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writer.go
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/
writer.go
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package layers
import (
"archive/tar"
"crypto/sha256"
"fmt"
"io"
"os"
"runtime"
"github.com/buildpacks/imgutil/layer"
"github.com/buildpacks/lifecycle/archive"
)
type layerWriter struct {
io.Writer
io.Closer
hasher *concurrentHasher
path string
}
func newFileLayerWriter(dest string) (*layerWriter, error) {
hasher := newConcurrentHasher(sha256.New())
file, err := os.Create(dest)
if err != nil {
return nil, err
}
w := io.MultiWriter(hasher, file)
return &layerWriter{w, file, hasher, dest}, nil
}
func (lw *layerWriter) Digest() string {
return fmt.Sprintf("sha256:%x", lw.hasher.Sum(nil))
}
func tarWriter(lw *layerWriter) *archive.NormalizingTarWriter {
var tw *archive.NormalizingTarWriter
if runtime.GOOS == "windows" {
tw = archive.NewNormalizingTarWriter(layer.NewWindowsWriter(lw))
} else {
tw = archive.NewNormalizingTarWriter(tar.NewWriter(lw))
}
tw.WithModTime(archive.NormalizedModTime)
return tw
}