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// SPDX-License-Identifier: MIT
use crate::println;
use core::convert::TryInto;
use core::result::Result;
use fatfs::{Read, Seek};
use uuid::Uuid;
const EFI_SIGNATURE: u64 = 0x5452415020494645;
const SECTOR_SIZE: usize = 4096;
#[derive(Debug)]
pub enum Error<T> {
Io(T),
InvalidGPTHeader,
}
impl<T> From<T> for Error<T> {
fn from(err: T) -> Error<T> {
Error::Io(err)
}
}
struct TableHeader {
bytes: [u8; Self::SIZE],
my_lba: u64,
}
impl TableHeader {
const SIZE: usize = 0x5C;
fn read<R: Read + Seek>(rdr: &mut R, lba: u64) -> Result<Self, Error<R::Error>> {
let mut hdr = Self {
bytes: [0; Self::SIZE],
my_lba: lba,
};
let off = SECTOR_SIZE * (lba as usize);
rdr.seek(fatfs::SeekFrom::Start(off as u64))?;
rdr.read_exact(&mut hdr.bytes)?;
match hdr.is_valid() {
true => Ok(hdr),
false => Err(Error::InvalidGPTHeader),
}
}
fn get_signature(&self) -> u64 {
u64::from_le_bytes(self.bytes[0..8].try_into().unwrap())
}
fn get_my_lba(&self) -> u64 {
u64::from_le_bytes(self.bytes[24..32].try_into().unwrap())
}
fn get_partition_entry_lba(&self) -> u64 {
u64::from_le_bytes(self.bytes[72..80].try_into().unwrap())
}
fn get_partition_entry_count(&self) -> usize {
u32::from_le_bytes(self.bytes[80..84].try_into().unwrap()) as usize
}
fn get_partition_entry_size(&self) -> usize {
u32::from_le_bytes(self.bytes[84..88].try_into().unwrap()) as usize
}
fn is_valid(&self) -> bool {
self.get_signature() == EFI_SIGNATURE && self.get_my_lba() == self.my_lba
}
}
pub struct PartitionEntry {
bytes: [u8; Self::SIZE],
}
impl PartitionEntry {
const SIZE: usize = 0x80;
fn read<R: Read + Seek>(rdr: &mut R, off: usize) -> Result<Self, Error<R::Error>> {
let mut part = Self {
bytes: [0; Self::SIZE],
};
rdr.seek(fatfs::SeekFrom::Start(off as u64))?;
rdr.read_exact(&mut part.bytes)?;
Ok(part)
}
#[allow(dead_code)]
pub fn get_type_guid(&self) -> Uuid {
Uuid::from_bytes_le(self.bytes[0..16].try_into().unwrap())
}
pub fn get_partition_guid(&self) -> Uuid {
Uuid::from_bytes_le(self.bytes[16..32].try_into().unwrap())
}
pub fn get_starting_lba(&self) -> u64 {
u64::from_le_bytes(self.bytes[32..40].try_into().unwrap())
}
pub fn get_ending_lba(&self) -> u64 {
u64::from_le_bytes(self.bytes[40..48].try_into().unwrap())
}
pub fn get_attributes(&self) -> u64 {
u64::from_le_bytes(self.bytes[48..56].try_into().unwrap())
}
pub fn get_name(&self) -> &[u8] {
&self.bytes[56..72]
}
}
pub struct GPT<T: fatfs::ReadWriteSeek> {
disk: T,
hdr: TableHeader,
}
impl<IO: fatfs::ReadWriteSeek> GPT<IO> {
pub fn new<T: fatfs::IntoStorage<IO>>(storage: T) -> Result<Self, Error<IO::Error>> {
let mut disk = storage.into_storage();
let hdr = TableHeader::read(&mut disk, 1)?;
let gpt = Self { disk, hdr };
Ok(gpt)
}
pub fn count(&self) -> usize {
self.hdr.get_partition_entry_count()
}
pub fn index(&mut self, index: usize) -> Result<PartitionEntry, Error<IO::Error>> {
let off = (self.hdr.get_partition_entry_lba() as usize * SECTOR_SIZE)
+ index * self.hdr.get_partition_entry_size();
PartitionEntry::read(&mut self.disk, off)
}
pub fn find_by_partuuid(
&mut self,
uuid: Uuid,
) -> Result<Option<PartitionEntry>, Error<IO::Error>> {
for i in 0..self.count() {
let part = self.index(i)?;
if part.get_type_guid().is_nil() {
continue;
}
if part.get_partition_guid() == uuid {
return Ok(Some(part));
}
}
Ok(None)
}
pub fn dump(&mut self) {
for i in 0..self.count() {
let part = self.index(i).unwrap();
let guid = part.get_type_guid();
if guid.is_nil() {
continue;
}
println!(
"{}: {}..{} {:x} {:x}",
i,
part.get_starting_lba(),
part.get_ending_lba(),
guid,
part.get_partition_guid()
);
}
}
}
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