gistfile1.diff

diff --git a/lib/zlib.js b/lib/zlib.js
index f80c983..998f14f 100644
--- a/lib/zlib.js
+++ b/lib/zlib.js
@@ -297,7 +297,7 @@ function Zlib(opts, mode) {
 
   Transform.call(this, opts);
 
-  if (opts.flush) {
+  if (opts.hasOwnProperty('flush')) {
     if (opts.flush !== binding.Z_NO_FLUSH &&
         opts.flush !== binding.Z_PARTIAL_FLUSH &&
         opts.flush !== binding.Z_SYNC_FLUSH &&
@@ -309,35 +309,43 @@ function Zlib(opts, mode) {
   }
   this._flushFlag = opts.flush || binding.Z_NO_FLUSH;
 
-  if (opts.chunkSize) {
+  if (opts.hasOwnProperty('chunkSize')) {
     if (opts.chunkSize < exports.Z_MIN_CHUNK ||
         opts.chunkSize > exports.Z_MAX_CHUNK) {
       throw new Error('Invalid chunk size: ' + opts.chunkSize);
     }
   }
 
-  if (opts.windowBits) {
-    if (opts.windowBits < exports.Z_MIN_WINDOWBITS ||
-        opts.windowBits > exports.Z_MAX_WINDOWBITS) {
-      throw new Error('Invalid windowBits: ' + opts.windowBits);
+  if (opts.hasOwnProperty('windowBits')) {
+    // In inflate mode, windowBits is allowed to be 0, which indicates that windowBits should be based on the sender's zlib header.
+    if (mode === binding.INFLATE || mode === binding.INFLATERAW || mode === binding.UNZIP || mode === binding.GUNZIP) {
+      if (opts.windowBits !== 0 && (opts.windowBits < exports.Z_MIN_WINDOWBITS || opts.windowBits > exports.Z_MAX_WINDOWBITS) {
+        throw new Error('Invalid windowBits: ' + opts.windowBits);
+      }
+    }
+    // In deflate mode, windowBits is not allowed to be 0.
+    else {
+      if (opts.windowBits < exports.Z_MIN_WINDOWBITS || opts.windowBits > exports.Z_MAX_WINDOWBITS) {
+        throw new Error('Invalid windowBits: ' + opts.windowBits);
+      }
     }
   }
 
-  if (opts.level) {
+  if (opts.hasOwnProperty('level')) {
     if (opts.level < exports.Z_MIN_LEVEL ||
         opts.level > exports.Z_MAX_LEVEL) {
       throw new Error('Invalid compression level: ' + opts.level);
     }
   }
 
-  if (opts.memLevel) {
+  if (opts.hasOwnProperty('memLevel')) {
     if (opts.memLevel < exports.Z_MIN_MEMLEVEL ||
         opts.memLevel > exports.Z_MAX_MEMLEVEL) {
       throw new Error('Invalid memLevel: ' + opts.memLevel);
     }
   }
 
-  if (opts.strategy) {
+  if (opts.hasOwnProperty('strategy')) {
     if (opts.strategy != exports.Z_FILTERED &&
         opts.strategy != exports.Z_HUFFMAN_ONLY &&
         opts.strategy != exports.Z_RLE &&
@@ -375,7 +383,19 @@ function Zlib(opts, mode) {
   var strategy = exports.Z_DEFAULT_STRATEGY;
   if (util.isNumber(opts.strategy)) strategy = opts.strategy;
 
-  this._handle.init(opts.windowBits || exports.Z_DEFAULT_WINDOWBITS,
+  // In inflate mode, windowBits is allowed to be 0, which indicates that windowBits should be based on the sender's zlib header.
+  var windowBits = 0;
+  if (mode === binding.INFLATE || mode === binding.INFLATERAW || mode === binding.UNZIP || mode === binding.GUNZIP) {
+    if (opts.windowBits !== 0) {
+        windowBits = opts.windowBits || exports.Z_DEFAULT_WINDOWBITS;
+    }
+  }
+  // In deflate mode, windowBits is not allowed to be 0.
+  else {
+    windowBits = opts.windowBits || exports.Z_DEFAULT_WINDOWBITS;
+  }
+
+  this._handle.init(windowBits,
                     level,
                     opts.memLevel || exports.Z_DEFAULT_MEMLEVEL,
                     strategy,
diff --git a/src/node_zlib.cc b/src/node_zlib.cc
index 0904c88..81b97fa 100644
--- a/src/node_zlib.cc
+++ b/src/node_zlib.cc
@@ -397,7 +397,7 @@ class ZCtx : public AsyncWrap {
     ZCtx* ctx = Unwrap<ZCtx>(args.Holder());
 
     int windowBits = args[0]->Uint32Value();
-    assert((windowBits >= 8 && windowBits <= 15) && "invalid windowBits");
+    assert((((ctx->mode_ == GUNZIP || ctx->mode_ == UNZIP || ctx->mode_ == INFLATE || ctx->mode_ == INFLATERAW) && windowBits === 0) || (windowBits >= 8 && windowBits <= 15)) && "invalid windowBits");
 
     int level = args[1]->Int32Value();
     assert((level >= -1 && level <= 9) && "invalid compression level");
@@ -423,8 +423,7 @@ class ZCtx : public AsyncWrap {
       memcpy(dictionary, Buffer::Data(dictionary_), dictionary_len);
     }
 
-    Init(ctx, level, windowBits, memLevel, strategy,
-         dictionary, dictionary_len);
+    Init(ctx, level, windowBits, memLevel, strategy, dictionary, dictionary_len);
     SetDictionary(ctx);
   }