zlib: fix node crashing on invalid options

doc/api/zlib.md

@@ -437,6 +437,10 @@ added: v0.5.8
 
 Returns a new [DeflateRaw][] object with an [options][].
 
+**Note:** zlib library rejects requests for 256-byte windows (i.e.,
+`{ windowBits: 8 }` in `options`). An `Error` will be thrown when creating
+a [DeflateRaw][] object with this specific value of the `windowBits` option.
+
 ## zlib.createGunzip([options])
 <!-- YAML
 added: v0.5.8

lib/zlib.js

@@ -229,9 +229,15 @@ class Zlib extends Transform {
     var strategy = constants.Z_DEFAULT_STRATEGY;
     if (typeof opts.strategy === 'number') strategy = opts.strategy;
 
-    this._handle.init(opts.windowBits || constants.Z_DEFAULT_WINDOWBITS,
+    var windowBits = constants.Z_DEFAULT_WINDOWBITS;
+    if (typeof opts.windowBits === 'number') windowBits = opts.windowBits;
+
+    var memLevel = constants.Z_DEFAULT_MEMLEVEL;
+    if (typeof opts.memLevel === 'number') memLevel = opts.memLevel;
+
+    this._handle.init(windowBits,
                       level,
-                      opts.memLevel || constants.Z_DEFAULT_MEMLEVEL,
+                      memLevel,
                       strategy,
                       opts.dictionary);
 

src/node_zlib.cc

@@ -551,16 +551,19 @@ class ZCtx : public AsyncWrap {
         CHECK(0 && "wtf?");
     }
 
-    if (ctx->err_ != Z_OK) {
-      ZCtx::Error(ctx, "Init error");
-    }
-
-
     ctx->dictionary_ = reinterpret_cast<Bytef *>(dictionary);
     ctx->dictionary_len_ = dictionary_len;
 
     ctx->write_in_progress_ = false;
     ctx->init_done_ = true;
+
+    if (ctx->err_ != Z_OK) {
+      if (dictionary != nullptr) {
+        delete[] dictionary;
+        ctx->dictionary_ = nullptr;
+      }
+      ctx->env()->ThrowError("Init error");
+    }
   }
 
   static void SetDictionary(ZCtx* ctx) {

test/parallel/test-zlib-failed-init.js

@@ -0,0 +1,13 @@
+'use strict';
+
+require('../common');
+
+const assert = require('assert');
+const zlib = require('zlib');
+
+// For raw deflate encoding, requests for 256-byte windows are rejected as
+// invalid by zlib.
+// (http://zlib.net/manual.html#Advanced)
+assert.throws(() => {
+  zlib.createDeflateRaw({ windowBits: 8 });
+}, /Init error/);