# Filesystem Layer

```mermaid
---
title: Filesystem Structures
---
classDiagram
    class vmp_t{
        block_device-t *dev_driver
        vfs_fs_t *fs_driver
        char name[16]
        uint8_t block_buff[BLOCK_DEVICE_BLOCK_SIZE]
        unsigned int mounted : 1
        unsigned int read_only : 1
        uint8_t subdev
        union fs_data
    }
    class block_device_t {
        bool_t active
        char name[16]
        uint8_t num_sub_devices

        int (*init)(block_device_t *dev)
        int (*finish)(void)

        int (*read_block)(uint32_t block_num, uint8_t *buff, uint8_t subdev)
        int (*write_block)(uint32_t block_num, uint8_t *buff, uint8_t subdev)

        void *driver_data
    }
    class vfs_fs_t {
        uint8_t type
        int (*handles_path)(const char *pathname)
        char *name
        block_device_t *dev
        vfs_t api
    }
    class fs_data <<union>> {
        ext2_fs_t   e2fs
    }

    class vfile_t {
        char path[PATH_MAX]
        bool_t open
        vmp_t *mp
        union file_fs_data
    }
    class file_fs_data <<union>> {
        ext2_file_t e2dir
    }
    class vfs.fs {
        vmp_t *(*mount)(vmp_t *mp)
        int (*unmount)(vmp_t *mp)
        int (*open)(vfile_t *pwd, const char *fname)
        int (*read)(vfile_t *file, char *buf, size_t n_bytes)
        int (*write)(vfile_t *file, const char *buf, size_t n_bytes)
        int (*close)(vfile_t *file)
    }
    class vfs.chardev {
    
    }

    block_device_t <|-- vmp_t
    vfs_fs_t <|-- vmp_t
    file_fs_data <|-- vfile_t

```

Another attempt:
```mermaid
erDiagram
    direction BT
    vmp_t:::fs ||--|| ORDER : places
    vmp_t {
        block_device-t *dev_driver
        vfs_fs_t *fs_driver
        char name[16]
        uint8_t block_buff[BLOCK_DEVICE_BLOCK_SIZE]
        unsigned int mounted
        unsigned int read_only
        uint8_t subdev
        union fs_data
    }
    ORDER {
        int orderNumber
        string deliveryAddress
    }
    vfile_t {
        char path[PATH_MAX]
        bool_t open
        vmp_t *mp
        union file_fs_data
    }

    classDef fs fill:#0ce,stroke:#333,stroke-width:4px
```
> [!NOTE]
> These diagrams are evolving as I am in the process of implementing
> the code for this. Anything could change, so come back often.