From 1f5dbbbab170bc7f6dd2d47c7aface716ecb294c Mon Sep 17 00:00:00 2001 From: Luke Shumaker Date: Sun, 26 Jan 2020 14:11:07 -0500 Subject: wip --- rrdformat/rrdbinary/unmarshal.go | 240 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 240 insertions(+) create mode 100644 rrdformat/rrdbinary/unmarshal.go (limited to 'rrdformat/rrdbinary/unmarshal.go') diff --git a/rrdformat/rrdbinary/unmarshal.go b/rrdformat/rrdbinary/unmarshal.go new file mode 100644 index 0000000..be0b492 --- /dev/null +++ b/rrdformat/rrdbinary/unmarshal.go @@ -0,0 +1,240 @@ +package rrdbinary + +import ( + "bytes" + "fmt" + "math" + "reflect" + "strconv" + "strings" +) + +func Unmarshal(arch Architecture, data []byte, ptr interface{}) error { + ptrValue := reflect.ValueOf(ptr) + if ptrValue.Kind() != reflect.Ptr { + return typeErrorf("ptr is a %v, not a pointer", ptrValue.Kind()) + } + decoder := &unmarshaler{ + arch: arch, + pos: 0, + data: data, + } + return decoder.unmarshal(ptrValue, "") +} + +type unmarshaler struct { + arch Architecture + pos int + data []byte +} + +func (d *unmarshaler) binError(ctxLen int, msg string) error { + return newBinError(msg, d.data, d.pos, ctxLen) +} + +func (d *unmarshaler) binErrorf(ctxLen int, format string, a ...interface{}) error { + return d.binError(ctxLen, fmt.Sprintf(format, a...)) +} + +func (d *unmarshaler) unmarshal(v reflect.Value, tag string) error { + switch v.Type() { + case reflect.TypeOf(String("")): + return d.unmarshalString(v, tag) + case reflect.TypeOf(Float(0)): + return d.unmarshalFloat(v, tag) + case reflect.TypeOf(Uint(0)): + return d.unmarshalUint(v, tag) + case reflect.TypeOf(Unival(0)): + return d.unmarshalUnival(v, tag) + default: + switch v.Type().Kind() { + case reflect.Struct: + return d.unmarshalStruct(v, tag) + case reflect.Array: + return d.unmarshalArray(v, tag) + default: + return typeErrorf("invalid type for rrdbinary.Unmarshal: %v", v.Type()) + } + } +} + +func (d *unmarshaler) unmarshalStruct(v reflect.Value, tag string) error { + panicUnless(v.Kind() == reflect.Struct) + panicUnless(v.CanSet()) + + if tag != "" { + return typeErrorf("invalid rrdbinary struct tag for struct: %q", tag) + } + + for i := 0; i < v.NumField(); i++ { + fieldInfo := v.Type().Field(i) + tag := fieldInfo.Tag.Get("rrdbinary") + if tag == "-" { + continue + } + if err := d.unmarshal(v.Field(i), tag); err != nil { + return fmt.Errorf("field %s: %w", fieldInfo.Name, err) + } + } + return nil +} + +func (d *unmarshaler) unmarshalArray(v reflect.Value, tag string) error { + panicUnless(v.Kind() == reflect.Array) + panicUnless(v.CanSet()) + + for i := 0; i < v.Len(); i++ { + if err := d.unmarshal(v.Index(i), tag); err != nil { + return fmt.Errorf("index %d: %w", i, err) + } + } + return nil +} + +func (d *unmarshaler) unmarshalString(v reflect.Value, tag string) error { + panicUnless(v.Type() == reflect.TypeOf(String(""))) + panicUnless(v.CanSet()) + + size := 0 + switch { + case tag == "": + // do nothing + case strings.HasPrefix(tag, "size="): + var err error + size, err = strconv.Atoi(strings.TrimPrefix(tag, "size=")) + if err != nil { + return typeErrorf("invalid rrdbinary struct tag for string: %q", tag) + } + default: + return typeErrorf("invalid rrdbinary struct tag for string: %q", tag) + } + + data := d.data[d.pos:] + if size > 0 { + if len(data) < size { + return d.binErrorf(size, "unexpected end-of-file in %d-byte string", size) + } + data = data[:size] + } + + nul := bytes.IndexByte(data, 0) + if nul < 0 { + if size > 0 { + return d.binErrorf(size, "missing null-terminator on %d-byte string", size) + } else { + return d.binErrorf(16, "unexpected end-of-file looking for null-terminator on string") + } + } + + if size > 0 { + for _, byte := range data[nul:] { + if byte != 0 { + return d.binErrorf(size, "garbage data after null-terminator on fixed %d-byte string", size) + } + } + } else { + size = nul + 1 + } + + v.SetString(string(data[:nul])) + d.pos += size + return nil +} + +func (d *unmarshaler) unmarshalFloat(v reflect.Value, tag string) error { + panicUnless(v.Type() == reflect.TypeOf(Float(0))) + panicUnless(v.CanSet()) + + if d.arch.FloatWidth != 8 { + return archErrorf("rrdbinary does not support FloatWidth=%d; only supports 8", d.arch.FloatWidth) + } + if tag != "" { + return typeErrorf("invalid rrdbinary struct tag for float: %q", tag) + } + + data := d.data[d.pos:] + + padding := 0 + if d.pos%d.arch.FloatAlign != 0 { + padding = d.arch.FloatAlign - (d.pos % d.arch.FloatAlign) + } + if len(data) < padding { + return d.binErrorf(padding+d.arch.FloatWidth, "unexpected end-of-file in %d-byte padding-before-float", padding) + } + data = data[padding:] + + if len(data) < d.arch.FloatWidth { + return d.binErrorf(d.arch.FloatWidth, "unexpected end-of-file in %d-byte float", d.arch.FloatWidth) + } + + v.SetFloat(math.Float64frombits(d.arch.ByteOrder.Uint64(data))) + d.pos += padding + d.arch.FloatWidth + return nil +} + +func (d *unmarshaler) unmarshalUint(v reflect.Value, tag string) error { + panicUnless(v.Type() == reflect.TypeOf(Uint(0))) + panicUnless(v.CanSet()) + + if d.arch.UintWidth != 4 && d.arch.UintWidth != 8 { + return archErrorf("rrdbinary does not support UintWidth=%d; only supports 4 or 8", d.arch.UintWidth) + } + if tag != "" { + return typeErrorf("invalid rrdbinary struct tag for uint: %q", tag) + } + + data := d.data[d.pos:] + + padding := 0 + if d.pos%d.arch.UintAlign != 0 { + padding = d.arch.UintAlign - (d.pos % d.arch.UintAlign) + } + if len(data) < padding { + return d.binErrorf(padding+d.arch.UintWidth, "unexpected end-of-file in %d-byte padding-before-uint", padding) + } + data = data[padding:] + + if len(data) < d.arch.UintWidth { + return d.binErrorf(d.arch.UintWidth, "unexpected end-of-file in %d-byte uint", d.arch.UintWidth) + } + + switch d.arch.UintWidth { + case 4: + v.SetUint(uint64(d.arch.ByteOrder.Uint32(data))) + case 8: + v.SetUint(d.arch.ByteOrder.Uint64(data)) + } + d.pos += padding + d.arch.UintWidth + return nil +} + +func (d *unmarshaler) unmarshalUnival(v reflect.Value, tag string) error { + panicUnless(v.Type() == reflect.TypeOf(Unival(0))) + panicUnless(v.CanSet()) + + if d.arch.UnivalWidth != 8 { + return archErrorf("rrdbinary does not support UnivalWidth=%d; only supports 8", d.arch.UnivalWidth) + } + if tag != "" { + return typeErrorf("invalid rrdbinary struct tag for unival: %q", tag) + } + + data := d.data[d.pos:] + + padding := 0 + if d.pos%d.arch.UnivalAlign != 0 { + padding = d.arch.UnivalAlign - (d.pos % d.arch.UnivalAlign) + } + if len(data) < padding { + return d.binErrorf(padding+d.arch.UnivalWidth, "unexpected end-of-file in %d-byte padding-before-unival", padding) + } + data = data[padding:] + + if len(data) < d.arch.UnivalWidth { + return d.binErrorf(d.arch.UnivalWidth, "unexpected end-of-file in %d-byte unival", d.arch.UnivalWidth) + } + + v.SetUint(d.arch.ByteOrder.Uint64(data)) + d.pos += padding + d.arch.UnivalWidth + return nil +} -- cgit v1.2.3