gotosocial/vendor/github.com/dsoprea/go-exif/ifd_enumerate.go

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package exif
import (
"bytes"
"errors"
"fmt"
"reflect"
"strconv"
"strings"
"time"
"encoding/binary"
"github.com/dsoprea/go-logging"
)
var (
ifdEnumerateLogger = log.NewLogger("exifjpeg.ifd")
)
var (
ErrNoThumbnail = errors.New("no thumbnail")
ErrNoGpsTags = errors.New("no gps tags")
ErrTagTypeNotValid = errors.New("tag type invalid")
)
var (
ValidGpsVersions = [][4]byte{
{2, 2, 0, 0},
// Suddenly appeared at the default in 2.31: https://home.jeita.or.jp/tsc/std-pdf/CP-3451D.pdf
//
// Note that the presence of 2.3.0.0 doesn't seem to guarantee
// coordinates. In some cases, we seen just the following:
//
// GPS Tag Version |2.3.0.0
// GPS Receiver Status |V
// Geodetic Survey Data|WGS-84
// GPS Differential Cor|0
//
{2, 3, 0, 0},
}
)
// IfdTagEnumerator knows how to decode an IFD and all of the tags it
// describes.
//
// The IFDs and the actual values can float throughout the EXIF block, but the
// IFD itself is just a minor header followed by a set of repeating,
// statically-sized records. So, the tags (though notnecessarily their values)
// are fairly simple to enumerate.
type IfdTagEnumerator struct {
byteOrder binary.ByteOrder
addressableData []byte
ifdOffset uint32
buffer *bytes.Buffer
}
func NewIfdTagEnumerator(addressableData []byte, byteOrder binary.ByteOrder, ifdOffset uint32) (ite *IfdTagEnumerator) {
ite = &IfdTagEnumerator{
addressableData: addressableData,
byteOrder: byteOrder,
buffer: bytes.NewBuffer(addressableData[ifdOffset:]),
}
return ite
}
// getUint16 reads a uint16 and advances both our current and our current
// accumulator (which allows us to know how far to seek to the beginning of the
// next IFD when it's time to jump).
func (ife *IfdTagEnumerator) getUint16() (value uint16, raw []byte, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
needBytes := 2
offset := 0
raw = make([]byte, needBytes)
for offset < needBytes {
n, err := ife.buffer.Read(raw[offset:])
log.PanicIf(err)
offset += n
}
value = ife.byteOrder.Uint16(raw)
return value, raw, nil
}
// getUint32 reads a uint32 and advances both our current and our current
// accumulator (which allows us to know how far to seek to the beginning of the
// next IFD when it's time to jump).
func (ife *IfdTagEnumerator) getUint32() (value uint32, raw []byte, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
needBytes := 4
offset := 0
raw = make([]byte, needBytes)
for offset < needBytes {
n, err := ife.buffer.Read(raw[offset:])
log.PanicIf(err)
offset += n
}
value = ife.byteOrder.Uint32(raw)
return value, raw, nil
}
type IfdEnumerate struct {
exifData []byte
buffer *bytes.Buffer
byteOrder binary.ByteOrder
currentOffset uint32
tagIndex *TagIndex
ifdMapping *IfdMapping
}
func NewIfdEnumerate(ifdMapping *IfdMapping, tagIndex *TagIndex, exifData []byte, byteOrder binary.ByteOrder) *IfdEnumerate {
return &IfdEnumerate{
exifData: exifData,
buffer: bytes.NewBuffer(exifData),
byteOrder: byteOrder,
ifdMapping: ifdMapping,
tagIndex: tagIndex,
}
}
func (ie *IfdEnumerate) getTagEnumerator(ifdOffset uint32) (ite *IfdTagEnumerator) {
ite = NewIfdTagEnumerator(
ie.exifData[ExifAddressableAreaStart:],
ie.byteOrder,
ifdOffset)
return ite
}
func (ie *IfdEnumerate) parseTag(fqIfdPath string, tagPosition int, ite *IfdTagEnumerator, resolveValue bool) (tag *IfdTagEntry, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
tagId, _, err := ite.getUint16()
log.PanicIf(err)
tagTypeRaw, _, err := ite.getUint16()
log.PanicIf(err)
tagType := TagTypePrimitive(tagTypeRaw)
unitCount, _, err := ite.getUint32()
log.PanicIf(err)
valueOffset, rawValueOffset, err := ite.getUint32()
log.PanicIf(err)
if _, found := TypeNames[tagType]; found == false {
log.Panic(ErrTagTypeNotValid)
}
ifdPath, err := ie.ifdMapping.StripPathPhraseIndices(fqIfdPath)
log.PanicIf(err)
tag = &IfdTagEntry{
IfdPath: ifdPath,
TagId: tagId,
TagIndex: tagPosition,
TagType: tagType,
UnitCount: unitCount,
ValueOffset: valueOffset,
RawValueOffset: rawValueOffset,
}
if resolveValue == true {
value, isUnhandledUnknown, err := ie.resolveTagValue(tag)
log.PanicIf(err)
tag.value = value
tag.isUnhandledUnknown = isUnhandledUnknown
}
// If it's an IFD but not a standard one, it'll just be seen as a LONG
// (the standard IFD tag type), later, unless we skip it because it's
// [likely] not even in the standard list of known tags.
mi, err := ie.ifdMapping.GetChild(ifdPath, tagId)
if err == nil {
tag.ChildIfdName = mi.Name
tag.ChildIfdPath = mi.PathPhrase()
tag.ChildFqIfdPath = fmt.Sprintf("%s/%s", fqIfdPath, mi.Name)
// We also need to set `tag.ChildFqIfdPath` but can't do it here
// because we don't have the IFD index.
} else if log.Is(err, ErrChildIfdNotMapped) == false {
log.Panic(err)
}
return tag, nil
}
func (ie *IfdEnumerate) GetValueContext(ite *IfdTagEntry) *ValueContext {
// TODO(dustin): Add test
addressableData := ie.exifData[ExifAddressableAreaStart:]
return newValueContextFromTag(
ite,
addressableData,
ie.byteOrder)
}
func (ie *IfdEnumerate) resolveTagValue(ite *IfdTagEntry) (valueBytes []byte, isUnhandledUnknown bool, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
addressableData := ie.exifData[ExifAddressableAreaStart:]
// Return the exact bytes of the unknown-type value. Returning a string
// (`ValueString`) is easy because we can just pass everything to
// `Sprintf()`. Returning the raw, typed value (`Value`) is easy
// (obviously). However, here, in order to produce the list of bytes, we
// need to coerce whatever `Undefined()` returns.
if ite.TagType == TypeUndefined {
valueContext := ie.GetValueContext(ite)
value, err := valueContext.Undefined()
if err != nil {
if err == ErrUnhandledUnknownTypedTag {
valueBytes = []byte(UnparseableUnknownTagValuePlaceholder)
return valueBytes, true, nil
}
log.Panic(err)
} else {
switch value.(type) {
case []byte:
return value.([]byte), false, nil
case TagUnknownType_UnknownValue:
b := []byte(value.(TagUnknownType_UnknownValue))
return b, false, nil
case string:
return []byte(value.(string)), false, nil
case UnknownTagValue:
valueBytes, err := value.(UnknownTagValue).ValueBytes()
log.PanicIf(err)
return valueBytes, false, nil
default:
// TODO(dustin): !! Finish translating the rest of the types (make reusable and replace into other similar implementations?)
log.Panicf("can not produce bytes for unknown-type tag (0x%04x) (1): [%s]", ite.TagId, reflect.TypeOf(value))
}
}
} else {
originalType := NewTagType(ite.TagType, ie.byteOrder)
byteCount := uint32(originalType.Type().Size()) * ite.UnitCount
tt := NewTagType(TypeByte, ie.byteOrder)
if tt.valueIsEmbedded(byteCount) == true {
iteLogger.Debugf(nil, "Reading BYTE value (ITE; embedded).")
// In this case, the bytes normally used for the offset are actually
// data.
valueBytes, err = tt.ParseBytes(ite.RawValueOffset, byteCount)
log.PanicIf(err)
} else {
iteLogger.Debugf(nil, "Reading BYTE value (ITE; at offset).")
valueBytes, err = tt.ParseBytes(addressableData[ite.ValueOffset:], byteCount)
log.PanicIf(err)
}
}
return valueBytes, false, nil
}
// RawTagVisitorPtr is an optional callback that can get hit for every tag we parse
// through. `addressableData` is the byte array startign after the EXIF header
// (where the offsets of all IFDs and values are calculated from).
//
// This was reimplemented as an interface to allow for simpler change management
// in the future.
type RawTagWalk interface {
Visit(fqIfdPath string, ifdIndex int, tagId uint16, tagType TagType, valueContext *ValueContext) (err error)
}
type RawTagWalkLegacyWrapper struct {
legacyVisitor RawTagVisitor
}
func (rtwlw RawTagWalkLegacyWrapper) Visit(fqIfdPath string, ifdIndex int, tagId uint16, tagType TagType, valueContext *ValueContext) (err error) {
return rtwlw.legacyVisitor(fqIfdPath, ifdIndex, tagId, tagType, *valueContext)
}
// RawTagVisitor is an optional callback that can get hit for every tag we parse
// through. `addressableData` is the byte array startign after the EXIF header
// (where the offsets of all IFDs and values are calculated from).
//
// DEPRECATED(dustin): Use a RawTagWalk instead.
type RawTagVisitor func(fqIfdPath string, ifdIndex int, tagId uint16, tagType TagType, valueContext ValueContext) (err error)
// ParseIfd decodes the IFD block that we're currently sitting on the first
// byte of.
func (ie *IfdEnumerate) ParseIfd(fqIfdPath string, ifdIndex int, ite *IfdTagEnumerator, visitor interface{}, doDescend bool, resolveValues bool) (nextIfdOffset uint32, entries []*IfdTagEntry, thumbnailData []byte, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
var visitorWrapper RawTagWalk
if visitor != nil {
var ok bool
visitorWrapper, ok = visitor.(RawTagWalk)
if ok == false {
// Legacy usage.
// `ok` can be `true` but `legacyVisitor` can still be `nil` (when
// passed as nil).
if legacyVisitor, ok := visitor.(RawTagVisitor); ok == true && legacyVisitor != nil {
visitorWrapper = RawTagWalkLegacyWrapper{
legacyVisitor: legacyVisitor,
}
}
}
}
tagCount, _, err := ite.getUint16()
log.PanicIf(err)
ifdEnumerateLogger.Debugf(nil, "Current IFD tag-count: (%d)", tagCount)
entries = make([]*IfdTagEntry, 0)
var iteThumbnailOffset *IfdTagEntry
var iteThumbnailSize *IfdTagEntry
for i := 0; i < int(tagCount); i++ {
tag, err := ie.parseTag(fqIfdPath, i, ite, resolveValues)
if err != nil {
if log.Is(err, ErrTagTypeNotValid) == true {
ifdEnumerateLogger.Warningf(nil, "Tag in IFD [%s] at position (%d) has invalid type and will be skipped.", fqIfdPath, i)
continue
}
log.Panic(err)
}
if tag.TagId == ThumbnailOffsetTagId {
iteThumbnailOffset = tag
continue
} else if tag.TagId == ThumbnailSizeTagId {
iteThumbnailSize = tag
continue
}
if visitorWrapper != nil {
tt := NewTagType(tag.TagType, ie.byteOrder)
valueContext := ie.GetValueContext(tag)
err := visitorWrapper.Visit(fqIfdPath, ifdIndex, tag.TagId, tt, valueContext)
log.PanicIf(err)
}
// If it's an IFD but not a standard one, it'll just be seen as a LONG
// (the standard IFD tag type), later, unless we skip it because it's
// [likely] not even in the standard list of known tags.
if tag.ChildIfdPath != "" {
if doDescend == true {
ifdEnumerateLogger.Debugf(nil, "Descending to IFD [%s].", tag.ChildIfdPath)
err := ie.scan(tag.ChildFqIfdPath, tag.ValueOffset, visitor, resolveValues)
log.PanicIf(err)
}
}
entries = append(entries, tag)
}
if iteThumbnailOffset != nil && iteThumbnailSize != nil {
thumbnailData, err = ie.parseThumbnail(iteThumbnailOffset, iteThumbnailSize)
log.PanicIf(err)
}
nextIfdOffset, _, err = ite.getUint32()
log.PanicIf(err)
ifdEnumerateLogger.Debugf(nil, "Next IFD at offset: (%08x)", nextIfdOffset)
return nextIfdOffset, entries, thumbnailData, nil
}
func (ie *IfdEnumerate) parseThumbnail(offsetIte, lengthIte *IfdTagEntry) (thumbnailData []byte, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
addressableData := ie.exifData[ExifAddressableAreaStart:]
vRaw, err := lengthIte.Value(addressableData, ie.byteOrder)
log.PanicIf(err)
vList := vRaw.([]uint32)
if len(vList) != 1 {
log.Panicf("not exactly one long: (%d)", len(vList))
}
length := vList[0]
// The tag is official a LONG type, but it's actually an offset to a blob of bytes.
offsetIte.TagType = TypeByte
offsetIte.UnitCount = length
thumbnailData, err = offsetIte.ValueBytes(addressableData, ie.byteOrder)
log.PanicIf(err)
return thumbnailData, nil
}
// Scan enumerates the different EXIF's IFD blocks.
func (ie *IfdEnumerate) scan(fqIfdName string, ifdOffset uint32, visitor interface{}, resolveValues bool) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
for ifdIndex := 0; ; ifdIndex++ {
ifdEnumerateLogger.Debugf(nil, "Parsing IFD [%s] (%d) at offset (%04x).", fqIfdName, ifdIndex, ifdOffset)
ite := ie.getTagEnumerator(ifdOffset)
nextIfdOffset, _, _, err := ie.ParseIfd(fqIfdName, ifdIndex, ite, visitor, true, resolveValues)
log.PanicIf(err)
if nextIfdOffset == 0 {
break
}
ifdOffset = nextIfdOffset
}
return nil
}
// Scan enumerates the different EXIF blocks (called IFDs). `rootIfdName` will
// be "IFD" in the TIFF standard.
func (ie *IfdEnumerate) Scan(rootIfdName string, ifdOffset uint32, visitor RawTagVisitor, resolveValue bool) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
err = ie.scan(rootIfdName, ifdOffset, visitor, resolveValue)
log.PanicIf(err)
return nil
}
// Ifd represents a single parsed IFD.
type Ifd struct {
// TODO(dustin): !! Why are all of these public? Privatize them and then add NextIfd().
// This is just for convenience, just so that we can easily get the values
// and not involve other projects in semantics that they won't otherwise
// need to know.
addressableData []byte
ByteOrder binary.ByteOrder
// Name is the name of the IFD (the rightmost name in the path, sans any
// indices).
Name string
// IfdPath is a simple IFD path (e.g. IFD/GPSInfo). No indices.
IfdPath string
// FqIfdPath is a fully-qualified IFD path (e.g. IFD0/GPSInfo0). With
// indices.
FqIfdPath string
TagId uint16
Id int
ParentIfd *Ifd
// ParentTagIndex is our tag position in the parent IFD, if we had a parent
// (if `ParentIfd` is not nil and we weren't an IFD referenced as a sibling
// instead of as a child).
ParentTagIndex int
// Name string
Index int
Offset uint32
Entries []*IfdTagEntry
EntriesByTagId map[uint16][]*IfdTagEntry
Children []*Ifd
ChildIfdIndex map[string]*Ifd
NextIfdOffset uint32
NextIfd *Ifd
thumbnailData []byte
ifdMapping *IfdMapping
tagIndex *TagIndex
}
func (ifd *Ifd) ChildWithIfdPath(ifdPath string) (childIfd *Ifd, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
for _, childIfd := range ifd.Children {
if childIfd.IfdPath == ifdPath {
return childIfd, nil
}
}
log.Panic(ErrTagNotFound)
return nil, nil
}
func (ifd *Ifd) TagValue(ite *IfdTagEntry) (value interface{}, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
value, err = ite.Value(ifd.addressableData, ifd.ByteOrder)
log.PanicIf(err)
return value, nil
}
func (ifd *Ifd) TagValueBytes(ite *IfdTagEntry) (value []byte, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
value, err = ite.ValueBytes(ifd.addressableData, ifd.ByteOrder)
log.PanicIf(err)
return value, nil
}
// FindTagWithId returns a list of tags (usually just zero or one) that match
// the given tag ID. This is efficient.
func (ifd *Ifd) FindTagWithId(tagId uint16) (results []*IfdTagEntry, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
results, found := ifd.EntriesByTagId[tagId]
if found != true {
log.Panic(ErrTagNotFound)
}
return results, nil
}
// FindTagWithName returns a list of tags (usually just zero or one) that match
// the given tag name. This is not efficient (though the labor is trivial).
func (ifd *Ifd) FindTagWithName(tagName string) (results []*IfdTagEntry, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
it, err := ifd.tagIndex.GetWithName(ifd.IfdPath, tagName)
if log.Is(err, ErrTagNotFound) == true {
log.Panic(ErrTagNotStandard)
} else if err != nil {
log.Panic(err)
}
results = make([]*IfdTagEntry, 0)
for _, ite := range ifd.Entries {
if ite.TagId == it.Id {
results = append(results, ite)
}
}
if len(results) == 0 {
log.Panic(ErrTagNotFound)
}
return results, nil
}
func (ifd Ifd) String() string {
parentOffset := uint32(0)
if ifd.ParentIfd != nil {
parentOffset = ifd.ParentIfd.Offset
}
return fmt.Sprintf("Ifd<ID=(%d) IFD-PATH=[%s] INDEX=(%d) COUNT=(%d) OFF=(0x%04x) CHILDREN=(%d) PARENT=(0x%04x) NEXT-IFD=(0x%04x)>", ifd.Id, ifd.IfdPath, ifd.Index, len(ifd.Entries), ifd.Offset, len(ifd.Children), parentOffset, ifd.NextIfdOffset)
}
func (ifd *Ifd) Thumbnail() (data []byte, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
if ifd.thumbnailData == nil {
log.Panic(ErrNoThumbnail)
}
return ifd.thumbnailData, nil
}
func (ifd *Ifd) dumpTags(tags []*IfdTagEntry) []*IfdTagEntry {
if tags == nil {
tags = make([]*IfdTagEntry, 0)
}
// Now, print the tags while also descending to child-IFDS as we encounter them.
ifdsFoundCount := 0
for _, tag := range ifd.Entries {
tags = append(tags, tag)
if tag.ChildIfdPath != "" {
ifdsFoundCount++
childIfd, found := ifd.ChildIfdIndex[tag.ChildIfdPath]
if found != true {
log.Panicf("alien child IFD referenced by a tag: [%s]", tag.ChildIfdPath)
}
tags = childIfd.dumpTags(tags)
}
}
if len(ifd.Children) != ifdsFoundCount {
log.Panicf("have one or more dangling child IFDs: (%d) != (%d)", len(ifd.Children), ifdsFoundCount)
}
if ifd.NextIfd != nil {
tags = ifd.NextIfd.dumpTags(tags)
}
return tags
}
// DumpTags prints the IFD hierarchy.
func (ifd *Ifd) DumpTags() []*IfdTagEntry {
return ifd.dumpTags(nil)
}
func (ifd *Ifd) printTagTree(populateValues bool, index, level int, nextLink bool) {
indent := strings.Repeat(" ", level*2)
prefix := " "
if nextLink {
prefix = ">"
}
fmt.Printf("%s%sIFD: %s\n", indent, prefix, ifd)
// Now, print the tags while also descending to child-IFDS as we encounter them.
ifdsFoundCount := 0
for _, tag := range ifd.Entries {
if tag.ChildIfdPath != "" {
fmt.Printf("%s - TAG: %s\n", indent, tag)
} else {
it, err := ifd.tagIndex.Get(ifd.IfdPath, tag.TagId)
tagName := ""
if err == nil {
tagName = it.Name
}
var value interface{}
if populateValues == true {
var err error
value, err = ifd.TagValue(tag)
if err != nil {
if err == ErrUnhandledUnknownTypedTag {
value = UnparseableUnknownTagValuePlaceholder
} else {
log.Panic(err)
}
}
}
fmt.Printf("%s - TAG: %s NAME=[%s] VALUE=[%v]\n", indent, tag, tagName, value)
}
if tag.ChildIfdPath != "" {
ifdsFoundCount++
childIfd, found := ifd.ChildIfdIndex[tag.ChildIfdPath]
if found != true {
log.Panicf("alien child IFD referenced by a tag: [%s]", tag.ChildIfdPath)
}
childIfd.printTagTree(populateValues, 0, level+1, false)
}
}
if len(ifd.Children) != ifdsFoundCount {
log.Panicf("have one or more dangling child IFDs: (%d) != (%d)", len(ifd.Children), ifdsFoundCount)
}
if ifd.NextIfd != nil {
ifd.NextIfd.printTagTree(populateValues, index+1, level, true)
}
}
// PrintTagTree prints the IFD hierarchy.
func (ifd *Ifd) PrintTagTree(populateValues bool) {
ifd.printTagTree(populateValues, 0, 0, false)
}
func (ifd *Ifd) printIfdTree(level int, nextLink bool) {
indent := strings.Repeat(" ", level*2)
prefix := " "
if nextLink {
prefix = ">"
}
fmt.Printf("%s%s%s\n", indent, prefix, ifd)
// Now, print the tags while also descending to child-IFDS as we encounter them.
ifdsFoundCount := 0
for _, tag := range ifd.Entries {
if tag.ChildIfdPath != "" {
ifdsFoundCount++
childIfd, found := ifd.ChildIfdIndex[tag.ChildIfdPath]
if found != true {
log.Panicf("alien child IFD referenced by a tag: [%s]", tag.ChildIfdPath)
}
childIfd.printIfdTree(level+1, false)
}
}
if len(ifd.Children) != ifdsFoundCount {
log.Panicf("have one or more dangling child IFDs: (%d) != (%d)", len(ifd.Children), ifdsFoundCount)
}
if ifd.NextIfd != nil {
ifd.NextIfd.printIfdTree(level, true)
}
}
// PrintIfdTree prints the IFD hierarchy.
func (ifd *Ifd) PrintIfdTree() {
ifd.printIfdTree(0, false)
}
func (ifd *Ifd) dumpTree(tagsDump []string, level int) []string {
if tagsDump == nil {
tagsDump = make([]string, 0)
}
indent := strings.Repeat(" ", level*2)
var ifdPhrase string
if ifd.ParentIfd != nil {
ifdPhrase = fmt.Sprintf("[%s]->[%s]:(%d)", ifd.ParentIfd.IfdPath, ifd.IfdPath, ifd.Index)
} else {
ifdPhrase = fmt.Sprintf("[ROOT]->[%s]:(%d)", ifd.IfdPath, ifd.Index)
}
startBlurb := fmt.Sprintf("%s> IFD %s TOP", indent, ifdPhrase)
tagsDump = append(tagsDump, startBlurb)
ifdsFoundCount := 0
for _, tag := range ifd.Entries {
tagsDump = append(tagsDump, fmt.Sprintf("%s - (0x%04x)", indent, tag.TagId))
if tag.ChildIfdPath != "" {
ifdsFoundCount++
childIfd, found := ifd.ChildIfdIndex[tag.ChildIfdPath]
if found != true {
log.Panicf("alien child IFD referenced by a tag: [%s]", tag.ChildIfdPath)
}
tagsDump = childIfd.dumpTree(tagsDump, level+1)
}
}
if len(ifd.Children) != ifdsFoundCount {
log.Panicf("have one or more dangling child IFDs: (%d) != (%d)", len(ifd.Children), ifdsFoundCount)
}
finishBlurb := fmt.Sprintf("%s< IFD %s BOTTOM", indent, ifdPhrase)
tagsDump = append(tagsDump, finishBlurb)
if ifd.NextIfd != nil {
siblingBlurb := fmt.Sprintf("%s* LINKING TO SIBLING IFD [%s]:(%d)", indent, ifd.NextIfd.IfdPath, ifd.NextIfd.Index)
tagsDump = append(tagsDump, siblingBlurb)
tagsDump = ifd.NextIfd.dumpTree(tagsDump, level)
}
return tagsDump
}
// DumpTree returns a list of strings describing the IFD hierarchy.
func (ifd *Ifd) DumpTree() []string {
return ifd.dumpTree(nil, 0)
}
// GpsInfo parses and consolidates the GPS info. This can only be called on the
// GPS IFD.
func (ifd *Ifd) GpsInfo() (gi *GpsInfo, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
// TODO(dustin): !! Also add functionality to update the GPS info.
gi = new(GpsInfo)
if ifd.IfdPath != IfdPathStandardGps {
log.Panicf("GPS can only be read on GPS IFD: [%s] != [%s]", ifd.IfdPath, IfdPathStandardGps)
}
if tags, found := ifd.EntriesByTagId[TagVersionId]; found == false {
// We've seen this. We'll just have to default to assuming we're in a
// 2.2.0.0 format.
ifdEnumerateLogger.Warningf(nil, "No GPS version tag (0x%04x) found.", TagVersionId)
} else {
hit := false
for _, acceptedGpsVersion := range ValidGpsVersions {
if bytes.Compare(tags[0].value, acceptedGpsVersion[:]) == 0 {
hit = true
break
}
}
if hit != true {
ifdEnumerateLogger.Warningf(nil, "GPS version not supported: %v", tags[0].value)
log.Panic(ErrNoGpsTags)
}
}
tags, found := ifd.EntriesByTagId[TagLatitudeId]
if found == false {
ifdEnumerateLogger.Warningf(nil, "latitude not found")
log.Panic(ErrNoGpsTags)
}
latitudeValue, err := ifd.TagValue(tags[0])
log.PanicIf(err)
// Look for whether North or South.
tags, found = ifd.EntriesByTagId[TagLatitudeRefId]
if found == false {
ifdEnumerateLogger.Warningf(nil, "latitude-ref not found")
log.Panic(ErrNoGpsTags)
}
latitudeRefValue, err := ifd.TagValue(tags[0])
log.PanicIf(err)
tags, found = ifd.EntriesByTagId[TagLongitudeId]
if found == false {
ifdEnumerateLogger.Warningf(nil, "longitude not found")
log.Panic(ErrNoGpsTags)
}
longitudeValue, err := ifd.TagValue(tags[0])
log.PanicIf(err)
// Look for whether West or East.
tags, found = ifd.EntriesByTagId[TagLongitudeRefId]
if found == false {
ifdEnumerateLogger.Warningf(nil, "longitude-ref not found")
log.Panic(ErrNoGpsTags)
}
longitudeRefValue, err := ifd.TagValue(tags[0])
log.PanicIf(err)
// Parse location.
latitudeRaw := latitudeValue.([]Rational)
gi.Latitude = GpsDegrees{
Orientation: latitudeRefValue.(string)[0],
Degrees: float64(latitudeRaw[0].Numerator) / float64(latitudeRaw[0].Denominator),
Minutes: float64(latitudeRaw[1].Numerator) / float64(latitudeRaw[1].Denominator),
Seconds: float64(latitudeRaw[2].Numerator) / float64(latitudeRaw[2].Denominator),
}
longitudeRaw := longitudeValue.([]Rational)
gi.Longitude = GpsDegrees{
Orientation: longitudeRefValue.(string)[0],
Degrees: float64(longitudeRaw[0].Numerator) / float64(longitudeRaw[0].Denominator),
Minutes: float64(longitudeRaw[1].Numerator) / float64(longitudeRaw[1].Denominator),
Seconds: float64(longitudeRaw[2].Numerator) / float64(longitudeRaw[2].Denominator),
}
// Parse altitude.
altitudeTags, foundAltitude := ifd.EntriesByTagId[TagAltitudeId]
altitudeRefTags, foundAltitudeRef := ifd.EntriesByTagId[TagAltitudeRefId]
if foundAltitude == true && foundAltitudeRef == true {
altitudeValue, err := ifd.TagValue(altitudeTags[0])
log.PanicIf(err)
altitudeRefValue, err := ifd.TagValue(altitudeRefTags[0])
log.PanicIf(err)
altitudeRaw := altitudeValue.([]Rational)
altitude := int(altitudeRaw[0].Numerator / altitudeRaw[0].Denominator)
if altitudeRefValue.([]byte)[0] == 1 {
altitude *= -1
}
gi.Altitude = altitude
}
// Parse time.
timestampTags, foundTimestamp := ifd.EntriesByTagId[TagTimestampId]
datestampTags, foundDatestamp := ifd.EntriesByTagId[TagDatestampId]
if foundTimestamp == true && foundDatestamp == true {
datestampValue, err := ifd.TagValue(datestampTags[0])
log.PanicIf(err)
dateParts := strings.Split(datestampValue.(string), ":")
year, err1 := strconv.ParseUint(dateParts[0], 10, 16)
month, err2 := strconv.ParseUint(dateParts[1], 10, 8)
day, err3 := strconv.ParseUint(dateParts[2], 10, 8)
if err1 == nil && err2 == nil && err3 == nil {
timestampValue, err := ifd.TagValue(timestampTags[0])
log.PanicIf(err)
timestampRaw := timestampValue.([]Rational)
hour := int(timestampRaw[0].Numerator / timestampRaw[0].Denominator)
minute := int(timestampRaw[1].Numerator / timestampRaw[1].Denominator)
second := int(timestampRaw[2].Numerator / timestampRaw[2].Denominator)
gi.Timestamp = time.Date(int(year), time.Month(month), int(day), hour, minute, second, 0, time.UTC)
}
}
return gi, nil
}
type ParsedTagVisitor func(*Ifd, *IfdTagEntry) error
func (ifd *Ifd) EnumerateTagsRecursively(visitor ParsedTagVisitor) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
for ptr := ifd; ptr != nil; ptr = ptr.NextIfd {
for _, ite := range ifd.Entries {
if ite.ChildIfdPath != "" {
childIfd := ifd.ChildIfdIndex[ite.ChildIfdPath]
err := childIfd.EnumerateTagsRecursively(visitor)
log.PanicIf(err)
} else {
err := visitor(ifd, ite)
log.PanicIf(err)
}
}
}
return nil
}
func (ifd *Ifd) GetValueContext(ite *IfdTagEntry) *ValueContext {
return newValueContextFromTag(
ite,
ifd.addressableData,
ifd.ByteOrder)
}
type QueuedIfd struct {
Name string
IfdPath string
FqIfdPath string
TagId uint16
Index int
Offset uint32
Parent *Ifd
// ParentTagIndex is our tag position in the parent IFD, if we had a parent
// (if `ParentIfd` is not nil and we weren't an IFD referenced as a sibling
// instead of as a child).
ParentTagIndex int
}
type IfdIndex struct {
RootIfd *Ifd
Ifds []*Ifd
Tree map[int]*Ifd
Lookup map[string][]*Ifd
}
// Scan enumerates the different EXIF blocks (called IFDs).
func (ie *IfdEnumerate) Collect(rootIfdOffset uint32, resolveValues bool) (index IfdIndex, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
tree := make(map[int]*Ifd)
ifds := make([]*Ifd, 0)
lookup := make(map[string][]*Ifd)
queue := []QueuedIfd{
{
Name: IfdStandard,
IfdPath: IfdStandard,
FqIfdPath: IfdStandard,
TagId: 0xffff,
Index: 0,
Offset: rootIfdOffset,
},
}
edges := make(map[uint32]*Ifd)
for {
if len(queue) == 0 {
break
}
qi := queue[0]
name := qi.Name
ifdPath := qi.IfdPath
fqIfdPath := qi.FqIfdPath
index := qi.Index
offset := qi.Offset
parentIfd := qi.Parent
queue = queue[1:]
ifdEnumerateLogger.Debugf(nil, "Parsing IFD [%s] (%d) at offset (%04x).", ifdPath, index, offset)
ite := ie.getTagEnumerator(offset)
nextIfdOffset, entries, thumbnailData, err := ie.ParseIfd(fqIfdPath, index, ite, nil, false, resolveValues)
log.PanicIf(err)
id := len(ifds)
entriesByTagId := make(map[uint16][]*IfdTagEntry)
for _, tag := range entries {
tags, found := entriesByTagId[tag.TagId]
if found == false {
tags = make([]*IfdTagEntry, 0)
}
entriesByTagId[tag.TagId] = append(tags, tag)
}
ifd := &Ifd{
addressableData: ie.exifData[ExifAddressableAreaStart:],
ByteOrder: ie.byteOrder,
Name: name,
IfdPath: ifdPath,
FqIfdPath: fqIfdPath,
TagId: qi.TagId,
Id: id,
ParentIfd: parentIfd,
ParentTagIndex: qi.ParentTagIndex,
Index: index,
Offset: offset,
Entries: entries,
EntriesByTagId: entriesByTagId,
// This is populated as each child is processed.
Children: make([]*Ifd, 0),
NextIfdOffset: nextIfdOffset,
thumbnailData: thumbnailData,
ifdMapping: ie.ifdMapping,
tagIndex: ie.tagIndex,
}
// Add ourselves to a big list of IFDs.
ifds = append(ifds, ifd)
// Install ourselves into a by-id lookup table (keys are unique).
tree[id] = ifd
// Install into by-name buckets.
if list_, found := lookup[ifdPath]; found == true {
lookup[ifdPath] = append(list_, ifd)
} else {
list_ = make([]*Ifd, 1)
list_[0] = ifd
lookup[ifdPath] = list_
}
// Add a link from the previous IFD in the chain to us.
if previousIfd, found := edges[offset]; found == true {
previousIfd.NextIfd = ifd
}
// Attach as a child to our parent (where we appeared as a tag in
// that IFD).
if parentIfd != nil {
parentIfd.Children = append(parentIfd.Children, ifd)
}
// Determine if any of our entries is a child IFD and queue it.
for i, entry := range entries {
if entry.ChildIfdPath == "" {
continue
}
qi := QueuedIfd{
Name: entry.ChildIfdName,
IfdPath: entry.ChildIfdPath,
FqIfdPath: entry.ChildFqIfdPath,
TagId: entry.TagId,
Index: 0,
Offset: entry.ValueOffset,
Parent: ifd,
ParentTagIndex: i,
}
queue = append(queue, qi)
}
// If there's another IFD in the chain.
if nextIfdOffset != 0 {
// Allow the next link to know what the previous link was.
edges[nextIfdOffset] = ifd
siblingIndex := index + 1
var fqIfdPath string
if parentIfd != nil {
fqIfdPath = fmt.Sprintf("%s/%s%d", parentIfd.FqIfdPath, name, siblingIndex)
} else {
fqIfdPath = fmt.Sprintf("%s%d", name, siblingIndex)
}
qi := QueuedIfd{
Name: name,
IfdPath: ifdPath,
FqIfdPath: fqIfdPath,
TagId: 0xffff,
Index: siblingIndex,
Offset: nextIfdOffset,
}
queue = append(queue, qi)
}
}
index.RootIfd = tree[0]
index.Ifds = ifds
index.Tree = tree
index.Lookup = lookup
err = ie.setChildrenIndex(index.RootIfd)
log.PanicIf(err)
return index, nil
}
func (ie *IfdEnumerate) setChildrenIndex(ifd *Ifd) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
childIfdIndex := make(map[string]*Ifd)
for _, childIfd := range ifd.Children {
childIfdIndex[childIfd.IfdPath] = childIfd
}
ifd.ChildIfdIndex = childIfdIndex
for _, childIfd := range ifd.Children {
err := ie.setChildrenIndex(childIfd)
log.PanicIf(err)
}
return nil
}
// ParseOneIfd is a hack to use an IE to parse a raw IFD block. Can be used for
// testing.
func ParseOneIfd(ifdMapping *IfdMapping, tagIndex *TagIndex, fqIfdPath, ifdPath string, byteOrder binary.ByteOrder, ifdBlock []byte, visitor RawTagVisitor, resolveValues bool) (nextIfdOffset uint32, entries []*IfdTagEntry, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
ie := NewIfdEnumerate(ifdMapping, tagIndex, make([]byte, 0), byteOrder)
ite := NewIfdTagEnumerator(ifdBlock, byteOrder, 0)
nextIfdOffset, entries, _, err = ie.ParseIfd(fqIfdPath, 0, ite, visitor, true, resolveValues)
log.PanicIf(err)
return nextIfdOffset, entries, nil
}
// ParseOneTag is a hack to use an IE to parse a raw tag block.
func ParseOneTag(ifdMapping *IfdMapping, tagIndex *TagIndex, fqIfdPath, ifdPath string, byteOrder binary.ByteOrder, tagBlock []byte, resolveValue bool) (tag *IfdTagEntry, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
ie := NewIfdEnumerate(ifdMapping, tagIndex, make([]byte, 0), byteOrder)
ite := NewIfdTagEnumerator(tagBlock, byteOrder, 0)
tag, err = ie.parseTag(fqIfdPath, 0, ite, resolveValue)
log.PanicIf(err)
return tag, nil
}
func FindIfdFromRootIfd(rootIfd *Ifd, ifdPath string) (ifd *Ifd, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
// TODO(dustin): !! Add test.
lineage, err := rootIfd.ifdMapping.ResolvePath(ifdPath)
log.PanicIf(err)
// Confirm the first IFD is our root IFD type, and then prune it because
// from then on we'll be searching down through our children.
if len(lineage) == 0 {
log.Panicf("IFD path must be non-empty.")
} else if lineage[0].Name != IfdStandard {
log.Panicf("First IFD path item must be [%s].", IfdStandard)
}
desiredRootIndex := lineage[0].Index
lineage = lineage[1:]
// TODO(dustin): !! This is a poorly conceived fix that just doubles the work we already have to do below, which then interacts badly with the indices not being properly represented in the IFD-phrase.
// TODO(dustin): !! <-- However, we're not sure whether we shouldn't store a secondary IFD-path with the indices. Some IFDs may not necessarily restrict which IFD indices they can be a child of (only the IFD itself matters). Validation should be delegated to the caller.
thisIfd := rootIfd
for currentRootIndex := 0; currentRootIndex < desiredRootIndex; currentRootIndex++ {
if thisIfd.NextIfd == nil {
log.Panicf("Root-IFD index (%d) does not exist in the data.", currentRootIndex)
}
thisIfd = thisIfd.NextIfd
}
for i, itii := range lineage {
var hit *Ifd
for _, childIfd := range thisIfd.Children {
if childIfd.TagId == itii.TagId {
hit = childIfd
break
}
}
// If we didn't find the child, add it.
if hit == nil {
log.Panicf("IFD [%s] in [%s] not found: %s", itii.Name, ifdPath, thisIfd.Children)
}
thisIfd = hit
// If we didn't find the sibling, add it.
for i = 0; i < itii.Index; i++ {
if thisIfd.NextIfd == nil {
log.Panicf("IFD [%s] does not have (%d) occurrences/siblings\n", thisIfd.IfdPath, itii.Index)
}
thisIfd = thisIfd.NextIfd
}
}
return thisIfd, nil
}