diff options
Diffstat (limited to 'vendor/github.com/dsoprea/go-exif/ifd_builder_encode.go')
| -rw-r--r-- | vendor/github.com/dsoprea/go-exif/ifd_builder_encode.go | 530 |
1 files changed, 0 insertions, 530 deletions
diff --git a/vendor/github.com/dsoprea/go-exif/ifd_builder_encode.go b/vendor/github.com/dsoprea/go-exif/ifd_builder_encode.go deleted file mode 100644 index 90fb2ddbf..000000000 --- a/vendor/github.com/dsoprea/go-exif/ifd_builder_encode.go +++ /dev/null @@ -1,530 +0,0 @@ -package exif - -import ( - "bytes" - "fmt" - "strings" - - "encoding/binary" - - "github.com/dsoprea/go-logging" -) - -const ( - // Tag-ID + Tag-Type + Unit-Count + Value/Offset. - IfdTagEntrySize = uint32(2 + 2 + 4 + 4) -) - -type ByteWriter struct { - b *bytes.Buffer - byteOrder binary.ByteOrder -} - -func NewByteWriter(b *bytes.Buffer, byteOrder binary.ByteOrder) (bw *ByteWriter) { - return &ByteWriter{ - b: b, - byteOrder: byteOrder, - } -} - -func (bw ByteWriter) writeAsBytes(value interface{}) (err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - err = binary.Write(bw.b, bw.byteOrder, value) - log.PanicIf(err) - - return nil -} - -func (bw ByteWriter) WriteUint32(value uint32) (err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - err = bw.writeAsBytes(value) - log.PanicIf(err) - - return nil -} - -func (bw ByteWriter) WriteUint16(value uint16) (err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - err = bw.writeAsBytes(value) - log.PanicIf(err) - - return nil -} - -func (bw ByteWriter) WriteFourBytes(value []byte) (err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - len_ := len(value) - if len_ != 4 { - log.Panicf("value is not four-bytes: (%d)", len_) - } - - _, err = bw.b.Write(value) - log.PanicIf(err) - - return nil -} - -// ifdOffsetIterator keeps track of where the next IFD should be written by -// keeping track of where the offsets start, the data that has been added, and -// bumping the offset *when* the data is added. -type ifdDataAllocator struct { - offset uint32 - b bytes.Buffer -} - -func newIfdDataAllocator(ifdDataAddressableOffset uint32) *ifdDataAllocator { - return &ifdDataAllocator{ - offset: ifdDataAddressableOffset, - } -} - -func (ida *ifdDataAllocator) Allocate(value []byte) (offset uint32, err error) { - _, err = ida.b.Write(value) - log.PanicIf(err) - - offset = ida.offset - ida.offset += uint32(len(value)) - - return offset, nil -} - -func (ida *ifdDataAllocator) NextOffset() uint32 { - return ida.offset -} - -func (ida *ifdDataAllocator) Bytes() []byte { - return ida.b.Bytes() -} - -// IfdByteEncoder converts an IB to raw bytes (for writing) while also figuring -// out all of the allocations and indirection that is required for extended -// data. -type IfdByteEncoder struct { - // journal holds a list of actions taken while encoding. - journal [][3]string -} - -func NewIfdByteEncoder() (ibe *IfdByteEncoder) { - return &IfdByteEncoder{ - journal: make([][3]string, 0), - } -} - -func (ibe *IfdByteEncoder) Journal() [][3]string { - return ibe.journal -} - -func (ibe *IfdByteEncoder) TableSize(entryCount int) uint32 { - // Tag-Count + (Entry-Size * Entry-Count) + Next-IFD-Offset. - return uint32(2) + (IfdTagEntrySize * uint32(entryCount)) + uint32(4) -} - -func (ibe *IfdByteEncoder) pushToJournal(where, direction, format string, args ...interface{}) { - event := [3]string{ - direction, - where, - fmt.Sprintf(format, args...), - } - - ibe.journal = append(ibe.journal, event) -} - -// PrintJournal prints a hierarchical representation of the steps taken during -// encoding. -func (ibe *IfdByteEncoder) PrintJournal() { - maxWhereLength := 0 - for _, event := range ibe.journal { - where := event[1] - - len_ := len(where) - if len_ > maxWhereLength { - maxWhereLength = len_ - } - } - - level := 0 - for i, event := range ibe.journal { - direction := event[0] - where := event[1] - message := event[2] - - if direction != ">" && direction != "<" && direction != "-" { - log.Panicf("journal operation not valid: [%s]", direction) - } - - if direction == "<" { - if level <= 0 { - log.Panicf("journal operations unbalanced (too many closes)") - } - - level-- - } - - indent := strings.Repeat(" ", level) - - fmt.Printf("%3d %s%s %s: %s\n", i, indent, direction, where, message) - - if direction == ">" { - level++ - } - } - - if level != 0 { - log.Panicf("journal operations unbalanced (too many opens)") - } -} - -// encodeTagToBytes encodes the given tag to a byte stream. If -// `nextIfdOffsetToWrite` is more than (0), recurse into child IFDs -// (`nextIfdOffsetToWrite` is required in order for them to know where the its -// IFD data will be written, in order for them to know the offset of where -// their allocated-data block will start, which follows right behind). -func (ibe *IfdByteEncoder) encodeTagToBytes(ib *IfdBuilder, bt *BuilderTag, bw *ByteWriter, ida *ifdDataAllocator, nextIfdOffsetToWrite uint32) (childIfdBlock []byte, err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - // Write tag-ID. - err = bw.WriteUint16(bt.tagId) - log.PanicIf(err) - - // Works for both values and child IFDs (which have an official size of - // LONG). - err = bw.WriteUint16(uint16(bt.typeId)) - log.PanicIf(err) - - // Write unit-count. - - if bt.value.IsBytes() == true { - effectiveType := bt.typeId - if bt.typeId == TypeUndefined { - effectiveType = TypeByte - } - - // It's a non-unknown value.Calculate the count of values of - // the type that we're writing and the raw bytes for the whole list. - - typeSize := uint32(effectiveType.Size()) - - valueBytes := bt.value.Bytes() - - len_ := len(valueBytes) - unitCount := uint32(len_) / typeSize - - if _, found := tagsWithoutAlignment[bt.tagId]; found == false { - remainder := uint32(len_) % typeSize - - if remainder > 0 { - log.Panicf("tag (0x%04x) value of (%d) bytes not evenly divisible by type-size (%d)", bt.tagId, len_, typeSize) - } - } - - err = bw.WriteUint32(unitCount) - log.PanicIf(err) - - // Write four-byte value/offset. - - if len_ > 4 { - offset, err := ida.Allocate(valueBytes) - log.PanicIf(err) - - err = bw.WriteUint32(offset) - log.PanicIf(err) - } else { - fourBytes := make([]byte, 4) - copy(fourBytes, valueBytes) - - err = bw.WriteFourBytes(fourBytes) - log.PanicIf(err) - } - } else { - if bt.value.IsIb() == false { - log.Panicf("tag value is not a byte-slice but also not a child IB: %v", bt) - } - - // Write unit-count (one LONG representing one offset). - err = bw.WriteUint32(1) - log.PanicIf(err) - - if nextIfdOffsetToWrite > 0 { - var err error - - ibe.pushToJournal("encodeTagToBytes", ">", "[%s]->[%s]", ib.ifdPath, bt.value.Ib().ifdPath) - - // Create the block of IFD data and everything it requires. - childIfdBlock, err = ibe.encodeAndAttachIfd(bt.value.Ib(), nextIfdOffsetToWrite) - log.PanicIf(err) - - ibe.pushToJournal("encodeTagToBytes", "<", "[%s]->[%s]", bt.value.Ib().ifdPath, ib.ifdPath) - - // Use the next-IFD offset for it. The IFD will actually get - // attached after we return. - err = bw.WriteUint32(nextIfdOffsetToWrite) - log.PanicIf(err) - - } else { - // No child-IFDs are to be allocated. Finish the entry with a NULL - // pointer. - - ibe.pushToJournal("encodeTagToBytes", "-", "*Not* descending to child: [%s]", bt.value.Ib().ifdPath) - - err = bw.WriteUint32(0) - log.PanicIf(err) - } - } - - return childIfdBlock, nil -} - -// encodeIfdToBytes encodes the given IB to a byte-slice. We are given the -// offset at which this IFD will be written. This method is used called both to -// pre-determine how big the table is going to be (so that we can calculate the -// address to allocate data at) as well as to write the final table. -// -// It is necessary to fully realize the table in order to predetermine its size -// because it is not enough to know the size of the table: If there are child -// IFDs, we will not be able to allocate them without first knowing how much -// data we need to allocate for the current IFD. -func (ibe *IfdByteEncoder) encodeIfdToBytes(ib *IfdBuilder, ifdAddressableOffset uint32, nextIfdOffsetToWrite uint32, setNextIb bool) (data []byte, tableSize uint32, dataSize uint32, childIfdSizes []uint32, err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - ibe.pushToJournal("encodeIfdToBytes", ">", "%s", ib) - - tableSize = ibe.TableSize(len(ib.tags)) - - b := new(bytes.Buffer) - bw := NewByteWriter(b, ib.byteOrder) - - // Write tag count. - err = bw.WriteUint16(uint16(len(ib.tags))) - log.PanicIf(err) - - ida := newIfdDataAllocator(ifdAddressableOffset) - - childIfdBlocks := make([][]byte, 0) - - // Write raw bytes for each tag entry. Allocate larger data to be referred - // to in the follow-up data-block as required. Any "unknown"-byte tags that - // we can't parse will not be present here (using AddTagsFromExisting(), at - // least). - for _, bt := range ib.tags { - childIfdBlock, err := ibe.encodeTagToBytes(ib, bt, bw, ida, nextIfdOffsetToWrite) - log.PanicIf(err) - - if childIfdBlock != nil { - // We aren't allowed to have non-nil child IFDs if we're just - // sizing things up. - if nextIfdOffsetToWrite == 0 { - log.Panicf("no IFD offset provided for child-IFDs; no new child-IFDs permitted") - } - - nextIfdOffsetToWrite += uint32(len(childIfdBlock)) - childIfdBlocks = append(childIfdBlocks, childIfdBlock) - } - } - - dataBytes := ida.Bytes() - dataSize = uint32(len(dataBytes)) - - childIfdSizes = make([]uint32, len(childIfdBlocks)) - childIfdsTotalSize := uint32(0) - for i, childIfdBlock := range childIfdBlocks { - len_ := uint32(len(childIfdBlock)) - childIfdSizes[i] = len_ - childIfdsTotalSize += len_ - } - - // N the link from this IFD to the next IFD that will be written in the - // next cycle. - if setNextIb == true { - // Write address of next IFD in chain. This will be the original - // allocation offset plus the size of everything we have allocated for - // this IFD and its child-IFDs. - // - // It is critical that this number is stepped properly. We experienced - // an issue whereby it first looked like we were duplicating the IFD and - // then that we were duplicating the tags in the wrong IFD, and then - // finally we determined that the next-IFD offset for the first IFD was - // accidentally pointing back to the EXIF IFD, so we were visiting it - // twice when visiting through the tags after decoding. It was an - // expensive bug to find. - - ibe.pushToJournal("encodeIfdToBytes", "-", "Setting 'next' IFD to (0x%08x).", nextIfdOffsetToWrite) - - err := bw.WriteUint32(nextIfdOffsetToWrite) - log.PanicIf(err) - } else { - err := bw.WriteUint32(0) - log.PanicIf(err) - } - - _, err = b.Write(dataBytes) - log.PanicIf(err) - - // Append any child IFD blocks after our table and data blocks. These IFDs - // were equipped with the appropriate offset information so it's expected - // that all offsets referred to by these will be correct. - // - // Note that child-IFDs are append after the current IFD and before the - // next IFD, as opposed to the root IFDs, which are chained together but - // will be interrupted by these child-IFDs (which is expected, per the - // standard). - - for _, childIfdBlock := range childIfdBlocks { - _, err = b.Write(childIfdBlock) - log.PanicIf(err) - } - - ibe.pushToJournal("encodeIfdToBytes", "<", "%s", ib) - - return b.Bytes(), tableSize, dataSize, childIfdSizes, nil -} - -// encodeAndAttachIfd is a reentrant function that processes the IFD chain. -func (ibe *IfdByteEncoder) encodeAndAttachIfd(ib *IfdBuilder, ifdAddressableOffset uint32) (data []byte, err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - ibe.pushToJournal("encodeAndAttachIfd", ">", "%s", ib) - - b := new(bytes.Buffer) - - i := 0 - - for thisIb := ib; thisIb != nil; thisIb = thisIb.nextIb { - - // Do a dry-run in order to pre-determine its size requirement. - - ibe.pushToJournal("encodeAndAttachIfd", ">", "Beginning encoding process: (%d) [%s]", i, thisIb.ifdPath) - - ibe.pushToJournal("encodeAndAttachIfd", ">", "Calculating size: (%d) [%s]", i, thisIb.ifdPath) - - _, tableSize, allocatedDataSize, _, err := ibe.encodeIfdToBytes(thisIb, ifdAddressableOffset, 0, false) - log.PanicIf(err) - - ibe.pushToJournal("encodeAndAttachIfd", "<", "Finished calculating size: (%d) [%s]", i, thisIb.ifdPath) - - ifdAddressableOffset += tableSize - nextIfdOffsetToWrite := ifdAddressableOffset + allocatedDataSize - - ibe.pushToJournal("encodeAndAttachIfd", ">", "Next IFD will be written at offset (0x%08x)", nextIfdOffsetToWrite) - - // Write our IFD as well as any child-IFDs (now that we know the offset - // where new IFDs and their data will be allocated). - - setNextIb := thisIb.nextIb != nil - - ibe.pushToJournal("encodeAndAttachIfd", ">", "Encoding starting: (%d) [%s] NEXT-IFD-OFFSET-TO-WRITE=(0x%08x)", i, thisIb.ifdPath, nextIfdOffsetToWrite) - - tableAndAllocated, effectiveTableSize, effectiveAllocatedDataSize, childIfdSizes, err := - ibe.encodeIfdToBytes(thisIb, ifdAddressableOffset, nextIfdOffsetToWrite, setNextIb) - - log.PanicIf(err) - - if effectiveTableSize != tableSize { - log.Panicf("written table size does not match the pre-calculated table size: (%d) != (%d) %s", effectiveTableSize, tableSize, ib) - } else if effectiveAllocatedDataSize != allocatedDataSize { - log.Panicf("written allocated-data size does not match the pre-calculated allocated-data size: (%d) != (%d) %s", effectiveAllocatedDataSize, allocatedDataSize, ib) - } - - ibe.pushToJournal("encodeAndAttachIfd", "<", "Encoding done: (%d) [%s]", i, thisIb.ifdPath) - - totalChildIfdSize := uint32(0) - for _, childIfdSize := range childIfdSizes { - totalChildIfdSize += childIfdSize - } - - if len(tableAndAllocated) != int(tableSize+allocatedDataSize+totalChildIfdSize) { - log.Panicf("IFD table and data is not a consistent size: (%d) != (%d)", len(tableAndAllocated), tableSize+allocatedDataSize+totalChildIfdSize) - } - - // TODO(dustin): We might want to verify the original tableAndAllocated length, too. - - _, err = b.Write(tableAndAllocated) - log.PanicIf(err) - - // Advance past what we've allocated, thus far. - - ifdAddressableOffset += allocatedDataSize + totalChildIfdSize - - ibe.pushToJournal("encodeAndAttachIfd", "<", "Finishing encoding process: (%d) [%s] [FINAL:] NEXT-IFD-OFFSET-TO-WRITE=(0x%08x)", i, ib.ifdPath, nextIfdOffsetToWrite) - - i++ - } - - ibe.pushToJournal("encodeAndAttachIfd", "<", "%s", ib) - - return b.Bytes(), nil -} - -// EncodeToExifPayload is the base encoding step that transcribes the entire IB -// structure to its on-disk layout. -func (ibe *IfdByteEncoder) EncodeToExifPayload(ib *IfdBuilder) (data []byte, err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - data, err = ibe.encodeAndAttachIfd(ib, ExifDefaultFirstIfdOffset) - log.PanicIf(err) - - return data, nil -} - -// EncodeToExif calls EncodeToExifPayload and then packages the result into a -// complete EXIF block. -func (ibe *IfdByteEncoder) EncodeToExif(ib *IfdBuilder) (data []byte, err error) { - defer func() { - if state := recover(); state != nil { - err = log.Wrap(state.(error)) - } - }() - - encodedIfds, err := ibe.EncodeToExifPayload(ib) - log.PanicIf(err) - - // Wrap the IFD in a formal EXIF block. - - b := new(bytes.Buffer) - - headerBytes, err := BuildExifHeader(ib.byteOrder, ExifDefaultFirstIfdOffset) - log.PanicIf(err) - - _, err = b.Write(headerBytes) - log.PanicIf(err) - - _, err = b.Write(encodedIfds) - log.PanicIf(err) - - return b.Bytes(), nil -} |