GH-1227 add GZip compress function and a unit test fo GZip

logic/GZip.cpp

@@ -2,12 +2,6 @@
 #include <zlib.h>
 #include <QByteArray>
 
-// HACK: workaround for terrible macro crap on Windows
-int wrap_inflate (z_streamp strm, int flush)
-{
-	return inflate(strm, flush);
-}
-
 bool GZip::decompress(const QByteArray &compressedBytes, QByteArray &uncompressedBytes)
 {
 	if (compressedBytes.size() == 0)
@@ -17,16 +11,13 @@ bool GZip::decompress(const QByteArray &compressedBytes, QByteArray &uncompresse
 	}
 
 	unsigned uncompLength = compressedBytes.size();
-	unsigned half_length = compressedBytes.size() / 2;
 	uncompressedBytes.clear();
 	uncompressedBytes.resize(uncompLength);
 
 	z_stream strm;
+	memset(&strm, 0, sizeof(strm));
 	strm.next_in = (Bytef *)compressedBytes.data();
 	strm.avail_in = compressedBytes.size();
-	strm.total_out = 0;
-	strm.zalloc = Z_NULL;
-	strm.zfree = Z_NULL;
 
 	bool done = false;
 
@@ -35,20 +26,22 @@ bool GZip::decompress(const QByteArray &compressedBytes, QByteArray &uncompresse
 		return false;
 	}
 
+	int err = Z_OK;
+
 	while (!done)
 	{
 		// If our output buffer is too small
 		if (strm.total_out >= uncompLength)
 		{
-			uncompressedBytes.resize(uncompLength + half_length);
-			uncompLength += half_length;
+			uncompressedBytes.resize(uncompLength * 2);
+			uncompLength *= 2;
 		}
 
 		strm.next_out = (Bytef *)(uncompressedBytes.data() + strm.total_out);
 		strm.avail_out = uncompLength - strm.total_out;
 
 		// Inflate another chunk.
-		int err = wrap_inflate(&strm, Z_SYNC_FLUSH);
+		err = inflate(&strm, Z_SYNC_FLUSH);
 		if (err == Z_STREAM_END)
 			done = true;
 		else if (err != Z_OK)
@@ -57,7 +50,7 @@ bool GZip::decompress(const QByteArray &compressedBytes, QByteArray &uncompresse
 		}
 	}
 
-	if (inflateEnd(&strm) != Z_OK)
+	if (inflateEnd(&strm) != Z_OK || !done)
 	{
 		return false;
 	}
@@ -65,3 +58,58 @@ bool GZip::decompress(const QByteArray &compressedBytes, QByteArray &uncompresse
 	uncompressedBytes.resize(strm.total_out);
 	return true;
 }
+
+bool GZip::compress(const QByteArray &uncompressedBytes, QByteArray &compressedBytes)
+{
+	if (uncompressedBytes.size() == 0)
+	{
+		compressedBytes = uncompressedBytes;
+		return true;
+	}
+
+	unsigned compLength = std::min(uncompressedBytes.size(), 16);
+	compressedBytes.clear();
+	compressedBytes.resize(compLength);
+
+	z_stream zs;
+	memset(&zs, 0, sizeof(zs));
+
+	if (deflateInit2(&zs, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (16 + MAX_WBITS), 8, Z_DEFAULT_STRATEGY) != Z_OK)
+	{
+		return false;
+	}
+
+	zs.next_in = (Bytef*)uncompressedBytes.data();
+	zs.avail_in = uncompressedBytes.size();
+
+	int ret;
+	compressedBytes.resize(uncompressedBytes.size());
+
+	unsigned offset = 0;
+	unsigned temp = 0;
+	do
+	{
+		auto remaining = compressedBytes.size() - offset;
+		if(remaining < 1)
+		{
+			compressedBytes.resize(compressedBytes.size() * 2);
+		}
+		zs.next_out = (Bytef *) (compressedBytes.data() + offset);
+		temp = zs.avail_out = compressedBytes.size() - offset;
+		ret = deflate(&zs, Z_FINISH);
+		offset += temp - zs.avail_out;
+	} while (ret == Z_OK);
+
+	compressedBytes.resize(offset);
+
+	if (deflateEnd(&zs) != Z_OK)
+	{
+		return false;
+	}
+
+	if (ret != Z_STREAM_END)
+	{
+		return false;
+	}
+	return true;
+}

logic/GZip.h

@@ -7,5 +7,6 @@ class MULTIMC_LOGIC_EXPORT GZip
 {
 public:
 	static bool decompress(const QByteArray &compressedBytes, QByteArray &uncompressedBytes);
+	static bool compress(const QByteArray &uncompressedBytes, QByteArray &compressedBytes);
 };