zlib: revert back to Functions

Using ES6 Classes broke userland code. Revert back to functions.

PR-URL: https://github.com/nodejs/node/pull/13374
Fixes: https://github.com/nodejs/node/issues/13358
Ref: https://github.com/nodejs/node/pull/13370
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/zlib.js

@@ -22,7 +22,6 @@
 'use strict';
 
 const Buffer = require('buffer').Buffer;
-const internalUtil = require('internal/util');
 const Transform = require('_stream_transform');
 const binding = process.binding('zlib');
 const assert = require('assert').ok;
@@ -31,7 +30,7 @@ const kRangeErrorMessage = 'Cannot create final Buffer. It would be larger ' +
                            `than 0x${kMaxLength.toString(16)} bytes`;
 
 const constants = process.binding('constants').zlib;
-const createClassWrapper = internalUtil.createClassWrapper;
+const { inherits } = require('util');
 
 // translation table for return codes.
 const codes = {
@@ -170,10 +169,9 @@ function flushCallback(level, strategy, callback) {
 // This thing manages the queue of requests, and returns
 // true or false if there is anything in the queue when
 // you call the .write() method.
-class Zlib extends Transform {
+function Zlib(opts, mode) {
-  constructor(opts, mode) {
   opts = opts || {};
-    super(opts);
+  Transform.call(this, opts);
 
   this.bytesRead = 0;
 
@@ -265,12 +263,17 @@ class Zlib extends Transform {
 
   this.once('end', this.close);
 }
+inherits(Zlib, Transform);
 
-  get _closed() {
+Object.defineProperty(Zlib.prototype, '_closed', {
+  configurable: true,
+  enumerable: true,
+  get() {
     return !this._handle;
   }
+});
 
-  params(level, strategy, callback) {
+Zlib.prototype.params = function params(level, strategy, callback) {
   if (level < constants.Z_MIN_LEVEL ||
       level > constants.Z_MAX_LEVEL) {
     throw new RangeError('Invalid compression level: ' + level);
@@ -284,20 +287,20 @@ class Zlib extends Transform {
   } else {
     process.nextTick(callback);
   }
-  }
+};
 
-  reset() {
+Zlib.prototype.reset = function reset() {
   assert(this._handle, 'zlib binding closed');
   return this._handle.reset();
-  }
+};
 
 // This is the _flush function called by the transform class,
 // internally, when the last chunk has been written.
-  _flush(callback) {
+Zlib.prototype._flush = function _flush(callback) {
   this._transform(Buffer.alloc(0), '', callback);
-  }
+};
 
-  flush(kind, callback) {
+Zlib.prototype.flush = function flush(kind, callback) {
   var ws = this._writableState;
 
   if (typeof kind === 'function' || (kind === undefined && !callback)) {
@@ -320,14 +323,14 @@ class Zlib extends Transform {
     this._flushFlag = kind;
     this.write(Buffer.alloc(0), '', callback);
   }
-  }
+};
 
-  close(callback) {
+Zlib.prototype.close = function close(callback) {
   _close(this, callback);
   process.nextTick(emitCloseNT, this);
-  }
+};
 
-  _transform(chunk, encoding, cb) {
+Zlib.prototype._transform = function _transform(chunk, encoding, cb) {
   var flushFlag;
   var ws = this._writableState;
   var ending = ws.ending || ws.ended;
@@ -356,9 +359,9 @@ class Zlib extends Transform {
   }
 
   this._processChunk(chunk, flushFlag, cb);
-  }
+};
 
-  _processChunk(chunk, flushFlag, cb) {
+Zlib.prototype._processChunk = function _processChunk(chunk, flushFlag, cb) {
   var availInBefore = chunk && chunk.byteLength;
   var availOutBefore = this._chunkSize - this._offset;
   var inOff = 0;
@@ -481,8 +484,7 @@ class Zlib extends Transform {
     // finished with the chunk.
     cb();
   }
-  }
+};
-}
 
 function _close(engine, callback) {
   if (callback)
@@ -502,47 +504,54 @@ function emitCloseNT(self) {
 
 // generic zlib
 // minimal 2-byte header
-class Deflate extends Zlib {
+function Deflate(opts) {
-  constructor(opts) {
+  if (!(this instanceof Deflate))
-    super(opts, constants.DEFLATE);
+    return new Deflate(opts);
-  }
+  Zlib.call(this, opts, constants.DEFLATE);
 }
+inherits(Deflate, Zlib);
 
-class Inflate extends Zlib {
+function Inflate(opts) {
-  constructor(opts) {
+  if (!(this instanceof Inflate))
-    super(opts, constants.INFLATE);
+    return new Inflate(opts);
-  }
+  Zlib.call(this, opts, constants.INFLATE);
 }
+inherits(Inflate, Zlib);
 
-class Gzip extends Zlib {
+function Gzip(opts) {
-  constructor(opts) {
+  if (!(this instanceof Gzip))
-    super(opts, constants.GZIP);
+    return new Gzip(opts);
-  }
+  Zlib.call(this, opts, constants.GZIP);
 }
+inherits(Gzip, Zlib);
 
-class Gunzip extends Zlib {
+function Gunzip(opts) {
-  constructor(opts) {
+  if (!(this instanceof Gunzip))
-    super(opts, constants.GUNZIP);
+    return new Gunzip(opts);
-  }
+  Zlib.call(this, opts, constants.GUNZIP);
 }
+inherits(Gunzip, Zlib);
 
-class DeflateRaw extends Zlib {
+function DeflateRaw(opts) {
-  constructor(opts) {
+  if (!(this instanceof DeflateRaw))
-    super(opts, constants.DEFLATERAW);
+    return new DeflateRaw(opts);
-  }
+  Zlib.call(this, opts, constants.DEFLATERAW);
 }
+inherits(DeflateRaw, Zlib);
 
-class InflateRaw extends Zlib {
+function InflateRaw(opts) {
-  constructor(opts) {
+  if (!(this instanceof InflateRaw))
-    super(opts, constants.INFLATERAW);
+    return new InflateRaw(opts);
-  }
+  Zlib.call(this, opts, constants.INFLATERAW);
 }
+inherits(InflateRaw, Zlib);
 
-class Unzip extends Zlib {
+function Unzip(opts) {
-  constructor(opts) {
+  if (!(this instanceof Unzip))
-    super(opts, constants.UNZIP);
+    return new Unzip(opts);
-  }
+  Zlib.call(this, opts, constants.UNZIP);
 }
+inherits(Unzip, Zlib);
 
 function createConvenienceMethod(type, sync) {
   if (sync) {
@@ -569,13 +578,13 @@ function createProperty(type) {
 }
 
 module.exports = {
-  Deflate: createClassWrapper(Deflate),
+  Deflate,
-  Inflate: createClassWrapper(Inflate),
+  Inflate,
-  Gzip: createClassWrapper(Gzip),
+  Gzip,
-  Gunzip: createClassWrapper(Gunzip),
+  Gunzip,
-  DeflateRaw: createClassWrapper(DeflateRaw),
+  DeflateRaw,
-  InflateRaw: createClassWrapper(InflateRaw),
+  InflateRaw,
-  Unzip: createClassWrapper(Unzip),
+  Unzip,
 
   // Convenience methods.
   // compress/decompress a string or buffer in one step.

test/parallel/test-zlib-deflate-raw-inherits.js

@@ -0,0 +1,27 @@
+'use strict';
+
+require('../common');
+const { DeflateRaw } = require('zlib');
+const { inherits } = require('util');
+const { Readable } = require('stream');
+
+// validates that zlib.DeflateRaw can be inherited
+// with util.inherits
+
+function NotInitialized(options) {
+  DeflateRaw.call(this, options);
+  this.prop = true;
+}
+inherits(NotInitialized, DeflateRaw);
+
+const dest = new NotInitialized();
+
+const read = new Readable({
+  read() {
+    this.push(Buffer.from('a test string'));
+    this.push(null);
+  }
+});
+
+read.pipe(dest);
+dest.resume();