mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-05 10:02:47 +00:00
284 lines
6.3 KiB
Go
284 lines
6.3 KiB
Go
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// GoToSocial
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// Copyright (C) GoToSocial Authors admin@gotosocial.org
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// SPDX-License-Identifier: AGPL-3.0-or-later
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//
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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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//
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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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//
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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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package media
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import (
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"context"
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"encoding/binary"
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"image/jpeg"
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"io"
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"os"
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"strings"
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"codeberg.org/gruf/go-byteutil"
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"github.com/superseriousbusiness/gotosocial/internal/gtserror"
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"github.com/superseriousbusiness/gotosocial/internal/log"
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)
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const (
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// image magic header bytes.
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magicJPEG = "\xff\xd8\xff"
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)
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// probe will first attempt to probe the file at path using native Go code
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// (for performance), but falls back to using ffprobe to retrieve media details.
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func probe(ctx context.Context, filepath string) (*result, error) {
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// Open input file at given path.
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file, err := os.Open(filepath)
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if err != nil {
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return nil, gtserror.Newf("error opening file %s: %w", filepath, err)
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}
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// Close on return.
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defer file.Close()
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// Byte buf to check for
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// file header magic bytes.
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buf := make([]byte, 3)
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// Read file header into buffer.
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_, err = io.ReadFull(file, buf)
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if err != nil {
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return nil, gtserror.Newf("error reading file %s: %w", filepath, err)
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}
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switch {
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// Attempt to probe JPEG types
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// separately, to save calls into
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// WebAssembly for a common image.
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case string(buf[:len(magicJPEG)]) == magicJPEG:
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log.Debug(ctx, "probing jpeg")
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return probeJPEG(file)
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default:
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// Close BEFORE
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// pass to ffprobe.
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_ = file.Close()
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// For everything else, fall back
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// to calling ffprobe on input file.
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log.Debug(ctx, "ffprobing file")
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return ffprobe(ctx, filepath)
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}
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}
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// probeJPEG decodes the given file as JPEG and determines
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// image details from the decoded JPEG using native Go code.
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func probeJPEG(file *os.File) (*result, error) {
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// Attempt to decode JPEG, adding back hdr magic.
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cfg, err := jpeg.DecodeConfig(io.MultiReader(
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strings.NewReader(magicJPEG),
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file,
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))
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if err != nil {
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return nil, gtserror.Newf("error decoding file %s: %w", file.Name(), err)
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}
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// Jump back to file start.
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_, err = file.Seek(0, 0)
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if err != nil {
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return nil, gtserror.Newf("error seeking in file %s: %w", file.Name(), err)
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}
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// Read orientation data from EXIF.
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orientation := readOrientation(file)
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// Setup result as if
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// ffprobe'd resulting in
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// JPEG file container.
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var res result
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res.format = "image2"
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// Set image orientation data.
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res.orientation = orientation
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// Extract image details.
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res.video = []videoStream{{
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stream: stream{codec: "mjpeg"},
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width: cfg.Width,
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height: cfg.Height,
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// setting a pixel color format
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// doesn't matter for JPEG, as we
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// don't bother even using it.
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pixfmt: "",
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}}
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return &res, nil
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}
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// readOrientation reads orientation EXIF
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// data (if it even exists) from image file.
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//
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// copied from github.com/disintegration/imaging
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// but modified to optimize discard operations.
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func readOrientation(r *os.File) int {
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const (
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markerAPP1 = 0xffe1
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exifHeader = 0x45786966
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byteOrderBE = 0x4d4d
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byteOrderLE = 0x4949
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orientationTag = 0x0112
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)
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// Setup a discard read buffer.
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buf := new(byteutil.Buffer)
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buf.Guarantee(32)
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// discard simply reads into buf.
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discard := func(n int) error {
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buf.Guarantee(n) // ensure big enough
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_, err := io.ReadFull(r, buf.B[:n])
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return err
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}
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// Skip past JPEG SOI marker.
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if err := discard(2); err != nil {
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return orientationUnspecified
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}
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// Find JPEG
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// APP1 marker.
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for {
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var marker, size uint16
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if err := binary.Read(r, binary.BigEndian, &marker); err != nil {
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return orientationUnspecified
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}
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if err := binary.Read(r, binary.BigEndian, &size); err != nil {
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return orientationUnspecified
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}
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if marker>>8 != 0xff {
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return orientationUnspecified // Invalid JPEG marker.
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}
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if marker == markerAPP1 {
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break
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}
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if size < 2 {
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return orientationUnspecified // Invalid block size.
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}
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if err := discard(int(size - 2)); err != nil {
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return orientationUnspecified
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}
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}
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// Check if EXIF
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// header is present.
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var header uint32
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if err := binary.Read(r, binary.BigEndian, &header); err != nil {
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return orientationUnspecified
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}
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if header != exifHeader {
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return orientationUnspecified
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}
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if err := discard(2); err != nil {
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return orientationUnspecified
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}
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// Read byte
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// order info.
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var (
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byteOrderTag uint16
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byteOrder binary.ByteOrder
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)
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if err := binary.Read(r, binary.BigEndian, &byteOrderTag); err != nil {
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return orientationUnspecified
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}
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switch byteOrderTag {
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case byteOrderBE:
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byteOrder = binary.BigEndian
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case byteOrderLE:
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byteOrder = binary.LittleEndian
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default:
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return orientationUnspecified // Invalid byte order flag.
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}
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if err := discard(2); err != nil {
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return orientationUnspecified
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}
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// Skip the
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// EXIF offset.
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var offset uint32
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if err := binary.Read(r, byteOrder, &offset); err != nil {
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return orientationUnspecified
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}
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if offset < 8 {
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return orientationUnspecified // Invalid offset value.
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}
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if err := discard(int(offset - 8)); err != nil {
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return orientationUnspecified
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}
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// Read the
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// number of tags.
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var numTags uint16
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if err := binary.Read(r, byteOrder, &numTags); err != nil {
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return orientationUnspecified
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}
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// Find the orientation tag.
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for i := 0; i < int(numTags); i++ {
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var tag uint16
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if err := binary.Read(r, byteOrder, &tag); err != nil {
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return orientationUnspecified
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}
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if tag != orientationTag {
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if err := discard(10); err != nil {
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return orientationUnspecified
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}
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continue
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}
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if err := discard(6); err != nil {
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return orientationUnspecified
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}
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var val uint16
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if err := binary.Read(r, byteOrder, &val); err != nil {
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return orientationUnspecified
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}
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if val < 1 || val > 8 {
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return orientationUnspecified // Invalid tag value.
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}
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return int(val)
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}
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// Missing orientation tag.
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return orientationUnspecified
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}
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