Exemplo n.º 1
0
// Parse decodes all Nikon makernote data found in x and adds it to x.
func (_ *nikonV3) Parse(x *exif.Exif) error {
	m, err := x.Get(exif.MakerNote)
	if err != nil {
		return nil
	} else if bytes.Compare(m.Val[:6], []byte("Nikon\000")) != 0 {
		return nil
	}

	// Nikon v3 maker note is a self-contained IFD (offsets are relative
	// to the start of the maker note)
	mkNotes, err := tiff.Decode(bytes.NewReader(m.Val[10:]))
	if err != nil {
		return err
	}
	x.LoadTags(mkNotes.Dirs[0], makerNoteNikon3Fields, false)
	return nil
}
Exemplo n.º 2
0
// Decode parses EXIF-encoded data from r and returns a queryable Exif
// object. After the exif data section is called and the tiff structure
// decoded, each registered parser is called (in order of registration). If
// one parser returns an error, decoding terminates and the remaining
// parsers are not called.
// The error can be inspected with functions such as IsCriticalError to
// determine whether the returned object might still be usable.
func Decode(r io.Reader) (*Exif, error) {
	// EXIF data in JPEG is stored in the APP1 marker. EXIF data uses the TIFF
	// format to store data.
	// If we're parsing a TIFF image, we don't need to strip away any data.
	// If we're parsing a JPEG image, we need to strip away the JPEG APP1
	// marker and also the EXIF header.

	header := make([]byte, 4)
	n, err := r.Read(header)
	if err != nil {
		return nil, err
	}
	if n < len(header) {
		return nil, errors.New("exif: short read on header")
	}

	var isTiff bool
	switch string(header) {
	case "II*\x00":
		// TIFF - Little endian (Intel)
		isTiff = true
	case "MM\x00*":
		// TIFF - Big endian (Motorola)
		isTiff = true
	default:
		// Not TIFF, assume JPEG
	}

	// Put the header bytes back into the reader.
	r = io.MultiReader(bytes.NewReader(header), r)
	var (
		er  *bytes.Reader
		tif *tiff.Tiff
	)

	if isTiff {
		// Functions below need the IFDs from the TIFF data to be stored in a
		// *bytes.Reader.  We use TeeReader to get a copy of the bytes as a
		// side-effect of tiff.Decode() doing its work.
		b := &bytes.Buffer{}
		tr := io.TeeReader(r, b)
		tif, err = tiff.Decode(tr)
		er = bytes.NewReader(b.Bytes())
	} else {
		// Locate the JPEG APP1 header.
		var sec *appSec
		sec, err = newAppSec(jpeg_APP1, r)
		if err != nil {
			return nil, err
		}
		// Strip away EXIF header.
		er, err = sec.exifReader()
		if err != nil {
			return nil, err
		}
		tif, err = tiff.Decode(er)
	}

	if err != nil {
		return nil, fmt.Errorf("exif: decode failed (%v) ", err)
	}

	er.Seek(0, 0)
	raw, err := ioutil.ReadAll(er)
	if err != nil {
		return nil, fmt.Errorf("exif: decode failed (%v) ", err)
	}

	// build an exif structure from the tiff
	x := &Exif{
		main: map[FieldName]*tiff.Tag{},
		Tiff: tif,
		Raw:  raw,
	}

	for i, p := range parsers {
		if err := p.Parse(x); err != nil {
			if _, ok := err.(tiffErrors); ok {
				return x, err
			}
			// This should never happen, as Parse always returns a tiffError
			// for now, but that could change.
			return x, fmt.Errorf("exif: parser %v failed (%v)", i, err)
		}
	}

	return x, nil
}