github.com/anchore/syft@v1.38.2/syft/format/decoders_collection.go (about)

     1  package format
     2  
     3  import (
     4  	"fmt"
     5  	"io"
     6  
     7  	"github.com/anchore/syft/internal/log"
     8  	"github.com/anchore/syft/syft/format/internal/stream"
     9  	"github.com/anchore/syft/syft/sbom"
    10  )
    11  
    12  var _ sbom.FormatDecoder = (*DecoderCollection)(nil)
    13  
    14  type DecoderCollection struct {
    15  	decoders []sbom.FormatDecoder
    16  }
    17  
    18  func NewDecoderCollection(decoders ...sbom.FormatDecoder) sbom.FormatDecoder {
    19  	return &DecoderCollection{
    20  		decoders: decoders,
    21  	}
    22  }
    23  
    24  // Decode takes a set of bytes and attempts to decode it into an SBOM relative to the decoders in the collection.
    25  func (c *DecoderCollection) Decode(r io.Reader) (*sbom.SBOM, sbom.FormatID, string, error) {
    26  	if r == nil {
    27  		return nil, "", "", fmt.Errorf("no SBOM bytes provided")
    28  	}
    29  
    30  	reader, err := stream.SeekableReader(r)
    31  	if err != nil {
    32  		return nil, "", "", fmt.Errorf("unable to create a seekable reader: %w", err)
    33  	}
    34  
    35  	var bestID sbom.FormatID
    36  	for _, d := range c.decoders {
    37  		_, err = reader.Seek(0, io.SeekStart)
    38  		if err != nil {
    39  			return nil, "", "", fmt.Errorf("unable to seek to start of SBOM: %w", err)
    40  		}
    41  		id, version := d.Identify(reader)
    42  		if id == "" || version == "" {
    43  			if id != "" {
    44  				bestID = id
    45  			}
    46  			continue
    47  		}
    48  
    49  		_, err = reader.Seek(0, io.SeekStart)
    50  		if err != nil {
    51  			return nil, "", "", fmt.Errorf("unable to seek to start of SBOM: %w", err)
    52  		}
    53  		return d.Decode(reader)
    54  	}
    55  
    56  	if bestID != "" {
    57  		return nil, bestID, "", fmt.Errorf("sbom format found to be %q but the version is not supported", bestID)
    58  	}
    59  
    60  	return nil, "", "", fmt.Errorf("sbom format not recognized")
    61  }
    62  
    63  // Identify takes a set of bytes and attempts to identify the format of the SBOM relative to the decoders in the collection.
    64  func (c *DecoderCollection) Identify(r io.Reader) (sbom.FormatID, string) {
    65  	if r == nil {
    66  		return "", ""
    67  	}
    68  
    69  	reader, err := stream.SeekableReader(r)
    70  	if err != nil {
    71  		log.Debugf("unable to create a seekable reader: %v", err)
    72  		return "", ""
    73  	}
    74  
    75  	for _, d := range c.decoders {
    76  		_, err = reader.Seek(0, io.SeekStart)
    77  		if err != nil {
    78  			log.Debugf("unable to seek to start of SBOM: %v", err)
    79  		}
    80  		id, version := d.Identify(reader)
    81  		if id != "" && version != "" {
    82  			return id, version
    83  		}
    84  	}
    85  	return "", ""
    86  }