--- /dev/null
+//! Module for persisting data on-disk.
+//!
+//! The star of the show is [`KeychainStore`] which maintains an append-only file of
+//! [`KeychainChangeSet`]s which can be used to restore a [`KeychainTracker`].
+use bdk_chain::{
+ bitcoin::Transaction,
+ keychain::{KeychainChangeSet, KeychainTracker},
+ sparse_chain, AsTransaction,
+};
+use core::marker::PhantomData;
+use std::{
+ fs::{File, OpenOptions},
+ io::{self, Read, Seek, Write},
+ path::Path,
+};
+
+/// BDK File Store magic bytes length.
+pub const MAGIC_BYTES_LEN: usize = 12;
+
+/// BDK File Store magic bytes.
+pub const MAGIC_BYTES: [u8; MAGIC_BYTES_LEN] = [98, 100, 107, 102, 115, 48, 48, 48, 48, 48, 48, 48];
+
+/// Persists an append only list of `KeychainChangeSet<K,P>` to a single file.
+/// [`KeychainChangeSet<K,P>`] record the changes made to a [`KeychainTracker<K,P>`].
+#[derive(Debug)]
+pub struct KeychainStore<K, P, T = Transaction> {
+ db_file: File,
+ changeset_type_params: core::marker::PhantomData<(K, P, T)>,
+}
+
+impl<K, P, T> KeychainStore<K, P, T>
+where
+ K: Ord + Clone + core::fmt::Debug,
+ P: sparse_chain::ChainPosition,
+ T: Ord + AsTransaction + Clone,
+ KeychainChangeSet<K, P, T>: serde::Serialize + serde::de::DeserializeOwned,
+{
+ /// Creates a new store from a [`File`].
+ ///
+ /// The file must have been opened with read, write permissions.
+ ///
+ /// [`File`]: std::fs::File
+ pub fn new(mut file: File) -> Result<Self, FileError> {
+ file.rewind()?;
+
+ let mut magic_bytes = [0_u8; MAGIC_BYTES_LEN];
+ file.read_exact(&mut magic_bytes)?;
+
+ if magic_bytes != MAGIC_BYTES {
+ return Err(FileError::InvalidMagicBytes(magic_bytes));
+ }
+
+ Ok(Self {
+ db_file: file,
+ changeset_type_params: Default::default(),
+ })
+ }
+
+ /// Creates or loads a a store from `db_path`. If no file exists there it will be created.
+ pub fn new_from_path<D: AsRef<Path>>(db_path: D) -> Result<Self, FileError> {
+ let already_exists = db_path.as_ref().try_exists()?;
+
+ let mut db_file = OpenOptions::new()
+ .read(true)
+ .write(true)
+ .create(true)
+ .open(db_path)?;
+
+ if !already_exists {
+ db_file.write_all(&MAGIC_BYTES)?;
+ }
+
+ Self::new(db_file)
+ }
+
+ /// Iterates over the stored changeset from first to last changing the seek position at each
+ /// iteration.
+ ///
+ /// The iterator may fail to read an entry and therefore return an error. However the first time
+ /// it returns an error will be the last. After doing so the iterator will always yield `None`.
+ ///
+ /// **WARNING**: This method changes the write position in the underlying file. You should
+ /// always iterate over all entries until `None` is returned if you want your next write to go
+ /// at the end, otherwise you writing over existing enties.
+ pub fn iter_changesets(
+ &mut self,
+ ) -> Result<EntryIter<'_, KeychainChangeSet<K, P, T>>, io::Error> {
+ self.db_file
+ .seek(io::SeekFrom::Start(MAGIC_BYTES_LEN as _))?;
+
+ Ok(EntryIter::new(&mut self.db_file))
+ }
+
+ /// Loads all the changesets that have been stored as one giant changeset.
+ ///
+ /// This function returns a tuple of the aggregate changeset and a result which indicates
+ /// whether an error occurred while reading or deserializing one of the entries. If so the
+ /// changeset will consist of all of those it was able to read.
+ ///
+ /// You should usually check the error. In many applications it may make sense to do a full
+ /// wallet scan with a stop gap after getting an error since it is likely that one of the
+ /// changesets it was unable to read changed the derivation indicies of the tracker.
+ ///
+ /// **WARNING**: This method changes the write position of the underlying file. The next
+ /// changeset will be written over the erroring entry (or the end of the file if none existed).
+ pub fn aggregate_changeset(&mut self) -> (KeychainChangeSet<K, P, T>, Result<(), IterError>) {
+ let mut changeset = KeychainChangeSet::default();
+ let result = (|| {
+ let iter_changeset = self.iter_changesets()?;
+ for next_changeset in iter_changeset {
+ changeset.append(next_changeset?);
+ }
+ Ok(())
+ })();
+
+ (changeset, result)
+ }
+
+ /// Reads and applies all the changesets stored sequentially to tracker, stopping when it fails
+ /// to read the next one.
+ ///
+ /// **WARNING**: This method changes the write position of the underlying file. The next
+ /// changeset will be written over the erroring entry (or the end of the file if none existed).
+ pub fn load_into_keychain_tracker(
+ &mut self,
+ tracker: &mut KeychainTracker<K, P, T>,
+ ) -> Result<(), IterError> {
+ for changeset in self.iter_changesets()? {
+ tracker.apply_changeset(changeset?)
+ }
+ Ok(())
+ }
+
+ /// Append a new changeset to the file and truncate file to the end of the appended changeset.
+ ///
+ /// The truncation is to avoid the possibility of having a valid, but inconsistent changeset
+ /// directly after the appended changeset.
+ pub fn append_changeset(
+ &mut self,
+ changeset: &KeychainChangeSet<K, P, T>,
+ ) -> Result<(), io::Error> {
+ if changeset.is_empty() {
+ return Ok(());
+ }
+
+ bincode::encode_into_std_write(
+ bincode::serde::Compat(changeset),
+ &mut self.db_file,
+ bincode::config::standard(),
+ )
+ .map_err(|e| match e {
+ bincode::error::EncodeError::Io { inner, .. } => inner,
+ unexpected_err => panic!("unexpected bincode error: {}", unexpected_err),
+ })?;
+
+ // truncate file after this changeset addition
+ // if this is not done, data after this changeset may represent valid changesets, however
+ // applying those changesets on top of this one may result in inconsistent state
+ let pos = self.db_file.stream_position()?;
+ self.db_file.set_len(pos)?;
+
+ // We want to make sure that derivation indexe changes are written to disk as soon as
+ // possible so you know about the write failure before you give ou the address in the application.
+ if !changeset.derivation_indices.is_empty() {
+ self.db_file.sync_data()?;
+ }
+
+ Ok(())
+ }
+}
+
+/// Error that occurs due to problems encountered with the file.
+#[derive(Debug)]
+pub enum FileError {
+ /// IO error, this may mean that the file is too short.
+ Io(io::Error),
+ /// Magic bytes do not match expected.
+ InvalidMagicBytes([u8; MAGIC_BYTES_LEN]),
+}
+
+impl core::fmt::Display for FileError {
+ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+ match self {
+ Self::Io(e) => write!(f, "io error trying to read file: {}", e),
+ Self::InvalidMagicBytes(b) => write!(
+ f,
+ "file has invalid magic bytes: expected={:?} got={:?}",
+ MAGIC_BYTES, b
+ ),
+ }
+ }
+}
+
+impl From<io::Error> for FileError {
+ fn from(value: io::Error) -> Self {
+ Self::Io(value)
+ }
+}
+
+impl std::error::Error for FileError {}
+
+/// Error type for [`EntryIter`].
+#[derive(Debug)]
+pub enum IterError {
+ /// Failure to read from file.
+ Io(io::Error),
+ /// Failure to decode data from file.
+ Bincode(bincode::error::DecodeError),
+}
+
+impl core::fmt::Display for IterError {
+ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+ match self {
+ IterError::Io(e) => write!(f, "io error trying to read entry {}", e),
+ IterError::Bincode(e) => write!(f, "bincode error while reading entry {}", e),
+ }
+ }
+}
+
+impl std::error::Error for IterError {}
+
+/// Iterator over entries in a file store.
+///
+/// Reads and returns an entry each time [`next`] is called. If an error occurs while reading the
+/// iterator will yield a `Result::Err(_)` instead and then `None` for the next call to `next`.
+///
+/// [`next`]: Self::next
+pub struct EntryIter<'a, V> {
+ db_file: &'a mut File,
+ types: PhantomData<V>,
+ error_exit: bool,
+}
+
+impl<'a, V> EntryIter<'a, V> {
+ pub fn new(db_file: &'a mut File) -> Self {
+ Self {
+ db_file,
+ types: PhantomData,
+ error_exit: false,
+ }
+ }
+}
+
+impl<'a, V> Iterator for EntryIter<'a, V>
+where
+ V: serde::de::DeserializeOwned,
+{
+ type Item = Result<V, IterError>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let result = (|| {
+ let pos = self.db_file.stream_position()?;
+
+ match bincode::decode_from_std_read(self.db_file, bincode::config::standard()) {
+ Ok(bincode::serde::Compat(changeset)) => Ok(Some(changeset)),
+ Err(e) => {
+ if let bincode::error::DecodeError::Io { inner, .. } = &e {
+ if inner.kind() == io::ErrorKind::UnexpectedEof {
+ let eof = self.db_file.seek(io::SeekFrom::End(0))?;
+ if pos == eof {
+ return Ok(None);
+ }
+ }
+ }
+
+ self.db_file.seek(io::SeekFrom::Start(pos))?;
+ Err(IterError::Bincode(e))
+ }
+ }
+ })();
+
+ let result = result.transpose();
+
+ if let Some(Err(_)) = &result {
+ self.error_exit = true;
+ }
+
+ result
+ }
+}
+
+impl From<io::Error> for IterError {
+ fn from(value: io::Error) -> Self {
+ IterError::Io(value)
+ }
+}
--- /dev/null
+use bdk_chain::{
+ bitcoin::Transaction,
+ keychain::{KeychainChangeSet, KeychainTracker},
+ TxHeight,
+};
+use bdk_file_store::{FileError, IterError, KeychainStore, MAGIC_BYTES, MAGIC_BYTES_LEN};
+use serde;
+use std::{
+ format,
+ fs::{File, OpenOptions},
+ io::{Read, Write},
+ path::{Path, PathBuf},
+ vec::Vec,
+};
+
+struct TempPath(PathBuf);
+
+impl TempPath {
+ fn new() -> Self {
+ let now = std::time::UNIX_EPOCH
+ .elapsed()
+ .expect("must get epoch")
+ .as_nanos();
+ let mut file_path = std::env::temp_dir();
+ file_path.push(format!("bdk_test_{}", now));
+ Self(file_path)
+ }
+
+ fn open(&self) -> File {
+ OpenOptions::new()
+ .read(true)
+ .write(true)
+ .create(true)
+ .open(self.0.as_path())
+ .expect("must open")
+ }
+}
+
+impl AsRef<Path> for TempPath {
+ fn as_ref(&self) -> &Path {
+ self.0.as_path()
+ }
+}
+
+impl Drop for TempPath {
+ fn drop(&mut self) {
+ if let Err(e) = std::fs::remove_file(self.0.as_path()) {
+ if e.kind() != std::io::ErrorKind::NotFound {
+ panic!("remove file unexpected error: {}", e);
+ }
+ };
+ }
+}
+
+#[derive(
+ Debug, Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize,
+)]
+enum TestKeychain {
+ External,
+ Internal,
+}
+
+impl core::fmt::Display for TestKeychain {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ match self {
+ Self::External => write!(f, "external"),
+ Self::Internal => write!(f, "internal"),
+ }
+ }
+}
+
+#[test]
+fn magic_bytes() {
+ assert_eq!(&MAGIC_BYTES, "bdkfs0000000".as_bytes());
+}
+
+#[test]
+fn new_fails_if_file_is_too_short() {
+ let path = TempPath::new();
+ path.open()
+ .write_all(&MAGIC_BYTES[..MAGIC_BYTES_LEN - 1])
+ .expect("should write");
+
+ match KeychainStore::<TestKeychain, TxHeight, Transaction>::new(path.open()) {
+ Err(FileError::Io(e)) => assert_eq!(e.kind(), std::io::ErrorKind::UnexpectedEof),
+ unexpected => panic!("unexpected result: {:?}", unexpected),
+ };
+}
+
+#[test]
+fn new_fails_if_magic_bytes_are_invalid() {
+ let invalid_magic_mnemonic = "ldkfs0000000";
+
+ let path = TempPath::new();
+ path.open()
+ .write_all(invalid_magic_mnemonic.as_bytes())
+ .expect("should write");
+
+ match KeychainStore::<TestKeychain, TxHeight, Transaction>::new(path.open()) {
+ Err(FileError::InvalidMagicBytes(b)) => {
+ assert_eq!(b, invalid_magic_mnemonic.as_bytes())
+ }
+ unexpected => panic!("unexpected result: {:?}", unexpected),
+ };
+}
+
+#[test]
+fn append_changeset_truncates_invalid_bytes() {
+ use bdk_chain::miniscript;
+ use core::str::FromStr;
+ // initial data to write to file (magic bytes + invalid data)
+ let mut data = [255_u8; 2000];
+ data[..MAGIC_BYTES_LEN].copy_from_slice(&MAGIC_BYTES);
+
+ let descriptor = miniscript::Descriptor::from_str("tr([73c5da0a/86'/0'/0']xpub6BgBgsespWvERF3LHQu6CnqdvfEvtMcQjYrcRzx53QJjSxarj2afYWcLteoGVky7D3UKDP9QyrLprQ3VCECoY49yfdDEHGCtMMj92pReUsQ/0/*)#rg247h69").unwrap();
+ let mut tracker = KeychainTracker::<TestKeychain, TxHeight, Transaction>::default();
+ tracker.add_keychain(TestKeychain::External, descriptor);
+ let changeset = KeychainChangeSet {
+ derivation_indices: tracker
+ .txout_index
+ .reveal_to_target(&TestKeychain::External, 21)
+ .1,
+ chain_graph: Default::default(),
+ };
+
+ let path = TempPath::new();
+ path.open().write_all(&data).expect("should write");
+
+ let mut store = KeychainStore::<TestKeychain, TxHeight, Transaction>::new(path.open())
+ .expect("should open");
+ match store.iter_changesets().expect("seek should succeed").next() {
+ Some(Err(IterError::Bincode(_))) => {}
+ unexpected_res => panic!("unexpected result: {:?}", unexpected_res),
+ }
+
+ store.append_changeset(&changeset).expect("should append");
+
+ drop(store);
+
+ let got_bytes = {
+ let mut buf = Vec::new();
+ path.open().read_to_end(&mut buf).expect("should read");
+ buf
+ };
+
+ let expected_bytes = {
+ let mut buf = MAGIC_BYTES.to_vec();
+ bincode::encode_into_std_write(
+ bincode::serde::Compat(&changeset),
+ &mut buf,
+ bincode::config::standard(),
+ )
+ .expect("should encode");
+ buf
+ };
+
+ assert_eq!(got_bytes, expected_bytes);
+}
projects / bdk / commitdiff