Guestfish.go

package exec

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

const (
	guestfishBinary = "guestfish"
)

// Checks guestfish is available.
func CheckGuestfish() error {
	output, err := exec.Command(guestfishBinary, "--version").Output()
    if err != nil {
        return errors.New(guestfishBinary+" 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 "+guestfishBinary+" version number!")
	}
	cmd := fields[0]
	if cmd != guestfishBinary {
		return errors.New(guestfishBinary+" is required, but not found.")
	}
	return nil
}

// Copies and unarchives a local archive into a directory (vmDir) inside the VM's filesystem.
func CopyToVM(vmDiskFile, tarFile, vmDir string) error {
	cmd := exec.Command(guestfishBinary, "--rw", "-i", "tar-in", "-a", vmDiskFile, tarFile, vmDir)
	stdoutStderr, err := cmd.CombinedOutput()
	if err != nil {
		output := fmt.Sprintf("[%s]", stdoutStderr)
		msg := "Failed writing to \""+vmDir+"\" in qcow ("+vmDiskFile+")"
		log.Error(msg+": "+output)
		return errors.New(msg)
	}
	return nil
}

// Recursively copies a directory in the VM's filesystem (vmDir) into a compressed archive.
func CopyFromVM(vmDiskFile, vmDir, tarFile string) error {
	cmd := exec.Command(guestfishBinary, "--ro", "-i", "tar-out",  "-a", vmDiskFile, vmDir, tarFile, "compress:gzip")
	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
}