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254 lines
5.0 KiB
254 lines
5.0 KiB
package db
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import (
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"fmt"
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"io/ioutil"
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"net/url"
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"os"
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"path/filepath"
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"sort"
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"sync"
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"github.com/pkg/errors"
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cmn "github.com/tendermint/tmlibs/common"
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)
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const (
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keyPerm = os.FileMode(0600)
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dirPerm = os.FileMode(0700)
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)
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func init() {
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registerDBCreator(FSDBBackendStr, func(name string, dir string) (DB, error) {
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dbPath := filepath.Join(dir, name+".db")
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return NewFSDB(dbPath), nil
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}, false)
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}
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var _ DB = (*FSDB)(nil)
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// It's slow.
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type FSDB struct {
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mtx sync.Mutex
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dir string
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}
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func NewFSDB(dir string) *FSDB {
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err := os.MkdirAll(dir, dirPerm)
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if err != nil {
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panic(errors.Wrap(err, "Creating FSDB dir "+dir))
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}
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database := &FSDB{
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dir: dir,
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}
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return database
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}
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func (db *FSDB) Get(key []byte) []byte {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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key = escapeKey(key)
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path := db.nameToPath(key)
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value, err := read(path)
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if os.IsNotExist(err) {
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return nil
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} else if err != nil {
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panic(errors.Wrapf(err, "Getting key %s (0x%X)", string(key), key))
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}
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return value
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}
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func (db *FSDB) Has(key []byte) bool {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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key = escapeKey(key)
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path := db.nameToPath(key)
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return cmn.FileExists(path)
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}
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func (db *FSDB) Set(key []byte, value []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.SetNoLock(key, value)
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}
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func (db *FSDB) SetSync(key []byte, value []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.SetNoLock(key, value)
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}
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// NOTE: Implements atomicSetDeleter.
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func (db *FSDB) SetNoLock(key []byte, value []byte) {
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key = escapeKey(key)
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value = nonNilBytes(value)
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path := db.nameToPath(key)
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err := write(path, value)
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if err != nil {
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panic(errors.Wrapf(err, "Setting key %s (0x%X)", string(key), key))
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}
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}
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func (db *FSDB) Delete(key []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.DeleteNoLock(key)
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}
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func (db *FSDB) DeleteSync(key []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.DeleteNoLock(key)
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}
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// NOTE: Implements atomicSetDeleter.
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func (db *FSDB) DeleteNoLock(key []byte) {
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key = escapeKey(key)
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path := db.nameToPath(key)
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err := remove(path)
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if os.IsNotExist(err) {
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return
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} else if err != nil {
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panic(errors.Wrapf(err, "Removing key %s (0x%X)", string(key), key))
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}
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}
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func (db *FSDB) Close() {
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// Nothing to do.
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}
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func (db *FSDB) Print() {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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panic("FSDB.Print not yet implemented")
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}
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func (db *FSDB) Stats() map[string]string {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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panic("FSDB.Stats not yet implemented")
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}
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func (db *FSDB) NewBatch() Batch {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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// Not sure we would ever want to try...
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// It doesn't seem easy for general filesystems.
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panic("FSDB.NewBatch not yet implemented")
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}
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func (db *FSDB) Mutex() *sync.Mutex {
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return &(db.mtx)
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}
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func (db *FSDB) Iterator(start, end []byte) Iterator {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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// We need a copy of all of the keys.
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// Not the best, but probably not a bottleneck depending.
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keys, err := list(db.dir, start, end)
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if err != nil {
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panic(errors.Wrapf(err, "Listing keys in %s", db.dir))
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}
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sort.Strings(keys)
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return newMemDBIterator(db, keys, start, end)
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}
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func (db *FSDB) ReverseIterator(start, end []byte) Iterator {
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panic("not implemented yet") // XXX
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}
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func (db *FSDB) nameToPath(name []byte) string {
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n := url.PathEscape(string(name))
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return filepath.Join(db.dir, n)
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}
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// Read some bytes to a file.
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// CONTRACT: returns os errors directly without wrapping.
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func read(path string) ([]byte, error) {
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f, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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d, err := ioutil.ReadAll(f)
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if err != nil {
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return nil, err
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}
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return d, nil
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}
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// Write some bytes from a file.
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// CONTRACT: returns os errors directly without wrapping.
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func write(path string, d []byte) error {
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f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, keyPerm)
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if err != nil {
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return err
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}
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defer f.Close()
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_, err = f.Write(d)
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if err != nil {
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return err
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}
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err = f.Sync()
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return err
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}
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// Remove a file.
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// CONTRACT: returns os errors directly without wrapping.
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func remove(path string) error {
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return os.Remove(path)
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}
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// List keys in a directory, stripping of escape sequences and dir portions.
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// CONTRACT: returns os errors directly without wrapping.
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func list(dirPath string, start, end []byte) ([]string, error) {
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dir, err := os.Open(dirPath)
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if err != nil {
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return nil, err
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}
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defer dir.Close()
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names, err := dir.Readdirnames(0)
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if err != nil {
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return nil, err
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}
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var keys []string
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for _, name := range names {
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n, err := url.PathUnescape(name)
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if err != nil {
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return nil, fmt.Errorf("Failed to unescape %s while listing", name)
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}
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key := unescapeKey([]byte(n))
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if IsKeyInDomain(key, start, end, false) {
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keys = append(keys, string(key))
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}
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}
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return keys, nil
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}
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// To support empty or nil keys, while the file system doesn't allow empty
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// filenames.
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func escapeKey(key []byte) []byte {
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return []byte("k_" + string(key))
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}
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func unescapeKey(escKey []byte) []byte {
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if len(escKey) < 2 {
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panic(fmt.Sprintf("Invalid esc key: %x", escKey))
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}
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if string(escKey[:2]) != "k_" {
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panic(fmt.Sprintf("Invalid esc key: %x", escKey))
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}
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return escKey[2:]
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}
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