Introduce basic RomFS support

This commit adds support for reading the RomFS data from an NRO and
obtaining an IStorage handle to it through 'OpenDataStorageByCurrentProcess'.
There is currently only support for reading and no support
for enlarging or writing.

Also fixup a few capitalisation issues.

app/src/main/cpp/skyline/loader/loader.h

@@ -26,6 +26,7 @@ namespace skyline::loader {
 
       public:
         std::shared_ptr<vfs::NACP> nacp; //!< The NACP of the current application
+        std::shared_ptr<vfs::Backing> romFs; //!< The RomFS of the current application
 
         /**
          * @param backing The backing for the NRO

app/src/main/cpp/skyline/loader/nro.cpp

@@ -24,6 +24,9 @@ namespace skyline::loader {
 
             NroAssetSection &nacpHeader = assetHeader.nacp;
             nacp = std::make_shared<vfs::NACP>(std::make_shared<vfs::RegionBacking>(backing, header.size + nacpHeader.offset, nacpHeader.size));
+
+            NroAssetSection &romFsHeader = assetHeader.romFs;
+            romFs = std::make_shared<vfs::RegionBacking>(backing, header.size + romFsHeader.offset, romFsHeader.size);
         }
     }
 

app/src/main/cpp/skyline/loader/nro.h

@@ -60,8 +60,8 @@ namespace skyline::loader {
             u32 magic; //!< The asset section magic "ASET"
             u32 version; //!< The format version
             NroAssetSection icon; //!< The header describing the location of the icon
-            NroAssetSection nacp; //!< The header describing the location of the nacp
+            NroAssetSection nacp; //!< The header describing the location of the NACP
-            NroAssetSection romfs; //!< The header describing the location of the romfs
+            NroAssetSection romFs; //!< The header describing the location of the RomFS
         } assetHeader{};
 
         /**

app/src/main/cpp/skyline/services/base_service.h

@@ -52,6 +52,7 @@ namespace skyline::service {
         timesrv_ITimeZoneService,
         fssrv_IFileSystemProxy,
         fssrv_IFileSystem,
+        fssrv_IStorage,
         nvdrv_INvDrvServices,
         visrv_IManagerRootService,
         visrv_IApplicationDisplayService,

app/src/main/cpp/skyline/services/fssrv/IFileSystemProxy.cpp

@@ -1,12 +1,15 @@
 // SPDX-License-Identifier: MPL-2.0
 // Copyright © 2020 Skyline Team and Contributors (https://github.com/skyline-emu/)
 
+#include <loader/loader.h>
 #include "IFileSystemProxy.h"
+#include "IStorage.h"
 
 namespace skyline::service::fssrv {
     IFileSystemProxy::IFileSystemProxy(const DeviceState &state, ServiceManager &manager) : BaseService(state, manager, Service::fssrv_IFileSystemProxy, "fssrv:IFileSystemProxy", {
         {0x1, SFUNC(IFileSystemProxy::SetCurrentProcess)},
-        {0x12, SFUNC(IFileSystemProxy::OpenSdCardFileSystem)}
+        {0x12, SFUNC(IFileSystemProxy::OpenSdCardFileSystem)},
+        {0xc8, SFUNC(IFileSystemProxy::OpenDataStorageByCurrentProcess)}
     }) {}
 
     void IFileSystemProxy::SetCurrentProcess(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response) {
@@ -16,4 +19,11 @@ namespace skyline::service::fssrv {
     void IFileSystemProxy::OpenSdCardFileSystem(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response) {
         manager.RegisterService(std::make_shared<IFileSystem>(FsType::SdCard, state, manager), session, response);
     }
+
+    void IFileSystemProxy::OpenDataStorageByCurrentProcess(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response) {
+        if (state.loader->romFs)
+            manager.RegisterService(std::make_shared<IStorage>(state.loader->romFs, state, manager), session, response);
+        else
+            throw exception("Tried to call OpenDataStorageByCurrentProcess without a valid RomFS");
+    }
 }

app/src/main/cpp/skyline/services/fssrv/IFileSystemProxy.h

@@ -26,5 +26,10 @@ namespace skyline::service::fssrv {
          * @brief This returns a handle to an instance of #IFileSystem (https://switchbrew.org/wiki/Filesystem_services#IFileSystem) with type SDCard
          */
         void OpenSdCardFileSystem(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response);
+
+        /**
+         * @brief This returns a handle to an instance of #IStorage (https://switchbrew.org/wiki/Filesystem_services#IStorage) for the application's data storage
+         */
+        void OpenDataStorageByCurrentProcess(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response);
     };
 }

app/src/main/cpp/skyline/services/fssrv/IStorage.cpp

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: MPL-2.0
+// Copyright © 2020 Skyline Team and Contributors (https://github.com/skyline-emu/)
+
+#include <kernel/types/KProcess.h>
+#include "IStorage.h"
+
+namespace skyline::service::fssrv {
+    IStorage::IStorage(std::shared_ptr<vfs::Backing> &backing, const DeviceState &state, ServiceManager &manager) : backing(backing), BaseService(state, manager, Service::fssrv_IStorage, "fssrv:IStorage", {
+        {0x0, SFUNC(IStorage::Read)},
+        {0x4, SFUNC(IStorage::GetSize)}
+    }) {}
+
+    void IStorage::Read(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response) {
+        auto offset = request.Pop<u64>();
+        auto size = request.Pop<u64>();
+
+        backing->Read(state.process->GetPointer<u8>(request.outputBuf.at(0).address), offset, size);
+    }
+
+    void IStorage::GetSize(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response) {
+        response.Push<u64>(backing->size);
+    }
+}

app/src/main/cpp/skyline/services/fssrv/IStorage.h

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MPL-2.0
+// Copyright © 2020 Skyline Team and Contributors (https://github.com/skyline-emu/)
+
+#pragma once
+
+#include <services/base_service.h>
+#include <services/serviceman.h>
+#include <vfs/backing.h>
+
+namespace skyline::service::fssrv {
+    /**
+     * @brief IStorage is an interface to a raw backing device (https://switchbrew.org/wiki/Filesystem_services#IStorage)
+     */
+    class IStorage : public BaseService {
+      private:
+        std::shared_ptr<vfs::Backing> backing; //!< The backing of the IStorage
+
+      public:
+        IStorage(std::shared_ptr<vfs::Backing> &backing, const DeviceState &state, ServiceManager &manager);
+
+        /**
+         * @brief This reads a buffer from a region of an IStorage (https://switchbrew.org/wiki/Filesystem_services#Read)
+         */
+        void Read(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response);
+
+        /**
+         * @brief This obtains the size of an IStorage (https://switchbrew.org/wiki/Filesystem_services#GetSize)
+         */
+        void GetSize(type::KSession &session, ipc::IpcRequest &request, ipc::IpcResponse &response);
+    };
+}