1 files changed, 138 insertions, 0 deletions
diff --git a/vendor/github.com/superseriousbusiness/exif-terminator/jpeg.go b/vendor/github.com/superseriousbusiness/exif-terminator/jpeg.go
new file mode 100644
index 000000000..224a9b646
--- /dev/null
+++ b/vendor/github.com/superseriousbusiness/exif-terminator/jpeg.go
@@ -0,0 +1,138 @@
+/*
+   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 (
+	"encoding/binary"
+	"fmt"
+	"io"
+
+	jpegstructure "github.com/dsoprea/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
+}
+
+// HandleSegment satisfies the visitor interface{} of the jpegstructure library.
+//
+// We don't really care about any of the parameters, since all we're interested
+// in here is the very last segment that was scanned.
+func (v *jpegVisitor) HandleSegment(_ byte, _ string, _ int, _ bool) error {
+	// all we want to do here is get the last segment that was scanned, and then manipulate it
+	segmentList := v.js.Segments()
+	segments := segmentList.Segments()
+	lastSegment := segments[len(segments)-1]
+	return v.writeSegment(lastSegment)
+}
+
+func (v *jpegVisitor) writeSegment(s *jpegstructure.Segment) error {
+	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 {
+		if _, err := w.Write([]byte{0xff, s.MarkerId}); err != nil {
+			return err
+		}
+
+		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
+			}
+
+		} else if sizeLen == 4 {
+			l := uint32(len(s.Data) + sizeLen)
+
+			if err := binary.Write(w, binary.BigEndian, &l); err != nil {
+				return err
+			}
+
+		} 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 segment is exif data, write blank bytes
+		blank := make([]byte, len(s.Data))
+		if _, err := w.Write(blank); err != nil {
+			return err
+		}
+	} else {
+		// otherwise write the data
+		if _, err := w.Write(s.Data); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}