--- /dev/null
+//! Objects related to [`FilesystemStore`] live here.
+use lightning::util::persist::KVStore;
+
+use std::collections::HashMap;
+use std::fs;
+use std::io::{BufReader, Read, Write};
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, Mutex, RwLock};
+
+#[cfg(not(target_os = "windows"))]
+use std::os::unix::io::AsRawFd;
+
+#[cfg(target_os = "windows")]
+use {std::ffi::OsStr, std::os::windows::ffi::OsStrExt};
+
+#[cfg(target_os = "windows")]
+macro_rules! call {
+ ($e: expr) => {
+ if $e != 0 {
+ return Ok(());
+ } else {
+ return Err(std::io::Error::last_os_error());
+ }
+ };
+}
+
+#[cfg(target_os = "windows")]
+fn path_to_windows_str<T: AsRef<OsStr>>(path: T) -> Vec<u16> {
+ path.as_ref().encode_wide().chain(Some(0)).collect()
+}
+
+/// A [`KVStore`] implementation that writes to and reads from the file system.
+pub struct FilesystemStore {
+ data_dir: PathBuf,
+ locks: Mutex<HashMap<(String, String), Arc<RwLock<()>>>>,
+}
+
+impl FilesystemStore {
+ /// Constructs a new [`FilesystemStore`].
+ pub fn new(data_dir: PathBuf) -> Self {
+ let locks = Mutex::new(HashMap::new());
+ Self { data_dir, locks }
+ }
+
+ /// Returns the data directory.
+ pub fn get_data_dir(&self) -> PathBuf {
+ self.data_dir.clone()
+ }
+}
+
+impl KVStore for FilesystemStore {
+ type Reader = FilesystemReader;
+
+ fn read(&self, namespace: &str, key: &str) -> std::io::Result<Self::Reader> {
+ let mut outer_lock = self.locks.lock().unwrap();
+ let lock_key = (namespace.to_string(), key.to_string());
+ let inner_lock_ref = Arc::clone(&outer_lock.entry(lock_key).or_default());
+
+ if key.is_empty() {
+ let msg = format!("Failed to read {}/{}: key may not be empty.", namespace, key);
+ return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
+ }
+
+ let mut dest_file_path = self.data_dir.clone();
+ dest_file_path.push(namespace);
+ dest_file_path.push(key);
+ FilesystemReader::new(dest_file_path, inner_lock_ref)
+ }
+
+ fn write(&self, namespace: &str, key: &str, buf: &[u8]) -> std::io::Result<()> {
+ let mut outer_lock = self.locks.lock().unwrap();
+ let lock_key = (namespace.to_string(), key.to_string());
+ let inner_lock_ref = Arc::clone(&outer_lock.entry(lock_key).or_default());
+ let _guard = inner_lock_ref.write().unwrap();
+
+ if key.is_empty() {
+ let msg = format!("Failed to write {}/{}: key may not be empty.", namespace, key);
+ return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
+ }
+
+ let mut dest_file_path = self.data_dir.clone();
+ dest_file_path.push(namespace);
+ dest_file_path.push(key);
+
+ let parent_directory = dest_file_path
+ .parent()
+ .ok_or_else(|| {
+ let msg =
+ format!("Could not retrieve parent directory of {}.", dest_file_path.display());
+ std::io::Error::new(std::io::ErrorKind::InvalidInput, msg)
+ })?
+ .to_path_buf();
+ fs::create_dir_all(&parent_directory)?;
+
+ // Do a crazy dance with lots of fsync()s to be overly cautious here...
+ // We never want to end up in a state where we've lost the old data, or end up using the
+ // old data on power loss after we've returned.
+ // The way to atomically write a file on Unix platforms is:
+ // open(tmpname), write(tmpfile), fsync(tmpfile), close(tmpfile), rename(), fsync(dir)
+ let mut tmp_file_path = dest_file_path.clone();
+ tmp_file_path.set_extension("tmp");
+
+ {
+ let mut tmp_file = fs::File::create(&tmp_file_path)?;
+ tmp_file.write_all(&buf)?;
+ tmp_file.sync_all()?;
+ }
+
+ #[cfg(not(target_os = "windows"))]
+ {
+ fs::rename(&tmp_file_path, &dest_file_path)?;
+ let dir_file = fs::OpenOptions::new().read(true).open(&parent_directory)?;
+ unsafe {
+ libc::fsync(dir_file.as_raw_fd());
+ }
+ Ok(())
+ }
+
+ #[cfg(target_os = "windows")]
+ {
+ if dest_file_path.exists() {
+ call!(unsafe {
+ windows_sys::Win32::Storage::FileSystem::ReplaceFileW(
+ path_to_windows_str(dest_file_path).as_ptr(),
+ path_to_windows_str(tmp_file_path).as_ptr(),
+ std::ptr::null(),
+ windows_sys::Win32::Storage::FileSystem::REPLACEFILE_IGNORE_MERGE_ERRORS,
+ std::ptr::null_mut() as *const core::ffi::c_void,
+ std::ptr::null_mut() as *const core::ffi::c_void,
+ )
+ });
+ } else {
+ call!(unsafe {
+ windows_sys::Win32::Storage::FileSystem::MoveFileExW(
+ path_to_windows_str(tmp_file_path).as_ptr(),
+ path_to_windows_str(dest_file_path).as_ptr(),
+ windows_sys::Win32::Storage::FileSystem::MOVEFILE_WRITE_THROUGH
+ | windows_sys::Win32::Storage::FileSystem::MOVEFILE_REPLACE_EXISTING,
+ )
+ });
+ }
+ }
+ }
+
+ fn remove(&self, namespace: &str, key: &str) -> std::io::Result<()> {
+ let mut outer_lock = self.locks.lock().unwrap();
+ let lock_key = (namespace.to_string(), key.to_string());
+ let inner_lock_ref = Arc::clone(&outer_lock.entry(lock_key.clone()).or_default());
+
+ let _guard = inner_lock_ref.write().unwrap();
+
+ if key.is_empty() {
+ let msg = format!("Failed to remove {}/{}: key may not be empty.", namespace, key);
+ return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
+ }
+
+ let mut dest_file_path = self.data_dir.clone();
+ dest_file_path.push(namespace);
+ dest_file_path.push(key);
+
+ if !dest_file_path.is_file() {
+ return Ok(());
+ }
+
+ fs::remove_file(&dest_file_path)?;
+ #[cfg(not(target_os = "windows"))]
+ {
+ let parent_directory = dest_file_path.parent().ok_or_else(|| {
+ let msg =
+ format!("Could not retrieve parent directory of {}.", dest_file_path.display());
+ std::io::Error::new(std::io::ErrorKind::InvalidInput, msg)
+ })?;
+ let dir_file = fs::OpenOptions::new().read(true).open(parent_directory)?;
+ unsafe {
+ // The above call to `fs::remove_file` corresponds to POSIX `unlink`, whose changes
+ // to the inode might get cached (and hence possibly lost on crash), depending on
+ // the target platform and file system.
+ //
+ // In order to assert we permanently removed the file in question we therefore
+ // call `fsync` on the parent directory on platforms that support it,
+ libc::fsync(dir_file.as_raw_fd());
+ }
+ }
+
+ if dest_file_path.is_file() {
+ return Err(std::io::Error::new(std::io::ErrorKind::Other, "Removing key failed"));
+ }
+
+ if Arc::strong_count(&inner_lock_ref) == 2 {
+ // It's safe to remove the lock entry if we're the only one left holding a strong
+ // reference. Checking this is necessary to ensure we continue to distribute references to the
+ // same lock as long as some Readers are around. However, we still want to
+ // clean up the table when possible.
+ //
+ // Note that this by itself is still leaky as lock entries will remain when more Readers/Writers are
+ // around, but is preferable to doing nothing *or* something overly complex such as
+ // implementing yet another RAII structure just for this pupose.
+ outer_lock.remove(&lock_key);
+ }
+
+ // Garbage collect all lock entries that are not referenced anymore.
+ outer_lock.retain(|_, v| Arc::strong_count(&v) > 1);
+
+ Ok(())
+ }
+
+ fn list(&self, namespace: &str) -> std::io::Result<Vec<String>> {
+ let mut prefixed_dest = self.data_dir.clone();
+ prefixed_dest.push(namespace);
+
+ let mut keys = Vec::new();
+
+ if !Path::new(&prefixed_dest).exists() {
+ return Ok(Vec::new());
+ }
+
+ for entry in fs::read_dir(&prefixed_dest)? {
+ let entry = entry?;
+ let p = entry.path();
+
+ if !p.is_file() {
+ continue;
+ }
+
+ if let Some(ext) = p.extension() {
+ if ext == "tmp" {
+ continue;
+ }
+ }
+
+ if let Ok(relative_path) = p.strip_prefix(&prefixed_dest) {
+ keys.push(relative_path.display().to_string())
+ }
+ }
+
+ Ok(keys)
+ }
+}
+
+/// A buffered [`Read`] implementation as returned from [`FilesystemStore::read`].
+pub struct FilesystemReader {
+ inner: BufReader<fs::File>,
+ lock_ref: Arc<RwLock<()>>,
+}
+
+impl FilesystemReader {
+ fn new(dest_file_path: PathBuf, lock_ref: Arc<RwLock<()>>) -> std::io::Result<Self> {
+ let f = fs::File::open(dest_file_path.clone())?;
+ let inner = BufReader::new(f);
+ Ok(Self { inner, lock_ref })
+ }
+}
+
+impl Read for FilesystemReader {
+ fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+ let _guard = self.lock_ref.read().unwrap();
+ self.inner.read(buf)
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use crate::test_utils::do_read_write_remove_list_persist;
+
+ #[test]
+ fn read_write_remove_list_persist() {
+ let temp_path = std::env::temp_dir();
+ let fs_store = FilesystemStore::new(temp_path);
+ do_read_write_remove_list_persist(&fs_store);
+ }
+}
projects / rust-lightning / commitdiff