1 files changed, 450 insertions, 0 deletions

diff --git a/src/common/fs/file.h b/src/common/fs/file.h
new file mode 100644
index 000000000..209f9664b
--- /dev/null
+++ b/src/common/fs/file.h
@@ -0,0 +1,450 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <cstdio>
+#include <filesystem>
+#include <fstream>
+#include <span>
+#include <type_traits>
+#include <vector>
+
+#include "common/concepts.h"
+#include "common/fs/fs_types.h"
+#include "common/fs/fs_util.h"
+
+namespace Common::FS {
+
+enum class SeekOrigin {
+    SetOrigin,       // Seeks from the start of the file.
+    CurrentPosition, // Seeks from the current file pointer position.
+    End,             // Seeks from the end of the file.
+};
+
+/**
+ * Opens a file stream at path with the specified open mode.
+ *
+ * @param file_stream Reference to file stream
+ * @param path Filesystem path
+ * @param open_mode File stream open mode
+ */
+template <typename FileStream>
+void OpenFileStream(FileStream& file_stream, const std::filesystem::path& path,
+                    std::ios_base::openmode open_mode) {
+    file_stream.open(path, open_mode);
+}
+
+#ifdef _WIN32
+template <typename FileStream, typename Path>
+void OpenFileStream(FileStream& file_stream, const Path& path, std::ios_base::openmode open_mode) {
+    if constexpr (IsChar<typename Path::value_type>) {
+        file_stream.open(ToU8String(path), open_mode);
+    } else {
+        file_stream.open(std::filesystem::path{path}, open_mode);
+    }
+}
+#endif
+
+/**
+ * Reads an entire file at path and returns a string of the contents read from the file.
+ * If the filesystem object at path is not a file, this function returns an empty string.
+ *
+ * @param path Filesystem path
+ * @param type File type
+ *
+ * @returns A string of the contents read from the file.
+ */
+[[nodiscard]] std::string ReadStringFromFile(const std::filesystem::path& path, FileType type);
+
+#ifdef _WIN32
+template <typename Path>
+[[nodiscard]] std::string ReadStringFromFile(const Path& path, FileType type) {
+    if constexpr (IsChar<typename Path::value_type>) {
+        return ReadStringFromFile(ToU8String(path), type);
+    } else {
+        return ReadStringFromFile(std::filesystem::path{path}, type);
+    }
+}
+#endif
+
+/**
+ * Writes a string to a file at path and returns the number of characters successfully written.
+ * If an file already exists at path, its contents will be erased.
+ * If the filesystem object at path is not a file, this function returns 0.
+ *
+ * @param path Filesystem path
+ * @param type File type
+ *
+ * @returns Number of characters successfully written.
+ */
+[[nodiscard]] size_t WriteStringToFile(const std::filesystem::path& path, FileType type,
+                                       std::string_view string);
+
+#ifdef _WIN32
+template <typename Path>
+[[nodiscard]] size_t WriteStringToFile(const Path& path, FileType type, std::string_view string) {
+    if constexpr (IsChar<typename Path::value_type>) {
+        return WriteStringToFile(ToU8String(path), type, string);
+    } else {
+        return WriteStringToFile(std::filesystem::path{path}, type, string);
+    }
+}
+#endif
+
+/**
+ * Appends a string to a file at path and returns the number of characters successfully written.
+ * If a file does not exist at path, WriteStringToFile is called instead.
+ * If the filesystem object at path is not a file, this function returns 0.
+ *
+ * @param path Filesystem path
+ * @param type File type
+ *
+ * @returns Number of characters successfully written.
+ */
+[[nodiscard]] size_t AppendStringToFile(const std::filesystem::path& path, FileType type,
+                                        std::string_view string);
+
+#ifdef _WIN32
+template <typename Path>
+[[nodiscard]] size_t AppendStringToFile(const Path& path, FileType type, std::string_view string) {
+    if constexpr (IsChar<typename Path::value_type>) {
+        return AppendStringToFile(ToU8String(path), type, string);
+    } else {
+        return AppendStringToFile(std::filesystem::path{path}, type, string);
+    }
+}
+#endif
+
+class IOFile final : NonCopyable {
+public:
+    IOFile();
+
+    explicit IOFile(const std::string& path, FileAccessMode mode,
+                    FileType type = FileType::BinaryFile,
+                    FileShareFlag flag = FileShareFlag::ShareReadOnly);
+
+    explicit IOFile(std::string_view path, FileAccessMode mode,
+                    FileType type = FileType::BinaryFile,
+                    FileShareFlag flag = FileShareFlag::ShareReadOnly);
+
+    /**
+     * An IOFile is a lightweight wrapper on C Library file operations.
+     * Automatically closes an open file on the destruction of an IOFile object.
+     *
+     * @param path Filesystem path
+     * @param mode File access mode
+     * @param type File type, default is BinaryFile. Use TextFile to open the file as a text file
+     * @param flag (Windows only) File-share access flag, default is ShareReadOnly
+     */
+    explicit IOFile(const std::filesystem::path& path, FileAccessMode mode,
+                    FileType type = FileType::BinaryFile,
+                    FileShareFlag flag = FileShareFlag::ShareReadOnly);
+
+    virtual ~IOFile();
+
+    IOFile(IOFile&& other) noexcept;
+    IOFile& operator=(IOFile&& other) noexcept;
+
+    /**
+     * Gets the path of the file.
+     *
+     * @returns The path of the file.
+     */
+    [[nodiscard]] std::filesystem::path GetPath() const;
+
+    /**
+     * Gets the access mode of the file.
+     *
+     * @returns The access mode of the file.
+     */
+    [[nodiscard]] FileAccessMode GetAccessMode() const;
+
+    /**
+     * Gets the type of the file.
+     *
+     * @returns The type of the file.
+     */
+    [[nodiscard]] FileType GetType() const;
+
+    /**
+     * Opens a file at path with the specified file access mode.
+     * This function behaves differently depending on the FileAccessMode.
+     * These behaviors are documented in each enum value of FileAccessMode.
+     *
+     * @param path Filesystem path
+     * @param mode File access mode
+     * @param type File type, default is BinaryFile. Use TextFile to open the file as a text file
+     * @param flag (Windows only) File-share access flag, default is ShareReadOnly
+     */
+    void Open(const std::filesystem::path& path, FileAccessMode mode,
+              FileType type = FileType::BinaryFile,
+              FileShareFlag flag = FileShareFlag::ShareReadOnly);
+
+#ifdef _WIN32
+    template <typename Path>
+    [[nodiscard]] void Open(const Path& path, FileAccessMode mode,
+                            FileType type = FileType::BinaryFile,
+                            FileShareFlag flag = FileShareFlag::ShareReadOnly) {
+        using ValueType = typename Path::value_type;
+        if constexpr (IsChar<ValueType>) {
+            Open(ToU8String(path), mode, type, flag);
+        } else {
+            Open(std::filesystem::path{path}, mode, type, flag);
+        }
+    }
+#endif
+
+    /// Closes the file if it is opened.
+    void Close();
+
+    /**
+     * Checks whether the file is open.
+     * Use this to check whether the calls to Open() or Close() succeeded.
+     *
+     * @returns True if the file is open, false otherwise.
+     */
+    [[nodiscard]] bool IsOpen() const;
+
+    /**
+     * Helper function which deduces the value type of a contiguous STL container used in ReadSpan.
+     * If T is not a contiguous STL container as defined by the concept IsSTLContainer, this calls
+     * ReadObject and T must be a trivially copyable object.
+     *
+     * See ReadSpan for more details if T is a contiguous container.
+     * See ReadObject for more details if T is a trivially copyable object.
+     *
+     * @tparam T Contiguous container or trivially copyable object
+     *
+     * @param data Container of T::value_type data or reference to object
+     *
+     * @returns Count of T::value_type data or objects successfully read.
+     */
+    template <typename T>
+    [[nodiscard]] size_t Read(T& data) const {
+        if constexpr (IsSTLContainer<T>) {
+            using ContiguousType = typename T::value_type;
+            static_assert(std::is_trivially_copyable_v<ContiguousType>,
+                          "Data type must be trivially copyable.");
+            return ReadSpan<ContiguousType>(data);
+        } else {
+            return ReadObject(data) ? 1 : 0;
+        }
+    }
+
+    /**
+     * Helper function which deduces the value type of a contiguous STL container used in WriteSpan.
+     * If T is not a contiguous STL container as defined by the concept IsSTLContainer, this calls
+     * WriteObject and T must be a trivially copyable object.
+     *
+     * See WriteSpan for more details if T is a contiguous container.
+     * See WriteObject for more details if T is a trivially copyable object.
+     *
+     * @tparam T Contiguous container or trivially copyable object
+     *
+     * @param data Container of T::value_type data or const reference to object
+     *
+     * @returns Count of T::value_type data or objects successfully written.
+     */
+    template <typename T>
+    [[nodiscard]] size_t Write(const T& data) const {
+        if constexpr (IsSTLContainer<T>) {
+            using ContiguousType = typename T::value_type;
+            static_assert(std::is_trivially_copyable_v<ContiguousType>,
+                          "Data type must be trivially copyable.");
+            return WriteSpan<ContiguousType>(data);
+        } else {
+            static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
+            return WriteObject(data) ? 1 : 0;
+        }
+    }
+
+    /**
+     * Reads a span of T data from a file sequentially.
+     * This function reads from the current position of the file pointer and
+     * advances it by the (count of T * sizeof(T)) bytes successfully read.
+     *
+     * Failures occur when:
+     * - The file is not open
+     * - The opened file lacks read permissions
+     * - Attempting to read beyond the end-of-file
+     *
+     * @tparam T Data type
+     *
+     * @param data Span of T data
+     *
+     * @returns Count of T data successfully read.
+     */
+    template <typename T>
+    [[nodiscard]] size_t ReadSpan(std::span<T> data) const {
+        static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
+
+        if (!IsOpen()) {
+            return 0;
+        }
+
+        return std::fread(data.data(), sizeof(T), data.size(), file);
+    }
+
+    /**
+     * Writes a span of T data to a file sequentially.
+     * This function writes from the current position of the file pointer and
+     * advances it by the (count of T * sizeof(T)) bytes successfully written.
+     *
+     * Failures occur when:
+     * - The file is not open
+     * - The opened file lacks write permissions
+     *
+     * @tparam T Data type
+     *
+     * @param data Span of T data
+     *
+     * @returns Count of T data successfully written.
+     */
+    template <typename T>
+    [[nodiscard]] size_t WriteSpan(std::span<const T> data) const {
+        static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
+
+        if (!IsOpen()) {
+            return 0;
+        }
+
+        return std::fwrite(data.data(), sizeof(T), data.size(), file);
+    }
+
+    /**
+     * Reads a T object from a file sequentially.
+     * This function reads from the current position of the file pointer and
+     * advances it by the sizeof(T) bytes successfully read.
+     *
+     * Failures occur when:
+     * - The file is not open
+     * - The opened file lacks read permissions
+     * - Attempting to read beyond the end-of-file
+     *
+     * @tparam T Data type
+     *
+     * @param object Reference to object
+     *
+     * @returns True if the object is successfully read from the file, false otherwise.
+     */
+    template <typename T>
+    [[nodiscard]] bool ReadObject(T& object) const {
+        static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
+        static_assert(!std::is_pointer_v<T>, "T must not be a pointer to an object.");
+
+        if (!IsOpen()) {
+            return false;
+        }
+
+        return std::fread(&object, sizeof(T), 1, file) == 1;
+    }
+
+    /**
+     * Writes a T object to a file sequentially.
+     * This function writes from the current position of the file pointer and
+     * advances it by the sizeof(T) bytes successfully written.
+     *
+     * Failures occur when:
+     * - The file is not open
+     * - The opened file lacks write permissions
+     *
+     * @tparam T Data type
+     *
+     * @param object Const reference to object
+     *
+     * @returns True if the object is successfully written to the file, false otherwise.
+     */
+    template <typename T>
+    [[nodiscard]] bool WriteObject(const T& object) const {
+        static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
+        static_assert(!std::is_pointer_v<T>, "T must not be a pointer to an object.");
+
+        if (!IsOpen()) {
+            return false;
+        }
+
+        return std::fwrite(&object, sizeof(T), 1, file) == 1;
+    }
+
+    /**
+     * Specialized function to read a string of a given length from a file sequentially.
+     * This function writes from the current position of the file pointer and
+     * advances it by the number of characters successfully read.
+     * The size of the returned string may not match length if not all bytes are successfully read.
+     *
+     * @param length Length of the string
+     *
+     * @returns A string read from the file.
+     */
+    [[nodiscard]] std::string ReadString(size_t length) const;
+
+    /**
+     * Specialized function to write a string to a file sequentially.
+     * This function writes from the current position of the file pointer and
+     * advances it by the number of characters successfully written.
+     *
+     * @param string Span of const char backed std::string or std::string_view
+     *
+     * @returns Number of characters successfully written.
+     */
+    [[nodiscard]] size_t WriteString(std::span<const char> string) const;
+
+    /**
+     * Flushes any unwritten buffered data into the file.
+     *
+     * @returns True if the flush was successful, false otherwise.
+     */
+    [[nodiscard]] bool Flush() const;
+
+    /**
+     * Resizes the file to a given size.
+     * If the file is resized to a smaller size, the remainder of the file is discarded.
+     * If the file is resized to a larger size, the new area appears as if zero-filled.
+     *
+     * Failures occur when:
+     * - The file is not open
+     *
+     * @param size File size in bytes
+     *
+     * @returns True if the file resize succeeded, false otherwise.
+     */
+    [[nodiscard]] bool SetSize(u64 size) const;
+
+    /**
+     * Gets the size of the file.
+     *
+     * Failures occur when:
+     * - The file is not open
+     *
+     * @returns The file size in bytes of the file. Returns 0 on failure.
+     */
+    [[nodiscard]] u64 GetSize() const;
+
+    /**
+     * Moves the current position of the file pointer with the specified offset and seek origin.
+     *
+     * @param offset Offset from seek origin
+     * @param origin Seek origin
+     *
+     * @returns True if the file pointer has moved to the specified offset, false otherwise.
+     */
+    [[nodiscard]] bool Seek(s64 offset, SeekOrigin origin = SeekOrigin::SetOrigin) const;
+
+    /**
+     * Gets the current position of the file pointer.
+     *
+     * @returns The current position of the file pointer.
+     */
+    [[nodiscard]] s64 Tell() const;
+
+private:
+    std::filesystem::path file_path;
+    FileAccessMode file_access_mode;
+    FileType file_type;
+
+    std::FILE* file = nullptr;
+};
+
+} // namespace Common::FS