data_layer.go

Documentation: github.com/dsoprea/go-exif/v3

     1  package exif
     2  
     3  import (
     4  	"io"
     5  
     6  	"github.com/dsoprea/go-logging"
     7  	"github.com/dsoprea/go-utility/v2/filesystem"
     8  )
     9  
    10  type ExifBlobSeeker interface {
    11  	GetReadSeeker(initialOffset int64) (rs io.ReadSeeker, err error)
    12  }
    13  
    14  // ExifReadSeeker knows how to retrieve data from the EXIF blob relative to the
    15  // beginning of the blob (so, absolute position (0) is the first byte of the
    16  // EXIF data).
    17  type ExifReadSeeker struct {
    18  	rs io.ReadSeeker
    19  }
    20  
    21  func NewExifReadSeeker(rs io.ReadSeeker) *ExifReadSeeker {
    22  	return &ExifReadSeeker{
    23  		rs: rs,
    24  	}
    25  }
    26  
    27  func NewExifReadSeekerWithBytes(exifData []byte) *ExifReadSeeker {
    28  	sb := rifs.NewSeekableBufferWithBytes(exifData)
    29  	edbs := NewExifReadSeeker(sb)
    30  
    31  	return edbs
    32  }
    33  
    34  // Fork creates a new ReadSeeker instead that wraps a BouncebackReader to
    35  // maintain its own position in the stream.
    36  func (edbs *ExifReadSeeker) GetReadSeeker(initialOffset int64) (rs io.ReadSeeker, err error) {
    37  	defer func() {
    38  		if state := recover(); state != nil {
    39  			err = log.Wrap(state.(error))
    40  		}
    41  	}()
    42  
    43  	br, err := rifs.NewBouncebackReader(edbs.rs)
    44  	log.PanicIf(err)
    45  
    46  	_, err = br.Seek(initialOffset, io.SeekStart)
    47  	log.PanicIf(err)
    48  
    49  	return br, nil
    50  }
    51
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