package s3 import ( "bytes" "errors" "fmt" "io" "io/ioutil" "strings" "github.com/mitchellh/goamz/aws" "github.com/mitchellh/goamz/s3" "github.com/restic/restic/backend" ) const maxKeysInList = 1000 const connLimit = 10 const backendPrefix = "restic" func s3path(t backend.Type, name string) string { if t == backend.Config { return backendPrefix + "/" + string(t) } return backendPrefix + "/" + string(t) + "/" + name } type S3Backend struct { bucket *s3.Bucket connChan chan struct{} path string } // Open a backend using an S3 bucket object func OpenS3Bucket(bucket *s3.Bucket, bucketname string) *S3Backend { connChan := make(chan struct{}, connLimit) for i := 0; i < connLimit; i++ { connChan <- struct{}{} } return &S3Backend{bucket: bucket, path: bucketname, connChan: connChan} } // Open opens the s3 backend at bucket and region. func Open(regionname, bucketname string) (backend.Backend, error) { auth, err := aws.EnvAuth() if err != nil { return nil, err } client := s3.New(auth, aws.Regions[regionname]) return OpenS3Bucket(client.Bucket(bucketname), bucketname), nil } // Location returns this backend's location (the bucket name). func (be *S3Backend) Location() string { return be.path } type s3Blob struct { b *S3Backend buf *bytes.Buffer final bool } func (bb *s3Blob) Write(p []byte) (int, error) { if bb.final { return 0, errors.New("blob already closed") } n, err := bb.buf.Write(p) return n, err } func (bb *s3Blob) Read(p []byte) (int, error) { return bb.buf.Read(p) } func (bb *s3Blob) Close() error { bb.final = true bb.buf.Reset() return nil } func (bb *s3Blob) Size() uint { return uint(bb.buf.Len()) } func (bb *s3Blob) Finalize(t backend.Type, name string) error { if bb.final { return errors.New("Already finalized") } bb.final = true path := s3path(t, name) // Check key does not already exist key, err := bb.b.bucket.GetKey(path) if err == nil && key.Key == path { return errors.New("key already exists!") } <-bb.b.connChan err = bb.b.bucket.Put(path, bb.buf.Bytes(), "binary/octet-stream", "private") bb.b.connChan <- struct{}{} bb.buf.Reset() return err } // Create creates a new Blob. The data is available only after Finalize() // has been called on the returned Blob. func (be *S3Backend) Create() (backend.Blob, error) { blob := s3Blob{ b: be, buf: &bytes.Buffer{}, } return &blob, nil } // Get returns a reader that yields the content stored under the given // name. The reader should be closed after draining it. func (be *S3Backend) Get(t backend.Type, name string) (io.ReadCloser, error) { path := s3path(t, name) return be.bucket.GetReader(path) } // GetReader returns an io.ReadCloser for the Blob with the given name of // type t at offset and length. If length is 0, the reader reads until EOF. func (be *S3Backend) GetReader(t backend.Type, name string, offset, length uint) (io.ReadCloser, error) { rc, err := be.Get(t, name) if err != nil { return nil, err } n, errc := io.CopyN(ioutil.Discard, rc, int64(offset)) if errc != nil { return nil, errc } else if n != int64(offset) { return nil, fmt.Errorf("less bytes read than expected, read: %d, expected: %d", n, offset) } if length == 0 { return rc, nil } return backend.LimitReadCloser(rc, int64(length)), nil } // Test returns true if a blob of the given type and name exists in the backend. func (be *S3Backend) Test(t backend.Type, name string) (bool, error) { found := false path := s3path(t, name) key, err := be.bucket.GetKey(path) if err == nil && key.Key == path { found = true } // If error, then not found return found, nil } // Remove removes the blob with the given name and type. func (be *S3Backend) Remove(t backend.Type, name string) error { path := s3path(t, name) return be.bucket.Del(path) } // List returns a channel that yields all names of blobs of type t. A // goroutine is started for this. If the channel done is closed, sending // stops. func (be *S3Backend) List(t backend.Type, done <-chan struct{}) <-chan string { ch := make(chan string) prefix := s3path(t, "") listresp, err := be.bucket.List(prefix, "/", "", maxKeysInList) if err != nil { close(ch) return ch } matches := make([]string, len(listresp.Contents)) for idx, key := range listresp.Contents { matches[idx] = strings.TrimPrefix(key.Key, prefix) } // Continue making requests to get full list. for listresp.IsTruncated { listresp, err = be.bucket.List(prefix, "/", listresp.NextMarker, maxKeysInList) if err != nil { close(ch) return ch } for _, key := range listresp.Contents { matches = append(matches, strings.TrimPrefix(key.Key, prefix)) } } go func() { defer close(ch) for _, m := range matches { if m == "" { continue } select { case ch <- m: case <-done: return } } }() return ch } // Remove keys for a specified backend type func (be *S3Backend) removeKeys(t backend.Type) { doneChan := make(chan struct{}) for key := range be.List(backend.Data, doneChan) { be.Remove(backend.Data, key) } doneChan <- struct{}{} } // Delete removes all restic keys func (be *S3Backend) Delete() error { be.removeKeys(backend.Data) be.removeKeys(backend.Key) be.removeKeys(backend.Lock) be.removeKeys(backend.Snapshot) be.removeKeys(backend.Index) be.removeKeys(backend.Config) return nil } // Close does nothing func (be *S3Backend) Close() error { return nil }