diff options
Diffstat (limited to 'vendor/codeberg.org/superseriousbusiness/exif-terminator/jpeg.go')
| -rw-r--r-- | vendor/codeberg.org/superseriousbusiness/exif-terminator/jpeg.go | 295 |
1 files changed, 0 insertions, 295 deletions
diff --git a/vendor/codeberg.org/superseriousbusiness/exif-terminator/jpeg.go b/vendor/codeberg.org/superseriousbusiness/exif-terminator/jpeg.go deleted file mode 100644 index 576c4e430..000000000 --- a/vendor/codeberg.org/superseriousbusiness/exif-terminator/jpeg.go +++ /dev/null @@ -1,295 +0,0 @@ -/* - exif-terminator - Copyright (C) 2022 SuperSeriousBusiness admin@gotosocial.org - - This program is free software: you can redistribute it and/or modify - it under the terms of the GNU Affero General Public License as published by - the Free Software Foundation, either version 3 of the License, or - (at your option) any later version. - - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU Affero General Public License for more details. - - You should have received a copy of the GNU Affero General Public License - along with this program. If not, see <http://www.gnu.org/licenses/>. -*/ - -package terminator - -import ( - "bytes" - "encoding/binary" - "fmt" - "io" - - exif "github.com/dsoprea/go-exif/v3" - jpegstructure "github.com/superseriousbusiness/go-jpeg-image-structure/v2" -) - -var markerLen = map[byte]int{ - 0x00: 0, - 0x01: 0, - 0xd0: 0, - 0xd1: 0, - 0xd2: 0, - 0xd3: 0, - 0xd4: 0, - 0xd5: 0, - 0xd6: 0, - 0xd7: 0, - 0xd8: 0, - 0xd9: 0, - 0xda: 0, - - // J2C - 0x30: 0, - 0x31: 0, - 0x32: 0, - 0x33: 0, - 0x34: 0, - 0x35: 0, - 0x36: 0, - 0x37: 0, - 0x38: 0, - 0x39: 0, - 0x3a: 0, - 0x3b: 0, - 0x3c: 0, - 0x3d: 0, - 0x3e: 0, - 0x3f: 0, - 0x4f: 0, - 0x92: 0, - 0x93: 0, - - // J2C extensions - 0x74: 4, - 0x75: 4, - 0x77: 4, -} - -type jpegVisitor struct { - js *jpegstructure.JpegSplitter - writer io.Writer - expectedFileSize int - writtenTotalBytes int -} - -// HandleSegment satisfies the visitor interface{} of the jpegstructure library. -// -// We don't really care about many of the parameters, since all we're interested -// in here is the very last segment that was scanned. -func (v *jpegVisitor) HandleSegment(segmentMarker byte, _ string, _ int, _ bool) error { - // get the most recent segment scanned (ie., last in the segments list) - segmentList := v.js.Segments() - segments := segmentList.Segments() - mostRecentSegment := segments[len(segments)-1] - - // check if we've written the expected number of bytes by EOI - if segmentMarker == jpegstructure.MARKER_EOI { - // take account of the last 2 bytes taken up by the EOI - eoiLength := 2 - - // this is the total file size we will - // have written including the EOI - willHaveWritten := v.writtenTotalBytes + eoiLength - - if willHaveWritten < v.expectedFileSize { - // if we won't have written enough, - // pad the final segment before EOI - // so that we meet expected file size - missingBytes := make([]byte, v.expectedFileSize-willHaveWritten) - if _, err := v.writer.Write(missingBytes); err != nil { - return err - } - } - } - - // process the segment - return v.writeSegment(mostRecentSegment) -} - -func (v *jpegVisitor) writeSegment(s *jpegstructure.Segment) error { - var writtenSegmentData int - w := v.writer - - defer func() { - // whatever happens, when we finished then evict data from the segment; - // once we've written it we don't want it in memory anymore - s.Data = s.Data[:0] - }() - - // The scan-data will have a marker-ID of (0) because it doesn't have a marker-ID or length. - if s.MarkerId != 0 { - markerIDWritten, err := w.Write([]byte{0xff, s.MarkerId}) - if err != nil { - return err - } - writtenSegmentData += markerIDWritten - - sizeLen, found := markerLen[s.MarkerId] - if !found || sizeLen == 2 { - sizeLen = 2 - l := uint16(len(s.Data) + sizeLen) - - if err := binary.Write(w, binary.BigEndian, &l); err != nil { - return err - } - - writtenSegmentData += 2 - } else if sizeLen == 4 { - l := uint32(len(s.Data) + sizeLen) - - if err := binary.Write(w, binary.BigEndian, &l); err != nil { - return err - } - - writtenSegmentData += 4 - } else if sizeLen != 0 { - return fmt.Errorf("not a supported marker-size: MARKER-ID=(0x%02x) MARKER-SIZE-LEN=(%d)", s.MarkerId, sizeLen) - } - } - - if !s.IsExif() { - // if this isn't exif data just copy it over and bail - writtenNormalData, err := w.Write(s.Data) - if err != nil { - return err - } - - writtenSegmentData += writtenNormalData - v.writtenTotalBytes += writtenSegmentData - return nil - } - - ifd, _, err := s.Exif() - if err != nil { - return err - } - - // amount of bytes we've writtenExifData into the exif body, we'll update this as we go - var writtenExifData int - - if orientationEntries, err := ifd.FindTagWithName("Orientation"); err == nil && len(orientationEntries) == 1 { - // If we have an orientation entry, we don't want to completely obliterate the exif data. - // Instead, we want to surgically obliterate everything *except* the orientation tag, so - // that the image will still be rotated correctly when shown in client applications etc. - // - // To accomplish this, we're going to extract just the bytes that we need and write them - // in according to the exif specification, then fill in the rest of the space with empty - // bytes. - // - // First we need to write the exif prefix for this segment. - // - // Then we write the exif header which contains the byte order and offset of the first ifd. - // - // Then we write the ifd0 entry which contains the orientation data. - // - // After that we just fill. - - newExifData := &bytes.Buffer{} - byteOrder := ifd.ByteOrder() - - // 1. Write exif prefix. - // https://www.ozhiker.com/electronics/pjmt/jpeg_info/app_segments.html - prefix := []byte{'E', 'x', 'i', 'f', 0, 0} - if err := binary.Write(newExifData, byteOrder, &prefix); err != nil { - return err - } - writtenExifData += len(prefix) - - // 2. Write exif header, taking the existing byte order. - exifHeader, err := exif.BuildExifHeader(byteOrder, exif.ExifDefaultFirstIfdOffset) - if err != nil { - return err - } - hWritten, err := newExifData.Write(exifHeader) - if err != nil { - return err - } - writtenExifData += hWritten - - // 3. Write in the new ifd - // - // An ifd with one orientation entry is structured like this: - // 2 bytes: the number of entries in the ifd uint16(1) - // 2 bytes: the tag id uint16(274) - // 2 bytes: the tag type uint16(3) - // 4 bytes: the tag count uint32(1) - // 4 bytes: the tag value offset: uint32(one of the below with padding on the end) - // 1 = Horizontal (normal) - // 2 = Mirror horizontal - // 3 = Rotate 180 - // 4 = Mirror vertical - // 5 = Mirror horizontal and rotate 270 CW - // 6 = Rotate 90 CW - // 7 = Mirror horizontal and rotate 90 CW - // 8 = Rotate 270 CW - // - // see https://web.archive.org/web/20190624045241if_/http://www.cipa.jp:80/std/documents/e/DC-008-Translation-2019-E.pdf - p24-25 - orientationEntry := orientationEntries[0] - - ifdCount := uint16(1) // we're only adding one entry into the ifd - if err := binary.Write(newExifData, byteOrder, &ifdCount); err != nil { - return err - } - writtenExifData += 2 - - tagID := orientationEntry.TagId() - if err := binary.Write(newExifData, byteOrder, &tagID); err != nil { - return err - } - writtenExifData += 2 - - tagType := uint16(orientationEntry.TagType()) - if err := binary.Write(newExifData, byteOrder, &tagType); err != nil { - return err - } - writtenExifData += 2 - - tagCount := orientationEntry.UnitCount() - if err := binary.Write(newExifData, byteOrder, &tagCount); err != nil { - return err - } - writtenExifData += 4 - - valueOffset, err := orientationEntry.GetRawBytes() - if err != nil { - return err - } - - vWritten, err := newExifData.Write(valueOffset) - if err != nil { - return err - } - writtenExifData += vWritten - - valuePad := make([]byte, 4-vWritten) - pWritten, err := newExifData.Write(valuePad) - if err != nil { - return err - } - writtenExifData += pWritten - - // write all the new data into the writer from the segment - writtenNewExifData, err := io.Copy(w, newExifData) - if err != nil { - return err - } - - writtenSegmentData += int(writtenNewExifData) - } - - // fill in any remaining exif body with blank bytes - blank := make([]byte, len(s.Data)-writtenExifData) - writtenPadding, err := w.Write(blank) - if err != nil { - return err - } - - writtenSegmentData += writtenPadding - v.writtenTotalBytes += writtenSegmentData - return nil -} |