Initial commit

src/core/inner_fat.h

@@ -0,0 +1,196 @@
+// Copyright 2019 threeSD Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include <type_traits>
+#include <vector>
+#include "common/bit_field.h"
+#include "common/common_funcs.h"
+#include "common/common_types.h"
+#include "common/swap.h"
+
+class SDMCDecryptor;
+
+/// Parameters of the archive, as specified in the Create or Format call.
+struct ArchiveFormatInfo {
+    u32_le total_size;         ///< The pre-defined size of the archive.
+    u32_le number_directories; ///< The pre-defined number of directories in the archive.
+    u32_le number_files;       ///< The pre-defined number of files in the archive.
+    u8 duplicate_data;         ///< Whether the archive should duplicate the data.
+};
+static_assert(std::is_pod<ArchiveFormatInfo>::value, "ArchiveFormatInfo is not POD");
+
+union TableOffset {
+    // This has different meanings for different savegame layouts
+    struct { // duplicate data = true
+        u32_le block_index;
+        u32_le block_count;
+    } duplicate;
+
+    u64_le non_duplicate; // duplicate data = false
+};
+
+struct FATHeader {
+    u32_le magic;
+    u32_le version;
+    u64_le filesystem_information_offset;
+    u64_le image_size;
+    u32_le image_block_size;
+    INSERT_PADDING_BYTES(4);
+};
+static_assert(sizeof(FATHeader) == 0x20, "FATHeader has incorrect size");
+
+struct FileSystemInformation {
+    INSERT_PADDING_BYTES(4);
+    u32_le data_region_block_size;
+    u64_le directory_hash_table_offset;
+    u32_le directory_hash_table_bucket_count;
+    INSERT_PADDING_BYTES(4);
+    u64_le file_hash_table_offset;
+    u32_le file_hash_table_bucket_count;
+    INSERT_PADDING_BYTES(4);
+    u64_le file_allocation_table_offset;
+    u32_le file_allocation_table_entry_count;
+    INSERT_PADDING_BYTES(4);
+    u64_le data_region_offset;
+    u32_le data_region_block_count;
+    INSERT_PADDING_BYTES(4);
+    TableOffset directory_entry_table;
+    u32_le maximum_directory_count;
+    INSERT_PADDING_BYTES(4);
+    TableOffset file_entry_table;
+    u32_le maximum_file_count;
+    INSERT_PADDING_BYTES(4);
+};
+static_assert(sizeof(FileSystemInformation) == 0x68, "FileSystemInformation has incorrect size");
+
+struct DirectoryEntryTableEntry {
+    u32_le parent_directory_index;
+    std::array<char, 16> name;
+    u32_le next_sibling_index;
+    u32_le first_subdirectory_index;
+    u32_le first_file_index;
+    INSERT_PADDING_BYTES(4);
+    u32_le next_hash_bucket_entry;
+};
+static_assert(sizeof(DirectoryEntryTableEntry) == 0x28,
+              "DirectoryEntryTableEntry has incorrect size");
+
+struct FileEntryTableEntry {
+    u32_le parent_directory_index;
+    std::array<char, 16> name;
+    u32_le next_sibling_index;
+    INSERT_PADDING_BYTES(4);
+    u32_le data_block_index;
+    u64_le file_size;
+    INSERT_PADDING_BYTES(4);
+    u32_le next_hash_bucket_entry;
+};
+static_assert(sizeof(FileEntryTableEntry) == 0x30, "FileEntryTableEntry has incorrect size");
+
+struct FATNode {
+    union {
+        BitField<0, 31, u32> index;
+        BitField<31, 1, u32> flag;
+
+        u32_le raw;
+    } u, v;
+};
+
+/**
+ * Virtual interface for the inner FAT filesystem of SD Savegames/Extdata/TitleDB.
+ */
+class InnerFAT {
+public:
+    virtual ~InnerFAT();
+
+    /**
+     * Returns whether the filesystem is in "good" state, i.e. successfully initialized.
+     */
+    bool IsGood() const;
+
+    /**
+     * Completely extracts everything from this filesystem, including files, directories
+     * and metadata used by Citra.
+     * @return true on success, false otherwise
+     */
+    virtual bool Extract(std::string path) const = 0;
+
+protected:
+    /**
+     * Gets the ArchiveFormatInfo of this archive, used for writing the archive metadata.
+     */
+    virtual ArchiveFormatInfo GetFormatInfo() const = 0;
+
+    /**
+     * Extracts the index-th file in the file entry table to a certain path. (The path does not
+     * contain the file name).
+     * @return true on success, false otherwise
+     */
+    virtual bool ExtractFile(const std::string& path, std::size_t index) const = 0;
+
+    /**
+     * Recursively extracts the index-th directory in the directory entry table.
+     * @return true on success, false otherwise
+     */
+    bool ExtractDirectory(const std::string& path, std::size_t index) const;
+
+    /**
+     * Writes the corresponding archive metadata to a certain path.
+     * @return true on success, false otherwise
+     */
+    bool WriteMetadata(const std::string& path) const;
+
+    bool is_good = false;
+    FATHeader header;
+    FileSystemInformation fs_info;
+    std::vector<DirectoryEntryTableEntry> directory_entry_table;
+    std::vector<FileEntryTableEntry> file_entry_table;
+    std::vector<u8> data_region;
+};
+
+class SDSavegame : public InnerFAT {
+public:
+    explicit SDSavegame(std::vector<u8> data);
+    explicit SDSavegame(std::vector<u8> partitionA, std::vector<u8> partitionB);
+    ~SDSavegame() override;
+
+    bool Extract(std::string path) const override;
+
+private:
+    bool Init();
+    bool ExtractFile(const std::string& path, std::size_t index) const override;
+    ArchiveFormatInfo GetFormatInfo() const override;
+
+    std::vector<FATNode> fat;
+    bool duplicate_data; // Layout variant
+
+    // Temporary storage for construction data
+    std::vector<u8> data;
+    std::vector<u8> partitionA;
+    std::vector<u8> partitionB;
+};
+
+class SDExtdata : public InnerFAT {
+public:
+    /**
+     * Loads an SD extdata folder.
+     * @param data_path Path to the ENCRYPTED SD extdata folder, relative to decryptor root
+     * @param decryptor Const reference to the SDMCDecryptor.
+     */
+    explicit SDExtdata(std::string data_path, const SDMCDecryptor& decryptor);
+    ~SDExtdata() override;
+
+    bool Extract(std::string path) const override;
+
+private:
+    bool Init();
+    bool ExtractFile(const std::string& path, std::size_t index) const override;
+    ArchiveFormatInfo GetFormatInfo() const override;
+
+    std::string data_path;
+    const SDMCDecryptor& decryptor;
+};