133 lines
2.9 KiB
Go
133 lines
2.9 KiB
Go
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/*
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exif-terminator
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Copyright (C) 2022 SuperSeriousBusiness admin@gotosocial.org
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package terminator
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import (
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"encoding/binary"
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"fmt"
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"io"
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jpegstructure "github.com/superseriousbusiness/go-jpeg-image-structure/v2"
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)
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var markerLen = map[byte]int{
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0x00: 0,
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0x01: 0,
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0xd0: 0,
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0xd1: 0,
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0xd2: 0,
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0xd3: 0,
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0xd4: 0,
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0xd5: 0,
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0xd6: 0,
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0xd7: 0,
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0xd8: 0,
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0xd9: 0,
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0xda: 0,
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// J2C
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0x30: 0,
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0x31: 0,
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0x32: 0,
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0x33: 0,
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0x34: 0,
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0x35: 0,
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0x36: 0,
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0x37: 0,
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0x38: 0,
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0x39: 0,
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0x3a: 0,
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0x3b: 0,
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0x3c: 0,
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0x3d: 0,
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0x3e: 0,
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0x3f: 0,
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0x4f: 0,
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0x92: 0,
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0x93: 0,
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// J2C extensions
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0x74: 4,
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0x75: 4,
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0x77: 4,
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}
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type jpegVisitor struct {
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js *jpegstructure.JpegSplitter
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writer io.Writer
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}
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// HandleSegment satisfies the visitor interface{} of the jpegstructure library.
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//
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// We don't really care about many of the parameters, since all we're interested
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// in here is the very last segment that was scanned.
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func (v *jpegVisitor) HandleSegment(segmentMarker byte, _ string, _ int, _ bool) error {
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segmentList := v.js.Segments()
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segments := segmentList.Segments()
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mostRecentSegment := segments[len(segments)-1]
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return v.writeSegment(mostRecentSegment)
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}
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func (v *jpegVisitor) writeSegment(s *jpegstructure.Segment) error {
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w := v.writer
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defer func() {
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// whatever happens, when we finished then evict data from the segment;
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// once we've written it we don't want it in memory anymore
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s.Data = nil
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}()
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if s.IsExif() {
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// Segment contains exif data, terminate!
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if err := terminateEXIF(s); err != nil {
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return err
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}
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}
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// The scan-data will have a marker-ID of (0) because it doesn't have a marker-ID or length.
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if s.MarkerId != 0 {
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_, err := w.Write([]byte{0xff, s.MarkerId})
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if err != nil {
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return err
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}
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sizeLen, found := markerLen[s.MarkerId]
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if !found || sizeLen == 2 {
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sizeLen = 2
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l := uint16(len(s.Data) + sizeLen)
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if err := binary.Write(w, binary.BigEndian, &l); err != nil {
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return err
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}
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} else if sizeLen == 4 {
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l := uint32(len(s.Data) + sizeLen)
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if err := binary.Write(w, binary.BigEndian, &l); err != nil {
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return err
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}
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} else if sizeLen != 0 {
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return fmt.Errorf("not a supported marker-size: MARKER-ID=(0x%02x) MARKER-SIZE-LEN=(%d)", s.MarkerId, sizeLen)
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}
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}
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_, err := w.Write(s.Data)
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return err
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}
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