coven_format/
version.rs

1//! Supported object formats, independent of the format selected for new objects.
2
3use crate::Error;
4
5/// The format of an object or a persisted upload attempt (Appendix C.2).
6#[derive(Clone, Copy, Debug, PartialEq, Eq)]
7pub enum FormatVersion {
8    /// format.md's first format.
9    V1,
10}
11
12impl FormatVersion {
13    /// The format selected for a new object. Retries use their recorded value.
14    pub const CURRENT: Self = Self::V1;
15
16    /// The version number written after the object's kind.
17    pub const fn number(self) -> u16 {
18        match self {
19            Self::V1 => 1,
20        }
21    }
22
23    /// The three clear bytes that start every stored object: `kind | version`.
24    pub(crate) const fn prefix(self, kind: u8) -> [u8; 3] {
25        let [high, low] = self.number().to_be_bytes();
26        [kind, high, low]
27    }
28
29    /// Read the format from a clear `kind | version` prefix, before parsing
30    /// version-specific fields. The object's decoder checks the kind separately.
31    pub fn decode(prefix: &[u8]) -> Result<Self, Error> {
32        let bytes = prefix.get(..3).ok_or(Error::Truncated)?;
33        match u16::from_be_bytes([bytes[1], bytes[2]]) {
34            1 => Ok(Self::V1),
35            version => Err(Error::UnsupportedVersion(version)),
36        }
37    }
38}
39
40/// The software version required to decode or apply an input from storage:
41/// the app schema its writes use, or the object format it is encoded in.
42/// Sync, setup and unlock all report it, so it lives with the formats.
43#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
44pub enum RequiredUpdate {
45    /// The application's schema.
46    AppSchema {
47        /// Required application schema version.
48        version: u32,
49    },
50    /// Coven's stored-object format.
51    CovenFormat {
52        /// Required object format version.
53        version: u16,
54    },
55}
56
57#[cfg(test)]
58#[path = "version_tests.rs"]
59mod tests;
coven_format/version.rs

coven_format/
version.rs
