diff --git a/seahub/templates/js/templates.html b/seahub/templates/js/templates.html
index 153f08481a..8c4bc78e66 100644
--- a/seahub/templates/js/templates.html
+++ b/seahub/templates/js/templates.html
@@ -622,7 +622,7 @@
                     </tr>
                     <tr id="add-user-folder-perm">
                         <td>
-                            <input name="email" placeholder="{% trans 'Enter emails, or select' %}" class="w100" />
+                            <input type="hidden" name="email" class="w100" />
                         </td>
                         <td>
                             <select name="permission" class="perm-select w100">
@@ -644,7 +644,7 @@
                     </tr>
                     <tr id="add-group-folder-perm">
                         <td>
-                            <select name="group" placeholder="{% trans 'Select' %}" class="w100" multiple="multiple"></select>
+                            <select name="group" class="w100" multiple="multiple"></select>
                         </td>
                         <td>
                             <select name="permission" class="perm-select w100">
diff --git a/seahub/utils/repo.py b/seahub/utils/repo.py
index a509c21bb9..532bdb85b6 100644
--- a/seahub/utils/repo.py
+++ b/seahub/utils/repo.py
@@ -17,63 +17,6 @@ def list_dir_by_path(cmmt, path):
     else:
         return seafile_api.list_dir_by_commit_and_path(cmmt.repo_id, cmmt.id, path)
 
-def check_user_folder_perm_args(from_user, repo_id, path, to_user, perm=None):
-    if not seafile_api.get_repo(repo_id):
-        return {'error': _(u'Library does not exist'), 'status': 400}
-
-    if from_user != seafile_api.get_repo_owner(repo_id):
-        return {'error': _('Permission denied'), 'status': 403}
-
-    if perm is not None:
-        # add or toggle folder perm
-        if perm != 'r' and perm != 'rw':
-            return {'error': _('Invalid folder permission, should be "rw" or "r"'), 'status': 400}
-
-    if not path.startswith('/'):
-        return {'error': _('Path should start with "/"'), 'status': 400}
-
-    if path != '/' and path.endswith('/'):
-        return {'error': _('Path should NOT ends with "/"'), 'status': 400}
-
-    if seafile_api.get_dir_id_by_path(repo_id, path) is None:
-        return {'error': _('Invalid path'), 'status': 400}
-
-    try:
-        user = User.objects.get(email = to_user)
-    except User.DoesNotExist:
-        user = None
-
-    if user is None:
-        return {'error': _('Invalid username, should be a user already registered'), 'status': 400}
-
-    return {'success': True}
-
-def check_group_folder_perm_args(from_user, repo_id, path, group_id, perm = None):
-    if not seafile_api.get_repo(repo_id):
-        return {'error': _(u'Library does not exist.'), 'status': 400}
-
-    if from_user != seafile_api.get_repo_owner(repo_id):
-        return {'error': _('Permission denied'), 'status': 403}
-
-    if perm is not None:
-        # add or toggle folder perm
-        if perm != 'r' and perm != 'rw':
-            return {'error': _('Invalid folder permission, should be "rw" or "r"'), 'status': 400}
-
-    if not path.startswith('/'):
-        return {'error': _('Path should start with "/"'), 'status': 400}
-
-    if path != '/' and path.endswith('/'):
-        return {'error': _('Path should NOT ends with "/"'), 'status': 400}
-
-    if seafile_api.get_dir_id_by_path(repo_id, path) is None:
-        return {'error': _('Invalid path'), 'status': 400}
-
-    if not seaserv.get_group(group_id):
-        return {'error': _('Invalid group'), 'status': 400}
-
-    return {'success': True}
-
 def get_sub_repo_abbrev_origin_path(repo_name, origin_path):
     """Return abbrev path for sub repo based on `repo_name` and `origin_path`.
 
diff --git a/seahub/views/ajax.py b/seahub/views/ajax.py
index f0e2951db5..9551ec01a3 100644
--- a/seahub/views/ajax.py
+++ b/seahub/views/ajax.py
@@ -55,8 +55,7 @@ from seahub.utils import check_filename_with_rename, EMPTY_SHA1, \
     get_repo_last_modify, gen_file_upload_url, is_org_context, \
     get_org_user_events, get_user_events, get_file_type_and_ext, \
     is_valid_username, send_perm_audit_msg, get_origin_repo_info, is_pro_version
-from seahub.utils.repo import check_group_folder_perm_args, \
-    check_user_folder_perm_args, get_sub_repo_abbrev_origin_path
+from seahub.utils.repo import get_sub_repo_abbrev_origin_path
 from seahub.utils.star import star_file, unstar_file
 from seahub.base.accounts import User
 from seahub.thumbnail.utils import get_thumbnail_src, allow_generate_thumbnail
@@ -2295,18 +2294,47 @@ def set_user_folder_perm(request, repo_id):
     perm = request.POST.get('perm', None)
     op_type = request.POST.get('type', None)
 
+    username = request.user.username
+
+    ## check params
     if not user or not path or not perm or \
         op_type != 'add' and op_type != 'modify' and op_type != 'delete':
         return HttpResponse(json.dumps({"error": _('Argument missing')}),
                             status=400, content_type=content_type)
 
+    if not seafile_api.get_repo(repo_id):
+        return HttpResponse(json.dumps({"error": _('Library does not exist')}),
+                            status=400, content_type=content_type)
+
+    if username != seafile_api.get_repo_owner(repo_id):
+        return HttpResponse(json.dumps({"error": _('Permission denied')}),
+                            status=403, content_type=content_type)
+
+    if perm is not None:
+        if perm != 'r' and perm != 'rw':
+            return HttpResponse(json.dumps({
+                "error": _('Invalid folder permission, should be "rw" or "r"')
+                }), status=400, content_type=content_type)
+
+    if not path.startswith('/'):
+        return HttpResponse(json.dumps({"error": _('Path should start with "/"')}),
+                            status=400, content_type=content_type)
+
+    if path != '/' and path.endswith('/'):
+        return HttpResponse(json.dumps({"error": _('Path should not end with "/"')}),
+                            status=400, content_type=content_type)
+
+    if seafile_api.get_dir_id_by_path(repo_id, path) is None:
+        return HttpResponse(json.dumps({"error": _('Invalid path')}),
+                            status=400, content_type=content_type)
+
+    ## add perm for user(s)
     if op_type == 'add':
         return add_user_folder_perm(request, repo_id, user, path, perm)
 
-    result = check_user_folder_perm_args(request.user.username, repo_id, path, user, perm)
-    if 'error' in result:
-        return HttpResponse(json.dumps(result), status=result['status'],
-                            content_type=content_type)
+    if not is_registered_user(user):
+        return HttpResponse(json.dumps({"error": _('Invalid user, should be registered')}),
+                            status=400, content_type=content_type)
 
     user_folder_perm = seafile_api.get_folder_user_perm(repo_id, path, user)
 
@@ -2314,8 +2342,7 @@ def set_user_folder_perm(request, repo_id):
         if user_folder_perm and user_folder_perm != perm:
             try:
                 seafile_api.set_folder_user_perm(repo_id, path, perm, user)
-                send_perm_audit_msg('modify-repo-perm', request.user.username,
-                                    user, repo_id, path, perm)
+                send_perm_audit_msg('modify-repo-perm', username, user, repo_id, path, perm)
             except SearpcError as e:
                 logger.error(e)
                 return HttpResponse(json.dumps({"error": _('Operation failed')}),
@@ -2328,8 +2355,7 @@ def set_user_folder_perm(request, repo_id):
         if user_folder_perm:
             try:
                 seafile_api.rm_folder_user_perm(repo_id, path, user)
-                send_perm_audit_msg('delete-repo-perm', request.user.username,
-                                    user, repo_id, path, perm)
+                send_perm_audit_msg('delete-repo-perm', username, user, repo_id, path, perm)
             except SearpcError as e:
                 logger.error(e)
                 return HttpResponse(json.dumps({"error": _('Operation failed')}),
@@ -2349,6 +2375,7 @@ def add_user_folder_perm(request, repo_id, users, path, perm):
     emails = users.split(',')
 
     success, failed = [], []
+    username = request.user.username
 
     for user in [e.strip() for e in emails if e.strip()]:
         if not is_valid_username(user):
@@ -2359,11 +2386,6 @@ def add_user_folder_perm(request, repo_id, users, path, perm):
             failed.append(user)
             continue
 
-        result = check_user_folder_perm_args(request.user.username, repo_id, path, user, perm)
-        if 'error' in result:
-            return HttpResponse(json.dumps(result), status=result['status'],
-                                content_type=content_type)
-
         user_folder_perm = seafile_api.get_folder_user_perm(repo_id, path, user)
 
         if user_folder_perm:
@@ -2372,8 +2394,7 @@ def add_user_folder_perm(request, repo_id, users, path, perm):
 
         try:
             seafile_api.add_folder_user_perm(repo_id, path, perm, user)
-            send_perm_audit_msg('add-repo-perm', request.user.username,
-                                user, repo_id, path, perm)
+            send_perm_audit_msg('add-repo-perm', username, user, repo_id, path, perm)
             success.append({
                 'user': user,
                 'user_name': email2nickname(user)
@@ -2386,7 +2407,9 @@ def add_user_folder_perm(request, repo_id, users, path, perm):
         data = json.dumps({"success": success, "failed": failed})
         return HttpResponse(data, content_type=content_type)
     else:
-        data = json.dumps({"error": _("Please check the email(s) you entered")})
+        data = json.dumps({
+            "error": _("Please check the email(s) you entered and the contacts you selected")
+            })
         return HttpResponse(data, status=400, content_type=content_type)
 
 @login_required_ajax
@@ -2408,19 +2431,48 @@ def set_group_folder_perm(request, repo_id):
     perm = request.POST.get('perm', None)
     op_type = request.POST.get('type', None)
 
+    username = request.user.username
+
     if not group_id or not path or not perm or \
         op_type != 'add' and op_type != 'modify' and op_type != 'delete':
         return HttpResponse(json.dumps({"error": _('Argument missing')}),
                             status=400, content_type=content_type)
 
+    ## check params
+    if not seafile_api.get_repo(repo_id):
+        return HttpResponse(json.dumps({"error": _('Library does not exist')}),
+                            status=400, content_type=content_type)
+
+    if username != seafile_api.get_repo_owner(repo_id):
+        return HttpResponse(json.dumps({"error": _('Permission denied')}),
+                            status=403, content_type=content_type)
+
+    if perm is not None:
+        if perm != 'r' and perm != 'rw':
+            return HttpResponse(json.dumps({
+                "error": _('Invalid folder permission, should be "rw" or "r"')
+                }), status=400, content_type=content_type)
+
+    if not path.startswith('/'):
+        return HttpResponse(json.dumps({"error": _('Path should start with "/"')}),
+                            status=400, content_type=content_type)
+
+    if path != '/' and path.endswith('/'):
+        return HttpResponse(json.dumps({"error": _('Path should not end with "/"')}),
+                            status=400, content_type=content_type)
+
+    if seafile_api.get_dir_id_by_path(repo_id, path) is None:
+        return HttpResponse(json.dumps({"error": _('Invalid path')}),
+                            status=400, content_type=content_type)
+
+    ## add perm for group(s)
     if op_type == 'add':
         return add_group_folder_perm(request, repo_id, group_id, path, perm)
 
     group_id = int(group_id)
-    result = check_group_folder_perm_args(request.user.username, repo_id, path, group_id, perm)
-    if 'error' in result:
-        return HttpResponse(json.dumps(result), status=result['status'],
-                            content_type=content_type)
+    if not seaserv.get_group(group_id):
+        return HttpResponse(json.dumps({"error": _('Invalid group')}),
+                            status=400, content_type=content_type)
 
     group_folder_perm = seafile_api.get_folder_group_perm(repo_id, path, group_id)
 
@@ -2428,8 +2480,7 @@ def set_group_folder_perm(request, repo_id):
         if group_folder_perm and group_folder_perm != perm:
             try:
                 seafile_api.set_folder_group_perm(repo_id, path, perm, group_id)
-                send_perm_audit_msg('modify-repo-perm', request.user.username,
-                                    group_id, repo_id, path, perm)
+                send_perm_audit_msg('modify-repo-perm', username, group_id, repo_id, path, perm)
             except SearpcError as e:
                 logger.error(e)
                 return HttpResponse(json.dumps({"error": _('Operation failed')}),
@@ -2442,8 +2493,7 @@ def set_group_folder_perm(request, repo_id):
         if group_folder_perm:
             try:
                 seafile_api.rm_folder_group_perm(repo_id, path, group_id)
-                send_perm_audit_msg('delete-repo-perm', request.user.username,
-                                    group_id, repo_id, path, perm)
+                send_perm_audit_msg('delete-repo-perm', username, group_id, repo_id, path, perm)
             except SearpcError as e:
                 logger.error(e)
                 return HttpResponse(json.dumps({"error": _('Operation failed')}),
@@ -2467,10 +2517,8 @@ def add_group_folder_perm(request, repo_id, group_ids, path, perm):
 
     for group_id in group_id_list:
         group_id = int(group_id)
-        result = check_group_folder_perm_args(username, repo_id, path, group_id, perm)
-        if 'error' in result:
-            return HttpResponse(json.dumps(result), status=result['status'],
-                                content_type=content_type)
+        if not seaserv.get_group(group_id):
+            failed.append(group_id)
 
         group_folder_perm = seafile_api.get_folder_group_perm(repo_id, path, group_id)
 
@@ -2480,8 +2528,7 @@ def add_group_folder_perm(request, repo_id, group_ids, path, perm):
 
         try:
             seafile_api.add_folder_group_perm(repo_id, path, perm, group_id)
-            send_perm_audit_msg('add-repo-perm', request.user.username,
-                                group_id, repo_id, path, perm)
+            send_perm_audit_msg('add-repo-perm', username, group_id, repo_id, path, perm)
             success.append({
                 'group_id': group_id,
                 "group_name": get_group(group_id).group_name,
@@ -2494,8 +2541,8 @@ def add_group_folder_perm(request, repo_id, group_ids, path, perm):
         data = json.dumps({"success": success, "failed": failed})
         return HttpResponse(data, content_type=content_type)
     else:
-        data = json.dumps({"error": _("Internal server error")})
-        return HttpResponse(data, status=500, content_type=content_type)
+        data = json.dumps({"error": _("Failed")})
+        return HttpResponse(data, status=400, content_type=content_type)
 
 @login_required_ajax
 def get_group_basic_info(request, group_id):
diff --git a/static/scripts/app/views/folder-perm.js b/static/scripts/app/views/folder-perm.js
index 7f84e6d381..712acad6b0 100644
--- a/static/scripts/app/views/folder-perm.js
+++ b/static/scripts/app/views/folder-perm.js
@@ -19,11 +19,7 @@ define([
             this.repo_id = options.repo_id;
             this.obj_name = options.obj_name;
             this.dir_path = options.dir_path;
-            if (this.dir_path === '/') {
-                this.path = this.dir_path + this.obj_name;
-            } else {
-                this.path = this.dir_path + '/' + this.obj_name;
-            }
+            this.path = Common.pathJoin([this.dir_path, this.obj_name])
 
             this.render();
 
@@ -94,6 +90,7 @@ define([
 
             // use select2 to 'user' input in 'add user perm'
             $('[name="email"]', $add_user_perm).select2({
+                placeholder: gettext("Enter emails or select contacts"),
                 tags: function () {
                     var contacts = app.pageOptions.contacts || [];
                     var contact_list = [];
@@ -128,6 +125,7 @@ define([
                 g_opts += '<option value="' + groups[i].id + '" data-index="' + i + '">' + groups[i].name + '</option>';
             }
             $('[name="group"]', $add_group_perm).html(g_opts).select2({
+                placeholder: gettext("Select groups"),
                 escapeMarkup: function(m) { return m; }
             });
         },
diff --git a/static/scripts/app/views/share.js b/static/scripts/app/views/share.js
index 6bdc8a66c1..fa8efd06be 100644
--- a/static/scripts/app/views/share.js
+++ b/static/scripts/app/views/share.js
@@ -410,7 +410,7 @@ define([
             loading_tip.show();
 
             $('[name="emails"]', form).select2({
-                placeholder: gettext("Select contacts or input"),
+                placeholder: gettext("Enter emails or select contacts"),
                 width: '400px',
                 // with 'tags', the user can directly enter, not just select
                 // tags need `<input type="hidden" />`, not `<select>`