Merge pull request #415 from amarcu5/master

Add APFS snapshot support

duplicacy/duplicacy_main.go

@@ -1351,7 +1351,7 @@ func main() {
 				},
 				cli.BoolFlag{
 					Name:  "vss",
-					Usage: "enable the Volume Shadow Copy service (Windows only)",
+					Usage: "enable the Volume Shadow Copy service (Windows and macOS using APFS only)",
 				},
 				cli.IntFlag{
 					Name:     "vss-timeout",

src/duplicacy_shadowcopy.go

@@ -3,6 +3,7 @@
 // Commercial use requires per-user licenses available from https://duplicacy.com
 
 // +build !windows
+// +build !darwin
 
 package duplicacy
 

src/duplicacy_shadowcopy_darwin.go

@@ -0,0 +1,170 @@
+//
+// Shadow copy module for Mac OSX using APFS snapshot
+//
+//
+// This module copyright 2018 Adam Marcus (https://github.com/amarcu5)
+// and may be distributed under the same terms as Duplicacy.
+
+package duplicacy
+
+import (
+	"context"
+	"errors"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+)
+
+var snapshotPath string
+var snapshotDate string
+
+// Converts char array to string
+func CharsToString(ca []int8) string {
+
+	len := len(ca)
+	ba := make([]byte, len) 
+
+	for i, v := range ca {
+		ba[i] = byte(v)
+		if ba[i] == 0 {
+			len = i
+			break
+		}
+	}
+
+	return string(ba[:len])
+}
+
+// Get ID of device containing path
+func GetPathDeviceId(path string) (deviceId int32, err error) {
+
+	stat := syscall.Stat_t{}
+
+	err = syscall.Stat(path, &stat)
+	if err != nil {
+		return 0, err
+	}
+
+	return stat.Dev, nil
+}
+
+// Executes shell command with timeout and returns stdout
+func CommandWithTimeout(timeoutInSeconds int, name string, arg ...string) (output string, err error) {
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeoutInSeconds) * time.Second)
+	defer cancel() 
+
+	cmd := exec.CommandContext(ctx, name, arg...)
+	out, err := cmd.Output()
+
+	if ctx.Err() == context.DeadlineExceeded {
+		err = errors.New("Command '" + name + "' timed out")
+	}
+
+	output = string(out)
+	return output, err
+}
+
+func DeleteShadowCopy() {
+
+	if snapshotPath == "" {
+		return
+	}
+
+	err := exec.Command("/sbin/umount", "-f", snapshotPath).Run()
+	if err != nil {
+		LOG_ERROR("VSS_DELETE", "Error while unmounting snapshot")
+		return
+	}
+
+	err = exec.Command("tmutil", "deletelocalsnapshots", snapshotDate).Run()
+	if err != nil {
+		LOG_ERROR("VSS_DELETE", "Error while deleting local snapshot")
+		return
+	}
+
+	err = os.RemoveAll(snapshotPath)
+	if err != nil {
+		LOG_ERROR("VSS_DELETE", "Error while deleting temporary mount directory")
+		return
+	}
+	
+	LOG_INFO("VSS_DELETE", "Shadow copy unmounted and deleted at %s", snapshotPath)
+
+	snapshotPath = "" 
+}
+
+func CreateShadowCopy(top string, shadowCopy bool, timeoutInSeconds int) (shadowTop string) {
+
+	if !shadowCopy {
+		return top
+	}
+
+	// Check repository filesystem is APFS
+	stat := syscall.Statfs_t{}
+	err := syscall.Statfs(top, &stat)
+	if err != nil {
+		LOG_ERROR("VSS_INIT", "Unable to determine filesystem of repository path")
+		return top
+	}
+	if CharsToString(stat.Fstypename[:]) != "apfs" {
+		LOG_WARN("VSS_INIT", "VSS requires APFS filesystem")
+		return top
+	}
+
+	// Check path is local as tmutil snapshots will not support APFS formatted external drives
+	deviceIdLocal, err := GetPathDeviceId("/")
+	if err != nil {
+		LOG_ERROR("VSS_INIT", "Unable to get device ID of path: /")
+		return top
+	}
+	deviceIdRepository, err := GetPathDeviceId(top)
+	if err != nil {
+		LOG_ERROR("VSS_INIT", "Unable to get device ID of path: ", top)
+		return top
+	}
+	if deviceIdLocal != deviceIdRepository {
+		LOG_WARN("VSS_PATH", "VSS not supported for non-local repository path: ", top)
+		return top 
+	}
+
+	if timeoutInSeconds <= 60 {
+		timeoutInSeconds = 60
+	}
+
+	// Create mount point
+	snapshotPath, err = ioutil.TempDir("/tmp/", "snp_")
+	if err != nil {
+		LOG_ERROR("VSS_CREATE", "Failed to create temporary mount directory")
+		return top
+	}
+
+	// Use tmutil to create snapshot
+	tmutilOutput, err := CommandWithTimeout(timeoutInSeconds, "tmutil", "snapshot")
+	if err != nil {
+		LOG_ERROR("VSS_CREATE", "Error while calling tmutil: ", err)
+		return top
+	}
+
+	colonPos := strings.IndexByte(tmutilOutput, ':')
+	if colonPos < 0 {
+		LOG_ERROR("VSS_CREATE", "Snapshot creation failed: ", tmutilOutput)
+		return top
+	}
+	snapshotDate = strings.TrimSpace(tmutilOutput[colonPos+1:])
+
+	// Mount snapshot as readonly and hide from GUI i.e. Finder
+	_, err = CommandWithTimeout(timeoutInSeconds, 
+		"/sbin/mount", "-t", "apfs", "-o", "nobrowse,-r,-s=com.apple.TimeMachine." + snapshotDate, "/", snapshotPath)
+	if err != nil {
+		LOG_ERROR("VSS_CREATE", "Error while mounting snapshot: ", err)
+		return top
+	}
+
+	LOG_INFO("VSS_DONE", "Shadow copy created and mounted at %s", snapshotPath)
+
+	return snapshotPath + top
+}