ifd_enumerate: Added tests.

- Refactored (IfdTagEntry).ValueBytes() to handle managed undefined
  values.

exif.go

@@ -135,14 +135,14 @@ func (e *Exif) ParseExifHeader(data []byte) (eh ExifHeader, err error) {
     return eh, nil
 }
 
-func (e *Exif) Visit(exifData []byte, visitor TagVisitor) (err error) {
+func (e *Exif) Visit(exifData []byte, visitor TagVisitor) (eh ExifHeader, err error) {
     defer func() {
         if state := recover(); state != nil {
             err = log.Wrap(state.(error))
         }
     }()
 
-    eh, err := e.ParseExifHeader(exifData)
+    eh, err = e.ParseExifHeader(exifData)
     log.PanicIf(err)
 
     ie := NewIfdEnumerate(exifData, eh.ByteOrder)
@@ -150,17 +150,17 @@ func (e *Exif) Visit(exifData []byte, visitor TagVisitor) (err error) {
     err = ie.Scan(IfdStandard, eh.FirstIfdOffset, visitor)
     log.PanicIf(err)
 
-    return nil
+    return eh, nil
 }
 
-func (e *Exif) Collect(exifData []byte) (index IfdIndex, err error) {
+func (e *Exif) Collect(exifData []byte) (eh ExifHeader, index IfdIndex, err error) {
     defer func() {
         if state := recover(); state != nil {
             err = log.Wrap(state.(error))
         }
     }()
 
-    eh, err := e.ParseExifHeader(exifData)
+    eh, err = e.ParseExifHeader(exifData)
     log.PanicIf(err)
 
     ie := NewIfdEnumerate(exifData, eh.ByteOrder)
@@ -168,5 +168,5 @@ func (e *Exif) Collect(exifData []byte) (index IfdIndex, err error) {
     index, err = ie.Collect(eh.FirstIfdOffset)
     log.PanicIf(err)
 
-    return index, nil
+    return eh, index, nil
 }

exif_test.go

@@ -109,7 +109,7 @@ func TestVisit(t *testing.T) {
         return nil
     }
 
-    err = e.Visit(data[foundAt:], visitor)
+    _, err = e.Visit(data[foundAt:], visitor)
     log.PanicIf(err)
 
     // for _, line := range tags {
@@ -198,7 +198,7 @@ func TestCollect(t *testing.T) {
     rawExif, err := e.SearchAndExtractExif(filepath)
     log.PanicIf(err)
 
-    index, err := e.Collect(rawExif)
+    _, index, err := e.Collect(rawExif)
     log.PanicIf(err)
 
     rootIfd := index.RootIfd
@@ -257,7 +257,7 @@ func TestCollect(t *testing.T) {
     foundExif := 0
     foundGps := 0
     for _, ite := range lookup[IfdStandard][0].Entries {
-        if ite.IfdName == IfdExif {
+        if ite.ChildIfdName == IfdExif {
             foundExif++
 
             if IfdTagNames[ite.TagId] != IfdExif {
@@ -265,7 +265,7 @@ func TestCollect(t *testing.T) {
             }
         }
 
-        if ite.IfdName == IfdGps {
+        if ite.ChildIfdName == IfdGps {
             foundGps++
 
             if IfdTagNames[ite.TagId] != IfdGps {
@@ -282,7 +282,7 @@ func TestCollect(t *testing.T) {
 
     foundIop := 0
     for _, ite := range lookup[IfdExif][0].Entries {
-        if ite.IfdName == IfdIop {
+        if ite.ChildIfdName == IfdIop {
             foundIop++
 
             if IfdTagNames[ite.TagId] != IfdIop {

ifd_builder.go

@@ -29,11 +29,11 @@ type builderTag struct {
     // 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 interface{}
+    valueBytes interface{}
 }
 
 func (bt builderTag) String() string {
-    return fmt.Sprintf("BuilderTag<TAG-ID=(0x%02x) IFD=[%s] VALUE=[%v]>", bt.tagId, bt.ifdName, bt.value)
+    return fmt.Sprintf("BuilderTag<TAG-ID=(0x%02x) IFD=[%s] VALUE=[%v]>", bt.tagId, bt.ifdName, bt.valueBytes)
 }
 
 
@@ -463,7 +463,7 @@ func (ib *IfdBuilder) AddChildIfd(childIfd *IfdBuilder) (err error) {
     bt := builderTag{
         ifdName: childIfd.ifdName,
         tagId: childIfd.ifdTagId,
-        value: childIfd,
+        valueBytes: childIfd,
     }
 
     ib.Add(bt)
@@ -474,7 +474,7 @@ func (ib *IfdBuilder) AddChildIfd(childIfd *IfdBuilder) (err error) {
 // AddTagsFromExisting does a verbatim copy of the entries in `ifd` to this
 // builder. It excludes child IFDs. This must be added explicitly via
 // `AddChildIfd()`.
-func (ib *IfdBuilder) AddTagsFromExisting(ifd *Ifd, includeTagIds []uint16, excludeTagIds []uint16) (err error) {
+func (ib *IfdBuilder) AddTagsFromExisting(ifd *Ifd, itevr *IfdTagEntryValueResolver, includeTagIds []uint16, excludeTagIds []uint16) (err error) {
     defer func() {
         if state := recover(); state != nil {
             err = log.Wrap(state.(error))
@@ -498,22 +498,17 @@ func (ib *IfdBuilder) AddTagsFromExisting(ifd *Ifd, includeTagIds []uint16, excl
 //     an IfdEnumerator and then be read and re-read (like an IEnumerable vs IList).
 
 
-// TODO(dustin): !! Finish.
-    // itevr := NewIfdTagEntryValueResolver(rawExif []byte, ib.byteOrder)
-    // itevr.ValueBytes(ite *IfdTagEntry) (value []byte, err error)
-
-
-    for _, tag := range ifd.Entries {
+    for _, ite := range ifd.Entries {
         // If we want to add an IFD tag, we'll have to build it first and *then*
         // add it via a different method.
-        if tag.IfdName != "" {
+        if ite.ChildIfdName != "" {
             continue
         }
 
         if excludeTagIds != nil && len(excludeTagIds) > 0 {
             found := false
             for _, excludedTagId := range excludeTagIds {
-                if excludedTagId == tag.TagId {
+                if excludedTagId == ite.TagId {
                     found = true
                 }
             }
@@ -529,7 +524,7 @@ func (ib *IfdBuilder) AddTagsFromExisting(ifd *Ifd, includeTagIds []uint16, excl
 
             found := false
             for _, includedTagId := range includeTagIds {
-                if includedTagId == tag.TagId {
+                if includedTagId == ite.TagId {
                     found = true
                     break
                 }
@@ -541,10 +536,14 @@ func (ib *IfdBuilder) AddTagsFromExisting(ifd *Ifd, includeTagIds []uint16, excl
         }
 
         bt := builderTag{
-            tagId: tag.TagId,
+            tagId: ite.TagId,
+        }
 
-// TODO(dustin): !! For right now, a IfdTagEntry instance will mean that the value will have to be inherited/copied from an existing offset.
-            value: tag,
+        if itevr != nil {
+            var err error
+
+            bt.valueBytes, err = itevr.ValueBytes(&ite)
+            log.PanicIf(err)
         }
 
         err := ib.Add(bt)

ifd_builder_test.go

@@ -18,21 +18,21 @@ func TestAdd(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
@@ -41,7 +41,7 @@ func TestAdd(t *testing.T) {
 
     bt = builderTag{
         tagId: 0x44,
-        value: originalShorts,
+        valueBytes: originalShorts,
     }
 
     ib.Add(bt)
@@ -64,25 +64,25 @@ func TestAdd(t *testing.T) {
 
     if tags[0].tagId != 0x11 {
         t.Fatalf("tag (0) tag-ID not correct")
-    } else if tags[0].value != "test string" {
+    } else if tags[0].valueBytes != "test string" {
         t.Fatalf("tag (0) value not correct")
     }
 
     if tags[1].tagId != 0x22 {
         t.Fatalf("tag (1) tag-ID not correct")
-    } else if tags[1].value != "test string2" {
+    } else if tags[1].valueBytes != "test string2" {
         t.Fatalf("tag (1) value not correct")
     }
 
     if tags[2].tagId != 0x33 {
         t.Fatalf("tag (2) tag-ID not correct")
-    } else if tags[2].value != "test string3" {
+    } else if tags[2].valueBytes != "test string3" {
         t.Fatalf("tag (2) value not correct")
     }
 
     if tags[3].tagId != 0x44 {
         t.Fatalf("tag (3) tag-ID not correct")
-    } else if reflect.DeepEqual(tags[3].value.([]uint16), originalShorts) != true {
+    } else if reflect.DeepEqual(tags[3].valueBytes.([]uint16), originalShorts) != true {
         t.Fatalf("tag (3) value not correct")
     }
 }
@@ -111,7 +111,7 @@ func TestAddChildIfd(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
@@ -122,7 +122,7 @@ func TestAddChildIfd(t *testing.T) {
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
@@ -131,7 +131,7 @@ func TestAddChildIfd(t *testing.T) {
         t.Fatalf("first tag not correct")
     } else if ib.tags[1].tagId != ibChild.ifdTagId {
         t.Fatalf("second tag ID does not match child-IFD tag-ID")
-    } else if ib.tags[1].value != ibChild {
+    } else if ib.tags[1].valueBytes != ibChild {
         t.Fatalf("second tagvalue does not match child-IFD")
     } else if ib.tags[2].tagId != 0x22 {
         t.Fatalf("third tag not correct")
@@ -149,7 +149,7 @@ func TestAddTagsFromExisting(t *testing.T) {
 
     entries[1] = IfdTagEntry{
         TagId: 0x22,
-        IfdName: "some ifd",
+        ChildIfdName: "some ifd",
     }
 
     entries[2] = IfdTagEntry{
@@ -160,7 +160,7 @@ func TestAddTagsFromExisting(t *testing.T) {
         Entries: entries,
     }
 
-    err := ib.AddTagsFromExisting(ifd, nil, nil)
+    err := ib.AddTagsFromExisting(ifd, nil, nil, nil)
     log.PanicIf(err)
 
     if ib.tags[0].tagId != 0x11 {
@@ -183,7 +183,7 @@ func TestAddTagsFromExisting__Includes(t *testing.T) {
 
     entries[1] = IfdTagEntry{
         TagId: 0x22,
-        IfdName: "some ifd",
+        ChildIfdName: "some ifd",
     }
 
     entries[2] = IfdTagEntry{
@@ -194,7 +194,7 @@ func TestAddTagsFromExisting__Includes(t *testing.T) {
         Entries: entries,
     }
 
-    err := ib.AddTagsFromExisting(ifd, []uint16 { 0x33 }, nil)
+    err := ib.AddTagsFromExisting(ifd, nil, []uint16 { 0x33 }, nil)
     log.PanicIf(err)
 
     if ib.tags[0].tagId != 0x33 {
@@ -215,7 +215,7 @@ func TestAddTagsFromExisting__Excludes(t *testing.T) {
 
     entries[1] = IfdTagEntry{
         TagId: 0x22,
-        IfdName: "some ifd",
+        ChildIfdName: "some ifd",
     }
 
     entries[2] = IfdTagEntry{
@@ -226,7 +226,7 @@ func TestAddTagsFromExisting__Excludes(t *testing.T) {
         Entries: entries,
     }
 
-    err := ib.AddTagsFromExisting(ifd, nil, []uint16 { 0x11 })
+    err := ib.AddTagsFromExisting(ifd, nil, nil, []uint16 { 0x11 })
     log.PanicIf(err)
 
     if ib.tags[0].tagId != 0x33 {
@@ -241,21 +241,21 @@ func TestFindN_First_1(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
@@ -282,21 +282,21 @@ func TestFindN_First_2_1Returned(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
@@ -323,35 +323,35 @@ func TestFindN_First_2_2Returned(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string5",
+        valueBytes: "test string5",
     }
 
     ib.Add(bt)
@@ -370,13 +370,13 @@ func TestFindN_First_2_2Returned(t *testing.T) {
     tags := ib.Tags()
 
     bt = tags[found[0]]
-    if bt.tagId != 0x11 || bt.value != "test string" {
-        log.Panicf("Found entry 0 is not correct: (0x%02x) [%s]", bt.tagId, bt.value)
+    if bt.tagId != 0x11 || bt.valueBytes != "test string" {
+        log.Panicf("Found entry 0 is not correct: (0x%02x) [%s]", bt.tagId, bt.valueBytes)
     }
 
     bt = tags[found[1]]
-    if bt.tagId != 0x11 || bt.value != "test string4" {
-        log.Panicf("Found entry 1 is not correct: (0x%02x) [%s]", bt.tagId, bt.value)
+    if bt.tagId != 0x11 || bt.valueBytes != "test string4" {
+        log.Panicf("Found entry 1 is not correct: (0x%02x) [%s]", bt.tagId, bt.valueBytes)
     }
 }
 
@@ -385,42 +385,42 @@ func TestFindN_Middle_WithDuplicates(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string5",
+        valueBytes: "test string5",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string6",
+        valueBytes: "test string6",
     }
 
     ib.Add(bt)
@@ -447,28 +447,28 @@ func TestFindN_Middle_NoDuplicates(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
@@ -506,28 +506,28 @@ func TestFind_Hit(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
@@ -552,28 +552,28 @@ func TestFind_Miss(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x11,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
@@ -591,21 +591,21 @@ func TestReplace(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
@@ -621,7 +621,7 @@ func TestReplace(t *testing.T) {
 
     bt = builderTag{
         tagId: 0x99,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     err := ib.Replace(0x22, bt)
@@ -642,21 +642,21 @@ func TestReplaceN(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
@@ -672,7 +672,7 @@ func TestReplaceN(t *testing.T) {
 
     bt = builderTag{
         tagId: 0xA9,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     err := ib.ReplaceAt(1, bt)
@@ -693,28 +693,28 @@ func TestDeleteFirst(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
@@ -781,28 +781,28 @@ func TestDeleteN(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
@@ -869,28 +869,28 @@ func TestDeleteN_Two(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)
@@ -940,28 +940,28 @@ func TestDeleteAll(t *testing.T) {
 
     bt := builderTag{
         tagId: 0x11,
-        value: "test string",
+        valueBytes: "test string",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string2",
+        valueBytes: "test string2",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x22,
-        value: "test string3",
+        valueBytes: "test string3",
     }
 
     ib.Add(bt)
 
     bt = builderTag{
         tagId: 0x33,
-        value: "test string4",
+        valueBytes: "test string4",
     }
 
     ib.Add(bt)

ifd_enumerate.go

@@ -137,9 +137,18 @@ type IfdTagEntry struct {
     UnitCount uint32
     ValueOffset uint32
     RawValueOffset []byte
+
+    // ChildIfdName is a name if this tag represents a child IFD.
+    ChildIfdName string
+
+    // IfdName is the IFD that this tag belongs to.
     IfdName string
 }
 
+func (ite IfdTagEntry) String() string {
+    return fmt.Sprintf("IfdTagEntry<TAG-IFD=[%s] TAG-ID=(0x%02x) TAG-TYPE=[%s] UNIT-COUNT=(%d)>", ite.ChildIfdName, ite.TagId, TypeNames[ite.TagType], ite.UnitCount)
+}
+
 func (ite IfdTagEntry) ValueBytes(addressableData []byte, byteOrder binary.ByteOrder) (value []byte, err error) {
     defer func() {
         if state := recover(); state != nil {
@@ -147,6 +156,28 @@ func (ite IfdTagEntry) ValueBytes(addressableData []byte, byteOrder binary.ByteO
         }
     }()
 
+    if ite.TagType == TypeUndefined {
+        valueContext := ValueContext{
+            UnitCount: ite.UnitCount,
+            ValueOffset: ite.ValueOffset,
+            RawValueOffset: ite.RawValueOffset,
+            AddressableData: addressableData,
+        }
+
+        value, err := UndefinedValue(ite.IfdName, ite.TagId, valueContext, byteOrder)
+        log.PanicIf(err)
+
+        switch value.(type) {
+        case []byte:
+            return value.([]byte), nil
+        case string:
+            return []byte(value.(string)), 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%02x)", ite.TagId)
+        }
+    }
+
     originalType := NewTagType(ite.TagType, byteOrder)
     byteCount := uint32(originalType.Size()) * ite.UnitCount
 
@@ -260,6 +291,7 @@ func (ie *IfdEnumerate) ParseIfd(ifdName string, ifdIndex int, ifdOffset uint32,
         }
 
         tag := IfdTagEntry{
+            IfdName: ifdName,
             TagId: tagId,
             TagIndex: int(i),
             TagType: tagType,
@@ -270,7 +302,7 @@ func (ie *IfdEnumerate) ParseIfd(ifdName string, ifdIndex int, ifdOffset uint32,
 
         childIfdName, isIfd := IsIfdTag(tagId)
         if isIfd == true {
-            tag.IfdName = childIfdName
+            tag.ChildIfdName = childIfdName
 
             if doDescend == true {
                 ifdEnumerateLogger.Debugf(nil, "Descending to IFD [%s].", childIfdName)
@@ -320,7 +352,10 @@ type Ifd struct {
     Name string
     Index int
     Offset uint32
+
+// TODO(dustin): !! Add a find method.
     Entries []IfdTagEntry
+
     Children []*Ifd
     NextIfdOffset uint32
     NextIfd *Ifd
@@ -455,12 +490,12 @@ func (ie *IfdEnumerate) Collect(rootIfdOffset uint32) (index IfdIndex, err error
 
         // Determine if any of our entries is a child IFD and queue it.
         for _, entry := range entries {
-            if entry.IfdName == "" {
+            if entry.ChildIfdName == "" {
                 continue
             }
 
             qi := QueuedIfd {
-                Name: entry.IfdName,
+                Name: entry.ChildIfdName,
                 Index: 0,
                 Offset: entry.ValueOffset,
                 Parent: &ifd,

ifd_enumerate_test.go

@@ -0,0 +1,173 @@
+package exif
+
+import (
+    "path"
+    "testing"
+    "bytes"
+
+    "encoding/binary"
+
+    "github.com/dsoprea/go-logging"
+)
+
+func TestIfdTagEntry_ValueBytes(t *testing.T) {
+    byteOrder := binary.BigEndian
+    ve := NewValueEncoder(byteOrder)
+
+    original := []byte("original text")
+
+    ed, err := ve.encodeBytes(original)
+    log.PanicIf(err)
+
+    // Now, pass the raw encoded value as if it was the entire addressable area
+    // and provide an offset of 0 as if it was a real block of data and this
+    // value happened to be recorded at the beginning.
+
+    ite := IfdTagEntry{
+        TagType: TypeByte,
+        UnitCount: uint32(len(original)),
+        ValueOffset: 0,
+    }
+
+    decodedBytes, err := ite.ValueBytes(ed.Encoded, byteOrder)
+    log.PanicIf(err)
+
+    if bytes.Compare(decodedBytes, original) != 0 {
+        t.Fatalf("Bytes not decoded correctly.")
+    }
+}
+
+func TestIfdTagEntry_ValueBytes_RealData(t *testing.T) {
+    defer func() {
+        if state := recover(); state != nil {
+            err := log.Wrap(state.(error))
+            log.PrintErrorf(err, "Test failure.")
+        }
+    }()
+
+    e := NewExif()
+
+    filepath := path.Join(assetsPath, "NDM_8901.jpg")
+
+    rawExif, err := e.SearchAndExtractExif(filepath)
+    log.PanicIf(err)
+
+    eh, index, err := e.Collect(rawExif)
+    log.PanicIf(err)
+
+    var ite *IfdTagEntry
+    for _, thisIte := range index.RootIfd.Entries {
+        if thisIte.TagId == 0x0110 {
+            ite = &thisIte
+            break
+        }
+    }
+
+    if ite == nil {
+        t.Fatalf("Tag not found.")
+    }
+
+    addressableData := rawExif[ExifAddressableAreaStart:]
+    decodedBytes, err := ite.ValueBytes(addressableData, eh.ByteOrder)
+    log.PanicIf(err)
+
+    expected := []byte("Canon EOS 5D Mark III")
+    expected = append(expected, 0)
+
+    if len(decodedBytes) != int(ite.UnitCount) {
+        t.Fatalf("Decoded bytes not the right count.")
+    } else if bytes.Compare(decodedBytes, expected) != 0 {
+        t.Fatalf("Decoded bytes not correct.")
+    }
+}
+
+func TestIfdTagEntry_Resolver_ValueBytes(t *testing.T) {
+    defer func() {
+        if state := recover(); state != nil {
+            err := log.Wrap(state.(error))
+            log.PrintErrorf(err, "Test failure.")
+        }
+    }()
+
+    e := NewExif()
+
+    filepath := path.Join(assetsPath, "NDM_8901.jpg")
+
+    rawExif, err := e.SearchAndExtractExif(filepath)
+    log.PanicIf(err)
+
+    eh, index, err := e.Collect(rawExif)
+    log.PanicIf(err)
+
+    var ite *IfdTagEntry
+    for _, thisIte := range index.RootIfd.Entries {
+        if thisIte.TagId == 0x0110 {
+            ite = &thisIte
+            break
+        }
+    }
+
+    if ite == nil {
+        t.Fatalf("Tag not found.")
+    }
+
+    itevr := NewIfdTagEntryValueResolver(rawExif, eh.ByteOrder)
+
+    decodedBytes, err := itevr.ValueBytes(ite)
+    log.PanicIf(err)
+
+    expected := []byte("Canon EOS 5D Mark III")
+    expected = append(expected, 0)
+
+    if len(decodedBytes) != int(ite.UnitCount) {
+        t.Fatalf("Decoded bytes not the right count.")
+    } else if bytes.Compare(decodedBytes, expected) != 0 {
+        t.Fatalf("Decoded bytes not correct.")
+    }
+}
+
+func TestIfdTagEntry_Resolver_ValueBytes__Unknown_Field_And_Nonroot_Ifd(t *testing.T) {
+    defer func() {
+        if state := recover(); state != nil {
+            err := log.Wrap(state.(error))
+            log.PrintErrorf(err, "Test failure.")
+        }
+    }()
+
+    e := NewExif()
+
+    filepath := path.Join(assetsPath, "NDM_8901.jpg")
+
+    rawExif, err := e.SearchAndExtractExif(filepath)
+    log.PanicIf(err)
+
+    eh, index, err := e.Collect(rawExif)
+    log.PanicIf(err)
+
+    ifdExif := index.Lookup[IfdExif][0]
+
+    var ite *IfdTagEntry
+    for _, thisIte := range ifdExif.Entries {
+        if thisIte.TagId == 0x9000 {
+            ite = &thisIte
+            break
+        }
+    }
+
+    if ite == nil {
+        t.Fatalf("Tag not found.")
+    }
+
+    itevr := NewIfdTagEntryValueResolver(rawExif, eh.ByteOrder)
+
+    decodedBytes, err := itevr.ValueBytes(ite)
+    log.PanicIf(err)
+
+    expected := []byte { '0', '2', '3', '0' }
+
+    if len(decodedBytes) != int(ite.UnitCount) {
+        t.Fatalf("Decoded bytes not the right count.")
+    } else if bytes.Compare(decodedBytes, expected) != 0 {
+        t.Fatalf("Recovered unknown value is not correct.")
+    }
+}

type_decode.go

@@ -601,6 +601,8 @@ func UndefinedValue(indexedIfdName string, tagId uint16, valueContext ValueConte
         }
     }()
 
+    typeDecodeLogger.Debugf(nil, "UndefinedValue: IFD=[%s] TAG-ID=(0x%02x)", indexedIfdName, tagId)
+
     if indexedIfdName == IfdName(IfdExif, 0) {
         if tagId == 0x9000 {
             // ExifVersion