dropbox: add--dropbox-skip-shared-folders and --dropbox-skip-unowned-folders

This adds two new Dropbox backend flags:

--dropbox-skip-shared-folders skips all shared folder mount points
regardless of ownership.

--dropbox-skip-unowned-folders only skips shared folders that are
not owned by the current user.

These help avoid backing up the same shared folder multiple times when
backing up multiple Dropbox accounts.

Fixes #9514

backend/dropbox/dropbox.go

@@ -267,6 +267,36 @@ See also --dropbox-root-namespace for an alternative way to work with shared
 folders.`,
 			Default:  false,
 			Advanced: true,
+		}, {
+			Name: "skip_shared_folders",
+			Help: `Instructs rclone to skip all shared folders.
+
+When set, any folder that is a shared folder mount point will be
+excluded from directory listings, regardless of ownership.
+This is useful if you prefer to back up shared folders separately
+using a separate remote configured with the shared folder namespace.`,
+			Default:  false,
+			Advanced: true,
+		}, {
+			Name: "skip_unowned_folders",
+			Help: `Instructs rclone to skip shared folders not owned by the current user.
+
+When set, any folder that is a shared folder mount point and not
+owned by the current user will be excluded from directory listings.
+This is useful when backing up multiple Dropbox accounts that share
+common folders, to avoid duplicating the shared data across accounts.
+
+Note: In Dropbox Business, 'Team Folders' are owned by the Team.
+For standard team members, these folders evaluate as 'unowned'
+(editor/viewer access) and will be excluded by this flag. To back up
+Team Folders, do not use this flag or run the backup using a Team Admin
+account.
+
+If --dropbox-skip-shared-folders is also enabled, this flag has no effect.
+
+This makes an extra API call per shared folder mount point.`,
+			Default:  false,
+			Advanced: true,
 		}, {
 			Name:     "pacer_min_sleep",
 			Default:  defaultMinSleep,
@@ -331,21 +361,23 @@ will fail to download them.
 
 // Options defines the configuration for this backend
 type Options struct {
-	ChunkSize        fs.SizeSuffix        `config:"chunk_size"`
-	Impersonate      string               `config:"impersonate"`
-	ImpersonateAdmin string               `config:"impersonate_admin"`
-	SharedFiles      bool                 `config:"shared_files"`
-	SharedFolders    bool                 `config:"shared_folders"`
-	BatchMode        string               `config:"batch_mode"`
-	BatchSize        int                  `config:"batch_size"`
-	BatchTimeout     fs.Duration          `config:"batch_timeout"`
-	AsyncBatch       bool                 `config:"async_batch"`
-	PacerMinSleep    fs.Duration          `config:"pacer_min_sleep"`
-	Enc              encoder.MultiEncoder `config:"encoding"`
-	RootNsid         string               `config:"root_namespace"`
-	ExportFormats    fs.CommaSepList      `config:"export_formats"`
-	SkipExports      bool                 `config:"skip_exports"`
-	ShowAllExports   bool                 `config:"show_all_exports"`
+	ChunkSize          fs.SizeSuffix        `config:"chunk_size"`
+	Impersonate        string               `config:"impersonate"`
+	ImpersonateAdmin   string               `config:"impersonate_admin"`
+	SharedFiles        bool                 `config:"shared_files"`
+	SharedFolders      bool                 `config:"shared_folders"`
+	SkipSharedFolders  bool                 `config:"skip_shared_folders"`
+	SkipUnownedFolders bool                 `config:"skip_unowned_folders"`
+	BatchMode          string               `config:"batch_mode"`
+	BatchSize          int                  `config:"batch_size"`
+	BatchTimeout       fs.Duration          `config:"batch_timeout"`
+	AsyncBatch         bool                 `config:"async_batch"`
+	PacerMinSleep      fs.Duration          `config:"pacer_min_sleep"`
+	Enc                encoder.MultiEncoder `config:"encoding"`
+	RootNsid           string               `config:"root_namespace"`
+	ExportFormats      fs.CommaSepList      `config:"export_formats"`
+	SkipExports        bool                 `config:"skip_exports"`
+	ShowAllExports     bool                 `config:"show_all_exports"`
 }
 
 // Fs represents a remote dropbox server
@@ -1122,6 +1154,26 @@ func (f *Fs) ListP(ctx context.Context, dir string, callback fs.ListRCallback) (
 			leaf := f.opt.Enc.ToStandardName(path.Base(entryPath))
 			remote := path.Join(dir, leaf)
 			if folderInfo != nil {
+				if folderInfo.SharingInfo != nil && folderInfo.SharingInfo.SharedFolderId != "" {
+					if f.opt.SkipSharedFolders {
+						fs.Debugf(remote, "Skipping shared folder")
+						continue
+					}
+					if f.opt.SkipUnownedFolders {
+						var sfMeta *sharing.SharedFolderMetadata
+						err = f.pacer.Call(func() (bool, error) {
+							var apiErr error
+							sfMeta, apiErr = f.sharing.GetFolderMetadata(sharing.NewGetMetadataArgs(folderInfo.SharingInfo.SharedFolderId))
+							return shouldRetry(ctx, apiErr)
+						})
+						if err != nil {
+							fs.Errorf(remote, "Failed to get shared folder metadata (defaulting to include): %v", err)
+						} else if sfMeta != nil && sfMeta.AccessType != nil && sfMeta.AccessType.Tag != sharing.AccessLevelOwner {
+							fs.Debugf(remote, "Skipping unowned shared folder")
+							continue
+						}
+					}
+				}
 				d := fs.NewDir(remote, time.Time{}).SetID(folderInfo.Id)
 				err = list.Add(d)
 				if err != nil {