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| -rw-r--r-- | dev/kernel/src/FS/NeFS.cc | 4 | ||||
| -rw-r--r-- | docs/tex/nefs.tex | 125 |
2 files changed, 127 insertions, 2 deletions
diff --git a/dev/kernel/src/FS/NeFS.cc b/dev/kernel/src/FS/NeFS.cc index c98841ee..369e1eca 100644 --- a/dev/kernel/src/FS/NeFS.cc +++ b/dev/kernel/src/FS/NeFS.cc @@ -45,9 +45,9 @@ Kernel::SizeT drv_get_size(); /***********************************************************************************/ /// This file implements the New extended File System. -/// New extended File System implements a B-Tree based algortihm. +/// New extended File System implements a flat linked-list based algortihm. /// / -/// /Path1/ /ath2/ +/// /Path1/ /Path2/ /// /readme.rtf /ListContents.pef /readme.lnk <-- symlink. /// /Path1/readme.rtf /***********************************************************************************/ diff --git a/docs/tex/nefs.tex b/docs/tex/nefs.tex new file mode 100644 index 00000000..5b81bb09 --- /dev/null +++ b/docs/tex/nefs.tex @@ -0,0 +1,125 @@ +\documentclass{article} +\usepackage[a4paper,margin=1in]{geometry} +\usepackage{listings} +\usepackage{xcolor} +\usepackage{amsmath} +\usepackage{hyperref} +\usepackage{longtable} +\usepackage{titlesec} +\usepackage{fancyhdr} +\usepackage{caption} +\usepackage{graphicx} + +\definecolor{codegray}{gray}{0.95} +\lstset{ + backgroundcolor=\color{codegray}, + basicstyle=\ttfamily\small, + breaklines=true, + frame=single, + tabsize=4, + language=C++, + showstringspaces=false +} + +\title{NeFS: New Extended File System Specification} +\author{Amlal El Mahrouss} +\date{2025} + +\begin{document} + +\maketitle + +\section{Overview} +NeFS (New Extended File System) is a B-tree-based embedded file system designed to operate over low-level block storage (AHCI/ATA) with a modular architecture. It supports catalogs (like files or directories), forks (similar to macOS data/resource forks), and a formatting mechanism using EPM (Embedded Partition Manager). + +\section{Key Components} + +\subsection*{Mountpoint and Drive Access} +\begin{itemize} + \item `kMountpoint`: Global mountpoint interface to access drives. + \item `DriveTrait`: Interface used to abstract block-level access. +\end{itemize} + +\subsection*{Core Structures} +\begin{longtable}{|l|p{11cm}|} +\hline +\textbf{Structure} & \textbf{Purpose} \\ +\hline +NEFS\_FORK\_STRUCT & Represents a data fork (stream of bytes attached to a catalog). \\ +\hline +NEFS\_CATALOG\_STRUCT & Represents metadata of a file or directory, including fork pointers. \\ +\hline +NEFS\_ROOT\_PARTITION\_BLOCK & Metadata describing a NeFS partition. \\ +\hline +EPM\_PART\_BLOCK & EPM descriptor for bootable partition support. \\ +\hline +\end{longtable} + +\subsection*{Key Functions} + +\begin{itemize} + \item \texttt{CreateCatalog()} — Creates a file or directory catalog. + \item \texttt{CreateFork()} — Adds a fork to a catalog, with LBA linking. + \item \texttt{FindCatalog()} — Finds a catalog by traversing sibling links. + \item \texttt{FindFork()} — Locates a fork by name under a catalog. + \item \texttt{WriteCatalog()} — Writes a fork's data to the correct offset. + \item \texttt{Format()} — Initializes a NeFS + EPM partition on a drive. + \item \texttt{ReadCatalog()} — Reads back a fork's data. + \item \texttt{RemoveCatalog()} — Marks a catalog as deleted and updates partition metadata. +\end{itemize} + +\section{Design Overview} + +\subsection*{Fork Management} +Forks are chained using `NextSibling` pointers and are scanned linearly to find unallocated entries. Forks contain: +\begin{itemize} + \item Fork name + \item Catalog name + \item Flags (e.g., created/deleted) + \item Data size and offset + \item Sibling pointers (Next, Previous) +\end{itemize} + +\subsection*{Catalog Management} +Catalogs act like files or directories. Each has: +\begin{itemize} + \item Name and type (file/dir) + \item Data and resource forks + \item Status flags + \item Chaining via sibling pointers +\end{itemize} +Catalog creation attempts to find a parent first, then finds a free block to allocate the new catalog structure. + +\subsection*{Partition Formatting} +The `Format()` function sets up the NeFS partition and optionally writes an EPM descriptor if bootable. It: +\begin{enumerate} + \item Verifies the drive + \item Initializes partition metadata (sector size, catalog start, etc.) + \item Writes the root directory +\end{enumerate} + +\section{Error Handling} +Errors are written to a global error register using `err\_global\_get()`. Common codes include: +\begin{itemize} + \item \texttt{kErrorDiskIsCorrupted} + \item \texttt{kErrorFileExists} + \item \texttt{kErrorFileNotFound} + \item \texttt{kErrorUnimplemented} +\end{itemize} + +\section{Limitations and Notes} +\begin{itemize} + \item No read/write locking or access concurrency. + \item Assumes in-memory buffers for fork writing. + \item Seek/Tell operations are not implemented — only bulk read/write. + \item Supports one mountpoint at a time. +\end{itemize} + +\section{Future Work} +\begin{itemize} + \item Implement streaming I/O with Seek/Tell. + \item Support multiple mountpoints or drives. + \item Improve metadata journaling and recovery features. +\end{itemize} + +\end{document} |