Fixed ungzip: force window size when not set, because autodetect impossible

lib/inflate.js

@@ -100,6 +100,16 @@ var Inflate = function(options) {
     opt.windowBits += 32;
   }
 
+  // Gzip header has no info about windows size, we can do autodetect only
+  // for deflate. So, if window size not set, force it to max when gzip possible
+  if ((opt.windowBits > 15) && (opt.windowBits < 48)) {
+    // bit 3 (16) -> gzipped data
+    // bit 4 (32) -> autodetect gzip/deflate
+    if ((opt.windowBits & 15) === 0) {
+      opt.windowBits |= 15;
+    }
+  }
+
   this.err    = 0;      // error code, if happens (0 = Z_OK)
   this.msg    = '';     // error message
   this.ended  = false;  // used to avoid multiple onEnd() calls

test/inflate.js

@@ -28,12 +28,12 @@ describe('Inflate ungzip', function () {
   // TODO: Investigate, why ungzip does not autodetect window size and
   // require to set windowBits directly
 
-  it.skip('with autodetect', function(done) {
+  it('with autodetect', function(done) {
     testInflate(samples, {}, { gzip: true }, done);
   });
 
   it('with method set directly', function(done) {
-    testInflate(samples, { windowBits: 15 + 16 }, { gzip: true }, done);
+    testInflate(samples, { windowBits: 16 }, { gzip: true }, done);
   });
 });