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https://github.com/superseriousbusiness/gotosocial.git
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94e87610c4
* add back exif-terminator and use only for jpeg,png,webp * fix arguments passed to terminateExif() * pull in latest exif-terminator * fix test * update processed img --------- Co-authored-by: tobi <tobi.smethurst@protonmail.com>
147 lines
3.8 KiB
Go
147 lines
3.8 KiB
Go
/*
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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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"bufio"
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"bytes"
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"errors"
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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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pngstructure "github.com/superseriousbusiness/go-png-image-structure/v2"
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)
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func Terminate(in io.Reader, mediaType string) (io.Reader, error) {
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// To avoid keeping too much stuff
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// in memory we want to pipe data
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// directly to the reader.
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pr, pw := io.Pipe()
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// Setup scanner to terminate exif into pipe writer.
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scanner, err := terminatingScanner(pw, in, mediaType)
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if err != nil {
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_ = pw.Close()
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return nil, err
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}
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go func() {
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var err error
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defer func() {
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// Always close writer, using returned
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// scanner error (if any). If err is nil
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// then the standard io.EOF will be used.
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// (this will not overwrite existing).
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pw.CloseWithError(err)
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}()
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// Scan through input.
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for scanner.Scan() {
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}
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// Set error on return.
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err = scanner.Err()
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}()
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return pr, nil
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}
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func TerminateInto(out io.Writer, in io.Reader, mediaType string) error {
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// Setup scanner to terminate exif from 'in' to 'out'.
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scanner, err := terminatingScanner(out, in, mediaType)
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if err != nil {
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return err
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}
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// Scan through input.
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for scanner.Scan() {
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}
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// Return scan errors.
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return scanner.Err()
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}
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func terminatingScanner(out io.Writer, in io.Reader, mediaType string) (*bufio.Scanner, error) {
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scanner := bufio.NewScanner(in)
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// 40mb buffer size should be enough
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// to scan through most file chunks
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// without running into issues, they're
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// usually chunked smaller than this...
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scanner.Buffer(nil, 40*1024*1024)
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switch mediaType {
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case "image/jpeg", "jpeg", "jpg":
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v := &jpegVisitor{
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writer: out,
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}
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// Provide the visitor to the splitter so
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// that it triggers on every section scan.
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js := jpegstructure.NewJpegSplitter(v)
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// The visitor also needs to read back the
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// list of segments: for this it needs to
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// know what jpeg splitter it's attached to,
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// so give it a pointer to the splitter.
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v.js = js
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// Jpeg visitor's 'split' function
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// satisfies bufio.SplitFunc{}.
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scanner.Split(js.Split)
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case "image/webp", "webp":
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// Webp visitor's 'split' function
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// satisfies bufio.SplitFunc{}.
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scanner.Split((&webpVisitor{
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writer: out,
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}).split)
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case "image/png", "png":
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// For pngs we need to skip the header bytes, so read
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// them in and check we're really dealing with a png.
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header := make([]byte, len(pngstructure.PngSignature))
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if _, headerError := in.Read(header); headerError != nil {
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return nil, headerError
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} else if !bytes.Equal(header, pngstructure.PngSignature[:]) {
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return nil, errors.New("could not decode png: invalid header")
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}
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// Don't bother checking CRC;
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// we're overwriting it anyway.
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ps := pngstructure.NewPngSplitter()
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ps.DoCheckCrc(false)
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// Png visitor's 'split' function
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// satisfies bufio.SplitFunc{}.
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scanner.Split((&pngVisitor{
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ps: ps,
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writer: out,
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lastWrittenChunk: -1,
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}).split)
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default:
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return nil, fmt.Errorf("mediaType %s cannot be processed", mediaType)
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}
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return scanner, nil
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}
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