VirtTarOut.go

package exec

import (
	"fmt"
	"os/exec"
	"strings"
	"errors"
)

const (
	virtTarOutBinary = "virt-tar-out"
)

// Checks virt-tar-out is available.
func CheckVirtCopyOut() error {
	output, err := exec.Command(virtTarOutBinary, "--version").Output()
    if err != nil {
        return errors.New(virtTarOutBinary+" is required but not found. On Ubuntu/Debian, it can be installed with \"sudo apt-get install guestfish\".")
	}
	out := string(output)
	lines := strings.Split(out, "\n")
	fields := strings.Split(lines[0], " ")
	if len(fields) < 2 {
		return errors.New("Failed extracting "+virtTarOutBinary+" version number!")
	}
	cmd := fields[0]
	if cmd != virtTarOutBinary {
		return errors.New(virtTarOutBinary+" is required, but not found.")
	}
	return nil
}

// Runs virt-tar-in which unarchive a local archive into a directory (vmDir) inside the VM disk.

// Runs virt-copy-out which recursively extract a directory from the VM's
// filesystem (vmDir) into a tar archive.
func CopyFromVM(vmDiskFile, vmDir, tarFile string) error {
	cmd := exec.Command(virtTarOutBinary, "-a", vmDiskFile, vmDir, tarFile)
	stdoutStderr, err := cmd.CombinedOutput()
	if err != nil {
		output := fmt.Sprintf("[%s]", stdoutStderr)
		msg := "Failed reading \""+vmDir+"\" in qcow ("+vmDiskFile+"): "+output
		log.Error(msg)
		return errors.New(msg)
	}
	return nil
}