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package copy
import (
"fmt"
"hash"
"io"
digest "github.com/opencontainers/go-digest"
)
type digestingReader struct {
source io.Reader
digester digest.Digester
hash hash.Hash
expectedDigest digest.Digest
validationFailed bool
validationSucceeded bool
}
// newDigestingReader returns an io.Reader implementation with contents of source, which will eventually return a non-EOF error
// or set validationSucceeded/validationFailed to true if the source stream does/does not match expectedDigest.
// (neither is set if EOF is never reached).
func newDigestingReader(source io.Reader, expectedDigest digest.Digest) (*digestingReader, error) {
var digester digest.Digester
if err := expectedDigest.Validate(); err != nil {
return nil, fmt.Errorf("Invalid digest specification %s", expectedDigest)
}
digestAlgorithm := expectedDigest.Algorithm()
if !digestAlgorithm.Available() {
return nil, fmt.Errorf("Invalid digest specification %s: unsupported digest algorithm %s", expectedDigest, digestAlgorithm)
}
digester = digestAlgorithm.Digester()
return &digestingReader{
source: source,
digester: digester,
hash: digester.Hash(),
expectedDigest: expectedDigest,
validationFailed: false,
}, nil
}
func (d *digestingReader) Read(p []byte) (int, error) {
n, err := d.source.Read(p)
if n > 0 {
if n2, err := d.hash.Write(p[:n]); n2 != n || err != nil {
// Coverage: This should not happen, the hash.Hash interface requires
// d.digest.Write to never return an error, and the io.Writer interface
// requires n2 == len(input) if no error is returned.
return 0, fmt.Errorf("updating digest during verification: %d vs. %d: %w", n2, n, err)
}
}
if err == io.EOF {
actualDigest := d.digester.Digest()
if actualDigest != d.expectedDigest {
d.validationFailed = true
return 0, fmt.Errorf("Digest did not match, expected %s, got %s", d.expectedDigest, actualDigest)
}
d.validationSucceeded = true
}
return n, err
}
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