isabella232 / distinst

Installer Backend

distinst

Distinst is a Rust-based software library that handles Linux distribution installer installation details. It has been built specifically to be used in the construction of Linux distribution installers, so that installers can spend more time improving their UI, and less time worrying about some of the more complicated implementation details, such as partition management & encryption.

Frontends

At the moment, elementary's installer is the primary target for distinst. However, distinst also ships with a CLI application (also called distinst) that serves as a fully-functioning test bed for the distinst library. Example scripts exist within the tests directory to demonstrate how the CLI can be used to perform installs using files from the Pop! ISO.

CLI

• distinst (Rust)

GTK

• elementary Installer (Vala)

Capabilities

Disk Partitioning & Formatting

Distinst provides a Rust, C, and Vala API for probing disk and partition information, as well as the ability to create and manipulate partitions. In addition to partitioning the disk via the libparted bindings, distinst will also handle disk partitioning using mkfs, provided that you have installed the corresponding packages for each file system type that you want to support in your installer. LUKS & LVM configurations are also supported, and may be configured after configuring your physical partitions.

Implementors of the library should note that distinst utilizes in-memory partition management logic to determine whether changes that are being specified will be valid or not. Changes specified will be applied by distinst during the install method, which is where you will pass your disk configurations into. This configuration will be validated by distinst before any changes are made.

Rust Example

See the source code for the distinst CLI application.

Vala Example

if (disk.mklabel (bootloader) != 0) {
    stderr.printf ("unable to write GPT partition table to /dev/sda");
    exit (1);
}

var efi_sector = Sector() {
    flag = SectorKind.MEGABYTE,
    value = 512
};

var start = disk.get_sector (Sector.start());
var end = disk.get_sector (efi_sector);

int result = disk.add_partition(
    new PartitionBuilder (start, end, FileSystem.FAT32)
        .set_partition_type (PartitionType.PRIMARY)
        .add_flag (PartitionFlag.ESP)
        .set_mount ("/boot/efi")
);

if (result != 0) {
    stderr.printf ("unable to add EFI partition to disk");
    exit (1);
}

start = disk.get_sector (efi_sector);
end = disk.get_sector (Sector.end ());

result = disk.add_partition (
    new PartitionBuilder (start, end, FileSystem.EXT4)
        .set_partition_type (PartitionType.PRIMARY)
        .set_mount ("/")
);

if (result != 0) {
    stderr.printf ("unable to add / partition to disk");
    exit (1);
}

Disks disks = Disks.with_capacity (1);
disks.push (disk);
installer.install (disks, config);

Extracting, Chrooting, & Configuring

The implementor of the library should provide a squashfs file that contains a base image that the installer will extract during installation, as well as the accompanying .manifest-remove file. These can be found on the Pop!_OS ISOs, as an example. Once this image has been extracted, the installer will chroot into the new install and then configure the image using the configuration script located at src/configure.sh.

Bootloader

Based on whether the image is running on a system that is EFI or not, the bootloader will be configured using either systemd-boot or GRUB, thereby allowing the user to be capable of booting into install once the system is rebooted.

Build Instructions

In order to build distinst on Pop!, you will need to follow these instructions:

# Install dependencies
sudo apt build-dep distinst

# Build in debug mode
# make all DEBUG=1

# Build in release mode
make

# Install in release mode
sudo make install prefix=/usr

# Install in debug mode
# sudo make install prefix=/usr DEBUG=1

# Uninstall
sudo make uninstall

The following files will be generated:

• CLI app: target/release/distinst
• Library: target/release/libdistinst.so
• Header: target/include/distinst.h
• pkg-config: target/pkg-config/distinst.pc

These files will be placed in /usr/local when installed, and pkg-config --cflags distinst or pkg-config --libs distinst can then be used to find them.

In order to produce a source package, you must run the following commands:

# Install cargo-vendor
cargo install cargo-vendor

# Download vendored sources
make vendor