disk_types/
table.rs

1use crate::{device::BlockDeviceExt, partition::PartitionType};
2
3/// Specifies whether the partition table on the disk is **MSDOS** or **GPT**.
4#[derive(Debug, PartialEq, Clone, Copy, Hash)]
5pub enum PartitionTable {
6    Msdos,
7    Gpt,
8}
9
10/// A possible error when validating the partition table.
11#[derive(Debug, Error, PartialEq)]
12pub enum PartitionTableError {
13    #[error(display = "primary partitions exceeded on partition table")]
14    PrimaryPartitionsExceeded,
15    #[error(display = "partition table not found")]
16    NotFound,
17}
18
19/// Methods for block devices that may have a partition table.
20pub trait PartitionTableExt: BlockDeviceExt {
21    /// Fetch the partition table info on this device, if it exists.
22    fn get_partition_table(&self) -> Option<PartitionTable>;
23
24    /// Obtain the number of primary and logical partitions, in that order.
25    fn get_partition_type_count(&self) -> (usize, usize, bool);
26
27    /// Checks if the additional partition type can be added to the partition table.
28    fn supports_additional_partition_type(
29        &self,
30        new_type: PartitionType,
31    ) -> Result<(), PartitionTableError> {
32        match self.get_partition_table() {
33            Some(PartitionTable::Gpt) => (),
34            Some(PartitionTable::Msdos) => {
35                let (primary, logical, extended) = self.get_partition_type_count();
36                if new_type == PartitionType::Primary {
37                    if primary >= 4 || (primary >= 3 && (extended || logical != 0)) {
38                        return Err(PartitionTableError::PrimaryPartitionsExceeded);
39                    }
40                } else if primary >= 4 {
41                    return Err(PartitionTableError::PrimaryPartitionsExceeded);
42                }
43            }
44            None => return Err(PartitionTableError::NotFound),
45        }
46
47        Ok(())
48    }
49}
50
51#[cfg(test)]
52mod tests {
53    use super::*;
54    use std::path::Path;
55
56    pub struct FictionalBlock {
57        partitions: Vec<PartitionType>,
58    }
59
60    impl BlockDeviceExt for FictionalBlock {
61        fn get_device_name(&self) -> &str { "fictional" }
62
63        fn get_device_path(&self) -> &Path { Path::new("/dev/fictional")  }
64
65        fn get_mount_point(&self) -> Option<&Path> { None }
66    }
67
68    impl PartitionTableExt for FictionalBlock {
69        fn get_partition_table(&self) -> Option<PartitionTable> { Some(PartitionTable::Msdos) }
70
71        fn get_partition_type_count(&self) -> (usize, usize, bool) {
72            self.partitions.iter().fold((0, 0, false), |sum, &part| match part {
73                PartitionType::Logical => (sum.0, sum.1 + 1, sum.2),
74                PartitionType::Primary => (sum.0 + 1, sum.1, sum.2),
75                PartitionType::Extended => (sum.0, sum.1, true),
76            })
77        }
78    }
79
80    #[test]
81    fn partition_table_msdos_checks() {
82        let maxed_block = FictionalBlock {
83            partitions: vec![
84                PartitionType::Primary,
85                PartitionType::Primary,
86                PartitionType::Primary,
87                PartitionType::Primary,
88            ],
89        };
90
91        assert_eq!(
92            maxed_block.supports_additional_partition_type(PartitionType::Primary),
93            Err(PartitionTableError::PrimaryPartitionsExceeded)
94        );
95
96        assert_eq!(
97            maxed_block.supports_additional_partition_type(PartitionType::Logical),
98            Err(PartitionTableError::PrimaryPartitionsExceeded)
99        );
100
101        let max_extended = FictionalBlock {
102            partitions: vec![
103                PartitionType::Primary,
104                PartitionType::Primary,
105                PartitionType::Primary,
106                PartitionType::Extended,
107                PartitionType::Logical,
108                PartitionType::Logical,
109            ],
110        };
111
112        assert_eq!(
113            max_extended.supports_additional_partition_type(PartitionType::Primary),
114            Err(PartitionTableError::PrimaryPartitionsExceeded)
115        );
116
117        assert_eq!(max_extended.supports_additional_partition_type(PartitionType::Logical), Ok(()));
118
119        let free = FictionalBlock {
120            partitions: vec![
121                PartitionType::Primary,
122                PartitionType::Primary,
123                PartitionType::Extended,
124                PartitionType::Logical,
125                PartitionType::Logical,
126            ],
127        };
128
129        assert_eq!(free.supports_additional_partition_type(PartitionType::Primary), Ok(()));
130
131        assert_eq!(free.supports_additional_partition_type(PartitionType::Logical), Ok(()));
132    }
133}
disk_types/table.rs

disk_types/
table.rs
