mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-27 09:36:31 +00:00
110 lines
2.2 KiB
Go
110 lines
2.2 KiB
Go
/*
|
|
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"
|
|
"errors"
|
|
"io"
|
|
)
|
|
|
|
const (
|
|
riffHeader = "RIFF"
|
|
webpHeader = "WEBP"
|
|
exifFourcc = "EXIF"
|
|
xmpFourcc = "XMP "
|
|
)
|
|
|
|
var (
|
|
errNoRiffHeader = errors.New("no RIFF header")
|
|
errNoWebpHeader = errors.New("not a WEBP file")
|
|
errInvalidChunk = errors.New("invalid chunk")
|
|
)
|
|
|
|
type webpVisitor struct {
|
|
writer io.Writer
|
|
doneHeader bool
|
|
}
|
|
|
|
func (v *webpVisitor) split(data []byte, atEOF bool) (advance int, token []byte, err error) {
|
|
// parse/write the header first
|
|
if !v.doneHeader {
|
|
|
|
// const rifHeaderSize = 12
|
|
if len(data) < 12 {
|
|
if atEOF {
|
|
err = errNoRiffHeader
|
|
}
|
|
return
|
|
}
|
|
|
|
if string(data[:4]) != riffHeader {
|
|
err = errNoRiffHeader
|
|
return
|
|
}
|
|
|
|
if string(data[8:12]) != webpHeader {
|
|
err = errNoWebpHeader
|
|
return
|
|
}
|
|
|
|
if _, err = v.writer.Write(data[:12]); err != nil {
|
|
return
|
|
}
|
|
|
|
advance += 12
|
|
data = data[12:]
|
|
v.doneHeader = true
|
|
}
|
|
|
|
for {
|
|
// need enough for
|
|
// fourcc and size
|
|
if len(data) < 8 {
|
|
return
|
|
}
|
|
|
|
size := int64(binary.LittleEndian.Uint32(data[4:]))
|
|
|
|
if (size & 1) != 0 {
|
|
// odd chunk size:
|
|
// extra padding byte
|
|
size++
|
|
}
|
|
|
|
// wait until there is enough
|
|
if int64(len(data)) < 8+size {
|
|
return
|
|
}
|
|
|
|
// replace exif/xmp with blank
|
|
switch string(data[:4]) {
|
|
case exifFourcc, xmpFourcc:
|
|
clear(data[8 : 8+size])
|
|
}
|
|
|
|
if _, err = v.writer.Write(data[:8+size]); err != nil {
|
|
return
|
|
}
|
|
|
|
advance += 8 + int(size)
|
|
data = data[8+size:]
|
|
}
|
|
}
|