Improve installation and documentation (#73)

* Add kernel::fs::mount

* Check if fs is mounted before opening dir

* Save password hash during user creation

* Create home directory during user creation

* Improve path checking in mkfs

* Improve mkfs output

* Add install command

* Check presence of username and password during user creation

* Update documentation

* Check if user already exists before creation

* Split hashed_password

* Add save_hashed_password

* Rename login command to user

* Display MOROS version in a consistent way

* Use ctrl+d instead of ctrl+c to exit shell

* Rename mkfs to disk format

* Add disk list command

* Change prompt color if last command errored

* Improve installer

* Use $ and > prompts in doc

Use $ and > prompts in doc to indicate commands outside and inside
of MOROS respectively.

README.md

@@ -8,6 +8,7 @@ This project started from the [seventh post][1] of the second edition of
 
 ![screenshot](screenshot.png)
 
+
 ## Features
 
 - [x] External bootloader (using [bootloader](https://github.com/rust-osdev/bootloader))
@@ -34,39 +35,45 @@ This project started from the [seventh post][1] of the second edition of
 - [ ] Multitasking
 - [ ] A real userspace
 
+
 ## Setup
 
 Install tools:
 
-    curl https://sh.rustup.rs -sSf | sh
-    rustup install nightly
-    rustup default nightly
-    rustup component add rust-src
-    rustup component add llvm-tools-preview
-    cargo install cargo-xbuild bootimage
+    $ curl https://sh.rustup.rs -sSf | sh
+    $ rustup install nightly
+    $ rustup default nightly
+    $ rustup component add rust-src
+    $ rustup component add llvm-tools-preview
+    $ cargo install cargo-xbuild bootimage
+
 
 ## Usage
 
-Build image:
+Build image to `disk.img`:
 
-    make image output=vga keyboard=qwerty
+    $ make image output=vga keyboard=qwerty
 
 Run on QEMU:
 
-    make qemu output=vga
-
-MOROS will open a console in diskless mode after boot if no filesystem is
-detected. Use `mkfs /dev/ata/0/0` to create a filesystem on the ATA hard drive
-that will be used on the next boot.
+    $ make qemu output=vga
 
 Run on a native x86 computer by copying the bootloader and kernel to a hard
 drive or USB stick (but there is currently no USB driver so the filesystem
 will not be available):
 
-    sudo dd if=target/x86_64-moros/release/bootimage-moros.bin of=/dev/sdx && sync
+    $ sudo dd if=target/x86_64-moros/release/bootimage-moros.bin of=/dev/sdx && sync
+
+In both cases, MOROS will open a console in diskless mode after boot if no
+filesystem is detected. The following command will setup the filesystem on the
+first hard drive of the first ATA bus, allowing you to exit the diskless mode
+and log in as a normal user:
+
+    > install
 
 **Be careful not to overwrite the hard drive of your OS when using `dd` inside
-your OS or `mkfs` inside MOROS.**
+your OS, and `install` or `disk format` inside MOROS.**
+
 
 ## LICENSE
 

doc/filesystem.md

@@ -2,40 +2,83 @@
 
 ## Hard drive
 
-A hard drive is separated in block of 512 bytes, grouped into three areas. The
-first is reserved for future uses, the second is used as a bitmap mapping the
-allocated blocks in the third area. The data stored on the hard drive use the
-blocks of the third area.
-
-During the first boot of the OS, the root dir will be allocated, using the
-first block of the data area.
+A hard drive is separated in blocks of 512 bytes, grouped into 4 areas:
+
+    +------------+
+    | Boot       | (2048 blocks)
+    +------------+
+    | Superblock | (2 blocks)
+    +------------+
+    | Bitmap     | (512 blocks)
+    +------------+
+    | Data       |
+    +------------+
+
+The first area contains the bootloader and the kernel, the second is a
+superblock with a magic string to identify the file system, the third is a
+bitmap mapping the allocated data blocks of the last area.
 
 A location on the tree of dirs and files is named a path:
 
   - The root dir is represented by a slash: `/`
   - A dir inside the root will have its name appended to the slash: `/usr`
   - Subsequent dirs will append a slash and their names: `/usr/admin`
 
+
 ### Creation with QEMU
 
     $ qemu-img create disk.img 128M
     Formatting 'disk.img', fmt=raw size=134217728
 
+
 ### Setup in diskless console
 
-During boot MOROS will detect the hard drives present on the ATA buses, then
-the filesystems on those hard drives. If no filesystem is found, MOROS will
-open a console in diskless mode to allow the user to create one with the `mkfs`
-command:
+During boot MOROS will detect any hard drives present on the ATA buses, then
+look for a filesystem on those hard drives. If no filesystem is found, MOROS
+will open a console in diskless mode to allow the user to create one with
+the `disk format` command:
+
+    > disk format /dev/ata/0/0
+
+This command will format the first disk on the first ATA bus by writing a magic
+string in a superblock, mounting the filesystem, and allocating the root
+directory.
+
+The next step during setup is to create the directory structure:
+
+    > write /bin/           # Binaries
+    > write /dev/           # Devices
+    > write /ini/           # Initialisation files
+    > write /lib/           # Libraries
+    > write /net/           # Network
+    > write /src/           # Sources
+    > write /tmp/           # Temporary files
+    > write /usr/           # User directories
+    > write /var/           # Variable files
+
+Then the following should be added to the boot script with the
+command `edit /ini/boot.sh` to allow MOROS to finish booting:
 
-    > mkfs /dev/ata/0/0
+    user login
+    shell
+
+Finally a user can be created with the following command:
+
+    > user create
+
+All of this can be made more easily by running the `install` command instead.
+This installer  will also add additional files contained in the `dsk`
+repository of the source code, like a nice login banner :)
+
+
+## Data Structures
 
-## Data
 
 ### BlockBitmap
 
 Bitmap of allocated blocks in the data area.
 
+
 ### Block
 
 A block is small area of 512 bytes on a hard drive, and it is also part of
@@ -44,28 +87,71 @@ linked list representing a file or a directory.
 The first 4 bytes of a block is the address of the next block on the list and
 the rest of block is the data stored in the block.
 
+Structure:
+
+     0
+     0 1 2 3 4 5 6      n
+    +-+-+-+-+-+-+-+ // +-+
+    | addr  | data       |
+    +-+-+-+-+-+-+-+ // +-+
+
+    n = 512
+
+
 ### DirEntry
 
-A directory entry represent a file or a directory contained inside a directory.
-Each entry use a variable number of bytes that must fit inside the data of one
-block. Those bytes represent the kind of entry (file or dir), the address of
-the first block, the filesize (max 4GB), and the filename (max 255 chars) of
-the entry.
+A directory entry represents a file or a directory contained inside a
+directory. Each entry use a variable number of bytes that must fit inside the
+data of one block. Those bytes represent the kind of entry (file or dir), the
+address of the first block, the filesize (max 4GB), the length of the filename,
+and the filename (max 255 chars) of the entry.
 
 Structure:
 
-  - 0..1: kind
-  - 1..5: addr
-  - 5..10: size
-  - 10..11: name len
-  - 11..n: name buf
+     0                   1
+     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6      m
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // +-+
+    |k| addr  | size  |n| name buffer        |
+    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // +-+
+
+    k = kind of entry
+    n = length of name buffer
+    m = 9 + n
+
 
 ### Dir
 
-A directory contains the address of the first block where its directory entries
-are stored.
+The first block of a directory contains the address of the next block where its
+directory entries are stored and the first entries in the rest of the block.
+
+If all entries can fit into one block the address of the next block will be
+empty.
+
+Structure:
+
+     0                   1
+     0 1 2 3 4 5 6 7 8 9 0                            n
+    +-+-+-+-+-+-+-+-+-+-+-+ // +-+-+-+-+-+-+-+-+ // +-+
+    | addr  | dir entry 1        | dir entry 2        |
+    +-+-+-+-+-+-+-+-+-+-+-+ // +-+-+-+-+-+-+-+-+ // +-+
+
+    n = 512
+
 
 ### File
 
-A file contains the address of its first block along with its filesize and
-filename, and a reference to its parent directory.
+The first block of a contains the address of the next block where its contents
+is stored and the beginning of its contents in the rest of the block.
+
+If all contents can fit into one block the address of the next block will be
+empty.
+
+Structure:
+
+     0
+     0 1 2 3 4 5 6 7 8      n
+    +-+-+-+-+-+-+-+-+-+ // +-+
+    | addr  | contents       |
+    +-+-+-+-+-+-+-+-+-+ // +-+
+
+    n = 512