Avoid calling testing function in creation closure since the context may no longer be valid. Signed-off-by: Derek McGowan <derek@mcgstyle.net>
		
			
				
	
	
		
			57 lines
		
	
	
		
			1.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			57 lines
		
	
	
		
			1.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// +build linux
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package testutil
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import (
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	"io/ioutil"
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	"os"
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	"os/exec"
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	"strings"
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	"github.com/pkg/errors"
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	"github.com/sirupsen/logrus"
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)
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// NewLoopback creates a loopback device, and returns its device name (/dev/loopX), and its clean-up function.
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func NewLoopback(size int64) (string, func() error, error) {
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	// create temporary file for the disk image
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	file, err := ioutil.TempFile("", "containerd-test-loopback")
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	if err != nil {
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		return "", nil, errors.Wrap(err, "could not create temporary file for loopback")
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	}
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	if err := file.Truncate(size); err != nil {
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		return "", nil, errors.Wrap(err, "failed to resize temp file")
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	}
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	file.Close()
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	// create device
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	losetup := exec.Command("losetup", "--find", "--show", file.Name())
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	p, err := losetup.Output()
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	if err != nil {
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		return "", nil, errors.Wrap(err, "loopback setup failed")
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	}
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	deviceName := strings.TrimSpace(string(p))
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	logrus.Debugf("Created loop device %s (using %s)", deviceName, file.Name())
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	cleanup := func() error {
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		// detach device
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		logrus.Debugf("Removing loop device %s", deviceName)
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		losetup := exec.Command("losetup", "--detach", deviceName)
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		err := losetup.Run()
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		if err != nil {
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			return errors.Wrapf(err, "Could not remove loop device %s", deviceName)
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		}
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		// remove file
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		logrus.Debugf("Removing temporary file %s", file.Name())
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		if err = os.Remove(file.Name()); err != nil {
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			return err
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		}
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		return nil
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	}
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	return deviceName, cleanup, nil
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}
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