// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Delete the next line to include in the gob package.
// +build ignore
package gob
// This file is not normally included in the gob package. Used only for debugging the package itself.
// Except for reading uints, it is an implementation of a reader that is independent of
// the one implemented by Decoder.
// To enable the Debug function, delete the +build ignore line above and do
// go install
import (
"bytes"
"fmt"
"io"
"os"
"strings"
"sync"
)
var dumpBytes = false // If true, print the remaining bytes in the input buffer at each item.
// Init installs the debugging facility. If this file is not compiled in the
// package, the tests in codec_test.go are no-ops.
func init() {
debugFunc = Debug
}
var (
blanks = bytes.Repeat([]byte{' '}, 3*10)
empty = []byte(": <empty>\n")
tabs = strings.Repeat("\t", 100)
)
// tab indents itself when printed.
type tab int
func (t tab) String() string {
n := int(t)
if n > len(tabs) {
n = len(tabs)
}
return tabs[0:n]
}
func (t tab) print() {
fmt.Fprint(os.Stderr, t)
}
// A peekReader wraps an io.Reader, allowing one to peek ahead to see
// what's coming without stealing the data from the client of the Reader.
type peekReader struct {
r io.Reader
data []byte // read-ahead data
}
// newPeekReader returns a peekReader that wraps r.
func newPeekReader(r io.Reader) *peekReader {
return &peekReader{r: r}
}
// Read is the usual method. It will first take data that has been read ahead.
func (p *peekReader) Read(b []byte) (n int, err error) {
if len(p.data) == 0 {
return p.r.Read(b)
}
// Satisfy what's possible from the read-ahead data.
n = copy(b, p.data)
// Move data down to beginning of slice, to avoid endless growth
copy(p.data, p.data[n:])
p.data = p.data[:len(p.data)-n]
return
}
// peek returns as many bytes as possible from the unread
// portion of the stream, up to the length of b.
func (p *peekReader) peek(b []byte) (n int, err error) {
if len(p.data) > 0 {
n = copy(b, p.data)
if n == len(b) {
return
}
b = b[n:]
}
if len(b) == 0 {
return
}
m, e := io.ReadFull(p.r, b)
if m > 0 {
p.data = append(p.data, b[:m]...)
}
n += m
if e == io.ErrUnexpectedEOF {
// That means m > 0 but we reached EOF. If we got data
// we won't complain about not being able to peek enough.
if n > 0 {
e = nil
} else {
e = io.EOF
}
}
return n, e
}
type debugger struct {
mutex sync.Mutex
remain int // the number of bytes known to remain in the input
remainingKnown bool // the value of 'remain' is valid
r *peekReader
wireType map[typeId]*wireType
tmp []byte // scratch space for decoding uints.
}
// dump prints the next nBytes of the input.
// It arranges to print the output aligned from call to
// call, to make it easy to see what has been consumed.
func (deb *debugger) dump(format string, args ...interface{}) {
if !dumpBytes {
return
}
fmt.Fprintf(os.Stderr, format+" ", args...)
if !deb.remainingKnown {
return
}
if deb.remain < 0 {
fmt.Fprintf(os.Stderr, "remaining byte count is negative! %d\n", deb.remain)
return
}
data := make([]byte, deb.remain)
n, _ := deb.r.peek(data)
if n == 0 {
os.Stderr.Write(empty)
return
}
b := new(bytes.Buffer)
fmt.Fprintf(b, "[%d]{\n", deb.remain)
// Blanks until first byte
lineLength := 0
if n := len(data); n%10 != 0 {
lineLength = 10 - n%10
fmt.Fprintf(b, "\t%s", blanks[:lineLength*3])
}
// 10 bytes per line
for len(data) > 0 {
if lineLength == 0 {
fmt.Fprint(b, "\t")
}
m := 10 - lineLength
lineLength = 0
if m > len(data) {
m = len(data)
}
fmt.Fprintf(b, "% x\n", data[:m])
data = data[m:]
}
fmt.Fprint(b, "}\n")
os.Stderr.Write(b.Bytes())
}
// Debug prints a human-readable representation of the gob data read from r.
// It is a no-op unless debugging was enabled when the package was built.
func Debug(r io.Reader) {
err := debug(r)
if err != nil {
fmt.Fprintf(os.Stderr, "gob debug: %s\n", err)
}
}
// debug implements Debug, but catches panics and returns
// them as errors to be printed by Debug.
func debug(r io.Reader) (err error) {
defer catchError(&err)
fmt.Fprintln(os.Stderr, "Start of debugging")
deb := &debugger{
r: newPeekReader(r),
wireType: make(map[typeId]*wireType),
tmp: make([]byte, 16),
}
if b, ok := r.(*bytes.Buffer); ok {
deb.remain = b.Len()
deb.remainingKnown = true
}
deb.gobStream()
return
}
// note that we've consumed some bytes
func (deb *debugger) consumed(n int) {
if deb.remainingKnown {
deb.remain -= n
}
}
// int64 decodes and returns the next integer, which must be present.
// Don't call this if you could be at EOF.
func (deb *debugger) int64() int64 {
return toInt(deb.uint64())
}
// uint64 returns and decodes the next unsigned integer, which must be present.
// Don't call this if you could be at EOF.
// TODO: handle errors better.
func (deb *debugger) uint64() uint64 {
n, w, err := decodeUintReader(deb.r, deb.tmp)
if err != nil {
errorf("debug: read error: %s", err)
}
deb.consumed(w)
return n
}
// GobStream:
// DelimitedMessage* (until EOF)
func (deb *debugger) gobStream() {
// Make sure we're single-threaded through here.
deb.mutex.Lock()
defer deb.mutex.Unlock()
for deb.delimitedMessage(0) {
}
}
// DelimitedMessage:
// uint(lengthOfMessage) Message
func (deb *debugger) delimitedMessage(indent tab) bool {
for {
n := deb.loadBlock(true)
if n < 0 {
return false
}
deb.dump("Delimited message of length %d", n)
deb.message(indent)
}
return true
}
// loadBlock preps us to read a message
// of the length specified next in the input. It returns
// the length of the block. The argument tells whether
// an EOF is acceptable now. If it is and one is found,
// the return value is negative.
func (deb *debugger) loadBlock(eofOK bool) int {
n64, w, err := decodeUintReader(deb.r, deb.tmp) // deb.uint64 will error at EOF
if err != nil {
if eofOK && err == io.EOF {
return -1
}
errorf("debug: unexpected error: %s", err)
}
deb.consumed(w)
n := int(n64)
if n < 0 {
errorf("huge value for message length: %d", n64)
}
return int(n)
}
// Message:
// TypeSequence TypedValue
// TypeSequence
// (TypeDefinition DelimitedTypeDefinition*)?
// DelimitedTypeDefinition:
// uint(lengthOfTypeDefinition) TypeDefinition
// TypedValue:
// int(typeId) Value
func (deb *debugger) message(indent tab) bool {
for {
// Convert the uint64 to a signed integer typeId
uid := deb.int64()
id := typeId(uid)
deb.dump("type id=%d", id)
if id < 0 {
deb.typeDefinition(indent, -id)
n := deb.loadBlock(false)
deb.dump("Message of length %d", n)
continue
} else {
deb.value(indent, id)
break
}
}
return true
}
// Helper methods to make it easy to scan a type descriptor.
// common returns the CommonType at the input point.
func (deb *debugger) common() CommonType {
fieldNum := -1
name := ""
id := typeId(0)
for {
delta := deb.delta(-1)
if delta == 0 {
break
}
fieldNum += delta
switch fieldNum {
case 0:
name = deb.string()
case 1:
// Id typeId
id = deb.typeId()
default:
errorf("corrupted CommonType, delta is %d fieldNum is %d", delta, fieldNum)
}
}
return CommonType{name, id}
}
// uint returns the unsigned int at the input point, as a uint (not uint64).
func (deb *debugger) uint() uint {
return uint(deb.uint64())
}
// int returns the signed int at the input point, as an int (not int64).
func (deb *debugger) int() int {
return int(deb.int64())
}
// typeId returns the type id at the input point.
func (deb *debugger) typeId() typeId {
return typeId(deb.int64())
}
// string returns the string at the input point.
func (deb *debugger) string() string {
x := int(deb.uint64())
b := make([]byte, x)
nb, _ := deb.r.Read(b)
if nb != x {
errorf("corrupted type")
}
deb.consumed(nb)
return string(b)
}
// delta returns the field delta at the input point. The expect argument,
// if non-negative, identifies what the value should be.
func (deb *debugger) delta(expect int) int {
delta := int(deb.uint64())
if delta < 0 || (expect >= 0 && delta != expect) {
errorf("decode: corrupted type: delta %d expected %d", delta, expect)
}
return delta
}
// TypeDefinition:
// [int(-typeId) (already read)] encodingOfWireType
func (deb *debugger) typeDefinition(indent tab, id typeId) {
deb.dump("type definition for id %d", id)
// Encoding is of a wireType. Decode the structure as usual
fieldNum := -1
wire := new(wireType)
// A wireType defines a single field.
delta := deb.delta(-1)
fieldNum += delta
switch fieldNum {
case 0: // array type, one field of {{Common}, elem, length}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
// Field number 1 is type Id of elem
deb.delta(1)
id := deb.typeId()
// Field number 3 is length
deb.delta(1)
length := deb.int()
wire.ArrayT = &arrayType{com, id, length}
case 1: // slice type, one field of {{Common}, elem}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
// Field number 1 is type Id of elem
deb.delta(1)
id := deb.typeId()
wire.SliceT = &sliceType{com, id}
case 2: // struct type, one field of {{Common}, []fieldType}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
// Field number 1 is slice of FieldType
deb.delta(1)
numField := int(deb.uint())
field := make([]*fieldType, numField)
for i := 0; i < numField; i++ {
field[i] = new(fieldType)
deb.delta(1) // field 0 of fieldType: name
field[i].Name = deb.string()
deb.delta(1) // field 1 of fieldType: id
field[i].Id = deb.typeId()
deb.delta(0) // end of fieldType
}
wire.StructT = &structType{com, field}
case 3: // map type, one field of {{Common}, key, elem}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
// Field number 1 is type Id of key
deb.delta(1)
keyId := deb.typeId()
// Field number 2 is type Id of elem
deb.delta(1)
elemId := deb.typeId()
wire.MapT = &mapType{com, keyId, elemId}
case 4: // GobEncoder type, one field of {{Common}}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
wire.GobEncoderT = &gobEncoderType{com}
case 5: // BinaryMarshaler type, one field of {{Common}}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
wire.BinaryMarshalerT = &gobEncoderType{com}
case 6: // TextMarshaler type, one field of {{Common}}
// Field number 0 is CommonType
deb.delta(1)
com := deb.common()
wire.TextMarshalerT = &gobEncoderType{com}
default:
errorf("bad field in type %d", fieldNum)
}
deb.printWireType(indent, wire)
deb.delta(0) // end inner type (arrayType, etc.)
deb.delta(0) // end wireType
// Remember we've seen this type.
deb.wireType[id] = wire
}
// Value:
// SingletonValue | StructValue
func (deb *debugger) value(indent tab, id typeId) {
wire, ok := deb.wireType[id]
if ok && wire.StructT != nil {
deb.structValue(indent, id)
} else {
deb.singletonValue(indent, id)
}
}
// SingletonValue:
// uint(0) FieldValue
func (deb *debugger) singletonValue(indent tab, id typeId) {
deb.dump("Singleton value")
// is it a builtin type?
wire := deb.wireType[id]
_, ok := builtinIdToType[id]
if !ok && wire == nil {
errorf("type id %d not defined", id)
}
m := deb.uint64()
if m != 0 {
errorf("expected zero; got %d", m)
}
deb.fieldValue(indent, id)
}
// InterfaceValue:
// NilInterfaceValue | NonNilInterfaceValue
func (deb *debugger) interfaceValue(indent tab) {
deb.dump("Start of interface value")
if nameLen := deb.uint64(); nameLen == 0 {
deb.nilInterfaceValue(indent)
} else {
deb.nonNilInterfaceValue(indent, int(nameLen))
}
}
// NilInterfaceValue:
// uint(0) [already read]
func (deb *debugger) nilInterfaceValue(indent tab) int {
fmt.Fprintf(os.Stderr, "%snil interface\n", indent)
return 0
}
// NonNilInterfaceValue:
// ConcreteTypeName TypeSequence InterfaceContents
// ConcreteTypeName:
// uint(lengthOfName) [already read=n] name
// InterfaceContents:
// int(concreteTypeId) DelimitedValue
// DelimitedValue:
// uint(length) Value
func (deb *debugger) nonNilInterfaceValue(indent tab, nameLen int) {
// ConcreteTypeName
b := make([]byte, nameLen)
deb.r.Read(b) // TODO: CHECK THESE READS!!
deb.consumed(nameLen)
name := string(b)
for {
id := deb.typeId()
if id < 0 {
deb.typeDefinition(indent, -id)
n := deb.loadBlock(false)
deb.dump("Nested message of length %d", n)
} else {
// DelimitedValue
x := deb.uint64() // in case we want to ignore the value; we don't.
fmt.Fprintf(os.Stderr, "%sinterface value, type %q id=%d; valueLength %d\n", indent, name, id, x)
deb.value(indent, id)
break
}
}
}
// printCommonType prints a common type; used by printWireType.
func (deb *debugger) printCommonType(indent tab, kind string, common *CommonType) {
indent.print()
fmt.Fprintf(os.Stderr, "%s %q id=%d\n", kind, common.Name, common.Id)
}
// printWireType prints the contents of a wireType.
func (deb *debugger) printWireType(indent tab, wire *wireType) {
fmt.Fprintf(os.Stderr, "%stype definition {\n", indent)
indent++
switch {
case wire.ArrayT != nil:
deb.printCommonType(indent, "array", &wire.ArrayT.CommonType)
fmt.Fprintf(os.Stderr, "%slen %d\n", indent+1, wire.ArrayT.Len)
fmt.Fprintf(os.Stderr, "%selemid %d\n", indent+1, wire.ArrayT.Elem)
case wire.MapT != nil:
deb.printCommonType(indent, "map", &wire.MapT.CommonType)
fmt.Fprintf(os.Stderr, "%skey id=%d\n", indent+1, wire.MapT.Key)
fmt.Fprintf(os.Stderr, "%selem id=%d\n", indent+1, wire.MapT.Elem)
case wire.SliceT != nil:
deb.printCommonType(indent, "slice", &wire.SliceT.CommonType)
fmt.Fprintf(os.Stderr, "%selem id=%d\n", indent+1, wire.SliceT.Elem)
case wire.StructT != nil:
deb.printCommonType(indent, "struct", &wire.StructT.CommonType)
for i, field := range wire.StructT.Field {
fmt.Fprintf(os.Stderr, "%sfield %d:\t%s\tid=%d\n", indent+1, i, field.Name, field.Id)
}
case wire.GobEncoderT != nil:
deb.printCommonType(indent, "GobEncoder", &wire.GobEncoderT.CommonType)
}
indent--
fmt.Fprintf(os.Stderr, "%s}\n", indent)
}
// fieldValue prints a value of any type, such as a struct field.
// FieldValue:
// builtinValue | ArrayValue | MapValue | SliceValue | StructValue | InterfaceValue
func (deb *debugger) fieldValue(indent tab, id typeId) {
_, ok := builtinIdToType[id]
if ok {
if id == tInterface {
deb.interfaceValue(indent)
} else {
deb.printBuiltin(indent, id)
}
return
}
wire, ok := deb.wireType[id]
if !ok {
errorf("type id %d not defined", id)
}
switch {
case wire.ArrayT != nil:
deb.arrayValue(indent, wire)
case wire.MapT != nil:
deb.mapValue(indent, wire)
case wire.SliceT != nil:
deb.sliceValue(indent, wire)
case wire.StructT != nil:
deb.structValue(indent, id)
case wire.GobEncoderT != nil:
deb.gobEncoderValue(indent, id)
default:
panic("bad wire type for field")
}
}
// printBuiltin prints a value not of a fundamental type, that is,
// one whose type is known to gobs at bootstrap time.
func (deb *debugger) printBuiltin(indent tab, id typeId) {
switch id {
case tBool:
x := deb.int64()
if x == 0 {
fmt.Fprintf(os.Stderr, "%sfalse\n", indent)
} else {
fmt.Fprintf(os.Stderr, "%strue\n", indent)
}
case tInt:
x := deb.int64()
fmt.Fprintf(os.Stderr, "%s%d\n", indent, x)
case tUint:
x := deb.uint64()
fmt.Fprintf(os.Stderr, "%s%d\n", indent, x)
case tFloat:
x := deb.uint64()
fmt.Fprintf(os.Stderr, "%s%g\n", indent, float64FromBits(x))
case tComplex:
r := deb.uint64()
i := deb.uint64()
fmt.Fprintf(os.Stderr, "%s%g+%gi\n", indent, float64FromBits(r), float64FromBits(i))
case tBytes:
x := int(deb.uint64())
b := make([]byte, x)
deb.r.Read(b)
deb.consumed(x)
fmt.Fprintf(os.Stderr, "%s{% x}=%q\n", indent, b, b)
case tString:
x := int(deb.uint64())
b := make([]byte, x)
deb.r.Read(b)
deb.consumed(x)
fmt.Fprintf(os.Stderr, "%s%q\n", indent, b)
default:
panic("unknown builtin")
}
}
// ArrayValue:
// uint(n) FieldValue*n
func (deb *debugger) arrayValue(indent tab, wire *wireType) {
elemId := wire.ArrayT.Elem
u := deb.uint64()
length := int(u)
for i := 0; i < length; i++ {
deb.fieldValue(indent, elemId)
}
if length != wire.ArrayT.Len {
fmt.Fprintf(os.Stderr, "%s(wrong length for array: %d should be %d)\n", indent, length, wire.ArrayT.Len)
}
}
// MapValue:
// uint(n) (FieldValue FieldValue)*n [n (key, value) pairs]
func (deb *debugger) mapValue(indent tab, wire *wireType) {
keyId := wire.MapT.Key
elemId := wire.MapT.Elem
u := deb.uint64()
length := int(u)
for i := 0; i < length; i++ {
deb.fieldValue(indent+1, keyId)
deb.fieldValue(indent+1, elemId)
}
}
// SliceValue:
// uint(n) (n FieldValue)
func (deb *debugger) sliceValue(indent tab, wire *wireType) {
elemId := wire.SliceT.Elem
u := deb.uint64()
length := int(u)
deb.dump("Start of slice of length %d", length)
for i := 0; i < length; i++ {
deb.fieldValue(indent, elemId)
}
}
// StructValue:
// (uint(fieldDelta) FieldValue)*
func (deb *debugger) structValue(indent tab, id typeId) {
deb.dump("Start of struct value of %q id=%d\n<<\n", id.name(), id)
fmt.Fprintf(os.Stderr, "%s%s struct {\n", indent, id.name())
wire, ok := deb.wireType[id]
if !ok {
errorf("type id %d not defined", id)
}
strct := wire.StructT
fieldNum := -1
indent++
for {
delta := deb.uint64()
if delta == 0 { // struct terminator is zero delta fieldnum
break
}
fieldNum += int(delta)
if fieldNum < 0 || fieldNum >= len(strct.Field) {
deb.dump("field number out of range: prevField=%d delta=%d", fieldNum-int(delta), delta)
break
}
fmt.Fprintf(os.Stderr, "%sfield %d:\t%s\n", indent, fieldNum, wire.StructT.Field[fieldNum].Name)
deb.fieldValue(indent+1, strct.Field[fieldNum].Id)
}
indent--
fmt.Fprintf(os.Stderr, "%s} // end %s struct\n", indent, id.name())
deb.dump(">> End of struct value of type %d %q", id, id.name())
}
// GobEncoderValue:
// uint(n) byte*n
func (deb *debugger) gobEncoderValue(indent tab, id typeId) {
len := deb.uint64()
deb.dump("GobEncoder value of %q id=%d, length %d\n", id.name(), id, len)
fmt.Fprintf(os.Stderr, "%s%s (implements GobEncoder)\n", indent, id.name())
data := make([]byte, len)
_, err := deb.r.Read(data)
if err != nil {
errorf("gobEncoder data read: %s", err)
}
fmt.Fprintf(os.Stderr, "%s[% .2x]\n", indent+1, data)
}