new stuff

src/exec/VirtCopyIn.go

+package exec
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+	"errors"
+)
+
+const (
+	virtcopyinBinary = "virt-copy-in"
+)
+
+// Check virt-copy-in is available.
+func CheckVirtCopyIn() error {
+	output, err := exec.Command(virtcopyinBinary, "--version").Output()
+    if err != nil {
+        return errors.New(virtcopyinBinary+" 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 "+virtcopyinBinary+" version number!")
+	}
+	cmd := fields[0]
+	if cmd != virtcopyinBinary {
+		return errors.New(virtcopyinBinary+" is required, but not found.")
+	}
+	return nil
+}
+
+// Creates a virt-copy-in command that recursively copy a directory on the host (localDir)
+// into a directory on the VM's filesystem (vmDir).
+// Note: both directories must exist, otherwise the command will fail.
+func CopyToVM(vmDiskFile, localDir, vmDir string) error {
+	log.Info("localDir = ",localDir)
+	cmd := exec.Command(virtcopyinBinary, "-a", vmDiskFile, localDir, vmDir)
+	stdoutStderr, err := cmd.CombinedOutput()
+	if err != nil {
+		output := fmt.Sprintf("[%s]", stdoutStderr)
+		msg := "Failed writing to \""+vmDir+"\" in qcow ("+vmDiskFile+"): "+output
+		log.Error(msg)
+		return errors.New(msg)
+	}
+	return nil
+}