mirror of https://github.com/knative/pkg.git
128 lines
2.9 KiB
Go
128 lines
2.9 KiB
Go
/*
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Copyright 2021 The Knative Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package json
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import (
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"bytes"
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"encoding/json"
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"io"
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)
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var (
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emptyMeta = []byte(`:{}`)
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metaPrefix = []byte(`{"metadata"`)
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metaSuffix = []byte(`}`)
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)
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var (
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// Unmarshal is an alias for json.Unmarshal
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Unmarshal = json.Unmarshal
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//Marshal is an alias for json.Marshal
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Marshal = json.Marshal
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)
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// Decode will parse the json byte array to the target object. When
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// unknown fields are _not_ allowed we still accept unknown
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// fields in the Object's metadata
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//
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// See https://github.com/knative/serving/issues/11448 for details
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func Decode(bites []byte, target interface{}, disallowUnknownFields bool) error {
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if !disallowUnknownFields {
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return json.Unmarshal(bites, target)
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}
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// If we don't allow unknown fields we skip validating fields in the metadata
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// block since that is opaque to us and validated by the API server
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start, end, err := findMetadataOffsets(bites)
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if err != nil {
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return err
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} else if start == -1 || end == -1 {
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// If for some reason the json does not have metadata continue with normal parsing
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dec := json.NewDecoder(bytes.NewReader(bites))
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dec.DisallowUnknownFields()
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return dec.Decode(target)
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}
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before := bites[:start]
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metadata := bites[start:end]
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after := bites[end:]
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// Parse everything but skip metadata
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dec := json.NewDecoder(io.MultiReader(
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bytes.NewReader(before),
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bytes.NewReader(emptyMeta),
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bytes.NewReader(after),
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))
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dec.DisallowUnknownFields()
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if err := dec.Decode(target); err != nil {
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return err
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}
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// Now we parse just the metadata
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dec = json.NewDecoder(io.MultiReader(
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bytes.NewReader(metaPrefix),
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bytes.NewReader(metadata),
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bytes.NewReader(metaSuffix),
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))
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return dec.Decode(target)
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}
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func findMetadataOffsets(bites []byte) (start, end int64, err error) {
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start, end = -1, -1
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level := 0
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var (
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dec = json.NewDecoder(bytes.NewReader(bites))
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t json.Token
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)
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for {
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t, err = dec.Token()
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if err == io.EOF { //nolint
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break
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}
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if err != nil {
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return
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}
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switch v := t.(type) {
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case json.Delim:
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if v == '{' {
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level++
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} else if v == '}' {
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level--
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}
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case string:
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if v == "metadata" && level == 1 {
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start = dec.InputOffset()
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x := struct{}{}
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if err = dec.Decode(&x); err != nil {
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return -1, -1, err
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}
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end = dec.InputOffset()
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// we exit early to stop processing the rest of the object
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return
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}
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}
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}
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return -1, -1, nil
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}
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