loader.go

Documentation: github.com/opencontainers/image-spec/schema

     1  // Copyright 2018 The Linux Foundation
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package schema
    16  
    17  import (
    18  	"bytes"
    19  	"encoding/json"
    20  	"fmt"
    21  	"io"
    22  	"net/http"
    23  	"strings"
    24  
    25  	"github.com/xeipuuv/gojsonreference"
    26  	"github.com/xeipuuv/gojsonschema"
    27  )
    28  
    29  // fsLoaderFactory implements gojsonschema.JSONLoaderFactory by reading files under the specified namespaces from the root of fs.
    30  type fsLoaderFactory struct {
    31  	namespaces []string
    32  	fs         http.FileSystem
    33  }
    34  
    35  // newFSLoaderFactory returns a fsLoaderFactory reading files under the specified namespaces from the root of fs.
    36  func newFSLoaderFactory(namespaces []string, fs http.FileSystem) *fsLoaderFactory {
    37  	return &fsLoaderFactory{
    38  		namespaces: namespaces,
    39  		fs:         fs,
    40  	}
    41  }
    42  
    43  func (factory *fsLoaderFactory) New(source string) gojsonschema.JSONLoader {
    44  	return &fsLoader{
    45  		factory: factory,
    46  		source:  source,
    47  	}
    48  }
    49  
    50  // refContents returns the contents of ref, if available in fsLoaderFactory.
    51  func (factory *fsLoaderFactory) refContents(ref gojsonreference.JsonReference) ([]byte, error) {
    52  	refStr := ref.String()
    53  	path := ""
    54  	for _, ns := range factory.namespaces {
    55  		if strings.HasPrefix(refStr, ns) {
    56  			path = "/" + strings.TrimPrefix(refStr, ns)
    57  			break
    58  		}
    59  	}
    60  	if path == "" {
    61  		return nil, fmt.Errorf("schema reference %#v unexpectedly not available in fsLoaderFactory with namespaces %#v", path, factory.namespaces)
    62  	}
    63  
    64  	f, err := factory.fs.Open(path)
    65  	if err != nil {
    66  		return nil, err
    67  	}
    68  	defer f.Close()
    69  
    70  	return io.ReadAll(f)
    71  }
    72  
    73  // fsLoader implements gojsonschema.JSONLoader by reading the document named by source from a fsLoaderFactory.
    74  type fsLoader struct {
    75  	factory *fsLoaderFactory
    76  	source  string
    77  }
    78  
    79  // JsonSource implements gojsonschema.JSONLoader.JsonSource. The "Json" capitalization needs to be maintained to conform to the interface.
    80  func (l *fsLoader) JsonSource() interface{} { // revive:disable-line:var-naming
    81  	return l.source
    82  }
    83  
    84  func (l *fsLoader) LoadJSON() (interface{}, error) {
    85  	// Based on gojsonschema.jsonReferenceLoader.LoadJSON.
    86  	reference, err := gojsonreference.NewJsonReference(l.source)
    87  	if err != nil {
    88  		return nil, err
    89  	}
    90  
    91  	refToURL := reference
    92  	refToURL.GetUrl().Fragment = ""
    93  
    94  	body, err := l.factory.refContents(refToURL)
    95  	if err != nil {
    96  		return nil, err
    97  	}
    98  
    99  	return decodeJSONUsingNumber(bytes.NewReader(body))
   100  }
   101  
   102  // decodeJSONUsingNumber returns JSON parsed from an io.Reader
   103  func decodeJSONUsingNumber(r io.Reader) (interface{}, error) {
   104  	// Copied from gojsonschema.
   105  	var document interface{}
   106  
   107  	decoder := json.NewDecoder(r)
   108  	decoder.UseNumber()
   109  
   110  	err := decoder.Decode(&document)
   111  	if err != nil {
   112  		return nil, err
   113  	}
   114  
   115  	return document, nil
   116  }
   117  
   118  // JsonReference implements gojsonschema.JSONLoader.JsonReference. The "Json" capitalization needs to be maintained to conform to the interface.
   119  func (l *fsLoader) JsonReference() (gojsonreference.JsonReference, error) { // revive:disable-line:var-naming
   120  	return gojsonreference.NewJsonReference(l.JsonSource().(string))
   121  }
   122  
   123  func (l *fsLoader) LoaderFactory() gojsonschema.JSONLoaderFactory {
   124  	return l.factory
   125  }
   126
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