Archives: Implemented ExtSaveData and SharedExtSaveData

They will be stored in /extsavedata/SDMC and /extsavedata/NAND respectively.
Also redirect some APT_A functions to their APT_U equivalents.
Implemented the gamecoin.dat file in SharedExtSaveData in the PTM module.
Implemented formatting the savegame.
Retake a previous savegame if it exists instead of reporting them as not formatted every time a game is loaded.

src/core/file_sys/archive_backend.h

@@ -46,6 +46,9 @@ public:
     Path(const char* path) : type(Char), string(path) {
     }
 
+    Path(std::vector<u8> binary_data) : type(Binary), binary(std::move(binary_data)) {
+    }
+
     Path(LowPathType type, u32 size, u32 pointer) : type(type) {
         switch (type) {
         case Binary:
@@ -174,6 +177,20 @@ public:
     virtual ~ArchiveBackend() {
     }
 
+    /**
+     * Tries to open the archive of this type with the specified path
+     * @param path Path to the archive
+     * @return ResultCode of the operation
+     */
+    virtual ResultCode Open(const Path& path) = 0;
+
+    /**
+     * Deletes the archive contents and then re-creates the base folder
+     * @param path Path to the archive
+     * @return ResultCode of the operation, 0 on success
+     */
+    virtual ResultCode Format(const Path& path) const = 0;
+
     /**
      * Get a descriptive name for the archive (e.g. "RomFS", "SaveData", etc.)
      */

src/core/file_sys/archive_extsavedata.cpp

@@ -0,0 +1,59 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <sys/stat.h>
+
+#include "common/common_types.h"
+#include "common/file_util.h"
+
+#include "core/file_sys/archive_extsavedata.h"
+#include "core/file_sys/disk_archive.h"
+#include "core/settings.h"
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// FileSys namespace
+
+namespace FileSys {
+
+static std::string GetExtSaveDataPath(const std::string& mount_point, const Path& path) {
+    std::vector<u8> vec_data = path.AsBinary();
+    const u32* data = reinterpret_cast<const u32*>(vec_data.data());
+    u32 media_type = data[0];
+    u32 save_low = data[1];
+    u32 save_high = data[2];
+    return Common::StringFromFormat("%s%s/%08X/%08X/", mount_point.c_str(), media_type == 0 ? "nand" : "sdmc", save_high, save_low);
+}
+
+Archive_ExtSaveData::Archive_ExtSaveData(const std::string& mount_point)
+        : DiskArchive(mount_point), concrete_mount_point(mount_point) {
+    LOG_INFO(Service_FS, "Directory %s set as base for ExtSaveData.", this->mount_point.c_str());
+}
+
+bool Archive_ExtSaveData::Initialize() {
+    if (!FileUtil::CreateFullPath(mount_point)) {
+        LOG_ERROR(Service_FS, "Unable to create ExtSaveData base path.");
+        return false;
+    }
+
+    return true;
+}
+
+ResultCode Archive_ExtSaveData::Open(const Path& path) {
+    std::string fullpath = GetExtSaveDataPath(mount_point, path);
+    if (!FileUtil::Exists(fullpath)) {
+        // TODO(Subv): Check error code, this one is probably wrong
+        return ResultCode(ErrorDescription::FS_NotFormatted, ErrorModule::FS,
+            ErrorSummary::InvalidState, ErrorLevel::Status);
+    }
+    concrete_mount_point = fullpath;
+    return RESULT_SUCCESS;
+}
+
+ResultCode Archive_ExtSaveData::Format(const Path& path) const {
+    std::string fullpath = GetExtSaveDataPath(mount_point, path);
+    FileUtil::CreateFullPath(fullpath);
+    return RESULT_SUCCESS;
+}
+
+} // namespace FileSys

src/core/file_sys/archive_extsavedata.h

@@ -0,0 +1,45 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+
+#include "core/file_sys/disk_archive.h"
+#include "core/loader/loader.h"
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// FileSys namespace
+
+namespace FileSys {
+
+/// File system interface to the ExtSaveData archive
+class Archive_ExtSaveData final : public DiskArchive {
+public:
+    Archive_ExtSaveData(const std::string& mount_point);
+
+    /**
+     * Initialize the archive.
+     * @return true if it initialized successfully
+     */
+    bool Initialize();
+
+    ResultCode Open(const Path& path) override;
+    ResultCode Format(const Path& path) const override;
+    std::string GetName() const override { return "ExtSaveData"; }
+
+    const std::string& GetMountPoint() const override {
+        return concrete_mount_point;
+    }
+
+protected:
+    /**
+     * This holds the full directory path for this archive, it is only set after a successful call to Open, 
+     * this is formed as <base extsavedatapath>/<type>/<high>/<low>. 
+     * See GetExtSaveDataPath for the code that extracts this data from an archive path.
+     */
+    std::string concrete_mount_point;
+};
+
+} // namespace FileSys

src/core/file_sys/archive_romfs.cpp

@@ -62,4 +62,9 @@ std::unique_ptr<DirectoryBackend> Archive_RomFS::OpenDirectory(const Path& path)
     return Common::make_unique<Directory_RomFS>();
 }
 
+ResultCode Archive_RomFS::Format(const Path& path) const {
+    LOG_WARNING(Service_FS, "Attempted to format ROMFS.");
+    return UnimplementedFunction(ErrorModule::FS);
+}
+
 } // namespace FileSys

src/core/file_sys/archive_romfs.h

@@ -83,6 +83,12 @@ public:
      */
     std::unique_ptr<DirectoryBackend> OpenDirectory(const Path& path) const override;
 
+    ResultCode Open(const Path& path) override {
+        return RESULT_SUCCESS;
+    }
+
+    ResultCode Format(const Path& path) const override;
+
 private:
     friend class File_RomFS;
 

src/core/file_sys/archive_savedata.cpp

@@ -16,18 +16,29 @@
 
 namespace FileSys {
 
-Archive_SaveData::Archive_SaveData(const std::string& mount_point, u64 program_id)
-        : DiskArchive(mount_point + Common::StringFromFormat("%016X", program_id) + DIR_SEP) {
+Archive_SaveData::Archive_SaveData(const std::string& mount_point)
+        : DiskArchive(mount_point) {
     LOG_INFO(Service_FS, "Directory %s set as SaveData.", this->mount_point.c_str());
 }
 
-bool Archive_SaveData::Initialize() {
-    if (!FileUtil::CreateFullPath(mount_point)) {
-        LOG_ERROR(Service_FS, "Unable to create SaveData path.");
-        return false;
+ResultCode Archive_SaveData::Open(const Path& path) {
+    if (concrete_mount_point.empty())
+        concrete_mount_point = Common::StringFromFormat("%s%016X", mount_point.c_str(), Kernel::g_program_id) + DIR_SEP;
+    if (!FileUtil::Exists(concrete_mount_point)) {
+        // When a SaveData archive is created for the first time, it is not yet formatted
+        // and the save file/directory structure expected by the game has not yet been initialized. 
+        // Returning the NotFormatted error code will signal the game to provision the SaveData archive 
+        // with the files and folders that it expects. 
+        return ResultCode(ErrorDescription::FS_NotFormatted, ErrorModule::FS,
+            ErrorSummary::InvalidState, ErrorLevel::Status);
     }
+    return RESULT_SUCCESS;
+}
 
-    return true;
+ResultCode Archive_SaveData::Format(const Path& path) const {
+    FileUtil::DeleteDirRecursively(concrete_mount_point);
+    FileUtil::CreateFullPath(concrete_mount_point);
+    return RESULT_SUCCESS;
 }
 
 } // namespace FileSys

src/core/file_sys/archive_savedata.h

@@ -17,15 +17,20 @@ namespace FileSys {
 /// File system interface to the SaveData archive
 class Archive_SaveData final : public DiskArchive {
 public:
-    Archive_SaveData(const std::string& mount_point, u64 program_id);
-
-    /**
-     * Initialize the archive.
-     * @return true if it initialized successfully
-     */
-    bool Initialize();
+    Archive_SaveData(const std::string& mount_point);
 
     std::string GetName() const override { return "SaveData"; }
+
+    ResultCode Open(const Path& path) override;
+
+    ResultCode Format(const Path& path) const override;
+
+    const std::string& GetMountPoint() const override {
+        return concrete_mount_point;
+    }
+
+protected:
+    std::string concrete_mount_point;
 };
 
 } // namespace FileSys

src/core/file_sys/disk_archive.h

@@ -25,6 +25,7 @@ public:
     DiskArchive(const std::string& mount_point_) : mount_point(mount_point_) {}
 
     virtual std::string GetName() const = 0;
+    virtual ResultCode Format(const Path& path) const { return RESULT_SUCCESS; }
     std::unique_ptr<FileBackend> OpenFile(const Path& path, const Mode mode) const override;
     bool DeleteFile(const Path& path) const override;
     bool RenameFile(const Path& src_path, const Path& dest_path) const override;
@@ -34,11 +35,15 @@ public:
     bool RenameDirectory(const Path& src_path, const Path& dest_path) const override;
     std::unique_ptr<DirectoryBackend> OpenDirectory(const Path& path) const override;
 
+    virtual ResultCode Open(const Path& path) override {
+        return RESULT_SUCCESS;
+    }
+
     /**
      * Getter for the path used for this Archive
      * @return Mount point of that passthrough archive
      */
-    const std::string& GetMountPoint() const {
+    virtual const std::string& GetMountPoint() const {
         return mount_point;
     }