COMMON: Move InstallShield code to common

The code also now works for both data compressed with sync bytes and without

1 files changed, 54 insertions, 0 deletions

diff --git a/common/zlib.cpp b/common/zlib.cpp
index 7d765fc539..98f319f351 100644
--- a/common/zlib.cpp
+++ b/common/zlib.cpp
@@ -85,6 +85,60 @@ bool inflateZlibHeaderless(byte *dst, uint dstLen, const byte *src, uint srcLen,
 	return true;
 }
 
+enum {
+	kTempBufSize = 65536
+};
+
+bool inflateZlibInstallShield(byte *dst, uint dstLen, const byte *src, uint srcLen) {
+	if (!dst || !dstLen || !src || !srcLen)
+		return false;
+
+	// See if we have sync bytes. If so, just use our function for that.
+	if (srcLen >= 4 && READ_BE_UINT32(src + srcLen - 4) == 0xFFFF)
+		return inflateZlibHeaderless(dst, dstLen, src, srcLen);
+
+	// Otherwise, we have some custom code we get to use here.
+
+	byte *temp = (byte *)malloc(kTempBufSize);
+
+	uint32 bytesRead = 0, bytesProcessed = 0;
+	while (bytesRead < srcLen) {
+		uint16 chunkSize = READ_LE_UINT16(src + bytesRead);
+		bytesRead += 2;
+
+		// Initialize zlib
+		z_stream stream;
+		stream.next_in = const_cast<byte *>(src + bytesRead);
+		stream.avail_in = chunkSize;
+		stream.next_out = temp;
+		stream.avail_out = kTempBufSize;
+		stream.zalloc = Z_NULL;
+		stream.zfree = Z_NULL;
+		stream.opaque = Z_NULL;
+
+		// Negative MAX_WBITS tells zlib there's no zlib header
+		int err = inflateInit2(&stream, -MAX_WBITS);
+		if (err != Z_OK)
+			return false;
+
+		err = inflate(&stream, Z_FINISH);
+		if (err != Z_OK && err != Z_STREAM_END) {
+			inflateEnd(&stream);
+			free(temp);
+			return false;
+		}
+
+		memcpy(dst + bytesProcessed, temp, stream.total_out);
+		bytesProcessed += stream.total_out;
+
+		inflateEnd(&stream);
+		bytesRead += chunkSize;
+	}
+
+	free(temp);
+	return true;
+}
+
 /**
  * A simple wrapper class which can be used to wrap around an arbitrary
  * other SeekableReadStream and will then provide on-the-fly decompression support.