use exif-terminator

vendor/github.com/dsoprea/go-exif/v3/common/parser.go

@@ -0,0 +1,280 @@
+package exifcommon
+
+import (
+	"bytes"
+	"errors"
+	"math"
+
+	"encoding/binary"
+
+	"github.com/dsoprea/go-logging"
+)
+
+var (
+	parserLogger = log.NewLogger("exifcommon.parser")
+)
+
+var (
+	ErrParseFail = errors.New("parse failure")
+)
+
+// Parser knows how to parse all well-defined, encoded EXIF types.
+type Parser struct {
+}
+
+// ParseBytesknows how to parse a byte-type value.
+func (p *Parser) ParseBytes(data []byte, unitCount uint32) (value []uint8, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeByte.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = []uint8(data[:count])
+
+	return value, nil
+}
+
+// ParseAscii returns a string and auto-strips the trailing NUL character that
+// should be at the end of the encoding.
+func (p *Parser) ParseAscii(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeAscii.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	if len(data) == 0 || data[count-1] != 0 {
+		s := string(data[:count])
+		parserLogger.Warningf(nil, "ASCII not terminated with NUL as expected: [%v]", s)
+
+		for i, c := range s {
+			if c > 127 {
+				// Binary
+
+				t := s[:i]
+				parserLogger.Warningf(nil, "ASCII also had binary characters. Truncating: [%v]->[%s]", s, t)
+
+				return t, nil
+			}
+		}
+
+		return s, nil
+	}
+
+	// Auto-strip the NUL from the end. It serves no purpose outside of
+	// encoding semantics.
+
+	return string(data[:count-1]), nil
+}
+
+// ParseAsciiNoNul returns a string without any consideration for a trailing NUL
+// character.
+func (p *Parser) ParseAsciiNoNul(data []byte, unitCount uint32) (value string, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeAscii.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	return string(data[:count]), nil
+}
+
+// ParseShorts knows how to parse an encoded list of shorts.
+func (p *Parser) ParseShorts(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []uint16, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeShort.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]uint16, count)
+	for i := 0; i < count; i++ {
+		value[i] = byteOrder.Uint16(data[i*2:])
+	}
+
+	return value, nil
+}
+
+// ParseLongs knows how to encode an encoded list of unsigned longs.
+func (p *Parser) ParseLongs(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []uint32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeLong.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]uint32, count)
+	for i := 0; i < count; i++ {
+		value[i] = byteOrder.Uint32(data[i*4:])
+	}
+
+	return value, nil
+}
+
+// ParseFloats knows how to encode an encoded list of floats.
+func (p *Parser) ParseFloats(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []float32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) != (TypeFloat.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]float32, count)
+	for i := 0; i < count; i++ {
+		value[i] = math.Float32frombits(byteOrder.Uint32(data[i*4 : (i+1)*4]))
+	}
+
+	return value, nil
+}
+
+// ParseDoubles knows how to encode an encoded list of doubles.
+func (p *Parser) ParseDoubles(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []float64, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	count := int(unitCount)
+
+	if len(data) != (TypeDouble.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]float64, count)
+	for i := 0; i < count; i++ {
+		value[i] = math.Float64frombits(byteOrder.Uint64(data[i*8 : (i+1)*8]))
+	}
+
+	return value, nil
+}
+
+// ParseRationals knows how to parse an encoded list of unsigned rationals.
+func (p *Parser) ParseRationals(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []Rational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeRational.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	value = make([]Rational, count)
+	for i := 0; i < count; i++ {
+		value[i].Numerator = byteOrder.Uint32(data[i*8:])
+		value[i].Denominator = byteOrder.Uint32(data[i*8+4:])
+	}
+
+	return value, nil
+}
+
+// ParseSignedLongs knows how to parse an encoded list of signed longs.
+func (p *Parser) ParseSignedLongs(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []int32, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeSignedLong.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	b := bytes.NewBuffer(data)
+
+	value = make([]int32, count)
+	for i := 0; i < count; i++ {
+		err := binary.Read(b, byteOrder, &value[i])
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}
+
+// ParseSignedRationals knows how to parse an encoded list of signed
+// rationals.
+func (p *Parser) ParseSignedRationals(data []byte, unitCount uint32, byteOrder binary.ByteOrder) (value []SignedRational, err error) {
+	defer func() {
+		if state := recover(); state != nil {
+			err = log.Wrap(state.(error))
+		}
+	}()
+
+	// TODO(dustin): Add test
+
+	count := int(unitCount)
+
+	if len(data) < (TypeSignedRational.Size() * count) {
+		log.Panic(ErrNotEnoughData)
+	}
+
+	b := bytes.NewBuffer(data)
+
+	value = make([]SignedRational, count)
+	for i := 0; i < count; i++ {
+		err = binary.Read(b, byteOrder, &value[i].Numerator)
+		log.PanicIf(err)
+
+		err = binary.Read(b, byteOrder, &value[i].Denominator)
+		log.PanicIf(err)
+	}
+
+	return value, nil
+}