serialport.js

/*jslint node: true */
"use strict";

// Copyright 2011 Chris Williams <chris@iterativedesigns.com>

// Require serialport binding from pre-compiled binaries using
// node-pre-gyp, if something fails or package not available fallback
// to regular build from source.

var binary = require('node-pre-gyp');
var path = require('path');
var binding_path = binary.find(path.resolve(path.join(__dirname,'./package.json')));
var SerialPortBinding = require(binding_path);

var parsers = require('./parsers');
var EventEmitter = require('events').EventEmitter;
var util = require('util');
var fs = require('fs');
var stream = require('stream');
var path = require('path');
var async = require('async');

function SerialPortFactory() {

  var factory = this;

  // Removing check for valid BaudRates due to ticket: #140
  // var BAUDRATES = [500000, 230400, 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1800, 1200, 600, 300, 200, 150, 134, 110, 75, 50];

  //  VALIDATION ARRAYS
  var DATABITS = [5, 6, 7, 8];
  var STOPBITS = [1, 1.5, 2];
  var PARITY = ['none', 'even', 'mark', 'odd', 'space'];
  var FLOWCONTROLS = ["XON", "XOFF", "XANY", "RTSCTS"];


  // Stuff from ReadStream, refactored for our usage:
  var kPoolSize = 40 * 1024;
  var kMinPoolSpace = 128;

  // The default options, can be overwritten in the 'SerialPort' constructor
  var _options = {
    baudrate: 9600,
    parity: 'none',
    rtscts: false,
    xon: false,
    xoff: false,
    xany: false,
    databits: 8,
    stopbits: 1,
    buffersize: 256,
    parser: parsers.raw
  };

  function SerialPort(path, options, openImmediately, callback) {

    var self = this;

    var args = Array.prototype.slice.call(arguments);
    callback = args.pop();
    if (typeof(callback) !== 'function') {
      callback = null;
    }

    options = (typeof options !== 'function') && options || {};

    openImmediately = (openImmediately === undefined || openImmediately === null) ? true : openImmediately;

    stream.Stream.call(this);

    callback = callback || function (err) {
      if (err) {
        factory.emit('error', err);
      }
    };

    var err;

    options.baudRate = options.baudRate || options.baudrate || _options.baudrate;

    options.dataBits = options.dataBits || options.databits || _options.databits;
    if (DATABITS.indexOf(options.dataBits) === -1) {
      err = new Error('Invalid "databits": ' + options.dataBits);
      callback(err);
      return;
    }

    options.stopBits = options.stopBits || options.stopbits || _options.stopbits;
    if (STOPBITS.indexOf(options.stopBits) === -1) {
      err = new Error('Invalid "stopbits": ' + options.stopbits);
      callback(err);
      return;
    }

    options.parity = options.parity || _options.parity;
    if (PARITY.indexOf(options.parity) === -1) {
      err = new Error('Invalid "parity": ' + options.parity);
      callback(err);
      return;
    }
    if (!path) {
      err = new Error('Invalid port specified: ' + path);
      callback(err);
      return;
    }

    // flush defaults, then update with provided details
    options.rtscts = _options.rtscts;
    options.xon = _options.xon;
    options.xoff = _options.xoff;
    options.xany = _options.xany;

    if (options.flowControl || options.flowcontrol) {
      var fc = options.flowControl || options.flowcontrol;

      if (typeof fc === 'boolean') {
        options.rtscts = true;
      } else {
        fc.forEach(function (flowControl) {
          var fcup = flowControl.toUpperCase();
          var idx = FLOWCONTROLS.indexOf(fcup);
          if (idx < 0) {
            var err = new Error('Invalid "flowControl": ' + fcup + ". Valid options: " + FLOWCONTROLS.join(", "));
            callback(err);
            return;
          } else {

            // "XON", "XOFF", "XANY", "DTRDTS", "RTSCTS"
            switch (idx) {
              case 0: options.xon = true; break;
              case 1: options.xoff = true; break;
              case 2: options.xany = true;  break;
              case 3: options.rtscts = true; break;
            }
          }
        });
      }
    }

    options.bufferSize = options.bufferSize || options.buffersize || _options.buffersize;
    options.parser = options.parser || _options.parser;

    options.dataCallback = options.dataCallback || function (data) {
      options.parser(self, data);
    };

    options.disconnectedCallback = options.disconnectedCallback || function () {
      if (self.closing) {
        return;
      }
      var err = new Error("Disconnected");
      callback(err);
    };

    if (process.platform !== 'win32') {
      // All other platforms:
      this.fd = null;
      this.paused = true;
      this.bufferSize = options.bufferSize || 64 * 1024;
      this.readable = true;
      this.reading = false;

      if (options.encoding) {
        this.setEncoding(this.encoding);
      }
    }

    this.options = options;
    this.path = path;

    if (openImmediately) {
      process.nextTick(function () {
        self.open(callback);
      });
    }
  }

  util.inherits(SerialPort, stream.Stream);


  SerialPort.prototype.open = function (callback) {
    var self = this;
    this.paused = true;
    this.readable = true;
    this.reading = false;
    factory.SerialPortBinding.open(this.path, this.options, function (err, fd) {
      self.fd = fd;
      if (err) {
        if (callback) {
          callback(err);
        } else {
          self.emit('error', err);
        }
        return;
      }
      if (process.platform !== 'win32') {
        self.paused = false;
        self.serialPoller = new factory.SerialPortBinding.SerialportPoller(self.fd, function () { self._read(); });
        self.serialPoller.start();
      }

      self.emit('open');
      if (callback) { callback(); }
    });
  };

  SerialPort.prototype.write = function (buffer, callback) {
    var self = this;
    if (!this.fd) {
      var err = new Error("Serialport not open.");
      if (callback) {
        callback(err);
      } else {
        self.emit('error', err);
      }
      return;
    }

    if (!Buffer.isBuffer(buffer)) {
      buffer = new Buffer(buffer);
    }
    factory.SerialPortBinding.write(this.fd, buffer, function (err, results) {
      if (callback) {
        callback(err, results);
      } else {
        if (err) {
          self.emit('error', err);
        }
      }
    });
  };

  if (process.platform !== 'win32') {
    SerialPort.prototype._read = function () {
      var self = this;

      // console.log(">>READ");
      if (!self.readable || self.paused || self.reading) {
        return;
      }

      self.reading = true;

      if (!self.pool || self.pool.length - self.pool.used < kMinPoolSpace) {
        // discard the old pool. Can't add to the free list because
        // users might have refernces to slices on it.
        self.pool = null;

        // alloc new pool
        self.pool = new Buffer(kPoolSize);
        self.pool.used = 0;
      }

      // Grab another reference to the pool in the case that while we're in the
      // thread pool another read() finishes up the pool, and allocates a new
      // one.
      var toRead = Math.min(self.pool.length - self.pool.used, ~~self.bufferSize);
      var start = self.pool.used;

      function afterRead(err, bytesRead, readPool, bytesRequested) {
        self.reading = false;
        if (err) {
          if (err.code && err.code === 'EAGAIN') {
            if (self.fd >= 0) {
              self.serialPoller.start();
            }
          } else {
            self.fd = null;
            self.emit('error', err);
            self.readable = false;
          }
        }

        // Since we will often not read the number of bytes requested,
        // let's mark the ones we didn't need as available again.
        self.pool.used -= bytesRequested - bytesRead;

        if (bytesRead === 0) {
          if (self.fd >= 0) {
            self.serialPoller.start();
          }
        } else {
          var b = self.pool.slice(start, start + bytesRead);

          // do not emit events if the stream is paused
          if (self.paused) {
            self.buffer = Buffer.concat([self.buffer, b]);
            return;
          } else {
            self._emitData(b);
          }

          // do not emit events anymore after we declared the stream unreadable
          if (!self.readable) {
            return;
          }
          self._read();
        }
      }

      fs.read(self.fd, self.pool, self.pool.used, toRead, null, function (err, bytesRead) {
        var readPool = self.pool;
        var bytesRequested = toRead;
        afterRead(err, bytesRead, readPool, bytesRequested);
      });

      self.pool.used += toRead;
    };


    SerialPort.prototype._emitData = function (data) {
      this.options.dataCallback(data);
    };

    SerialPort.prototype.pause = function () {
      var self = this;
      self.paused = true;
    };

    SerialPort.prototype.resume = function () {
      var self = this;
      self.paused = false;

      if (self.buffer) {
        var buffer = self.buffer;
        self.buffer = null;
        self._emitData(buffer);
      }

      // No longer open?
      if (null === self.fd) {
        return;
      }

      self._read();
    };

  } // if !'win32'

  SerialPort.prototype.close = function (callback) {
    var self = this;

    var fd = self.fd;

    if (self.closing) {
      return;
    }
    if (!fd) {
      var err = new Error("Serialport not open.");
      if (callback) {
        callback(err);
      } else {
        self.emit('error', err);
      }
      return;
    }

    self.closing = true;
    try {
      factory.SerialPortBinding.close(fd, function (err) {

        if (err) {
          if (callback) {
            callback(err);
          } else {
            self.emit('error', err);
          }
          return;
        }

        self.emit('close');
        self.removeAllListeners();
        self.closing = false;
        self.fd = 0;

        if (process.platform !== 'win32') {
          self.readable = false;
          self.serialPoller.close();
        }

        if (callback) {
          callback();
        }
      });
    } catch (ex) {
      self.closing = false;
      if (callback) {
        callback(ex);
      } else {
        self.emit('error', ex);
      }
    }
  };

  function listUnix(callback) {
    fs.readdir("/dev/serial/by-id", function (err, files) {
      if (err) {
        // if this directory is not found this could just be because it's not plugged in
        if (err.errno === 34) {
          return callback(null, []);
        }

        if (callback) {
          callback(err);
        } else {
          factory.emit('error', err);
        }
        return;
      }

      var dirName = "/dev/serial/by-id";
      async.map(files, function (file, callback) {
        var fileName = path.join(dirName, file);
        fs.readlink(fileName, function (err, link) {
          if (err) {
            if (callback) {
              callback(err);
            } else {
              factory.emit('error', err);
            }
            return;
          }

          link = path.resolve(dirName, link);
          callback(null, {
            comName: link,
            manufacturer: undefined,
            pnpId: file
          });
        });
      }, callback);
    });
  }

  SerialPort.prototype.flush = function (callback) {
    var self = this;
    var fd = self.fd;

    if (!fd) {
      var err = new Error("Serialport not open.");
      if (callback) {
        callback(err);
      } else {
        self.emit('error', err);
      }
      return;
    }

    factory.SerialPortBinding.flush(fd, function (err, result) {
      if (err) {
        if (callback) {
          callback(err, result);
        } else {
          self.emit('error', err);
        }
      } else {
        callback(err, result);
      }
    });
  };

  SerialPort.prototype.drain = function (callback) {
    var self = this;
    var fd = this.fd;

    if (!fd) {
      var err = new Error("Serialport not open.");
      if (callback) {
        callback(err);
      } else {
        self.emit('error', err);
      }
      return;
    }

    factory.SerialPortBinding.drain(fd, function (err, result) {
      if (err) {
        if (callback) {
          callback(err, result);
        } else {
          self.emit('error', err);
        }
      } else {
        callback(err, result);
      }
    });
  };

  factory.SerialPort = SerialPort;
  factory.parsers = parsers;
  factory.SerialPortBinding = SerialPortBinding;

  if (process.platform === 'win32') {
    factory.list = SerialPortBinding.list;
  } else if (process.platform === 'darwin') {
    factory.list = SerialPortBinding.list;
  } else {
    factory.list = listUnix;
  }

}

util.inherits(SerialPortFactory, EventEmitter);

module.exports = new SerialPortFactory();