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//! Error types for Mnemo.
use thiserror::Error;
/// All errors the Mnemo engine can produce.
#[derive(Error, Debug)]
pub enum MnemoError {
/// An underlying I/O failure.
#[error("io error: {0}")]
Io(#[from] std::io::Error),
/// The file does not begin with the Mnemo magic bytes.
#[error("bad magic bytes — file is not a .mnemo database")]
BadMagic,
/// The on-disk format version is newer than this build understands.
#[error("unsupported .mnemo format version {0} (this build supports v1)")]
UnsupportedVersion(u16),
/// The header page failed its CRC check — a torn page-0 write or
/// corruption. [`crate::Mnemo::open`] tries to repair this from the WAL.
#[error("header checksum mismatch — page 0 is torn or corrupt")]
HeaderChecksum,
/// Returned when the supplied passphrase fails to unwrap the data key.
/// The failure is an authenticated-decryption failure, so it is
/// indistinguishable from a tampered key blob — both are rejected cleanly.
#[error("wrong passphrase, or the key material has been tampered with")]
WrongPassphrase,
/// AEAD authentication failed for a page: corruption or tampering.
#[error("page {0} failed authentication — the file is corrupt or tampered")]
PageAuthFailed(u64),
/// The v7 header seal failed authentication — at least one mutable
/// header field has been rewritten without the DEK. Open refuses to
/// proceed so a silent rollback or pointer-rewrite attack can't
/// surface stale data.
#[error("header seal authentication failed — mutable fields tampered with")]
HeaderTampered,
/// A low-level cryptographic operation failed.
#[error("cryptographic operation failed: {0}")]
Crypto(String),
/// Argon2id key derivation failed.
#[error("key derivation failed: {0}")]
Kdf(String),
/// A record failed to (de)serialize.
#[error("serialization error: {0}")]
Serialize(String),
/// No memory exists with the requested ID.
#[error("memory '{0}' not found")]
NotFound(String),
/// A vector did not match the database's configured dimensionality.
#[error("vector dimension mismatch: database expects {expected}, got {got}")]
DimensionMismatch {
/// Dimensionality the database was created with.
expected: usize,
/// Dimensionality of the offending vector.
got: usize,
},
/// A caller-supplied argument was invalid.
#[error("invalid argument: {0}")]
Invalid(String),
/// Another process (or another handle in this process) already holds a
/// conflicting OS file lock on the target `.mnemo` file. Write handles
/// take an exclusive lock; read-only handles take a shared lock. Two
/// writers or a writer + reader will collide.
#[error("file already locked by another handle: {path}")]
Locked {
/// The path whose lock was requested and refused.
path: std::path::PathBuf,
},
/// A mutation was attempted on a handle opened via
/// [`crate::Mnemo::open_read_only`]. Reopen read-write to mutate.
#[error("operation requires a read-write handle (this one is read-only)")]
ReadOnly,
/// A read-only open was requested but the file has pending on-disk work
/// that requires a write handle to complete — a committed-but-unchecked
/// WAL transaction, or a format-version migration older than the current
/// `VERSION`. Open read-write once, close cleanly, then reopen read-only.
#[error("read-only open blocked: {reason} — open read-write once to fix")]
NeedsWriteOpen {
/// Human-readable reason (e.g. `"pending WAL recovery"`).
reason: &'static str,
},
}
/// Convenience result alias used throughout the crate.
pub type Result<T> = std::result::Result<T, MnemoError>;