stpdfs.inc

Summary

stpdfs.inc
Stupid Filesystem
Constants and Enumerations
STPDFS_SB_MAGIC	Superblock magic number, MUST BE `0x44505453` (STPD)
STPDFS_SB_REV	StupidFS revision, currently `0x1`
STPDFS_BSIZE	StupidFS block size (512)
STPDFS_BADINO	StupidFS bad inode
STPDFS_ROOTINO	StupidFS root inode number
STPDFS_NDIRECT	Number of direct block (7)
STPDFS_INDIRECT_PER_BLOCK
STPDFS_NAME_MAX	Max file name length (28)
StupidFS State
StupidFS i-node flags
STPDFS_INODE_PER_BLOCK	I-node per block
STPDFS_DIRENT_PER_BLOCK	Directory entry per block
Structs
StpdFS_FreeList
StpdFS_Sb
StpdFS_Inode	StupidFS on disk i-node
StpdFS_Dirent	StupidFS directory entry
Implementation

Stupid Filesystem

┌──────────┬───────────┬──────┬───┬──────┬────┬───┬────┐
│Boot block│Super block│Inodes│...│Inodes│Data│...│Data│
└──────────┴───────────┴──────┴───┴──────┴────┴───┴────┘

Summary

Constants and Enumerations
STPDFS_SB_MAGIC	Superblock magic number, MUST BE `0x44505453` (STPD)
STPDFS_SB_REV	StupidFS revision, currently `0x1`
STPDFS_BSIZE	StupidFS block size (512)
STPDFS_BADINO	StupidFS bad inode
STPDFS_ROOTINO	StupidFS root inode number
STPDFS_NDIRECT	Number of direct block (7)
STPDFS_INDIRECT_PER_BLOCK
STPDFS_NAME_MAX	Max file name length (28)
StupidFS State
StupidFS i-node flags
STPDFS_INODE_PER_BLOCK	I-node per block
STPDFS_DIRENT_PER_BLOCK	Directory entry per block
Structs
StpdFS_FreeList
StpdFS_Sb
StpdFS_Inode	StupidFS on disk i-node
StpdFS_Dirent	StupidFS directory entry

Constants and Enumerations

STPDFS_SB_MAGIC

STPDFS_SB_MAGIC = 0x44505453

Superblock magic number, MUST BE `0x44505453` (STPD)

STPDFS_SB_REV

STPDFS_SB_REV = 1

StupidFS revision, currently `0x1`

STPDFS_BSIZE

STPDFS_BSIZE = 512

StupidFS block size (512)

STPDFS_BADINO

STPDFS_BADINO = 0

StupidFS bad inode

STPDFS_ROOTINO

STPDFS_ROOTINO = 1

StupidFS root inode number

STPDFS_NDIRECT

STPDFS_NDIRECT = 7

Number of direct block (7)

STPDFS_INDIRECT_PER_BLOCK

STPDFS_INDIRECT_PER_BLOCK = STPDFS_BSIZE / 4

STPDFS_NAME_MAX

STPDFS_NAME_MAX = 28

Max file name length (28)

StupidFS State

STPDFS_CLEANLY_UNMOUNTED	0
STPDFS_ERROR	1
STPDFS_DIRTY	1

StupidFS i-node flags

STPDFS_INO_FLAG_ALOC	I-node is allocated
STPDFS_INO_FLAG_LZP	I-node data is compressed using LZP algorithm (see lzp.asm)
STPDFS_INO_FLAG_ENC	I-node data is encrypted with XChaCha12 (see xchacha.asm)

STPDFS_INODE_PER_BLOCK

STPDFS_INODE_PER_BLOCK = sizeof.StpdFS_Inode / STPDFS_BSIZE

I-node per block

STPDFS_DIRENT_PER_BLOCK

STPDFS_DIRENT_PER_BLOCK = sizeof.StpdFS_Dirent / STPDFS_BSIZE

Directory entry per block

Structs

StpdFS_FreeList

struc StpdFS_FreeList

.free	List of free block (0-99), index 0 point to next freelist
.nfree	Index

┌──────────┐
│ block 99 │
├──────────┤
│ block 98 │
├──────────┤
│ ...      │
├──────────┤
│ block 2  │
├──────────┤
│ block 1  │
├──────────┤    ┌──────────┐
│ block 0  ├───►│ block 99 │
└──────────┘    ├──────────┤
                │ ...      │
                ├──────────┤    ┌──────────┐
                │ block 0  ├───►│ block 99 │
                └──────────┘    ├──────────┤
                                │ ...      │
                                ├──────────┤
                                │ block 0  │
                                └──────────┘

StpdFS_Sb

struc StpdFS_Sb

.magic	See STPDFS_SB_MAGIC
.isize	Size in block of the i-node list
.fsize	Size in block of the entire volume
.freelist	See StpdFS_FreeList
.rev	See STPDFS_SB_REV
.state	See StupidFS State
.time	Last mod time (64bit UNIX timestamp)

StpdFS_Inode

struc StpdFS_Inode

StupidFS on disk i-node

.mode	File mode
.nlink	Links count
.uid	Owner Uid
.gid	Group Id
.flags	File flags, see StupidFS i-node flags
.size	Data size in byte
.zone	See bellow
.actime	Access time (64-bit UNIX timestamp)
.modtime	Modification time (64-bit UNIX timestamp)

Zone 0-6 are direct, zone 7 indirect, zone 8 double indirect, zone 9 triple indirect

                        ┌────────┐
                        │        │
               ┌───────►│Data    │
               │        │        │
┌──────┐ Direct│        └────────┘
│zone 0├───────┘
├──────┤
│...   │
├──────┤          ┌────────┐      ┌────────┐
│zone 6│          │        ├─────►│        │
├──────┤ Indirect │        │      │ Data   │
│zone 7├─────────►│        │      │        │
├──────┤          └────────┘      └────────┘
│zone 8├───────┐
├──────┤       │Double indirect┌────────┐    ┌────────┐    ┌────────┐
│zone 9│       └──────────────►│        ├───►│        ├───►│        │
└──┬───┘                       │        │    │        │    │ Data   │
   │                           │        │    │        │    │        │
   │                           └────────┘    └────────┘    └────────┘
   │ Triple indirect ┌────────┐
   └────────────────►│        │    ┌────────┐      ┌────────┐      ┌────────┐
                     │        ├───►│        │      │        │      │        │
                     │        │    │        ├─────►│        ├─────►│ Data   │
                     └────────┘    │        │      │        │      │        │
                                   └────────┘      └────────┘      └────────┘

StpdFS_Dirent

struc StpdFS_Dirent

StupidFS directory entry

.inode	address of i-node
.name	null terminated file name (see STPDFS_NAME_MAX)