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ifd_enumerate.go: Add missing comments

dustin/add_skipped_tags_tracking
Dustin Oprea 2020-05-18 00:50:10 -04:00
parent 6629fe3012
commit 7aa41d6d0d
1 changed files with 23 additions and 3 deletions
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26
v2/ifd_enumerate.go
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@ -35,6 +35,7 @@ var (
)
var (
// ValidGpsVersions is the list of recognized EXIF GPS versions/signatures.
ValidGpsVersions = [][4]byte{
// 2.0.0.0 appears to have a very similar format to 2.2.0.0, so enabling
// it under that assumption.
@ -163,6 +164,8 @@ func (bp *byteParser) CurrentOffset() uint32 {
return bp.currentOffset
}
// IfdEnumerate is the main enumeration type. It knows how to parse the IFD
// containers in the EXIF blob.
type IfdEnumerate struct {
exifData []byte
buffer *bytes.Buffer
@ -172,6 +175,7 @@ type IfdEnumerate struct {
furthestOffset uint32
}
// NewIfdEnumerate returns a new instance of IfdEnumerate.
func NewIfdEnumerate(ifdMapping *IfdMapping, tagIndex *TagIndex, exifData []byte, byteOrder binary.ByteOrder) *IfdEnumerate {
return &IfdEnumerate{
exifData: exifData,
@ -446,7 +450,8 @@ func (ie *IfdEnumerate) parseThumbnail(offsetIte, lengthIte *IfdTagEntry) (thumb
return thumbnailData, nil
}
// scan enumerates the different IFD blocks.
// scan parses and enumerates the different IFD blocks out of a byte-slice and
// invokes a visitor callback along the way. No information is kept or returned.
func (ie *IfdEnumerate) scan(ifdName string, ifdOffset uint32, visitor TagVisitorFn) (err error) {
defer func() {
if state := recover(); state != nil {
@ -506,7 +511,7 @@ func (ie *IfdEnumerate) Scan(rootIfdName string, ifdOffset uint32, visitor TagVi
return nil
}
// Ifd represents a single parsed IFD.
// Ifd represents a single, parsed IFD.
type Ifd struct {
// TODO(dustin): !! Why are all of these exported? Stop doing this in the next release.
@ -556,6 +561,8 @@ type Ifd struct {
tagIndex *TagIndex
}
// ChildWithIfdPath returns an `Ifd` struct for the given child of the current
// IFD.
func (ifd *Ifd) ChildWithIfdPath(ifdPath string) (childIfd *Ifd, err error) {
defer func() {
if state := recover(); state != nil {
@ -620,6 +627,7 @@ func (ifd *Ifd) FindTagWithName(tagName string) (results []*IfdTagEntry, err err
return results, nil
}
// String returns a description string.
func (ifd *Ifd) String() string {
parentOffset := uint32(0)
if ifd.ParentIfd != nil {
@ -629,6 +637,8 @@ func (ifd *Ifd) String() string {
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)
}
// Thumbnail returns the raw thumbnail bytes. This is typically directly
// readable by any standard image viewer.
func (ifd *Ifd) Thumbnail() (data []byte, err error) {
if ifd.thumbnailData == nil {
@ -1000,8 +1010,12 @@ func (ifd *Ifd) GpsInfo() (gi *GpsInfo, err error) {
return gi, nil
}
// ParsedTagVisitor is a callback used if wanting to visit through all tags and
// child IFDs from the current IFD and going down.
type ParsedTagVisitor func(*Ifd, *IfdTagEntry) error
// EnumerateTagsRecursively calls the given visitor function for every tag and
// IFD in the current IFD, recursively.
func (ifd *Ifd) EnumerateTagsRecursively(visitor ParsedTagVisitor) (err error) {
defer func() {
if state := recover(); state != nil {
@ -1027,6 +1041,7 @@ func (ifd *Ifd) EnumerateTagsRecursively(visitor ParsedTagVisitor) (err error) {
return nil
}
// QueuedIfd is one IFD that has been identified but yet to be processed.
type QueuedIfd struct {
Name string
IfdPath string
@ -1044,6 +1059,8 @@ type QueuedIfd struct {
ParentTagIndex int
}
// IfdIndex collects a bunch of IFD and tag information stored in several
// different ways in order to provide convenient lookups.
type IfdIndex struct {
RootIfd *Ifd
Ifds []*Ifd
@ -1051,7 +1068,8 @@ type IfdIndex struct {
Lookup map[string]*Ifd
}
// Scan enumerates the different EXIF blocks (called IFDs).
// Collect enumerates the different EXIF blocks (called IFDs) and builds out an
// index struct for referencing all of the parsed data.
func (ie *IfdEnumerate) Collect(rootIfdOffset uint32) (index IfdIndex, err error) {
defer func() {
if state := recover(); state != nil {
@ -1327,6 +1345,8 @@ func ParseOneTag(ifdMapping *IfdMapping, tagIndex *TagIndex, fqIfdPath, ifdPath
return tag, nil
}
// FindIfdFromRootIfd returns the given `Ifd` given the root-IFD and path of the
// desired IFD.
func FindIfdFromRootIfd(rootIfd *Ifd, ifdPath string) (ifd *Ifd, err error) {
defer func() {
if state := recover(); state != nil {