[feature] support processing of (many) more media types (#3090)

* initial work replacing our media decoding / encoding pipeline with ffprobe + ffmpeg

* specify the video codec to use when generating static image from emoji

* update go-storage library (fixes incompatibility after updating go-iotools)

* maintain image aspect ratio when generating a thumbnail for it

* update readme to show go-ffmpreg

* fix a bunch of media tests, move filesize checking to callers of media manager for more flexibility

* remove extra debug from error message

* fix up incorrect function signatures

* update PutFile to just use regular file copy, as changes are file is on separate partition

* fix remaining tests, remove some unneeded tests now we're working with ffmpeg/ffprobe

* update more tests, add more code comments

* add utilities to generate processed emoji / media outputs

* fix remaining tests

* add test for opus media file, add license header to utility cmds

* limit the number of concurrently available ffmpeg / ffprobe instances

* reduce number of instances

* further reduce number of instances

* fix envparsing test with configuration variables

* update docs and configuration with new media-{local,remote}-max-size variables

1 files changed, 0 insertions, 1199 deletions

diff --git a/vendor/github.com/dsoprea/go-exif/v3/ifd_builder.go b/vendor/github.com/dsoprea/go-exif/v3/ifd_builder.go
deleted file mode 100644
index a404b362a..000000000
--- a/vendor/github.com/dsoprea/go-exif/v3/ifd_builder.go
+++ /dev/null
@@ -1,1199 +0,0 @@
-package exif
-
-// NOTES:
-//
-// The thumbnail offset and length tags shouldn't be set directly. Use the
-// (*IfdBuilder).SetThumbnail() method instead.
-
-import (
-	"errors"
-	"fmt"
-	"strings"
-
-	"encoding/binary"
-
-	"github.com/dsoprea/go-logging"
-
-	"github.com/dsoprea/go-exif/v3/common"
-	"github.com/dsoprea/go-exif/v3/undefined"
-)
-
-var (
-	ifdBuilderLogger = log.NewLogger("exif.ifd_builder")
-)
-
-var (
-	ErrTagEntryNotFound = errors.New("tag entry not found")
-	ErrChildIbNotFound  = errors.New("child IB not found")
-)
-
-type IfdBuilderTagValue struct {
-	valueBytes []byte
-	ib         *IfdBuilder
-}
-
-func (ibtv IfdBuilderTagValue) String() string {
-	if ibtv.IsBytes() == true {
-		var valuePhrase string
-		if len(ibtv.valueBytes) <= 8 {
-			valuePhrase = fmt.Sprintf("%v", ibtv.valueBytes)
-		} else {
-			valuePhrase = fmt.Sprintf("%v...", ibtv.valueBytes[:8])
-		}
-
-		return fmt.Sprintf("IfdBuilderTagValue<BYTES=%v LEN=(%d)>", valuePhrase, len(ibtv.valueBytes))
-	} else if ibtv.IsIb() == true {
-		return fmt.Sprintf("IfdBuilderTagValue<IB=%s>", ibtv.ib)
-	} else {
-		log.Panicf("IBTV state undefined")
-		return ""
-	}
-}
-
-func NewIfdBuilderTagValueFromBytes(valueBytes []byte) *IfdBuilderTagValue {
-	return &IfdBuilderTagValue{
-		valueBytes: valueBytes,
-	}
-}
-
-func NewIfdBuilderTagValueFromIfdBuilder(ib *IfdBuilder) *IfdBuilderTagValue {
-	return &IfdBuilderTagValue{
-		ib: ib,
-	}
-}
-
-// IsBytes returns true if the bytes are populated. This is always the case
-// when we're loaded from a tag in an existing IFD.
-func (ibtv IfdBuilderTagValue) IsBytes() bool {
-	return ibtv.valueBytes != nil
-}
-
-func (ibtv IfdBuilderTagValue) Bytes() []byte {
-	if ibtv.IsBytes() == false {
-		log.Panicf("this tag is not a byte-slice value")
-	} else if ibtv.IsIb() == true {
-		log.Panicf("this tag is an IFD-builder value not a byte-slice")
-	}
-
-	return ibtv.valueBytes
-}
-
-func (ibtv IfdBuilderTagValue) IsIb() bool {
-	return ibtv.ib != nil
-}
-
-func (ibtv IfdBuilderTagValue) Ib() *IfdBuilder {
-	if ibtv.IsIb() == false {
-		log.Panicf("this tag is not an IFD-builder value")
-	} else if ibtv.IsBytes() == true {
-		log.Panicf("this tag is a byte-slice, not a IFD-builder")
-	}
-
-	return ibtv.ib
-}
-
-type BuilderTag struct {
-	// ifdPath is the path of the IFD that hosts this tag.
-	ifdPath string
-
-	tagId  uint16
-	typeId exifcommon.TagTypePrimitive
-
-	// value is either a value that can be encoded, an IfdBuilder instance (for
-	// child IFDs), or an IfdTagEntry instance representing an existing,
-	// previously-stored tag.
-	value *IfdBuilderTagValue
-
-	// byteOrder is the byte order. It's chiefly/originally here to support
-	// printing the value.
-	byteOrder binary.ByteOrder
-}
-
-func NewBuilderTag(ifdPath string, tagId uint16, typeId exifcommon.TagTypePrimitive, value *IfdBuilderTagValue, byteOrder binary.ByteOrder) *BuilderTag {
-	return &BuilderTag{
-		ifdPath:   ifdPath,
-		tagId:     tagId,
-		typeId:    typeId,
-		value:     value,
-		byteOrder: byteOrder,
-	}
-}
-
-func NewChildIfdBuilderTag(ifdPath string, tagId uint16, value *IfdBuilderTagValue) *BuilderTag {
-	return &BuilderTag{
-		ifdPath: ifdPath,
-		tagId:   tagId,
-		typeId:  exifcommon.TypeLong,
-		value:   value,
-	}
-}
-
-func (bt *BuilderTag) Value() (value *IfdBuilderTagValue) {
-	return bt.value
-}
-
-func (bt *BuilderTag) String() string {
-	var valueString string
-
-	if bt.value.IsBytes() == true {
-		var err error
-
-		valueString, err = exifcommon.FormatFromBytes(bt.value.Bytes(), bt.typeId, false, bt.byteOrder)
-		log.PanicIf(err)
-	} else {
-		valueString = fmt.Sprintf("%v", bt.value)
-	}
-
-	return fmt.Sprintf("BuilderTag<IFD-PATH=[%s] TAG-ID=(0x%04x) TAG-TYPE=[%s] VALUE=[%s]>", bt.ifdPath, bt.tagId, bt.typeId.String(), valueString)
-}
-
-func (bt *BuilderTag) SetValue(byteOrder binary.ByteOrder, value interface{}) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	// TODO(dustin): !! Add test.
-
-	var ed exifcommon.EncodedData
-	if bt.typeId == exifcommon.TypeUndefined {
-		encodeable := value.(exifundefined.EncodeableValue)
-
-		encoded, unitCount, err := exifundefined.Encode(encodeable, byteOrder)
-		log.PanicIf(err)
-
-		ed = exifcommon.EncodedData{
-			Type:      exifcommon.TypeUndefined,
-			Encoded:   encoded,
-			UnitCount: unitCount,
-		}
-	} else {
-		ve := exifcommon.NewValueEncoder(byteOrder)
-
-		var err error
-
-		ed, err = ve.Encode(value)
-		log.PanicIf(err)
-	}
-
-	bt.value = NewIfdBuilderTagValueFromBytes(ed.Encoded)
-
-	return nil
-}
-
-// NewStandardBuilderTag constructs a `BuilderTag` instance. The type is looked
-// up. `ii` is the type of IFD that owns this tag.
-func NewStandardBuilderTag(ifdPath string, it *IndexedTag, byteOrder binary.ByteOrder, value interface{}) *BuilderTag {
-	// If there is more than one supported type, we'll go with the larger to
-	// encode with. It'll use the same amount of fixed-space, and we'll
-	// eliminate unnecessary overflows/issues.
-	tagType := it.GetEncodingType(value)
-
-	var rawBytes []byte
-	if it.DoesSupportType(exifcommon.TypeUndefined) == true {
-		encodeable := value.(exifundefined.EncodeableValue)
-
-		var err error
-
-		rawBytes, _, err = exifundefined.Encode(encodeable, byteOrder)
-		log.PanicIf(err)
-	} else {
-		ve := exifcommon.NewValueEncoder(byteOrder)
-
-		ed, err := ve.Encode(value)
-		log.PanicIf(err)
-
-		rawBytes = ed.Encoded
-	}
-
-	tagValue := NewIfdBuilderTagValueFromBytes(rawBytes)
-
-	return NewBuilderTag(
-		ifdPath,
-		it.Id,
-		tagType,
-		tagValue,
-		byteOrder)
-}
-
-type IfdBuilder struct {
-	ifdIdentity *exifcommon.IfdIdentity
-
-	byteOrder binary.ByteOrder
-
-	// Includes both normal tags and IFD tags (which point to child IFDs).
-	// TODO(dustin): Keep a separate list of children like with `Ifd`.
-	// TODO(dustin): Either rename this or `Entries` in `Ifd` to be the same thing.
-	tags []*BuilderTag
-
-	// existingOffset will be the offset that this IFD is currently found at if
-	// it represents an IFD that has previously been stored (or 0 if not).
-	existingOffset uint32
-
-	// nextIb represents the next link if we're chaining to another.
-	nextIb *IfdBuilder
-
-	// thumbnailData is populated with thumbnail data if there was thumbnail
-	// data. Otherwise, it's nil.
-	thumbnailData []byte
-
-	ifdMapping *exifcommon.IfdMapping
-	tagIndex   *TagIndex
-}
-
-func NewIfdBuilder(ifdMapping *exifcommon.IfdMapping, tagIndex *TagIndex, ii *exifcommon.IfdIdentity, byteOrder binary.ByteOrder) (ib *IfdBuilder) {
-	ib = &IfdBuilder{
-		ifdIdentity: ii,
-
-		byteOrder: byteOrder,
-		tags:      make([]*BuilderTag, 0),
-
-		ifdMapping: ifdMapping,
-		tagIndex:   tagIndex,
-	}
-
-	return ib
-}
-
-// NewIfdBuilderWithExistingIfd creates a new IB using the same header type
-// information as the given IFD.
-func NewIfdBuilderWithExistingIfd(ifd *Ifd) (ib *IfdBuilder) {
-	ib = &IfdBuilder{
-		ifdIdentity: ifd.IfdIdentity(),
-
-		byteOrder:      ifd.ByteOrder(),
-		existingOffset: ifd.Offset(),
-		ifdMapping:     ifd.ifdMapping,
-		tagIndex:       ifd.tagIndex,
-	}
-
-	return ib
-}
-
-// NewIfdBuilderFromExistingChain creates a chain of IB instances from an
-// IFD chain generated from real data.
-func NewIfdBuilderFromExistingChain(rootIfd *Ifd) (firstIb *IfdBuilder) {
-	var lastIb *IfdBuilder
-	i := 0
-	for thisExistingIfd := rootIfd; thisExistingIfd != nil; thisExistingIfd = thisExistingIfd.nextIfd {
-		newIb := NewIfdBuilder(
-			rootIfd.ifdMapping,
-			rootIfd.tagIndex,
-			rootIfd.ifdIdentity,
-			thisExistingIfd.ByteOrder())
-
-		if firstIb == nil {
-			firstIb = newIb
-		} else {
-			lastIb.SetNextIb(newIb)
-		}
-
-		err := newIb.AddTagsFromExisting(thisExistingIfd, nil, nil)
-		log.PanicIf(err)
-
-		lastIb = newIb
-		i++
-	}
-
-	return firstIb
-}
-
-func (ib *IfdBuilder) IfdIdentity() *exifcommon.IfdIdentity {
-	return ib.ifdIdentity
-}
-
-func (ib *IfdBuilder) NextIb() (nextIb *IfdBuilder, err error) {
-	return ib.nextIb, nil
-}
-
-func (ib *IfdBuilder) ChildWithTagId(childIfdTagId uint16) (childIb *IfdBuilder, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	for _, bt := range ib.tags {
-		if bt.value.IsIb() == false {
-			continue
-		}
-
-		childIbThis := bt.value.Ib()
-
-		if childIbThis.IfdIdentity().TagId() == childIfdTagId {
-			return childIbThis, nil
-		}
-	}
-
-	log.Panic(ErrChildIbNotFound)
-
-	// Never reached.
-	return nil, nil
-}
-
-func getOrCreateIbFromRootIbInner(rootIb *IfdBuilder, parentIb *IfdBuilder, currentLineage []exifcommon.IfdTagIdAndIndex) (ib *IfdBuilder, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	// TODO(dustin): !! Add test.
-
-	thisIb := rootIb
-
-	// Since we're calling ourselves recursively with incrementally different
-	// paths, the FQ IFD-path of the parent that called us needs to be passed
-	// in, in order for us to know it.
-	var parentLineage []exifcommon.IfdTagIdAndIndex
-	if parentIb != nil {
-		var err error
-
-		parentLineage, err = thisIb.ifdMapping.ResolvePath(parentIb.IfdIdentity().String())
-		log.PanicIf(err)
-	}
-
-	// Process the current path part.
-	currentItIi := currentLineage[0]
-
-	// Make sure the leftmost part of the FQ IFD-path agrees with the IB we
-	// were given.
-
-	expectedFqRootIfdPath := ""
-	if parentLineage != nil {
-		expectedLineage := append(parentLineage, currentItIi)
-		expectedFqRootIfdPath = thisIb.ifdMapping.PathPhraseFromLineage(expectedLineage)
-	} else {
-		expectedFqRootIfdPath = thisIb.ifdMapping.PathPhraseFromLineage(currentLineage[:1])
-	}
-
-	if expectedFqRootIfdPath != thisIb.IfdIdentity().String() {
-		log.Panicf("the FQ IFD-path [%s] we were given does not match the builder's FQ IFD-path [%s]", expectedFqRootIfdPath, thisIb.IfdIdentity().String())
-	}
-
-	// If we actually wanted a sibling (currentItIi.Index > 0) then seek to it,
-	// appending new siblings, as required, until we get there.
-	for i := 0; i < currentItIi.Index; i++ {
-		if thisIb.nextIb == nil {
-			// Generate an FQ IFD-path for the sibling. It'll use the same
-			// non-FQ IFD-path as the current IB.
-
-			iiSibling := thisIb.IfdIdentity().NewSibling(i + 1)
-			thisIb.nextIb = NewIfdBuilder(thisIb.ifdMapping, thisIb.tagIndex, iiSibling, thisIb.byteOrder)
-		}
-
-		thisIb = thisIb.nextIb
-	}
-
-	// There is no child IFD to process. We're done.
-	if len(currentLineage) == 1 {
-		return thisIb, nil
-	}
-
-	// Establish the next child to be processed.
-
-	childItii := currentLineage[1]
-
-	var foundChild *IfdBuilder
-	for _, bt := range thisIb.tags {
-		if bt.value.IsIb() == false {
-			continue
-		}
-
-		childIb := bt.value.Ib()
-
-		if childIb.IfdIdentity().TagId() == childItii.TagId {
-			foundChild = childIb
-			break
-		}
-	}
-
-	// If we didn't find the child, add it.
-
-	if foundChild == nil {
-		currentIfdTag := thisIb.IfdIdentity().IfdTag()
-
-		childIfdTag :=
-			exifcommon.NewIfdTag(
-				&currentIfdTag,
-				childItii.TagId,
-				childItii.Name)
-
-		iiChild := thisIb.IfdIdentity().NewChild(childIfdTag, 0)
-
-		foundChild =
-			NewIfdBuilder(
-				thisIb.ifdMapping,
-				thisIb.tagIndex,
-				iiChild,
-				thisIb.byteOrder)
-
-		err = thisIb.AddChildIb(foundChild)
-		log.PanicIf(err)
-	}
-
-	finalIb, err := getOrCreateIbFromRootIbInner(foundChild, thisIb, currentLineage[1:])
-	log.PanicIf(err)
-
-	return finalIb, nil
-}
-
-// GetOrCreateIbFromRootIb returns an IB representing the requested IFD, even if
-// an IB doesn't already exist for it. This function may call itself
-// recursively.
-func GetOrCreateIbFromRootIb(rootIb *IfdBuilder, fqIfdPath string) (ib *IfdBuilder, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	// lineage is a necessity of our recursion process. It doesn't include any
-	// parent IFDs on its left-side; it starts with the current IB only.
-	lineage, err := rootIb.ifdMapping.ResolvePath(fqIfdPath)
-	log.PanicIf(err)
-
-	ib, err = getOrCreateIbFromRootIbInner(rootIb, nil, lineage)
-	log.PanicIf(err)
-
-	return ib, nil
-}
-
-func (ib *IfdBuilder) String() string {
-	nextIfdPhrase := ""
-	if ib.nextIb != nil {
-		// TODO(dustin): We were setting this to ii.String(), but we were getting hex-data when printing this after building from an existing chain.
-		nextIfdPhrase = ib.nextIb.IfdIdentity().UnindexedString()
-	}
-
-	return fmt.Sprintf("IfdBuilder<PATH=[%s] TAG-ID=(0x%04x) COUNT=(%d) OFF=(0x%04x) NEXT-IFD-PATH=[%s]>", ib.IfdIdentity().UnindexedString(), ib.IfdIdentity().TagId(), len(ib.tags), ib.existingOffset, nextIfdPhrase)
-}
-
-func (ib *IfdBuilder) Tags() (tags []*BuilderTag) {
-	return ib.tags
-}
-
-// SetThumbnail sets thumbnail data.
-//
-// NOTES:
-//
-// - We don't manage any facet of the thumbnail data. This is the
-//   responsibility of the user/developer.
-// - This method will fail unless the thumbnail is set on a the root IFD.
-//   However, in order to be valid, it must be set on the second one, linked to
-//   by the first, as per the EXIF/TIFF specification.
-// - We set the offset to (0) now but will allocate the data and properly assign
-//   the offset when the IB is encoded (later).
-func (ib *IfdBuilder) SetThumbnail(data []byte) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	if ib.IfdIdentity().UnindexedString() != exifcommon.IfdStandardIfdIdentity.UnindexedString() {
-		log.Panicf("thumbnails can only go into a root Ifd (and only the second one)")
-	}
-
-	// TODO(dustin): !! Add a test for this function.
-
-	if data == nil || len(data) == 0 {
-		log.Panic("thumbnail is empty")
-	}
-
-	ib.thumbnailData = data
-
-	ibtvfb := NewIfdBuilderTagValueFromBytes(ib.thumbnailData)
-	offsetBt :=
-		NewBuilderTag(
-			ib.IfdIdentity().UnindexedString(),
-			ThumbnailOffsetTagId,
-			exifcommon.TypeLong,
-			ibtvfb,
-			ib.byteOrder)
-
-	err = ib.Set(offsetBt)
-	log.PanicIf(err)
-
-	thumbnailSizeIt, err := ib.tagIndex.Get(ib.IfdIdentity(), ThumbnailSizeTagId)
-	log.PanicIf(err)
-
-	sizeBt := NewStandardBuilderTag(ib.IfdIdentity().UnindexedString(), thumbnailSizeIt, ib.byteOrder, []uint32{uint32(len(ib.thumbnailData))})
-
-	err = ib.Set(sizeBt)
-	log.PanicIf(err)
-
-	return nil
-}
-
-func (ib *IfdBuilder) Thumbnail() []byte {
-	return ib.thumbnailData
-}
-
-func (ib *IfdBuilder) printTagTree(levels int) {
-	indent := strings.Repeat(" ", levels*2)
-
-	i := 0
-	for currentIb := ib; currentIb != nil; currentIb = currentIb.nextIb {
-		prefix := " "
-		if i > 0 {
-			prefix = ">"
-		}
-
-		if levels == 0 {
-			fmt.Printf("%s%sIFD: %s INDEX=(%d)\n", indent, prefix, currentIb, i)
-		} else {
-			fmt.Printf("%s%sChild IFD: %s\n", indent, prefix, currentIb)
-		}
-
-		if len(currentIb.tags) > 0 {
-			fmt.Printf("\n")
-
-			for i, tag := range currentIb.tags {
-				isChildIb := false
-				_, err := ib.ifdMapping.GetChild(currentIb.IfdIdentity().UnindexedString(), tag.tagId)
-				if err == nil {
-					isChildIb = true
-				} else if log.Is(err, exifcommon.ErrChildIfdNotMapped) == false {
-					log.Panic(err)
-				}
-
-				tagName := ""
-
-				// If a normal tag (not a child IFD) get the name.
-				if isChildIb == true {
-					tagName = "<Child IFD>"
-				} else {
-					it, err := ib.tagIndex.Get(ib.ifdIdentity, tag.tagId)
-					if log.Is(err, ErrTagNotFound) == true {
-						tagName = "<UNKNOWN>"
-					} else if err != nil {
-						log.Panic(err)
-					} else {
-						tagName = it.Name
-					}
-				}
-
-				value := tag.Value()
-
-				if value.IsIb() == true {
-					fmt.Printf("%s  (%d): [%s] %s\n", indent, i, tagName, value.Ib())
-				} else {
-					fmt.Printf("%s  (%d): [%s] %s\n", indent, i, tagName, tag)
-				}
-
-				if isChildIb == true {
-					if tag.value.IsIb() == false {
-						log.Panicf("tag-ID (0x%04x) is an IFD but the tag value is not an IB instance: %v", tag.tagId, tag)
-					}
-
-					fmt.Printf("\n")
-
-					childIb := tag.value.Ib()
-					childIb.printTagTree(levels + 1)
-				}
-			}
-
-			fmt.Printf("\n")
-		}
-
-		i++
-	}
-}
-
-func (ib *IfdBuilder) PrintTagTree() {
-	ib.printTagTree(0)
-}
-
-func (ib *IfdBuilder) printIfdTree(levels int) {
-	indent := strings.Repeat(" ", levels*2)
-
-	i := 0
-	for currentIb := ib; currentIb != nil; currentIb = currentIb.nextIb {
-		prefix := " "
-		if i > 0 {
-			prefix = ">"
-		}
-
-		fmt.Printf("%s%s%s\n", indent, prefix, currentIb)
-
-		if len(currentIb.tags) > 0 {
-			for _, tag := range currentIb.tags {
-				isChildIb := false
-				_, err := ib.ifdMapping.GetChild(currentIb.IfdIdentity().UnindexedString(), tag.tagId)
-				if err == nil {
-					isChildIb = true
-				} else if log.Is(err, exifcommon.ErrChildIfdNotMapped) == false {
-					log.Panic(err)
-				}
-
-				if isChildIb == true {
-					if tag.value.IsIb() == false {
-						log.Panicf("tag-ID (0x%04x) is an IFD but the tag value is not an IB instance: %v", tag.tagId, tag)
-					}
-
-					childIb := tag.value.Ib()
-					childIb.printIfdTree(levels + 1)
-				}
-			}
-		}
-
-		i++
-	}
-}
-
-func (ib *IfdBuilder) PrintIfdTree() {
-	ib.printIfdTree(0)
-}
-
-func (ib *IfdBuilder) dumpToStrings(thisIb *IfdBuilder, prefix string, tagId uint16, lines []string) (linesOutput []string) {
-	if lines == nil {
-		linesOutput = make([]string, 0)
-	} else {
-		linesOutput = lines
-	}
-
-	siblingIfdIndex := 0
-	for ; thisIb != nil; thisIb = thisIb.nextIb {
-		line := fmt.Sprintf("IFD<PARENTS=[%s] FQ-IFD-PATH=[%s] IFD-INDEX=(%d) IFD-TAG-ID=(0x%04x) TAG=[0x%04x]>", prefix, thisIb.IfdIdentity().String(), siblingIfdIndex, thisIb.IfdIdentity().TagId(), tagId)
-		linesOutput = append(linesOutput, line)
-
-		for i, tag := range thisIb.tags {
-			var childIb *IfdBuilder
-			childIfdName := ""
-			if tag.value.IsIb() == true {
-				childIb = tag.value.Ib()
-				childIfdName = childIb.IfdIdentity().UnindexedString()
-			}
-
-			line := fmt.Sprintf("TAG<PARENTS=[%s] FQ-IFD-PATH=[%s] IFD-TAG-ID=(0x%04x) CHILD-IFD=[%s] TAG-INDEX=(%d) TAG=[0x%04x]>", prefix, thisIb.IfdIdentity().String(), thisIb.IfdIdentity().TagId(), childIfdName, i, tag.tagId)
-			linesOutput = append(linesOutput, line)
-
-			if childIb == nil {
-				continue
-			}
-
-			childPrefix := ""
-			if prefix == "" {
-				childPrefix = fmt.Sprintf("%s", thisIb.IfdIdentity().UnindexedString())
-			} else {
-				childPrefix = fmt.Sprintf("%s->%s", prefix, thisIb.IfdIdentity().UnindexedString())
-			}
-
-			linesOutput = thisIb.dumpToStrings(childIb, childPrefix, tag.tagId, linesOutput)
-		}
-
-		siblingIfdIndex++
-	}
-
-	return linesOutput
-}
-
-func (ib *IfdBuilder) DumpToStrings() (lines []string) {
-	return ib.dumpToStrings(ib, "", 0, lines)
-}
-
-func (ib *IfdBuilder) SetNextIb(nextIb *IfdBuilder) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	ib.nextIb = nextIb
-
-	return nil
-}
-
-func (ib *IfdBuilder) DeleteN(tagId uint16, n int) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	if n < 1 {
-		log.Panicf("N must be at least 1: (%d)", n)
-	}
-
-	for n > 0 {
-		j := -1
-		for i, bt := range ib.tags {
-			if bt.tagId == tagId {
-				j = i
-				break
-			}
-		}
-
-		if j == -1 {
-			log.Panic(ErrTagEntryNotFound)
-		}
-
-		ib.tags = append(ib.tags[:j], ib.tags[j+1:]...)
-		n--
-	}
-
-	return nil
-}
-
-func (ib *IfdBuilder) DeleteFirst(tagId uint16) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	err = ib.DeleteN(tagId, 1)
-	log.PanicIf(err)
-
-	return nil
-}
-
-func (ib *IfdBuilder) DeleteAll(tagId uint16) (n int, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	for {
-		err = ib.DeleteN(tagId, 1)
-		if log.Is(err, ErrTagEntryNotFound) == true {
-			break
-		} else if err != nil {
-			log.Panic(err)
-		}
-
-		n++
-	}
-
-	return n, nil
-}
-
-func (ib *IfdBuilder) ReplaceAt(position int, bt *BuilderTag) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	if position < 0 {
-		log.Panicf("replacement position must be 0 or greater")
-	} else if position >= len(ib.tags) {
-		log.Panicf("replacement position does not exist")
-	}
-
-	ib.tags[position] = bt
-
-	return nil
-}
-
-func (ib *IfdBuilder) Replace(tagId uint16, bt *BuilderTag) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	position, err := ib.Find(tagId)
-	log.PanicIf(err)
-
-	ib.tags[position] = bt
-
-	return nil
-}
-
-// Set will add a new entry or update an existing entry.
-func (ib *IfdBuilder) Set(bt *BuilderTag) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	position, err := ib.Find(bt.tagId)
-	if err == nil {
-		ib.tags[position] = bt
-	} else if log.Is(err, ErrTagEntryNotFound) == true {
-		err = ib.add(bt)
-		log.PanicIf(err)
-	} else {
-		log.Panic(err)
-	}
-
-	return nil
-}
-
-func (ib *IfdBuilder) FindN(tagId uint16, maxFound int) (found []int, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	found = make([]int, 0)
-
-	for i, bt := range ib.tags {
-		if bt.tagId == tagId {
-			found = append(found, i)
-			if maxFound == 0 || len(found) >= maxFound {
-				break
-			}
-		}
-	}
-
-	return found, nil
-}
-
-func (ib *IfdBuilder) Find(tagId uint16) (position int, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	found, err := ib.FindN(tagId, 1)
-	log.PanicIf(err)
-
-	if len(found) == 0 {
-		log.Panic(ErrTagEntryNotFound)
-	}
-
-	return found[0], nil
-}
-
-func (ib *IfdBuilder) FindTag(tagId uint16) (bt *BuilderTag, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	found, err := ib.FindN(tagId, 1)
-	log.PanicIf(err)
-
-	if len(found) == 0 {
-		log.Panic(ErrTagEntryNotFound)
-	}
-
-	position := found[0]
-
-	return ib.tags[position], nil
-}
-
-func (ib *IfdBuilder) FindTagWithName(tagName string) (bt *BuilderTag, err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	it, err := ib.tagIndex.GetWithName(ib.IfdIdentity(), tagName)
-	log.PanicIf(err)
-
-	found, err := ib.FindN(it.Id, 1)
-	log.PanicIf(err)
-
-	if len(found) == 0 {
-		log.Panic(ErrTagEntryNotFound)
-	}
-
-	position := found[0]
-
-	return ib.tags[position], nil
-}
-
-func (ib *IfdBuilder) add(bt *BuilderTag) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	if bt.ifdPath == "" {
-		log.Panicf("BuilderTag ifdPath is not set: %s", bt)
-	} else if bt.typeId == 0x0 {
-		log.Panicf("BuilderTag type-ID is not set: %s", bt)
-	} else if bt.value == nil {
-		log.Panicf("BuilderTag value is not set: %s", bt)
-	}
-
-	ib.tags = append(ib.tags, bt)
-	return nil
-}
-
-func (ib *IfdBuilder) Add(bt *BuilderTag) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	if bt.value.IsIb() == true {
-		log.Panicf("child IfdBuilders must be added via AddChildIb() or AddTagsFromExisting(), not Add()")
-	}
-
-	err = ib.add(bt)
-	log.PanicIf(err)
-
-	return nil
-}
-
-// AddChildIb adds a tag that branches to a new IFD.
-func (ib *IfdBuilder) AddChildIb(childIb *IfdBuilder) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	if childIb.IfdIdentity().TagId() == 0 {
-		log.Panicf("IFD can not be used as a child IFD (not associated with a tag-ID): %v", childIb)
-	} else if childIb.byteOrder != ib.byteOrder {
-		log.Panicf("Child IFD does not have the same byte-order: [%s] != [%s]", childIb.byteOrder, ib.byteOrder)
-	}
-
-	// Since no standard IFDs supports occur`ring more than once, check that a
-	// tag of this type has not been previously added. Note that we just search
-	// the current IFD and *not every* IFD.
-	for _, bt := range childIb.tags {
-		if bt.tagId == childIb.IfdIdentity().TagId() {
-			log.Panicf("child-IFD already added: %v", childIb.IfdIdentity().UnindexedString())
-		}
-	}
-
-	bt := ib.NewBuilderTagFromBuilder(childIb)
-	ib.tags = append(ib.tags, bt)
-
-	return nil
-}
-
-func (ib *IfdBuilder) NewBuilderTagFromBuilder(childIb *IfdBuilder) (bt *BuilderTag) {
-	defer func() {
-		if state := recover(); state != nil {
-			err := log.Wrap(state.(error))
-			log.Panic(err)
-		}
-	}()
-
-	value := NewIfdBuilderTagValueFromIfdBuilder(childIb)
-
-	bt = NewChildIfdBuilderTag(
-		ib.IfdIdentity().UnindexedString(),
-		childIb.IfdIdentity().TagId(),
-		value)
-
-	return bt
-}
-
-// AddTagsFromExisting does a verbatim copy of the entries in `ifd` to this
-// builder. It excludes child IFDs. These must be added explicitly via
-// `AddChildIb()`.
-func (ib *IfdBuilder) AddTagsFromExisting(ifd *Ifd, includeTagIds []uint16, excludeTagIds []uint16) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	thumbnailData, err := ifd.Thumbnail()
-	if err == nil {
-		err = ib.SetThumbnail(thumbnailData)
-		log.PanicIf(err)
-	} else if log.Is(err, ErrNoThumbnail) == false {
-		log.Panic(err)
-	}
-
-	for i, ite := range ifd.Entries() {
-		if ite.IsThumbnailOffset() == true || ite.IsThumbnailSize() {
-			// These will be added on-the-fly when we encode.
-			continue
-		}
-
-		if excludeTagIds != nil && len(excludeTagIds) > 0 {
-			found := false
-			for _, excludedTagId := range excludeTagIds {
-				if excludedTagId == ite.TagId() {
-					found = true
-				}
-			}
-
-			if found == true {
-				continue
-			}
-		}
-
-		if includeTagIds != nil && len(includeTagIds) > 0 {
-			// Whether or not there was a list of excludes, if there is a list
-			// of includes than the current tag has to be in it.
-
-			found := false
-			for _, includedTagId := range includeTagIds {
-				if includedTagId == ite.TagId() {
-					found = true
-					break
-				}
-			}
-
-			if found == false {
-				continue
-			}
-		}
-
-		var bt *BuilderTag
-
-		if ite.ChildIfdPath() != "" {
-			// If we want to add an IFD tag, we'll have to build it first and
-			// *then* add it via a different method.
-
-			// Figure out which of the child-IFDs that are associated with
-			// this IFD represents this specific child IFD.
-
-			var childIfd *Ifd
-			for _, thisChildIfd := range ifd.Children() {
-				if thisChildIfd.ParentTagIndex() != i {
-					continue
-				} else if thisChildIfd.ifdIdentity.TagId() != 0xffff && thisChildIfd.ifdIdentity.TagId() != ite.TagId() {
-					log.Panicf("child-IFD tag is not correct: TAG-POSITION=(%d) ITE=%s CHILD-IFD=%s", thisChildIfd.ParentTagIndex(), ite, thisChildIfd)
-				}
-
-				childIfd = thisChildIfd
-				break
-			}
-
-			if childIfd == nil {
-				childTagIds := make([]string, len(ifd.Children()))
-				for j, childIfd := range ifd.Children() {
-					childTagIds[j] = fmt.Sprintf("0x%04x (parent tag-position %d)", childIfd.ifdIdentity.TagId(), childIfd.ParentTagIndex())
-				}
-
-				log.Panicf("could not find child IFD for child ITE: IFD-PATH=[%s] TAG-ID=(0x%04x) CURRENT-TAG-POSITION=(%d) CHILDREN=%v", ite.IfdPath(), ite.TagId(), i, childTagIds)
-			}
-
-			childIb := NewIfdBuilderFromExistingChain(childIfd)
-			bt = ib.NewBuilderTagFromBuilder(childIb)
-		} else {
-			// Non-IFD tag.
-
-			rawBytes, err := ite.GetRawBytes()
-			log.PanicIf(err)
-
-			value := NewIfdBuilderTagValueFromBytes(rawBytes)
-
-			bt = NewBuilderTag(
-				ifd.ifdIdentity.UnindexedString(),
-				ite.TagId(),
-				ite.TagType(),
-				value,
-				ib.byteOrder)
-		}
-
-		err := ib.add(bt)
-		log.PanicIf(err)
-	}
-
-	return nil
-}
-
-// AddStandard quickly and easily composes and adds the tag using the
-// information already known about a tag. Only works with standard tags.
-func (ib *IfdBuilder) AddStandard(tagId uint16, value interface{}) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	it, err := ib.tagIndex.Get(ib.IfdIdentity(), tagId)
-	log.PanicIf(err)
-
-	bt := NewStandardBuilderTag(ib.IfdIdentity().UnindexedString(), it, ib.byteOrder, value)
-
-	err = ib.add(bt)
-	log.PanicIf(err)
-
-	return nil
-}
-
-// AddStandardWithName quickly and easily composes and adds the tag using the
-// information already known about a tag (using the name). Only works with
-// standard tags.
-func (ib *IfdBuilder) AddStandardWithName(tagName string, value interface{}) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	it, err := ib.tagIndex.GetWithName(ib.IfdIdentity(), tagName)
-	log.PanicIf(err)
-
-	bt := NewStandardBuilderTag(ib.IfdIdentity().UnindexedString(), it, ib.byteOrder, value)
-
-	err = ib.add(bt)
-	log.PanicIf(err)
-
-	return nil
-}
-
-// SetStandard quickly and easily composes and adds or replaces the tag using
-// the information already known about a tag. Only works with standard tags.
-func (ib *IfdBuilder) SetStandard(tagId uint16, value interface{}) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	// TODO(dustin): !! Add test for this function.
-
-	it, err := ib.tagIndex.Get(ib.IfdIdentity(), tagId)
-	log.PanicIf(err)
-
-	bt := NewStandardBuilderTag(ib.IfdIdentity().UnindexedString(), it, ib.byteOrder, value)
-
-	i, err := ib.Find(tagId)
-	if err != nil {
-		if log.Is(err, ErrTagEntryNotFound) == false {
-			log.Panic(err)
-		}
-
-		ib.tags = append(ib.tags, bt)
-	} else {
-		ib.tags[i] = bt
-	}
-
-	return nil
-}
-
-// SetStandardWithName quickly and easily composes and adds or replaces the
-// tag using the information already known about a tag (using the name). Only
-// works with standard tags.
-func (ib *IfdBuilder) SetStandardWithName(tagName string, value interface{}) (err error) {
-	defer func() {
-		if state := recover(); state != nil {
-			err = log.Wrap(state.(error))
-		}
-	}()
-
-	// TODO(dustin): !! Add test for this function.
-
-	it, err := ib.tagIndex.GetWithName(ib.IfdIdentity(), tagName)
-	log.PanicIf(err)
-
-	bt := NewStandardBuilderTag(ib.IfdIdentity().UnindexedString(), it, ib.byteOrder, value)
-
-	i, err := ib.Find(bt.tagId)
-	if err != nil {
-		if log.Is(err, ErrTagEntryNotFound) == false {
-			log.Panic(err)
-		}
-
-		ib.tags = append(ib.tags, bt)
-	} else {
-		ib.tags[i] = bt
-	}
-
-	return nil
-}