vapfs_ufs/src/structs.rs

use vapfs::{Index, Timestamp};

/// # Magic
/// Constant value that identifies the Superblock as a valid VapUFS filesystem
pub const MAGIC: u64 = 0x766170554653;

/// # Superblock
/// The primary struct of a VapUFS filesystem, contains metadata about the filesystem.
/// Located at byte offset 1024 of the block device.
/// All values are big-endian unless otherwise specified.
/// Directly after the Superblock are the free data blocks bitmap and the free inodes bitmap.
/// Free data blocks bitmap is data_block_count / 8 bytes long (rounded up).
/// Free inodes bitmap is inode_count / 8 bytes long (rounded up).
#[repr(C)]
pub struct Superblock {
    /// magic number that identifies the Superblock as a valid VapUFS filesystem
    pub magic: u64,
    /// size of each block in bytes
    pub block_size: u32,
    /// location of first data block in blocks
    pub first_data_block: Index,
    /// location of first inode block in blocks
    pub first_inode_block: Index,
    /// location of first journal block in blocks
    pub first_journal_block: Index,
    /// total count of inodes, including unused inodes
    pub inode_count: Index,
    /// total count of data blocks, including unused blocks
    pub data_block_count: Index,
    /// total count of blocks dedicated to journal
    pub journal_block_count: Index,
    /// total count of inodes in use
    pub allocated_inode_count: Index,
    /// total count of data blocks in use
    pub allocated_data_block_count: Index,
    /// timestamp of creation
    pub creation_time: Timestamp,
    /// timestamp of last modification
    pub last_modification_time: Timestamp,
    /// reserved values for expansion
    pub reserved: [u64; 8],
    // 156 bytes used so far
    // rest of the block is used by the free data blocks bitmap and the free inodes bitmap
}

/// # UNIXPermissions
/// UNIX permissions
#[repr(u16)]
pub enum UNIXMode {
    /// Read, Other
    Read = 1 << 0,
    /// Write, Other
    Write = 1 << 1,
    /// Execute, Other
    Execute = 1 << 2,
    /// Read, Group
    ReadGroup = 1 << 3,
    /// Write, Group
    WriteGroup = 1 << 4,
    /// Execute, Group
    ExecuteGroup = 1 << 5,
    /// Read, Owner
    ReadOwner = 1 << 6,
    /// Write, Owner
    WriteOwner = 1 << 7,
    /// Execute, Owner
    ExecuteOwner = 1 << 8,
    /// Sticky bit
    Sticky = 1 << 9,
    /// Set GID
    SetGID = 1 << 10,
    /// Set UID
    SetUID = 1 << 11,
}

/// # Filetype
/// Represents a file's type in the last 4 bits of the mode field of an inode.
#[repr(u16)]
pub enum Filetype {
    /// Named FIFO pipe
    FIFO = 0b0001 << 12,
    /// Character device
    CharDevice = 0b0010 << 12,
    /// Directory
    Directory = 0b0011 << 12,
    /// Block device
    BlockDevice = 0b0100 << 12,
    /// Regular file
    RegularFile = 0b0101 << 12,
    /// Symbolic link
    SymbolicLink = 0b0110 << 12,
    /// Socket
    Socket = 0b0111 << 12,
}

/// # Inode
/// Usually represents a file or directory, used to store metadata and locations of data blocks.
#[repr(C)]
pub struct Inode {
    /// UNIX permissions / mode and filetype
    pub mode: u16,
    /// Number of links to this inode
    pub link_count: u16,
    /// User ID of owner
    pub uid: u32,
    /// Group ID of owner
    pub gid: u32,
    /// Size in bytes
    pub size: Index,
    /// Size in blocks
    pub block_count: Index,
    /// Timestamp of creation
    pub creation_time: Timestamp,
    /// Timestamp of last access
    pub last_access_time: Timestamp,
    /// Timestamp of last modification
    pub last_modification_time: Timestamp,
    /// Timestamp of last Inode modification
    pub last_inode_modification_time: Timestamp,
    /// Timestamp of deletion
    pub deletion_time: Timestamp,
    /// Flags field, see `InodeFlags`
    pub flags: u32,
    /// Direct-Block-Addresses, last three are indirect if `InodeFlags::INDIRECT` is set
    /// Indirect blocks are Indexes to other blocks, their contents are a u64 count "N" followed by N u64 indexes
    pub direct_block_addresses: [Index; 12],
    /// CRC32 checksum of this inode
    pub checksum: u32,
}

/// # InodeFlags
/// Flags field of an inode
#[repr(u32)]
pub enum InodeFlags {
    /// File is corrupted
    CORRUPT = 1 << 0,
    /// File uses indirect blocks
    INDIRECT = 1 << 1,
}