Add code to inspect any file and classify its format

openrct2.vcxproj

@@ -88,6 +88,7 @@
     <None Include="openrct2.exe" />
   </ItemGroup>
   <ItemGroup>
+    <ClCompile Include="src\FileClassifier.cpp" />
     <ClCompile Include="src\rct2\addresses.c" />
     <ClCompile Include="src\audio\audio.c" />
     <ClCompile Include="src\audio\mixer.cpp" />
@@ -422,6 +423,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="resources\resource.h" />
+    <ClInclude Include="src\FileClassifier.h" />
     <ClInclude Include="src\rct2\addresses.h" />
     <ClInclude Include="src\audio\audio.h" />
     <ClInclude Include="src\audio\mixer.h" />

src/FileClassifier.cpp

@@ -0,0 +1,175 @@
+#pragma region Copyright (c) 2014-2016 OpenRCT2 Developers
+/*****************************************************************************
+ * OpenRCT2, an open source clone of Roller Coaster Tycoon 2.
+ *
+ * OpenRCT2 is the work of many authors, a full list can be found in contributors.md
+ * For more information, visit https://github.com/OpenRCT2/OpenRCT2
+ *
+ * OpenRCT2 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * A full copy of the GNU General Public License can be found in licence.txt
+ *****************************************************************************/
+#pragma endregion
+
+#include "core/FileStream.hpp"
+#include "FileClassifier.h"
+
+extern "C"
+{
+    #include "scenario/scenario.h"
+    #include "util/sawyercoding.h"
+}
+
+static bool TryClassifyAsS6(IStream * stream, ClassifiedFile * result);
+static bool TryClassifyAsS4(IStream * stream, ClassifiedFile * result);
+static bool TryClassifyAsTD4_TD6(IStream * stream, ClassifiedFile * result);
+static bool sawyercoding_try_read_chunk(void * dst, size_t expectedSize, IStream * stream);
+
+bool TryClassifyFile(const std::string &path, ClassifiedFile * result)
+{
+    try
+    {
+        auto fs = FileStream(path, FILE_MODE_OPEN);
+        return TryClassifyFile(&fs, result);
+    }
+    catch (Exception)
+    {
+        return false;
+    }
+}
+
+bool TryClassifyFile(IStream * stream, ClassifiedFile * result)
+{
+    // TODO Currently track designs get classified as SC4s because they use the
+    //      same checksum algorithm. The only way after to tell the difference
+    //      between them is to decode it. Decoding however is currently not protected
+    //      against invalid compression data for that decoding algorithm and will crash.
+
+    // S6 detection
+    if (TryClassifyAsS6(stream, result))
+    {
+        return true;
+    }
+
+    // S4 detection
+    if (TryClassifyAsS4(stream, result))
+    {
+        return true;
+    }
+
+    // TD6 detection
+    if (TryClassifyAsTD4_TD6(stream, result))
+    {
+        return true;
+    }
+
+    return false;
+}
+
+static bool TryClassifyAsS6(IStream * stream, ClassifiedFile * result)
+{
+    rct_s6_header s6Header;
+    if (sawyercoding_try_read_chunk(&s6Header, sizeof(rct_s6_header), stream))
+    {
+        if (s6Header.type == S6_TYPE_SAVEDGAME)
+        {
+            result->Type = FILE_TYPE::SAVED_GAME;
+        }
+        else if (s6Header.type == S6_TYPE_SCENARIO)
+        {
+            result->Type = FILE_TYPE::SCENARIO;
+        }
+        result->Version = s6Header.version;
+        return true;
+    }
+
+    return false;
+}
+
+static bool TryClassifyAsS4(IStream * stream, ClassifiedFile * result)
+{
+    uint64 originalPosition = stream->GetPosition();
+    size_t dataLength = (size_t)stream->GetLength();
+    uint8 * data = stream->ReadArray<uint8>(dataLength);
+    stream->SetPosition(originalPosition);
+    int fileTypeVersion = sawyercoding_detect_file_type(data, dataLength);
+    Memory::Free(data);
+
+    int type = fileTypeVersion & FILE_TYPE_MASK;
+    int version = fileTypeVersion & FILE_VERSION_MASK;
+
+    if (type == FILE_TYPE_SV4)
+    {
+        result->Type = FILE_TYPE::SAVED_GAME;
+        result->Version = version;
+        return true;
+    }
+    else if (type == FILE_TYPE_SC4)
+    {
+        result->Type = FILE_TYPE::SCENARIO;
+        result->Version = version;
+        return true;
+    }
+    
+    return false;
+}
+
+static bool TryClassifyAsTD4_TD6(IStream * stream, ClassifiedFile * result)
+{
+    bool success = false;
+    uint64 originalPosition = stream->GetPosition();
+    size_t dataLength = (size_t)stream->GetLength();
+    uint8 * data = stream->ReadArray<uint8>(dataLength);
+    stream->SetPosition(originalPosition);
+
+    if (sawyercoding_validate_track_checksum(data, dataLength))
+    {
+        uint8 * td6data = Memory::Allocate<uint8>(0x10000);
+        size_t td6len = sawyercoding_decode_td6(data, td6data, dataLength);
+        if (td6data != nullptr && td6len >= 8)
+        {
+            uint8 version = (td6data[7] >> 2) & 3;
+            if (version <= 2)
+            {
+                result->Type = FILE_TYPE::TRACK_DESIGN;
+                result->Version = version;
+                success = true;
+            }
+        }
+        Memory::Free(td6data);
+    }
+    Memory::Free(data);
+
+    return success;
+}
+
+static bool sawyercoding_try_read_chunk(void * dst, size_t expectedSize, IStream * stream)
+{
+    uint64 originalPosition = stream->GetPosition();
+
+    bool success = false;
+    auto header = stream->ReadValue<sawyercoding_chunk_header>();
+    switch (header.encoding) {
+    case CHUNK_ENCODING_NONE:
+    case CHUNK_ENCODING_RLE:
+    case CHUNK_ENCODING_RLECOMPRESSED:
+    case CHUNK_ENCODING_ROTATE:
+        uint8 * compressedData = Memory::Allocate<uint8>(header.length);
+        if (stream->TryRead(compressedData, header.length) == header.length)
+        {
+            size_t uncompressedLength = sawyercoding_read_chunk_buffer((uint8 *)dst, compressedData, header, expectedSize);
+            if (uncompressedLength == expectedSize)
+            {
+                success = true;
+            }
+        }
+        Memory::Free(compressedData);
+        break;
+    }
+
+    stream->SetPosition(originalPosition);
+    return success;
+}

src/FileClassifier.h

@@ -0,0 +1,40 @@
+#pragma region Copyright (c) 2014-2016 OpenRCT2 Developers
+/*****************************************************************************
+ * OpenRCT2, an open source clone of Roller Coaster Tycoon 2.
+ *
+ * OpenRCT2 is the work of many authors, a full list can be found in contributors.md
+ * For more information, visit https://github.com/OpenRCT2/OpenRCT2
+ *
+ * OpenRCT2 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * A full copy of the GNU General Public License can be found in licence.txt
+ *****************************************************************************/
+#pragma endregion
+
+#pragma once
+
+#include <string>
+#include "common.h"
+
+interface IStream;
+
+enum class FILE_TYPE
+{
+    UNDEFINED,
+    OBJECT,
+    SAVED_GAME,
+    SCENARIO,
+    TRACK_DESIGN,
+};
+
+struct ClassifiedFile
+{
+    FILE_TYPE Type;
+    uint32    Version;
+};
+
+bool TryClassifyFile(const std::string &path, ClassifiedFile * result);
+bool TryClassifyFile(IStream * stream, ClassifiedFile * result);