Uploading the main structure

node_modules/@parcel/watcher/src/watchman/BSER.cc

@@ -0,0 +1,302 @@
+#include <stdint.h>
+#include "./BSER.hh"
+
+BSERType decodeType(std::istream &iss) {
+  int8_t type;
+  iss.read(reinterpret_cast<char*>(&type), sizeof(type));
+  return (BSERType) type;
+}
+
+void expectType(std::istream &iss, BSERType expected) {
+  BSERType got = decodeType(iss);
+  if (got != expected) {
+    throw std::runtime_error("Unexpected BSER type");
+  }
+}
+
+void encodeType(std::ostream &oss, BSERType type) {
+  int8_t t = (int8_t)type;
+  oss.write(reinterpret_cast<char*>(&t), sizeof(t));
+}
+
+template<typename T>
+class Value : public BSERValue {
+public:
+  T value;
+  Value(T val) {
+    value = val;
+  }
+
+  Value() {}
+};
+
+class BSERInteger : public Value<int64_t> {
+public:
+  BSERInteger(int64_t value) : Value(value) {}
+  BSERInteger(std::istream &iss) {
+    int8_t int8;
+    int16_t int16;
+    int32_t int32;
+    int64_t int64;
+
+    BSERType type = decodeType(iss);
+
+    switch (type) {
+      case BSER_INT8:
+        iss.read(reinterpret_cast<char*>(&int8), sizeof(int8));
+        value = int8;
+        break;
+      case BSER_INT16:
+        iss.read(reinterpret_cast<char*>(&int16), sizeof(int16));
+        value = int16;
+        break;
+      case BSER_INT32:
+        iss.read(reinterpret_cast<char*>(&int32), sizeof(int32));
+        value = int32;
+        break;
+      case BSER_INT64:
+        iss.read(reinterpret_cast<char*>(&int64), sizeof(int64));
+        value = int64;
+        break;
+      default:
+        throw std::runtime_error("Invalid BSER int type");
+    }
+  }
+
+  int64_t intValue() override {
+    return value;
+  }
+
+  void encode(std::ostream &oss) override {
+    if (value <= INT8_MAX) {
+      encodeType(oss, BSER_INT8);
+      int8_t v = (int8_t)value;
+      oss.write(reinterpret_cast<char*>(&v), sizeof(v));
+    } else if (value <= INT16_MAX) {
+      encodeType(oss, BSER_INT16);
+      int16_t v = (int16_t)value;
+      oss.write(reinterpret_cast<char*>(&v), sizeof(v));
+    } else if (value <= INT32_MAX) {
+      encodeType(oss, BSER_INT32);
+      int32_t v = (int32_t)value;
+      oss.write(reinterpret_cast<char*>(&v), sizeof(v));
+    } else {
+      encodeType(oss, BSER_INT64);
+      oss.write(reinterpret_cast<char*>(&value), sizeof(value));
+    }
+  }
+};
+
+class BSERArray : public Value<BSER::Array> {
+public:
+  BSERArray() : Value() {}
+  BSERArray(BSER::Array value) : Value(value) {}
+  BSERArray(std::istream &iss) {
+    expectType(iss, BSER_ARRAY);
+    int64_t len = BSERInteger(iss).intValue();
+    for (int64_t i = 0; i < len; i++) {
+      value.push_back(BSER(iss));
+    }
+  }
+  
+  BSER::Array arrayValue() override {
+    return value;
+  }
+
+  void encode(std::ostream &oss) override {
+    encodeType(oss, BSER_ARRAY);
+    BSERInteger(value.size()).encode(oss);
+    for (auto it = value.begin(); it != value.end(); it++) {
+      it->encode(oss);
+    }
+  }
+};
+
+class BSERString : public Value<std::string> {
+public:
+  BSERString(std::string value) : Value(value) {}
+  BSERString(std::istream &iss) {
+    expectType(iss, BSER_STRING);
+    int64_t len = BSERInteger(iss).intValue();
+    value.resize(len);
+    iss.read(&value[0], len);
+  }
+
+  std::string stringValue() override {
+    return value;
+  }
+
+  void encode(std::ostream &oss) override {
+    encodeType(oss, BSER_STRING);
+    BSERInteger(value.size()).encode(oss);
+    oss << value;
+  }
+};
+
+class BSERObject : public Value<BSER::Object> {
+public:
+  BSERObject() : Value() {}
+  BSERObject(BSER::Object value) : Value(value) {}
+  BSERObject(std::istream &iss) {
+    expectType(iss, BSER_OBJECT);
+    int64_t len = BSERInteger(iss).intValue();
+    for (int64_t i = 0; i < len; i++) {
+      auto key = BSERString(iss).stringValue();
+      auto val = BSER(iss);
+      value.emplace(key, val);
+    }
+  }
+
+  BSER::Object objectValue() override {
+    return value;
+  }
+
+  void encode(std::ostream &oss) override {
+    encodeType(oss, BSER_OBJECT);
+    BSERInteger(value.size()).encode(oss);
+    for (auto it = value.begin(); it != value.end(); it++) {
+      BSERString(it->first).encode(oss);
+      it->second.encode(oss);
+    }
+  }
+};
+
+class BSERDouble : public Value<double> {
+public:
+  BSERDouble(double value) : Value(value) {}
+  BSERDouble(std::istream &iss) {
+    expectType(iss, BSER_REAL);
+    iss.read(reinterpret_cast<char*>(&value), sizeof(value));
+  }
+
+  double doubleValue() override {
+    return value;
+  }
+
+  void encode(std::ostream &oss) override {
+    encodeType(oss, BSER_REAL);
+    oss.write(reinterpret_cast<char*>(&value), sizeof(value));
+  }
+};
+
+class BSERBoolean : public Value<bool> {
+public:
+  BSERBoolean(bool value) : Value(value) {}
+  bool boolValue() override { return value; }
+  void encode(std::ostream &oss) override {
+    int8_t t = value == true ? BSER_BOOL_TRUE : BSER_BOOL_FALSE;
+    oss.write(reinterpret_cast<char*>(&t), sizeof(t));
+  }
+};
+
+class BSERNull : public Value<bool> {
+public:
+  BSERNull() : Value(false) {}
+  void encode(std::ostream &oss) override {
+    encodeType(oss, BSER_NULL);
+  }
+};
+
+std::shared_ptr<BSERArray> decodeTemplate(std::istream &iss) {
+  expectType(iss, BSER_TEMPLATE);
+  auto keys = BSERArray(iss).arrayValue();
+  auto len = BSERInteger(iss).intValue();
+  std::shared_ptr<BSERArray> arr = std::make_shared<BSERArray>();
+  for (int64_t i = 0; i < len; i++) {
+    BSER::Object obj;
+    for (auto it = keys.begin(); it != keys.end(); it++) {
+      if (iss.peek() == 0x0c) {
+        iss.ignore(1);
+        continue;
+      }
+
+      auto val = BSER(iss);
+      obj.emplace(it->stringValue(), val);
+    }
+    arr->value.push_back(obj);
+  }
+  return arr;
+}
+
+BSER::BSER(std::istream &iss) {
+  BSERType type = decodeType(iss);
+  iss.unget();
+
+  switch (type) {
+    case BSER_ARRAY:
+      m_ptr = std::make_shared<BSERArray>(iss);
+      break;
+    case BSER_OBJECT:
+      m_ptr = std::make_shared<BSERObject>(iss);
+      break;
+    case BSER_STRING:
+      m_ptr = std::make_shared<BSERString>(iss);
+      break;
+    case BSER_INT8:
+    case BSER_INT16:
+    case BSER_INT32:
+    case BSER_INT64:
+      m_ptr = std::make_shared<BSERInteger>(iss);
+      break;
+    case BSER_REAL:
+      m_ptr = std::make_shared<BSERDouble>(iss);
+      break;
+    case BSER_BOOL_TRUE:
+      iss.ignore(1);
+      m_ptr = std::make_shared<BSERBoolean>(true);
+      break;
+    case BSER_BOOL_FALSE:
+      iss.ignore(1);
+      m_ptr = std::make_shared<BSERBoolean>(false);
+      break;
+    case BSER_NULL:
+      iss.ignore(1);
+      m_ptr = std::make_shared<BSERNull>();
+      break;
+    case BSER_TEMPLATE:
+      m_ptr = decodeTemplate(iss);
+      break;
+    default:
+      throw std::runtime_error("unknown BSER type");
+  }
+}
+
+BSER::BSER() : m_ptr(std::make_shared<BSERNull>()) {}
+BSER::BSER(BSER::Array value) : m_ptr(std::make_shared<BSERArray>(value)) {}
+BSER::BSER(BSER::Object value) : m_ptr(std::make_shared<BSERObject>(value)) {}
+BSER::BSER(const char *value) : m_ptr(std::make_shared<BSERString>(value)) {}
+BSER::BSER(std::string value) : m_ptr(std::make_shared<BSERString>(value)) {}
+BSER::BSER(int64_t value) : m_ptr(std::make_shared<BSERInteger>(value)) {}
+BSER::BSER(double value) : m_ptr(std::make_shared<BSERDouble>(value)) {}
+BSER::BSER(bool value) : m_ptr(std::make_shared<BSERBoolean>(value)) {}
+
+BSER::Array BSER::arrayValue() { return m_ptr->arrayValue(); }
+BSER::Object BSER::objectValue() { return m_ptr->objectValue(); }
+std::string BSER::stringValue() { return m_ptr->stringValue(); }
+int64_t BSER::intValue() { return m_ptr->intValue(); }
+double BSER::doubleValue() { return m_ptr->doubleValue(); }
+bool BSER::boolValue() { return m_ptr->boolValue(); }
+void BSER::encode(std::ostream &oss) {
+  m_ptr->encode(oss);
+}
+
+int64_t BSER::decodeLength(std::istream &iss) {
+  char pdu[2];
+  if (!iss.read(pdu, 2) || pdu[0] != 0 || pdu[1] != 1) {
+    throw std::runtime_error("Invalid BSER");
+  }
+
+  return BSERInteger(iss).intValue();
+}
+
+std::string BSER::encode() {
+  std::ostringstream oss(std::ios_base::binary);
+  encode(oss);
+
+  std::ostringstream res(std::ios_base::binary);
+  res.write("\x00\x01", 2);
+  
+  BSERInteger(oss.str().size()).encode(res);
+  res << oss.str();
+  return res.str();
+}

node_modules/@parcel/watcher/src/watchman/BSER.hh

@@ -0,0 +1,69 @@
+#ifndef BSER_H
+#define BSER_H
+
+#include <string>
+#include <sstream>
+#include <vector>
+#include <unordered_map>
+#include <memory>
+
+enum BSERType {
+  BSER_ARRAY = 0x00,
+  BSER_OBJECT = 0x01,
+  BSER_STRING = 0x02,
+  BSER_INT8 = 0x03,
+  BSER_INT16 = 0x04,
+  BSER_INT32 = 0x05,
+  BSER_INT64 = 0x06,
+  BSER_REAL = 0x07,
+  BSER_BOOL_TRUE = 0x08,
+  BSER_BOOL_FALSE = 0x09,
+  BSER_NULL = 0x0a,
+  BSER_TEMPLATE = 0x0b
+};
+
+class BSERValue;
+
+class BSER {
+public:
+  typedef std::vector<BSER> Array;
+  typedef std::unordered_map<std::string, BSER> Object;
+
+  BSER();
+  BSER(BSER::Array value);
+  BSER(BSER::Object value);
+  BSER(std::string value);
+  BSER(const char *value);
+  BSER(int64_t value);
+  BSER(double value);
+  BSER(bool value);
+  BSER(std::istream &iss);
+
+  BSER::Array arrayValue();
+  BSER::Object objectValue();
+  std::string stringValue();
+  int64_t intValue();
+  double doubleValue();
+  bool boolValue();
+  void encode(std::ostream &oss);
+
+  static int64_t decodeLength(std::istream &iss);
+  std::string encode();
+private:
+  std::shared_ptr<BSERValue> m_ptr;
+};
+
+class BSERValue {
+protected:
+  friend class BSER;
+  virtual BSER::Array arrayValue() { return BSER::Array(); }
+  virtual BSER::Object objectValue() { return BSER::Object(); }
+  virtual std::string stringValue() { return std::string(); }
+  virtual int64_t intValue() { return 0; }
+  virtual double doubleValue() { return 0; }
+  virtual bool boolValue() { return false; }
+  virtual void encode(std::ostream &oss) {}
+  virtual ~BSERValue() {}
+};
+
+#endif

node_modules/@parcel/watcher/src/watchman/IPC.hh

@@ -0,0 +1,175 @@
+#ifndef IPC_H
+#define IPC_H
+
+#include <string>
+#include <stdlib.h>
+
+#ifdef _WIN32
+#include <winsock2.h>
+#include <windows.h>
+#else
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#endif
+
+class IPC {
+public:
+  IPC(std::string path) {
+    mStopped = false;
+    #ifdef _WIN32
+      while (true) {
+        mPipe = CreateFile(
+          path.data(), // pipe name
+          GENERIC_READ | GENERIC_WRITE, // read and write access
+          0, // no sharing
+          NULL, // default security attributes
+          OPEN_EXISTING, // opens existing pipe
+          FILE_FLAG_OVERLAPPED, // attributes
+          NULL // no template file
+        );
+
+        if (mPipe != INVALID_HANDLE_VALUE) {
+          break;
+        }
+
+        if (GetLastError() != ERROR_PIPE_BUSY) {
+          throw std::runtime_error("Could not open pipe");
+        }
+
+        // Wait for pipe to become available if it is busy
+        if (!WaitNamedPipe(path.data(), 30000)) {
+          throw std::runtime_error("Error waiting for pipe");
+        }
+      }
+
+      mReader = CreateEvent(NULL, true, false, NULL);
+      mWriter = CreateEvent(NULL, true, false, NULL);
+    #else
+      struct sockaddr_un addr;
+      memset(&addr, 0, sizeof(addr));
+      addr.sun_family = AF_UNIX;
+      strncpy(addr.sun_path, path.c_str(), sizeof(addr.sun_path) - 1);
+
+      mSock = socket(AF_UNIX, SOCK_STREAM, 0);
+      if (connect(mSock, (struct sockaddr *) &addr, sizeof(struct sockaddr_un))) {
+        throw std::runtime_error("Error connecting to socket");
+      }
+    #endif
+  }
+
+  ~IPC() {
+    mStopped = true;
+    #ifdef _WIN32
+      CancelIo(mPipe);
+      CloseHandle(mPipe);
+      CloseHandle(mReader);
+      CloseHandle(mWriter);
+    #else
+      shutdown(mSock, SHUT_RDWR);
+    #endif
+  }
+
+  void write(std::string buf) {
+    #ifdef _WIN32
+      OVERLAPPED overlapped;
+      overlapped.hEvent = mWriter;
+      bool success = WriteFile(
+        mPipe, // pipe handle
+        buf.data(), // message
+        buf.size(), // message length
+        NULL, // bytes written
+        &overlapped // overlapped
+      );
+
+      if (mStopped) {
+        return;
+      }
+
+      if (!success) {
+        if (GetLastError() != ERROR_IO_PENDING) {
+          throw std::runtime_error("Write error");
+        }
+      }
+
+      DWORD written;
+      success = GetOverlappedResult(mPipe, &overlapped, &written, true);
+      if (!success) {
+        throw std::runtime_error("GetOverlappedResult failed");
+      }
+
+      if (written != buf.size()) {
+        throw std::runtime_error("Wrong number of bytes written");
+      }
+    #else
+      int r = 0;
+      for (unsigned int i = 0; i != buf.size(); i += r) {
+        r = ::write(mSock, &buf[i], buf.size() - i);
+        if (r == -1) {
+          if (errno == EAGAIN) {
+            r = 0;
+          } else if (mStopped) {
+            return;
+          } else {
+            throw std::runtime_error("Write error");
+          }
+        }
+      }
+    #endif
+  }
+
+  int read(char *buf, size_t len) {
+    #ifdef _WIN32
+      OVERLAPPED overlapped;
+      overlapped.hEvent = mReader;
+      bool success = ReadFile(
+        mPipe, // pipe handle
+        buf, // buffer to receive reply
+        len, // size of buffer
+        NULL, // number of bytes read
+        &overlapped // overlapped
+      );
+
+      if (!success && !mStopped) {
+        if (GetLastError() != ERROR_IO_PENDING) {
+          throw std::runtime_error("Read error");
+        }
+      }
+
+      DWORD read = 0;
+      success = GetOverlappedResult(mPipe, &overlapped, &read, true);
+      if (!success && !mStopped) {
+        throw std::runtime_error("GetOverlappedResult failed");
+      }
+
+      return read;
+    #else
+      int r = ::read(mSock, buf, len);
+      if (r == 0 && !mStopped) {
+        throw std::runtime_error("Socket ended unexpectedly");
+      }
+
+      if (r < 0) {
+        if (mStopped) {
+          return 0;
+        }
+
+        throw std::runtime_error(strerror(errno));
+      }
+
+      return r;
+    #endif
+  }
+
+private:
+  bool mStopped;
+  #ifdef _WIN32
+    HANDLE mPipe;
+    HANDLE mReader;
+    HANDLE mWriter;
+  #else
+    int mSock;
+  #endif
+};
+
+#endif

node_modules/@parcel/watcher/src/watchman/WatchmanBackend.cc

@@ -0,0 +1,338 @@
+#include <string>
+#include <fstream>
+#include <stdlib.h>
+#include <algorithm>
+#include "../DirTree.hh"
+#include "../Event.hh"
+#include "./BSER.hh"
+#include "./WatchmanBackend.hh"
+
+#ifdef _WIN32
+#include "../windows/win_utils.hh"
+#define S_ISDIR(mode) ((mode & _S_IFDIR) == _S_IFDIR)
+#define popen _popen
+#define pclose _pclose
+#else
+#include <sys/stat.h>
+#define normalizePath(dir) dir
+#endif
+
+template<typename T>
+BSER readBSER(T &&do_read) {
+  std::stringstream oss;
+  char buffer[256];
+  int r;
+  int64_t len = -1;
+  do {
+    // Start by reading a minimal amount of data in order to decode the length.
+    // After that, attempt to read the remaining length, up to the buffer size.
+    r = do_read(buffer, len == -1 ? 20 : (len < 256 ? len : 256));
+    oss << std::string(buffer, r);
+
+    if (len == -1) {
+      uint64_t l = BSER::decodeLength(oss);
+      len = l + oss.tellg();
+    }
+
+    len -= r;
+  } while (len > 0);
+
+  return BSER(oss);
+}
+
+std::string getSockPath() {
+  auto var = getenv("WATCHMAN_SOCK");
+  if (var && *var) {
+    return std::string(var);
+  }
+
+  FILE *fp = popen("watchman --output-encoding=bser get-sockname", "r");
+  if (fp == NULL || errno == ECHILD) {
+    throw std::runtime_error("Failed to execute watchman");
+  }
+
+  BSER b = readBSER([fp] (char *buf, size_t len) {
+    return fread(buf, sizeof(char), len, fp);
+  });
+
+  pclose(fp);
+
+  auto objValue = b.objectValue();
+  auto foundSockname = objValue.find("sockname");
+  if (foundSockname == objValue.end()) {
+    throw std::runtime_error("sockname not found");
+  }
+  return foundSockname->second.stringValue();
+}
+
+std::unique_ptr<IPC> watchmanConnect() {
+  std::string path = getSockPath();
+  return std::unique_ptr<IPC>(new IPC(path));
+}
+
+BSER watchmanRead(IPC *ipc) {
+  return readBSER([ipc] (char *buf, size_t len) {
+    return ipc->read(buf, len);
+  });
+}
+
+BSER::Object WatchmanBackend::watchmanRequest(BSER b) {
+  std::string cmd = b.encode();
+  mIPC->write(cmd);
+  mRequestSignal.notify();
+
+  mResponseSignal.wait();
+  mResponseSignal.reset();
+
+  if (!mError.empty()) {
+    std::runtime_error err = std::runtime_error(mError);
+    mError = std::string();
+    throw err;
+  }
+
+  return mResponse;
+}
+
+void WatchmanBackend::watchmanWatch(std::string dir) {
+  std::vector<BSER> cmd;
+  cmd.push_back("watch");
+  cmd.push_back(normalizePath(dir));
+  watchmanRequest(cmd);
+}
+
+bool WatchmanBackend::checkAvailable() {
+  try {
+    watchmanConnect();
+    return true;
+  } catch (std::exception &err) {
+    return false;
+  }
+}
+
+void handleFiles(WatcherRef watcher, BSER::Object obj) {
+  auto found = obj.find("files");
+  if (found == obj.end()) {
+    throw WatcherError("Error reading changes from watchman", watcher);
+  }
+
+  auto files = found->second.arrayValue();
+  for (auto it = files.begin(); it != files.end(); it++) {
+    auto file = it->objectValue();
+    auto name = file.find("name")->second.stringValue();
+    #ifdef _WIN32
+      std::replace(name.begin(), name.end(), '/', '\\');
+    #endif
+    auto mode = file.find("mode")->second.intValue();
+    auto isNew = file.find("new")->second.boolValue();
+    auto exists = file.find("exists")->second.boolValue();
+    auto path = watcher->mDir + DIR_SEP + name;
+    if (watcher->isIgnored(path)) {
+      continue;
+    }
+
+    if (isNew && exists) {
+      watcher->mEvents.create(path);
+    } else if (exists && !S_ISDIR(mode)) {
+      watcher->mEvents.update(path);
+    } else if (!isNew && !exists) {
+      watcher->mEvents.remove(path);
+    }
+  }
+}
+
+void WatchmanBackend::handleSubscription(BSER::Object obj) {
+  std::unique_lock<std::mutex> lock(mMutex);
+  auto subscription = obj.find("subscription")->second.stringValue();
+  auto it = mSubscriptions.find(subscription);
+  if (it == mSubscriptions.end()) {
+    return;
+  }
+
+  auto watcher = it->second;
+  try {
+    handleFiles(watcher, obj);
+    watcher->notify();
+  } catch (WatcherError &err) {
+    handleWatcherError(err);
+  }
+}
+
+void WatchmanBackend::start() {
+  mIPC = watchmanConnect();
+  notifyStarted();
+
+  while (true) {
+    // If there are no subscriptions we are reading, wait for a request.
+    if (mSubscriptions.size() == 0) {
+      mRequestSignal.wait();
+      mRequestSignal.reset();
+    }
+
+    // Break out of loop if we are stopped.
+    if (mStopped) {
+      break;
+    }
+
+    // Attempt to read from the socket.
+    // If there is an error and we are stopped, break.
+    BSER b;
+    try {
+      b = watchmanRead(&*mIPC);
+    } catch (std::exception &err) {
+      if (mStopped) {
+        break;
+      } else if (mResponseSignal.isWaiting()) {
+        mError = err.what();
+        mResponseSignal.notify();
+      } else {
+        // Throwing causes the backend to be destroyed, but we never reach the code below to notify the signal
+        mEndedSignal.notify();
+        throw;
+      }
+    }
+
+    auto obj = b.objectValue();
+    auto error = obj.find("error");
+    if (error != obj.end()) {
+      mError = error->second.stringValue();
+      mResponseSignal.notify();
+      continue;
+    }
+
+    // If this message is for a subscription, handle it, otherwise notify the request.
+    auto subscription = obj.find("subscription");
+    if (subscription != obj.end()) {
+      handleSubscription(obj);
+    } else {
+      mResponse = obj;
+      mResponseSignal.notify();
+    }
+  }
+
+  mEndedSignal.notify();
+}
+
+WatchmanBackend::~WatchmanBackend() {
+  // Mark the watcher as stopped, close the socket, and trigger the lock.
+  // This will cause the read loop to be broken and the thread to exit.
+  mStopped = true;
+  mIPC.reset();
+  mRequestSignal.notify();
+
+  // If not ended yet, wait.
+  mEndedSignal.wait();
+}
+
+std::string WatchmanBackend::clock(WatcherRef watcher) {
+  BSER::Array cmd;
+  cmd.push_back("clock");
+  cmd.push_back(normalizePath(watcher->mDir));
+
+  BSER::Object obj = watchmanRequest(cmd);
+  auto found = obj.find("clock");
+  if (found == obj.end()) {
+    throw WatcherError("Error reading clock from watchman", watcher);
+  }
+
+  return found->second.stringValue();
+}
+
+void WatchmanBackend::writeSnapshot(WatcherRef watcher, std::string *snapshotPath) {
+  std::unique_lock<std::mutex> lock(mMutex);
+  watchmanWatch(watcher->mDir);
+
+  std::ofstream ofs(*snapshotPath);
+  ofs << clock(watcher);
+}
+
+void WatchmanBackend::getEventsSince(WatcherRef watcher, std::string *snapshotPath) {
+  std::unique_lock<std::mutex> lock(mMutex);
+  std::ifstream ifs(*snapshotPath);
+  if (ifs.fail()) {
+    return;
+  }
+
+  watchmanWatch(watcher->mDir);
+
+  std::string clock;
+  ifs >> clock;
+
+  BSER::Array cmd;
+  cmd.push_back("since");
+  cmd.push_back(normalizePath(watcher->mDir));
+  cmd.push_back(clock);
+
+  BSER::Object obj = watchmanRequest(cmd);
+  handleFiles(watcher, obj);
+}
+
+std::string getId(WatcherRef watcher) {
+  std::ostringstream id;
+  id << "parcel-";
+  id << static_cast<void*>(watcher.get());
+  return id.str();
+}
+
+// This function is called by Backend::watch which takes a lock on mMutex
+void WatchmanBackend::subscribe(WatcherRef watcher) {
+  watchmanWatch(watcher->mDir);
+
+  std::string id = getId(watcher);
+  BSER::Array cmd;
+  cmd.push_back("subscribe");
+  cmd.push_back(normalizePath(watcher->mDir));
+  cmd.push_back(id);
+
+  BSER::Array fields;
+  fields.push_back("name");
+  fields.push_back("mode");
+  fields.push_back("exists");
+  fields.push_back("new");
+
+  BSER::Object opts;
+  opts.emplace("fields", fields);
+  opts.emplace("since", clock(watcher));
+
+  if (watcher->mIgnorePaths.size() > 0) {
+    BSER::Array ignore;
+    BSER::Array anyOf;
+    anyOf.push_back("anyof");
+
+    for (auto it = watcher->mIgnorePaths.begin(); it != watcher->mIgnorePaths.end(); it++) {
+      std::string pathStart = watcher->mDir + DIR_SEP;
+      if (it->rfind(pathStart, 0) == 0) {
+        auto relative = it->substr(pathStart.size());
+        BSER::Array dirname;
+        dirname.push_back("dirname");
+        dirname.push_back(relative);
+        anyOf.push_back(dirname);
+      }
+    }
+
+    ignore.push_back("not");
+    ignore.push_back(anyOf);
+
+    opts.emplace("expression", ignore);
+  }
+
+  cmd.push_back(opts);
+  watchmanRequest(cmd);
+
+  mSubscriptions.emplace(id, watcher);
+  mRequestSignal.notify();
+}
+
+// This function is called by Backend::unwatch which takes a lock on mMutex
+void WatchmanBackend::unsubscribe(WatcherRef watcher) {
+  std::string id = getId(watcher);
+  auto erased = mSubscriptions.erase(id);
+
+  if (erased) {
+    BSER::Array cmd;
+    cmd.push_back("unsubscribe");
+    cmd.push_back(normalizePath(watcher->mDir));
+    cmd.push_back(id);
+
+    watchmanRequest(cmd);
+  }
+}

node_modules/@parcel/watcher/src/watchman/WatchmanBackend.hh

@@ -0,0 +1,35 @@
+#ifndef WATCHMAN_H
+#define WATCHMAN_H
+
+#include "../Backend.hh"
+#include "./BSER.hh"
+#include "../Signal.hh"
+#include "./IPC.hh"
+
+class WatchmanBackend : public Backend {
+public:
+  static bool checkAvailable();
+  void start() override;
+  WatchmanBackend() : mStopped(false) {};
+  ~WatchmanBackend();
+  void writeSnapshot(WatcherRef watcher, std::string *snapshotPath) override;
+  void getEventsSince(WatcherRef watcher, std::string *snapshotPath) override;
+  void subscribe(WatcherRef watcher) override;
+  void unsubscribe(WatcherRef watcher) override;
+private:
+  std::unique_ptr<IPC> mIPC;
+  Signal mRequestSignal;
+  Signal mResponseSignal;
+  BSER::Object mResponse;
+  std::string mError;
+  std::unordered_map<std::string, WatcherRef> mSubscriptions;
+  bool mStopped;
+  Signal mEndedSignal;
+
+  std::string clock(WatcherRef watcher);
+  void watchmanWatch(std::string dir);
+  BSER::Object watchmanRequest(BSER cmd);
+  void handleSubscription(BSER::Object obj);
+};
+
+#endif