mirror of
https://github.com/restic/restic.git
synced 2024-08-30 08:07:23 +02:00
365 lines
8.9 KiB
Go
365 lines
8.9 KiB
Go
package local
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import (
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"context"
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"hash"
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"io"
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"os"
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"path/filepath"
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"syscall"
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"github.com/restic/restic/internal/backend"
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"github.com/restic/restic/internal/backend/layout"
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"github.com/restic/restic/internal/backend/limiter"
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"github.com/restic/restic/internal/backend/location"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/fs"
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"github.com/restic/restic/internal/restic"
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"github.com/cenkalti/backoff/v4"
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)
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// Local is a backend in a local directory.
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type Local struct {
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Config
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layout.Layout
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backend.Modes
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}
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// ensure statically that *Local implements restic.Backend.
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var _ restic.Backend = &Local{}
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func NewFactory() location.Factory {
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return location.NewLimitedBackendFactory(ParseConfig, location.NoPassword, limiter.WrapBackendConstructor(Create), limiter.WrapBackendConstructor(Open))
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}
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const defaultLayout = "default"
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func open(ctx context.Context, cfg Config) (*Local, error) {
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l, err := layout.ParseLayout(ctx, &layout.LocalFilesystem{}, cfg.Layout, defaultLayout, cfg.Path)
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if err != nil {
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return nil, err
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}
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fi, err := fs.Stat(l.Filename(restic.Handle{Type: restic.ConfigFile}))
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m := backend.DeriveModesFromFileInfo(fi, err)
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debug.Log("using (%03O file, %03O dir) permissions", m.File, m.Dir)
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return &Local{
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Config: cfg,
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Layout: l,
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Modes: m,
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}, nil
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}
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// Open opens the local backend as specified by config.
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func Open(ctx context.Context, cfg Config) (*Local, error) {
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debug.Log("open local backend at %v (layout %q)", cfg.Path, cfg.Layout)
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return open(ctx, cfg)
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}
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// Create creates all the necessary files and directories for a new local
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// backend at dir. Afterwards a new config blob should be created.
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func Create(ctx context.Context, cfg Config) (*Local, error) {
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debug.Log("create local backend at %v (layout %q)", cfg.Path, cfg.Layout)
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be, err := open(ctx, cfg)
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if err != nil {
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return nil, err
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}
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// test if config file already exists
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_, err = fs.Lstat(be.Filename(restic.Handle{Type: restic.ConfigFile}))
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if err == nil {
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return nil, errors.New("config file already exists")
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}
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// create paths for data and refs
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for _, d := range be.Paths() {
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err := fs.MkdirAll(d, be.Modes.Dir)
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if err != nil {
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return nil, errors.WithStack(err)
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}
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}
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return be, nil
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}
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func (b *Local) Connections() uint {
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return b.Config.Connections
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}
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// Location returns this backend's location (the directory name).
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func (b *Local) Location() string {
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return b.Path
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}
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// Hasher may return a hash function for calculating a content hash for the backend
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func (b *Local) Hasher() hash.Hash {
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return nil
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}
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// HasAtomicReplace returns whether Save() can atomically replace files
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func (b *Local) HasAtomicReplace() bool {
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return true
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}
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// IsNotExist returns true if the error is caused by a non existing file.
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func (b *Local) IsNotExist(err error) bool {
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return errors.Is(err, os.ErrNotExist)
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}
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// Save stores data in the backend at the handle.
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func (b *Local) Save(_ context.Context, h restic.Handle, rd restic.RewindReader) (err error) {
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finalname := b.Filename(h)
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dir := filepath.Dir(finalname)
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defer func() {
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// Mark non-retriable errors as such
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if errors.Is(err, syscall.ENOSPC) || os.IsPermission(err) {
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err = backoff.Permanent(err)
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}
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}()
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// Create new file with a temporary name.
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tmpname := filepath.Base(finalname) + "-tmp-"
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f, err := tempFile(dir, tmpname)
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if b.IsNotExist(err) {
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debug.Log("error %v: creating dir", err)
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// error is caused by a missing directory, try to create it
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mkdirErr := fs.MkdirAll(dir, b.Modes.Dir)
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if mkdirErr != nil {
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debug.Log("error creating dir %v: %v", dir, mkdirErr)
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} else {
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// try again
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f, err = tempFile(dir, tmpname)
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}
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}
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if err != nil {
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return errors.WithStack(err)
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}
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defer func(f *os.File) {
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if err != nil {
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_ = f.Close() // Double Close is harmless.
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// Remove after Rename is harmless: we embed the final name in the
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// temporary's name and no other goroutine will get the same data to
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// Save, so the temporary name should never be reused by another
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// goroutine.
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_ = fs.Remove(f.Name())
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}
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}(f)
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// preallocate disk space
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if size := rd.Length(); size > 0 {
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if err := fs.PreallocateFile(f, size); err != nil {
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debug.Log("Failed to preallocate %v with size %v: %v", finalname, size, err)
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}
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}
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// save data, then sync
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wbytes, err := io.Copy(f, rd)
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if err != nil {
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return errors.WithStack(err)
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}
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// sanity check
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if wbytes != rd.Length() {
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return errors.Errorf("wrote %d bytes instead of the expected %d bytes", wbytes, rd.Length())
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}
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// Ignore error if filesystem does not support fsync.
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err = f.Sync()
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syncNotSup := err != nil && (errors.Is(err, syscall.ENOTSUP) || isMacENOTTY(err))
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if err != nil && !syncNotSup {
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return errors.WithStack(err)
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}
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// Close, then rename. Windows doesn't like the reverse order.
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if err = f.Close(); err != nil {
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return errors.WithStack(err)
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}
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if err = os.Rename(f.Name(), finalname); err != nil {
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return errors.WithStack(err)
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}
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// Now sync the directory to commit the Rename.
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if !syncNotSup {
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err = fsyncDir(dir)
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if err != nil {
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return errors.WithStack(err)
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}
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}
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// try to mark file as read-only to avoid accidential modifications
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// ignore if the operation fails as some filesystems don't allow the chmod call
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// e.g. exfat and network file systems with certain mount options
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err = setFileReadonly(finalname, b.Modes.File)
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if err != nil && !os.IsPermission(err) {
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return errors.WithStack(err)
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}
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return nil
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}
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var tempFile = os.CreateTemp // Overridden by test.
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// Load runs fn with a reader that yields the contents of the file at h at the
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// given offset.
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func (b *Local) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
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return backend.DefaultLoad(ctx, h, length, offset, b.openReader, fn)
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}
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func (b *Local) openReader(_ context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
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f, err := fs.Open(b.Filename(h))
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if err != nil {
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return nil, err
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}
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if offset > 0 {
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_, err = f.Seek(offset, 0)
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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}
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if length > 0 {
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return backend.LimitReadCloser(f, int64(length)), nil
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}
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return f, nil
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}
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// Stat returns information about a blob.
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func (b *Local) Stat(_ context.Context, h restic.Handle) (restic.FileInfo, error) {
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fi, err := fs.Stat(b.Filename(h))
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if err != nil {
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return restic.FileInfo{}, errors.WithStack(err)
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}
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return restic.FileInfo{Size: fi.Size(), Name: h.Name}, nil
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}
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// Remove removes the blob with the given name and type.
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func (b *Local) Remove(_ context.Context, h restic.Handle) error {
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fn := b.Filename(h)
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// reset read-only flag
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err := fs.Chmod(fn, 0666)
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if err != nil && !os.IsPermission(err) {
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return errors.WithStack(err)
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}
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return fs.Remove(fn)
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}
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// List runs fn for each file in the backend which has the type t. When an
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// error occurs (or fn returns an error), List stops and returns it.
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func (b *Local) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) (err error) {
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basedir, subdirs := b.Basedir(t)
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if subdirs {
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err = visitDirs(ctx, basedir, fn)
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} else {
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err = visitFiles(ctx, basedir, fn, false)
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}
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if b.IsNotExist(err) {
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debug.Log("ignoring non-existing directory")
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return nil
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}
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return err
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}
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// The following two functions are like filepath.Walk, but visit only one or
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// two levels of directory structure (including dir itself as the first level).
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// Also, visitDirs assumes it sees a directory full of directories, while
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// visitFiles wants a directory full or regular files.
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func visitDirs(ctx context.Context, dir string, fn func(restic.FileInfo) error) error {
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d, err := fs.Open(dir)
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if err != nil {
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return err
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}
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sub, err := d.Readdirnames(-1)
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if err != nil {
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// ignore subsequent errors
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_ = d.Close()
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return err
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}
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err = d.Close()
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if err != nil {
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return err
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}
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for _, f := range sub {
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err = visitFiles(ctx, filepath.Join(dir, f), fn, true)
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if err != nil {
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return err
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}
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}
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return ctx.Err()
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}
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func visitFiles(ctx context.Context, dir string, fn func(restic.FileInfo) error, ignoreNotADirectory bool) error {
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d, err := fs.Open(dir)
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if err != nil {
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return err
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}
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if ignoreNotADirectory {
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fi, err := d.Stat()
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if err != nil || !fi.IsDir() {
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// ignore subsequent errors
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_ = d.Close()
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return err
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}
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}
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sub, err := d.Readdir(-1)
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if err != nil {
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// ignore subsequent errors
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_ = d.Close()
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return err
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}
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err = d.Close()
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if err != nil {
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return err
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}
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for _, fi := range sub {
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select {
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case <-ctx.Done():
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return ctx.Err()
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default:
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}
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err := fn(restic.FileInfo{
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Name: fi.Name(),
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Size: fi.Size(),
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})
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if err != nil {
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return err
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}
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}
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return nil
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}
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// Delete removes the repository and all files.
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func (b *Local) Delete(_ context.Context) error {
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return fs.RemoveAll(b.Path)
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}
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// Close closes all open files.
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func (b *Local) Close() error {
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// this does not need to do anything, all open files are closed within the
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// same function.
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return nil
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}
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