package repository import ( "bufio" "bytes" "context" "fmt" "io" "os" "runtime" "sort" "sync" "github.com/cenkalti/backoff/v4" "github.com/klauspost/compress/zstd" "github.com/restic/chunker" "github.com/restic/restic/internal/backend" "github.com/restic/restic/internal/backend/dryrun" "github.com/restic/restic/internal/cache" "github.com/restic/restic/internal/crypto" "github.com/restic/restic/internal/debug" "github.com/restic/restic/internal/errors" "github.com/restic/restic/internal/index" "github.com/restic/restic/internal/pack" "github.com/restic/restic/internal/restic" "github.com/restic/restic/internal/ui/progress" "golang.org/x/sync/errgroup" ) const MaxStreamBufferSize = 4 * 1024 * 1024 const MinPackSize = 4 * 1024 * 1024 const DefaultPackSize = 16 * 1024 * 1024 const MaxPackSize = 128 * 1024 * 1024 // Repository is used to access a repository in a backend. type Repository struct { be restic.Backend cfg restic.Config key *crypto.Key keyID restic.ID idx *index.MasterIndex Cache *cache.Cache opts Options noAutoIndexUpdate bool packerWg *errgroup.Group uploader *packerUploader treePM *packerManager dataPM *packerManager allocEnc sync.Once allocDec sync.Once enc *zstd.Encoder dec *zstd.Decoder } type Options struct { Compression CompressionMode PackSize uint } // CompressionMode configures if data should be compressed. type CompressionMode uint // Constants for the different compression levels. const ( CompressionAuto CompressionMode = 0 CompressionOff CompressionMode = 1 CompressionMax CompressionMode = 2 CompressionInvalid CompressionMode = 3 ) // Set implements the method needed for pflag command flag parsing. func (c *CompressionMode) Set(s string) error { switch s { case "auto": *c = CompressionAuto case "off": *c = CompressionOff case "max": *c = CompressionMax default: *c = CompressionInvalid return fmt.Errorf("invalid compression mode %q, must be one of (auto|off|max)", s) } return nil } func (c *CompressionMode) String() string { switch *c { case CompressionAuto: return "auto" case CompressionOff: return "off" case CompressionMax: return "max" default: return "invalid" } } func (c *CompressionMode) Type() string { return "mode" } // New returns a new repository with backend be. func New(be restic.Backend, opts Options) (*Repository, error) { if opts.Compression == CompressionInvalid { return nil, errors.New("invalid compression mode") } if opts.PackSize == 0 { opts.PackSize = DefaultPackSize } if opts.PackSize > MaxPackSize { return nil, fmt.Errorf("pack size larger than limit of %v MiB", MaxPackSize/1024/1024) } else if opts.PackSize < MinPackSize { return nil, fmt.Errorf("pack size smaller than minimum of %v MiB", MinPackSize/1024/1024) } repo := &Repository{ be: be, opts: opts, idx: index.NewMasterIndex(), } return repo, nil } // DisableAutoIndexUpdate deactives the automatic finalization and upload of new // indexes once these are full func (r *Repository) DisableAutoIndexUpdate() { r.noAutoIndexUpdate = true } // setConfig assigns the given config and updates the repository parameters accordingly func (r *Repository) setConfig(cfg restic.Config) { r.cfg = cfg if r.cfg.Version >= 2 { r.idx.MarkCompressed() } } // Config returns the repository configuration. func (r *Repository) Config() restic.Config { return r.cfg } // PackSize return the target size of a pack file when uploading func (r *Repository) PackSize() uint { return r.opts.PackSize } // UseCache replaces the backend with the wrapped cache. func (r *Repository) UseCache(c *cache.Cache) { if c == nil { return } debug.Log("using cache") r.Cache = c r.be = c.Wrap(r.be) } // SetDryRun sets the repo backend into dry-run mode. func (r *Repository) SetDryRun() { r.be = dryrun.New(r.be) } // LoadUnpacked loads and decrypts the file with the given type and ID. func (r *Repository) LoadUnpacked(ctx context.Context, t restic.FileType, id restic.ID) ([]byte, error) { debug.Log("load %v with id %v", t, id) if t == restic.ConfigFile { id = restic.ID{} } ctx, cancel := context.WithCancel(ctx) h := restic.Handle{Type: t, Name: id.String()} retriedInvalidData := false var dataErr error wr := new(bytes.Buffer) err := r.be.Load(ctx, h, 0, 0, func(rd io.Reader) error { // make sure this call is idempotent, in case an error occurs wr.Reset() _, cerr := io.Copy(wr, rd) if cerr != nil { return cerr } buf := wr.Bytes() if t != restic.ConfigFile && !restic.Hash(buf).Equal(id) { debug.Log("retry loading broken blob %v", h) if !retriedInvalidData { retriedInvalidData = true } else { // with a canceled context there is not guarantee which error will // be returned by `be.Load`. dataErr = fmt.Errorf("load(%v): %w", h, restic.ErrInvalidData) cancel() } return restic.ErrInvalidData } return nil }) if dataErr != nil { return nil, dataErr } if err != nil { return nil, err } buf := wr.Bytes() nonce, ciphertext := buf[:r.key.NonceSize()], buf[r.key.NonceSize():] plaintext, err := r.key.Open(ciphertext[:0], nonce, ciphertext, nil) if err != nil { return nil, err } if t != restic.ConfigFile { return r.decompressUnpacked(plaintext) } return plaintext, nil } type haver interface { Has(restic.Handle) bool } // sortCachedPacksFirst moves all cached pack files to the front of blobs. func sortCachedPacksFirst(cache haver, blobs []restic.PackedBlob) { if cache == nil { return } // no need to sort a list with one element if len(blobs) == 1 { return } cached := blobs[:0] noncached := make([]restic.PackedBlob, 0, len(blobs)/2) for _, blob := range blobs { if cache.Has(restic.Handle{Type: restic.PackFile, Name: blob.PackID.String()}) { cached = append(cached, blob) continue } noncached = append(noncached, blob) } copy(blobs[len(cached):], noncached) } // LoadBlob loads a blob of type t from the repository. // It may use all of buf[:cap(buf)] as scratch space. func (r *Repository) LoadBlob(ctx context.Context, t restic.BlobType, id restic.ID, buf []byte) ([]byte, error) { debug.Log("load %v with id %v (buf len %v, cap %d)", t, id, len(buf), cap(buf)) // lookup packs blobs := r.idx.Lookup(restic.BlobHandle{ID: id, Type: t}) if len(blobs) == 0 { debug.Log("id %v not found in index", id) return nil, errors.Errorf("id %v not found in repository", id) } // try cached pack files first sortCachedPacksFirst(r.Cache, blobs) var lastError error for _, blob := range blobs { debug.Log("blob %v/%v found: %v", t, id, blob) if blob.Type != t { debug.Log("blob %v has wrong block type, want %v", blob, t) } // load blob from pack h := restic.Handle{Type: restic.PackFile, Name: blob.PackID.String(), IsMetadata: t.IsMetadata()} switch { case cap(buf) < int(blob.Length): buf = make([]byte, blob.Length) case len(buf) != int(blob.Length): buf = buf[:blob.Length] } n, err := backend.ReadAt(ctx, r.be, h, int64(blob.Offset), buf) if err != nil { debug.Log("error loading blob %v: %v", blob, err) lastError = err continue } if uint(n) != blob.Length { lastError = errors.Errorf("error loading blob %v: wrong length returned, want %d, got %d", id.Str(), blob.Length, uint(n)) debug.Log("lastError: %v", lastError) continue } // decrypt nonce, ciphertext := buf[:r.key.NonceSize()], buf[r.key.NonceSize():] plaintext, err := r.key.Open(ciphertext[:0], nonce, ciphertext, nil) if err != nil { lastError = errors.Errorf("decrypting blob %v failed: %v", id, err) continue } if blob.IsCompressed() { plaintext, err = r.getZstdDecoder().DecodeAll(plaintext, make([]byte, 0, blob.DataLength())) if err != nil { lastError = errors.Errorf("decompressing blob %v failed: %v", id, err) continue } } // check hash if !restic.Hash(plaintext).Equal(id) { lastError = errors.Errorf("blob %v returned invalid hash", id) continue } if len(plaintext) > cap(buf) { return plaintext, nil } // move decrypted data to the start of the buffer buf = buf[:len(plaintext)] copy(buf, plaintext) return buf, nil } if lastError != nil { return nil, lastError } return nil, errors.Errorf("loading blob %v from %v packs failed", id.Str(), len(blobs)) } // LookupBlobSize returns the size of blob id. func (r *Repository) LookupBlobSize(id restic.ID, tpe restic.BlobType) (uint, bool) { return r.idx.LookupSize(restic.BlobHandle{ID: id, Type: tpe}) } func (r *Repository) getZstdEncoder() *zstd.Encoder { r.allocEnc.Do(func() { level := zstd.SpeedDefault if r.opts.Compression == CompressionMax { level = zstd.SpeedBestCompression } opts := []zstd.EOption{ // Set the compression level configured. zstd.WithEncoderLevel(level), // Disable CRC, we have enough checks in place, makes the // compressed data four bytes shorter. zstd.WithEncoderCRC(false), // Set a window of 512kbyte, so we have good lookbehind for usual // blob sizes. zstd.WithWindowSize(512 * 1024), } enc, err := zstd.NewWriter(nil, opts...) if err != nil { panic(err) } r.enc = enc }) return r.enc } func (r *Repository) getZstdDecoder() *zstd.Decoder { r.allocDec.Do(func() { opts := []zstd.DOption{ // Use all available cores. zstd.WithDecoderConcurrency(0), // Limit the maximum decompressed memory. Set to a very high, // conservative value. zstd.WithDecoderMaxMemory(16 * 1024 * 1024 * 1024), } dec, err := zstd.NewReader(nil, opts...) if err != nil { panic(err) } r.dec = dec }) return r.dec } // saveAndEncrypt encrypts data and stores it to the backend as type t. If data // is small enough, it will be packed together with other small blobs. The // caller must ensure that the id matches the data. Returned is the size data // occupies in the repo (compressed or not, including the encryption overhead). func (r *Repository) saveAndEncrypt(ctx context.Context, t restic.BlobType, data []byte, id restic.ID) (size int, err error) { debug.Log("save id %v (%v, %d bytes)", id, t, len(data)) uncompressedLength := 0 if r.cfg.Version > 1 { // we have a repo v2, so compression is available. if the user opts to // not compress, we won't compress any data, but everything else is // compressed. if r.opts.Compression != CompressionOff || t != restic.DataBlob { uncompressedLength = len(data) data = r.getZstdEncoder().EncodeAll(data, nil) } } nonce := crypto.NewRandomNonce() ciphertext := make([]byte, 0, crypto.CiphertextLength(len(data))) ciphertext = append(ciphertext, nonce...) // encrypt blob ciphertext = r.key.Seal(ciphertext, nonce, data, nil) // find suitable packer and add blob var pm *packerManager switch t { case restic.TreeBlob: pm = r.treePM case restic.DataBlob: pm = r.dataPM default: panic(fmt.Sprintf("invalid type: %v", t)) } return pm.SaveBlob(ctx, t, id, ciphertext, uncompressedLength) } func (r *Repository) compressUnpacked(p []byte) ([]byte, error) { // compression is only available starting from version 2 if r.cfg.Version < 2 { return p, nil } // version byte out := []byte{2} out = r.getZstdEncoder().EncodeAll(p, out) return out, nil } func (r *Repository) decompressUnpacked(p []byte) ([]byte, error) { // compression is only available starting from version 2 if r.cfg.Version < 2 { return p, nil } if len(p) == 0 { // too short for version header return p, nil } if p[0] == '[' || p[0] == '{' { // probably raw JSON return p, nil } // version if p[0] != 2 { return nil, errors.New("not supported encoding format") } return r.getZstdDecoder().DecodeAll(p[1:], nil) } // SaveUnpacked encrypts data and stores it in the backend. Returned is the // storage hash. func (r *Repository) SaveUnpacked(ctx context.Context, t restic.FileType, p []byte) (id restic.ID, err error) { if t != restic.ConfigFile { p, err = r.compressUnpacked(p) if err != nil { return restic.ID{}, err } } ciphertext := crypto.NewBlobBuffer(len(p)) ciphertext = ciphertext[:0] nonce := crypto.NewRandomNonce() ciphertext = append(ciphertext, nonce...) ciphertext = r.key.Seal(ciphertext, nonce, p, nil) if t == restic.ConfigFile { id = restic.ID{} } else { id = restic.Hash(ciphertext) } h := restic.Handle{Type: t, Name: id.String()} err = r.be.Save(ctx, h, restic.NewByteReader(ciphertext, r.be.Hasher())) if err != nil { debug.Log("error saving blob %v: %v", h, err) return restic.ID{}, err } debug.Log("blob %v saved", h) return id, nil } // Flush saves all remaining packs and the index func (r *Repository) Flush(ctx context.Context) error { if err := r.flushPacks(ctx); err != nil { return err } // Save index after flushing only if noAutoIndexUpdate is not set if r.noAutoIndexUpdate { return nil } return r.idx.SaveIndex(ctx, r) } func (r *Repository) StartPackUploader(ctx context.Context, wg *errgroup.Group) { if r.packerWg != nil { panic("uploader already started") } innerWg, ctx := errgroup.WithContext(ctx) r.packerWg = innerWg r.uploader = newPackerUploader(ctx, innerWg, r, r.be.Connections()) r.treePM = newPackerManager(r.key, restic.TreeBlob, r.PackSize(), r.uploader.QueuePacker) r.dataPM = newPackerManager(r.key, restic.DataBlob, r.PackSize(), r.uploader.QueuePacker) wg.Go(func() error { return innerWg.Wait() }) } // FlushPacks saves all remaining packs. func (r *Repository) flushPacks(ctx context.Context) error { if r.packerWg == nil { return nil } err := r.treePM.Flush(ctx) if err != nil { return err } err = r.dataPM.Flush(ctx) if err != nil { return err } r.uploader.TriggerShutdown() err = r.packerWg.Wait() r.treePM = nil r.dataPM = nil r.uploader = nil r.packerWg = nil return err } // Backend returns the backend for the repository. func (r *Repository) Backend() restic.Backend { return r.be } func (r *Repository) Connections() uint { return r.be.Connections() } // Index returns the currently used MasterIndex. func (r *Repository) Index() restic.MasterIndex { return r.idx } // SetIndex instructs the repository to use the given index. func (r *Repository) SetIndex(i restic.MasterIndex) error { r.idx = i.(*index.MasterIndex) return r.prepareCache() } // LoadIndex loads all index files from the backend in parallel and stores them func (r *Repository) LoadIndex(ctx context.Context, p *progress.Counter) error { debug.Log("Loading index") indexList, err := backend.MemorizeList(ctx, r.Backend(), restic.IndexFile) if err != nil { return err } if p != nil { var numIndexFiles uint64 err := indexList.List(ctx, restic.IndexFile, func(fi restic.FileInfo) error { _, err := restic.ParseID(fi.Name) if err != nil { debug.Log("unable to parse %v as an ID", fi.Name) return nil } numIndexFiles++ return nil }) if err != nil { return err } p.SetMax(numIndexFiles) defer p.Done() } err = index.ForAllIndexes(ctx, indexList, r, func(id restic.ID, idx *index.Index, oldFormat bool, err error) error { if err != nil { return err } r.idx.Insert(idx) if p != nil { p.Add(1) } return nil }) if err != nil { return err } err = r.idx.MergeFinalIndexes() if err != nil { return err } // Trigger GC to reset garbage collection threshold runtime.GC() if r.cfg.Version < 2 { // sanity check ctx, cancel := context.WithCancel(ctx) defer cancel() invalidIndex := false r.idx.Each(ctx, func(blob restic.PackedBlob) { if blob.IsCompressed() { invalidIndex = true } }) if invalidIndex { return errors.New("index uses feature not supported by repository version 1") } } // remove index files from the cache which have been removed in the repo return r.prepareCache() } // CreateIndexFromPacks creates a new index by reading all given pack files (with sizes). // The index is added to the MasterIndex but not marked as finalized. // Returned is the list of pack files which could not be read. func (r *Repository) CreateIndexFromPacks(ctx context.Context, packsize map[restic.ID]int64, p *progress.Counter) (invalid restic.IDs, err error) { var m sync.Mutex debug.Log("Loading index from pack files") // track spawned goroutines using wg, create a new context which is // cancelled as soon as an error occurs. wg, ctx := errgroup.WithContext(ctx) type FileInfo struct { restic.ID Size int64 } ch := make(chan FileInfo) // send list of pack files through ch, which is closed afterwards wg.Go(func() error { defer close(ch) for id, size := range packsize { select { case <-ctx.Done(): return ctx.Err() case ch <- FileInfo{id, size}: } } return nil }) // a worker receives an pack ID from ch, reads the pack contents, and adds them to idx worker := func() error { for fi := range ch { entries, _, err := r.ListPack(ctx, fi.ID, fi.Size) if err != nil { debug.Log("unable to list pack file %v", fi.ID.Str()) m.Lock() invalid = append(invalid, fi.ID) m.Unlock() } r.idx.StorePack(fi.ID, entries) p.Add(1) } return nil } // decoding the pack header is usually quite fast, thus we are primarily IO-bound workerCount := int(r.Connections()) // run workers on ch for i := 0; i < workerCount; i++ { wg.Go(worker) } err = wg.Wait() if err != nil { return invalid, err } return invalid, nil } // prepareCache initializes the local cache. indexIDs is the list of IDs of // index files still present in the repo. func (r *Repository) prepareCache() error { if r.Cache == nil { return nil } indexIDs := r.idx.IDs() debug.Log("prepare cache with %d index files", len(indexIDs)) // clear old index files err := r.Cache.Clear(restic.IndexFile, indexIDs) if err != nil { fmt.Fprintf(os.Stderr, "error clearing index files in cache: %v\n", err) } packs := r.idx.Packs(restic.NewIDSet()) // clear old packs err = r.Cache.Clear(restic.PackFile, packs) if err != nil { fmt.Fprintf(os.Stderr, "error clearing pack files in cache: %v\n", err) } return nil } // SearchKey finds a key with the supplied password, afterwards the config is // read and parsed. It tries at most maxKeys key files in the repo. func (r *Repository) SearchKey(ctx context.Context, password string, maxKeys int, keyHint string) error { key, err := SearchKey(ctx, r, password, maxKeys, keyHint) if err != nil { return err } r.key = key.master r.keyID = key.ID() cfg, err := restic.LoadConfig(ctx, r) if err == crypto.ErrUnauthenticated { return fmt.Errorf("config or key %v is damaged: %w", key.ID(), err) } else if err != nil { return fmt.Errorf("config cannot be loaded: %w", err) } r.setConfig(cfg) return nil } // Init creates a new master key with the supplied password, initializes and // saves the repository config. func (r *Repository) Init(ctx context.Context, version uint, password string, chunkerPolynomial *chunker.Pol) error { if version > restic.MaxRepoVersion { return fmt.Errorf("repository version %v too high", version) } if version < restic.MinRepoVersion { return fmt.Errorf("repository version %v too low", version) } _, err := r.be.Stat(ctx, restic.Handle{Type: restic.ConfigFile}) if err != nil && !r.be.IsNotExist(err) { return err } if err == nil { return errors.New("repository master key and config already initialized") } cfg, err := restic.CreateConfig(version) if err != nil { return err } if chunkerPolynomial != nil { cfg.ChunkerPolynomial = *chunkerPolynomial } return r.init(ctx, password, cfg) } // init creates a new master key with the supplied password and uses it to save // the config into the repo. func (r *Repository) init(ctx context.Context, password string, cfg restic.Config) error { key, err := createMasterKey(ctx, r, password) if err != nil { return err } r.key = key.master r.keyID = key.ID() r.setConfig(cfg) return restic.SaveConfig(ctx, r, cfg) } // Key returns the current master key. func (r *Repository) Key() *crypto.Key { return r.key } // KeyID returns the id of the current key in the backend. func (r *Repository) KeyID() restic.ID { return r.keyID } // List runs fn for all files of type t in the repo. func (r *Repository) List(ctx context.Context, t restic.FileType, fn func(restic.ID, int64) error) error { return r.be.List(ctx, t, func(fi restic.FileInfo) error { id, err := restic.ParseID(fi.Name) if err != nil { debug.Log("unable to parse %v as an ID", fi.Name) return nil } return fn(id, fi.Size) }) } // ListPack returns the list of blobs saved in the pack id and the length of // the the pack header. func (r *Repository) ListPack(ctx context.Context, id restic.ID, size int64) ([]restic.Blob, uint32, error) { h := restic.Handle{Type: restic.PackFile, Name: id.String()} return pack.List(r.Key(), backend.ReaderAt(ctx, r.Backend(), h), size) } // Delete calls backend.Delete() if implemented, and returns an error // otherwise. func (r *Repository) Delete(ctx context.Context) error { return r.be.Delete(ctx) } // Close closes the repository by closing the backend. func (r *Repository) Close() error { return r.be.Close() } // SaveBlob saves a blob of type t into the repository. // It takes care that no duplicates are saved; this can be overwritten // by setting storeDuplicate to true. // If id is the null id, it will be computed and returned. // Also returns if the blob was already known before. // If the blob was not known before, it returns the number of bytes the blob // occupies in the repo (compressed or not, including encryption overhead). func (r *Repository) SaveBlob(ctx context.Context, t restic.BlobType, buf []byte, id restic.ID, storeDuplicate bool) (newID restic.ID, known bool, size int, err error) { // compute plaintext hash if not already set if id.IsNull() { // Special case the hash calculation for all zero chunks. This is especially // useful for sparse files containing large all zero regions. For these we can // process chunks as fast as we can read the from disk. if len(buf) == chunker.MinSize && restic.ZeroPrefixLen(buf) == chunker.MinSize { newID = ZeroChunk() } else { newID = restic.Hash(buf) } } else { newID = id } // first try to add to pending blobs; if not successful, this blob is already known known = !r.idx.AddPending(restic.BlobHandle{ID: newID, Type: t}) // only save when needed or explicitly told if !known || storeDuplicate { size, err = r.saveAndEncrypt(ctx, t, buf, newID) } return newID, known, size, err } type BackendLoadFn func(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error // Skip sections with more than 4MB unused blobs const maxUnusedRange = 4 * 1024 * 1024 // StreamPack loads the listed blobs from the specified pack file. The plaintext blob is passed to // the handleBlobFn callback or an error if decryption failed or the blob hash does not match. In // case of download errors handleBlobFn might be called multiple times for the same blob. If the // callback returns an error, then StreamPack will abort and not retry it. func StreamPack(ctx context.Context, beLoad BackendLoadFn, key *crypto.Key, packID restic.ID, blobs []restic.Blob, handleBlobFn func(blob restic.BlobHandle, buf []byte, err error) error) error { if len(blobs) == 0 { // nothing to do return nil } sort.Slice(blobs, func(i, j int) bool { return blobs[i].Offset < blobs[j].Offset }) lowerIdx := 0 lastPos := blobs[0].Offset for i := 0; i < len(blobs); i++ { if blobs[i].Offset < lastPos { // don't wait for streamPackPart to fail return errors.Errorf("overlapping blobs in pack %v", packID) } if blobs[i].Offset-lastPos > maxUnusedRange { // load everything up to the skipped file section err := streamPackPart(ctx, beLoad, key, packID, blobs[lowerIdx:i], handleBlobFn) if err != nil { return err } lowerIdx = i } lastPos = blobs[i].Offset + blobs[i].Length } // load remainder return streamPackPart(ctx, beLoad, key, packID, blobs[lowerIdx:], handleBlobFn) } func streamPackPart(ctx context.Context, beLoad BackendLoadFn, key *crypto.Key, packID restic.ID, blobs []restic.Blob, handleBlobFn func(blob restic.BlobHandle, buf []byte, err error) error) error { h := restic.Handle{Type: restic.PackFile, Name: packID.String(), IsMetadata: false} dataStart := blobs[0].Offset dataEnd := blobs[len(blobs)-1].Offset + blobs[len(blobs)-1].Length debug.Log("streaming pack %v (%d to %d bytes), blobs: %v", packID, dataStart, dataEnd, len(blobs)) dec, err := zstd.NewReader(nil) if err != nil { panic(dec) } defer dec.Close() ctx, cancel := context.WithCancel(ctx) // stream blobs in pack err = beLoad(ctx, h, int(dataEnd-dataStart), int64(dataStart), func(rd io.Reader) error { // prevent callbacks after cancelation if ctx.Err() != nil { return ctx.Err() } bufferSize := int(dataEnd - dataStart) if bufferSize > MaxStreamBufferSize { bufferSize = MaxStreamBufferSize } // create reader here to allow reusing the buffered reader from checker.checkData bufRd := bufio.NewReaderSize(rd, bufferSize) currentBlobEnd := dataStart var buf []byte var decode []byte for _, entry := range blobs { skipBytes := int(entry.Offset - currentBlobEnd) if skipBytes < 0 { return errors.Errorf("overlapping blobs in pack %v", packID) } _, err := bufRd.Discard(skipBytes) if err != nil { return err } h := restic.BlobHandle{ID: entry.ID, Type: entry.Type} debug.Log(" process blob %v, skipped %d, %v", h, skipBytes, entry) if uint(cap(buf)) < entry.Length { buf = make([]byte, entry.Length) } buf = buf[:entry.Length] n, err := io.ReadFull(bufRd, buf) if err != nil { debug.Log(" read error %v", err) return errors.Wrap(err, "ReadFull") } if n != len(buf) { return errors.Errorf("read blob %v from %v: not enough bytes read, want %v, got %v", h, packID.Str(), len(buf), n) } currentBlobEnd = entry.Offset + entry.Length if int(entry.Length) <= key.NonceSize() { debug.Log("%v", blobs) return errors.Errorf("invalid blob length %v", entry) } // decryption errors are likely permanent, give the caller a chance to skip them nonce, ciphertext := buf[:key.NonceSize()], buf[key.NonceSize():] plaintext, err := key.Open(ciphertext[:0], nonce, ciphertext, nil) if err == nil && entry.IsCompressed() { // DecodeAll will allocate a slice if it is not large enough since it // knows the decompressed size (because we're using EncodeAll) decode, err = dec.DecodeAll(plaintext, decode[:0]) plaintext = decode if err != nil { err = errors.Errorf("decompressing blob %v failed: %v", h, err) } } if err == nil { id := restic.Hash(plaintext) if !id.Equal(entry.ID) { debug.Log("read blob %v/%v from %v: wrong data returned, hash is %v", h.Type, h.ID, packID.Str(), id) err = errors.Errorf("read blob %v from %v: wrong data returned, hash is %v", h, packID.Str(), id) } } err = handleBlobFn(entry.BlobHandle, plaintext, err) if err != nil { cancel() return backoff.Permanent(err) } } return nil }) return errors.Wrap(err, "StreamPack") } var zeroChunkOnce sync.Once var zeroChunkID restic.ID // ZeroChunk computes and returns (cached) the ID of an all-zero chunk with size chunker.MinSize func ZeroChunk() restic.ID { zeroChunkOnce.Do(func() { zeroChunkID = restic.Hash(make([]byte, chunker.MinSize)) }) return zeroChunkID }