| /* |
| Copyright 2014 The Kubernetes Authors. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| */ |
| |
| package recognizer |
| |
| import ( |
| "bufio" |
| "bytes" |
| "fmt" |
| "io" |
| |
| "k8s.io/apimachinery/pkg/runtime" |
| "k8s.io/apimachinery/pkg/runtime/schema" |
| ) |
| |
| type RecognizingDecoder interface { |
| runtime.Decoder |
| // RecognizesData should return true if the input provided in the provided reader |
| // belongs to this decoder, or an error if the data could not be read or is ambiguous. |
| // Unknown is true if the data could not be determined to match the decoder type. |
| // Decoders should assume that they can read as much of peek as they need (as the caller |
| // provides) and may return unknown if the data provided is not sufficient to make a |
| // a determination. When peek returns EOF that may mean the end of the input or the |
| // end of buffered input - recognizers should return the best guess at that time. |
| RecognizesData(peek io.Reader) (ok, unknown bool, err error) |
| } |
| |
| // NewDecoder creates a decoder that will attempt multiple decoders in an order defined |
| // by: |
| // |
| // 1. The decoder implements RecognizingDecoder and identifies the data |
| // 2. All other decoders, and any decoder that returned true for unknown. |
| // |
| // The order passed to the constructor is preserved within those priorities. |
| func NewDecoder(decoders ...runtime.Decoder) runtime.Decoder { |
| return &decoder{ |
| decoders: decoders, |
| } |
| } |
| |
| type decoder struct { |
| decoders []runtime.Decoder |
| } |
| |
| var _ RecognizingDecoder = &decoder{} |
| |
| func (d *decoder) RecognizesData(peek io.Reader) (bool, bool, error) { |
| var ( |
| lastErr error |
| anyUnknown bool |
| ) |
| data, _ := bufio.NewReaderSize(peek, 1024).Peek(1024) |
| for _, r := range d.decoders { |
| switch t := r.(type) { |
| case RecognizingDecoder: |
| ok, unknown, err := t.RecognizesData(bytes.NewBuffer(data)) |
| if err != nil { |
| lastErr = err |
| continue |
| } |
| anyUnknown = anyUnknown || unknown |
| if !ok { |
| continue |
| } |
| return true, false, nil |
| } |
| } |
| return false, anyUnknown, lastErr |
| } |
| |
| func (d *decoder) Decode(data []byte, gvk *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) { |
| var ( |
| lastErr error |
| skipped []runtime.Decoder |
| ) |
| |
| // try recognizers, record any decoders we need to give a chance later |
| for _, r := range d.decoders { |
| switch t := r.(type) { |
| case RecognizingDecoder: |
| buf := bytes.NewBuffer(data) |
| ok, unknown, err := t.RecognizesData(buf) |
| if err != nil { |
| lastErr = err |
| continue |
| } |
| if unknown { |
| skipped = append(skipped, t) |
| continue |
| } |
| if !ok { |
| continue |
| } |
| return r.Decode(data, gvk, into) |
| default: |
| skipped = append(skipped, t) |
| } |
| } |
| |
| // try recognizers that returned unknown or didn't recognize their data |
| for _, r := range skipped { |
| out, actual, err := r.Decode(data, gvk, into) |
| if err != nil { |
| lastErr = err |
| continue |
| } |
| return out, actual, nil |
| } |
| |
| if lastErr == nil { |
| lastErr = fmt.Errorf("no serialization format matched the provided data") |
| } |
| return nil, nil, lastErr |
| } |