_ Git - rust-lightning/blob - lightning-persister/src/fs_store.rs

   1 //! Objects related to [`FilesystemStore`] live here.
   2 use lightning::util::persist::KVStore;
   3 use lightning::util::string::PrintableString;
   4
   5 use std::collections::HashMap;
   6 use std::fs;
   7 use std::io::{BufReader, Read, Write};
   8 use std::path::{Path, PathBuf};
   9 use std::sync::{Arc, Mutex, RwLock};
  10
  11 #[cfg(not(target_os = "windows"))]
  12 use std::os::unix::io::AsRawFd;
  13
  14 #[cfg(target_os = "windows")]
  15 use {std::ffi::OsStr, std::os::windows::ffi::OsStrExt};
  16
  17 #[cfg(target_os = "windows")]
  18 macro_rules! call {
  19         ($e: expr) => {
  20                 if $e != 0 {
  21                         return Ok(());
  22                 } else {
  23                         return Err(std::io::Error::last_os_error());
  24                 }
  25         };
  26 }
  27
  28 #[cfg(target_os = "windows")]
  29 fn path_to_windows_str<T: AsRef<OsStr>>(path: T) -> Vec<u16> {
  30         path.as_ref().encode_wide().chain(Some(0)).collect()
  31 }
  32
  33 /// A [`KVStore`] implementation that writes to and reads from the file system.
  34 pub struct FilesystemStore {
  35         data_dir: PathBuf,
  36         locks: Mutex<HashMap<(String, String), Arc<RwLock<()>>>>,
  37 }
  38
  39 impl FilesystemStore {
  40         /// Constructs a new [`FilesystemStore`].
  41         pub fn new(data_dir: PathBuf) -> Self {
  42                 let locks = Mutex::new(HashMap::new());
  43                 Self { data_dir, locks }
  44         }
  45
  46         /// Returns the data directory.
  47         pub fn get_data_dir(&self) -> PathBuf {
  48                 self.data_dir.clone()
  49         }
  50 }
  51
  52 impl KVStore for FilesystemStore {
  53         type Reader = FilesystemReader;
  54
  55         fn read(&self, namespace: &str, key: &str) -> std::io::Result<Self::Reader> {
  56                 if key.is_empty() {
  57                         let msg = format!("Failed to read {}/{}: key may not be empty.",
  58                                 PrintableString(namespace), PrintableString(key));
  59                         return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
  60                 }
  61
  62                 if namespace.chars().any(|c| !c.is_ascii() || c.is_control()) ||
  63                         key.chars().any(|c| !c.is_ascii() || c.is_control()) {
  64                         debug_assert!(false, "Failed to read {}/{}: namespace and key must be valid ASCII
  65                                 strings.", PrintableString(namespace), PrintableString(key));
  66                         let msg = format!("Failed to read {}/{}: namespace and key must be valid ASCII strings.",
  67                                 PrintableString(namespace), PrintableString(key));
  68                         return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
  69                 }
  70
  71                 let mut outer_lock = self.locks.lock().unwrap();
  72                 let lock_key = (namespace.to_string(), key.to_string());
  73                 let inner_lock_ref = Arc::clone(&outer_lock.entry(lock_key).or_default());
  74
  75                 let mut dest_file_path = self.data_dir.clone();
  76                 dest_file_path.push(namespace);
  77                 dest_file_path.push(key);
  78                 FilesystemReader::new(dest_file_path, inner_lock_ref)
  79         }
  80
  81         fn write(&self, namespace: &str, key: &str, buf: &[u8]) -> std::io::Result<()> {
  82                 if key.is_empty() {
  83                         let msg = format!("Failed to write {}/{}: key may not be empty.",
  84                                 PrintableString(namespace), PrintableString(key));
  85                         return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
  86                 }
  87
  88                 if namespace.chars().any(|c| !c.is_ascii() || c.is_control()) ||
  89                         key.chars().any(|c| !c.is_ascii() || c.is_control()) {
  90                         debug_assert!(false, "Failed to write {}/{}: namespace and key must be valid ASCII
  91                                 strings.", PrintableString(namespace), PrintableString(key));
  92                         let msg = format!("Failed to write {}/{}: namespace and key must be valid ASCII strings.",
  93                                 PrintableString(namespace), PrintableString(key));
  94                         return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
  95                 }
  96
  97                 let mut outer_lock = self.locks.lock().unwrap();
  98                 let lock_key = (namespace.to_string(), key.to_string());
  99                 let inner_lock_ref = Arc::clone(&outer_lock.entry(lock_key).or_default());
 100                 let _guard = inner_lock_ref.write().unwrap();
 101
 102                 let mut dest_file_path = self.data_dir.clone();
 103                 dest_file_path.push(namespace);
 104                 dest_file_path.push(key);
 105
 106                 let parent_directory = dest_file_path
 107                         .parent()
 108                         .ok_or_else(|| {
 109                                 let msg =
 110                                         format!("Could not retrieve parent directory of {}.", dest_file_path.display());
 111                                 std::io::Error::new(std::io::ErrorKind::InvalidInput, msg)
 112                         })?
 113                         .to_path_buf();
 114                 fs::create_dir_all(&parent_directory)?;
 115
 116                 // Do a crazy dance with lots of fsync()s to be overly cautious here...
 117                 // We never want to end up in a state where we've lost the old data, or end up using the
 118                 // old data on power loss after we've returned.
 119                 // The way to atomically write a file on Unix platforms is:
 120                 // open(tmpname), write(tmpfile), fsync(tmpfile), close(tmpfile), rename(), fsync(dir)
 121                 let mut tmp_file_path = dest_file_path.clone();
 122                 tmp_file_path.set_extension("tmp");
 123
 124                 {
 125                         let mut tmp_file = fs::File::create(&tmp_file_path)?;
 126                         tmp_file.write_all(&buf)?;
 127                         tmp_file.sync_all()?;
 128                 }
 129
 130                 #[cfg(not(target_os = "windows"))]
 131                 {
 132                         fs::rename(&tmp_file_path, &dest_file_path)?;
 133                         let dir_file = fs::OpenOptions::new().read(true).open(&parent_directory)?;
 134                         unsafe {
 135                                 libc::fsync(dir_file.as_raw_fd());
 136                         }
 137                         Ok(())
 138                 }
 139
 140                 #[cfg(target_os = "windows")]
 141                 {
 142                         if dest_file_path.exists() {
 143                                 call!(unsafe {
 144                                         windows_sys::Win32::Storage::FileSystem::ReplaceFileW(
 145                                                 path_to_windows_str(dest_file_path).as_ptr(),
 146                                                 path_to_windows_str(tmp_file_path).as_ptr(),
 147                                                 std::ptr::null(),
 148                                                 windows_sys::Win32::Storage::FileSystem::REPLACEFILE_IGNORE_MERGE_ERRORS,
 149                                                 std::ptr::null_mut() as *const core::ffi::c_void,
 150                                                 std::ptr::null_mut() as *const core::ffi::c_void,
 151                                         )
 152                                 });
 153                         } else {
 154                                 call!(unsafe {
 155                                         windows_sys::Win32::Storage::FileSystem::MoveFileExW(
 156                                                 path_to_windows_str(tmp_file_path).as_ptr(),
 157                                                 path_to_windows_str(dest_file_path).as_ptr(),
 158                                                 windows_sys::Win32::Storage::FileSystem::MOVEFILE_WRITE_THROUGH
 159                                                         | windows_sys::Win32::Storage::FileSystem::MOVEFILE_REPLACE_EXISTING,
 160                                         )
 161                                 });
 162                         }
 163                 }
 164         }
 165
 166         fn remove(&self, namespace: &str, key: &str) -> std::io::Result<()> {
 167                 if key.is_empty() {
 168                         let msg = format!("Failed to remove {}/{}: key may not be empty.",
 169                                 PrintableString(namespace), PrintableString(key));
 170                         return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
 171                 }
 172
 173                 if namespace.chars().any(|c| !c.is_ascii() || c.is_control()) ||
 174                         key.chars().any(|c| !c.is_ascii() || c.is_control()) {
 175                         debug_assert!(false, "Failed to remove {}/{}: namespace and key must be valid ASCII
 176                                 strings.", PrintableString(namespace), PrintableString(key));
 177                         let msg = format!("Failed to remove {}/{}: namespace and key must be valid ASCII strings.",
 178                                 PrintableString(namespace), PrintableString(key));
 179                         return Err(std::io::Error::new(std::io::ErrorKind::Other, msg));
 180                 }
 181
 182                 let mut outer_lock = self.locks.lock().unwrap();
 183                 let lock_key = (namespace.to_string(), key.to_string());
 184                 let inner_lock_ref = Arc::clone(&outer_lock.entry(lock_key.clone()).or_default());
 185
 186                 let _guard = inner_lock_ref.write().unwrap();
 187
 188                 let mut dest_file_path = self.data_dir.clone();
 189                 dest_file_path.push(namespace);
 190                 dest_file_path.push(key);
 191
 192                 if !dest_file_path.is_file() {
 193                         return Ok(());
 194                 }
 195
 196                 fs::remove_file(&dest_file_path)?;
 197                 #[cfg(not(target_os = "windows"))]
 198                 {
 199                         let parent_directory = dest_file_path.parent().ok_or_else(|| {
 200                                 let msg =
 201                                         format!("Could not retrieve parent directory of {}.", dest_file_path.display());
 202                                 std::io::Error::new(std::io::ErrorKind::InvalidInput, msg)
 203                         })?;
 204                         let dir_file = fs::OpenOptions::new().read(true).open(parent_directory)?;
 205                         unsafe {
 206                                 // The above call to `fs::remove_file` corresponds to POSIX `unlink`, whose changes
 207                                 // to the inode might get cached (and hence possibly lost on crash), depending on
 208                                 // the target platform and file system.
 209                                 //
 210                                 // In order to assert we permanently removed the file in question we therefore
 211                                 // call `fsync` on the parent directory on platforms that support it,
 212                                 libc::fsync(dir_file.as_raw_fd());
 213                         }
 214                 }
 215
 216                 if dest_file_path.is_file() {
 217                         return Err(std::io::Error::new(std::io::ErrorKind::Other, "Removing key failed"));
 218                 }
 219
 220                 if Arc::strong_count(&inner_lock_ref) == 2 {
 221                         // It's safe to remove the lock entry if we're the only one left holding a strong
 222                         // reference. Checking this is necessary to ensure we continue to distribute references to the
 223                         // same lock as long as some Readers are around. However, we still want to
 224                         // clean up the table when possible.
 225                         //
 226                         // Note that this by itself is still leaky as lock entries will remain when more Readers/Writers are
 227                         // around, but is preferable to doing nothing *or* something overly complex such as
 228                         // implementing yet another RAII structure just for this pupose.
 229                         outer_lock.remove(&lock_key);
 230                 }
 231
 232                 // Garbage collect all lock entries that are not referenced anymore.
 233                 outer_lock.retain(|_, v| Arc::strong_count(&v) > 1);
 234
 235                 Ok(())
 236         }
 237
 238         fn list(&self, namespace: &str) -> std::io::Result<Vec<String>> {
 239                 let mut prefixed_dest = self.data_dir.clone();
 240                 prefixed_dest.push(namespace);
 241
 242                 let mut keys = Vec::new();
 243
 244                 if !Path::new(&prefixed_dest).exists() {
 245                         return Ok(Vec::new());
 246                 }
 247
 248                 for entry in fs::read_dir(&prefixed_dest)? {
 249                         let entry = entry?;
 250                         let p = entry.path();
 251
 252                         if !p.is_file() {
 253                                 continue;
 254                         }
 255
 256                         if let Some(ext) = p.extension() {
 257                                 if ext == "tmp" {
 258                                         continue;
 259                                 }
 260                         }
 261
 262                         if let Some(relative_path) = p.strip_prefix(&prefixed_dest).ok()
 263                                 .and_then(|p| p.to_str()) {
 264                                         if relative_path.chars().all(|c| c.is_ascii() && !c.is_control()) {
 265                                                 keys.push(relative_path.to_string())
 266                                         }
 267                         }
 268                 }
 269
 270                 Ok(keys)
 271         }
 272 }
 273
 274 /// A buffered [`Read`] implementation as returned from [`FilesystemStore::read`].
 275 pub struct FilesystemReader {
 276         inner: BufReader<fs::File>,
 277         lock_ref: Arc<RwLock<()>>,
 278 }
 279
 280 impl FilesystemReader {
 281         fn new(dest_file_path: PathBuf, lock_ref: Arc<RwLock<()>>) -> std::io::Result<Self> {
 282                 let f = fs::File::open(dest_file_path.clone())?;
 283                 let inner = BufReader::new(f);
 284                 Ok(Self { inner, lock_ref })
 285         }
 286 }
 287
 288 impl Read for FilesystemReader {
 289         fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
 290                 let _guard = self.lock_ref.read().unwrap();
 291                 self.inner.read(buf)
 292         }
 293 }
 294
 295 #[cfg(test)]
 296 mod tests {
 297         use super::*;
 298         use crate::test_utils::do_read_write_remove_list_persist;
 299
 300         #[test]
 301         fn read_write_remove_list_persist() {
 302                 let temp_path = std::env::temp_dir();
 303                 let fs_store = FilesystemStore::new(temp_path);
 304                 do_read_write_remove_list_persist(&fs_store);
 305         }
 306 }