1) {
      MOZ_LOG(gWebSerialLog, LogLevel::Error,
              ("PosixSerialPlatformService[%p]::ConfigurePort IOSSIOSPEED "
               "ioctl failed to set baudRate %u: "
               "errno=%d",
               this, aOptions.baudRate(), errno));
      return NS_ERROR_FAILURE;
    }
  }
#endif

  MOZ_LOG(
      gWebSerialLog, LogLevel::Debug,
      ("PosixSerialPlatformService[%p]::ConfigurePort configuration successful",
       this));
  return NS_OK;
}

nsresult PosixSerialPlatformService::OpenImpl(
    const nsString& aPortId, const IPCSerialOptions& aOptions) {
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Open portId=%s, baudRate=%u", this,
           NS_ConvertUTF16toUTF8(aPortId).get(), aOptions.baudRate()));
  AssertIsOnIOThread();

  // Reject path traversal attempts (e.g. "/dev/tty/../../../etc/passwd").
  if (aPortId.Find(u"/.."_ns) != kNotFound) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Open rejected portId '%s': "
             "path traversal detected",
             this, NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_INVALID_ARG;
  }

  // Validate portId is a serial device path. This prevents a compromised
  // content process from using a crafted portId to open arbitrary files.
  if (!IsRealSerialPort(NS_ConvertUTF16toUTF8(aPortId).get())) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Open rejected invalid portId "
             "'%s': not a serial device path",
             this, NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_INVALID_ARG;
  }

  if (mOpenPorts.Contains(aPortId)) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Open port already open: %s", this,
             NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_FILE_IS_LOCKED;
  }

  NS_ConvertUTF16toUTF8 path(aPortId);
  int fd = open(path.get(), O_RDWR | O_NOCTTY | O_NONBLOCK);

  if (fd < 0) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::Open open() failed for %s: errno=%d",
         this, path.get(), errno));
    if (errno == EACCES) {
      return NS_ERROR_FILE_ACCESS_DENIED;
    } else if (errno == ENOENT) {
      return NS_ERROR_FILE_NOT_FOUND;
    } else if (errno == EBUSY) {
      return NS_ERROR_FILE_IS_LOCKED;
    } else {
      return NS_ERROR_NOT_AVAILABLE;
    }
  }

  mozilla::UniqueFileHandle handle(fd);
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Open opened fd=%d", this, fd));

  if (ioctl(fd, TIOCEXCL) < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Warning,
            ("PosixSerialPlatformService[%p]::Open TIOCEXCL failed: errno=%d",
             this, errno));
  }

  nsresult rv = ConfigurePort(fd, aOptions);
  if (NS_FAILED(rv)) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::Open ConfigurePort failed: 0x%08x",
         this, static_cast<uint32_t>(rv)));
    return rv;
  }

#ifdef LINUX_NSTD_BAUD
  ioctl(fd, TCFLSH, TCIOFLUSH);
#else
  tcflush(fd, TCIOFLUSH);
#endif

  mOpenPorts.InsertOrUpdate(aPortId, std::move(handle));
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Open successfully opened port %s",
           this, NS_ConvertUTF16toUTF8(aPortId).get()));
  return NS_OK;
}

nsresult PosixSerialPlatformService::CloseImpl(const nsString& aPortId) {
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Close portId=%s", this,
           NS_ConvertUTF16toUTF8(aPortId).get()));
  AssertIsOnIOThread();

  if (!mOpenPorts.Remove(aPortId)) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Close port not found: %s", this,
             NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Close successfully closed port %s",
           this, NS_ConvertUTF16toUTF8(aPortId).get()));
  return NS_OK;
}

nsresult PosixSerialPlatformService::ReadImpl(const nsString& aPortId,
                                              Span<uint8_t> aBuf,
                                              uint32_t& aBytesRead) {
  int fd = FindPortFd(aPortId);
  if (fd < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Read port not found: %s", this,
             NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  int bytesAvailable = 0;
  if (ioctl(fd, FIONREAD, &bytesAvailable) < 0) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::Read ioctl FIONREAD failed: errno=%d",
         this, errno));
    return NS_ERROR_FAILURE;
  }

  if (bytesAvailable == 0) {
    return NS_OK;
  }

  int bytesToRead = std::min<int>(
      {bytesAvailable, kMaxReadBufferSize, static_cast<int>(aBuf.Length())});

  ssize_t bytesRead = read(fd, aBuf.Elements(), bytesToRead);

  if (bytesRead < 0) {
    if (errno == EAGAIN) {
      MOZ_LOG(
          gWebSerialLog, LogLevel::Verbose,
          ("PosixSerialPlatformService[%p]::Read would block, no data", this));
      return NS_OK;
    }
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Read read() failed: errno=%d",
             this, errno));
    return NS_ERROR_FAILURE;
  }

  aBytesRead = static_cast<uint32_t>(bytesRead);
  MOZ_LOG(
      gWebSerialLog, LogLevel::Verbose,
      ("PosixSerialPlatformService[%p]::Read read %zd bytes", this, bytesRead));
  return NS_OK;
}

nsresult PosixSerialPlatformService::WriteImpl(const nsString& aPortId,
                                               Span<const uint8_t> aData) {
  int fd = FindPortFd(aPortId);
  if (fd < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Write port not found: %s", this,
             NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  if (aData.IsEmpty()) {
    MOZ_LOG(gWebSerialLog, LogLevel::Verbose,
            ("PosixSerialPlatformService[%p]::Write empty data", this));
    return NS_OK;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Verbose,
          ("PosixSerialPlatformService[%p]::Write writing %zu bytes", this,
           aData.Length()));

  size_t totalWritten = 0;
  const uint8_t* buffer = aData.Elements();
  size_t remaining = aData.Length();
  int totalPollTimeMs = 0;

  while (remaining > 0) {
    ssize_t bytesWritten = write(fd, buffer + totalWritten, remaining);

    if (bytesWritten < 0) {
      if (errno == EINTR) {
        continue;
      }
      if (errno == EAGAIN) {
        if (totalPollTimeMs >= kWriteTimeoutMs) {
          MOZ_LOG(gWebSerialLog, LogLevel::Error,
                  ("PosixSerialPlatformService[%p]::Write timed out after %dms "
                   "with %zu bytes remaining",
                   this, totalPollTimeMs, remaining));
          return NS_ERROR_NET_TIMEOUT;
        }

        struct pollfd pfd;
        pfd.fd = fd;
        pfd.events = POLLOUT;
        pfd.revents = 0;

        int pollResult = poll(&pfd, 1, kPollTimeoutMs);
        if (pollResult < 0) {
          if (errno == EINTR) {
            continue;
          }
          MOZ_LOG(
              gWebSerialLog, LogLevel::Error,
              ("PosixSerialPlatformService[%p]::Write poll failed: errno=%d",
               this, errno));
          return NS_ERROR_FAILURE;
        }
        if (pollResult == 0) {
          totalPollTimeMs += kPollTimeoutMs;
          continue;
        }
        if (pfd.revents & (POLLERR | POLLHUP | POLLNVAL)) {
          MOZ_LOG(gWebSerialLog, LogLevel::Error,
                  ("PosixSerialPlatformService[%p]::Write poll error: "
                   "revents=0x%x",
                   this, pfd.revents));
          return NS_ERROR_FAILURE;
        }
        continue;
      }
      MOZ_LOG(gWebSerialLog, LogLevel::Error,
              ("PosixSerialPlatformService[%p]::Write write() failed: errno=%d",
               this, errno));
      return NS_ERROR_FAILURE;
    }

    if (bytesWritten == 0) {
      MOZ_LOG(
          gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::Write write() returned 0", this));
      return NS_ERROR_FAILURE;
    }

    totalWritten += bytesWritten;
    remaining -= bytesWritten;
    totalPollTimeMs = 0;

    if (remaining > 0) {
      MOZ_LOG(gWebSerialLog, LogLevel::Verbose,
              ("PosixSerialPlatformService[%p]::Write partial write: %zd "
               "bytes, %zu "
               "remaining",
               this, bytesWritten, remaining));
    }
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Verbose,
          ("PosixSerialPlatformService[%p]::Write successfully wrote %zu bytes",
           this, totalWritten));
  return NS_OK;
}

nsresult PosixSerialPlatformService::DrainImpl(const nsString& aPortId) {
  int fd = FindPortFd(aPortId);
  if (fd < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Drain port not found: %s", this,
             NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Drain draining transmit buffers",
           this));

#ifdef LINUX_NSTD_BAUD
  if (ioctl(fd, TCSBRK, 1) < 0) {
#else
  if (tcdrain(fd) < 0) {
#endif
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Drain tcdrain() failed: errno=%d",
             this, errno));
    return NS_ERROR_FAILURE;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Drain successfully drained buffers",
           this));
  return NS_OK;
}

nsresult PosixSerialPlatformService::FlushImpl(const nsString& aPortId,
                                               bool aReceive) {
  int fd = FindPortFd(aPortId);
  if (fd < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Flush port not found: %s", this,
             NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  int queue = aReceive ? TCIFLUSH : TCOFLUSH;
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Flush discarding %s buffers", this,
           aReceive ? "receive" : "transmit"));

#ifdef LINUX_NSTD_BAUD
  if (ioctl(fd, TCFLSH, queue) < 0) {
#else
  if (tcflush(fd, queue) < 0) {
#endif
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::Flush tcflush() failed: errno=%d",
             this, errno));
    return NS_ERROR_FAILURE;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::Flush successfully flushed %s "
           "buffers",
           this, aReceive ? "receive" : "transmit"));
  return NS_OK;
}

nsresult PosixSerialPlatformService::SetSignalsImpl(
    const nsString& aPortId, const IPCSerialOutputSignals& aSignals) {
  MOZ_LOG(
      gWebSerialLog, LogLevel::Debug,
      ("PosixSerialPlatformService[%p]::SetSignals portId=%s, DTR=%s, RTS=%s, "
       "Break=%s",
       this, NS_ConvertUTF16toUTF8(aPortId).get(),
       aSignals.dataTerminalReady().isSome()
           ? (aSignals.dataTerminalReady().value() ? "true" : "false")
           : "unchanged",
       aSignals.requestToSend().isSome()
           ? (aSignals.requestToSend().value() ? "true" : "false")
           : "unchanged",
       aSignals.breakSignal().isSome()
           ? (aSignals.breakSignal().value() ? "true" : "false")
           : "unchanged"));

  int fd = FindPortFd(aPortId);
  if (fd < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::SetSignals port not found: %s",
             this, NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  if (aSignals.dataTerminalReady().isSome() ||
      aSignals.requestToSend().isSome()) {
    int status;
    if (ioctl(fd, TIOCMGET, &status) < 0) {
      MOZ_LOG(gWebSerialLog, LogLevel::Error,
              ("PosixSerialPlatformService[%p]::SetSignals failure to get "
               "status on %d: errno=%d",
               this, fd, errno));
      return NS_ERROR_FAILURE;
    }
    MOZ_LOG(gWebSerialLog, LogLevel::Verbose,
            ("PosixSerialPlatformService[%p]::SetSignals got status on %d: "
             "status=0x%x",
             this, fd, uint32_t(status)));

    // The spec requires that we set DTR first, then RTS, then break.
    // We could do this with TIOCMBIS or TIOCMBIC to set or clear
    // individual flags, but that seemed to return ENOTTY on Mac.
    // So instead we somewhat clunkily get the current flags, toggle
    // the bit, then set the flags for each thing we want to change.
    if (aSignals.dataTerminalReady().isSome()) {
      if (aSignals.dataTerminalReady().value()) {
        status |= TIOCM_DTR;
      } else {
        status &= ~TIOCM_DTR;
      }
      if (ioctl(fd, TIOCMSET, &status) < 0) {
        MOZ_LOG(gWebSerialLog, LogLevel::Error,
                ("PosixSerialPlatformService[%p]::SetSignals set DTR status on "
                 "%d failed: "
                 "newStatus=%x errno=%d",
                 this, fd, uint32_t(status), errno));
        return NS_ERROR_FAILURE;
      }
    }

    if (aSignals.requestToSend().isSome()) {
      if (aSignals.requestToSend().value()) {
        status |= TIOCM_RTS;
      } else {
        status &= ~TIOCM_RTS;
      }
      if (ioctl(fd, TIOCMSET, &status) < 0) {
        MOZ_LOG(gWebSerialLog, LogLevel::Error,
                ("PosixSerialPlatformService[%p]::SetSignals set RTS status on "
                 "%d failed: "
                 "newStatus=%x errno=%d",
                 this, fd, uint32_t(status), errno));
        return NS_ERROR_FAILURE;
      }
    }
  }

  if (aSignals.breakSignal().isSome()) {
    int cmd = aSignals.breakSignal().value() ? TIOCSBRK : TIOCCBRK;
    if (ioctl(fd, cmd) < 0) {
      MOZ_LOG(
          gWebSerialLog, LogLevel::Error,
          ("PosixSerialPlatformService[%p]::SetSignals ioctl %s on %d failed: "
           "errno=%d",
           this, aSignals.breakSignal().value() ? "TIOCSBRK" : "TIOCCBRK", fd,
           errno));
      return NS_ERROR_FAILURE;
    }
  }

  MOZ_LOG(
      gWebSerialLog, LogLevel::Debug,
      ("PosixSerialPlatformService[%p]::SetSignals signals set successfully",
       this));
  return NS_OK;
}

nsresult PosixSerialPlatformService::GetSignalsImpl(
    const nsString& aPortId, IPCSerialInputSignals& aSignals) {
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::GetSignals portId=%s", this,
           NS_ConvertUTF16toUTF8(aPortId).get()));

  int fd = FindPortFd(aPortId);
  if (fd < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::GetSignals port not found: %s",
             this, NS_ConvertUTF16toUTF8(aPortId).get()));
    return NS_ERROR_NOT_AVAILABLE;
  }

  int status;
  if (ioctl(fd, TIOCMGET, &status) < 0) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::GetSignals ioctl TIOCMGET failed: "
         "errno=%d",
         this, errno));
    return NS_ERROR_FAILURE;
  }

  aSignals = IPCSerialInputSignals{
      (status & TIOCM_CAR) != 0,  // dataCarrierDetect
      (status & TIOCM_CTS) != 0,  // clearToSend
      (status & TIOCM_RNG) != 0,  // ringIndicator
      (status & TIOCM_DSR) != 0   // dataSetReady
  };

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::GetSignals DCD=%d, CTS=%d, RI=%d, "
           "DSR=%d",
           this, aSignals.dataCarrierDetect(), aSignals.clearToSend(),
           aSignals.ringIndicator(), aSignals.dataSetReady()));

  return NS_OK;
}

nsresult PosixSerialPlatformService::StartMonitoring() {
#ifdef XP_LINUX
  return InitializeUdev();
#elif defined(XP_MACOSX)
  return InitializeMacOS();
#else
  return NS_OK;
#endif
}

#ifdef XP_MACOSX
nsresult PosixSerialPlatformService::InitializeMacOS() {
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::InitializeMacOS setting up IOKit "
           "notifications",
           this));

  mNotificationPort = IONotificationPortCreate(kIOMainPortDefault);
  if (!mNotificationPort) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeMacOS "
             "IONotificationPortCreate failed",
             this));
    return NS_ERROR_FAILURE;
  }

  CFRunLoopAddSource(CFRunLoopGetMain(),
                     IONotificationPortGetRunLoopSource(mNotificationPort),
                     kCFRunLoopDefaultMode);
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::InitializeMacOS added run loop "
           "source to main run loop",
           this));

  CFMutableDictionaryRef matchingDict =
      IOServiceMatching(kIOSerialBSDServiceValue);
  if (!matchingDict) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::InitializeMacOS IOServiceMatching "
         "failed",
         this));
    return NS_ERROR_FAILURE;
  }

  // The call to IOServiceAddMatchingNotification consumes a ref to
  // matchingDict.
  kern_return_t kr = IOServiceAddMatchingNotification(
      mNotificationPort, kIOMatchedNotification, matchingDict,
      DeviceAddedCallback, this, &mAddedIterator);
  if (kr != KERN_SUCCESS) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeMacOS "
             "IOServiceAddMatchingNotification for added devices failed: %d",
             this, kr));
    return NS_ERROR_FAILURE;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::InitializeMacOS draining initial "
           "added device iterator",
           this));
  OnDeviceAdded(mAddedIterator, true);

  // The call to IOServiceAddMatchingNotification consumes a ref to
  // matchingDict2.
  CFMutableDictionaryRef matchingDict2 =
      IOServiceMatching(kIOSerialBSDServiceValue);
  if (!matchingDict2) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::InitializeMacOS IOServiceMatching "
         "failed for removed devices",
         this));
    return NS_ERROR_FAILURE;
  }

  kr = IOServiceAddMatchingNotification(
      mNotificationPort, kIOTerminatedNotification, matchingDict2,
      DeviceRemovedCallback, this, &mRemovedIterator);
  if (kr != KERN_SUCCESS) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeMacOS "
             "IOServiceAddMatchingNotification for removed devices failed: %d",
             this, kr));
    return NS_ERROR_FAILURE;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::InitializeMacOS draining initial "
           "removed device iterator",
           this));
  OnDeviceRemoved(mRemovedIterator, true);

  MOZ_LOG(gWebSerialLog, LogLevel::Info,
          ("PosixSerialPlatformService[%p]::InitializeMacOS monitoring started",
           this));
  return NS_OK;
}
#endif

void PosixSerialPlatformService::StopMonitoring() {
#ifdef XP_LINUX
  ShutdownUdev();
#elif defined(XP_MACOSX)
  if (mAddedIterator) {
    IOObjectRelease(mAddedIterator);
    mAddedIterator = 0;
  }

  if (mRemovedIterator) {
    IOObjectRelease(mRemovedIterator);
    mRemovedIterator = 0;
  }

  if (mNotificationPort) {
    CFRunLoopSourceRef runLoopSource =
        IONotificationPortGetRunLoopSource(mNotificationPort);
    if (runLoopSource) {
      CFRunLoopRemoveSource(CFRunLoopGetMain(), runLoopSource,
                            kCFRunLoopDefaultMode);
      MOZ_LOG(gWebSerialLog, LogLevel::Debug,
              ("PosixSerialPlatformService[%p]::StopMonitoring removed run "
               "loop source from main run loop",
               this));
    }
    IONotificationPortDestroy(mNotificationPort);
    mNotificationPort = nullptr;
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Info,
          ("PosixSerialPlatformService[%p]::StopMonitoring monitoring stopped",
           this));
#endif
}

#ifdef XP_LINUX
nsresult PosixSerialPlatformService::InitializeUdev() {
  mUdevLib = MakeUnique<udev_lib>();
  if (!*mUdevLib) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeUdev udev_lib "
             "initialization failed",
             this));
    mUdevLib = nullptr;
    return NS_ERROR_FAILURE;
  }

  mMonitor = mUdevLib->udev_monitor_new_from_netlink(mUdevLib->udev, "udev");
  if (!mMonitor) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeUdev "
             "udev_monitor_new_from_netlink failed",
             this));
    mUdevLib = nullptr;
    return NS_ERROR_FAILURE;
  }

  auto cleanupUdevAndMonitor = MakeScopeExit([&]() {
    mUdevLib->udev_monitor_unref(mMonitor);
    mMonitor = nullptr;
    mUdevLib = nullptr;
  });

  if (mUdevLib->udev_monitor_filter_add_match_subsystem_devtype(mMonitor, "tty",
                                                                nullptr) < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeUdev filter add failed",
             this));
    return NS_ERROR_FAILURE;
  }

  if (mUdevLib->udev_monitor_enable_receiving(mMonitor) < 0) {
    MOZ_LOG(gWebSerialLog, LogLevel::Error,
            ("PosixSerialPlatformService[%p]::InitializeUdev enable receiving "
             "failed",
             this));
    return NS_ERROR_FAILURE;
  }

  int fd = mUdevLib->udev_monitor_get_fd(mMonitor);
  if (fd < 0) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::InitializeUdev get fd failed", this));
    return NS_ERROR_FAILURE;
  }

  GIOChannel* channel = g_io_channel_unix_new(fd);
  if (!channel) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::InitializeUdev g_io_channel_unix_new "
         "failed",
         this));
    return NS_ERROR_FAILURE;
  }

  // udev operations did not error, so don't clean it up here
  cleanupUdevAndMonitor.release();

  mMonitorSourceID =
      g_io_add_watch(channel, GIOCondition(G_IO_IN | G_IO_ERR | G_IO_HUP),
                     OnUdevMonitor, this);
  g_io_channel_unref(channel);

  MOZ_LOG(gWebSerialLog, LogLevel::Info,
          ("PosixSerialPlatformService[%p]::InitializeUdev udev monitoring "
           "initialized",
           this));
  return NS_OK;
}

void PosixSerialPlatformService::ShutdownUdev() {
  if (mMonitorSourceID) {
    g_source_remove(mMonitorSourceID);
    mMonitorSourceID = 0;
  }

  if (mMonitor && mUdevLib) {
    mUdevLib->udev_monitor_unref(mMonitor);
    mMonitor = nullptr;
  }

  mUdevLib = nullptr;

  MOZ_LOG(gWebSerialLog, LogLevel::Info,
          ("PosixSerialPlatformService[%p]::ShutdownUdev udev monitoring "
           "shutdown",
           this));
}

gboolean PosixSerialPlatformService::OnUdevMonitor(GIOChannel* source,
                                                   GIOCondition condition,
                                                   gpointer data) {
  PosixSerialPlatformService* service =
      static_cast<PosixSerialPlatformService*>(data);

  if (condition & (G_IO_ERR | G_IO_HUP)) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Error,
        ("PosixSerialPlatformService[%p]::OnUdevMonitor error condition: %d",
         service, condition));
    return FALSE;
  }

  if (condition & G_IO_IN) {
    service->ReadUdevChange();
  }

  return TRUE;
}

void PosixSerialPlatformService::PopulatePortInfoFromUdev(
    udev_device* aDev, const char* aDevnode, IPCSerialPortInfo& aPortInfo) {
  MOZ_ASSERT(mUdevLib);

  NS_ConvertUTF8toUTF16 path(aDevnode);
  aPortInfo.id() = path;
  aPortInfo.path() = path;

  const char* productName =
      mUdevLib->udev_device_get_property_value(aDev, "ID_MODEL_FROM_DATABASE");
  if (!productName) {
    productName = mUdevLib->udev_device_get_property_value(aDev, "ID_MODEL");
  }
  if (productName) {
    aPortInfo.friendlyName() = NS_ConvertUTF8toUTF16(productName);
  } else {
    const char* basename = strrchr(aDevnode, '/');
    aPortInfo.friendlyName() =
        NS_ConvertUTF8toUTF16(basename ? basename + 1 : aDevnode);
  }

  const char* vendorIdStr =
      mUdevLib->udev_device_get_property_value(aDev, "ID_VENDOR_ID");
  const char* productIdStr =
      mUdevLib->udev_device_get_property_value(aDev, "ID_MODEL_ID");
  if (vendorIdStr && productIdStr) {
    unsigned int vendorId, productId;
    if (sscanf(vendorIdStr, "%x", &vendorId) == 1 &&
        sscanf(productIdStr, "%x", &productId) == 1) {
      aPortInfo.usbVendorId() = Some(static_cast<uint16_t>(vendorId));
      aPortInfo.usbProductId() = Some(static_cast<uint16_t>(productId));
    }
  }
}

void PosixSerialPlatformService::ReadUdevChange() {
  if (IsShutdown() || !mUdevLib) {
    return;
  }

  udev_device* dev = mUdevLib->udev_monitor_receive_device(mMonitor);
  if (!dev) {
    return;
  }
  auto cleanupDev = MakeScopeExit([&]() { mUdevLib->udev_device_unref(dev); });

  const char* action = mUdevLib->udev_device_get_action(dev);
  const char* devnode = mUdevLib->udev_device_get_devnode(dev);

  if (!action || !devnode) {
    return;
  }

  MOZ_LOG(
      gWebSerialLog, LogLevel::Debug,
      ("PosixSerialPlatformService[%p]::ReadUdevChange action=%s, devnode=%s",
       this, action, devnode));

  if (strcmp(action, "add") == 0) {
    IPCSerialPortInfo portInfo;
    PopulatePortInfoFromUdev(dev, devnode, portInfo);

    MOZ_LOG(
        gWebSerialLog, LogLevel::Info,
        ("PosixSerialPlatformService[%p]::ReadUdevChange device connected: "
         "path=%s, friendlyName=%s, VID=0x%04x, PID=0x%04x",
         this, devnode, NS_ConvertUTF16toUTF8(portInfo.friendlyName()).get(),
         portInfo.usbVendorId().valueOr(0),
         portInfo.usbProductId().valueOr(0)));

    NotifyPortConnected(portInfo);
  } else if (strcmp(action, "remove") == 0) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Info,
        ("PosixSerialPlatformService[%p]::ReadUdevChange device disconnected: "
         "path=%s",
         this, devnode));

    NotifyPortDisconnected(NS_ConvertUTF8toUTF16(devnode));
  }
}
#endif

#ifdef XP_MACOSX
bool PosixSerialPlatformService::ExtractDeviceInfo(
    io_service_t device, IPCSerialPortInfo& portInfo) {
  if (!device) {
    MOZ_LOG(
        gWebSerialLog, LogLevel::Debug,
        ("PosixSerialPlatformService[%p]::ExtractDeviceInfo device is null, "
         "device may be terminated",
         this));
    return false;
  }

  CFTypeRef pathRef = IORegistryEntryCreateCFProperty(
      device, CFSTR(kIODialinDeviceKey), kCFAllocatorDefault, 0);

  auto cleanupPath = MakeScopeExit([&]() {
    if (pathRef) CFRelease(pathRef);
  });

  if (!pathRef) {
    MOZ_LOG(gWebSerialLog, LogLevel::Debug,
            ("PosixSerialPlatformService[%p]::ExtractDeviceInfo failed to get "
             "device path, device may be terminated",
             this));
    return false;
  }

  if (CFGetTypeID(pathRef) != CFStringGetTypeID()) {
    MOZ_LOG(gWebSerialLog, LogLevel::Warning,
            ("PosixSerialPlatformService[%p]::ExtractDeviceInfo device path is "
             "not a string",
             this));
    return false;
  }

  char devicePath[PATH_MAX];
  if (!CFStringGetCString((CFStringRef)pathRef, devicePath, sizeof(devicePath),
                          kCFStringEncodingUTF8)) {
    return false;
  }

  NS_ConvertUTF8toUTF16 path(devicePath);
  portInfo.id() = path;
  portInfo.path() = path;

  CFTypeRef baseNameRef = IORegistryEntryCreateCFProperty(
      device, CFSTR(kIOTTYBaseNameKey), kCFAllocatorDefault, 0);
  auto cleanupBaseName = MakeScopeExit([&]() {
    if (baseNameRef) CFRelease(baseNameRef);
  });

  if (baseNameRef) {
    if (CFGetTypeID(baseNameRef) == CFStringGetTypeID()) {
      char baseName[kDeviceNameBufferSize];
      if (CFStringGetCString((CFStringRef)baseNameRef, baseName,
                             sizeof(baseName), kCFStringEncodingUTF8)) {
        NS_ConvertUTF8toUTF16 friendlyName(baseName);
        portInfo.friendlyName() = friendlyName;
      }
    }
  }

  // We search for these properties on all ancestors, because the registry tree
  // can have a serial service with a USB service as its ancestor.
  CFTypeRef vendorIdRef = IORegistryEntrySearchCFProperty(
      device, kIOServicePlane, CFSTR("idVendor"), kCFAllocatorDefault,
      kIORegistryIterateRecursively | kIORegistryIterateParents);
  CFTypeRef productIdRef = IORegistryEntrySearchCFProperty(
      device, kIOServicePlane, CFSTR("idProduct"), kCFAllocatorDefault,
      kIORegistryIterateRecursively | kIORegistryIterateParents);

  auto cleanupVendorIdAndProductId = MakeScopeExit([&]() {
    if (vendorIdRef) CFRelease(vendorIdRef);
    if (productIdRef) CFRelease(productIdRef);
  });

  if (vendorIdRef && productIdRef &&
      CFGetTypeID(vendorIdRef) == CFNumberGetTypeID() &&
      CFGetTypeID(productIdRef) == CFNumberGetTypeID()) {
    SInt32 vendorId, productId;
    if (CFNumberGetValue((CFNumberRef)vendorIdRef, kCFNumberSInt32Type,
                         &vendorId) &&
        CFNumberGetValue((CFNumberRef)productIdRef, kCFNumberSInt32Type,
                         &productId)) {
      portInfo.usbVendorId() = Some(static_cast<uint16_t>(vendorId));
      portInfo.usbProductId() = Some(static_cast<uint16_t>(productId));
    }
  }

  CFTypeRef productNameRef = IORegistryEntrySearchCFProperty(
      device, kIOServicePlane, CFSTR(kUSBProductString), kCFAllocatorDefault,
      kIORegistryIterateRecursively | kIORegistryIterateParents);
  auto cleanupProductName = MakeScopeExit([&]() {
    if (productNameRef) CFRelease(productNameRef);
  });

  if (productNameRef) {
    if (CFGetTypeID(productNameRef) == CFStringGetTypeID()) {
      char productName[kDeviceNameBufferSize];
      if (CFStringGetCString((CFStringRef)productNameRef, productName,
                             sizeof(productName), kCFStringEncodingUTF8)) {
        NS_ConvertUTF8toUTF16 friendlyName(productName);
        portInfo.friendlyName() = friendlyName;
      }
    }
  }

  if (portInfo.friendlyName().IsEmpty()) {
    portInfo.friendlyName() = path;
  }

  return true;
}

void PosixSerialPlatformService::DeviceAddedCallback(void* context,
                                                     io_iterator_t iterator) {
  PosixSerialPlatformService* service =
      static_cast<PosixSerialPlatformService*>(context);
  MOZ_LOG(
      gWebSerialLog, LogLevel::Debug,
      ("PosixSerialPlatformService[%p]::DeviceAddedCallback invoked", service));
  service->OnDeviceAdded(iterator, false);
}

void PosixSerialPlatformService::DeviceRemovedCallback(void* context,
                                                       io_iterator_t iterator) {
  PosixSerialPlatformService* service =
      static_cast<PosixSerialPlatformService*>(context);
  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::DeviceRemovedCallback invoked",
           service));
  service->OnDeviceRemoved(iterator, false);
}

void PosixSerialPlatformService::OnDeviceAdded(io_iterator_t iterator,
                                               bool aSkipNotify) {
  io_service_t device;
  int deviceCount = 0;
  while ((device = IOIteratorNext(iterator))) {
    deviceCount++;
    IPCSerialPortInfo portInfo;
    if (ExtractDeviceInfo(device, portInfo)) {
      MOZ_LOG(gWebSerialLog, LogLevel::Debug,
              ("PosixSerialPlatformService[%p]::OnDeviceAdded skip=%d device "
               ": path=%s, friendlyName=%s, VID=0x%04x, PID=0x%04x",
               this, aSkipNotify, NS_ConvertUTF16toUTF8(portInfo.path()).get(),
               NS_ConvertUTF16toUTF8(portInfo.friendlyName()).get(),
               portInfo.usbVendorId().valueOr(0),
               portInfo.usbProductId().valueOr(0)));
      if (!aSkipNotify) {
        NotifyPortConnected(portInfo);
      }
    }

    IOObjectRelease(device);
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::OnDeviceAdded processed %d devices "
           "(skipNotify=%d)",
           this, deviceCount, aSkipNotify));
}

void PosixSerialPlatformService::OnDeviceRemoved(io_iterator_t iterator,
                                                 bool aSkipNotify) {
  io_service_t device;
  int deviceCount = 0;
  while ((device = IOIteratorNext(iterator))) {
    deviceCount++;
    IPCSerialPortInfo portInfo;
    if (ExtractDeviceInfo(device, portInfo)) {
      MOZ_LOG(
          gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::OnDeviceRemoved skip=%d "
           "device: path=%s",
           this, aSkipNotify, NS_ConvertUTF16toUTF8(portInfo.path()).get()));
      if (!aSkipNotify) {
        NotifyPortDisconnected(portInfo.path());
      }
    } else {
      MOZ_LOG(gWebSerialLog, LogLevel::Warning,
              ("PosixSerialPlatformService[%p]::OnDeviceRemoved failed to "
               "extract device info, device may have been terminated",
               this));
    }

    IOObjectRelease(device);
  }

  MOZ_LOG(gWebSerialLog, LogLevel::Debug,
          ("PosixSerialPlatformService[%p]::OnDeviceRemoved processed %d "
           "devices (skipNotify=%d)",
           this, deviceCount, aSkipNotify));
}
#endif

}  // namespace mozilla::dom