prometheus/vendor/github.com/go-openapi/spec/schema_loader.go

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// Copyright 2015 go-swagger maintainers
//
// 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 spec
import (
"encoding/json"
"fmt"
"log"
"net/url"
"reflect"
"strings"
"github.com/go-openapi/swag"
)
// PathLoader function to use when loading remote refs
var PathLoader func(string) (json.RawMessage, error)
func init() {
PathLoader = func(path string) (json.RawMessage, error) {
data, err := swag.LoadFromFileOrHTTP(path)
if err != nil {
return nil, err
}
return json.RawMessage(data), nil
}
}
// resolverContext allows to share a context during spec processing.
// At the moment, it just holds the index of circular references found.
type resolverContext struct {
// circulars holds all visited circular references, which allows shortcuts.
// NOTE: this is not just a performance improvement: it is required to figure out
// circular references which participate several cycles.
// This structure is privately instantiated and needs not be locked against
// concurrent access, unless we chose to implement a parallel spec walking.
circulars map[string]bool
basePath string
}
func newResolverContext(originalBasePath string) *resolverContext {
return &resolverContext{
circulars: make(map[string]bool),
basePath: originalBasePath, // keep the root base path in context
}
}
type schemaLoader struct {
root interface{}
options *ExpandOptions
cache ResolutionCache
context *resolverContext
loadDoc func(string) (json.RawMessage, error)
}
func (r *schemaLoader) transitiveResolver(basePath string, ref Ref) (*schemaLoader, error) {
if ref.IsRoot() || ref.HasFragmentOnly {
return r, nil
}
baseRef, _ := NewRef(basePath)
currentRef := normalizeFileRef(&ref, basePath)
if strings.HasPrefix(currentRef.String(), baseRef.String()) {
return r, nil
}
// Set a new root to resolve against
rootURL := currentRef.GetURL()
rootURL.Fragment = ""
root, _ := r.cache.Get(rootURL.String())
// shallow copy of resolver options to set a new RelativeBase when
// traversing multiple documents
newOptions := r.options
newOptions.RelativeBase = rootURL.String()
debugLog("setting new root: %s", newOptions.RelativeBase)
return defaultSchemaLoader(root, newOptions, r.cache, r.context)
}
func (r *schemaLoader) updateBasePath(transitive *schemaLoader, basePath string) string {
if transitive != r {
debugLog("got a new resolver")
if transitive.options != nil && transitive.options.RelativeBase != "" {
basePath, _ = absPath(transitive.options.RelativeBase)
debugLog("new basePath = %s", basePath)
}
}
return basePath
}
func (r *schemaLoader) resolveRef(ref *Ref, target interface{}, basePath string) error {
tgt := reflect.ValueOf(target)
if tgt.Kind() != reflect.Ptr {
return fmt.Errorf("resolve ref: target needs to be a pointer")
}
refURL := ref.GetURL()
if refURL == nil {
return nil
}
var res interface{}
var data interface{}
var err error
// Resolve against the root if it isn't nil, and if ref is pointing at the root, or has a fragment only which means
// it is pointing somewhere in the root.
root := r.root
if (ref.IsRoot() || ref.HasFragmentOnly) && root == nil && basePath != "" {
if baseRef, erb := NewRef(basePath); erb == nil {
root, _, _, _ = r.load(baseRef.GetURL())
}
}
if (ref.IsRoot() || ref.HasFragmentOnly) && root != nil {
data = root
} else {
baseRef := normalizeFileRef(ref, basePath)
debugLog("current ref is: %s", ref.String())
debugLog("current ref normalized file: %s", baseRef.String())
data, _, _, err = r.load(baseRef.GetURL())
if err != nil {
return err
}
}
res = data
if ref.String() != "" {
res, _, err = ref.GetPointer().Get(data)
if err != nil {
return err
}
}
return swag.DynamicJSONToStruct(res, target)
}
func (r *schemaLoader) load(refURL *url.URL) (interface{}, url.URL, bool, error) {
debugLog("loading schema from url: %s", refURL)
toFetch := *refURL
toFetch.Fragment = ""
var err error
path := toFetch.String()
if path == rootBase {
path, err = absPath(rootBase)
if err != nil {
return nil, url.URL{}, false, err
}
}
normalized := normalizeAbsPath(path)
data, fromCache := r.cache.Get(normalized)
if !fromCache {
b, err := r.loadDoc(normalized)
if err != nil {
debugLog("unable to load the document: %v", err)
return nil, url.URL{}, false, err
}
if err := json.Unmarshal(b, &data); err != nil {
return nil, url.URL{}, false, err
}
r.cache.Set(normalized, data)
}
return data, toFetch, fromCache, nil
}
// isCircular detects cycles in sequences of $ref.
// It relies on a private context (which needs not be locked).
func (r *schemaLoader) isCircular(ref *Ref, basePath string, parentRefs ...string) (foundCycle bool) {
normalizedRef := normalizePaths(ref.String(), basePath)
if _, ok := r.context.circulars[normalizedRef]; ok {
// circular $ref has been already detected in another explored cycle
foundCycle = true
return
}
foundCycle = swag.ContainsStringsCI(parentRefs, normalizedRef)
if foundCycle {
r.context.circulars[normalizedRef] = true
}
return
}
// Resolve resolves a reference against basePath and stores the result in target
// Resolve is not in charge of following references, it only resolves ref by following its URL
// if the schema that ref is referring to has more refs in it. Resolve doesn't resolve them
// if basePath is an empty string, ref is resolved against the root schema stored in the schemaLoader struct
func (r *schemaLoader) Resolve(ref *Ref, target interface{}, basePath string) error {
return r.resolveRef(ref, target, basePath)
}
func (r *schemaLoader) deref(input interface{}, parentRefs []string, basePath string) error {
var ref *Ref
switch refable := input.(type) {
case *Schema:
ref = &refable.Ref
case *Parameter:
ref = &refable.Ref
case *Response:
ref = &refable.Ref
case *PathItem:
ref = &refable.Ref
default:
return fmt.Errorf("deref: unsupported type %T", input)
}
curRef := ref.String()
if curRef != "" {
normalizedRef := normalizeFileRef(ref, basePath)
normalizedBasePath := normalizedRef.RemoteURI()
if r.isCircular(normalizedRef, basePath, parentRefs...) {
return nil
}
if err := r.resolveRef(ref, input, basePath); r.shouldStopOnError(err) {
return err
}
// NOTE(fredbi): removed basePath check => needs more testing
if ref.String() != "" && ref.String() != curRef {
parentRefs = append(parentRefs, normalizedRef.String())
return r.deref(input, parentRefs, normalizedBasePath)
}
}
return nil
}
func (r *schemaLoader) shouldStopOnError(err error) bool {
if err != nil && !r.options.ContinueOnError {
return true
}
if err != nil {
log.Println(err)
}
return false
}
func defaultSchemaLoader(
root interface{},
expandOptions *ExpandOptions,
cache ResolutionCache,
context *resolverContext) (*schemaLoader, error) {
if cache == nil {
cache = resCache
}
if expandOptions == nil {
expandOptions = &ExpandOptions{}
}
absBase, _ := absPath(expandOptions.RelativeBase)
if context == nil {
context = newResolverContext(absBase)
}
return &schemaLoader{
root: root,
options: expandOptions,
cache: cache,
context: context,
loadDoc: func(path string) (json.RawMessage, error) {
debugLog("fetching document at %q", path)
return PathLoader(path)
},
}, nil
}