// generateSnapshot generates a new snapshot from the previous one in the store - this assumes all
// the other roles except timestamp have already been set on the repo, and will set the generated
// snapshot on the repo as well
func generateSnapshot(gun string, builder tuf.RepoBuilder, store storage.MetaStore) (*storage.MetaUpdate, error) {
var prev *data.SignedSnapshot
_, currentJSON, err := store.GetCurrent(gun, data.CanonicalSnapshotRole)
if err == nil {
prev = new(data.SignedSnapshot)
if err = json.Unmarshal(currentJSON, prev); err != nil {
logrus.Error("Failed to unmarshal existing snapshot for GUN ", gun)
return nil, err
}
}
if _, ok := err.(storage.ErrNotFound); !ok && err != nil {
return nil, err
}
meta, ver, err := builder.GenerateSnapshot(prev)
switch err.(type) {
case nil:
return &storage.MetaUpdate{
Role: data.CanonicalSnapshotRole,
Version: ver,
Data: meta,
}, nil
case signed.ErrInsufficientSignatures, signed.ErrNoKeys, signed.ErrRoleThreshold:
// If we cannot sign the snapshot, then we don't have keys for the snapshot,
// and the client should have submitted a snapshot
return nil, validation.ErrBadHierarchy{
Missing: data.CanonicalSnapshotRole,
Msg: "no snapshot was included in update and server does not hold current snapshot key for repository"}
default:
return nil, validation.ErrValidation{Msg: err.Error()}
}
}
