Function exec2

imagemagick.js:5–98

(file, args /*, options, callback */)

function exec2(file, args /*, options, callback */) {
  var options = { encoding: 'utf8'
                , timeout: 0
                , maxBuffer: 500*1024
                , killSignal: 'SIGKILL'
                , output: null
                };

  var callback = arguments[arguments.length-1];
  if ('function' != typeof callback) callback = null;

  if (typeof arguments[2] == 'object') {
    var keys = Object.keys(options);
    for (var i = 0; i < keys.length; i++) {
      var k = keys[i];
      if (arguments[2][k] !== undefined) options[k] = arguments[2][k];
    }
  }

  var child = childproc.spawn(file, args);
  var killed = false;
  var timedOut = false;

  var Wrapper = function(proc) {
    this.proc = proc;
    this.stderr = new Accumulator();
    proc.emitter = new EventEmitter();
    proc.on = proc.emitter.on.bind(proc.emitter);
    this.out = proc.emitter.emit.bind(proc.emitter, 'data');
    this.err = this.stderr.out.bind(this.stderr);
    this.errCurrent = this.stderr.current.bind(this.stderr);
  };
  Wrapper.prototype.finish = function(err) {
    this.proc.emitter.emit('end', err, this.errCurrent());
  };

  var Accumulator = function(cb) {
    this.stdout = {contents: ""};
    this.stderr = {contents: ""};
    this.callback = cb;

    var limitedWrite = function(stream) {
      return function(chunk) {
        stream.contents += chunk;
        if (!killed && stream.contents.length > options.maxBuffer) {
          child.kill(options.killSignal);
          killed = true;
        }
      };
    };
    this.out = limitedWrite(this.stdout);
    this.err = limitedWrite(this.stderr);
  };
  Accumulator.prototype.current = function() { return this.stdout.contents; };
  Accumulator.prototype.errCurrent = function() { return this.stderr.contents; };
  Accumulator.prototype.finish = function(err) { this.callback(err, this.stdout.contents, this.stderr.contents); };

  var std = callback ? new Accumulator(callback) : new Wrapper(child);