docs: documented USTAR implementation

.wiki/Kernel-documentation.md

@@ -304,6 +304,45 @@ This use of the vfs cache isn't a great solution and should be reworked.
 Copies **_size_** bytes from the files' cache to **_buffer_out_**.
 This won't copy more bytes than the allocated cache space is big.
 
+### fs/ustar.h
+The USTAR '_filesystem_' is probably more common known as **tar**-archive.
+It is a really simple concept, where a file consists of a header block followed by data blocks.
+These blocks are aligned at 512 bytes.
+
+OSDev Wiki: [USTAR](https://wiki.osdev.org/USTAR)
+
+#### `ustar_type_E` - enum
+The types an entry can have:
+  - **File**
+  - **Hardlink**
+  - **Symlink**
+  - **Char Device**
+  - **Block Device**
+  - **Directory**
+  - **Pipe**
+
+#### `ustar_header_T` - struct [packed / 512B aligned]
+
+| Name              | Type      | Description                                                                  |
+|-------------------|-----------|------------------------------------------------------------------------------|
+| name              | char[100] | The name of the entry                                                        |
+| mode              | uint64_t  | file mode (permissions, etc)                                                 |
+| owner_id          | uint64_t  | The owners ID                                                                |
+| group_id          | uint64_t  | The groups ID                                                                |
+| size              | char[12]  | The size of the entry, represented as a string of an octal number (dafuq)    |
+| last_modification | char[12]  | The unix-timestamp, when the entry was modified the last time                |
+| checksum          | uint64_t  | I think this is a weird checksum of the header                               |
+| type              | uint8_t   | The type (`ustar_type_E`) of the entry, represented as ascii numbers (dafuq) |
+| name_linked       | char[100] | The path to the linked entry, if this is a link-entry                        |
+| indicator         | char[6]   | This needs to be `ustar`                                                     |
+| version           | uint16_t  | The version of the **tar** command, that created the archive                 |
+| owner_user_name   | char[32]  | The name of the file owner                                                   |
+| owner_group_name  | char[32]  | The name of the file group                                                   |
+| device_major      | uint64_t  | The devices major number                                                     |
+| device_minor      | uint64_t  | The devices minor number                                                     |
+| name_prefix       | char[155] | If this is not null, this acts as a prefix for _name_                        |
+
+
 ### fs/vfs.h
 
 **VFS** stands for _Virtual File System_ and is an abstraction,
@@ -434,6 +473,13 @@ Reads **_size_** bytes from **_file_** at **_position_** into **_buffer_out_**.
 
 **Warning:** the current ramfs implementation will ignore **_position_**!
 
+#### `vfs_directory_create(filesystem, path)` - function (vfs_node_T*)
+Creates a directory at **_path_** in **_filesystem_** and returns a pointer to it.
+The directory in **_path_** needs to exist and the name of the new directory (after the last `/`) needs to not exist.
+
+#### `vfs_directory_delete(directory)` - function (void) [not implemented yet]
+Deletes a directory.
+
 #### `vfs_init(boot_info)` - function (void)
 Initializes the VFS.
 In future this will also unpack the initial ramdisk into the _temp_ directory.
@@ -441,8 +487,8 @@ In future this will also unpack the initial ramdisk into the _temp_ directory.
 #### `vfs_resolve_path(filesystem, path)` - function (vfs_node_T*)
 Returns the node at **_path_** or NULL if **_path_** is invalid.
 
-#### `vfs_unpack_archive_ustar(node, archive)` - function (void) [Not Implemented yet]
+#### `vfs_unpack_archive_ustar(filesystem, archive)` - function (void)
-This will unpack a USTAR-archive (**_archive_**) at **_node_**.
+This will unpack a USTAR-archive (**_archive_**) at **_filesystem_**'s root.
 
 ### graphics/color.h