mirror of https://github.com/dsoprea/go-exif.git
311 lines
9.1 KiB
Go
311 lines
9.1 KiB
Go
package exif
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import (
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"errors"
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"fmt"
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"strconv"
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"strings"
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"encoding/binary"
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"github.com/dsoprea/go-logging"
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)
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type TagTypePrimitive uint16
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func (typeType TagTypePrimitive) String() string {
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return TypeNames[typeType]
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}
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func (tagType TagTypePrimitive) Size() int {
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if tagType == TypeByte {
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return 1
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} else if tagType == TypeAscii || tagType == TypeAsciiNoNul {
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return 1
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} else if tagType == TypeShort {
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return 2
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} else if tagType == TypeLong {
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return 4
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} else if tagType == TypeRational {
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return 8
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} else if tagType == TypeSignedLong {
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return 4
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} else if tagType == TypeSignedRational {
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return 8
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} else {
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log.Panicf("can not determine tag-value size for type (%d): [%s]", tagType, TypeNames[tagType])
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// Never called.
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return 0
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}
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}
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const (
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TypeByte TagTypePrimitive = 1
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TypeAscii TagTypePrimitive = 2
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TypeShort TagTypePrimitive = 3
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TypeLong TagTypePrimitive = 4
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TypeRational TagTypePrimitive = 5
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TypeUndefined TagTypePrimitive = 7
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TypeSignedLong TagTypePrimitive = 9
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TypeSignedRational TagTypePrimitive = 10
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// TypeAsciiNoNul is just a pseudo-type, for our own purposes.
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TypeAsciiNoNul TagTypePrimitive = 0xf0
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)
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var (
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typeLogger = log.NewLogger("exif.type")
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)
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var (
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// TODO(dustin): Rename TypeNames() to typeNames() and add getter.
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TypeNames = map[TagTypePrimitive]string{
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TypeByte: "BYTE",
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TypeAscii: "ASCII",
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TypeShort: "SHORT",
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TypeLong: "LONG",
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TypeRational: "RATIONAL",
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TypeUndefined: "UNDEFINED",
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TypeSignedLong: "SLONG",
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TypeSignedRational: "SRATIONAL",
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TypeAsciiNoNul: "_ASCII_NO_NUL",
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}
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TypeNamesR = map[string]TagTypePrimitive{}
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)
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var (
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// ErrNotEnoughData is used when there isn't enough data to accomodate what
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// we're trying to parse (sizeof(type) * unit_count).
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ErrNotEnoughData = errors.New("not enough data for type")
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// ErrWrongType is used when we try to parse anything other than the
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// current type.
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ErrWrongType = errors.New("wrong type, can not parse")
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// ErrUnhandledUnknownTag is used when we try to parse a tag that's
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// recorded as an "unknown" type but not a documented tag (therefore
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// leaving us not knowning how to read it).
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ErrUnhandledUnknownTypedTag = errors.New("not a standard unknown-typed tag")
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)
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type Rational struct {
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Numerator uint32
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Denominator uint32
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}
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type SignedRational struct {
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Numerator int32
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Denominator int32
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}
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func TagTypeSize(tagType TagTypePrimitive) int {
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// DEPRECATED(dustin): `(TagTypePrimitive).Size()` should be used, directly.
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return tagType.Size()
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}
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// Format returns a stringified value for the given bytes. Automatically
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// calculates count based on type size.
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func Format(rawBytes []byte, tagType TagTypePrimitive, justFirst bool, byteOrder binary.ByteOrder) (value string, err error) {
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defer func() {
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if state := recover(); state != nil {
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err = log.Wrap(state.(error))
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}
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}()
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// TODO(dustin): !! Add tests
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typeSize := tagType.Size()
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if len(rawBytes)%typeSize != 0 {
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log.Panicf("byte-count (%d) does not align for [%s] type with a size of (%d) bytes", len(rawBytes), TypeNames[tagType], typeSize)
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}
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// unitCount is the calculated unit-count. This should equal the original
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// value from the tag (pre-resolution).
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unitCount := uint32(len(rawBytes) / typeSize)
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// Truncate the items if it's not bytes or a string and we just want the first.
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valueSuffix := ""
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if justFirst == true && unitCount > 1 && tagType != TypeByte && tagType != TypeAscii && tagType != TypeAsciiNoNul {
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unitCount = 1
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valueSuffix = "..."
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}
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if tagType == TypeByte {
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items, err := parser.ParseBytes(rawBytes, unitCount)
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log.PanicIf(err)
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return DumpBytesToString(items), nil
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} else if tagType == TypeAscii {
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phrase, err := parser.ParseAscii(rawBytes, unitCount)
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log.PanicIf(err)
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return phrase, nil
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} else if tagType == TypeAsciiNoNul {
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phrase, err := parser.ParseAsciiNoNul(rawBytes, unitCount)
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log.PanicIf(err)
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return phrase, nil
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} else if tagType == TypeShort {
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items, err := parser.ParseShorts(rawBytes, unitCount, byteOrder)
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log.PanicIf(err)
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if len(items) > 0 {
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if justFirst == true {
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return fmt.Sprintf("%v%s", items[0], valueSuffix), nil
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} else {
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return fmt.Sprintf("%v", items), nil
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}
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} else {
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return "", nil
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}
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} else if tagType == TypeLong {
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items, err := parser.ParseLongs(rawBytes, unitCount, byteOrder)
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log.PanicIf(err)
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if len(items) > 0 {
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if justFirst == true {
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return fmt.Sprintf("%v%s", items[0], valueSuffix), nil
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} else {
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return fmt.Sprintf("%v", items), nil
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}
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} else {
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return "", nil
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}
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} else if tagType == TypeRational {
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items, err := parser.ParseRationals(rawBytes, unitCount, byteOrder)
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log.PanicIf(err)
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if len(items) > 0 {
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parts := make([]string, len(items))
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for i, r := range items {
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parts[i] = fmt.Sprintf("%d/%d", r.Numerator, r.Denominator)
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}
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if justFirst == true {
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return fmt.Sprintf("%v%s", parts[0], valueSuffix), nil
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} else {
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return fmt.Sprintf("%v", parts), nil
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}
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} else {
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return "", nil
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}
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} else if tagType == TypeSignedLong {
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items, err := parser.ParseSignedLongs(rawBytes, unitCount, byteOrder)
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log.PanicIf(err)
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if len(items) > 0 {
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if justFirst == true {
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return fmt.Sprintf("%v%s", items[0], valueSuffix), nil
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} else {
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return fmt.Sprintf("%v", items), nil
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}
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} else {
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return "", nil
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}
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} else if tagType == TypeSignedRational {
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items, err := parser.ParseSignedRationals(rawBytes, unitCount, byteOrder)
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log.PanicIf(err)
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parts := make([]string, len(items))
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for i, r := range items {
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parts[i] = fmt.Sprintf("%d/%d", r.Numerator, r.Denominator)
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}
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if len(items) > 0 {
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if justFirst == true {
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return fmt.Sprintf("%v%s", parts[0], valueSuffix), nil
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} else {
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return fmt.Sprintf("%v", parts), nil
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}
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} else {
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return "", nil
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}
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} else {
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// Affects only "unknown" values, in general.
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log.Panicf("value of type [%s] can not be formatted into string", tagType.String())
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// Never called.
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return "", nil
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}
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}
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func EncodeStringToBytes(tagType TagTypePrimitive, valueString string) (value interface{}, err error) {
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defer func() {
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if state := recover(); state != nil {
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err = log.Wrap(state.(error))
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}
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}()
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if tagType == TypeUndefined {
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// TODO(dustin): Circle back to this.
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log.Panicf("undefined-type values are not supported")
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}
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if tagType == TypeByte {
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return []byte(valueString), nil
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} else if tagType == TypeAscii || tagType == TypeAsciiNoNul {
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// Whether or not we're putting an NUL on the end is only relevant for
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// byte-level encoding. This function really just supports a user
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// interface.
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return valueString, nil
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} else if tagType == TypeShort {
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n, err := strconv.ParseUint(valueString, 10, 16)
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log.PanicIf(err)
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return uint16(n), nil
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} else if tagType == TypeLong {
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n, err := strconv.ParseUint(valueString, 10, 32)
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log.PanicIf(err)
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return uint32(n), nil
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} else if tagType == TypeRational {
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parts := strings.SplitN(valueString, "/", 2)
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numerator, err := strconv.ParseUint(parts[0], 10, 32)
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log.PanicIf(err)
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denominator, err := strconv.ParseUint(parts[1], 10, 32)
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log.PanicIf(err)
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return Rational{
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Numerator: uint32(numerator),
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Denominator: uint32(denominator),
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}, nil
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} else if tagType == TypeSignedLong {
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n, err := strconv.ParseInt(valueString, 10, 32)
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log.PanicIf(err)
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return int32(n), nil
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} else if tagType == TypeSignedRational {
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parts := strings.SplitN(valueString, "/", 2)
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numerator, err := strconv.ParseInt(parts[0], 10, 32)
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log.PanicIf(err)
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denominator, err := strconv.ParseInt(parts[1], 10, 32)
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log.PanicIf(err)
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return SignedRational{
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Numerator: int32(numerator),
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Denominator: int32(denominator),
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}, nil
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}
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log.Panicf("from-string encoding for type not supported; this shouldn't happen: [%s]", tagType.String())
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return nil, nil
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}
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func init() {
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for typeId, typeName := range TypeNames {
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TypeNamesR[typeName] = typeId
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}
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}
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