filesystem_bsfs.h File Reference

Core data structures for the BSFS (Basic Solution File System). More...

Classes
struct	superblock_t
	Represents the superblock of the BSFS file system. More...
struct	bitmap_block_t
	Represents a block of the allocation bitmap in the BSFS file system. More...
struct	bspan_t
	Represents a contiguous span of blocks in the BSFS file system. More...
struct	inode_t
	Represents an inode in the BSFS file system. More...
struct	rec_entry_t
	Represents a deleted file entry stored in the recovery B-tree. More...
struct	dir_entry_t
	Represents a directory entry in the BSFS file system. More...
struct	file_t
	Represents an open file in memory within the BSFS file system. More...

Macros
#define	MAGIC_NUMBER   0x53465342
	Magic number used to identify a BSFS-formatted file system.
#define	BLOCK_SIZE   4096
	Size of a block in bytes.
#define	MAX_FILENAME   255
	Maximum length (in bytes) of a file or directory name.
#define	INODE_SIZE   512
	Size of an inode in bytes.
#define	ADDRESSES_PER_BLOCK   (BLOCK_SIZE / sizeof(uint32_t))
	Number of 32-bit addresses that fit in a block.
#define	BITMAP_BLOCK_BYTES   (BLOCK_SIZE - sizeof(uint32_t))
	Number of usable bytes for bitmap bits in a bitmap block.
#define	INVALID_BLOCK   0xFFFFFFFF
	Special value representing an invalid or null block reference.
#define	FILE_TYPE_DIR   1
#define	FILE_TYPE_FILE   2
#define	DEFAULT_RECOVERY_TTL   (30ULL * 24ULL * 60ULL * 60ULL)

Detailed Description

Core data structures for the BSFS (Basic Solution File System).

This header file defines the main data structures used by the BSFS file system, both on-disk and in-memory. It includes:

• superblock_t: The superblock structure containing metadata about the file system layout, such as block size, number of blocks, bitmap location, inode roots, and root inode.
• bitmap_block_t: A structure used to represent a bitmap block, including a pointer to the next bitmap block for chaining.
• bspan_t: Describes a logical-to-physical mapping of file blocks (block spans), representing contiguous ranges of allocated disk blocks.
• inode_t: Metadata structure for files and directories, including size, permissions, timestamps, block mappings, and root pointers to B-trees.
• rec_entry_t: A simple structure representing entries in the recovery system.
• dir_entry_t: Represents a directory entry, mapping filenames to inode numbers.
• file_t: In-memory representation of an open file, tracking seek position and inode data.
• dir_t: In-memory representation of an open directory, tracking iteration index and inode data.

These structures define the foundation of the BSFS layout and behavior, and are used throughout the system for file management, block allocation, recovery, and directory operations.

Macro Definition Documentation

ADDRESSES_PER_BLOCK

#define ADDRESSES_PER_BLOCK   (BLOCK_SIZE / sizeof(uint32_t))

Number of 32-bit addresses that fit in a block.

Used for indexing and pointer arrays inside blocks. Helper: number of 32-bit addresses per block.

BITMAP_BLOCK_BYTES

#define BITMAP_BLOCK_BYTES   (BLOCK_SIZE - sizeof(uint32_t))

Number of usable bytes for bitmap bits in a bitmap block.

The last 4 bytes of the block are reserved for the next block pointer. Usable bytes in a bitmap block (reserve 4B for next pointer).

BLOCK_SIZE

#define BLOCK_SIZE   4096

Size of a block in bytes.

All operations in the file system are based on fixed-size blocks. Logical block size in bytes.

DEFAULT_RECOVERY_TTL

#define DEFAULT_RECOVERY_TTL   (30ULL * 24ULL * 60ULL * 60ULL)

Default retention period for recovery entries (seconds).

FILE_TYPE_DIR

#define FILE_TYPE_DIR   1

File type code: directory.

FILE_TYPE_FILE

#define FILE_TYPE_FILE   2

File type code: regular file.

INODE_SIZE

#define INODE_SIZE   512

Size of an inode in bytes.

Used when allocating or reading inodes from disk. Size of an inode on disk (bytes).

INVALID_BLOCK

#define INVALID_BLOCK   0xFFFFFFFF

Special value representing an invalid or null block reference.

Sentinel for an invalid or absent block address.

MAGIC_NUMBER

#define MAGIC_NUMBER   0x53465342

Magic number used to identify a BSFS-formatted file system.

Represents the ASCII string "BSFS" encoded as hexadecimal. Magic number used to identify a BSFS image ("BSFS" in hex).

MAX_FILENAME

#define MAX_FILENAME   255

Maximum length (in bytes) of a file or directory name.

Does not include the null terminator. Maximum filename length (bytes, excluding NUL).