audit-trail 0.5.0

//! # audit-trail
//!
//! Tamper-evident audit logging via cryptographically chained records.
//!
//! Every audited event becomes a [`Record`] capturing the canonical
//! who / what / when / where / result tuple, together with the hash of the
//! preceding record. Any modification to a past record breaks the chain at
//! that point and is trivially detectable on re-verification.
//!
//! ## Public surface
//!
//! - [`Record`] — the audited event (5W + chain links).
//! - [`Chain`] — the append-only chain that wires a [`Hasher`], a [`Sink`],
//!   and a [`Clock`].
//! - [`Hasher`] — pluggable hash function (SHA-256, BLAKE3, …).
//! - [`Sink`] — pluggable backend that persists each record.
//! - [`Clock`] — pluggable time source.
//! - [`Verifier`] — replays a chain and proves it is untampered.
//! - [`codec`] — stable binary record encoding (`alloc` feature).
//! - [`FileSink`] / [`FileReader`] — append-only file persistence
//!   (`std` feature).
//!
//! ## Optional features
//!
//! - `std` (default) — enables `std`-dependent items ([`FileSink`],
//!   [`FileReader`]) and `std::error::Error` impls. Implies `alloc`.
//! - `alloc` — enables owned-record and in-memory sink types
//!   ([`OwnedRecord`], [`MemorySink`]) plus the [`codec`] module for
//!   serialising records to bytes.
//! - `sha2` — enables the reference [`Sha256Hasher`] backed by the `sha2`
//!   crate.
//!
//! Without any optional features, the crate ships traits, the `Chain`,
//! and the `Verifier` only — callers supply their own hasher, sink, and
//! clock.
//!
//! ## Design principles
//!
//! - **Zero-allocation hot path.** Records borrow their string fields; the
//!   append path never touches the heap.
//! - **No async runtime dependency.** The append API is synchronous.
//! - **`no_std` capable.** Enable with `default-features = false`.
//!
//! See `.dev/ROADMAP.md` for the path to 1.0.
//!
//! ## License
//!
//! Dual-licensed under Apache-2.0 OR MIT.

#![doc(html_root_url = "https://docs.rs/audit-trail")]
#![cfg_attr(docsrs, feature(doc_cfg))]
#![cfg_attr(not(feature = "std"), no_std)]
#![deny(missing_docs)]
#![deny(unsafe_op_in_unsafe_fn)]
#![deny(unused_must_use)]
#![deny(unused_results)]
#![deny(clippy::unwrap_used)]
#![deny(clippy::expect_used)]
#![deny(clippy::todo)]
#![deny(clippy::unimplemented)]
#![deny(clippy::print_stdout)]
#![deny(clippy::print_stderr)]
#![deny(clippy::dbg_macro)]
#![deny(clippy::undocumented_unsafe_blocks)]
#![deny(clippy::missing_safety_doc)]

#[cfg(feature = "alloc")]
extern crate alloc;

/// Crate version string, populated by Cargo at build time.
pub const VERSION: &str = env!("CARGO_PKG_VERSION");

mod canonical;
mod chain;
mod clock;
mod error;
mod hash;
mod record;
mod sink;
mod verify;

#[cfg(feature = "alloc")]
pub mod codec;
#[cfg(feature = "alloc")]
mod owned;
#[cfg(feature = "std")]
mod readers;
#[cfg(feature = "alloc")]
mod sinks;

#[cfg(feature = "sha2")]
mod hashers;

pub use chain::Chain;
pub use clock::{Clock, Timestamp};
pub use error::{Error, Result, SinkError};
pub use hash::{Digest, HASH_LEN, Hasher};
pub use record::{Action, Actor, Outcome, Record, RecordId, Target};
pub use sink::Sink;
pub use verify::Verifier;

#[cfg(feature = "alloc")]
#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
pub use owned::OwnedRecord;

#[cfg(feature = "alloc")]
#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
pub use sinks::MemorySink;

#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
pub use readers::FileReader;

#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
pub use sinks::FileSink;

#[cfg(feature = "sha2")]
#[cfg_attr(docsrs, doc(cfg(feature = "sha2")))]
pub use hashers::Sha256Hasher;