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* use pipereader + pipewriter * test updates * testing visitor function * hey it works * pngs working * rename license
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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, | ||
|
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||
| // 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, | ||
|
|
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| // J2C extensions | ||
| 0x74: 4, | ||
| 0x75: 4, | ||
| 0x77: 4, | ||
| } | ||
|
|
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| type jpegVisitor struct { | ||
| js *jpegstructure.JpegSplitter | ||
| writer io.Writer | ||
| } | ||
|
|
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| // 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) | ||
| } | ||
|
|
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| 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 | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,93 @@ | ||
| /* | ||
| 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" | ||
| "io" | ||
|
|
||
| pngstructure "github.com/dsoprea/go-png-image-structure/v2" | ||
| ) | ||
|
|
||
| type pngVisitor struct { | ||
| ps *pngstructure.PngSplitter | ||
| writer io.Writer | ||
| lastWrittenChunk int | ||
| } | ||
|
|
||
| func (v *pngVisitor) split(data []byte, atEOF bool) (int, []byte, error) { | ||
| // execute the ps split function to read in data | ||
| advance, token, err := v.ps.Split(data, atEOF) | ||
| if err != nil { | ||
| return advance, token, err | ||
| } | ||
|
|
||
| // if we haven't written anything at all yet, then write the png header back into the writer first | ||
| if v.lastWrittenChunk == -1 { | ||
| if _, err := v.writer.Write(pngstructure.PngSignature[:]); err != nil { | ||
| return advance, token, err | ||
| } | ||
| } | ||
|
|
||
| // check if the splitter has any new chunks in it that we haven't written yet | ||
| chunkSlice := v.ps.Chunks() | ||
| chunks := chunkSlice.Chunks() | ||
| for i, chunk := range chunks { | ||
| // look through all the chunks in the splitter | ||
| if i > v.lastWrittenChunk { | ||
| // we've got a chunk we haven't written yet! write it... | ||
| if err := v.writeChunk(chunk); err != nil { | ||
| return advance, token, err | ||
| } | ||
| // then remove the data | ||
| chunk.Data = chunk.Data[:0] | ||
| // and update | ||
| v.lastWrittenChunk = i | ||
| } | ||
| } | ||
|
|
||
| return advance, token, err | ||
| } | ||
|
|
||
| func (v *pngVisitor) writeChunk(chunk *pngstructure.Chunk) error { | ||
| if err := binary.Write(v.writer, binary.BigEndian, chunk.Length); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| if _, err := v.writer.Write([]byte(chunk.Type)); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| if chunk.Type == pngstructure.EXifChunkType { | ||
| blank := make([]byte, len(chunk.Data)) | ||
| if _, err := v.writer.Write(blank); err != nil { | ||
| return err | ||
| } | ||
| } else { | ||
| if _, err := v.writer.Write(chunk.Data); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
||
| if err := binary.Write(v.writer, binary.BigEndian, chunk.Crc); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| return nil | ||
| } |
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