mbrman

MBR Partition Management in Rust

Library Usage

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

```rust 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.isused() { println!("Partition #{}: type = {:?}, size = {} bytes, starting lba = {}", i, p.sys, p.sectors * mbr.sectorsize, p.starting_lba); } } ```

Create and delete primary partitions

```rust 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 freepartitionnumber = mbr.iter().find(|(i, p)| p.isunused()).map(|(i, _)| i) .expect("no more places available"); let sectors = mbr.getmaximumpartitionsize() .expect("no more space available"); let startinglba = mbr.findoptimal_place(sectors) .expect("could not find a place to put the partition");

mbr[freepartitionnumber] = mbrman::MBRPartitionEntry { boot: false, // boot flag firstchs: mbrman::CHS::empty(), // first CHS address (only useful for old computers) sys: 0x83, // Linux filesystem lastchs: 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[freepartitionnumber] = 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

```rust 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

```rust 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 firstchs: mbrman::CHS::empty(), // first CHS address (only useful for old computers) sys: 0x0f, // extended partition with LBA lastchs: mbrman::CHS::empty(), // last CHS address (only useful for old computers) startinglba: 1, // the sector where the partition starts sectors: mbr.disksize - 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.

```rust 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 firstchs: mbrman::CHS::empty(), // first CHS address (only useful for old computers) sys: 0x0f, // extended partition with LBA lastchs: mbrman::CHS::empty(), // last CHS address (only useful for old computers) startinglba: 1, // the sector where the partition starts sectors: mbr.disksize - 1, // the number of sectors in that partition };

// NOTE: mbrman won't check the consistency of the partition you have created manually mbr.logicalpartitions.push( mbrman::LogicalPartition { // this is the actual partition entry for the logical volume partition: mbrman::MBRPartitionEntry { boot: false, firstchs: mbrman::CHS::empty(), sys: 0x83, lastchs: mbrman::CHS::empty(), startinglba: 2, // the sector index 1 is used by the EBR sectors: mbr.disksize - 2, }, // this is the absolute LBA address of the EBR absoluteebrlba: 1, // the number of sectors in the first EBR is never known ebrsectors: None, // this helper generates an empty boot sector in the EBR bootstrapcode: mbrman::BootstrapCode446::new(), // this is the absolute CHS address of the EBR (only used by old computers) ebrfirstchs: 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 ebrlast_chs: None, } );

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