List File System is based on doubly linked lists. LIFS supports partitioning and each partition is a node of the list. LIFS contains files (LIFS units), directory is a file that doesn't have data but data pointer points to first file in this directory.
NOTICE! First partition sector must be within first 255 disk sectors, lower byte of its sector id is stored in 4th byte of MBR.
Sector ids: global sector id - id of sector on disk, local - on current partition.
Each partition has its own header. The header contains following fields (each field is 32 bits):
| Field | Description |
|---|---|
| Signature | LIFS signature is always 0x5346494C ("LIFS") |
| Version | LIFS version. Actual is 1.0 |
| BS data | Reserved for boot system data |
| Label | LIFS has 3 types of labels: BOOT, ROOT, DATA |
| Sector | Global id of this header disk sector |
| Size | LIFS size in sectors (sector is 512 bytes) |
| Flags | Partition flags, see flags |
| Content | Local id of sector with first file on this partition |
| Bitmap start | Local id of first sector with bitmap |
| Bitmap size | Size of bitmap in sectors |
| UID higher | UID higher 32 bits |
| UID lower | UID lower 32 bits |
| System | Reserved for OS data |
| Mount | Global id of sector with this partition mount directory |
| Previous | Global id of sector with previous partition header (if 0 - first) |
| Next | Global id of sector with next partition header (if 0 - last) |
| Reserved x 448 | Reserved for aligning to sector size |
| Flag | Description |
|---|---|
| boot | Whether this is boot partition |
| root | Whether this is root partition |
| data | Whether this is data partition |
| protected | Whether this partition is protected from writing |
| mounted | Whether this partition is mounted |
| reserved | Reserved for aligning to 32 bits |
Bitmap is located after partition header and shows which sectors are used and which are free. Each bit of this bitmap is a flag that shows sector state (1 - used, 0 - free).
LIFS units are files and directories. Each unit has header and content sectors (for file - file data, for directory - files). All units form hierarchical lists: directories and files located on same level form list, directories and files located 1 level below or above forms their own lists.
| Field | Description |
|---|---|
| Name | 256 chars name of this unit in UTF-8 |
| Link | Real unit that linked here (Global id of header sector) |
| Size | Unit size (file - size sectors, directory - files count) |
| Flags | Unit flags |
| Content | Local id of sector with content (see this) |
| Sector | Local id of this header sector |
| Parent | Local id of this unit parent (if 0 - in root of LIFS) |
| Previous | Local id of sector with previous unit header (if 0 - first) |
| Next | Local id of sector with next unit header (if 0 - last) |
| Additional | Reserved for additional data or system-specified data |
| Created | Time when this unit was created (in seconds since 01.01.2020) |
| Edited | Time when this unit was last edited (in seconds since 01.01.2020) |
| Accessed | Time when this unit was last accessed (in seconds since 01.01.2020) |
| Reserved | Reserved for aligning to 512 bytes |
| Flag | Description |
|---|---|
| dir | Whether this unit is a directory |
| link | Whether this unit is a link entry of other unit |
| os | Whether this file is a part of OS |
| dev | Whether this file is a device entry |
| encrypted | Whether this file is encrypted |
| accessed | Whether this file is accessed |
| u_read | Whether current user can read this file |
| u_write | Whether current user can write to this file |
| u_exec | Whether current user can execute this file |
| g_read | Whether current user's group can read this file |
| g_write | Whether current user's group can write to this file |
| g_exec | Whether current user's group can execute this file |
| o_read | Whether other groups and users can read this file |
| o_write | Whether other groups and users can write to this file |
| o_exec | Whether other groups and users can execute this file |
| reserved | reserved for aligning to 32 bits |
Each sector with with file data has pointers to previous and next sectors in data list. Data is a 504 bytes between this 2 pointers.
| Bytes | Description |
|---|---|
| 4 bytes | Pointer to previous node (if 0 - first node) |
| 504 bytes | Data |
| 4 bytes | Pointer to next node (if 0 - last node) |
NOTICE! End of file data (FDE byte) is a byte with value 0x1C.
Current version of LIFS is 1.1. Further plans of developing is adding more flags during developing of 42IX.
You can develop and use it in terms of GNU General Public License v3.0