add git.iim.gay/grufwub/go-store for storage backend, replacing blob.Storage

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

vendor/git.iim.gay/grufwub/go-store/kv/iterator.go

@@ -0,0 +1,64 @@
+package kv
+
+import (
+	"git.iim.gay/grufwub/go-errors"
+	"git.iim.gay/grufwub/go-store/storage"
+)
+
+var ErrIteratorClosed = errors.Define("store/kv: iterator closed")
+
+// KVIterator provides a read-only iterator to all the key-value
+// pairs in a KVStore. While the iterator is open the store is read
+// locked, you MUST release the iterator when you are finished with
+// it.
+//
+// Please note:
+// - individual iterators are NOT concurrency safe, though it is safe to
+// have multiple iterators running concurrently
+type KVIterator struct {
+	store   *KVStore // store is the linked KVStore
+	entries []storage.StorageEntry
+	index   int
+	key     string
+	onClose func()
+}
+
+// Next attempts to set the next key-value pair, the
+// return value is if there was another pair remaining
+func (i *KVIterator) Next() bool {
+	next := i.index + 1
+	if next >= len(i.entries) {
+		i.key = ""
+		return false
+	}
+	i.key = i.entries[next].Key()
+	i.index = next
+	return true
+}
+
+// Key returns the next key from the store
+func (i *KVIterator) Key() string {
+	return i.key
+}
+
+// Release releases the KVIterator and KVStore's read lock
+func (i *KVIterator) Release() {
+	// Reset key, path, entries
+	i.store = nil
+	i.key = ""
+	i.entries = nil
+
+	// Perform requested callback
+	i.onClose()
+}
+
+// Value returns the next value from the KVStore
+func (i *KVIterator) Value() ([]byte, error) {
+	// Check store isn't closed
+	if i.store == nil {
+		return nil, ErrIteratorClosed
+	}
+
+	// Attempt to fetch from store
+	return i.store.get(i.key)
+}

vendor/git.iim.gay/grufwub/go-store/kv/state.go

@@ -0,0 +1,125 @@
+package kv
+
+import (
+	"io"
+
+	"git.iim.gay/grufwub/go-errors"
+)
+
+var ErrStateClosed = errors.Define("store/kv: state closed")
+
+// StateRO provides a read-only window to the store. While this
+// state is active during the Read() function window, the entire
+// store will be read-locked. The state is thread-safe for concurrent
+// use UNTIL the moment that your supplied function to Read() returns,
+// then the state has zero guarantees
+type StateRO struct {
+	store *KVStore
+}
+
+func (st *StateRO) Get(key string) ([]byte, error) {
+	// Check not closed
+	if st.store == nil {
+		return nil, ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.get(key)
+}
+
+func (st *StateRO) GetStream(key string) (io.ReadCloser, error) {
+	// Check not closed
+	if st.store == nil {
+		return nil, ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.getStream(key)
+}
+
+func (st *StateRO) Has(key string) (bool, error) {
+	// Check not closed
+	if st.store == nil {
+		return false, ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.has(key)
+}
+
+func (st *StateRO) close() {
+	st.store = nil
+}
+
+// StateRW provides a read-write window to the store. While this
+// state is active during the Update() function window, the entire
+// store will be locked. The state is thread-safe for concurrent
+// use UNTIL the moment that your supplied function to Update() returns,
+// then the state has zero guarantees
+type StateRW struct {
+	store *KVStore
+}
+
+func (st *StateRW) Get(key string) ([]byte, error) {
+	// Check not closed
+	if st.store == nil {
+		return nil, ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.get(key)
+}
+
+func (st *StateRW) GetStream(key string) (io.ReadCloser, error) {
+	// Check not closed
+	if st.store == nil {
+		return nil, ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.getStream(key)
+}
+
+func (st *StateRW) Put(key string, value []byte) error {
+	// Check not closed
+	if st.store == nil {
+		return ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.put(key, value)
+}
+
+func (st *StateRW) PutStream(key string, r io.Reader) error {
+	// Check not closed
+	if st.store == nil {
+		return ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.putStream(key, r)
+}
+
+func (st *StateRW) Has(key string) (bool, error) {
+	// Check not closed
+	if st.store == nil {
+		return false, ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.has(key)
+}
+
+func (st *StateRW) Delete(key string) error {
+	// Check not closed
+	if st.store == nil {
+		return ErrStateClosed
+	}
+
+	// Pass request to store
+	return st.store.delete(key)
+}
+
+func (st *StateRW) close() {
+	st.store = nil
+}

vendor/git.iim.gay/grufwub/go-store/kv/store.go

@@ -0,0 +1,243 @@
+package kv
+
+import (
+	"io"
+	"sync"
+
+	"git.iim.gay/grufwub/go-mutexes"
+	"git.iim.gay/grufwub/go-store/storage"
+	"git.iim.gay/grufwub/go-store/util"
+)
+
+// KVStore is a very simple, yet performant key-value store
+type KVStore struct {
+	mutexMap mutexes.MutexMap // mutexMap is a map of keys to mutexes to protect file access
+	mutex    sync.RWMutex     // mutex is the total store mutex
+	storage  storage.Storage  // storage is the underlying storage
+}
+
+func OpenFile(path string, cfg *storage.DiskConfig) (*KVStore, error) {
+	// Attempt to open disk storage
+	storage, err := storage.OpenFile(path, cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	// Return new KVStore
+	return OpenStorage(storage)
+}
+
+func OpenBlock(path string, cfg *storage.BlockConfig) (*KVStore, error) {
+	// Attempt to open block storage
+	storage, err := storage.OpenBlock(path, cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	// Return new KVStore
+	return OpenStorage(storage)
+}
+
+func OpenStorage(storage storage.Storage) (*KVStore, error) {
+	// Perform initial storage clean
+	err := storage.Clean()
+	if err != nil {
+		return nil, err
+	}
+
+	// Return new KVStore
+	return &KVStore{
+		mutexMap: mutexes.NewMap(mutexes.NewRW),
+		mutex:    sync.RWMutex{},
+		storage:  storage,
+	}, nil
+}
+
+// Get fetches the bytes for supplied key in the store
+func (st *KVStore) Get(key string) ([]byte, error) {
+	// Acquire store read lock
+	st.mutex.RLock()
+	defer st.mutex.RUnlock()
+
+	// Pass to unprotected fn
+	return st.get(key)
+}
+
+func (st *KVStore) get(key string) ([]byte, error) {
+	// Acquire read lock for key
+	runlock := st.mutexMap.RLock(key)
+	defer runlock()
+
+	// Read file bytes
+	return st.storage.ReadBytes(key)
+}
+
+// GetStream fetches a ReadCloser for the bytes at the supplied key location in the store
+func (st *KVStore) GetStream(key string) (io.ReadCloser, error) {
+	// Acquire store read lock
+	st.mutex.RLock()
+	defer st.mutex.RUnlock()
+
+	// Pass to unprotected fn
+	return st.getStream(key)
+}
+
+func (st *KVStore) getStream(key string) (io.ReadCloser, error) {
+	// Acquire read lock for key
+	runlock := st.mutexMap.RLock(key)
+
+	// Attempt to open stream for read
+	rd, err := st.storage.ReadStream(key)
+	if err != nil {
+		runlock()
+		return nil, err
+	}
+
+	// Wrap readcloser in our own callback closer
+	return util.ReadCloserWithCallback(rd, runlock), nil
+}
+
+// Put places the bytes at the supplied key location in the store
+func (st *KVStore) Put(key string, value []byte) error {
+	// Acquire store write lock
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+
+	// Pass to unprotected fn
+	return st.put(key, value)
+}
+
+func (st *KVStore) put(key string, value []byte) error {
+	// Acquire write lock for key
+	unlock := st.mutexMap.Lock(key)
+	defer unlock()
+
+	// Write file bytes
+	return st.storage.WriteBytes(key, value)
+}
+
+// PutStream writes the bytes from the supplied Reader at the supplied key location in the store
+func (st *KVStore) PutStream(key string, r io.Reader) error {
+	// Acquire store write lock
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+
+	// Pass to unprotected fn
+	return st.putStream(key, r)
+}
+
+func (st *KVStore) putStream(key string, r io.Reader) error {
+	// Acquire write lock for key
+	unlock := st.mutexMap.Lock(key)
+	defer unlock()
+
+	// Write file stream
+	return st.storage.WriteStream(key, r)
+}
+
+// Has checks whether the supplied key exists in the store
+func (st *KVStore) Has(key string) (bool, error) {
+	// Acquire store read lock
+	st.mutex.RLock()
+	defer st.mutex.RUnlock()
+
+	// Pass to unprotected fn
+	return st.has(key)
+}
+
+func (st *KVStore) has(key string) (bool, error) {
+	// Acquire read lock for key
+	runlock := st.mutexMap.RLock(key)
+	defer runlock()
+
+	// Stat file on disk
+	return st.storage.Stat(key)
+}
+
+// Delete removes the supplied key-value pair from the store
+func (st *KVStore) Delete(key string) error {
+	// Acquire store write lock
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+
+	// Pass to unprotected fn
+	return st.delete(key)
+}
+
+func (st *KVStore) delete(key string) error {
+	// Acquire write lock for key
+	unlock := st.mutexMap.Lock(key)
+	defer unlock()
+
+	// Remove file from disk
+	return st.storage.Remove(key)
+}
+
+// Iterator returns an Iterator for key-value pairs in the store, using supplied match function
+func (st *KVStore) Iterator(matchFn func(string) bool) (*KVIterator, error) {
+	// If no function, match all
+	if matchFn == nil {
+		matchFn = func(string) bool { return true }
+	}
+
+	// Get store read lock
+	st.mutex.RLock()
+
+	// Setup the walk keys function
+	entries := []storage.StorageEntry{}
+	walkFn := func(entry storage.StorageEntry) {
+		// Ignore unmatched entries
+		if !matchFn(entry.Key()) {
+			return
+		}
+
+		// Add to entries
+		entries = append(entries, entry)
+	}
+
+	// Walk keys in the storage
+	err := st.storage.WalkKeys(&storage.WalkKeysOptions{WalkFn: walkFn})
+	if err != nil {
+		st.mutex.RUnlock()
+		return nil, err
+	}
+
+	// Return new iterator
+	return &KVIterator{
+		store:   st,
+		entries: entries,
+		index:   -1,
+		key:     "",
+		onClose: st.mutex.RUnlock,
+	}, nil
+}
+
+// Read provides a read-only window to the store, holding it in a read-locked state until
+// the supplied function returns
+func (st *KVStore) Read(do func(*StateRO)) {
+	// Get store read lock
+	st.mutex.RLock()
+	defer st.mutex.RUnlock()
+
+	// Create new store state (defer close)
+	state := &StateRO{store: st}
+	defer state.close()
+
+	// Pass state
+	do(state)
+}
+
+// Update provides a read-write window to the store, holding it in a read-write-locked state
+// until the supplied functions returns
+func (st *KVStore) Update(do func(*StateRW)) {
+	// Get store lock
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+
+	// Create new store state (defer close)
+	state := &StateRW{store: st}
+	defer state.close()
+
+	// Pass state
+	do(state)
+}

vendor/git.iim.gay/grufwub/go-store/storage/block.go

@@ -0,0 +1,785 @@
+package storage
+
+import (
+	"crypto/sha256"
+	"io"
+	"io/fs"
+	"os"
+	"strings"
+	"sync"
+	"syscall"
+
+	"git.iim.gay/grufwub/fastpath"
+	"git.iim.gay/grufwub/go-bytes"
+	"git.iim.gay/grufwub/go-errors"
+	"git.iim.gay/grufwub/go-hashenc"
+	"git.iim.gay/grufwub/go-store/util"
+)
+
+var (
+	nodePathPrefix  = "node/"
+	blockPathPrefix = "block/"
+)
+
+// DefaultBlockConfig is the default BlockStorage configuration
+var DefaultBlockConfig = &BlockConfig{
+	BlockSize:    1024 * 16,
+	WriteBufSize: 4096,
+	Overwrite:    false,
+	Compression:  NoCompression(),
+}
+
+// BlockConfig defines options to be used when opening a BlockStorage
+type BlockConfig struct {
+	// BlockSize is the chunking size to use when splitting and storing blocks of data
+	BlockSize int
+
+	// WriteBufSize is the buffer size to use when writing file streams (PutStream)
+	WriteBufSize int
+
+	// Overwrite allows overwriting values of stored keys in the storage
+	Overwrite bool
+
+	// Compression is the Compressor to use when reading / writing files, default is no compression
+	Compression Compressor
+}
+
+// getBlockConfig returns a valid BlockConfig for supplied ptr
+func getBlockConfig(cfg *BlockConfig) BlockConfig {
+	// If nil, use default
+	if cfg == nil {
+		cfg = DefaultBlockConfig
+	}
+
+	// Assume nil compress == none
+	if cfg.Compression == nil {
+		cfg.Compression = NoCompression()
+	}
+
+	// Assume 0 chunk size == use default
+	if cfg.BlockSize < 1 {
+		cfg.BlockSize = DefaultBlockConfig.BlockSize
+	}
+
+	// Assume 0 buf size == use default
+	if cfg.WriteBufSize < 1 {
+		cfg.WriteBufSize = DefaultDiskConfig.WriteBufSize
+	}
+
+	// Return owned config copy
+	return BlockConfig{
+		BlockSize:    cfg.BlockSize,
+		WriteBufSize: cfg.WriteBufSize,
+		Overwrite:    cfg.Overwrite,
+		Compression:  cfg.Compression,
+	}
+}
+
+// BlockStorage is a Storage implementation that stores input data as chunks on
+// a filesystem. Each value is chunked into blocks of configured size and these
+// blocks are stored with name equal to their base64-encoded SHA256 hash-sum. A
+// "node" file is finally created containing an array of hashes contained within
+// this value
+type BlockStorage struct {
+	path      string      // path is the root path of this store
+	blockPath string      // blockPath is the joined root path + block path prefix
+	nodePath  string      // nodePath is the joined root path + node path prefix
+	config    BlockConfig // cfg is the supplied configuration for this store
+	hashPool  sync.Pool   // hashPool is this store's hashEncoder pool
+
+	// NOTE:
+	// BlockStorage does not need to lock each of the underlying block files
+	// as the filename itself directly relates to the contents. If there happens
+	// to be an overwrite, it will just be of the same data since the filename is
+	// the hash of the data.
+}
+
+// OpenBlock opens a BlockStorage instance for given folder path and configuration
+func OpenBlock(path string, cfg *BlockConfig) (*BlockStorage, error) {
+	// Acquire path builder
+	pb := util.AcquirePathBuilder()
+	defer util.ReleasePathBuilder(pb)
+
+	// Clean provided path, ensure ends in '/' (should
+	// be dir, this helps with file path trimming later)
+	path = pb.Clean(path) + "/"
+
+	// Get checked config
+	config := getBlockConfig(cfg)
+
+	// Attempt to open path
+	file, err := os.OpenFile(path, defaultFileROFlags, defaultDirPerms)
+	if err != nil {
+		// If not a not-exist error, return
+		if !os.IsNotExist(err) {
+			return nil, err
+		}
+
+		// Attempt to make store path dirs
+		err = os.MkdirAll(path, defaultDirPerms)
+		if err != nil {
+			return nil, err
+		}
+
+		// Reopen dir now it's been created
+		file, err = os.OpenFile(path, defaultFileROFlags, defaultDirPerms)
+		if err != nil {
+			return nil, err
+		}
+	}
+	defer file.Close()
+
+	// Double check this is a dir (NOT a file!)
+	stat, err := file.Stat()
+	if err != nil {
+		return nil, err
+	} else if !stat.IsDir() {
+		return nil, errPathIsFile
+	}
+
+	// Return new BlockStorage
+	return &BlockStorage{
+		path:      path,
+		blockPath: pb.Join(path, blockPathPrefix),
+		nodePath:  pb.Join(path, nodePathPrefix),
+		config:    config,
+		hashPool: sync.Pool{
+			New: func() interface{} {
+				return newHashEncoder()
+			},
+		},
+	}, nil
+}
+
+// Clean implements storage.Clean()
+func (st *BlockStorage) Clean() error {
+	nodes := map[string]*node{}
+
+	// Acquire path builder
+	pb := fastpath.AcquireBuilder()
+	defer fastpath.ReleaseBuilder(pb)
+
+	// Walk nodes dir for entries
+	onceErr := errors.OnceError{}
+	err := util.WalkDir(pb, st.nodePath, func(npath string, fsentry fs.DirEntry) {
+		// Only deal with regular files
+		if !fsentry.Type().IsRegular() {
+			return
+		}
+
+		// Stop if we hit error previously
+		if onceErr.IsSet() {
+			return
+		}
+
+		// Get joined node path name
+		npath = pb.Join(npath, fsentry.Name())
+
+		// Attempt to open RO file
+		file, err := open(npath, defaultFileROFlags)
+		if err != nil {
+			onceErr.Store(err)
+			return
+		}
+		defer file.Close()
+
+		// Alloc new Node + acquire hash buffer for writes
+		hbuf := util.AcquireBuffer(encodedHashLen)
+		defer util.ReleaseBuffer(hbuf)
+		node := node{}
+
+		// Write file contents to node
+		_, err = io.CopyBuffer(
+			&nodeWriter{
+				node: &node,
+				buf:  hbuf,
+			},
+			file,
+			nil,
+		)
+		if err != nil {
+			onceErr.Store(err)
+			return
+		}
+
+		// Append to nodes slice
+		nodes[fsentry.Name()] = &node
+	})
+
+	// Handle errors (though nodePath may not have been created yet)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	} else if onceErr.IsSet() {
+		return onceErr.Load()
+	}
+
+	// Walk blocks dir for entries
+	onceErr.Reset()
+	err = util.WalkDir(pb, st.blockPath, func(bpath string, fsentry fs.DirEntry) {
+		// Only deal with regular files
+		if !fsentry.Type().IsRegular() {
+			return
+		}
+
+		// Stop if we hit error previously
+		if onceErr.IsSet() {
+			return
+		}
+
+		inUse := false
+		for key, node := range nodes {
+			if node.removeHash(fsentry.Name()) {
+				if len(node.hashes) < 1 {
+					// This node contained hash, and after removal is now empty.
+					// Remove this node from our tracked nodes slice
+					delete(nodes, key)
+				}
+				inUse = true
+			}
+		}
+
+		// Block hash is used by node
+		if inUse {
+			return
+		}
+
+		// Get joined block path name
+		bpath = pb.Join(bpath, fsentry.Name())
+
+		// Remove this unused block path
+		err := os.Remove(bpath)
+		if err != nil {
+			onceErr.Store(err)
+			return
+		}
+	})
+
+	// Handle errors (though blockPath may not have been created yet)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	} else if onceErr.IsSet() {
+		return onceErr.Load()
+	}
+
+	// If there are nodes left at this point, they are corrupt
+	// (i.e. they're referencing block hashes that don't exist)
+	if len(nodes) > 0 {
+		nodeKeys := []string{}
+		for key := range nodes {
+			nodeKeys = append(nodeKeys, key)
+		}
+		return errCorruptNodes.Extend("%v", nodeKeys)
+	}
+
+	return nil
+}
+
+// ReadBytes implements Storage.ReadBytes()
+func (st *BlockStorage) ReadBytes(key string) ([]byte, error) {
+	// Get stream reader for key
+	rc, err := st.ReadStream(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// Read all bytes and return
+	return io.ReadAll(rc)
+}
+
+// ReadStream implements Storage.ReadStream()
+func (st *BlockStorage) ReadStream(key string) (io.ReadCloser, error) {
+	// Get node file path for key
+	npath, err := st.nodePathForKey(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// Attempt to open RO file
+	file, err := open(npath, defaultFileROFlags)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	// Alloc new Node + acquire hash buffer for writes
+	hbuf := util.AcquireBuffer(encodedHashLen)
+	defer util.ReleaseBuffer(hbuf)
+	node := node{}
+
+	// Write file contents to node
+	_, err = io.CopyBuffer(
+		&nodeWriter{
+			node: &node,
+			buf:  hbuf,
+		},
+		file,
+		nil,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// Return new block reader
+	return util.NopReadCloser(&blockReader{
+		storage: st,
+		node:    &node,
+	}), nil
+}
+
+func (st *BlockStorage) readBlock(key string) ([]byte, error) {
+	// Get block file path for key
+	bpath := st.blockPathForKey(key)
+
+	// Attempt to open RO file
+	file, err := open(bpath, defaultFileROFlags)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	// Wrap the file in a compressor
+	cFile, err := st.config.Compression.Reader(file)
+	if err != nil {
+		return nil, err
+	}
+	defer cFile.Close()
+
+	// Read the entire file
+	return io.ReadAll(cFile)
+}
+
+// WriteBytes implements Storage.WriteBytes()
+func (st *BlockStorage) WriteBytes(key string, value []byte) error {
+	return st.WriteStream(key, bytes.NewReader(value))
+}
+
+// WriteStream implements Storage.WriteStream()
+func (st *BlockStorage) WriteStream(key string, r io.Reader) error {
+	// Get node file path for key
+	npath, err := st.nodePathForKey(key)
+	if err != nil {
+		return err
+	}
+
+	// Check if this exists
+	ok, err := stat(key)
+	if err != nil {
+		return err
+	}
+
+	// Check if we allow overwrites
+	if ok && !st.config.Overwrite {
+		return ErrAlreadyExists
+	}
+
+	// Ensure nodes dir (and any leading up to) exists
+	err = os.MkdirAll(st.nodePath, defaultDirPerms)
+	if err != nil {
+		return err
+	}
+
+	// Ensure blocks dir (and any leading up to) exists
+	err = os.MkdirAll(st.blockPath, defaultDirPerms)
+	if err != nil {
+		return err
+	}
+
+	// Alloc new node
+	node := node{}
+
+	// Acquire HashEncoder
+	hc := st.hashPool.Get().(*hashEncoder)
+	defer st.hashPool.Put(hc)
+
+	// Create new waitgroup and OnceError for
+	// goroutine error tracking and propagating
+	wg := sync.WaitGroup{}
+	onceErr := errors.OnceError{}
+
+loop:
+	for !onceErr.IsSet() {
+		// Fetch new buffer for this loop
+		buf := util.AcquireBuffer(st.config.BlockSize)
+		buf.Grow(st.config.BlockSize)
+
+		// Read next chunk
+		n, err := io.ReadFull(r, buf.B)
+		switch err {
+		case nil, io.ErrUnexpectedEOF:
+			// do nothing
+		case io.EOF:
+			util.ReleaseBuffer(buf)
+			break loop
+		default:
+			util.ReleaseBuffer(buf)
+			return err
+		}
+
+		// Hash the encoded data
+		sum := hc.EncodeSum(buf.B)
+
+		// Append to the node's hashes
+		node.hashes = append(node.hashes, sum.String())
+
+		// If already on disk, skip
+		has, err := st.statBlock(sum.StringPtr())
+		if err != nil {
+			util.ReleaseBuffer(buf)
+			return err
+		} else if has {
+			util.ReleaseBuffer(buf)
+			continue loop
+		}
+
+		// Write in separate goroutine
+		wg.Add(1)
+		go func() {
+			// Defer buffer release + signal done
+			defer func() {
+				util.ReleaseBuffer(buf)
+				wg.Done()
+			}()
+
+			// Write block to store at hash
+			err = st.writeBlock(sum.StringPtr(), buf.B[:n])
+			if err != nil {
+				onceErr.Store(err)
+				return
+			}
+		}()
+
+		// We reached EOF
+		if n < buf.Len() {
+			break loop
+		}
+	}
+
+	// Wait, check errors
+	wg.Wait()
+	if onceErr.IsSet() {
+		return onceErr.Load()
+	}
+
+	// If no hashes created, return
+	if len(node.hashes) < 1 {
+		return errNoHashesWritten
+	}
+
+	// Prepare to swap error if need-be
+	errSwap := errSwapNoop
+
+	// Build file RW flags
+	// NOTE: we performed an initial check for
+	//       this before writing blocks, but if
+	//       the utilizer of this storage didn't
+	//       correctly mutex protect this key then
+	//       someone may have beaten us to the
+	//       punch at writing the node file.
+	flags := defaultFileRWFlags
+	if !st.config.Overwrite {
+		flags |= syscall.O_EXCL
+
+		// Catch + replace err exist
+		errSwap = errSwapExist
+	}
+
+	// Attempt to open RW file
+	file, err := open(npath, flags)
+	if err != nil {
+		return errSwap(err)
+	}
+	defer file.Close()
+
+	// Acquire write buffer
+	buf := util.AcquireBuffer(st.config.WriteBufSize)
+	defer util.ReleaseBuffer(buf)
+	buf.Grow(st.config.WriteBufSize)
+
+	// Finally, write data to file
+	_, err = io.CopyBuffer(file, &nodeReader{node: &node}, nil)
+	return err
+}
+
+// writeBlock writes the block with hash and supplied value to the filesystem
+func (st *BlockStorage) writeBlock(hash string, value []byte) error {
+	// Get block file path for key
+	bpath := st.blockPathForKey(hash)
+
+	// Attempt to open RW file
+	file, err := open(bpath, defaultFileRWFlags)
+	if err != nil {
+		if err == ErrAlreadyExists {
+			err = nil /* race issue describe in struct NOTE */
+		}
+		return err
+	}
+	defer file.Close()
+
+	// Wrap the file in a compressor
+	cFile, err := st.config.Compression.Writer(file)
+	if err != nil {
+		return err
+	}
+	defer cFile.Close()
+
+	// Write value to file
+	_, err = cFile.Write(value)
+	return err
+}
+
+// statBlock checks for existence of supplied block hash
+func (st *BlockStorage) statBlock(hash string) (bool, error) {
+	return stat(st.blockPathForKey(hash))
+}
+
+// Stat implements Storage.Stat()
+func (st *BlockStorage) Stat(key string) (bool, error) {
+	// Get node file path for key
+	kpath, err := st.nodePathForKey(key)
+	if err != nil {
+		return false, err
+	}
+
+	// Check for file on disk
+	return stat(kpath)
+}
+
+// Remove implements Storage.Remove()
+func (st *BlockStorage) Remove(key string) error {
+	// Get node file path for key
+	kpath, err := st.nodePathForKey(key)
+	if err != nil {
+		return err
+	}
+
+	// Attempt to remove file
+	return os.Remove(kpath)
+}
+
+// WalkKeys implements Storage.WalkKeys()
+func (st *BlockStorage) WalkKeys(opts *WalkKeysOptions) error {
+	// Acquire path builder
+	pb := fastpath.AcquireBuilder()
+	defer fastpath.ReleaseBuilder(pb)
+
+	// Walk dir for entries
+	return util.WalkDir(pb, st.nodePath, func(npath string, fsentry fs.DirEntry) {
+		// Only deal with regular files
+		if fsentry.Type().IsRegular() {
+			opts.WalkFn(entry(fsentry.Name()))
+		}
+	})
+}
+
+// nodePathForKey calculates the node file path for supplied key
+func (st *BlockStorage) nodePathForKey(key string) (string, error) {
+	// Path separators are illegal
+	if strings.Contains(key, "/") {
+		return "", ErrInvalidKey
+	}
+
+	// Acquire path builder
+	pb := util.AcquirePathBuilder()
+	defer util.ReleasePathBuilder(pb)
+
+	// Return joined + cleaned node-path
+	return pb.Join(st.nodePath, key), nil
+}
+
+// blockPathForKey calculates the block file path for supplied hash
+func (st *BlockStorage) blockPathForKey(hash string) string {
+	pb := util.AcquirePathBuilder()
+	defer util.ReleasePathBuilder(pb)
+	return pb.Join(st.blockPath, hash)
+}
+
+// hashSeparator is the separating byte between block hashes
+const hashSeparator = byte(':')
+
+// node represents the contents of a node file in storage
+type node struct {
+	hashes []string
+}
+
+// removeHash attempts to remove supplied block hash from the node's hash array
+func (n *node) removeHash(hash string) bool {
+	haveDropped := false
+	for i := 0; i < len(n.hashes); {
+		if n.hashes[i] == hash {
+			// Drop this hash from slice
+			n.hashes = append(n.hashes[:i], n.hashes[i+1:]...)
+			haveDropped = true
+		} else {
+			// Continue iter
+			i++
+		}
+	}
+	return haveDropped
+}
+
+// nodeReader is an io.Reader implementation for the node file representation,
+// which is useful when calculated node file is being written to the store
+type nodeReader struct {
+	node *node
+	idx  int
+	last int
+}
+
+func (r *nodeReader) Read(b []byte) (int, error) {
+	n := 0
+
+	// '-1' means we missed writing
+	// hash separator on last iteration
+	if r.last == -1 {
+		b[n] = hashSeparator
+		n++
+		r.last = 0
+	}
+
+	for r.idx < len(r.node.hashes) {
+		hash := r.node.hashes[r.idx]
+
+		// Copy into buffer + update read count
+		m := copy(b[n:], hash[r.last:])
+		n += m
+
+		// If incomplete copy, return here
+		if m < len(hash)-r.last {
+			r.last = m
+			return n, nil
+		}
+
+		// Check we can write last separator
+		if n == len(b) {
+			r.last = -1
+			return n, nil
+		}
+
+		// Write separator, iter, reset
+		b[n] = hashSeparator
+		n++
+		r.idx++
+		r.last = 0
+	}
+
+	// We reached end of hashes
+	return n, io.EOF
+}
+
+// nodeWriter is an io.Writer implementation for the node file representation,
+// which is useful when calculated node file is being read from the store
+type nodeWriter struct {
+	node *node
+	buf  *bytes.Buffer
+}
+
+func (w *nodeWriter) Write(b []byte) (int, error) {
+	n := 0
+
+	for {
+		// Find next hash separator position
+		idx := bytes.IndexByte(b[n:], hashSeparator)
+		if idx == -1 {
+			// Check we shouldn't be expecting it
+			if w.buf.Len() > encodedHashLen {
+				return n, errInvalidNode
+			}
+
+			// Write all contents to buffer
+			w.buf.Write(b[n:])
+			return len(b), nil
+		}
+
+		// Found hash separator, write
+		// current buf contents to Node hashes
+		w.buf.Write(b[n : n+idx])
+		n += idx + 1
+		if w.buf.Len() != encodedHashLen {
+			return n, errInvalidNode
+		}
+
+		// Append to hashes & reset
+		w.node.hashes = append(w.node.hashes, w.buf.String())
+		w.buf.Reset()
+	}
+}
+
+// blockReader is an io.Reader implementation for the combined, linked block
+// data contained with a node file. Basically, this allows reading value data
+// from the store for a given node file
+type blockReader struct {
+	storage *BlockStorage
+	node    *node
+	buf     []byte
+	prev    int
+}
+
+func (r *blockReader) Read(b []byte) (int, error) {
+	n := 0
+
+	// Data left in buf, copy as much as we
+	// can into supplied read buffer
+	if r.prev < len(r.buf)-1 {
+		n += copy(b, r.buf[r.prev:])
+		r.prev += n
+		if n >= len(b) {
+			return n, nil
+		}
+	}
+
+	for {
+		// Check we have any hashes left
+		if len(r.node.hashes) < 1 {
+			return n, io.EOF
+		}
+
+		// Get next key from slice
+		key := r.node.hashes[0]
+		r.node.hashes = r.node.hashes[1:]
+
+		// Attempt to fetch next batch of data
+		var err error
+		r.buf, err = r.storage.readBlock(key)
+		if err != nil {
+			return n, err
+		}
+		r.prev = 0
+
+		// Copy as much as can from new buffer
+		m := copy(b[n:], r.buf)
+		r.prev += m
+		n += m
+
+		// If we hit end of supplied buf, return
+		if n >= len(b) {
+			return n, nil
+		}
+	}
+}
+
+// hashEncoder is a HashEncoder with built-in encode buffer
+type hashEncoder struct {
+	henc hashenc.HashEncoder
+	ebuf []byte
+}
+
+// encodedHashLen is the once-calculated encoded hash-sum length
+var encodedHashLen = hashenc.Base64().EncodedLen(
+	sha256.New().Size(),
+)
+
+// newHashEncoder returns a new hashEncoder instance
+func newHashEncoder() *hashEncoder {
+	hash := sha256.New()
+	enc := hashenc.Base64()
+	return &hashEncoder{
+		henc: hashenc.New(hash, enc),
+		ebuf: make([]byte, enc.EncodedLen(hash.Size())),
+	}
+}
+
+// EncodeSum encodes the src data and returns resulting bytes, only valid until next call to EncodeSum()
+func (henc *hashEncoder) EncodeSum(src []byte) bytes.Bytes {
+	henc.henc.EncodeSum(henc.ebuf, src)
+	return bytes.ToBytes(henc.ebuf)
+}

vendor/git.iim.gay/grufwub/go-store/storage/compressor.go

@@ -0,0 +1,104 @@
+package storage
+
+import (
+	"compress/gzip"
+	"compress/zlib"
+	"io"
+
+	"git.iim.gay/grufwub/go-store/util"
+	"github.com/golang/snappy"
+)
+
+// Compressor defines a means of compressing/decompressing values going into a key-value store
+type Compressor interface {
+	// Reader returns a new decompressing io.ReadCloser based on supplied (compressed) io.Reader
+	Reader(io.Reader) (io.ReadCloser, error)
+
+	// Writer returns a new compressing io.WriteCloser based on supplied (uncompressed) io.Writer
+	Writer(io.Writer) (io.WriteCloser, error)
+}
+
+type gzipCompressor struct {
+	level int
+}
+
+// GZipCompressor returns a new Compressor that implements GZip at default compression level
+func GZipCompressor() Compressor {
+	return GZipCompressorLevel(gzip.DefaultCompression)
+}
+
+// GZipCompressorLevel returns a new Compressor that implements GZip at supplied compression level
+func GZipCompressorLevel(level int) Compressor {
+	return &gzipCompressor{
+		level: level,
+	}
+}
+
+func (c *gzipCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
+	return gzip.NewReader(r)
+}
+
+func (c *gzipCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
+	return gzip.NewWriterLevel(w, c.level)
+}
+
+type zlibCompressor struct {
+	level int
+	dict  []byte
+}
+
+// ZLibCompressor returns a new Compressor that implements ZLib at default compression level
+func ZLibCompressor() Compressor {
+	return ZLibCompressorLevelDict(zlib.DefaultCompression, nil)
+}
+
+// ZLibCompressorLevel returns a new Compressor that implements ZLib at supplied compression level
+func ZLibCompressorLevel(level int) Compressor {
+	return ZLibCompressorLevelDict(level, nil)
+}
+
+// ZLibCompressorLevelDict returns a new Compressor that implements ZLib at supplied compression level with supplied dict
+func ZLibCompressorLevelDict(level int, dict []byte) Compressor {
+	return &zlibCompressor{
+		level: level,
+		dict:  dict,
+	}
+}
+
+func (c *zlibCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
+	return zlib.NewReaderDict(r, c.dict)
+}
+
+func (c *zlibCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
+	return zlib.NewWriterLevelDict(w, c.level, c.dict)
+}
+
+type snappyCompressor struct{}
+
+// SnappyCompressor returns a new Compressor that implements Snappy
+func SnappyCompressor() Compressor {
+	return &snappyCompressor{}
+}
+
+func (c *snappyCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
+	return util.NopReadCloser(snappy.NewReader(r)), nil
+}
+
+func (c *snappyCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
+	return snappy.NewBufferedWriter(w), nil
+}
+
+type nopCompressor struct{}
+
+// NoCompression is a Compressor that simply does nothing
+func NoCompression() Compressor {
+	return &nopCompressor{}
+}
+
+func (c *nopCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
+	return util.NopReadCloser(r), nil
+}
+
+func (c *nopCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
+	return util.NopWriteCloser(w), nil
+}

vendor/git.iim.gay/grufwub/go-store/storage/disk.go

@@ -0,0 +1,289 @@
+package storage
+
+import (
+	"io"
+	"io/fs"
+	"os"
+	"path"
+	"syscall"
+
+	"git.iim.gay/grufwub/fastpath"
+	"git.iim.gay/grufwub/go-bytes"
+	"git.iim.gay/grufwub/go-store/util"
+)
+
+// DefaultDiskConfig is the default DiskStorage configuration
+var DefaultDiskConfig = &DiskConfig{
+	Overwrite:    true,
+	WriteBufSize: 4096,
+	Transform:    NopTransform(),
+	Compression:  NoCompression(),
+}
+
+// DiskConfig defines options to be used when opening a DiskStorage
+type DiskConfig struct {
+	// Transform is the supplied key<-->path KeyTransform
+	Transform KeyTransform
+
+	// WriteBufSize is the buffer size to use when writing file streams (PutStream)
+	WriteBufSize int
+
+	// Overwrite allows overwriting values of stored keys in the storage
+	Overwrite bool
+
+	// Compression is the Compressor to use when reading / writing files, default is no compression
+	Compression Compressor
+}
+
+// getDiskConfig returns a valid DiskConfig for supplied ptr
+func getDiskConfig(cfg *DiskConfig) DiskConfig {
+	// If nil, use default
+	if cfg == nil {
+		cfg = DefaultDiskConfig
+	}
+
+	// Assume nil transform == none
+	if cfg.Transform == nil {
+		cfg.Transform = NopTransform()
+	}
+
+	// Assume nil compress == none
+	if cfg.Compression == nil {
+		cfg.Compression = NoCompression()
+	}
+
+	// Assume 0 buf size == use default
+	if cfg.WriteBufSize < 1 {
+		cfg.WriteBufSize = DefaultDiskConfig.WriteBufSize
+	}
+
+	// Return owned config copy
+	return DiskConfig{
+		Transform:    cfg.Transform,
+		WriteBufSize: cfg.WriteBufSize,
+		Overwrite:    cfg.Overwrite,
+		Compression:  cfg.Compression,
+	}
+}
+
+// DiskStorage is a Storage implementation that stores directly to a filesystem
+type DiskStorage struct {
+	path   string     // path is the root path of this store
+	dots   int        // dots is the "dotdot" count for the root store path
+	config DiskConfig // cfg is the supplied configuration for this store
+}
+
+// OpenFile opens a DiskStorage instance for given folder path and configuration
+func OpenFile(path string, cfg *DiskConfig) (*DiskStorage, error) {
+	// Acquire path builder
+	pb := util.AcquirePathBuilder()
+	defer util.ReleasePathBuilder(pb)
+
+	// Clean provided path, ensure ends in '/' (should
+	// be dir, this helps with file path trimming later)
+	path = pb.Clean(path) + "/"
+
+	// Get checked config
+	config := getDiskConfig(cfg)
+
+	// Attempt to open dir path
+	file, err := os.OpenFile(path, defaultFileROFlags, defaultDirPerms)
+	if err != nil {
+		// If not a not-exist error, return
+		if !os.IsNotExist(err) {
+			return nil, err
+		}
+
+		// Attempt to make store path dirs
+		err = os.MkdirAll(path, defaultDirPerms)
+		if err != nil {
+			return nil, err
+		}
+
+		// Reopen dir now it's been created
+		file, err = os.OpenFile(path, defaultFileROFlags, defaultDirPerms)
+		if err != nil {
+			return nil, err
+		}
+	}
+	defer file.Close()
+
+	// Double check this is a dir (NOT a file!)
+	stat, err := file.Stat()
+	if err != nil {
+		return nil, err
+	} else if !stat.IsDir() {
+		return nil, errPathIsFile
+	}
+
+	// Return new DiskStorage
+	return &DiskStorage{
+		path:   path,
+		dots:   util.CountDotdots(path),
+		config: config,
+	}, nil
+}
+
+// Clean implements Storage.Clean()
+func (st *DiskStorage) Clean() error {
+	return util.CleanDirs(st.path)
+}
+
+// ReadBytes implements Storage.ReadBytes()
+func (st *DiskStorage) ReadBytes(key string) ([]byte, error) {
+	// Get stream reader for key
+	rc, err := st.ReadStream(key)
+	if err != nil {
+		return nil, err
+	}
+	defer rc.Close()
+
+	// Read all bytes and return
+	return io.ReadAll(rc)
+}
+
+// ReadStream implements Storage.ReadStream()
+func (st *DiskStorage) ReadStream(key string) (io.ReadCloser, error) {
+	// Get file path for key
+	kpath, err := st.filepath(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// Attempt to open file (replace ENOENT with our own)
+	file, err := open(kpath, defaultFileROFlags)
+	if err != nil {
+		return nil, errSwapNotFound(err)
+	}
+
+	// Wrap the file in a compressor
+	cFile, err := st.config.Compression.Reader(file)
+	if err != nil {
+		file.Close() // close this here, ignore error
+		return nil, err
+	}
+
+	// Wrap compressor to ensure file close
+	return util.ReadCloserWithCallback(cFile, func() {
+		file.Close()
+	}), nil
+}
+
+// WriteBytes implements Storage.WriteBytes()
+func (st *DiskStorage) WriteBytes(key string, value []byte) error {
+	return st.WriteStream(key, bytes.NewReader(value))
+}
+
+// WriteStream implements Storage.WriteStream()
+func (st *DiskStorage) WriteStream(key string, r io.Reader) error {
+	// Get file path for key
+	kpath, err := st.filepath(key)
+	if err != nil {
+		return err
+	}
+
+	// Ensure dirs leading up to file exist
+	err = os.MkdirAll(path.Dir(kpath), defaultDirPerms)
+	if err != nil {
+		return err
+	}
+
+	// Prepare to swap error if need-be
+	errSwap := errSwapNoop
+
+	// Build file RW flags
+	flags := defaultFileRWFlags
+	if !st.config.Overwrite {
+		flags |= syscall.O_EXCL
+
+		// Catch + replace err exist
+		errSwap = errSwapExist
+	}
+
+	// Attempt to open file
+	file, err := open(kpath, flags)
+	if err != nil {
+		return errSwap(err)
+	}
+	defer file.Close()
+
+	// Wrap the file in a compressor
+	cFile, err := st.config.Compression.Writer(file)
+	if err != nil {
+		return err
+	}
+	defer cFile.Close()
+
+	// Acquire write buffer
+	buf := util.AcquireBuffer(st.config.WriteBufSize)
+	defer util.ReleaseBuffer(buf)
+	buf.Grow(st.config.WriteBufSize)
+
+	// Copy reader to file
+	_, err = io.CopyBuffer(cFile, r, buf.B)
+	return err
+}
+
+// Stat implements Storage.Stat()
+func (st *DiskStorage) Stat(key string) (bool, error) {
+	// Get file path for key
+	kpath, err := st.filepath(key)
+	if err != nil {
+		return false, err
+	}
+
+	// Check for file on disk
+	return stat(kpath)
+}
+
+// Remove implements Storage.Remove()
+func (st *DiskStorage) Remove(key string) error {
+	// Get file path for key
+	kpath, err := st.filepath(key)
+	if err != nil {
+		return err
+	}
+
+	// Attempt to remove file
+	return os.Remove(kpath)
+}
+
+// WalkKeys implements Storage.WalkKeys()
+func (st *DiskStorage) WalkKeys(opts *WalkKeysOptions) error {
+	// Acquire path builder
+	pb := fastpath.AcquireBuilder()
+	defer fastpath.ReleaseBuilder(pb)
+
+	// Walk dir for entries
+	return util.WalkDir(pb, st.path, func(kpath string, fsentry fs.DirEntry) {
+		// Only deal with regular files
+		if fsentry.Type().IsRegular() {
+			// Get full item path (without root)
+			kpath = pb.Join(kpath, fsentry.Name())[len(st.path):]
+
+			// Perform provided walk function
+			opts.WalkFn(entry(st.config.Transform.PathToKey(kpath)))
+		}
+	})
+}
+
+// filepath checks and returns a formatted filepath for given key
+func (st *DiskStorage) filepath(key string) (string, error) {
+	// Acquire path builder
+	pb := util.AcquirePathBuilder()
+	defer util.ReleasePathBuilder(pb)
+
+	// Calculate transformed key path
+	key = st.config.Transform.KeyToPath(key)
+
+	// Generated joined root path
+	pb.AppendString(st.path)
+	pb.AppendString(key)
+
+	// If path is dir traversal, and traverses FURTHER
+	// than store root, this is an error
+	if util.CountDotdots(pb.StringPtr()) > st.dots {
+		return "", ErrInvalidKey
+	}
+	return pb.String(), nil
+}

vendor/git.iim.gay/grufwub/go-store/storage/errors.go

@@ -0,0 +1,63 @@
+package storage
+
+import (
+	"fmt"
+	"syscall"
+)
+
+// errorString is our own simple error type
+type errorString string
+
+// Error implements error
+func (e errorString) Error() string {
+	return string(e)
+}
+
+// Extend appends extra information to an errorString
+func (e errorString) Extend(s string, a ...interface{}) errorString {
+	return errorString(string(e) + ": " + fmt.Sprintf(s, a...))
+}
+
+var (
+	// ErrNotFound is the error returned when a key cannot be found in storage
+	ErrNotFound = errorString("store/storage: key not found")
+
+	// ErrAlreadyExist is the error returned when a key already exists in storage
+	ErrAlreadyExists = errorString("store/storage: key already exists")
+
+	// ErrInvalidkey is the error returned when an invalid key is passed to storage
+	ErrInvalidKey = errorString("store/storage: invalid key")
+
+	// errPathIsFile is returned when a path for a disk config is actually a file
+	errPathIsFile = errorString("store/storage: path is file")
+
+	// errNoHashesWritten is returned when no blocks are written for given input value
+	errNoHashesWritten = errorString("storage/storage: no hashes written")
+
+	// errInvalidNode is returned when read on an invalid node in the store is attempted
+	errInvalidNode = errorString("store/storage: invalid node")
+
+	// errCorruptNodes is returned when nodes with missing blocks are found during a BlockStorage clean
+	errCorruptNodes = errorString("store/storage: corrupted nodes")
+)
+
+// errSwapNoop performs no error swaps
+func errSwapNoop(err error) error {
+	return err
+}
+
+// ErrSwapNotFound swaps syscall.ENOENT for ErrNotFound
+func errSwapNotFound(err error) error {
+	if err == syscall.ENOENT {
+		return ErrNotFound
+	}
+	return err
+}
+
+// errSwapExist swaps syscall.EEXIST for ErrAlreadyExists
+func errSwapExist(err error) error {
+	if err == syscall.EEXIST {
+		return ErrAlreadyExists
+	}
+	return err
+}

vendor/git.iim.gay/grufwub/go-store/storage/fs.go

@@ -0,0 +1,48 @@
+package storage
+
+import (
+	"os"
+	"syscall"
+
+	"git.iim.gay/grufwub/go-store/util"
+)
+
+const (
+	defaultDirPerms      = 0755
+	defaultFilePerms     = 0644
+	defaultFileROFlags   = syscall.O_RDONLY
+	defaultFileRWFlags   = syscall.O_CREAT | syscall.O_RDWR
+	defaultFileLockFlags = syscall.O_RDONLY | syscall.O_EXCL | syscall.O_CREAT
+)
+
+// NOTE:
+// These functions are for opening storage files,
+// not necessarily for e.g. initial setup (OpenFile)
+
+// open should not be called directly
+func open(path string, flags int) (*os.File, error) {
+	var fd int
+	err := util.RetryOnEINTR(func() (err error) {
+		fd, err = syscall.Open(path, flags, defaultFilePerms)
+		return
+	})
+	if err != nil {
+		return nil, err
+	}
+	return os.NewFile(uintptr(fd), path), nil
+}
+
+// stat checks for a file on disk
+func stat(path string) (bool, error) {
+	var stat syscall.Stat_t
+	err := util.RetryOnEINTR(func() error {
+		return syscall.Stat(path, &stat)
+	})
+	if err != nil {
+		if err == syscall.ENOENT {
+			err = nil
+		}
+		return false, err
+	}
+	return true, nil
+}

vendor/git.iim.gay/grufwub/go-store/storage/lock.go

@@ -0,0 +1,34 @@
+package storage
+
+import (
+	"os"
+	"syscall"
+
+	"git.iim.gay/grufwub/go-store/util"
+)
+
+type lockableFile struct {
+	*os.File
+}
+
+func openLock(path string) (*lockableFile, error) {
+	file, err := open(path, defaultFileLockFlags)
+	if err != nil {
+		return nil, err
+	}
+	return &lockableFile{file}, nil
+}
+
+func (f *lockableFile) lock() error {
+	return f.flock(syscall.LOCK_EX | syscall.LOCK_NB)
+}
+
+func (f *lockableFile) unlock() error {
+	return f.flock(syscall.LOCK_UN | syscall.LOCK_NB)
+}
+
+func (f *lockableFile) flock(how int) error {
+	return util.RetryOnEINTR(func() error {
+		return syscall.Flock(int(f.Fd()), how)
+	})
+}

vendor/git.iim.gay/grufwub/go-store/storage/storage.go

@@ -0,0 +1,51 @@
+package storage
+
+import (
+	"io"
+)
+
+// StorageEntry defines a key in Storage
+type StorageEntry interface {
+	// Key returns the storage entry's key
+	Key() string
+}
+
+// entry is the simplest possible StorageEntry
+type entry string
+
+func (e entry) Key() string {
+	return string(e)
+}
+
+// Storage defines a means of storing and accessing key value pairs
+type Storage interface {
+	// Clean removes unused values and unclutters the storage (e.g. removing empty folders)
+	Clean() error
+
+	// ReadBytes returns the byte value for key in storage
+	ReadBytes(key string) ([]byte, error)
+
+	// ReadStream returns an io.ReadCloser for the value bytes at key in the storage
+	ReadStream(key string) (io.ReadCloser, error)
+
+	// WriteBytes writes the supplied value bytes at key in the storage
+	WriteBytes(key string, value []byte) error
+
+	// WriteStream writes the bytes from supplied reader at key in the storage
+	WriteStream(key string, r io.Reader) error
+
+	// Stat checks if the supplied key is in the storage
+	Stat(key string) (bool, error)
+
+	// Remove attempts to remove the supplied key-value pair from storage
+	Remove(key string) error
+
+	// WalkKeys walks the keys in the storage
+	WalkKeys(opts *WalkKeysOptions) error
+}
+
+// WalkKeysOptions defines how to walk the keys in a storage implementation
+type WalkKeysOptions struct {
+	// WalkFn is the function to apply on each StorageEntry
+	WalkFn func(StorageEntry)
+}

vendor/git.iim.gay/grufwub/go-store/storage/transform.go

@@ -0,0 +1,25 @@
+package storage
+
+// KeyTransform defines a method of converting store keys to storage paths (and vice-versa)
+type KeyTransform interface {
+	// KeyToPath converts a supplied key to storage path
+	KeyToPath(string) string
+
+	// PathToKey converts a supplied storage path to key
+	PathToKey(string) string
+}
+
+type nopKeyTransform struct{}
+
+// NopTransform returns a nop key transform (i.e. key = path)
+func NopTransform() KeyTransform {
+	return &nopKeyTransform{}
+}
+
+func (t *nopKeyTransform) KeyToPath(key string) string {
+	return key
+}
+
+func (t *nopKeyTransform) PathToKey(path string) string {
+	return path
+}

vendor/git.iim.gay/grufwub/go-store/util/fs.go

@@ -0,0 +1,105 @@
+package util
+
+import (
+	"io/fs"
+	"os"
+	"strings"
+	"syscall"
+
+	"git.iim.gay/grufwub/fastpath"
+)
+
+var dotdot = "../"
+
+// CountDotdots returns the number of "dot-dots" (../) in a cleaned filesystem path
+func CountDotdots(path string) int {
+	if !strings.HasSuffix(path, dotdot) {
+		return 0
+	}
+	return strings.Count(path, dotdot)
+}
+
+// WalkDir traverses the dir tree of the supplied path, performing the supplied walkFn on each entry
+func WalkDir(pb *fastpath.Builder, path string, walkFn func(string, fs.DirEntry)) error {
+	// Read supplied dir path
+	dirEntries, err := os.ReadDir(path)
+	if err != nil {
+		return err
+	}
+
+	// Iter entries
+	for _, entry := range dirEntries {
+		// Pass to walk fn
+		walkFn(path, entry)
+
+		// Recurse dir entries
+		if entry.IsDir() {
+			err = WalkDir(pb, pb.Join(path, entry.Name()), walkFn)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// CleanDirs traverses the dir tree of the supplied path, removing any folders with zero children
+func CleanDirs(path string) error {
+	// Acquire builder
+	pb := AcquirePathBuilder()
+	defer ReleasePathBuilder(pb)
+
+	// Get dir entries
+	entries, err := os.ReadDir(path)
+	if err != nil {
+		return err
+	}
+
+	// Recurse dirs
+	for _, entry := range entries {
+		if entry.IsDir() {
+			err := cleanDirs(pb, pb.Join(path, entry.Name()))
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// cleanDirs performs the actual dir cleaning logic for the exported version
+func cleanDirs(pb *fastpath.Builder, path string) error {
+	// Get dir entries
+	entries, err := os.ReadDir(path)
+	if err != nil {
+		return err
+	}
+
+	// If no entries, delete
+	if len(entries) < 1 {
+		return os.Remove(path)
+	}
+
+	// Recurse dirs
+	for _, entry := range entries {
+		if entry.IsDir() {
+			err := cleanDirs(pb, pb.Join(path, entry.Name()))
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// RetryOnEINTR is a low-level filesystem function for retrying syscalls on O_EINTR received
+func RetryOnEINTR(do func() error) error {
+	for {
+		err := do()
+		if err == syscall.EINTR {
+			continue
+		}
+		return err
+	}
+}

vendor/git.iim.gay/grufwub/go-store/util/io.go

@@ -0,0 +1,42 @@
+package util
+
+import "io"
+
+// NopReadCloser turns a supplied io.Reader into io.ReadCloser with a nop Close() implementation
+func NopReadCloser(r io.Reader) io.ReadCloser {
+	return &nopReadCloser{r}
+}
+
+// NopWriteCloser turns a supplied io.Writer into io.WriteCloser with a nop Close() implementation
+func NopWriteCloser(w io.Writer) io.WriteCloser {
+	return &nopWriteCloser{w}
+}
+
+// ReadCloserWithCallback adds a customizable callback to be called upon Close() of a supplied io.ReadCloser
+func ReadCloserWithCallback(rc io.ReadCloser, cb func()) io.ReadCloser {
+	return &callbackReadCloser{
+		ReadCloser: rc,
+		callback:   cb,
+	}
+}
+
+// nopReadCloser turns an io.Reader -> io.ReadCloser with a nop Close()
+type nopReadCloser struct{ io.Reader }
+
+func (r *nopReadCloser) Close() error { return nil }
+
+// nopWriteCloser turns an io.Writer -> io.WriteCloser with a nop Close()
+type nopWriteCloser struct{ io.Writer }
+
+func (w nopWriteCloser) Close() error { return nil }
+
+// callbackReadCloser allows adding our own custom callback to an io.ReadCloser
+type callbackReadCloser struct {
+	io.ReadCloser
+	callback func()
+}
+
+func (c *callbackReadCloser) Close() error {
+	defer c.callback()
+	return c.ReadCloser.Close()
+}

vendor/git.iim.gay/grufwub/go-store/util/nocopy.go

@@ -0,0 +1,6 @@
+package util
+
+type NoCopy struct{}
+
+func (*NoCopy) Lock()   {}
+func (*NoCopy) Unlock() {}

vendor/git.iim.gay/grufwub/go-store/util/pools.go

@@ -0,0 +1,44 @@
+package util
+
+import (
+	"sync"
+
+	"git.iim.gay/grufwub/fastpath"
+	"git.iim.gay/grufwub/go-bufpool"
+	"git.iim.gay/grufwub/go-bytes"
+)
+
+// pathBuilderPool is the global fastpath.Builder pool, we implement
+// our own here instead of using fastpath's default one because we
+// don't want to deal with fastpath's sync.Once locks on every Acquire/Release
+var pathBuilderPool = sync.Pool{
+	New: func() interface{} {
+		pb := fastpath.NewBuilder(make([]byte, 0, 512))
+		return &pb
+	},
+}
+
+// AcquirePathBuilder returns a reset fastpath.Builder instance
+func AcquirePathBuilder() *fastpath.Builder {
+	return pathBuilderPool.Get().(*fastpath.Builder)
+}
+
+// ReleasePathBuilder resets and releases provided fastpath.Builder instance to global pool
+func ReleasePathBuilder(pb *fastpath.Builder) {
+	pb.Reset()
+	pathBuilderPool.Put(pb)
+}
+
+// bufferPool is the global BufferPool, we implement this here
+// so we can share allocations across whatever libaries need them.
+var bufferPool = bufpool.BufferPool{}
+
+// AcquireBuffer returns a reset bytes.Buffer with at least requested capacity
+func AcquireBuffer(cap int) *bytes.Buffer {
+	return bufferPool.Get(cap)
+}
+
+// ReleaseBuffer resets and releases provided bytes.Buffer to global BufferPool
+func ReleaseBuffer(buf *bytes.Buffer) {
+	bufferPool.Put(buf)
+}