Function createWritableStdioStream

lib/internal/bootstrap/switches/is_main_thread.js:50–112

(fd)

const { guessHandleType } = require('internal/util');

function createWritableStdioStream(fd) {
  let stream;
  // Note stream._type is used for test-module-load-list.js
  switch (guessHandleType(fd)) {
    case 'TTY': {
      const tty = require('tty');
      stream = new tty.WriteStream(fd);
      stream._type = 'tty';
      break;
    }

    case 'FILE': {
      const SyncWriteStream = require('internal/fs/sync_write_stream');
      stream = new SyncWriteStream(fd, { autoClose: false });
      stream._type = 'fs';
      break;
    }

    case 'PIPE':
    case 'TCP': {
      const net = require('net');

      // If fd is already being used for the IPC channel, libuv will return
      // an error when trying to use it again. In that case, create the socket
      // using the existing handle instead of the fd.
      if (process.channel && process.channel.fd === fd) {
        const { kChannelHandle } = require('internal/child_process');
        stream = new net.Socket({
          handle: process[kChannelHandle],
          readable: false,
          writable: true,
        });
      } else {
        stream = new net.Socket({
          fd,
          readable: false,
          writable: true,
        });
      }

      stream._type = 'pipe';
      break;
    }

    default: {
      // Provide a dummy black-hole output for e.g. non-console
      // Windows applications.
      const { Writable } = require('stream');
      stream = new Writable({
        write(buf, enc, cb) {
          cb();
        },
      });
    }
  }

  // For supporting legacy API we put the FD here.
  stream.fd = fd;