This file is indexed.

/usr/lib/nodejs/fd-slicer/index.js is in node-fd-slicer 0.3.2-1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

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var fs = require('fs');
var util = require('util');
var stream = require('stream');
var Readable = stream.Readable;
var Writable = stream.Writable;
var Pend = require('pend');
var EventEmitter = require('events').EventEmitter;

module.exports = FdSlicer;

util.inherits(FdSlicer, EventEmitter);
function FdSlicer(fd, options) {
  options = options || {};
  EventEmitter.call(this);

  this.fd = fd;
  this.pend = new Pend();
  this.pend.max = 1;
  this.refCount = 0;
  this.autoClose = !!options.autoClose;
}

FdSlicer.prototype.read = function(buffer, offset, length, position, callback) {
  var self = this;
  self.pend.go(function(cb) {
    fs.read(self.fd, buffer, offset, length, position, function(err, bytesRead, buffer) {
      cb();
      callback(err, bytesRead, buffer);
    });
  });
};

FdSlicer.prototype.write = function(buffer, offset, length, position, callback) {
  var self = this;
  self.pend.go(function(cb) {
    fs.write(self.fd, buffer, offset, length, position, function(err, written, buffer) {
      cb();
      callback(err, written, buffer);
    });
  });
};

FdSlicer.prototype.createReadStream = function(options) {
  return new ReadStream(this, options);
};

FdSlicer.prototype.createWriteStream = function(options) {
  return new WriteStream(this, options);
};

FdSlicer.prototype.ref = function() {
  this.refCount += 1;
};

FdSlicer.prototype.unref = function() {
  var self = this;
  self.refCount -= 1;

  if (self.refCount > 0) return;
  if (self.refCount < 0) throw new Error("invalid unref");

  if (self.autoClose) {
    fs.close(self.fd, onCloseDone);
  }

  function onCloseDone(err) {
    if (err) {
      self.emit('error', err);
    } else {
      self.emit('close');
    }
  }
};

util.inherits(ReadStream, Readable);
function ReadStream(context, options) {
  options = options || {};
  Readable.call(this, options);

  this.context = context;
  this.context.ref();

  this.start = options.start || 0;
  this.end = options.end;
  this.pos = this.start;
  this.destroyed = false;
}

ReadStream.prototype._read = function(n) {
  var self = this;
  if (self.destroyed) return;

  var toRead = Math.min(self._readableState.highWaterMark, n);
  if (self.end != null) {
    toRead = Math.min(toRead, self.end - self.pos);
  }
  if (toRead <= 0) {
    self.destroyed = true;
    self.push(null);
    self.context.unref();
    return;
  }
  self.context.pend.go(function(cb) {
    if (self.destroyed) return cb();
    var buffer = new Buffer(toRead);
    fs.read(self.context.fd, buffer, 0, toRead, self.pos, function(err, bytesRead) {
      if (err) {
        self.destroy(err);
      } else if (bytesRead === 0) {
        self.destroyed = true;
        self.push(null);
        self.context.unref();
      } else {
        self.pos += bytesRead;
        self.push(buffer.slice(0, bytesRead));
      }
      cb();
    });
  });
};

ReadStream.prototype.destroy = function(err) {
  if (this.destroyed) return;
  err = err || new Error("stream destroyed");
  this.destroyed = true;
  this.emit('error', err);
  this.context.unref();
};

util.inherits(WriteStream, Writable);
function WriteStream(context, options) {
  options = options || {};
  Writable.call(this, options);

  this.context = context;
  this.context.ref();

  this.start = options.start || 0;
  this.endOffset = options.end || Infinity;
  this.bytesWritten = 0;
  this.pos = this.start;
  this.destroyed = false;

  this.on('finish', this.destroy.bind(this));
}

WriteStream.prototype._write = function(buffer, encoding, callback) {
  var self = this;
  if (self.destroyed) return;

  if (self.pos + buffer.length > self.endOffset) {
    var err = new Error("maximum file length exceeded");
    err.code = 'ETOOBIG';
    self.destroy();
    callback(err);
    return;
  }
  self.context.pend.go(function(cb) {
    if (self.destroyed) return cb();
    fs.write(self.context.fd, buffer, 0, buffer.length, self.pos, function(err, bytes) {
      if (err) {
        self.destroy();
        cb();
        callback(err);
      } else {
        self.bytesWritten += bytes;
        self.pos += bytes;
        self.emit('progress');
        cb();
        callback();
      }
    });
  });
};

WriteStream.prototype.destroy = function() {
  if (this.destroyed) return;
  this.destroyed = true;
  this.context.unref();
};