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// +build linux
package testutil
import (
"io/ioutil"
"os"
"os/exec"
"strings"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// NewLoopback creates a loopback device, and returns its device name (/dev/loopX), and its clean-up function.
func NewLoopback(size int64) (string, func() error, error) {
// create temporary file for the disk image
file, err := ioutil.TempFile("", "containerd-test-loopback")
if err != nil {
return "", nil, errors.Wrap(err, "could not create temporary file for loopback")
}
if err := file.Truncate(size); err != nil {
return "", nil, errors.Wrap(err, "failed to resize temp file")
}
file.Close()
// create device
losetup := exec.Command("losetup", "--find", "--show", file.Name())
p, err := losetup.Output()
if err != nil {
return "", nil, errors.Wrap(err, "loopback setup failed")
}
deviceName := strings.TrimSpace(string(p))
logrus.Debugf("Created loop device %s (using %s)", deviceName, file.Name())
cleanup := func() error {
// detach device
logrus.Debugf("Removing loop device %s", deviceName)
losetup := exec.Command("losetup", "--detach", deviceName)
err := losetup.Run()
if err != nil {
return errors.Wrapf(err, "Could not remove loop device %s", deviceName)
}
// remove file
logrus.Debugf("Removing temporary file %s", file.Name())
return os.Remove(file.Name())
}
return deviceName, cleanup, nil
}
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