bisync: support two --backup-dir paths on different remotes

Before this change, bisync supported `--backup-dir` only when `Path1` and
`Path2` were different paths on the same remote. With this change, bisync
introduces new `--backup-dir1` and `--backup-dir2` flags to support separate
backup-dirs for `Path1` and `Path2`.

`--backup-dir1` and `--backup-dir2` can use different remotes from each other,
but `--backup-dir1` must use the same remote as `Path1`, and `--backup-dir2`
must use the same remote as `Path2`. Each backup directory must not overlap its
respective bisync Path without being excluded by a filter rule.

The standard `--backup-dir` will also work, if both paths use the same remote
(but note that deleted files from both paths would be mixed together in the
same dir). If either `--backup-dir1` and `--backup-dir2` are set, they will
override `--backup-dir`.

cmd/bisync/cmd.go

@@ -40,6 +40,9 @@ type Options struct {
 	Force                 bool
 	FiltersFile           string
 	Workdir               string
+	OrigBackupDir         string
+	BackupDir1            string
+	BackupDir2            string
 	DryRun                bool
 	NoCleanup             bool
 	SaveQueues            bool // save extra debugging files (test only flag)
@@ -107,6 +110,8 @@ func init() {
 	Opt.Retries = 3
 	cmd.Root.AddCommand(commandDefinition)
 	cmdFlags := commandDefinition.Flags()
+	// when adding new flags, remember to also update the rc params:
+	// cmd/bisync/rc.go cmd/bisync/help.go (not docs/content/rc.md)
 	flags.BoolVarP(cmdFlags, &Opt.Resync, "resync", "1", Opt.Resync, "Performs the resync run. Path1 files may overwrite Path2 versions. Consider using --verbose or --dry-run first.", "")
 	flags.BoolVarP(cmdFlags, &Opt.CheckAccess, "check-access", "", Opt.CheckAccess, makeHelp("Ensure expected {CHECKFILE} files are found on both Path1 and Path2 filesystems, else abort."), "")
 	flags.StringVarP(cmdFlags, &Opt.CheckFilename, "check-filename", "", Opt.CheckFilename, makeHelp("Filename for --check-access (default: {CHECKFILE})"), "")
@@ -116,6 +121,8 @@ func init() {
 	flags.BoolVarP(cmdFlags, &Opt.RemoveEmptyDirs, "remove-empty-dirs", "", Opt.RemoveEmptyDirs, "Remove ALL empty directories at the final cleanup step.", "")
 	flags.StringVarP(cmdFlags, &Opt.FiltersFile, "filters-file", "", Opt.FiltersFile, "Read filtering patterns from a file", "")
 	flags.StringVarP(cmdFlags, &Opt.Workdir, "workdir", "", Opt.Workdir, makeHelp("Use custom working dir - useful for testing. (default: {WORKDIR})"), "")
+	flags.StringVarP(cmdFlags, &Opt.BackupDir1, "backup-dir1", "", Opt.BackupDir1, "--backup-dir for Path1. Must be a non-overlapping path on the same remote.", "")
+	flags.StringVarP(cmdFlags, &Opt.BackupDir2, "backup-dir2", "", Opt.BackupDir2, "--backup-dir for Path2. Must be a non-overlapping path on the same remote.", "")
 	flags.BoolVarP(cmdFlags, &tzLocal, "localtime", "", tzLocal, "Use local time in listings (default: UTC)", "")
 	flags.BoolVarP(cmdFlags, &Opt.NoCleanup, "no-cleanup", "", Opt.NoCleanup, "Retain working files (useful for troubleshooting and testing).", "")
 	flags.BoolVarP(cmdFlags, &Opt.IgnoreListingChecksum, "ignore-listing-checksum", "", Opt.IgnoreListingChecksum, "Do not use checksums for listings (add --ignore-checksum to additionally skip post-copy checksum checks)", "")

cmd/bisync/deltas.go

@@ -346,6 +346,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 					} else {
 						fs.Debugf(nil, "Files are NOT equal: %s", file)
 						b.indent("!Path1", p1+"..path1", "Renaming Path1 copy")
+						ctxMove = b.setBackupDir(ctxMove, 1) // in case already a file with new name
 						if err = operations.MoveFile(ctxMove, b.fs1, b.fs1, file+"..path1", file); err != nil {
 							err = fmt.Errorf("path1 rename failed for %s: %w", p1, err)
 							b.critical = true
@@ -360,6 +361,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 						copy1to2.Add(file + "..path1")
 
 						b.indent("!Path2", p2+"..path2", "Renaming Path2 copy")
+						ctxMove = b.setBackupDir(ctxMove, 2) // in case already a file with new name
 						if err = operations.MoveFile(ctxMove, b.fs2, b.fs2, alias+"..path2", alias); err != nil {
 							err = fmt.Errorf("path2 rename failed for %s: %w", alias, err)
 							return
@@ -426,6 +428,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 	if copy2to1.NotEmpty() {
 		changes1 = true
 		b.indent("Path2", "Path1", "Do queued copies to")
+		ctx = b.setBackupDir(ctx, 1)
 		results2to1, err = b.fastCopy(ctx, b.fs2, b.fs1, copy2to1, "copy2to1")
 
 		// retries, if any
@@ -442,6 +445,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 	if copy1to2.NotEmpty() {
 		changes2 = true
 		b.indent("Path1", "Path2", "Do queued copies to")
+		ctx = b.setBackupDir(ctx, 2)
 		results1to2, err = b.fastCopy(ctx, b.fs1, b.fs2, copy1to2, "copy1to2")
 
 		// retries, if any

cmd/bisync/help.go

@@ -10,7 +10,7 @@ func makeHelp(help string) string {
 		"|", "`",
 		"{MAXDELETE}", strconv.Itoa(DefaultMaxDelete),
 		"{CHECKFILE}", DefaultCheckFilename,
-		"{WORKDIR}", DefaultWorkdir,
+		// "{WORKDIR}", DefaultWorkdir,
 	)
 	return replacer.Replace(help)
 }
@@ -37,7 +37,9 @@ var rcHelp = makeHelp(`This takes the following parameters
 - ignoreListingChecksum - Do not use checksums for listings
 - resilient - Allow future runs to retry after certain less-serious errors, instead of requiring resync. 
             Use at your own risk!
-- workdir - server directory for history files (default: {WORKDIR})
+- workdir - server directory for history files (default: |~/.cache/rclone/bisync|)
+- backupdir1 - --backup-dir for Path1. Must be a non-overlapping path on the same remote.
+- backupdir2 - --backup-dir for Path2. Must be a non-overlapping path on the same remote.
 - noCleanup - retain working files
 
 See [bisync command help](https://rclone.org/commands/rclone_bisync/)

cmd/bisync/operations.go

@@ -68,6 +68,8 @@ func Bisync(ctx context.Context, fs1, fs2 fs.Fs, optArg *Options) (err error) {
 	if opt.Workdir == "" {
 		opt.Workdir = DefaultWorkdir
 	}
+	ci := fs.GetConfig(ctx)
+	opt.OrigBackupDir = ci.BackupDir
 
 	if !opt.DryRun && !opt.Force {
 		if fs1.Precision() == fs.ModTimeNotSupported {
@@ -358,7 +360,9 @@ func (b *bisyncRun) runLocked(octx context.Context) (err error) {
 	// Optional rmdirs for empty directories
 	if opt.RemoveEmptyDirs {
 		fs.Infof(nil, "Removing empty directories")
+		fctx = b.setBackupDir(fctx, 1)
 		err1 := operations.Rmdirs(fctx, b.fs1, "", true)
+		fctx = b.setBackupDir(fctx, 2)
 		err2 := operations.Rmdirs(fctx, b.fs2, "", true)
 		err := err1
 		if err == nil {
@@ -445,6 +449,8 @@ func (b *bisyncRun) resync(octx, fctx context.Context) error {
 	}
 	ci := fs.GetConfig(ctxSync)
 	ci.IgnoreExisting = true
+	ctxSync = b.setBackupDir(ctxSync, 1)
+	// 2 to 1
 	if results2to1, err = b.resyncDir(ctxSync, b.fs2, b.fs1); err != nil {
 		b.critical = true
 		return err
@@ -452,6 +458,8 @@ func (b *bisyncRun) resync(octx, fctx context.Context) error {
 
 	b.indent("Path1", "Path2", "Resync is copying UNIQUE OR DIFFERING files to")
 	ci.IgnoreExisting = false
+	ctxSync = b.setBackupDir(ctxSync, 2)
+	// 1 to 2
 	if results1to2, err = b.resyncDir(ctxSync, b.fs1, b.fs2); err != nil {
 		b.critical = true
 		return err
@@ -581,3 +589,17 @@ func (b *bisyncRun) handleErr(o interface{}, msg string, err error, critical, re
 		}
 	}
 }
+
+// setBackupDir overrides --backup-dir with path-specific version, if set, in each direction
+func (b *bisyncRun) setBackupDir(ctx context.Context, destPath int) context.Context {
+	ci := fs.GetConfig(ctx)
+	ci.BackupDir = b.opt.OrigBackupDir
+	if destPath == 1 && b.opt.BackupDir1 != "" {
+		ci.BackupDir = b.opt.BackupDir1
+	}
+	if destPath == 2 && b.opt.BackupDir2 != "" {
+		ci.BackupDir = b.opt.BackupDir1
+	}
+	fs.Debugf(ci.BackupDir, "updated backup-dir for Path%d", destPath)
+	return ctx
+}

cmd/bisync/rc.go

@@ -74,6 +74,12 @@ func rcBisync(ctx context.Context, in rc.Params) (out rc.Params, err error) {
 	if opt.Workdir, err = in.GetString("workdir"); rc.NotErrParamNotFound(err) {
 		return
 	}
+	if opt.BackupDir1, err = in.GetString("backupdir1"); rc.NotErrParamNotFound(err) {
+		return
+	}
+	if opt.BackupDir2, err = in.GetString("backupdir2"); rc.NotErrParamNotFound(err) {
+		return
+	}
 
 	checkSync, err := in.GetString("checkSync")
 	if rc.NotErrParamNotFound(err) {