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If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/ebml/README.md b/ebml/README.md new file mode 100644 index 0000000..f063143 --- /dev/null +++ b/ebml/README.md @@ -0,0 +1,89 @@ +Go-EBML +======= +A marshaler/unmarshaler for [EBML](http://ebml.sourceforge.net/). + +It's quite simple to use: +```go + +func ExampleMarshal() { + DoDad := new(struct { + EbmlId ebml.Id `ebml:"3f0000"` + DoHickey uint `ebml:"4242"` + ThingaMabob string `ebml:"4243"` + HumDinger int `ebml:"4244"` + }) + + DoDad.DoHickey = 70000 + DoDad.ThingaMabob = "huzah" + DoDad.HumDinger = -92387 + + b, _ := ebml.Marshal(*DoDad) + fmt.Printf("0x%x\n", b) + + // Output: + // 0x3f00009442428301117042438568757a6168424483fe971d +} + +func ExampleUnmarshal() { + data := []byte{ + 0x3f, 0x00, 0x00, 0x94, + 0x42, 0x42, 0x83, 0x01, 0x11, 0x70, + 0x42, 0x43, 0x85, 0x68, 0x75, 0x7a, 0x61, 0x68, + 0x42, 0x44, 0x83, 0xfe, 0x97, 0x1d, + } + + DoDad := new(struct { + EbmlId ebml.Id `ebml:"3f0000"` + DoHickey uint `ebml:"4242"` + ThingaMabob string `ebml:"4243"` + HumDinger int `ebml:"4244"` + }) + + ebml.Unmarshal(data, DoDad) + fmt.Printf("%v\n", DoDad) + // Output: + // &{0 70000 huzah -92387} +} + +``` + + +Caveats +------- +If an EBML DTD specifies a value as an unsigned integer, you must use a uint +type. For example: the uint32 8388608 and int -8388608 may encode to identical +0x800000 24 bit arrays in an EBML stream. + +EBML does not have a boolean type, but booleans are commonly defined in DTDs +as zero or non-zero usigned integers. + + +Not Implemented +--------------- +* Default values. +> Every non-container MAY be assigned a default value. If so, its +> value will be added to the interpretation of the EBML data if no +> element with another value exists in the data. +> +> As an example, consider this EBML DTD: +> +> Weight := 4101 { +> WeightValue := 41a1 uint; +> WeightUnit := 41a2 string [ def:"kilogram" ]; +> } +> +> If the Weight element only contains the WeightValue element, the +> WeightUnit element with value "kilogram" will be added when the +> information is semantically processed. A WeightUnit element with +> another value would of course override the default. +> +> The default value can also be a symbol referring back to a +> previously seen symbol. If however no such symbol has been seen, +> i.e. it has not been encoded into the EBML data and has no default +> value, the element will not be added as a child on the semantic +> level. +> +> Weight := 4101 { +> WeightValue := 41a1 uint; +> WeightUnit := 41a2 string [ def:WeightUnit ]; +> } diff --git a/ebml/cache.go b/ebml/cache.go new file mode 100644 index 0000000..dc74b91 --- /dev/null +++ b/ebml/cache.go @@ -0,0 +1,110 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +import ( + "reflect" + "sync" +) + +var ( + fieldIdMap = make(map[reflect.Type]map[Id]int) + fieldIdMutex sync.RWMutex + //fieldDecoderMap = make(map[reflect.Type][]decoderFunc) + //fieldDecoderMutex sync.RWMutex +) + +// cachedFieldIdMap returns a map that contains Id to field number +// mappings for typ +func cachedFieldIdMap(typ reflect.Type) map[Id]int { + fieldIdMutex.RLock() + m, ok := fieldIdMap[typ] + fieldIdMutex.RUnlock() + if ok { + return m + } + + // Didn't get a map, lock down the map + fieldIdMutex.Lock() + defer fieldIdMutex.Unlock() + m, ok = fieldIdMap[typ] + if ok { // the work is already done + return m + } + + m = make(map[Id]int) + // look over the fields + for i := 0; i < typ.NumField(); i++ { + f := typ.Field(i) + if f.Name == "EbmlId" { + continue + } + tag := f.Tag.Get("ebml") + if tag == "" || tag == "-" { + continue + } + id, err := NewIdFromString(tag) + if err != nil { + panic(ebmlError("ebml: could not parse Id from struct " + typ.String() + " field " + f.Name + ", " + err.Error())) + } + m[id] = i + } + fieldIdMap[typ] = m + return m +} + +/* + +// cachedFieldIpDecoderTable returns a slice that contains decoder functions +// indexed by field number +func cachedFieldDecoderTable(typ reflect.Type) []decoderFunc { + fieldDecoderMutex.RLock() + s, ok := fieldDecoderMap[typ] + fieldDecoderMutex.RUnlock() + if ok { + return s + } + + // Didn't get a slice, lock down the map + fieldDecoderMutex.Lock() + defer fieldDecoderMutex.Unlock() + s, ok = fieldDecoderMap[typ] + if ok { // the work is already done + return s + } + + // a struct should have its fields parsed by cachedFieldIdMap already, + // so this shouldn't be too sloppy to just pull it + m := fieldIdMap[typ] + + // create a map with pre-nil'ed functions for typ + s = make([]decoderFunc, typ.NumField()) + // look over the fields that could be decoded into + for _, i := range m { + f := typ.Field(i) + k := f.Type.Kind() + for k == reflect.Ptr { + k = f.Type.Elem().Kind() + } + switch k { + case reflect.Int, reflect.Int8, reflect.Int32, reflect.Int64: + s[i] = decodeInt + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + s[i] = decodeUinta + case reflect.Slice: + s[i] = decodeSlice + case reflect.String: + s[i] = decodeString + case reflect.Struct: + s[i] = decodeStruct + default: + decError(fmt.Sprintf("cannot decode to %s.%s, %s decoding is unsupported ", + typ, f.Name, f.Type.Kind())) + } + } + fieldDecoderMap[typ] = s + return s +} + +*/ diff --git a/ebml/decode.go b/ebml/decode.go new file mode 100644 index 0000000..dbde475 --- /dev/null +++ b/ebml/decode.go @@ -0,0 +1,339 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +import ( + "bytes" + "encoding/binary" + "fmt" + "io" + "reflect" + "time" +) + +// readIdFrom reads an Id from a Reader and returns the number of bytes read and the Id +func (d *Decoder) readId() (int, Id) { + n, err := d.r.Read(d.buf[:1]) + if err != nil { + decError(err.Error()) + } + + id := Id(d.buf[0]) + var buf []byte + switch { + case id >= 0x80: + return n, id + case id >= 0x40: + buf = d.buf[:1] + case id >= 0x20: + buf = d.buf[:2] + case id >= 0x10: + buf = d.buf[:3] + default: + p, err := d.r.Seek(-1, 1) + if err != nil { + decError(err.Error()) + } + d.r.Read(buf) + decError(fmt.Sprintf("invalid Id at reader position 0x%x or EBMLMaxIDLength > 4, next 8 bytes 0x%0.2x", p, buf)) + } + var nn int + nn, err = d.r.Read(buf) + n += nn + if err != nil { + decError(err.Error()) + } + for _, c := range buf { + id <<= 8 + id += Id(c) + } + return n, id +} + +// readSizeFrom reads a size from a Reader and returns the number of bytes read and the size +func (d *Decoder) readSize() (int, int64) { + n, err := d.r.Read(d.buf[:1]) + if err != nil { + decError(err.Error()) + } + size := int64(d.buf[0]) + var buf []byte + switch { + case size >= 0x80: + size -= 0x80 + return n, size + case size >= 0x40: + size -= 0x40 + buf = d.buf[:1] + case size >= 0x20: + size -= 0x20 + buf = d.buf[:2] + case size >= 0x10: + size -= 0x10 + buf = d.buf[:3] + case size >= 0x08: + size -= 0x08 + buf = d.buf[:4] + case size >= 0x04: + size -= 0x04 + buf = d.buf[:5] + case size >= 0x02: + size -= 0x02 + buf = d.buf[:6] + case size >= 0x01: + size -= 0x01 + buf = d.buf[:7] + } + var nn int + nn, err = d.r.Read(buf) + n += nn + if err != nil { + decError(err.Error()) + } + for _, c := range buf { + size <<= 8 + size += int64(c) + } + return n, size +} + +type decoderFunc func(d *Decoder, id Id, size int64, v reflect.Value) + +/* Sadly this using this table results in 'initialization loops' during building +var decoderFuncTable = [...]decoderFunc{ + reflect.Uint: decodeUint, + reflect.Uint8: decodeUint, + reflect.Uint16: decodeUint, + reflect.Uint32: decodeUint, + reflect.Uint64: decodeUint, + reflect.Float32: decodeFloat, + reflect.Float64: decodeFloat, + reflect.Slice: decodeSlice, + reflect.String: decodeString, + reflect.Struct: decodeStruct, +} +*/ + +func decodeValue(d *Decoder, id Id, size int64, v reflect.Value) { + if um, ok := v.Interface().(Unmarshaler); ok { + if v.Kind() == reflect.Ptr && v.IsNil() { + v.Set(reflect.New(v.Type().Elem())) + um = v.Interface().(Unmarshaler) + } + + rf := um.UnmarshalEBML(size) + r := io.LimitReader(d.r, size) + rf.ReadFrom(r) + return + } + + // If we got an interface or a pointer, dereference it. + for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface { + if v.IsNil() { + v.Set(reflect.New(v.Type().Elem())) + } + v = v.Elem() + } + + // look up the function to decode to value v + var fn decoderFunc + // I wanted to use an array of functions indexed by reflect.Kind, + // but kept getting initialization loop build errors + switch v.Kind() { + case reflect.Int, reflect.Int8, reflect.Int32, reflect.Int64: + fn = decodeInt + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + fn = decodeUint + case reflect.Float32: + fn = decodeFloat32 + case reflect.Float64: + fn = decodeFloat64 + case reflect.Slice: + fn = decodeSlice + case reflect.String: + fn = decodeString + case reflect.Struct: + if _, ok := v.Interface().(time.Time); ok { + fn = decodeTime + } else { + fn = decodeStruct + } + default: + decError(fmt.Sprintf("unsupported type %v", v.Type())) + } + fn(d, id, size, v) +} + +func decodeInt(d *Decoder, id Id, size int64, v reflect.Value) { + _, err := d.r.Read(d.buf[:size]) + x := int64(int8(d.buf[0])) + for _, c := range d.buf[1:size] { + x <<= 8 + x += int64(c) + } + if x == 0 { + return + } + if v.OverflowInt(x) { + decError(fmt.Sprintf("element %s value %d overflows %s", id, x, v.Type())) + } + v.SetInt(x) + if err != nil { + decError(err.Error()) + } +} + +func decodeUint(d *Decoder, id Id, size int64, v reflect.Value) { + _, err := d.r.Read(d.buf[:size]) + x := uint64(d.buf[0]) + for _, c := range d.buf[1:size] { + x <<= 8 + x += uint64(c) + } + if x == 0 { + return + } + if v.OverflowUint(x) { + decError(fmt.Sprintf("element %s value %d overflows %s", id, x, v.Type())) + } + v.SetUint(x) + if err != nil { + decError(err.Error()) + } +} + +func decodeFloat32(d *Decoder, id Id, size int64, v reflect.Value) { + var x float32 + if size != 4 { + decError(fmt.Sprintf("cannot decode a float of len %d to a float32", size)) + } + + buf := d.buf[:size] + _, err := d.r.Read(buf) + if err != nil && err != io.EOF { + decError(err.Error()) + } + err = binary.Read(bytes.NewReader(buf), binary.BigEndian, &x) + if err != nil { + println(fmt.Sprintf("%x", buf)) + decError(err.Error()) + } + v.SetFloat(float64(x)) +} + +func decodeFloat64(d *Decoder, id Id, size int64, v reflect.Value) { + var x float64 + if size != 8 { + decError(fmt.Sprintf("cannot decode a float of len %d to a float64", size)) + } + + buf := d.buf[:size] + _, err := d.r.Read(buf) + if err != nil && err != io.EOF { + decError(err.Error()) + } + err = binary.Read(bytes.NewReader(buf), binary.BigEndian, &x) + if err != nil { + println(fmt.Sprintf("%x", buf)) + decError(err.Error()) + } + v.SetFloat(x) +} + +func decodeSlice(d *Decoder, id Id, size int64, v reflect.Value) { + if _, ok := v.Interface().([]byte); ok { + var buf []byte + if size <= 8 { + buf = d.buf[:size] + } else { + buf = make([]byte, int(size)) + } + _, err := d.r.Read(buf) + v.Set(reflect.ValueOf(buf)) + if err != nil { + decError(err.Error()) + } + return + } + + // TODO(Emery): would be nice to use reflect.Append() + n := v.Len() + if n >= v.Cap() { + newcap := v.Cap() + v.Cap()/2 + if newcap < 4 { + newcap = 4 + } + newv := reflect.MakeSlice(v.Type(), n+1, newcap) + reflect.Copy(newv, v) + v.Set(newv) + } else { + v.SetLen(n + 1) + } + decodeValue(d, id, size, v.Index(n)) +} + +func decodeString(d *Decoder, id Id, size int64, v reflect.Value) { + buf := make([]byte, size) + _, err := d.r.Read(buf) + v.SetString(string(buf)) + if err != nil { + decError(err.Error()) + } +} + +func decodeStruct(d *Decoder, id Id, size int64, v reflect.Value) { + t := v.Type() + // get Id to field mappings + idField := cachedFieldIdMap(t) + // BUG(Emery): not caching decoder funtions for struct fields is suboptimal + //fieldFunc := cachedFieldDecoderTable(t) + + var n int + var subId Id + var subSize int64 + var ok bool + for size > 0 { + // read and and size + n, subId = d.readId() + size -= int64(n) + n, subSize = d.readSize() + size -= int64(n) + + // look up if the subId should decode into a field + if n, ok = idField[subId]; ok { + decodeValue(d, subId, subSize, v.Field(n)) + /* + subV = v.Field(n) + // Derefence pointer + for subV.Kind() == reflect.Ptr { + subV = subV.Elem() + } + + // use the cached decoder funtion for field + fieldFunc[n] + */ + } else { + d.r.Seek(size, 0) + } + size -= subSize + } +} + +func decodeTime(d *Decoder, id Id, size int64, v reflect.Value) { + if size != 8 { + decError(fmt.Sprintf("%d is an invalid length for a date value", size)) + } + _, err := d.r.Read(d.buf) + + date := time.Duration(int8(d.buf[0])) + for _, c := range d.buf[1:] { + date <<= 8 + date += time.Duration(c) + } + v.Set(reflect.ValueOf(epoch.Add(date))) // epoch defined in ebml.go + + if err != nil { + decError(err.Error()) + } +} diff --git a/ebml/ebml.go b/ebml/ebml.go new file mode 100644 index 0000000..273b34b --- /dev/null +++ b/ebml/ebml.go @@ -0,0 +1,128 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +/* +Package ebml marshals and unmarshals Go structs to and from +the Exensible Binary Markup Langauge. +*/ +package ebml + +import ( + "errors" + "fmt" + "reflect" + "strconv" + "time" +) + +// Header is a struct for encoding and decoding EBML streams. +// +// The following could be a valid top-level struct for +// representing Matroska streams: +// type Matroska struct { +// ebml.Header +// Segment []Segment `ebml:"18538067"` +// } +// +// You will however need to populate field values in Header +// to form a valid EBML document. +type Header struct { + // BUG(Emery): Setting default and fallback values in + // struct field tags is not supported. + EbmlId Id `ebml:"1a45dfa3"` + EBMLVersion uint8 `ebml:"4286"` + EBMLReadVersion uint8 `ebml:"42f7"` + EBMLMaxIDLength uint8 `ebml:"42f2"` + EBMLMaxSizeLength uint8 `ebml:"42f3"` + DocType string `ebml:"4282"` + DocTypeVersion uint8 `ebml:"4287"` + DocTypeReadVersion uint8 `ebml:"4285"` +} + +// Id is a type that identifies an ebml element. +type Id uint64 + +func (id Id) len() (l int64) { + switch { + case id > 0x80 && id < 0xFF: + l = 1 + case id > 0x4000 && id < 0x7FFF: + l = 2 + case id > 0x200000 && id < 0x3FFFFF: + l = 3 + case id > 0x10000000 && id < 0x3FFFFFFF: + l = 4 + } + return +} + +// Bytes returns an Id in byte slice form +func (id Id) bytes() []byte { + var l int + switch { + case id > 0x80 && id < 0xFF: + l = 1 + + case id > 0x4000 && id < 0x7FFF: + l = 2 + + case id > 0x200000 && id < 0x3FFFFF: + l = 3 + + case id > 0x10000000 && id < 0x3FFFFFFF: + l = 4 + + default: + panic(fmt.Errorf("invalid element ID %s", id)) + } + b := make([]byte, l) + for l > 1 { + l-- + b[l] = byte(id) + id >>= 8 + } + b[0] = byte(id) + return b +} + +// NewIdFromString is a convience fuction that returns an Id +// for a string of hexadecimal. +func NewIdFromString(s string) (Id, error) { + x, err := strconv.ParseUint(s, 16, 64) + if err != nil { + return 0, err + } + return Id(x), nil +} + +// String implements the Stringer interface, returning Id in +// hexadecimal form. +func (id Id) String() string { + return strconv.FormatUint(uint64(id), 16) +} + +// getId parses a struct for "EbmlId" +func getId(v reflect.Value) (id Id) { + v = reflect.Indirect(v) + t := v.Type() + if f, ok := t.FieldByName("EbmlId"); ok { + id = v.FieldByIndex(f.Index).Interface().(Id) + if id == 0 { + var err error + id, err = NewIdFromString(f.Tag.Get("ebml")) + if err != nil { + panic(errors.New("cannot resolve EBML Id for " + t.Name() + ", " + err.Error())) + } + } + } else { + if n := t.Name(); n == "" { + panic(errors.New("cannot resolve EBML Id for anonymous struct")) + } else { + panic(errors.New("cannot resolve EBML Id for " + n)) + } + } + return +} + +// EBML epoch is the beginning of this millennium +var epoch = time.Date(2001, time.January, 1, 0, 0, 0, 0, time.UTC) diff --git a/ebml/ebml_test.go b/ebml/ebml_test.go new file mode 100644 index 0000000..e730caa --- /dev/null +++ b/ebml/ebml_test.go @@ -0,0 +1,370 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +import ( + "bytes" + "io" + "io/ioutil" + "math/rand" + "reflect" + "testing" + "time" +) + +func init() { + rand.Seed(time.Now().UnixNano()) +} + +/* +func ExampleHeader() { + var headerA, headerB Header + headerA.EBMLVersion = 1 + headerA.EBMLReadVersion = 1 + headerA.EBMLMaxIDLength = 1 + headerA.EBMLMaxSizeLength = 1 + headerA.DocType = "matroska" + headerA.DocTypeVersion = 1 + headerA.DocTypeReadVersion = 1 + + b, _ := Marshal(headerA) + + src := bytes.NewReader(b) + dec := NewDecoder(src) + + dec.Decode(&headerB) + + fmt.Printf("0x%x DeepEqual: %v", b, reflect.DeepEqual(headerA, headerB)) + // Output: + // 0x1a45dfa3a34286810142f7810142f2810142f381014282886d6174726f736b614287810142858101 DeepEqual: true +} + +func ExampleMarshal() { + DoDad := new(struct { + EbmlId Id `ebml:"3f0000"` + DoHickey uint `ebml:"4242"` + ThingaMabob string `ebml:"4243"` + HumDinger int `ebml:"4244"` + }) + + DoDad.DoHickey = 70000 + DoDad.ThingaMabob = "huzah" + DoDad.HumDinger = -92387 + + b, err := Marshal(*DoDad) + if err != nil { + fmt.Println(err) + } + fmt.Printf("0x%x\n", b) + + // Output: + // 0x3f00009442428301117042438568757a6168424483fe971d +} + +func ExampleUnmarshal() { + data := []byte{ + 0x3f, 0x00, 0x00, 0x94, + 0x42, 0x42, 0x83, 0x01, 0x11, 0x70, + 0x42, 0x43, 0x85, 0x68, 0x75, 0x7a, 0x61, 0x68, + 0x42, 0x44, 0x83, 0xfe, 0x97, 0x1d, + } + + DoDad := new(struct { + EbmlId Id `ebml:"3f0000"` + DoHickey uint `ebml:"4242"` + ThingaMabob string `ebml:"4243"` + HumDinger int `ebml:"4244"` + }) + + err := Unmarshal(data, DoDad) + if err != nil { + fmt.Println(err) + } + fmt.Printf("%v\n", DoDad) + // Output: + // &{0 70000 huzah -92387} +} +*/ + +type intTestStruct struct { + EbmlId Id `ebml:"81"` + I int `ebml:"88"` +} + +func TestInt(t *testing.T) { + var in, out intTestStruct + in.I = rand.Int() + + buf, err := Marshal(in) + if err != nil { + t.Fatalf("marshal int %d: %s\n buf: %x", in.I, err, buf) + return + } + + err = Unmarshal(buf, &out) + if err != nil && err != io.EOF { + t.Fatalf("unmarshal int %d: %s\n buf: %x", in.I, err, buf) + return + } + if !reflect.DeepEqual(in, out) { + t.Fatalf("marshal and unmarshal int: in=%0.2x out=%0.2x", in.I, out.I) + return + } + +} + +func BenchmarkMarshalInt(b *testing.B) { + var ( + in intTestStruct + buf []byte + err error + ) + in.I = rand.Int() + for i := 0; i < b.N; i++ { + _, err = Marshal(in) + if err != nil { + b.Fatalf("marshal int %d: %s\n buf: %x", in.I, err, buf) + } + } +} + +func BenchmarkUnmarshalInt(b *testing.B) { + var ( + in, out intTestStruct + buf []byte + err error + ) + in.I = rand.Int() + buf, err = Marshal(in) + if err != nil { + b.Fatalf("marshal int %d: %s\n buf: %x", in.I, err, buf) + return + } + for i := 0; i < b.N; i++ { + err = Unmarshal(buf, &out) + if err != nil && err != io.EOF { + b.Fatalf("unmarshal int %d: %s\n buf: %x", in.I, err, buf) + return + } + } +} + +type uintTestStruct struct { + EbmlId Id `ebml:"81"` + I uint `ebml:"88"` +} + +func TestUint(t *testing.T) { + var in, out uintTestStruct + + in.I = uint(rand.Int63()) + buf, err := Marshal(in) + if err != nil { + t.Fatalf("marshal uint %d: %s\n buf: %x", in.I, err, buf) + } + + err = Unmarshal(buf, &out) + if err != nil && err != io.EOF { + t.Fatalf("unmarshal uint %d: %s\n buf: %x", in.I, err, buf) + } + + if !reflect.DeepEqual(in, out) { + t.Fatalf("marshal and unmarshal uint: in=%0.2x out=%0.2x", in.I, out.I) + } +} + +func BenchmarkMarshalUint(b *testing.B) { + var ( + in uintTestStruct + err error + ) + + in.I = uint(rand.Int63()) + for i := 0; i < b.N; i++ { + if _, err = Marshal(in); err != nil { + b.Fatalf("marshal uint %d: %s\n buf: %x", in.I, err) + } + } +} + +func BenchmarkUnmarshalUint(b *testing.B) { + var ( + in, out uintTestStruct + buf []byte + err error + ) + + in.I = uint(rand.Int63()) + buf, err = Marshal(in) + if err != nil { + b.Fatalf("marshal uint %d: %s\n buf: %x", in.I, err, buf) + } + for i := 0; i < b.N; i++ { + if err = Unmarshal(buf, &out); err != nil && err != io.EOF { + b.Fatalf("unmarshal uint %d: %s\n buf: %x", in.I, err, buf) + } + } +} + +type floatTestStruct struct { + EbmlId Id `ebml:"81"` + F float32 `ebml:"88"` + FF float64 `ebml:"89"` +} + +func TestFloat(t *testing.T) { + var in, out floatTestStruct + + in.F, in.FF = rand.Float32(), rand.Float64() + buf, err := Marshal(in) + if err != nil { + t.Fatalf("encode floats %f %f: %s\nbuf: %x", in.F, in.FF, err, buf) + return + } + if err = Unmarshal(buf, &out); err != nil { + t.Fatalf("decode floats %f %f: %s\nbuf: %x", in.FF, in.FF, err, buf) + return + } + if !reflect.DeepEqual(in, out) { + t.Errorf("encode/decode float mismatch: in=%f,%f out=%f,%f\n%x", in.F, in.FF, out.F, out.FF, buf) + return + } +} + +func BenchmarkMarshalFloat(b *testing.B) { + var ( + in floatTestStruct + err error + ) + in.F, in.FF = rand.Float32(), rand.Float64() + + for i := 0; i < b.N; i++ { + if _, err = Marshal(in); err != nil { + b.Fatalf("encode floats %f %f: %s\nbuf: %x", in.F, in.FF, err) + } + } +} + +func BenchmarkUnmarshalFloat(b *testing.B) { + var ( + in, out floatTestStruct + buf []byte + err error + ) + in.F, in.FF = rand.Float32(), rand.Float64() + if buf, err = Marshal(in); err != nil { + b.Fatalf("encode floats %f %f: %s\nbuf: %x", in.F, in.FF, err, buf) + return + } + for i := 0; i < b.N; i++ { + if err = Unmarshal(buf, &out); err != nil { + b.Fatalf("decode floats %f %f: %s", in.F, in.FF, err) + } + } +} + +type dateTestStruct struct { + EbmlId Id `ebml:"81"` + D time.Time `ebml:"82"` +} + +func TestDate(t *testing.T) { + now := time.Now() + I := rand.Int63n(1 << 62) + + var in, out dateTestStruct + + for i := 0; i < 32; i++ { + date := now.Add(time.Duration(I)) + + in.D = date + buf, err := Marshal(in) + if err != nil { + t.Fatalf("marshal time.Time %v: %s\n buf: %x", date, err, buf) + } + + err = Unmarshal(buf, &out) + if err != nil && err != io.EOF { + t.Fatalf("unmarshal time.Time %v: %s\n buf: %x", date, err, buf) + } + + if !in.D.Equal(out.D) { + t.Fatalf("marshal and unmarshal time.Time: in=%v out=%v", in.D, out.D) + } + } +} + +type stringTest struct { + EbmlId Id `ebml:"81"` + S string `ebml:"82"` +} + +func TestString(t *testing.T) { + var in, out stringTest + in.S = "wrong me not good sister, nor wrong yourself" + buf, err := Marshal(in) + if err != nil { + t.Fatal("marshal string failed:", err) + } + if err = Unmarshal(buf, &out); err != nil { + t.Fatalf("unmarshal string failed: %s\n %x", err, buf) + } + + if in.S != out.S { + t.Fatalf("%s != %s\n%x", in.S, out.S, buf) + } +} + +type benchTestStruct struct { + EbmlId Id `ebml:"81"` + A uint `ebml:"4011"` + B int64 `ebml:"200011"` + C float64 `ebml:"10000011"` + D string `ebml:"3FFFFFFE"` +} + +func BenchmarkEncoding(b *testing.B) { + var test benchTestStruct + test.A = uint(rand.Int63()) + test.B = rand.Int63() + test.C = rand.Float64() + test.D = "of ships and sails and whether pigs have wings" + + var err error + b.ResetTimer() + enc := NewEncoder(ioutil.Discard) + for i := 0; i < b.N; i++ { + err = enc.Encode(test) + if err != nil { + b.Fatal(err.Error()) + } + } +} + +func BenchmarkDecoding(b *testing.B) { + control := new(benchTestStruct) + + control.A = uint(rand.Int63()) + control.B = rand.Int63() + control.C = rand.Float64() + control.D = "of ships and sails and whether pigs have wings" + + buf, err := Marshal(control) + r := bytes.NewReader(buf) + b.ResetTimer() + + dec := NewDecoder(r) + for i := 0; i < b.N; i++ { + var test benchTestStruct + err = dec.Decode(&test) + if err != nil { + b.Fatal(err.Error()) + } + + if !reflect.DeepEqual(control, test) { + b.Fatalf("not equal\n%v\n%v", control, test) + } + r.Seek(0, 0) + } +} diff --git a/ebml/encode.go b/ebml/encode.go new file mode 100644 index 0000000..03d761a --- /dev/null +++ b/ebml/encode.go @@ -0,0 +1,421 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +import ( + "encoding/binary" + "fmt" + "io" + "reflect" + "time" +) + +var indent string + +type encoder interface { + io.WriterTo + Size() int64 +} + +type containerElement struct { + // These []bytes can probably be merged + id Id + size int64 + header []byte + elements []encoder +} + +func (ce *containerElement) Append(e encoder) { + ce.elements = append(ce.elements, e) + ce.size += e.Size() +} + +func (ce *containerElement) Size() (n int64) { + ce.header = append(ce.id.bytes(), marshalSize(ce.size)...) + return int64(len(ce.header)) + ce.size +} + +func (ce *containerElement) WriteTo(w io.Writer) (n int64, err error) { + if len(ce.header) == 0 { + ce.Size() // top level elements don't get Size called + } + var N int + var nn int64 + N, err = w.Write(ce.header) + if err != nil { + return + } + n += int64(N) + + for _, e := range ce.elements { + nn, err = e.WriteTo(w) + n += nn + if err != nil { + break + } + } + return +} + +type simpleElement []byte + +func (b simpleElement) Size() int64 { return int64(len(b)) } +func (b simpleElement) WriteTo(w io.Writer) (int64, error) { + n, err := w.Write(b) + return int64(n), err +} + +// sliceElement is a encoder for holding groups of elements, such as a group +// elements of the same type that occur more than once in a container. +type sliceElement []encoder + +func (se sliceElement) Size() (n int64) { + for _, e := range se { + n += e.Size() + } + return +} + +func (se sliceElement) WriteTo(w io.Writer) (n int64, err error) { + var nn int64 + for _, e := range se { + nn, err = e.WriteTo(w) + n += nn + if err != nil { + break + } + } + return +} + +type marshalerElement struct { + id Id + size int64 + header []byte + wt io.WriterTo +} + +func (me *marshalerElement) Size() int64 { return me.size } + +func (me *marshalerElement) WriteTo(w io.Writer) (n int64, err error) { + var N int + var nn int64 + N, err = w.Write(me.header) + n = int64(N) + if err != nil { + return + } + nn, err = me.wt.WriteTo(w) + n += nn + return +} + +func unsupportedTypeError(typ reflect.Type) { + encError("unsupported type: " + typ.String()) +} + +func isEmptyValue(v reflect.Value) bool { + switch v.Kind() { + case reflect.Array, reflect.Slice, reflect.String: + return v.Len() == 0 + case reflect.Interface, reflect.Ptr: + return v.IsNil() + } + return false +} + +func encode(id Id, v reflect.Value) encoder { + if m, ok := v.Interface().(Marshaler); ok { + size, wt := m.MarshalEBML() + header := append(id.bytes(), marshalSize(size)...) + return &marshalerElement{id, size, header, wt} + } + + if t, ok := v.Interface().(time.Time); ok { + return encodeTime(id, t) + } + + for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface { + v = v.Elem() + } + + switch v.Kind() { + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + x := v.Int() + return marshalInt(id, x) + + case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: + x := v.Uint() + return marshalUint(id, x) + + case reflect.Float32: + return float32Element{id, v.Interface().(float32)} + + case reflect.Float64: + return float64Element{id, v.Interface().(float64)} + + case reflect.String: + return encodeString(id, v) + + case reflect.Slice: + return encodeSlice(id, v) + + case reflect.Struct: + return encodeStruct(id, v) + } + unsupportedTypeError(v.Type()) + return nil +} + +const ( + o1 = 1<<7 - 2 + o2 = 1<<14 - 2 + o3 = 1<<21 - 2 + o4 = 1<<28 - 2 + o5 = 1<<35 - 2 + o6 = 1<<42 - 2 + o7 = 1<<49 - 2 + o8 = 1<<56 - 2 +) + +// MarshalSize returns the EBML variable width representation +// of an element's size +func marshalSize(x int64) []byte { + var s int + var m byte + + switch { + case x == 0: + return []byte{byte(0x80)} + case x < o1: + return []byte{byte(0x80) | byte(x)} + case x < o2: + s = 2 + m = 0x40 + case x < o3: + s = 3 + m = 0x20 + case x < o4: + s = 4 + m = 0x10 + case x < o5: + s = 5 + m = 0x08 + case x < o6: + s = 6 + m = 0x04 + case x < o7: + s = 7 + m = 0x02 + case x < o8: + s = 8 + m = 0x01 + default: + encError(fmt.Sprintf("element size %d overflows", x)) + } + b := make([]byte, s) + s-- + for s > 0 { + b[s] = byte(x) + x >>= 8 + s-- + } + b[0] = byte(x) | m + return b +} + +func marshalInt(id Id, x int64) encoder { + var xl int + if x > 0 { + switch { + case x < 0x80: + xl = 1 + case x < 0x8000: + xl = 2 + case x < 0x800000: + xl = 3 + case x < 0x80000000: + xl = 4 + case x < 0x8000000000: + xl = 5 + case x < 0x800000000000: + xl = 6 + case x < 0x80000000000000: + xl = 7 + default: + xl = 8 + } + } else { + switch { + case x > -0x7F: + xl = 1 + case x > -0x7FFF: + xl = 2 + case x > -0x7FFFFF: + xl = 3 + case x > -0x7FFFFFFF: + xl = 4 + case x > -0x7FFFFFFFFF: + xl = 5 + case x > -0x7FFFFFFFFFFF: + xl = 6 + case x > -0x7FFFFFFFFFFFFF: + xl = 7 + default: + xl = 8 + } + } + + idBuf := id.bytes() + l := len(idBuf) + 1 + xl + b := make(simpleElement, l) + p := copy(b, idBuf) + b[p] = 0x80 | byte(xl) + p++ + + l-- + b[l] = byte(x) + for l > p { + l-- + x >>= 8 + b[l] = byte(x) + } + return b +} + +func marshalUint(id Id, x uint64) encoder { + var xl int + switch { + case x < 0xFF: + xl = 1 + case x < 0xFFFF: + xl = 2 + case x < 0xFFFFFF: + xl = 3 + case x < 0xFFFFFFFF: + xl = 4 + case x < 0xFFFFFFFFFF: + xl = 5 + case x < 0xFFFFFFFFFFFF: + xl = 6 + case x < 0xFFFFFFFFFFFFFF: + xl = 7 + default: + xl = 8 + } + idBuf := id.bytes() + + l := len(idBuf) + 1 + xl + b := make(simpleElement, l) + p := copy(b, idBuf) + b[p] = 0x80 | byte(xl) + p++ + + l-- + b[l] = byte(x) + for l > p { + l-- + x >>= 8 + b[l] = byte(x) + } + return b +} + +type float32Element struct { + id Id + f float32 +} + +func (e float32Element) Size() int64 { return e.id.len() + 5 } +func (e float32Element) WriteTo(w io.Writer) (int64, error) { + n, err := w.Write(e.id.bytes()) + if err == nil { + _, err = w.Write([]byte{0x84}) + if err == nil { + err = binary.Write(w, binary.BigEndian, e.f) + n += 5 + } + } + return int64(n), err +} + +type float64Element struct { + id Id + f float64 +} + +func (e float64Element) Size() int64 { return e.id.len() + 9 } +func (e float64Element) WriteTo(w io.Writer) (int64, error) { + n, err := w.Write(e.id.bytes()) + if err == nil { + _, err = w.Write([]byte{0x88}) + if err == nil { + n++ + err = binary.Write(w, binary.BigEndian, e.f) + } else { + n += 8 + } + } + return int64(n), err +} + +func encodeSlice(id Id, v reflect.Value) encoder { + if bs, ok := v.Interface().([]byte); ok { + idBuf := id.bytes() + sizeBuf := marshalSize(int64(len(bs))) + buf := make(simpleElement, len(idBuf)+len(sizeBuf)+len(bs)) + n := copy(buf, idBuf) + n += copy(buf[n:], sizeBuf) + copy(buf[n:], bs) + return buf + } + + l := v.Len() + s := make(sliceElement, l) + for i := 0; i < l; i++ { + s[i] = encode(id, v.Index(i)) + } + return s +} + +func encodeString(id Id, v reflect.Value) encoder { + sb := []byte(v.String()) + l := len(sb) + sz := marshalSize(int64(l)) + idBuf := id.bytes() + b := make(simpleElement, len(idBuf)+len(sz)+l) + n := copy(b, idBuf) + n += copy(b[n:], sz) + copy(b[n:], sb) + return b +} + +func encodeStruct(id Id, v reflect.Value) encoder { + e := &containerElement{id: id} + for fid, i := range cachedFieldIdMap(v.Type()) { + fv := v.Field(i) + if !fv.IsValid() || isEmptyValue(fv) { + continue + } + fe := encode(fid, fv) + if e != nil { + e.Append(fe) + } + } + return e +} + +func encodeTime(id Id, t time.Time) encoder { + d := t.Sub(epoch) // epoch defined in ebml.go + + idb := id.bytes() + b := make(simpleElement, len(idb)+9) + n := copy(b, idb) + b[n] = 0x88 // length will be 8 + for i := len(b) - 1; i > n; i-- { + b[i] = byte(d) + d >>= 8 + } + return b +} diff --git a/ebml/error.go b/ebml/error.go new file mode 100644 index 0000000..130d405 --- /dev/null +++ b/ebml/error.go @@ -0,0 +1,17 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +// A ebmlError is used to distinguish errors (panics) generated in this package. +type ebmlError string + +func (e ebmlError) Error() string { return string(e) } + +func encError(s string) { + panic(ebmlError("ebml encoder: " + s)) +} + +func decError(s string) { + panic(ebmlError("ebml decoder: " + s)) +} diff --git a/ebml/file.go b/ebml/file.go new file mode 100644 index 0000000..9979b7d --- /dev/null +++ b/ebml/file.go @@ -0,0 +1,94 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +import ( + "bufio" + "io" + "os" +) + +type fileAbstraction struct { + filename string + info os.FileInfo +} + +// NewFileMarshaler returns a Marshaler that reads from a file +// during encoding. +func NewFileMarshaler(filename string) (Marshaler, error) { + info, err := os.Stat(filename) + if err != nil { + return nil, err + } + return &fileAbstraction{filename, info}, nil +} + +func (f *fileAbstraction) MarshalEBML() (size int64, wt io.WriterTo) { + return f.info.Size(), f +} + +func (f *fileAbstraction) WriteTo(w io.Writer) (written int64, err error) { + var file *os.File + file, err = os.Open(f.filename) + if err != nil { + return + } + defer file.Close() + // let bufio handle the details + return bufio.NewReader(file).WriteTo(w) +} + +// NewFileUnmarshaler returns an Unmarshaler that writes to a file +// during decoding. +func NewFileUnmarshaler(filename string) (Unmarshaler, error) { + info, err := os.Stat(filename) + if err == nil { + return &fileAbstraction{filename, info}, nil + } + + // create the file to check write permission before decoding. + if !os.IsNotExist(err) { + return nil, err + } + + var file *os.File + file, err = os.OpenFile(filename, os.O_CREATE|os.O_EXCL, 0666) + if err != nil { + return nil, err + } + defer file.Close() + + // try again + info, err = os.Stat(filename) + if err != nil { + return nil, err + } + return &fileAbstraction{filename, info}, nil +} + +func (f *fileAbstraction) UnmarshalEBML(n int64) io.ReaderFrom { + if f.info.Size() != n { + err := os.Truncate(f.filename, n) + if err != nil { + panic(err) + } + } + return f +} + +func (f *fileAbstraction) ReadFrom(r io.Reader) (readed int64, err error) { + var file *os.File + file, err = os.OpenFile(f.filename, os.O_WRONLY, 0) + if err != nil { + return + } + defer file.Close() + // let bufio handle the details + return bufio.NewWriter(file).ReadFrom(r) +} + +var ( + _ Marshaler = (*fileAbstraction)(nil) + _ Unmarshaler = (*fileAbstraction)(nil) +) diff --git a/ebml/file_test.go b/ebml/file_test.go new file mode 100644 index 0000000..929c71a --- /dev/null +++ b/ebml/file_test.go @@ -0,0 +1,35 @@ +// +build file +// This test is only run with the "file" build tag, +// as it touches the filesystem and needs a test file. + +package ebml + +import "testing" + +func TestFile(t *testing.T) { + fm, err := NewFileMarshaler("/tmp/test.in") + if err != nil { + t.Fatal("NewFileMarshaler:", err) + } + x := &struct { + EbmlId Id `ebml:"81"` + F Marshaler `ebml:"82"` + }{F: fm} + b, err := Marshal(x) + if err != nil { + t.Fatal("Marshal:", err) + } + + fu, err := NewFileUnmarshaler("/tmp/test.out") + if err != nil { + t.Fatal("NewFileUnmarshaler:", err) + } + y := &struct { + EbmlId Id `ebml:"81"` + F Unmarshaler `ebml:"82"` + }{F: fu} + err = Unmarshal(b, y) + if err != nil { + t.Fatal("Unmarshal:", err) + } +} diff --git a/ebml/idtest/idtest.go b/ebml/idtest/idtest.go new file mode 100644 index 0000000..99e040e --- /dev/null +++ b/ebml/idtest/idtest.go @@ -0,0 +1,43 @@ +// idtest is a utility for checking the validity of EBML ids +package main + +import ( + "fmt" + "github.com/ehmry/encoding/ebml" + "os" +) + +func main() { + for _, s := range os.Args[1:] { + id, err := ebml.NewIdFromString(s) + if err != nil { + fmt.Println(err) + continue + } + + b := id.Bytes() + c := b[0] + var good bool + switch l := len(b); l { + case 1: + good = c <= 0xff && c > 0x80 + case 2: + good = c <= 0x7f && c > 0x40 + case 3: + good = c <= 0x3f && c > 0x20 + case 4: + good = c <= 0x1f && c > 0x10 + } + + if good { + fmt.Print("Id is good: ") + } else { + fmt.Print("Id is bad: ") + } + fmt.Printf("% 11s ", id) + for _, c := range b { + fmt.Printf(".%08b", c) + } + fmt.Println() + } +} diff --git a/ebml/stream.go b/ebml/stream.go new file mode 100644 index 0000000..aa7f3a8 --- /dev/null +++ b/ebml/stream.go @@ -0,0 +1,155 @@ +// Copyright © 2013 Emery Hemingway +// Released under the terms of the GNU Public License version 3 + +package ebml + +import ( + "bytes" + "fmt" + "io" + "reflect" + "runtime" +) + +// An Encoder writes EBML data to an output stream. +type Encoder struct { + w io.Writer + err error +} + +// NewEncoder returns a new Encoder that writes to w. +func NewEncoder(w io.Writer) *Encoder { + return &Encoder{w: w} +} + +// Encode writes the EBML binary encoding of element to an Encoder stream. +func (enc *Encoder) Encode(element interface{}) (err error) { + if enc.err != nil { + return enc.err + } + + // encoding doesn't use error internally, but panics if there is a + // problem and then unwinds up to here. + defer func() { + if r := recover(); r != nil { + if _, ok := r.(runtime.Error); ok { + panic(r) + } + err = r.(error) + } + }() + + v := reflect.ValueOf(element) + id := getId(v) + + elem := encode(id, v) + if elem != nil { + _, err = elem.WriteTo(enc.w) + } + return +} + +// A Decoder decodes EBML data from a ReadSeeker +type Decoder struct { + r io.ReadSeeker + buf []byte // this is a resuable buffer for decoding + err error +} + +// NewDecoder returns a new decoder that decodes from r. +func NewDecoder(r io.ReadSeeker) *Decoder { + // TODO(Emery): just ask for a io.Reader and try and make it + // an io.ReadSeeker + return &Decoder{r: r, buf: make([]byte, 8)} +} + +// Decode decodes a EBML stream into v. +func (d *Decoder) Decode(element interface{}) (err error) { + if d.err != nil { + return d.err + } + + // decoding doesn't use error internally, but panics if there is a + // problem and then unwinds up to here. + defer func() { + if r := recover(); r != nil { + if _, ok := r.(runtime.Error); ok { + panic(r) + } + err = r.(error) + } + }() + + v := reflect.ValueOf(element) + for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface { + v = v.Elem() + } + + id := getId(v) + if n, curId := d.readId(); id != curId { + d.r.Seek(int64(-n), 0) + return fmt.Errorf("ebml: read stream positioned at element %s not %s", curId, id) + } + _, size := d.readSize() + + decodeValue(d, id, size, v) + return +} + +// Marshal returns an EBML representation of element. +// +// Marshal first determines the Id of element from the field named 'EbmlId', +// then recursively traverses element. Any exported struct field of element +// with an `ebml` tag will be including in marshalling, with the exception +// of fields tagged with `ebml:"-"`. +// +// The ebml tag should contain a valid EBML id, see the EBML documention for +// what constitutes a valid id. +func Marshal(element interface{}) ([]byte, error) { + buf := new(bytes.Buffer) + encoder := NewEncoder(buf) + err := encoder.Encode(element) + return buf.Bytes(), err +} + +// Unmarshal unmarshals EBML data into element. +// +// Unmarshal first determines the Id of element from the field named 'EbmlId', +// then recursively traverses element. Any exported struct field of element +// with an `ebml` tag will be including in unmarshalling, with the exception +// of fields tagged with `ebml:"-"`. +// +// The ebml tag should contain a valid EBML id, see the EBML documention for +// what constitutes a valid id. +func Unmarshal(data []byte, element interface{}) error { + return NewDecoder(bytes.NewReader(data)).Decode(element) +} + +// Marshaler is the interface implemented by objects that +// can marshal themselves into an EBML stream. The WriterTo +// should only Write element data, and not the id and size +// header of the element. size is the length of the data that +// shall be written and is used to build the element header +// and compute the size of the parent element before it is +// writen to an EBML stream. +type Marshaler interface { + // BUG(Emery): an embedded Marshaler will trample on a struct + MarshalEBML() (size int64, wt io.WriterTo) +} + +// Unmarshaler is the interface implemented by objects that +// can unmarshal themselves from an EBML stream. The data +// read into ReaderFrom will contain the data for the element +// being unmarshaled, and not an id or size header. +// +// n shall be the size of the element data, and it is not the +// resposibility of an Unmarshaler to limit reading to n. +// +// An Unmarshaler is usually sent to the decoding engine as a nil pointer +// in a struct and created when a tagged element is encountered, for this +// reason the UnmarshalEBML method should behave as if the Unmarshaler is +// at a zero value state. +type Unmarshaler interface { + // BUG(Emery): an embedded Unmarshaler will trample on a struct + UnmarshalEBML(n int64) io.ReaderFrom +}