Fix minor issue in UTF-32 decoder.

In streaming mode, if the first chunk is < 32 bytes, but there are more
chunks written with total size of the stream > 32 bytes, then we were
losing initial chunk. This looks like an unlikely scenario, so not a
major issue.

Note, this is happening only in UTF-32 decoder, not UTF-32LE or BE,
as the problem was in the code that detects encoding.

Author: ashtuchkin

encodings/utf32.js

@@ -164,7 +164,7 @@ Utf32Decoder.prototype.end = function() {
 // Encoder prepends BOM (which can be overridden with (addBOM: false}).
 
 exports.utf32 = Utf32AutoCodec;
-exports.ucs4 = Utf32AutoCodec;
+exports.ucs4 = 'utf32';
 
 function Utf32AutoCodec(options, iconv) {
     this.iconv = iconv;
@@ -212,8 +212,8 @@ Utf32AutoDecoder.prototype.write = function(buf) {
             return '';
 
         // We have enough bytes -> detect endianness.
-        var buf2 = Buffer.concat(this.initialBytes),
-            encoding = detectEncoding(buf2, this.options.defaultEncoding);
+        var buf = Buffer.concat(this.initialBytes),
+            encoding = detectEncoding(buf, this.options.defaultEncoding);
         this.decoder = this.iconv.getDecoder(encoding, this.options);
         this.initialBytes.length = this.initialBytesLen = 0;
     }

test/streams-test.js

@@ -297,6 +297,15 @@ describe("Streaming mode", function() {
         input: [Buffer.from('&T2'), Buffer.from('BZf'), Buffer.from('Q hei&AN8-t')],
         output: '\u4F60\u597D heißt'
     }));
+
+    it("Decoding of chunks in UTF-32 auto mode does not lose chunks", checkDecodeStream({
+        encoding: "UTF-32",
+        input: [
+            [0x00, 0x00, 0x00, 0x61, 0x00, 0x00, 0x00, 0x62, 0x00, 0x00, 0x00, 0x63, 0x00, 0x00, 0x00, 0x64],
+            [0x00, 0x00, 0x00, 0x61, 0x00, 0x00, 0x00, 0x62, 0x00, 0x00, 0x00, 0x63, 0x00, 0x00, 0x00, 0x64],
+        ],
+        output: "abcdabcd",
+    }));
 });
 
 describe("Streaming sugar", function() {