diff options
Diffstat (limited to 'vendor/github.com/lunixbochs/struc/field.go')
-rw-r--r-- | vendor/github.com/lunixbochs/struc/field.go | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/vendor/github.com/lunixbochs/struc/field.go b/vendor/github.com/lunixbochs/struc/field.go new file mode 100644 index 0000000..4af10a7 --- /dev/null +++ b/vendor/github.com/lunixbochs/struc/field.go @@ -0,0 +1,281 @@ +package struc + +import ( + "bytes" + "encoding/binary" + "fmt" + "math" + "reflect" +) + +type Field struct { + Name string + CanSet bool + Ptr bool + Index int + Type Type + defType Type + Array bool + Slice bool + Len int + Order binary.ByteOrder + Sizeof []int + Sizefrom []int + Fields Fields + kind reflect.Kind +} + +func (f *Field) String() string { + var out string + if f.Type == Pad { + return fmt.Sprintf("{type: Pad, len: %d}", f.Len) + } else { + out = fmt.Sprintf("type: %s, order: %v", f.Type.String(), f.Order) + } + if f.Sizefrom != nil { + out += fmt.Sprintf(", sizefrom: %v", f.Sizefrom) + } else if f.Len > 0 { + out += fmt.Sprintf(", len: %d", f.Len) + } + if f.Sizeof != nil { + out += fmt.Sprintf(", sizeof: %v", f.Sizeof) + } + return "{" + out + "}" +} + +func (f *Field) Size(val reflect.Value, options *Options) int { + typ := f.Type.Resolve(options) + size := 0 + if typ == Struct { + vals := []reflect.Value{val} + if f.Slice { + vals = make([]reflect.Value, val.Len()) + for i := 0; i < val.Len(); i++ { + vals[i] = val.Index(i) + } + } + for _, val := range vals { + size += f.Fields.Sizeof(val, options) + } + } else if typ == Pad { + size = f.Len + } else if f.Slice || f.kind == reflect.String { + length := val.Len() + if f.Len > 1 { + length = f.Len + } + size = length * typ.Size() + } else if typ == CustomType { + return val.Addr().Interface().(Custom).Size(options) + } else { + size = typ.Size() + } + align := options.ByteAlign + if align > 0 && size < align { + size = align + } + return size +} + +func (f *Field) packVal(buf []byte, val reflect.Value, length int, options *Options) (size int, err error) { + order := f.Order + if options.Order != nil { + order = options.Order + } + if f.Ptr { + val = val.Elem() + } + typ := f.Type.Resolve(options) + switch typ { + case Struct: + return f.Fields.Pack(buf, val, options) + case Bool, Int8, Int16, Int32, Int64, Uint8, Uint16, Uint32, Uint64: + size = typ.Size() + var n uint64 + switch f.kind { + case reflect.Bool: + if val.Bool() { + n = 1 + } else { + n = 0 + } + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + n = uint64(val.Int()) + default: + n = val.Uint() + } + switch typ { + case Bool: + if n != 0 { + buf[0] = 1 + } else { + buf[0] = 0 + } + case Int8, Uint8: + buf[0] = byte(n) + case Int16, Uint16: + order.PutUint16(buf, uint16(n)) + case Int32, Uint32: + order.PutUint32(buf, uint32(n)) + case Int64, Uint64: + order.PutUint64(buf, uint64(n)) + } + case Float32, Float64: + size = typ.Size() + n := val.Float() + switch typ { + case Float32: + order.PutUint32(buf, math.Float32bits(float32(n))) + case Float64: + order.PutUint64(buf, math.Float64bits(n)) + } + case String: + switch f.kind { + case reflect.String: + size = val.Len() + copy(buf, []byte(val.String())) + default: + // TODO: handle kind != bytes here + size = val.Len() + copy(buf, val.Bytes()) + } + case CustomType: + return val.Addr().Interface().(Custom).Pack(buf, options) + default: + panic(fmt.Sprintf("no pack handler for type: %s", typ)) + } + return +} + +func (f *Field) Pack(buf []byte, val reflect.Value, length int, options *Options) (int, error) { + typ := f.Type.Resolve(options) + if typ == Pad { + for i := 0; i < length; i++ { + buf[i] = 0 + } + return length, nil + } + if f.Slice { + // special case strings and byte slices for performance + end := val.Len() + if !f.Array && typ == Uint8 && (f.defType == Uint8 || f.kind == reflect.String) { + var tmp []byte + if f.kind == reflect.String { + tmp = []byte(val.String()) + } else { + tmp = val.Bytes() + } + copy(buf, tmp) + if end < length { + // TODO: allow configuring pad byte? + rep := bytes.Repeat([]byte{0}, length-end) + copy(buf[end:], rep) + return length, nil + } + return val.Len(), nil + } + pos := 0 + var zero reflect.Value + if end < length { + zero = reflect.Zero(val.Type().Elem()) + } + for i := 0; i < length; i++ { + cur := zero + if i < end { + cur = val.Index(i) + } + if n, err := f.packVal(buf[pos:], cur, 1, options); err != nil { + return pos, err + } else { + pos += n + } + } + return pos, nil + } else { + return f.packVal(buf, val, length, options) + } +} + +func (f *Field) unpackVal(buf []byte, val reflect.Value, length int, options *Options) error { + order := f.Order + if options.Order != nil { + order = options.Order + } + if f.Ptr { + val = val.Elem() + } + typ := f.Type.Resolve(options) + switch typ { + case Float32, Float64: + var n float64 + switch typ { + case Float32: + n = float64(math.Float32frombits(order.Uint32(buf))) + case Float64: + n = math.Float64frombits(order.Uint64(buf)) + } + switch f.kind { + case reflect.Float32, reflect.Float64: + val.SetFloat(n) + default: + return fmt.Errorf("struc: refusing to unpack float into field %s of type %s", f.Name, f.kind.String()) + } + case Bool, Int8, Int16, Int32, Int64, Uint8, Uint16, Uint32, Uint64: + var n uint64 + switch typ { + case Bool, Int8, Uint8: + n = uint64(buf[0]) + case Int16, Uint16: + n = uint64(order.Uint16(buf)) + case Int32, Uint32: + n = uint64(order.Uint32(buf)) + case Int64, Uint64: + n = uint64(order.Uint64(buf)) + } + switch f.kind { + case reflect.Bool: + val.SetBool(n != 0) + case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: + val.SetInt(int64(n)) + default: + val.SetUint(n) + } + default: + panic(fmt.Sprintf("no unpack handler for type: %s", typ)) + } + return nil +} + +func (f *Field) Unpack(buf []byte, val reflect.Value, length int, options *Options) error { + typ := f.Type.Resolve(options) + if typ == Pad || f.kind == reflect.String { + if typ == Pad { + return nil + } else { + val.SetString(string(buf)) + return nil + } + } else if f.Slice { + if val.Cap() < length { + val.Set(reflect.MakeSlice(val.Type(), length, length)) + } else if val.Len() < length { + val.Set(val.Slice(0, length)) + } + // special case byte slices for performance + if !f.Array && typ == Uint8 && f.defType == Uint8 { + copy(val.Bytes(), buf[:length]) + return nil + } + pos := 0 + size := typ.Size() + for i := 0; i < length; i++ { + if err := f.unpackVal(buf[pos:pos+size], val.Index(i), 1, options); err != nil { + return err + } + pos += size + } + return nil + } else { + return f.unpackVal(buf, val, length, options) + } +} |