forked from TrueCloudLab/restic
d8ea10db8c
Add comment that the check is based on the stdlib HTTP2 client. Refactor the checks into a function. Return an error if the value in the Content-Length header cannot be parsed.
532 lines
13 KiB
Go
532 lines
13 KiB
Go
package rest
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import (
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"context"
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"net/textproto"
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"net/url"
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"path"
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"strconv"
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"strings"
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"golang.org/x/net/context/ctxhttp"
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"github.com/restic/restic/internal/backend"
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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/restic"
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"github.com/cenkalti/backoff/v4"
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)
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// make sure the rest backend implements restic.Backend
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var _ restic.Backend = &Backend{}
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// Backend uses the REST protocol to access data stored on a server.
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type Backend struct {
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url *url.URL
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sem *backend.Semaphore
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client *http.Client
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backend.Layout
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}
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// the REST API protocol version is decided by HTTP request headers, these are the constants.
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const (
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ContentTypeV1 = "application/vnd.x.restic.rest.v1"
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ContentTypeV2 = "application/vnd.x.restic.rest.v2"
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)
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// Open opens the REST backend with the given config.
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func Open(cfg Config, rt http.RoundTripper) (*Backend, error) {
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client := &http.Client{Transport: rt}
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sem, err := backend.NewSemaphore(cfg.Connections)
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if err != nil {
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return nil, err
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}
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// use url without trailing slash for layout
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url := cfg.URL.String()
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if url[len(url)-1] == '/' {
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url = url[:len(url)-1]
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}
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be := &Backend{
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url: cfg.URL,
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client: client,
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Layout: &backend.RESTLayout{URL: url, Join: path.Join},
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sem: sem,
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}
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return be, nil
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}
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// Create creates a new REST on server configured in config.
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func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
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be, err := Open(cfg, rt)
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if err != nil {
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return nil, err
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}
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_, err = be.Stat(ctx, restic.Handle{Type: restic.ConfigFile})
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if err == nil {
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return nil, errors.Fatal("config file already exists")
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}
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url := *cfg.URL
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values := url.Query()
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values.Set("create", "true")
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url.RawQuery = values.Encode()
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resp, err := be.client.Post(url.String(), "binary/octet-stream", strings.NewReader(""))
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, errors.Fatalf("server response unexpected: %v (%v)", resp.Status, resp.StatusCode)
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}
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_, err = io.Copy(ioutil.Discard, resp.Body)
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if err != nil {
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return nil, err
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}
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err = resp.Body.Close()
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if err != nil {
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return nil, err
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}
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return be, nil
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}
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// Location returns this backend's location (the server's URL).
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func (b *Backend) Location() string {
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return b.url.String()
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}
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// Save stores data in the backend at the handle.
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func (b *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
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if err := h.Valid(); err != nil {
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return backoff.Permanent(err)
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}
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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// make sure that client.Post() cannot close the reader by wrapping it
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req, err := http.NewRequest(http.MethodPost, b.Filename(h), ioutil.NopCloser(rd))
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if err != nil {
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return errors.Wrap(err, "NewRequest")
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}
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req.Header.Set("Content-Type", "application/octet-stream")
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req.Header.Set("Accept", ContentTypeV2)
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// explicitly set the content length, this prevents chunked encoding and
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// let's the server know what's coming.
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req.ContentLength = rd.Length()
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b.sem.GetToken()
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resp, err := ctxhttp.Do(ctx, b.client, req)
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b.sem.ReleaseToken()
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var cerr error
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if resp != nil {
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_, _ = io.Copy(ioutil.Discard, resp.Body)
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cerr = resp.Body.Close()
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}
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if err != nil {
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return errors.Wrap(err, "client.Post")
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}
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if resp.StatusCode != 200 {
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return errors.Errorf("server response unexpected: %v (%v)", resp.Status, resp.StatusCode)
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}
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return errors.Wrap(cerr, "Close")
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}
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// ErrIsNotExist is returned whenever the requested file does not exist on the
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// server.
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type ErrIsNotExist struct {
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restic.Handle
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}
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func (e ErrIsNotExist) Error() string {
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return fmt.Sprintf("%v does not exist", e.Handle)
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}
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// IsNotExist returns true if the error was caused by a non-existing file.
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func (b *Backend) IsNotExist(err error) bool {
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err = errors.Cause(err)
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_, ok := err.(ErrIsNotExist)
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return ok
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}
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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 *Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
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r, err := b.openReader(ctx, h, length, offset)
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if err != nil {
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return err
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}
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err = fn(r)
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if err != nil {
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_ = r.Close() // ignore error here
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return err
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}
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// Note: readerat.ReadAt() (the fn) uses io.ReadFull() that doesn't
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// wait for EOF after reading body. Due to HTTP/2 stream multiplexing
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// and goroutine timings the EOF frame arrives from server (eg. rclone)
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// with a delay after reading body. Immediate close might trigger
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// HTTP/2 stream reset resulting in the *stream closed* error on server,
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// so we wait for EOF before closing body.
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var buf [1]byte
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_, err = r.Read(buf[:])
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if err == io.EOF {
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err = nil
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}
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if e := r.Close(); err == nil {
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err = e
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}
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return err
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}
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// checkContentLength returns an error if the server returned a value in the
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// Content-Length header in an HTTP2 connection, but closed the connection
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// before any data was sent.
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//
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// This is a workaround for https://github.com/golang/go/issues/46071
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//
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// See also https://forum.restic.net/t/http2-stream-closed-connection-reset-context-canceled/3743/10
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func checkContentLength(resp *http.Response) error {
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// the following code is based on
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// https://github.com/golang/go/blob/b7a85e0003cedb1b48a1fd3ae5b746ec6330102e/src/net/http/h2_bundle.go#L8646
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if resp.ContentLength != 0 {
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return nil
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}
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if resp.ProtoMajor != 2 && resp.ProtoMinor != 0 {
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return nil
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}
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if len(resp.Header[textproto.CanonicalMIMEHeaderKey("Content-Length")]) != 1 {
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return nil
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}
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// make sure that if the server returned a content length and we can
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// parse it, it is really zero, otherwise return an error
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contentLength := resp.Header.Get("Content-Length")
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cl, err := strconv.ParseUint(contentLength, 10, 63)
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if err != nil {
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return fmt.Errorf("unable to parse Content-Length %q: %w", contentLength, err)
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}
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if cl != 0 {
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return errors.Errorf("unexpected EOF: got 0 instead of %v bytes", cl)
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}
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return nil
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}
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func (b *Backend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
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debug.Log("Load %v, length %v, offset %v", h, length, offset)
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if err := h.Valid(); err != nil {
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return nil, backoff.Permanent(err)
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}
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if offset < 0 {
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return nil, errors.New("offset is negative")
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}
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if length < 0 {
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return nil, errors.Errorf("invalid length %d", length)
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}
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req, err := http.NewRequest("GET", b.Filename(h), nil)
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if err != nil {
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return nil, errors.Wrap(err, "http.NewRequest")
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}
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byteRange := fmt.Sprintf("bytes=%d-", offset)
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if length > 0 {
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byteRange = fmt.Sprintf("bytes=%d-%d", offset, offset+int64(length)-1)
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}
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req.Header.Set("Range", byteRange)
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req.Header.Set("Accept", ContentTypeV2)
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debug.Log("Load(%v) send range %v", h, byteRange)
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b.sem.GetToken()
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resp, err := ctxhttp.Do(ctx, b.client, req)
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b.sem.ReleaseToken()
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if err != nil {
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if resp != nil {
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_, _ = io.Copy(ioutil.Discard, resp.Body)
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_ = resp.Body.Close()
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}
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return nil, errors.Wrap(err, "client.Do")
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}
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if resp.StatusCode == http.StatusNotFound {
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_ = resp.Body.Close()
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return nil, ErrIsNotExist{h}
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}
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if resp.StatusCode != 200 && resp.StatusCode != 206 {
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_ = resp.Body.Close()
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return nil, errors.Errorf("unexpected HTTP response (%v): %v", resp.StatusCode, resp.Status)
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}
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// workaround https://github.com/golang/go/issues/46071
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// see also https://forum.restic.net/t/http2-stream-closed-connection-reset-context-canceled/3743/10
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err = checkContentLength(resp)
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if err != nil {
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_ = resp.Body.Close()
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return nil, err
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}
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return resp.Body, nil
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}
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// Stat returns information about a blob.
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func (b *Backend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
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if err := h.Valid(); err != nil {
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return restic.FileInfo{}, backoff.Permanent(err)
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}
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req, err := http.NewRequest(http.MethodHead, b.Filename(h), nil)
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if err != nil {
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return restic.FileInfo{}, errors.Wrap(err, "NewRequest")
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}
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req.Header.Set("Accept", ContentTypeV2)
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b.sem.GetToken()
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resp, err := ctxhttp.Do(ctx, b.client, req)
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b.sem.ReleaseToken()
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if err != nil {
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return restic.FileInfo{}, errors.Wrap(err, "client.Head")
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}
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_, _ = io.Copy(ioutil.Discard, resp.Body)
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if err = resp.Body.Close(); err != nil {
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return restic.FileInfo{}, errors.Wrap(err, "Close")
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}
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if resp.StatusCode == http.StatusNotFound {
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_ = resp.Body.Close()
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return restic.FileInfo{}, ErrIsNotExist{h}
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}
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if resp.StatusCode != 200 {
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return restic.FileInfo{}, errors.Errorf("unexpected HTTP response (%v): %v", resp.StatusCode, resp.Status)
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}
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if resp.ContentLength < 0 {
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return restic.FileInfo{}, errors.New("negative content length")
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}
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bi := restic.FileInfo{
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Size: resp.ContentLength,
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Name: h.Name,
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}
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return bi, nil
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}
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// Test returns true if a blob of the given type and name exists in the backend.
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func (b *Backend) Test(ctx context.Context, h restic.Handle) (bool, error) {
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_, err := b.Stat(ctx, h)
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if err != nil {
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return false, nil
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}
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return true, 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 *Backend) Remove(ctx context.Context, h restic.Handle) error {
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if err := h.Valid(); err != nil {
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return backoff.Permanent(err)
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}
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req, err := http.NewRequest("DELETE", b.Filename(h), nil)
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if err != nil {
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return errors.Wrap(err, "http.NewRequest")
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}
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req.Header.Set("Accept", ContentTypeV2)
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b.sem.GetToken()
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resp, err := ctxhttp.Do(ctx, b.client, req)
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b.sem.ReleaseToken()
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if err != nil {
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return errors.Wrap(err, "client.Do")
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}
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if resp.StatusCode == http.StatusNotFound {
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_ = resp.Body.Close()
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return ErrIsNotExist{h}
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}
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if resp.StatusCode != 200 {
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return errors.Errorf("blob not removed, server response: %v (%v)", resp.Status, resp.StatusCode)
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}
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_, err = io.Copy(ioutil.Discard, resp.Body)
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if err != nil {
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return errors.Wrap(err, "Copy")
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}
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return errors.Wrap(resp.Body.Close(), "Close")
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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 *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
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url := b.Dirname(restic.Handle{Type: t})
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if !strings.HasSuffix(url, "/") {
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url += "/"
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}
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req, err := http.NewRequest(http.MethodGet, url, nil)
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if err != nil {
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return errors.Wrap(err, "NewRequest")
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}
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req.Header.Set("Accept", ContentTypeV2)
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b.sem.GetToken()
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resp, err := ctxhttp.Do(ctx, b.client, req)
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b.sem.ReleaseToken()
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if err != nil {
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return errors.Wrap(err, "List")
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}
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if resp.StatusCode != 200 {
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return errors.Errorf("List failed, server response: %v (%v)", resp.Status, resp.StatusCode)
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}
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if resp.Header.Get("Content-Type") == ContentTypeV2 {
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return b.listv2(ctx, t, resp, fn)
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}
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return b.listv1(ctx, t, resp, fn)
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}
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// listv1 uses the REST protocol v1, where a list HTTP request (e.g. `GET
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// /data/`) only returns the names of the files, so we need to issue an HTTP
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// HEAD request for each file.
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func (b *Backend) listv1(ctx context.Context, t restic.FileType, resp *http.Response, fn func(restic.FileInfo) error) error {
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debug.Log("parsing API v1 response")
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dec := json.NewDecoder(resp.Body)
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var list []string
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if err := dec.Decode(&list); err != nil {
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return errors.Wrap(err, "Decode")
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}
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for _, m := range list {
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fi, err := b.Stat(ctx, restic.Handle{Name: m, Type: t})
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if err != nil {
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return err
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}
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if ctx.Err() != nil {
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return ctx.Err()
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}
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fi.Name = m
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err = fn(fi)
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if err != nil {
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return err
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}
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if ctx.Err() != nil {
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return ctx.Err()
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}
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}
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return ctx.Err()
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}
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// listv2 uses the REST protocol v2, where a list HTTP request (e.g. `GET
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// /data/`) returns the names and sizes of all files.
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func (b *Backend) listv2(ctx context.Context, t restic.FileType, resp *http.Response, fn func(restic.FileInfo) error) error {
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debug.Log("parsing API v2 response")
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dec := json.NewDecoder(resp.Body)
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var list []struct {
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Name string `json:"name"`
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Size int64 `json:"size"`
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}
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if err := dec.Decode(&list); err != nil {
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return errors.Wrap(err, "Decode")
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}
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for _, item := range list {
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if ctx.Err() != nil {
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return ctx.Err()
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}
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fi := restic.FileInfo{
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Name: item.Name,
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Size: item.Size,
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}
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err := fn(fi)
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if err != nil {
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return err
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}
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if ctx.Err() != nil {
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return ctx.Err()
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}
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}
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return ctx.Err()
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}
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// Close closes all open files.
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func (b *Backend) 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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// Remove keys for a specified backend type.
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func (b *Backend) removeKeys(ctx context.Context, t restic.FileType) error {
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return b.List(ctx, t, func(fi restic.FileInfo) error {
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return b.Remove(ctx, restic.Handle{Type: t, Name: fi.Name})
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})
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}
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// Delete removes all data in the backend.
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func (b *Backend) Delete(ctx context.Context) error {
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alltypes := []restic.FileType{
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restic.PackFile,
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restic.KeyFile,
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restic.LockFile,
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restic.SnapshotFile,
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restic.IndexFile}
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for _, t := range alltypes {
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err := b.removeKeys(ctx, t)
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if err != nil {
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return nil
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}
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}
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err := b.Remove(ctx, restic.Handle{Type: restic.ConfigFile})
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if err != nil && b.IsNotExist(err) {
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return nil
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}
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return err
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}
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