package jsonpatch import ( "bytes" "encoding/json" "fmt" "strconv" "strings" "github.com/pkg/errors" ) const ( eRaw = iota eDoc eAry ) var ( // SupportNegativeIndices decides whether to support non-standard practice of // allowing negative indices to mean indices starting at the end of an array. // Default to true. SupportNegativeIndices bool = true // AccumulatedCopySizeLimit limits the total size increase in bytes caused by // "copy" operations in a patch. AccumulatedCopySizeLimit int64 = 0 startObject = json.Delim('{') endObject = json.Delim('}') startArray = json.Delim('[') endArray = json.Delim(']') ) var ( ErrTestFailed = errors.New("test failed") ErrMissing = errors.New("missing value") ErrUnknownType = errors.New("unknown object type") ErrInvalid = errors.New("invalid state detected") ErrInvalidIndex = errors.New("invalid index referenced") rawJSONArray = []byte("[]") rawJSONObject = []byte("{}") rawJSONNull = []byte("null") ) type lazyNode struct { raw *json.RawMessage doc *partialDoc ary partialArray which int } // Operation is a single JSON-Patch step, such as a single 'add' operation. type Operation map[string]*json.RawMessage // Patch is an ordered collection of Operations. type Patch []Operation type partialDoc struct { keys []string obj map[string]*lazyNode } type partialArray []*lazyNode type container interface { get(key string, options *ApplyOptions) (*lazyNode, error) set(key string, val *lazyNode, options *ApplyOptions) error add(key string, val *lazyNode, options *ApplyOptions) error remove(key string, options *ApplyOptions) error } // ApplyOptions specifies options for calls to ApplyWithOptions. // Use NewApplyOptions to obtain default values for ApplyOptions. type ApplyOptions struct { // SupportNegativeIndices decides whether to support non-standard practice of // allowing negative indices to mean indices starting at the end of an array. // Default to true. SupportNegativeIndices bool // AccumulatedCopySizeLimit limits the total size increase in bytes caused by // "copy" operations in a patch. AccumulatedCopySizeLimit int64 // AllowMissingPathOnRemove indicates whether to fail "remove" operations when the target path is missing. // Default to false. AllowMissingPathOnRemove bool // EnsurePathExistsOnAdd instructs json-patch to recursively create the missing parts of path on "add" operation. // Default to false. EnsurePathExistsOnAdd bool } // NewApplyOptions creates a default set of options for calls to ApplyWithOptions. func NewApplyOptions() *ApplyOptions { return &ApplyOptions{ SupportNegativeIndices: SupportNegativeIndices, AccumulatedCopySizeLimit: AccumulatedCopySizeLimit, AllowMissingPathOnRemove: false, EnsurePathExistsOnAdd: false, } } func newLazyNode(raw *json.RawMessage) *lazyNode { return &lazyNode{raw: raw, doc: nil, ary: nil, which: eRaw} } func newRawMessage(buf []byte) *json.RawMessage { ra := make(json.RawMessage, len(buf)) copy(ra, buf) return &ra } func (n *lazyNode) MarshalJSON() ([]byte, error) { switch n.which { case eRaw: return json.Marshal(n.raw) case eDoc: return json.Marshal(n.doc) case eAry: return json.Marshal(n.ary) default: return nil, ErrUnknownType } } func (n *lazyNode) UnmarshalJSON(data []byte) error { dest := make(json.RawMessage, len(data)) copy(dest, data) n.raw = &dest n.which = eRaw return nil } func (n *partialDoc) MarshalJSON() ([]byte, error) { var buf bytes.Buffer if _, err := buf.WriteString("{"); err != nil { return nil, err } for i, k := range n.keys { if i > 0 { if _, err := buf.WriteString(", "); err != nil { return nil, err } } key, err := json.Marshal(k) if err != nil { return nil, err } if _, err := buf.Write(key); err != nil { return nil, err } if _, err := buf.WriteString(": "); err != nil { return nil, err } value, err := json.Marshal(n.obj[k]) if err != nil { return nil, err } if _, err := buf.Write(value); err != nil { return nil, err } } if _, err := buf.WriteString("}"); err != nil { return nil, err } return buf.Bytes(), nil } type syntaxError struct { msg string } func (err *syntaxError) Error() string { return err.msg } func (n *partialDoc) UnmarshalJSON(data []byte) error { if err := json.Unmarshal(data, &n.obj); err != nil { return err } buffer := bytes.NewBuffer(data) d := json.NewDecoder(buffer) if t, err := d.Token(); err != nil { return err } else if t != startObject { return &syntaxError{fmt.Sprintf("unexpected JSON token in document node: %s", t)} } for d.More() { k, err := d.Token() if err != nil { return err } key, ok := k.(string) if !ok { return &syntaxError{fmt.Sprintf("unexpected JSON token as document node key: %s", k)} } if err := skipValue(d); err != nil { return err } n.keys = append(n.keys, key) } return nil } func skipValue(d *json.Decoder) error { t, err := d.Token() if err != nil { return err } if t != startObject && t != startArray { return nil } for d.More() { if t == startObject { // consume key token if _, err := d.Token(); err != nil { return err } } if err := skipValue(d); err != nil { return err } } end, err := d.Token() if err != nil { return err } if t == startObject && end != endObject { return &syntaxError{msg: "expected close object token"} } if t == startArray && end != endArray { return &syntaxError{msg: "expected close object token"} } return nil } func deepCopy(src *lazyNode) (*lazyNode, int, error) { if src == nil { return nil, 0, nil } a, err := src.MarshalJSON() if err != nil { return nil, 0, err } sz := len(a) return newLazyNode(newRawMessage(a)), sz, nil } func (n *lazyNode) intoDoc() (*partialDoc, error) { if n.which == eDoc { return n.doc, nil } if n.raw == nil { return nil, ErrInvalid } err := json.Unmarshal(*n.raw, &n.doc) if err != nil { return nil, err } n.which = eDoc return n.doc, nil } func (n *lazyNode) intoAry() (*partialArray, error) { if n.which == eAry { return &n.ary, nil } if n.raw == nil { return nil, ErrInvalid } err := json.Unmarshal(*n.raw, &n.ary) if err != nil { return nil, err } n.which = eAry return &n.ary, nil } func (n *lazyNode) compact() []byte { buf := &bytes.Buffer{} if n.raw == nil { return nil } err := json.Compact(buf, *n.raw) if err != nil { return *n.raw } return buf.Bytes() } func (n *lazyNode) tryDoc() bool { if n.raw == nil { return false } err := json.Unmarshal(*n.raw, &n.doc) if err != nil { return false } n.which = eDoc return true } func (n *lazyNode) tryAry() bool { if n.raw == nil { return false } err := json.Unmarshal(*n.raw, &n.ary) if err != nil { return false } n.which = eAry return true } func (n *lazyNode) equal(o *lazyNode) bool { if n.which == eRaw { if !n.tryDoc() && !n.tryAry() { if o.which != eRaw { return false } return bytes.Equal(n.compact(), o.compact()) } } if n.which == eDoc { if o.which == eRaw { if !o.tryDoc() { return false } } if o.which != eDoc { return false } if len(n.doc.obj) != len(o.doc.obj) { return false } for k, v := range n.doc.obj { ov, ok := o.doc.obj[k] if !ok { return false } if (v == nil) != (ov == nil) { return false } if v == nil && ov == nil { continue } if !v.equal(ov) { return false } } return true } if o.which != eAry && !o.tryAry() { return false } if len(n.ary) != len(o.ary) { return false } for idx, val := range n.ary { if !val.equal(o.ary[idx]) { return false } } return true } // Kind reads the "op" field of the Operation. func (o Operation) Kind() string { if obj, ok := o["op"]; ok && obj != nil { var op string err := json.Unmarshal(*obj, &op) if err != nil { return "unknown" } return op } return "unknown" } // Path reads the "path" field of the Operation. func (o Operation) Path() (string, error) { if obj, ok := o["path"]; ok && obj != nil { var op string err := json.Unmarshal(*obj, &op) if err != nil { return "unknown", err } return op, nil } return "unknown", errors.Wrapf(ErrMissing, "operation missing path field") } // From reads the "from" field of the Operation. func (o Operation) From() (string, error) { if obj, ok := o["from"]; ok && obj != nil { var op string err := json.Unmarshal(*obj, &op) if err != nil { return "unknown", err } return op, nil } return "unknown", errors.Wrapf(ErrMissing, "operation, missing from field") } func (o Operation) value() *lazyNode { if obj, ok := o["value"]; ok { return newLazyNode(obj) } return nil } // ValueInterface decodes the operation value into an interface. func (o Operation) ValueInterface() (interface{}, error) { if obj, ok := o["value"]; ok && obj != nil { var v interface{} err := json.Unmarshal(*obj, &v) if err != nil { return nil, err } return v, nil } return nil, errors.Wrapf(ErrMissing, "operation, missing value field") } func isArray(buf []byte) bool { Loop: for _, c := range buf { switch c { case ' ': case '\n': case '\t': continue case '[': return true default: break Loop } } return false } func findObject(pd *container, path string, options *ApplyOptions) (container, string) { doc := *pd split := strings.Split(path, "/") if len(split) < 2 { return nil, "" } parts := split[1 : len(split)-1] key := split[len(split)-1] var err error for _, part := range parts { next, ok := doc.get(decodePatchKey(part), options) if next == nil || ok != nil { return nil, "" } if isArray(*next.raw) { doc, err = next.intoAry() if err != nil { return nil, "" } } else { doc, err = next.intoDoc() if err != nil { return nil, "" } } } return doc, decodePatchKey(key) } func (d *partialDoc) set(key string, val *lazyNode, options *ApplyOptions) error { found := false for _, k := range d.keys { if k == key { found = true break } } if !found { d.keys = append(d.keys, key) } d.obj[key] = val return nil } func (d *partialDoc) add(key string, val *lazyNode, options *ApplyOptions) error { return d.set(key, val, options) } func (d *partialDoc) get(key string, options *ApplyOptions) (*lazyNode, error) { v, ok := d.obj[key] if !ok { return v, errors.Wrapf(ErrMissing, "unable to get nonexistent key: %s", key) } return v, nil } func (d *partialDoc) remove(key string, options *ApplyOptions) error { _, ok := d.obj[key] if !ok { if options.AllowMissingPathOnRemove { return nil } return errors.Wrapf(ErrMissing, "unable to remove nonexistent key: %s", key) } idx := -1 for i, k := range d.keys { if k == key { idx = i break } } d.keys = append(d.keys[0:idx], d.keys[idx+1:]...) delete(d.obj, key) return nil } // set should only be used to implement the "replace" operation, so "key" must // be an already existing index in "d". func (d *partialArray) set(key string, val *lazyNode, options *ApplyOptions) error { idx, err := strconv.Atoi(key) if err != nil { return err } if idx < 0 { if !options.SupportNegativeIndices { return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } if idx < -len(*d) { return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } idx += len(*d) } (*d)[idx] = val return nil } func (d *partialArray) add(key string, val *lazyNode, options *ApplyOptions) error { if key == "-" { *d = append(*d, val) return nil } idx, err := strconv.Atoi(key) if err != nil { return errors.Wrapf(err, "value was not a proper array index: '%s'", key) } sz := len(*d) + 1 ary := make([]*lazyNode, sz) cur := *d if idx >= len(ary) { return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } if idx < 0 { if !options.SupportNegativeIndices { return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } if idx < -len(ary) { return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } idx += len(ary) } copy(ary[0:idx], cur[0:idx]) ary[idx] = val copy(ary[idx+1:], cur[idx:]) *d = ary return nil } func (d *partialArray) get(key string, options *ApplyOptions) (*lazyNode, error) { idx, err := strconv.Atoi(key) if err != nil { return nil, err } if idx < 0 { if !options.SupportNegativeIndices { return nil, errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } if idx < -len(*d) { return nil, errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } idx += len(*d) } if idx >= len(*d) { return nil, errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } return (*d)[idx], nil } func (d *partialArray) remove(key string, options *ApplyOptions) error { idx, err := strconv.Atoi(key) if err != nil { return err } cur := *d if idx >= len(cur) { if options.AllowMissingPathOnRemove { return nil } return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } if idx < 0 { if !options.SupportNegativeIndices { return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } if idx < -len(cur) { if options.AllowMissingPathOnRemove { return nil } return errors.Wrapf(ErrInvalidIndex, "Unable to access invalid index: %d", idx) } idx += len(cur) } ary := make([]*lazyNode, len(cur)-1) copy(ary[0:idx], cur[0:idx]) copy(ary[idx:], cur[idx+1:]) *d = ary return nil } func (p Patch) add(doc *container, op Operation, options *ApplyOptions) error { path, err := op.Path() if err != nil { return errors.Wrapf(ErrMissing, "add operation failed to decode path") } if options.EnsurePathExistsOnAdd { err = ensurePathExists(doc, path, options) if err != nil { return err } } con, key := findObject(doc, path, options) if con == nil { return errors.Wrapf(ErrMissing, "add operation does not apply: doc is missing path: \"%s\"", path) } err = con.add(key, op.value(), options) if err != nil { return errors.Wrapf(err, "error in add for path: '%s'", path) } return nil } // Given a document and a path to a key, walk the path and create all missing elements // creating objects and arrays as needed. func ensurePathExists(pd *container, path string, options *ApplyOptions) error { doc := *pd var err error var arrIndex int split := strings.Split(path, "/") if len(split) < 2 { return nil } parts := split[1:] for pi, part := range parts { // Have we reached the key part of the path? // If yes, we're done. if pi == len(parts)-1 { return nil } target, ok := doc.get(decodePatchKey(part), options) if target == nil || ok != nil { // If the current container is an array which has fewer elements than our target index, // pad the current container with nulls. if arrIndex, err = strconv.Atoi(part); err == nil { pa, ok := doc.(*partialArray) if ok && arrIndex >= len(*pa)+1 { // Pad the array with null values up to the required index. for i := len(*pa); i <= arrIndex-1; i++ { doc.add(strconv.Itoa(i), newLazyNode(newRawMessage(rawJSONNull)), options) } } } // Check if the next part is a numeric index or "-". // If yes, then create an array, otherwise, create an object. if arrIndex, err = strconv.Atoi(parts[pi+1]); err == nil || parts[pi+1] == "-" { if arrIndex < 0 { if !options.SupportNegativeIndices { return errors.Wrapf(ErrInvalidIndex, "Unable to ensure path for invalid index: %d", arrIndex) } if arrIndex < -1 { return errors.Wrapf(ErrInvalidIndex, "Unable to ensure path for negative index other than -1: %d", arrIndex) } arrIndex = 0 } newNode := newLazyNode(newRawMessage(rawJSONArray)) doc.add(part, newNode, options) doc, _ = newNode.intoAry() // Pad the new array with null values up to the required index. for i := 0; i < arrIndex; i++ { doc.add(strconv.Itoa(i), newLazyNode(newRawMessage(rawJSONNull)), options) } } else { newNode := newLazyNode(newRawMessage(rawJSONObject)) doc.add(part, newNode, options) doc, _ = newNode.intoDoc() } } else { if isArray(*target.raw) { doc, err = target.intoAry() if err != nil { return err } } else { doc, err = target.intoDoc() if err != nil { return err } } } } return nil } func (p Patch) remove(doc *container, op Operation, options *ApplyOptions) error { path, err := op.Path() if err != nil { return errors.Wrapf(ErrMissing, "remove operation failed to decode path") } con, key := findObject(doc, path, options) if con == nil { if options.AllowMissingPathOnRemove { return nil } return errors.Wrapf(ErrMissing, "remove operation does not apply: doc is missing path: \"%s\"", path) } err = con.remove(key, options) if err != nil { return errors.Wrapf(err, "error in remove for path: '%s'", path) } return nil } func (p Patch) replace(doc *container, op Operation, options *ApplyOptions) error { path, err := op.Path() if err != nil { return errors.Wrapf(err, "replace operation failed to decode path") } if path == "" { val := op.value() if val.which == eRaw { if !val.tryDoc() { if !val.tryAry() { return errors.Wrapf(err, "replace operation value must be object or array") } } } switch val.which { case eAry: *doc = &val.ary case eDoc: *doc = val.doc case eRaw: return errors.Wrapf(err, "replace operation hit impossible case") } return nil } con, key := findObject(doc, path, options) if con == nil { return errors.Wrapf(ErrMissing, "replace operation does not apply: doc is missing path: %s", path) } _, ok := con.get(key, options) if ok != nil { return errors.Wrapf(ErrMissing, "replace operation does not apply: doc is missing key: %s", path) } err = con.set(key, op.value(), options) if err != nil { return errors.Wrapf(err, "error in remove for path: '%s'", path) } return nil } func (p Patch) move(doc *container, op Operation, options *ApplyOptions) error { from, err := op.From() if err != nil { return errors.Wrapf(err, "move operation failed to decode from") } con, key := findObject(doc, from, options) if con == nil { return errors.Wrapf(ErrMissing, "move operation does not apply: doc is missing from path: %s", from) } val, err := con.get(key, options) if err != nil { return errors.Wrapf(err, "error in move for path: '%s'", key) } err = con.remove(key, options) if err != nil { return errors.Wrapf(err, "error in move for path: '%s'", key) } path, err := op.Path() if err != nil { return errors.Wrapf(err, "move operation failed to decode path") } con, key = findObject(doc, path, options) if con == nil { return errors.Wrapf(ErrMissing, "move operation does not apply: doc is missing destination path: %s", path) } err = con.add(key, val, options) if err != nil { return errors.Wrapf(err, "error in move for path: '%s'", path) } return nil } func (p Patch) test(doc *container, op Operation, options *ApplyOptions) error { path, err := op.Path() if err != nil { return errors.Wrapf(err, "test operation failed to decode path") } if path == "" { var self lazyNode switch sv := (*doc).(type) { case *partialDoc: self.doc = sv self.which = eDoc case *partialArray: self.ary = *sv self.which = eAry } if self.equal(op.value()) { return nil } return errors.Wrapf(ErrTestFailed, "testing value %s failed", path) } con, key := findObject(doc, path, options) if con == nil { return errors.Wrapf(ErrMissing, "test operation does not apply: is missing path: %s", path) } val, err := con.get(key, options) if err != nil && errors.Cause(err) != ErrMissing { return errors.Wrapf(err, "error in test for path: '%s'", path) } if val == nil { if op.value().raw == nil { return nil } return errors.Wrapf(ErrTestFailed, "testing value %s failed", path) } else if op.value() == nil { return errors.Wrapf(ErrTestFailed, "testing value %s failed", path) } if val.equal(op.value()) { return nil } return errors.Wrapf(ErrTestFailed, "testing value %s failed", path) } func (p Patch) copy(doc *container, op Operation, accumulatedCopySize *int64, options *ApplyOptions) error { from, err := op.From() if err != nil { return errors.Wrapf(err, "copy operation failed to decode from") } con, key := findObject(doc, from, options) if con == nil { return errors.Wrapf(ErrMissing, "copy operation does not apply: doc is missing from path: %s", from) } val, err := con.get(key, options) if err != nil { return errors.Wrapf(err, "error in copy for from: '%s'", from) } path, err := op.Path() if err != nil { return errors.Wrapf(ErrMissing, "copy operation failed to decode path") } con, key = findObject(doc, path, options) if con == nil { return errors.Wrapf(ErrMissing, "copy operation does not apply: doc is missing destination path: %s", path) } valCopy, sz, err := deepCopy(val) if err != nil { return errors.Wrapf(err, "error while performing deep copy") } (*accumulatedCopySize) += int64(sz) if options.AccumulatedCopySizeLimit > 0 && *accumulatedCopySize > options.AccumulatedCopySizeLimit { return NewAccumulatedCopySizeError(options.AccumulatedCopySizeLimit, *accumulatedCopySize) } err = con.add(key, valCopy, options) if err != nil { return errors.Wrapf(err, "error while adding value during copy") } return nil } // Equal indicates if 2 JSON documents have the same structural equality. func Equal(a, b []byte) bool { la := newLazyNode(newRawMessage(a)) lb := newLazyNode(newRawMessage(b)) return la.equal(lb) } // DecodePatch decodes the passed JSON document as an RFC 6902 patch. func DecodePatch(buf []byte) (Patch, error) { var p Patch err := json.Unmarshal(buf, &p) if err != nil { return nil, err } return p, nil } // Apply mutates a JSON document according to the patch, and returns the new // document. func (p Patch) Apply(doc []byte) ([]byte, error) { return p.ApplyWithOptions(doc, NewApplyOptions()) } // ApplyWithOptions mutates a JSON document according to the patch and the passed in ApplyOptions. // It returns the new document. func (p Patch) ApplyWithOptions(doc []byte, options *ApplyOptions) ([]byte, error) { return p.ApplyIndentWithOptions(doc, "", options) } // ApplyIndent mutates a JSON document according to the patch, and returns the new // document indented. func (p Patch) ApplyIndent(doc []byte, indent string) ([]byte, error) { return p.ApplyIndentWithOptions(doc, indent, NewApplyOptions()) } // ApplyIndentWithOptions mutates a JSON document according to the patch and the passed in ApplyOptions. // It returns the new document indented. func (p Patch) ApplyIndentWithOptions(doc []byte, indent string, options *ApplyOptions) ([]byte, error) { if len(doc) == 0 { return doc, nil } var pd container if doc[0] == '[' { pd = &partialArray{} } else { pd = &partialDoc{} } err := json.Unmarshal(doc, pd) if err != nil { return nil, err } err = nil var accumulatedCopySize int64 for _, op := range p { switch op.Kind() { case "add": err = p.add(&pd, op, options) case "remove": err = p.remove(&pd, op, options) case "replace": err = p.replace(&pd, op, options) case "move": err = p.move(&pd, op, options) case "test": err = p.test(&pd, op, options) case "copy": err = p.copy(&pd, op, &accumulatedCopySize, options) default: err = fmt.Errorf("Unexpected kind: %s", op.Kind()) } if err != nil { return nil, err } } if indent != "" { return json.MarshalIndent(pd, "", indent) } return json.Marshal(pd) } // From http://tools.ietf.org/html/rfc6901#section-4 : // // Evaluation of each reference token begins by decoding any escaped // character sequence. This is performed by first transforming any // occurrence of the sequence '~1' to '/', and then transforming any // occurrence of the sequence '~0' to '~'. var ( rfc6901Decoder = strings.NewReplacer("~1", "/", "~0", "~") ) func decodePatchKey(k string) string { return rfc6901Decoder.Replace(k) }