diff options
Diffstat (limited to 'src/encoding/json/encode.go')
| -rw-r--r-- | src/encoding/json/encode.go | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/src/encoding/json/encode.go b/src/encoding/json/encode.go index 578d551102..483b9d8f2d 100644 --- a/src/encoding/json/encode.go +++ b/src/encoding/json/encode.go @@ -236,6 +236,8 @@ func (e *UnsupportedTypeError) Error() string { return "json: unsupported type: " + e.Type.String() } +// An UnsupportedValueError is returned by Marshal when attempting +// to encode an unsupported value. type UnsupportedValueError struct { Value reflect.Value Str string @@ -779,6 +781,16 @@ func (me mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { e.WriteString("null") return } + if e.ptrLevel++; e.ptrLevel > startDetectingCyclesAfter { + // We're a large number of nested ptrEncoder.encode calls deep; + // start checking if we've run into a pointer cycle. + ptr := v.Pointer() + if _, ok := e.ptrSeen[ptr]; ok { + e.error(&UnsupportedValueError{v, fmt.Sprintf("encountered a cycle via %s", v.Type())}) + } + e.ptrSeen[ptr] = struct{}{} + defer delete(e.ptrSeen, ptr) + } e.WriteByte('{') // Extract and sort the keys. @@ -801,6 +813,7 @@ func (me mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { me.elemEnc(e, v.MapIndex(kv.v), opts) } e.WriteByte('}') + e.ptrLevel-- } func newMapEncoder(t reflect.Type) encoderFunc { @@ -857,7 +870,23 @@ func (se sliceEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) { e.WriteString("null") return } + if e.ptrLevel++; e.ptrLevel > startDetectingCyclesAfter { + // We're a large number of nested ptrEncoder.encode calls deep; + // start checking if we've run into a pointer cycle. + // Here we use a struct to memorize the pointer to the first element of the slice + // and its length. + ptr := struct { + ptr uintptr + len int + }{v.Pointer(), v.Len()} + if _, ok := e.ptrSeen[ptr]; ok { + e.error(&UnsupportedValueError{v, fmt.Sprintf("encountered a cycle via %s", v.Type())}) + } + e.ptrSeen[ptr] = struct{}{} + defer delete(e.ptrSeen, ptr) + } se.arrayEnc(e, v, opts) + e.ptrLevel-- } func newSliceEncoder(t reflect.Type) encoderFunc { @@ -946,7 +975,7 @@ func isValidTag(s string) bool { } for _, c := range s { switch { - case strings.ContainsRune("!#$%&()*+-./:<=>?@[]^_{|}~ ", c): + case strings.ContainsRune("!#$%&()*+-./:;<=>?@[]^_{|}~ ", c): // Backslash and quote chars are reserved, but // otherwise any punctuation chars are allowed // in a tag name. |