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use crate::{device::BlockDeviceExt, partition::PartitionType};
#[derive(Debug, PartialEq, Clone, Copy, Hash)]
pub enum PartitionTable {
Msdos,
Gpt,
}
#[derive(Debug, Error, PartialEq)]
pub enum PartitionTableError {
#[error(display = "primary partitions exceeded on partition table")]
PrimaryPartitionsExceeded,
#[error(display = "partition table not found")]
NotFound,
}
pub trait PartitionTableExt: BlockDeviceExt {
fn get_partition_table(&self) -> Option<PartitionTable>;
fn get_partition_type_count(&self) -> (usize, usize, bool);
fn supports_additional_partition_type(
&self,
new_type: PartitionType,
) -> Result<(), PartitionTableError> {
match self.get_partition_table() {
Some(PartitionTable::Gpt) => (),
Some(PartitionTable::Msdos) => {
let (primary, logical, extended) = self.get_partition_type_count();
if new_type == PartitionType::Primary {
if primary >= 4 || (primary >= 3 && (extended || logical != 0)) {
return Err(PartitionTableError::PrimaryPartitionsExceeded);
}
} else if primary >= 4 {
return Err(PartitionTableError::PrimaryPartitionsExceeded);
}
}
None => return Err(PartitionTableError::NotFound),
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::path::Path;
pub struct FictionalBlock {
partitions: Vec<PartitionType>,
}
impl BlockDeviceExt for FictionalBlock {
fn get_device_name(&self) -> &str { "fictional" }
fn get_device_path(&self) -> &Path { Path::new("/dev/fictional") }
fn get_mount_point(&self) -> Option<&Path> { None }
}
impl PartitionTableExt for FictionalBlock {
fn get_partition_table(&self) -> Option<PartitionTable> { Some(PartitionTable::Msdos) }
fn get_partition_type_count(&self) -> (usize, usize, bool) {
self.partitions.iter().fold((0, 0, false), |sum, &part| match part {
PartitionType::Logical => (sum.0, sum.1 + 1, sum.2),
PartitionType::Primary => (sum.0 + 1, sum.1, sum.2),
PartitionType::Extended => (sum.0, sum.1, true),
})
}
}
#[test]
fn partition_table_msdos_checks() {
let maxed_block = FictionalBlock {
partitions: vec![
PartitionType::Primary,
PartitionType::Primary,
PartitionType::Primary,
PartitionType::Primary,
],
};
assert_eq!(
maxed_block.supports_additional_partition_type(PartitionType::Primary),
Err(PartitionTableError::PrimaryPartitionsExceeded)
);
assert_eq!(
maxed_block.supports_additional_partition_type(PartitionType::Logical),
Err(PartitionTableError::PrimaryPartitionsExceeded)
);
let max_extended = FictionalBlock {
partitions: vec![
PartitionType::Primary,
PartitionType::Primary,
PartitionType::Primary,
PartitionType::Extended,
PartitionType::Logical,
PartitionType::Logical,
],
};
assert_eq!(
max_extended.supports_additional_partition_type(PartitionType::Primary),
Err(PartitionTableError::PrimaryPartitionsExceeded)
);
assert_eq!(max_extended.supports_additional_partition_type(PartitionType::Logical), Ok(()));
let free = FictionalBlock {
partitions: vec![
PartitionType::Primary,
PartitionType::Primary,
PartitionType::Extended,
PartitionType::Logical,
PartitionType::Logical,
],
};
assert_eq!(free.supports_additional_partition_type(PartitionType::Primary), Ok(()));
assert_eq!(free.supports_additional_partition_type(PartitionType::Logical), Ok(()));
}
}