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

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package exif
import (
"errors"
"fmt"
"strings"
"github.com/dsoprea/go-logging"
)
const (
// IFD names. The paths that we referred to the IFDs with are comprised of
// these.
IfdStandard = "IFD"
IfdExif = "Exif"
IfdGps = "GPSInfo"
IfdIop = "Iop"
// Tag IDs for child IFDs.
IfdExifId = 0x8769
IfdGpsId = 0x8825
IfdIopId = 0xA005
// Just a placeholder.
IfdRootId = 0x0000
// The paths of the standard IFDs expressed in the standard IFD-mappings
// and as the group-names in the tag data.
IfdPathStandard = "IFD"
IfdPathStandardExif = "IFD/Exif"
IfdPathStandardExifIop = "IFD/Exif/Iop"
IfdPathStandardGps = "IFD/GPSInfo"
)
var (
ifdLogger = log.NewLogger("exif.ifd")
)
var (
ErrChildIfdNotMapped = errors.New("no child-IFD for that tag-ID under parent")
)
// type IfdIdentity struct {
// ParentIfdName string
// IfdName string
// }
// func (ii IfdIdentity) String() string {
// return fmt.Sprintf("IfdIdentity<PARENT-NAME=[%s] NAME=[%s]>", ii.ParentIfdName, ii.IfdName)
// }
type MappedIfd struct {
ParentTagId uint16
Placement []uint16
Path []string
Name string
TagId uint16
Children map[uint16]*MappedIfd
}
func (mi *MappedIfd) String() string {
pathPhrase := mi.PathPhrase()
return fmt.Sprintf("MappedIfd<(0x%04X) [%s] PATH=[%s]>", mi.TagId, mi.Name, pathPhrase)
}
func (mi *MappedIfd) PathPhrase() string {
return strings.Join(mi.Path, "/")
}
// IfdMapping describes all of the IFDs that we currently recognize.
type IfdMapping struct {
rootNode *MappedIfd
}
func NewIfdMapping() (ifdMapping *IfdMapping) {
rootNode := &MappedIfd{
Path: make([]string, 0),
Children: make(map[uint16]*MappedIfd),
}
return &IfdMapping{
rootNode: rootNode,
}
}
func NewIfdMappingWithStandard() (ifdMapping *IfdMapping) {
defer func() {
if state := recover(); state != nil {
err := log.Wrap(state.(error))
log.Panic(err)
}
}()
im := NewIfdMapping()
err := LoadStandardIfds(im)
log.PanicIf(err)
return im
}
func (im *IfdMapping) Get(parentPlacement []uint16) (childIfd *MappedIfd, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
ptr := im.rootNode
for _, tagId := range parentPlacement {
if descendantPtr, found := ptr.Children[tagId]; found == false {
log.Panicf("ifd child with tag-ID (%04x) not registered: [%s]", tagId, ptr.PathPhrase())
} else {
ptr = descendantPtr
}
}
return ptr, nil
}
func (im *IfdMapping) GetWithPath(pathPhrase string) (mi *MappedIfd, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
if pathPhrase == "" {
log.Panicf("path-phrase is empty")
}
path := strings.Split(pathPhrase, "/")
ptr := im.rootNode
for _, name := range path {
var hit *MappedIfd
for _, mi := range ptr.Children {
if mi.Name == name {
hit = mi
break
}
}
if hit == nil {
log.Panicf("ifd child with name [%s] not registered: [%s]", name, ptr.PathPhrase())
}
ptr = hit
}
return ptr, nil
}
// GetChild is a convenience function to get the child path for a given parent
// placement and child tag-ID.
func (im *IfdMapping) GetChild(parentPathPhrase string, tagId uint16) (mi *MappedIfd, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
mi, err = im.GetWithPath(parentPathPhrase)
log.PanicIf(err)
for _, childMi := range mi.Children {
if childMi.TagId == tagId {
return childMi, nil
}
}
// Whether or not an IFD is defined in data, such an IFD is not registered
// and would be unknown.
log.Panic(ErrChildIfdNotMapped)
return nil, nil
}
type IfdTagIdAndIndex struct {
Name string
TagId uint16
Index int
}
func (itii IfdTagIdAndIndex) String() string {
return fmt.Sprintf("IfdTagIdAndIndex<NAME=[%s] ID=(%04x) INDEX=(%d)>", itii.Name, itii.TagId, itii.Index)
}
// ResolvePath takes a list of names, which can also be suffixed with indices
// (to identify the second, third, etc.. sibling IFD) and returns a list of
// tag-IDs and those indices.
//
// Example:
//
// - IFD/Exif/Iop
// - IFD0/Exif/Iop
//
// This is the only call that supports adding the numeric indices.
func (im *IfdMapping) ResolvePath(pathPhrase string) (lineage []IfdTagIdAndIndex, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
pathPhrase = strings.TrimSpace(pathPhrase)
if pathPhrase == "" {
log.Panicf("can not resolve empty path-phrase")
}
path := strings.Split(pathPhrase, "/")
lineage = make([]IfdTagIdAndIndex, len(path))
ptr := im.rootNode
empty := IfdTagIdAndIndex{}
for i, name := range path {
indexByte := name[len(name)-1]
index := 0
if indexByte >= '0' && indexByte <= '9' {
index = int(indexByte - '0')
name = name[:len(name)-1]
}
itii := IfdTagIdAndIndex{}
for _, mi := range ptr.Children {
if mi.Name != name {
continue
}
itii.Name = name
itii.TagId = mi.TagId
itii.Index = index
ptr = mi
break
}
if itii == empty {
log.Panicf("ifd child with name [%s] not registered: [%s]", name, pathPhrase)
}
lineage[i] = itii
}
return lineage, nil
}
func (im *IfdMapping) FqPathPhraseFromLineage(lineage []IfdTagIdAndIndex) (fqPathPhrase string) {
fqPathParts := make([]string, len(lineage))
for i, itii := range lineage {
if itii.Index > 0 {
fqPathParts[i] = fmt.Sprintf("%s%d", itii.Name, itii.Index)
} else {
fqPathParts[i] = itii.Name
}
}
return strings.Join(fqPathParts, "/")
}
func (im *IfdMapping) PathPhraseFromLineage(lineage []IfdTagIdAndIndex) (pathPhrase string) {
pathParts := make([]string, len(lineage))
for i, itii := range lineage {
pathParts[i] = itii.Name
}
return strings.Join(pathParts, "/")
}
// StripPathPhraseIndices returns a non-fully-qualified path-phrase (no
// indices).
func (im *IfdMapping) StripPathPhraseIndices(pathPhrase string) (strippedPathPhrase string, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
lineage, err := im.ResolvePath(pathPhrase)
log.PanicIf(err)
strippedPathPhrase = im.PathPhraseFromLineage(lineage)
return strippedPathPhrase, nil
}
// Add puts the given IFD at the given position of the tree. The position of the
// tree is referred to as the placement and is represented by a set of tag-IDs,
// where the leftmost is the root tag and the tags going to the right are
// progressive descendants.
func (im *IfdMapping) Add(parentPlacement []uint16, tagId uint16, name string) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
// TODO(dustin): !! It would be nicer to provide a list of names in the placement rather than tag-IDs.
ptr, err := im.Get(parentPlacement)
log.PanicIf(err)
path := make([]string, len(parentPlacement)+1)
if len(parentPlacement) > 0 {
copy(path, ptr.Path)
}
path[len(path)-1] = name
placement := make([]uint16, len(parentPlacement)+1)
if len(placement) > 0 {
copy(placement, ptr.Placement)
}
placement[len(placement)-1] = tagId
childIfd := &MappedIfd{
ParentTagId: ptr.TagId,
Path: path,
Placement: placement,
Name: name,
TagId: tagId,
Children: make(map[uint16]*MappedIfd),
}
if _, found := ptr.Children[tagId]; found == true {
log.Panicf("child IFD with tag-ID (%04x) already registered under IFD [%s] with tag-ID (%04x)", tagId, ptr.Name, ptr.TagId)
}
ptr.Children[tagId] = childIfd
return nil
}
func (im *IfdMapping) dumpLineages(stack []*MappedIfd, input []string) (output []string, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
currentIfd := stack[len(stack)-1]
output = input
for _, childIfd := range currentIfd.Children {
stackCopy := make([]*MappedIfd, len(stack)+1)
copy(stackCopy, stack)
stackCopy[len(stack)] = childIfd
// Add to output, but don't include the obligatory root node.
parts := make([]string, len(stackCopy)-1)
for i, mi := range stackCopy[1:] {
parts[i] = mi.Name
}
output = append(output, strings.Join(parts, "/"))
output, err = im.dumpLineages(stackCopy, output)
log.PanicIf(err)
}
return output, nil
}
func (im *IfdMapping) DumpLineages() (output []string, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
stack := []*MappedIfd{im.rootNode}
output = make([]string, 0)
output, err = im.dumpLineages(stack, output)
log.PanicIf(err)
return output, nil
}
func LoadStandardIfds(im *IfdMapping) (err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
err = im.Add([]uint16{}, IfdRootId, IfdStandard)
log.PanicIf(err)
err = im.Add([]uint16{IfdRootId}, IfdExifId, IfdExif)
log.PanicIf(err)
err = im.Add([]uint16{IfdRootId, IfdExifId}, IfdIopId, IfdIop)
log.PanicIf(err)
err = im.Add([]uint16{IfdRootId}, IfdGpsId, IfdGps)
log.PanicIf(err)
return nil
}