Crate mbrman

source · [−]

Expand description

A library that allows managing MBR partition tables.

Features

Create primary partitions and logical volumes
Delete primary partitions and logical volumes
Automatically generate logical volume’s EBR (or can be provided manually)
If the disk geometry is set, the partition CHS addresses will be calculated automatically when writing to disk

Examples

Read all the partitions of a disk

let mut f = std::fs::File::open("tests/fixtures/disk1.img")
    .expect("could not open disk");
let mbr = mbrman::MBR::read_from(&mut f, 512)
    .expect("could not find MBR");

println!("Disk signature: {:?}", mbr.header.disk_signature);

for (i, p) in mbr.iter() {
    // NOTE: The first four partitions are always provided by iter()
    if p.is_used() {
        println!("Partition #{}: type = {:?}, size = {} bytes, starting lba = {}",
            i,
            p.sys,
            p.sectors * mbr.sector_size,
            p.starting_lba);
    }
}

Create and delete primary partitions

let mut f = std::fs::File::open("tests/fixtures/disk1.img")
    .expect("could not open disk");
let mut mbr = mbrman::MBR::read_from(&mut f, 512)
    .expect("could not find MBR");

let free_partition_number = mbr.iter().find(|(i, p)| p.is_unused()).map(|(i, _)| i)
    .expect("no more places available");
let sectors = mbr.get_maximum_partition_size()
    .expect("no more space available");
let starting_lba = mbr.find_optimal_place(sectors)
    .expect("could not find a place to put the partition");

mbr[free_partition_number] = mbrman::MBRPartitionEntry {
    boot: false,                        // boot flag
    first_chs: mbrman::CHS::empty(),    // first CHS address (only useful for old computers)
    sys: 0x83,                          // Linux filesystem
    last_chs: mbrman::CHS::empty(),     // last CHS address (only useful for old computers)
    starting_lba,                       // the sector where the partition starts
    sectors,                            // the number of sectors in that partition
};

mbr[free_partition_number] = mbrman::MBRPartitionEntry::empty();

// NOTE: no modification is committed to the disk until we call mbr.write_into()

Create a new partition table from an empty disk

let ss = 512; // sector size
let data = vec![0; 100 * ss as usize];
let mut cur = std::io::Cursor::new(data);

let mut mbr = mbrman::MBR::new_from(&mut cur, ss as u32, [0xff; 4])
    .expect("could not create partition table");

// NOTE: commit the change to the in-memory buffer
mbr.write_into(&mut cur);

Add a new logical volume to the disk

let ss = 512; // sector size
let data = vec![0; 100 * ss as usize];
let mut cur = std::io::Cursor::new(data);

let mut mbr = mbrman::MBR::new_from(&mut cur, ss as u32, [0xff; 4])
    .expect("could not create partition table");

mbr[1] = mbrman::MBRPartitionEntry {
    boot: false,                        // boot flag
    first_chs: mbrman::CHS::empty(),    // first CHS address (only useful for old computers)
    sys: 0x0f,                          // extended partition with LBA
    last_chs: mbrman::CHS::empty(),     // last CHS address (only useful for old computers)
    starting_lba: 1,                    // the sector where the partition starts
    sectors: mbr.disk_size - 1,         // the number of sectors in that partition
};

// this helper function will do all the hard work for you
// here it creates a logical volume with Linux filesystem that occupies the entire disk
// NOTE: you will lose 1 sector because it is used by the EBR
mbr.push(0x83, 1, mbr.disk_size - 1);

// NOTE: commit the change to the in-memory buffer
mbr.write_into(&mut cur);

Add a new logical volume manually to the disk

This is useful only if you need to specify exactly where goes the EBR and the partition itself.

let ss = 512; // sector size
let data = vec![0; 100 * ss as usize];
let mut cur = std::io::Cursor::new(data);

let mut mbr = mbrman::MBR::new_from(&mut cur, ss as u32, [0xff; 4])
    .expect("could not create partition table");

mbr[1] = mbrman::MBRPartitionEntry {
    boot: false,                        // boot flag
    first_chs: mbrman::CHS::empty(),    // first CHS address (only useful for old computers)
    sys: 0x0f,                          // extended partition with LBA
    last_chs: mbrman::CHS::empty(),     // last CHS address (only useful for old computers)
    starting_lba: 1,                    // the sector where the partition starts
    sectors: mbr.disk_size - 1,         // the number of sectors in that partition
};

// NOTE: mbrman won't check the consistency of the partition you have created manually
mbr.logical_partitions.push(
    mbrman::LogicalPartition {
        // this is the actual partition entry for the logical volume
        partition: mbrman::MBRPartitionEntry {
            boot: false,
            first_chs: mbrman::CHS::empty(),
            sys: 0x83,
            last_chs: mbrman::CHS::empty(),
            starting_lba: 2,                    // the sector index 1 is used by the EBR
            sectors: mbr.disk_size - 2,
        },
        // this is the absolute LBA address of the EBR
        absolute_ebr_lba: 1,
        // the number of sectors in the first EBR is never known
        ebr_sectors: None,
        // this helper generates an empty boot sector in the EBR
        bootstrap_code: mbrman::BootstrapCode446::new(),
        // this is the absolute CHS address of the EBR (only used by old computers)
        ebr_first_chs: mbrman::CHS::empty(),                // only for old computers
        // this is the absolute CHS address of the last EBR (only used by old computers)
        // NOTE: this is not know the first EBR
        ebr_last_chs: None,
    }
);

// NOTE: commit the change to the in-memory buffer
mbr.write_into(&mut cur);