source: imaps-frontend/node_modules/@parcel/watcher/src/watchman/IPC.hh

#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