overview

a c-based implementation of a simplified file system. it mimics a windows-style FAT (file allocation table) architecture and supports core file ops like creating, reading, writing, deleting, and managing file descriptors. the project simulates a virtual disk environment for testing too.

implementation

several key components:

• superblock: holds metadata about the file system layout, including directory and FAT sizes, and the starting block of data.
• directory: a statically allocated array that can hold up to 64 files, each entry storing file metadata like name, size, existence flag, reference count, and starting block.
• FAT: an array of 8192 integers representing the file allocation table, where each entry points to the next block in a file or indicates the end of a file.
• file descriptor table: manages open files with entries containing an offset, a usage flag, and an index linking to the directory.
• fs_buffer: a fixed-size buffer (4096 bytes) used for file system operations.

core functions

• make_fs(): initializes the virtual disk, sets up the superblock, FAT, and directory, and writes them to disk.
• mount_fs(): loads the file system from disk into memory, reading the superblock, FAT, and directory.
• umount_fs(): writes the in-memory structures back to disk and closes the virtual disk.
• fs_create(): creates a new file, ensuring the name is valid and not already in use, and allocates a starting block in the FAT.
• fs_open(): opens an existing file by finding an available file descriptor and updating the reference count.
• fs_close(): closes an open file descriptor and decrements the corresponding reference count.
• fs_write() / fs_read(): handles writing to and reading from files, managing offsets and traversing the FAT as needed.
• fs_delete(): removes a file by clearing its directory entry and freeing its blocks in the FAT.

future

definitely room for adding concurrent access controls.