GoToSocial/vendor/github.com/dsoprea/go-exif/v3/common/parser.go
2022-01-23 14:41:31 +01:00

281 lines
6.2 KiB
Go

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
}