96 lines
2.1 KiB
Go
96 lines
2.1 KiB
Go
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package testutil
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import (
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"archive/tar"
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"bytes"
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"crypto/rand"
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"fmt"
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"io"
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"io/ioutil"
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mrand "math/rand"
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"time"
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"github.com/docker/docker/pkg/tarsum"
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)
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// CreateRandomTarFile creates a random tarfile, returning it as an
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// io.ReadSeeker along with its tarsum. An error is returned if there is a
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// problem generating valid content.
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func CreateRandomTarFile() (rs io.ReadSeeker, tarSum string, err error) {
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nFiles := mrand.Intn(10) + 10
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target := &bytes.Buffer{}
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wr := tar.NewWriter(target)
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// Perturb this on each iteration of the loop below.
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header := &tar.Header{
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Mode: 0644,
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ModTime: time.Now(),
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Typeflag: tar.TypeReg,
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Uname: "randocalrissian",
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Gname: "cloudcity",
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AccessTime: time.Now(),
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ChangeTime: time.Now(),
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}
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for fileNumber := 0; fileNumber < nFiles; fileNumber++ {
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fileSize := mrand.Int63n(1<<20) + 1<<20
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header.Name = fmt.Sprint(fileNumber)
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header.Size = fileSize
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if err := wr.WriteHeader(header); err != nil {
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return nil, "", err
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}
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randomData := make([]byte, fileSize)
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// Fill up the buffer with some random data.
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n, err := rand.Read(randomData)
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if n != len(randomData) {
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return nil, "", fmt.Errorf("short read creating random reader: %v bytes != %v bytes", n, len(randomData))
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}
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if err != nil {
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return nil, "", err
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}
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nn, err := io.Copy(wr, bytes.NewReader(randomData))
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if nn != fileSize {
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return nil, "", fmt.Errorf("short copy writing random file to tar")
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}
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if err != nil {
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return nil, "", err
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}
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if err := wr.Flush(); err != nil {
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return nil, "", err
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}
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}
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if err := wr.Close(); err != nil {
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return nil, "", err
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}
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reader := bytes.NewReader(target.Bytes())
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// A tar builder that supports tarsum inline calculation would be awesome
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// here.
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ts, err := tarsum.NewTarSum(reader, true, tarsum.Version1)
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if err != nil {
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return nil, "", err
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}
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nn, err := io.Copy(ioutil.Discard, ts)
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if nn != int64(len(target.Bytes())) {
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return nil, "", fmt.Errorf("short copy when getting tarsum of random layer: %v != %v", nn, len(target.Bytes()))
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}
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if err != nil {
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return nil, "", err
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}
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return bytes.NewReader(target.Bytes()), ts.Sum(nil), nil
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}
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