mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-13 13:01:02 +00:00
416 lines
8.6 KiB
Go
416 lines
8.6 KiB
Go
package pngstructure
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
|
|
"encoding/binary"
|
|
"hash/crc32"
|
|
|
|
"github.com/dsoprea/go-exif/v3"
|
|
"github.com/dsoprea/go-exif/v3/common"
|
|
"github.com/dsoprea/go-logging"
|
|
"github.com/dsoprea/go-utility/v2/image"
|
|
)
|
|
|
|
var (
|
|
PngSignature = [8]byte{137, 'P', 'N', 'G', '\r', '\n', 26, '\n'}
|
|
EXifChunkType = "eXIf"
|
|
IHDRChunkType = "IHDR"
|
|
)
|
|
|
|
var (
|
|
ErrNotPng = errors.New("not png data")
|
|
ErrCrcFailure = errors.New("crc failure")
|
|
)
|
|
|
|
// ChunkSlice encapsulates a slice of chunks.
|
|
type ChunkSlice struct {
|
|
chunks []*Chunk
|
|
}
|
|
|
|
func NewChunkSlice(chunks []*Chunk) *ChunkSlice {
|
|
if len(chunks) == 0 {
|
|
log.Panicf("ChunkSlice must be initialized with at least one chunk (IHDR)")
|
|
} else if chunks[0].Type != IHDRChunkType {
|
|
log.Panicf("first chunk in any ChunkSlice must be an IHDR")
|
|
}
|
|
|
|
return &ChunkSlice{
|
|
chunks: chunks,
|
|
}
|
|
}
|
|
|
|
func NewPngChunkSlice() *ChunkSlice {
|
|
|
|
ihdrChunk := &Chunk{
|
|
Type: IHDRChunkType,
|
|
}
|
|
|
|
ihdrChunk.UpdateCrc32()
|
|
|
|
return NewChunkSlice([]*Chunk{ihdrChunk})
|
|
}
|
|
|
|
func (cs *ChunkSlice) String() string {
|
|
return fmt.Sprintf("ChunkSlize<LEN=(%d)>", len(cs.chunks))
|
|
}
|
|
|
|
// Chunks exposes the actual slice.
|
|
func (cs *ChunkSlice) Chunks() []*Chunk {
|
|
return cs.chunks
|
|
}
|
|
|
|
// Write encodes and writes all chunks.
|
|
func (cs *ChunkSlice) WriteTo(w io.Writer) (err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
_, err = w.Write(PngSignature[:])
|
|
log.PanicIf(err)
|
|
|
|
// TODO(dustin): !! This should respect the safe-to-copy characteristic.
|
|
for _, c := range cs.chunks {
|
|
_, err := c.WriteTo(w)
|
|
log.PanicIf(err)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Index returns a map of chunk types to chunk slices, grouping all like chunks.
|
|
func (cs *ChunkSlice) Index() (index map[string][]*Chunk) {
|
|
index = make(map[string][]*Chunk)
|
|
for _, c := range cs.chunks {
|
|
if grouped, found := index[c.Type]; found == true {
|
|
index[c.Type] = append(grouped, c)
|
|
} else {
|
|
index[c.Type] = []*Chunk{c}
|
|
}
|
|
}
|
|
|
|
return index
|
|
}
|
|
|
|
// FindExif returns the the segment that hosts the EXIF data.
|
|
func (cs *ChunkSlice) FindExif() (chunk *Chunk, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
index := cs.Index()
|
|
|
|
if chunks, found := index[EXifChunkType]; found == true {
|
|
return chunks[0], nil
|
|
}
|
|
|
|
log.Panic(exif.ErrNoExif)
|
|
|
|
// Never called.
|
|
return nil, nil
|
|
}
|
|
|
|
// Exif returns an `exif.Ifd` instance with the existing tags.
|
|
func (cs *ChunkSlice) Exif() (rootIfd *exif.Ifd, data []byte, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
chunk, err := cs.FindExif()
|
|
log.PanicIf(err)
|
|
|
|
im, err := exifcommon.NewIfdMappingWithStandard()
|
|
log.PanicIf(err)
|
|
|
|
ti := exif.NewTagIndex()
|
|
|
|
// TODO(dustin): Refactor and support `exif.GetExifData()`.
|
|
|
|
_, index, err := exif.Collect(im, ti, chunk.Data)
|
|
log.PanicIf(err)
|
|
|
|
return index.RootIfd, chunk.Data, nil
|
|
}
|
|
|
|
// ConstructExifBuilder returns an `exif.IfdBuilder` instance (needed for
|
|
// modifying) preloaded with all existing tags.
|
|
func (cs *ChunkSlice) ConstructExifBuilder() (rootIb *exif.IfdBuilder, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
rootIfd, _, err := cs.Exif()
|
|
log.PanicIf(err)
|
|
|
|
ib := exif.NewIfdBuilderFromExistingChain(rootIfd)
|
|
|
|
return ib, nil
|
|
}
|
|
|
|
// SetExif encodes and sets EXIF data into this segment.
|
|
func (cs *ChunkSlice) SetExif(ib *exif.IfdBuilder) (err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
// Encode.
|
|
|
|
ibe := exif.NewIfdByteEncoder()
|
|
|
|
exifData, err := ibe.EncodeToExif(ib)
|
|
log.PanicIf(err)
|
|
|
|
// Set.
|
|
|
|
exifChunk, err := cs.FindExif()
|
|
if err == nil {
|
|
// EXIF chunk already exists.
|
|
|
|
exifChunk.Data = exifData
|
|
exifChunk.Length = uint32(len(exifData))
|
|
} else {
|
|
if log.Is(err, exif.ErrNoExif) != true {
|
|
log.Panic(err)
|
|
}
|
|
|
|
// Add a EXIF chunk for the first time.
|
|
|
|
exifChunk = &Chunk{
|
|
Type: EXifChunkType,
|
|
Data: exifData,
|
|
Length: uint32(len(exifData)),
|
|
}
|
|
|
|
// Insert it after the IHDR chunk (it's a reliably appropriate place to
|
|
// put it).
|
|
cs.chunks = append(cs.chunks[:1], append([]*Chunk{exifChunk}, cs.chunks[1:]...)...)
|
|
}
|
|
|
|
exifChunk.UpdateCrc32()
|
|
|
|
return nil
|
|
}
|
|
|
|
// PngSplitter hosts the princpal `Split()` method uses by `bufio.Scanner`.
|
|
type PngSplitter struct {
|
|
chunks []*Chunk
|
|
currentOffset int
|
|
|
|
doCheckCrc bool
|
|
crcErrors []string
|
|
}
|
|
|
|
func (ps *PngSplitter) Chunks() *ChunkSlice {
|
|
return NewChunkSlice(ps.chunks)
|
|
}
|
|
|
|
func (ps *PngSplitter) DoCheckCrc(doCheck bool) {
|
|
ps.doCheckCrc = doCheck
|
|
}
|
|
|
|
func (ps *PngSplitter) CrcErrors() []string {
|
|
return ps.crcErrors
|
|
}
|
|
|
|
func NewPngSplitter() *PngSplitter {
|
|
return &PngSplitter{
|
|
chunks: make([]*Chunk, 0),
|
|
doCheckCrc: true,
|
|
crcErrors: make([]string, 0),
|
|
}
|
|
}
|
|
|
|
// Chunk describes a single chunk.
|
|
type Chunk struct {
|
|
Offset int
|
|
Length uint32
|
|
Type string
|
|
Data []byte
|
|
Crc uint32
|
|
}
|
|
|
|
func (c *Chunk) String() string {
|
|
return fmt.Sprintf("Chunk<OFFSET=(%d) LENGTH=(%d) TYPE=[%s] CRC=(%d)>", c.Offset, c.Length, c.Type, c.Crc)
|
|
}
|
|
|
|
func calculateCrc32(chunk *Chunk) uint32 {
|
|
c := crc32.NewIEEE()
|
|
|
|
c.Write([]byte(chunk.Type))
|
|
c.Write(chunk.Data)
|
|
|
|
return c.Sum32()
|
|
}
|
|
|
|
func (c *Chunk) UpdateCrc32() {
|
|
c.Crc = calculateCrc32(c)
|
|
}
|
|
|
|
func (c *Chunk) CheckCrc32() bool {
|
|
expected := calculateCrc32(c)
|
|
return c.Crc == expected
|
|
}
|
|
|
|
// Bytes encodes and returns the bytes for this chunk.
|
|
func (c *Chunk) Bytes() []byte {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err := log.Wrap(state.(error))
|
|
log.Panic(err)
|
|
}
|
|
}()
|
|
|
|
if len(c.Data) != int(c.Length) {
|
|
log.Panicf("length of data not correct")
|
|
}
|
|
|
|
preallocated := make([]byte, 0, 4+4+c.Length+4)
|
|
b := bytes.NewBuffer(preallocated)
|
|
|
|
err := binary.Write(b, binary.BigEndian, c.Length)
|
|
log.PanicIf(err)
|
|
|
|
_, err = b.Write([]byte(c.Type))
|
|
log.PanicIf(err)
|
|
|
|
if c.Data != nil {
|
|
_, err = b.Write(c.Data)
|
|
log.PanicIf(err)
|
|
}
|
|
|
|
err = binary.Write(b, binary.BigEndian, c.Crc)
|
|
log.PanicIf(err)
|
|
|
|
return b.Bytes()
|
|
}
|
|
|
|
// Write encodes and writes the bytes for this chunk.
|
|
func (c *Chunk) WriteTo(w io.Writer) (count int, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
if len(c.Data) != int(c.Length) {
|
|
log.Panicf("length of data not correct")
|
|
}
|
|
|
|
err = binary.Write(w, binary.BigEndian, c.Length)
|
|
log.PanicIf(err)
|
|
|
|
_, err = w.Write([]byte(c.Type))
|
|
log.PanicIf(err)
|
|
|
|
_, err = w.Write(c.Data)
|
|
log.PanicIf(err)
|
|
|
|
err = binary.Write(w, binary.BigEndian, c.Crc)
|
|
log.PanicIf(err)
|
|
|
|
return 4 + len(c.Type) + len(c.Data) + 4, nil
|
|
}
|
|
|
|
// readHeader verifies that the PNG header bytes appear next.
|
|
func (ps *PngSplitter) readHeader(r io.Reader) (err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
len_ := len(PngSignature)
|
|
header := make([]byte, len_)
|
|
|
|
_, err = r.Read(header)
|
|
log.PanicIf(err)
|
|
|
|
ps.currentOffset += len_
|
|
|
|
if bytes.Compare(header, PngSignature[:]) != 0 {
|
|
log.Panic(ErrNotPng)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Split fulfills the `bufio.SplitFunc` function definition for
|
|
// `bufio.Scanner`.
|
|
func (ps *PngSplitter) Split(data []byte, atEOF bool) (advance int, token []byte, err error) {
|
|
defer func() {
|
|
if state := recover(); state != nil {
|
|
err = log.Wrap(state.(error))
|
|
}
|
|
}()
|
|
|
|
// We might have more than one chunk's worth, and, if `atEOF` is true, we
|
|
// won't be called again. We'll repeatedly try to read additional chunks,
|
|
// but, when we run out of the data we were given then we'll return the
|
|
// number of bytes fo rthe chunks we've already completely read. Then,
|
|
// we'll be called again from theend ofthose bytes, at which point we'll
|
|
// indicate that we don't yet have enough for another chunk, and we should
|
|
// be then called with more.
|
|
for {
|
|
len_ := len(data)
|
|
if len_ < 8 {
|
|
return advance, nil, nil
|
|
}
|
|
|
|
length := binary.BigEndian.Uint32(data[:4])
|
|
type_ := string(data[4:8])
|
|
chunkSize := (8 + int(length) + 4)
|
|
|
|
if len_ < chunkSize {
|
|
return advance, nil, nil
|
|
}
|
|
|
|
crcIndex := 8 + length
|
|
crc := binary.BigEndian.Uint32(data[crcIndex : crcIndex+4])
|
|
|
|
content := make([]byte, length)
|
|
copy(content, data[8:8+length])
|
|
|
|
c := &Chunk{
|
|
Length: length,
|
|
Type: type_,
|
|
Data: content,
|
|
Crc: crc,
|
|
Offset: ps.currentOffset,
|
|
}
|
|
|
|
ps.chunks = append(ps.chunks, c)
|
|
|
|
if c.CheckCrc32() == false {
|
|
ps.crcErrors = append(ps.crcErrors, type_)
|
|
|
|
if ps.doCheckCrc == true {
|
|
log.Panic(ErrCrcFailure)
|
|
}
|
|
}
|
|
|
|
advance += chunkSize
|
|
ps.currentOffset += chunkSize
|
|
|
|
data = data[chunkSize:]
|
|
}
|
|
|
|
return advance, nil, nil
|
|
}
|
|
|
|
var (
|
|
// Enforce interface conformance.
|
|
_ riimage.MediaContext = new(ChunkSlice)
|
|
)
|