Read all EXIF tags in file

[vinhphuctadang]

Hi author and contributors,

I am really happy to see that v3 has been released with many support for the way reading EXIF. I made this issue to ask some questions about finding all EXIF data of an image file:

To find all EXIF data, I tried to iterate over all blocks which are likely to have EXIF using the following code:

(ErrInvalidMaxBlock is nothing but my self-defined error)

func GetAllExifData(imageData []byte, so *ScanOptions, maxBlock int) (exifTags []ExifTag, blockRead int, err error) {
	defer func() {
		if state := recover(); state != nil {
			err = log.Wrap(state.(error))
		}
	}()

	if maxBlock < -1 {
		return nil, 0, ErrInvalidMaxBlock
	}

	for n := 0; maxBlock == -1 || n < maxBlock; n++ {
		exifData, err := exif.SearchAndExtractExif(imageData)
		if err != nil {
			if errors.Is(err, exif.ErrNoExif) {
				if n == 0 {
					return exifTags, blockRead, nil
				}
				break
			}
			log.Panic(err)
		}

		// help find next EXIF without searching from start
		imageData = exifData[ExifSignatureLength:]

		entries, _, err := GetFlatExifDataUniversalSearch(exifData, so, true)
		if err != nil {
			if log.Is(err, io.EOF) || log.Is(err, io.ErrUnexpectedEOF) {
				continue
			}
			log.PanicIf(err)
		}

		blockRead++
		exifTags = append(exifTags, entries...)
	}

	return exifTags, blockRead, nil
}

I would like to ask 2 questions:

1. Do I missed anything while brute-forcing for EXIF block? The library offers me SearchAndExtractExifN, but when I want to iterate faster, I think I need to reduce the array size that way.

2. When I GetFlatExifDataUniversalSearch for the block, sometimes I get

TagId=[0x0004] TagName=[GPSLongitude] Value=[[68 0 192 92 276 204 0 0 3 0 8 8 160 65535 0 32 0 0 1 0 0 276 204 84 0 0 248 0 0 65535 65535 0 0 0]]

Have seen one issue that mentioned this wrong entry, but how could I skip this wrong entry?

Hope you all have a nice day!