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package streamdigest
import (
"fmt"
"io"
"os"
"github.com/containers/image/v5/internal/putblobdigest"
"github.com/containers/image/v5/internal/tmpdir"
"github.com/containers/image/v5/types"
)
// ComputeBlobInfo streams a blob to a temporary file and populates Digest and Size in inputInfo.
// The temporary file is returned as an io.Reader along with a cleanup function.
// It is the caller's responsibility to call the cleanup function, which closes and removes the temporary file.
// If an error occurs, inputInfo is not modified.
func ComputeBlobInfo(sys *types.SystemContext, stream io.Reader, inputInfo *types.BlobInfo) (io.Reader, func(), error) {
diskBlob, err := tmpdir.CreateBigFileTemp(sys, "stream-blob")
if err != nil {
return nil, nil, fmt.Errorf("creating temporary on-disk layer: %w", err)
}
cleanup := func() {
diskBlob.Close()
os.Remove(diskBlob.Name())
}
digester, stream := putblobdigest.DigestIfCanonicalUnknown(stream, *inputInfo)
written, err := io.Copy(diskBlob, stream)
if err != nil {
cleanup()
return nil, nil, fmt.Errorf("writing to temporary on-disk layer: %w", err)
}
_, err = diskBlob.Seek(0, io.SeekStart)
if err != nil {
cleanup()
return nil, nil, fmt.Errorf("rewinding temporary on-disk layer: %w", err)
}
inputInfo.Digest = digester.Digest()
inputInfo.Size = written
return diskBlob, cleanup, nil
}
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