gitea/vendor/gopkg.in/src-d/go-git.v4/remote.go

1068 lines
23 KiB
Go

package git
import (
"context"
"errors"
"fmt"
"io"
"gopkg.in/src-d/go-billy.v4/osfs"
"gopkg.in/src-d/go-git.v4/config"
"gopkg.in/src-d/go-git.v4/plumbing"
"gopkg.in/src-d/go-git.v4/plumbing/cache"
"gopkg.in/src-d/go-git.v4/plumbing/format/packfile"
"gopkg.in/src-d/go-git.v4/plumbing/object"
"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp"
"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp/capability"
"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp/sideband"
"gopkg.in/src-d/go-git.v4/plumbing/revlist"
"gopkg.in/src-d/go-git.v4/plumbing/storer"
"gopkg.in/src-d/go-git.v4/plumbing/transport"
"gopkg.in/src-d/go-git.v4/plumbing/transport/client"
"gopkg.in/src-d/go-git.v4/storage"
"gopkg.in/src-d/go-git.v4/storage/filesystem"
"gopkg.in/src-d/go-git.v4/storage/memory"
"gopkg.in/src-d/go-git.v4/utils/ioutil"
)
var (
NoErrAlreadyUpToDate = errors.New("already up-to-date")
ErrDeleteRefNotSupported = errors.New("server does not support delete-refs")
ErrForceNeeded = errors.New("some refs were not updated")
)
const (
// This describes the maximum number of commits to walk when
// computing the haves to send to a server, for each ref in the
// repo containing this remote, when not using the multi-ack
// protocol. Setting this to 0 means there is no limit.
maxHavesToVisitPerRef = 100
)
// Remote represents a connection to a remote repository.
type Remote struct {
c *config.RemoteConfig
s storage.Storer
}
func newRemote(s storage.Storer, c *config.RemoteConfig) *Remote {
return &Remote{s: s, c: c}
}
// Config returns the RemoteConfig object used to instantiate this Remote.
func (r *Remote) Config() *config.RemoteConfig {
return r.c
}
func (r *Remote) String() string {
var fetch, push string
if len(r.c.URLs) > 0 {
fetch = r.c.URLs[0]
push = r.c.URLs[0]
}
return fmt.Sprintf("%s\t%s (fetch)\n%[1]s\t%[3]s (push)", r.c.Name, fetch, push)
}
// Push performs a push to the remote. Returns NoErrAlreadyUpToDate if the
// remote was already up-to-date.
func (r *Remote) Push(o *PushOptions) error {
return r.PushContext(context.Background(), o)
}
// PushContext performs a push to the remote. Returns NoErrAlreadyUpToDate if
// the remote was already up-to-date.
//
// The provided Context must be non-nil. If the context expires before the
// operation is complete, an error is returned. The context only affects to the
// transport operations.
func (r *Remote) PushContext(ctx context.Context, o *PushOptions) (err error) {
if err := o.Validate(); err != nil {
return err
}
if o.RemoteName != r.c.Name {
return fmt.Errorf("remote names don't match: %s != %s", o.RemoteName, r.c.Name)
}
s, err := newSendPackSession(r.c.URLs[0], o.Auth)
if err != nil {
return err
}
defer ioutil.CheckClose(s, &err)
ar, err := s.AdvertisedReferences()
if err != nil {
return err
}
remoteRefs, err := ar.AllReferences()
if err != nil {
return err
}
isDelete := false
allDelete := true
for _, rs := range o.RefSpecs {
if rs.IsDelete() {
isDelete = true
} else {
allDelete = false
}
if isDelete && !allDelete {
break
}
}
if isDelete && !ar.Capabilities.Supports(capability.DeleteRefs) {
return ErrDeleteRefNotSupported
}
localRefs, err := r.references()
if err != nil {
return err
}
req, err := r.newReferenceUpdateRequest(o, localRefs, remoteRefs, ar)
if err != nil {
return err
}
if len(req.Commands) == 0 {
return NoErrAlreadyUpToDate
}
objects := objectsToPush(req.Commands)
haves, err := referencesToHashes(remoteRefs)
if err != nil {
return err
}
stop, err := r.s.Shallow()
if err != nil {
return err
}
// if we have shallow we should include this as part of the objects that
// we are aware.
haves = append(haves, stop...)
var hashesToPush []plumbing.Hash
// Avoid the expensive revlist operation if we're only doing deletes.
if !allDelete {
if r.c.IsFirstURLLocal() {
// If we're are pushing to a local repo, it might be much
// faster to use a local storage layer to get the commits
// to ignore, when calculating the object revlist.
localStorer := filesystem.NewStorage(
osfs.New(r.c.URLs[0]), cache.NewObjectLRUDefault())
hashesToPush, err = revlist.ObjectsWithStorageForIgnores(
r.s, localStorer, objects, haves)
} else {
hashesToPush, err = revlist.Objects(r.s, objects, haves)
}
if err != nil {
return err
}
}
rs, err := pushHashes(ctx, s, r.s, req, hashesToPush, r.useRefDeltas(ar))
if err != nil {
return err
}
if err = rs.Error(); err != nil {
return err
}
return r.updateRemoteReferenceStorage(req, rs)
}
func (r *Remote) useRefDeltas(ar *packp.AdvRefs) bool {
return !ar.Capabilities.Supports(capability.OFSDelta)
}
func (r *Remote) newReferenceUpdateRequest(
o *PushOptions,
localRefs []*plumbing.Reference,
remoteRefs storer.ReferenceStorer,
ar *packp.AdvRefs,
) (*packp.ReferenceUpdateRequest, error) {
req := packp.NewReferenceUpdateRequestFromCapabilities(ar.Capabilities)
if o.Progress != nil {
req.Progress = o.Progress
if ar.Capabilities.Supports(capability.Sideband64k) {
req.Capabilities.Set(capability.Sideband64k)
} else if ar.Capabilities.Supports(capability.Sideband) {
req.Capabilities.Set(capability.Sideband)
}
}
if err := r.addReferencesToUpdate(o.RefSpecs, localRefs, remoteRefs, req); err != nil {
return nil, err
}
return req, nil
}
func (r *Remote) updateRemoteReferenceStorage(
req *packp.ReferenceUpdateRequest,
result *packp.ReportStatus,
) error {
for _, spec := range r.c.Fetch {
for _, c := range req.Commands {
if !spec.Match(c.Name) {
continue
}
local := spec.Dst(c.Name)
ref := plumbing.NewHashReference(local, c.New)
switch c.Action() {
case packp.Create, packp.Update:
if err := r.s.SetReference(ref); err != nil {
return err
}
case packp.Delete:
if err := r.s.RemoveReference(local); err != nil {
return err
}
}
}
}
return nil
}
// FetchContext fetches references along with the objects necessary to complete
// their histories.
//
// Returns nil if the operation is successful, NoErrAlreadyUpToDate if there are
// no changes to be fetched, or an error.
//
// The provided Context must be non-nil. If the context expires before the
// operation is complete, an error is returned. The context only affects to the
// transport operations.
func (r *Remote) FetchContext(ctx context.Context, o *FetchOptions) error {
_, err := r.fetch(ctx, o)
return err
}
// Fetch fetches references along with the objects necessary to complete their
// histories.
//
// Returns nil if the operation is successful, NoErrAlreadyUpToDate if there are
// no changes to be fetched, or an error.
func (r *Remote) Fetch(o *FetchOptions) error {
return r.FetchContext(context.Background(), o)
}
func (r *Remote) fetch(ctx context.Context, o *FetchOptions) (sto storer.ReferenceStorer, err error) {
if o.RemoteName == "" {
o.RemoteName = r.c.Name
}
if err = o.Validate(); err != nil {
return nil, err
}
if len(o.RefSpecs) == 0 {
o.RefSpecs = r.c.Fetch
}
s, err := newUploadPackSession(r.c.URLs[0], o.Auth)
if err != nil {
return nil, err
}
defer ioutil.CheckClose(s, &err)
ar, err := s.AdvertisedReferences()
if err != nil {
return nil, err
}
req, err := r.newUploadPackRequest(o, ar)
if err != nil {
return nil, err
}
remoteRefs, err := ar.AllReferences()
if err != nil {
return nil, err
}
localRefs, err := r.references()
if err != nil {
return nil, err
}
refs, err := calculateRefs(o.RefSpecs, remoteRefs, o.Tags)
if err != nil {
return nil, err
}
req.Wants, err = getWants(r.s, refs)
if len(req.Wants) > 0 {
req.Haves, err = getHaves(localRefs, remoteRefs, r.s)
if err != nil {
return nil, err
}
if err = r.fetchPack(ctx, o, s, req); err != nil {
return nil, err
}
}
updated, err := r.updateLocalReferenceStorage(o.RefSpecs, refs, remoteRefs, o.Tags, o.Force)
if err != nil {
return nil, err
}
if !updated {
return remoteRefs, NoErrAlreadyUpToDate
}
return remoteRefs, nil
}
func newUploadPackSession(url string, auth transport.AuthMethod) (transport.UploadPackSession, error) {
c, ep, err := newClient(url)
if err != nil {
return nil, err
}
return c.NewUploadPackSession(ep, auth)
}
func newSendPackSession(url string, auth transport.AuthMethod) (transport.ReceivePackSession, error) {
c, ep, err := newClient(url)
if err != nil {
return nil, err
}
return c.NewReceivePackSession(ep, auth)
}
func newClient(url string) (transport.Transport, *transport.Endpoint, error) {
ep, err := transport.NewEndpoint(url)
if err != nil {
return nil, nil, err
}
c, err := client.NewClient(ep)
if err != nil {
return nil, nil, err
}
return c, ep, err
}
func (r *Remote) fetchPack(ctx context.Context, o *FetchOptions, s transport.UploadPackSession,
req *packp.UploadPackRequest) (err error) {
reader, err := s.UploadPack(ctx, req)
if err != nil {
return err
}
defer ioutil.CheckClose(reader, &err)
if err = r.updateShallow(o, reader); err != nil {
return err
}
if err = packfile.UpdateObjectStorage(r.s,
buildSidebandIfSupported(req.Capabilities, reader, o.Progress),
); err != nil {
return err
}
return err
}
func (r *Remote) addReferencesToUpdate(
refspecs []config.RefSpec,
localRefs []*plumbing.Reference,
remoteRefs storer.ReferenceStorer,
req *packp.ReferenceUpdateRequest,
) error {
// This references dictionary will be used to search references by name.
refsDict := make(map[string]*plumbing.Reference)
for _, ref := range localRefs {
refsDict[ref.Name().String()] = ref
}
for _, rs := range refspecs {
if rs.IsDelete() {
if err := r.deleteReferences(rs, remoteRefs, req); err != nil {
return err
}
} else {
err := r.addOrUpdateReferences(rs, localRefs, refsDict, remoteRefs, req)
if err != nil {
return err
}
}
}
return nil
}
func (r *Remote) addOrUpdateReferences(
rs config.RefSpec,
localRefs []*plumbing.Reference,
refsDict map[string]*plumbing.Reference,
remoteRefs storer.ReferenceStorer,
req *packp.ReferenceUpdateRequest,
) error {
// If it is not a wilcard refspec we can directly search for the reference
// in the references dictionary.
if !rs.IsWildcard() {
ref, ok := refsDict[rs.Src()]
if !ok {
return nil
}
return r.addReferenceIfRefSpecMatches(rs, remoteRefs, ref, req)
}
for _, ref := range localRefs {
err := r.addReferenceIfRefSpecMatches(rs, remoteRefs, ref, req)
if err != nil {
return err
}
}
return nil
}
func (r *Remote) deleteReferences(rs config.RefSpec,
remoteRefs storer.ReferenceStorer, req *packp.ReferenceUpdateRequest) error {
iter, err := remoteRefs.IterReferences()
if err != nil {
return err
}
return iter.ForEach(func(ref *plumbing.Reference) error {
if ref.Type() != plumbing.HashReference {
return nil
}
if rs.Dst("") != ref.Name() {
return nil
}
cmd := &packp.Command{
Name: ref.Name(),
Old: ref.Hash(),
New: plumbing.ZeroHash,
}
req.Commands = append(req.Commands, cmd)
return nil
})
}
func (r *Remote) addReferenceIfRefSpecMatches(rs config.RefSpec,
remoteRefs storer.ReferenceStorer, localRef *plumbing.Reference,
req *packp.ReferenceUpdateRequest) error {
if localRef.Type() != plumbing.HashReference {
return nil
}
if !rs.Match(localRef.Name()) {
return nil
}
cmd := &packp.Command{
Name: rs.Dst(localRef.Name()),
Old: plumbing.ZeroHash,
New: localRef.Hash(),
}
remoteRef, err := remoteRefs.Reference(cmd.Name)
if err == nil {
if remoteRef.Type() != plumbing.HashReference {
//TODO: check actual git behavior here
return nil
}
cmd.Old = remoteRef.Hash()
} else if err != plumbing.ErrReferenceNotFound {
return err
}
if cmd.Old == cmd.New {
return nil
}
if !rs.IsForceUpdate() {
if err := checkFastForwardUpdate(r.s, remoteRefs, cmd); err != nil {
return err
}
}
req.Commands = append(req.Commands, cmd)
return nil
}
func (r *Remote) references() ([]*plumbing.Reference, error) {
var localRefs []*plumbing.Reference
iter, err := r.s.IterReferences()
if err != nil {
return nil, err
}
for {
ref, err := iter.Next()
if err == io.EOF {
break
}
if err != nil {
return nil, err
}
localRefs = append(localRefs, ref)
}
return localRefs, nil
}
func getRemoteRefsFromStorer(remoteRefStorer storer.ReferenceStorer) (
map[plumbing.Hash]bool, error) {
remoteRefs := map[plumbing.Hash]bool{}
iter, err := remoteRefStorer.IterReferences()
if err != nil {
return nil, err
}
err = iter.ForEach(func(ref *plumbing.Reference) error {
if ref.Type() != plumbing.HashReference {
return nil
}
remoteRefs[ref.Hash()] = true
return nil
})
if err != nil {
return nil, err
}
return remoteRefs, nil
}
// getHavesFromRef populates the given `haves` map with the given
// reference, and up to `maxHavesToVisitPerRef` ancestor commits.
func getHavesFromRef(
ref *plumbing.Reference,
remoteRefs map[plumbing.Hash]bool,
s storage.Storer,
haves map[plumbing.Hash]bool,
) error {
h := ref.Hash()
if haves[h] {
return nil
}
// No need to load the commit if we know the remote already
// has this hash.
if remoteRefs[h] {
haves[h] = true
return nil
}
commit, err := object.GetCommit(s, h)
if err != nil {
// Ignore the error if this isn't a commit.
haves[ref.Hash()] = true
return nil
}
// Until go-git supports proper commit negotiation during an
// upload pack request, include up to `maxHavesToVisitPerRef`
// commits from the history of each ref.
walker := object.NewCommitPreorderIter(commit, haves, nil)
toVisit := maxHavesToVisitPerRef
return walker.ForEach(func(c *object.Commit) error {
haves[c.Hash] = true
toVisit--
// If toVisit starts out at 0 (indicating there is no
// max), then it will be negative here and we won't stop
// early.
if toVisit == 0 || remoteRefs[c.Hash] {
return storer.ErrStop
}
return nil
})
}
func getHaves(
localRefs []*plumbing.Reference,
remoteRefStorer storer.ReferenceStorer,
s storage.Storer,
) ([]plumbing.Hash, error) {
haves := map[plumbing.Hash]bool{}
// Build a map of all the remote references, to avoid loading too
// many parent commits for references we know don't need to be
// transferred.
remoteRefs, err := getRemoteRefsFromStorer(remoteRefStorer)
if err != nil {
return nil, err
}
for _, ref := range localRefs {
if haves[ref.Hash()] {
continue
}
if ref.Type() != plumbing.HashReference {
continue
}
err = getHavesFromRef(ref, remoteRefs, s, haves)
if err != nil {
return nil, err
}
}
var result []plumbing.Hash
for h := range haves {
result = append(result, h)
}
return result, nil
}
const refspecAllTags = "+refs/tags/*:refs/tags/*"
func calculateRefs(
spec []config.RefSpec,
remoteRefs storer.ReferenceStorer,
tagMode TagMode,
) (memory.ReferenceStorage, error) {
if tagMode == AllTags {
spec = append(spec, refspecAllTags)
}
refs := make(memory.ReferenceStorage)
for _, s := range spec {
if err := doCalculateRefs(s, remoteRefs, refs); err != nil {
return nil, err
}
}
return refs, nil
}
func doCalculateRefs(
s config.RefSpec,
remoteRefs storer.ReferenceStorer,
refs memory.ReferenceStorage,
) error {
iter, err := remoteRefs.IterReferences()
if err != nil {
return err
}
var matched bool
err = iter.ForEach(func(ref *plumbing.Reference) error {
if !s.Match(ref.Name()) {
return nil
}
if ref.Type() == plumbing.SymbolicReference {
target, err := storer.ResolveReference(remoteRefs, ref.Name())
if err != nil {
return err
}
ref = plumbing.NewHashReference(ref.Name(), target.Hash())
}
if ref.Type() != plumbing.HashReference {
return nil
}
matched = true
if err := refs.SetReference(ref); err != nil {
return err
}
if !s.IsWildcard() {
return storer.ErrStop
}
return nil
})
if !matched && !s.IsWildcard() {
return fmt.Errorf("couldn't find remote ref %q", s.Src())
}
return err
}
func getWants(localStorer storage.Storer, refs memory.ReferenceStorage) ([]plumbing.Hash, error) {
wants := map[plumbing.Hash]bool{}
for _, ref := range refs {
hash := ref.Hash()
exists, err := objectExists(localStorer, ref.Hash())
if err != nil {
return nil, err
}
if !exists {
wants[hash] = true
}
}
var result []plumbing.Hash
for h := range wants {
result = append(result, h)
}
return result, nil
}
func objectExists(s storer.EncodedObjectStorer, h plumbing.Hash) (bool, error) {
_, err := s.EncodedObject(plumbing.AnyObject, h)
if err == plumbing.ErrObjectNotFound {
return false, nil
}
return true, err
}
func checkFastForwardUpdate(s storer.EncodedObjectStorer, remoteRefs storer.ReferenceStorer, cmd *packp.Command) error {
if cmd.Old == plumbing.ZeroHash {
_, err := remoteRefs.Reference(cmd.Name)
if err == plumbing.ErrReferenceNotFound {
return nil
}
if err != nil {
return err
}
return fmt.Errorf("non-fast-forward update: %s", cmd.Name.String())
}
ff, err := isFastForward(s, cmd.Old, cmd.New)
if err != nil {
return err
}
if !ff {
return fmt.Errorf("non-fast-forward update: %s", cmd.Name.String())
}
return nil
}
func isFastForward(s storer.EncodedObjectStorer, old, new plumbing.Hash) (bool, error) {
c, err := object.GetCommit(s, new)
if err != nil {
return false, err
}
found := false
iter := object.NewCommitPreorderIter(c, nil, nil)
err = iter.ForEach(func(c *object.Commit) error {
if c.Hash != old {
return nil
}
found = true
return storer.ErrStop
})
return found, err
}
func (r *Remote) newUploadPackRequest(o *FetchOptions,
ar *packp.AdvRefs) (*packp.UploadPackRequest, error) {
req := packp.NewUploadPackRequestFromCapabilities(ar.Capabilities)
if o.Depth != 0 {
req.Depth = packp.DepthCommits(o.Depth)
if err := req.Capabilities.Set(capability.Shallow); err != nil {
return nil, err
}
}
if o.Progress == nil && ar.Capabilities.Supports(capability.NoProgress) {
if err := req.Capabilities.Set(capability.NoProgress); err != nil {
return nil, err
}
}
isWildcard := true
for _, s := range o.RefSpecs {
if !s.IsWildcard() {
isWildcard = false
break
}
}
if isWildcard && o.Tags == TagFollowing && ar.Capabilities.Supports(capability.IncludeTag) {
if err := req.Capabilities.Set(capability.IncludeTag); err != nil {
return nil, err
}
}
return req, nil
}
func buildSidebandIfSupported(l *capability.List, reader io.Reader, p sideband.Progress) io.Reader {
var t sideband.Type
switch {
case l.Supports(capability.Sideband):
t = sideband.Sideband
case l.Supports(capability.Sideband64k):
t = sideband.Sideband64k
default:
return reader
}
d := sideband.NewDemuxer(t, reader)
d.Progress = p
return d
}
func (r *Remote) updateLocalReferenceStorage(
specs []config.RefSpec,
fetchedRefs, remoteRefs memory.ReferenceStorage,
tagMode TagMode,
force bool,
) (updated bool, err error) {
isWildcard := true
forceNeeded := false
for _, spec := range specs {
if !spec.IsWildcard() {
isWildcard = false
}
for _, ref := range fetchedRefs {
if !spec.Match(ref.Name()) {
continue
}
if ref.Type() != plumbing.HashReference {
continue
}
localName := spec.Dst(ref.Name())
old, _ := storer.ResolveReference(r.s, localName)
new := plumbing.NewHashReference(localName, ref.Hash())
// If the ref exists locally as a branch and force is not specified,
// only update if the new ref is an ancestor of the old
if old != nil && old.Name().IsBranch() && !force && !spec.IsForceUpdate() {
ff, err := isFastForward(r.s, old.Hash(), new.Hash())
if err != nil {
return updated, err
}
if !ff {
forceNeeded = true
continue
}
}
refUpdated, err := checkAndUpdateReferenceStorerIfNeeded(r.s, new, old)
if err != nil {
return updated, err
}
if refUpdated {
updated = true
}
}
}
if tagMode == NoTags {
return updated, nil
}
tags := fetchedRefs
if isWildcard {
tags = remoteRefs
}
tagUpdated, err := r.buildFetchedTags(tags)
if err != nil {
return updated, err
}
if tagUpdated {
updated = true
}
if err == nil && forceNeeded {
err = ErrForceNeeded
}
return
}
func (r *Remote) buildFetchedTags(refs memory.ReferenceStorage) (updated bool, err error) {
for _, ref := range refs {
if !ref.Name().IsTag() {
continue
}
_, err := r.s.EncodedObject(plumbing.AnyObject, ref.Hash())
if err == plumbing.ErrObjectNotFound {
continue
}
if err != nil {
return false, err
}
refUpdated, err := updateReferenceStorerIfNeeded(r.s, ref)
if err != nil {
return updated, err
}
if refUpdated {
updated = true
}
}
return
}
// List the references on the remote repository.
func (r *Remote) List(o *ListOptions) (rfs []*plumbing.Reference, err error) {
s, err := newUploadPackSession(r.c.URLs[0], o.Auth)
if err != nil {
return nil, err
}
defer ioutil.CheckClose(s, &err)
ar, err := s.AdvertisedReferences()
if err != nil {
return nil, err
}
allRefs, err := ar.AllReferences()
if err != nil {
return nil, err
}
refs, err := allRefs.IterReferences()
if err != nil {
return nil, err
}
var resultRefs []*plumbing.Reference
refs.ForEach(func(ref *plumbing.Reference) error {
resultRefs = append(resultRefs, ref)
return nil
})
return resultRefs, nil
}
func objectsToPush(commands []*packp.Command) []plumbing.Hash {
var objects []plumbing.Hash
for _, cmd := range commands {
if cmd.New == plumbing.ZeroHash {
continue
}
objects = append(objects, cmd.New)
}
return objects
}
func referencesToHashes(refs storer.ReferenceStorer) ([]plumbing.Hash, error) {
iter, err := refs.IterReferences()
if err != nil {
return nil, err
}
var hs []plumbing.Hash
err = iter.ForEach(func(ref *plumbing.Reference) error {
if ref.Type() != plumbing.HashReference {
return nil
}
hs = append(hs, ref.Hash())
return nil
})
if err != nil {
return nil, err
}
return hs, nil
}
func pushHashes(
ctx context.Context,
sess transport.ReceivePackSession,
s storage.Storer,
req *packp.ReferenceUpdateRequest,
hs []plumbing.Hash,
useRefDeltas bool,
) (*packp.ReportStatus, error) {
rd, wr := io.Pipe()
req.Packfile = rd
config, err := s.Config()
if err != nil {
return nil, err
}
done := make(chan error)
go func() {
e := packfile.NewEncoder(wr, s, useRefDeltas)
if _, err := e.Encode(hs, config.Pack.Window); err != nil {
done <- wr.CloseWithError(err)
return
}
done <- wr.Close()
}()
rs, err := sess.ReceivePack(ctx, req)
if err != nil {
return nil, err
}
if err := <-done; err != nil {
return nil, err
}
return rs, nil
}
func (r *Remote) updateShallow(o *FetchOptions, resp *packp.UploadPackResponse) error {
if o.Depth == 0 || len(resp.Shallows) == 0 {
return nil
}
shallows, err := r.s.Shallow()
if err != nil {
return err
}
outer:
for _, s := range resp.Shallows {
for _, oldS := range shallows {
if s == oldS {
continue outer
}
}
shallows = append(shallows, s)
}
return r.s.SetShallow(shallows)
}