RPGMaker: Support RPG Maker VX Ace (closes #10)

CMakeLists.txt

@@ -26,7 +26,7 @@ find_package(ZLIB REQUIRED)
 find_path(ZSTR_INCLUDE_DIRS "zstr.hpp")
 
 set(ALL_MODULES renpy rpgmaker zanzarah)
-set(RELEASED_MODULES renpy zanzarah)
+set(RELEASED_MODULES renpy rpgmaker zanzarah)
 
 set(RENPY_DIR src/modules/renpy)
 add_library(renpy SHARED
@@ -55,6 +55,7 @@ add_executable(tests
         src/tests/framework/observer.cpp
         src/tests/framework/testcase.cpp
         src/tests/renpy.cpp
+        src/tests/rpgmaker.cpp
         src/tests/zanzarah.cpp
 )
 target_link_libraries(tests PRIVATE Catch2::Catch2WithMain)

README.md

@@ -18,9 +18,15 @@ specific files as needed without having to unpack the entire archive.
 - Compatibility: RPA-2.0, RPA-3.0
 - Description: Archives used in Ren'Py visual novels to store game resources (graphics, sound, scripts)
 
+### RPG Maker
+
+- Supported extensions: `.rgss3a`
+- Compatibility: RPG Maker VX Ace (RGSS3)
+- Description: Encrypted archives containing game assets like graphics, audio, and data files
+
 ### Zanzarah: The Hidden Portal
 
-- Supported extension: `.pak`
+- Supported extensions: `.pak`
 - Compatibility: Supports archives from both the original game version and the Steam version
 - Description: Archive used to store all game resources
 

copy_dlls.cmd

@@ -1,5 +1,5 @@
 @echo off
-pushd %~dp0\build\%1
+pushd %~dp0build\%1
 set MODULES_DIR=%DEBUGFARHOME%\Plugins\Observer\modules
 copy /Y *.so %MODULES_DIR% || exit 1
 copy /Y *.pdb %MODULES_DIR%

src/archive.cpp

@@ -86,6 +86,7 @@ namespace archive
             throw read_error();
         }
 
+        uint32_t magic = file.magic;
         int64_t bytes_left = file.compressed_body_size_in_bytes;
         while (bytes_left > 0) {
             const auto chunk_size = static_cast<std::streamsize>(std::min(bytes_left, buffer_size));
@@ -96,8 +97,11 @@ namespace archive
                 throw read_error();
             }
 
+            buffer.resize(static_cast<size_t>(chunk_size));
+            magic = extractor_->decrypt(magic, buffer);
+
             try {
-                output.write(buffer.data(), chunk_size);
+                output.write(buffer.data(), buffer.size());
             } catch (std::ios_base::failure &) {
                 throw write_error();
             }

src/modules/extractor.h

@@ -47,15 +47,20 @@ namespace extractor
         int64_t offset;
         int64_t compressed_body_size_in_bytes;
         int64_t uncompressed_body_size_in_bytes;
+        uint32_t magic = 0;
     };
 
     class extractor
     {
     public:
+        virtual ~extractor() = default;
+
         static std::vector<std::byte> get_signature() noexcept;
 
         archive_info get_archive_info(const std::span<const std::byte> &data) noexcept;
 
         std::vector<std::unique_ptr<file> > list_files(std::ifstream &stream);
+
+        uint32_t decrypt(uint32_t magic, std::vector<char> &data) const;
     };
 }

src/modules/renpy/renpy.cpp

@@ -127,4 +127,9 @@ namespace extractor
         }
         return files;
     }
+
+    uint32_t extractor::decrypt(uint32_t magic, std::vector<char> &data) const
+    {
+        return magic;
+    }
 }

src/modules/rpgmaker/rpgmaker.cpp

@@ -25,12 +25,7 @@ namespace extractor
     // ReSharper disable once CppMemberFunctionMayBeStatic
     archive_info extractor::get_archive_info(const std::span<const std::byte> &data) noexcept // NOLINT(*-convert-member-functions-to-static)
     {
-        // TODO implement: RGSS => RPG Maker XP, 0xDEADCAFE, XOR => zlib
-        // TODO implement: RGSS2 => RPG Maker VX, 0xCAFEDEAD, XOR => zlib
-        // TODO RPG Maker MV
-        // TODO RPG Maker MZ
-        // TODO .rvdata, .rvdata2
-        return archive_info{L"RGSS3", L"DEFLATE", L"RPG Maker VX Ace"};
+        return archive_info{L"RGSS3", L"-", L"RPG Maker VX Ace"};
     }
 
     static uint32_t read_u32(std::ifstream &stream)
@@ -68,8 +63,39 @@ namespace extractor
             new_file->offset = offset;
             new_file->compressed_body_size_in_bytes = size;
             new_file->uncompressed_body_size_in_bytes = size;
+            new_file->magic = file_magic;
             files.push_back(std::move(new_file));
         }
         return files;
     }
+
+    static uint32_t advance_magic(uint32_t &magic)
+    {
+        const uint32_t old = magic;
+        magic = magic * 7 + 3;
+        return old;
+    }
+
+    // ReSharper disable once CppMemberFunctionMayBeStatic
+    uint32_t extractor::decrypt(uint32_t magic, std::vector<char> &data) const // NOLINT(*-convert-member-functions-to-static)
+    {
+        const size_t size = data.size();
+        size_t i = 0;
+
+        while (i + 4 <= size) {
+            uint32_t value;
+            std::memcpy(&value, &data[i], sizeof(value));
+            value ^= advance_magic(magic);
+            std::memcpy(&data[i], &value, sizeof(value));
+            i += 4;
+        }
+
+        while (i < size) {
+            const auto byte_value = static_cast<uint8_t>(magic >> (i % 4 * 8));
+            data[i] = static_cast<char>(static_cast<uint8_t>(data[i]) ^ byte_value);
+            ++i;
+        }
+
+        return magic;
+    }
 }

src/modules/zanzarah/zanzarah.cpp

@@ -87,4 +87,9 @@ namespace extractor
 
         return files;
     }
+
+    uint32_t extractor::decrypt(uint32_t magic, std::vector<char> &data) const
+    {
+        return magic;
+    }
 }

src/tests/framework/observer.cpp

@@ -2,7 +2,6 @@
 #include "../../api.h"
 
 #include <fstream>
-#include <iostream>
 
 #include <windows.h>
 #include <catch2/catch_test_macros.hpp>
@@ -143,6 +142,7 @@ namespace test
     observer::observer()
     {
         modules_.push_back(std::make_unique<c_module>("renpy.so"));
+        modules_.push_back(std::make_unique<c_module>("rpgmaker.so"));
         modules_.push_back(std::make_unique<c_module>("zanzarah.so"));
     }
 

src/tests/rpgmaker.cpp

@@ -0,0 +1,50 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "framework/testcase.h"
+
+using namespace test;
+
+TEST_CASE("rpgmaker: GirlsXLust_v1.0")
+{
+    test_on("rpgmaker\\GirlsXLust_v1.0.rgss3a");
+}
+
+TEST_CASE("rpgmaker: Maid-X-Demon-Mari-s-First-Job")
+{
+    test_on("rpgmaker\\Maid-X-Demon-Mari-s-First-Job.rgss3a");
+}
+
+TEST_CASE("rpgmaker: MaiDensnow_Eve")
+{
+    test_on("rpgmaker\\MaiDensnow_Eve.rgss3a");
+}
+
+TEST_CASE("rpgmaker: MaidsPerfect_v1.0a")
+{
+    test_on("rpgmaker\\MaidsPerfect_v1.0a.rgss3a");
+}
+
+TEST_CASE("rpgmaker: NotSoOrdinaryStory")
+{
+    test_on("rpgmaker\\NotSoOrdinaryStory.rgss3a");
+}
+
+TEST_CASE("rpgmaker: A_Song_of_Elfpai_and_Tentacles_1.20_ENGLISH_")
+{
+    test_on("rpgmaker\\RJ135050_-_A_Song_of_Elfpai_and_Tentacles_1.20_ENGLISH_.rgss3a");
+}
+
+TEST_CASE("rpgmaker: ThroughTheStaticAlpha_v0.1")
+{
+    test_on("rpgmaker\\ThroughTheStaticAlpha_v0.1.rgss3a");
+}
+
+TEST_CASE("rpgmaker: WarlockAndBoobs_v0.350.1.4")
+{
+    test_on("rpgmaker\\WarlockAndBoobs_v0.350.1.4.rgss3a");
+}
+
+TEST_CASE("rpgmaker: WarlockAndBoobs_v0.422.0.1")
+{
+    test_on("rpgmaker\\WarlockAndBoobs_v0.422.0.1.rgss3a");
+}