Backups: do not hardcode uploaded backup file path

And use a decorator instead of a middleware to delete backup files.

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/backups/__init__.py

@@ -44,7 +44,7 @@ service = None
 MANIFESTS_FOLDER = '/var/lib/plinth/backups-manifests/'
 REPOSITORY = '/var/lib/freedombox/borgbackup'
 # session variable name that stores when a backup file should be deleted
-SESSION_BACKUP_VARIABLE = 'fbx-backup-filestamp'
+SESSION_BACKUP_PATH = 'fbx-backup-path'
 
 
 def init():
@@ -106,11 +106,6 @@ def delete_archive(name):
     actions.superuser_run('backups', ['delete', '--name', name])
 
 
-def delete_upload_backup_file(path):
-    if os.path.isfile(path):
-        os.remove(path)
-
-
 def export_archive(name, filepath):
     """Export an archive as .tar.gz file
 
@@ -156,10 +151,10 @@ def _restore_archive_handler(packet):
                 packet.label, '--destination', '/'], input=locations_data.encode())
 
 
-def restore_from_upload(apps=None):
+def restore_from_upload(path, apps=None):
     """Restore files from (uploaded) eported backup file"""
     api.restore_apps(_restore_exported_archive_handler, app_names=apps,
-                     create_subvolume=False, backup_file=UPLOAD_BACKUP_PATH)
+                     create_subvolume=False, backup_file=path)
 
 
 def restore(archive_path, apps=None):

plinth/modules/backups/decorators.py

@@ -0,0 +1,40 @@
+#
+# This file is part of FreedomBox.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+"""
+Decorators for the backup views.
+"""
+
+import os
+
+from . import SESSION_BACKUP_PATH
+
+
+def delete_tmp_backup_file(function):
+    """Decorator to delete uploaded backup files"""
+
+    def wrap(request, *args, **kwargs):
+        path = request.session.get(SESSION_BACKUP_PATH, None)
+        if path: 
+            if os.path.isfile(path):
+                os.remove(path)
+            del request.session[SESSION_BACKUP_PATH]
+        return function(request, *args, **kwargs)
+
+    wrap.__doc__ = function.__doc__
+    wrap.__name__ = function.__name__
+
+    return wrap

plinth/modules/backups/views.py

@@ -18,12 +18,12 @@
 Views for the backups app.
 """
 
-import gzip
-import mimetypes
 from datetime import datetime
-import os
+import gzip
 from io import BytesIO
-import time
+import mimetypes
+import os
+import tempfile
 from urllib.parse import unquote
 
 from django.contrib import messages
@@ -31,6 +31,7 @@ from django.contrib.messages.views import SuccessMessageMixin
 from django.http import Http404, FileResponse, StreamingHttpResponse
 from django.shortcuts import redirect
 from django.urls import reverse_lazy
+from django.utils.decorators import method_decorator
 from django.utils.translation import ugettext as _
 from django.utils.translation import ugettext_lazy
 from django.views.generic import View, FormView, TemplateView
@@ -38,10 +39,8 @@ from django.views.generic import View, FormView, TemplateView
 from plinth.modules import backups
 from plinth import actions
 
-from . import api, forms, SESSION_BACKUP_VARIABLE, delete_upload_backup_file
-
-# number of seconds an uploaded backup file should be kept/stored
-KEEP_UPLOADED_BACKUP_FOR = 60*10
+from . import api, forms, SESSION_BACKUP_PATH
+from .decorators import delete_tmp_backup_file
 
 subsubmenu = [{
     'url': reverse_lazy('backups:index'),
@@ -55,6 +54,7 @@ subsubmenu = [{
 }]
 
 
+@method_decorator(delete_tmp_backup_file, name='dispatch')
 class IndexView(TemplateView):
     """View to show list of archives."""
     template_name = 'backups.html'
@@ -131,23 +131,6 @@ def _get_file_response(path, filename):
     return response
 
 
-class create_temporary_backup_file:
-    """Create a temporary backup file that gets deleted after using it"""
-    # TODO: try using export-tar with FILE parameter '-' and reading stdout:
-    # https://borgbackup.readthedocs.io/en/stable/usage/tar.html
-
-    def __init__(self, name):
-        self.name = name
-        self.path = UPLOAD_BACKUP_PATH
-
-    def __enter__(self):
-        backups.export_archive(self.name, self.path)
-        return self.path
-
-    def __exit__(self, type, value, traceback):
-        delete_upload_backup_file(self.path)
-
-
 class UploadArchiveView(SuccessMessageMixin, FormView):
     form_class = forms.UploadForm
     prefix = 'backups'
@@ -163,11 +146,10 @@ class UploadArchiveView(SuccessMessageMixin, FormView):
 
     def form_valid(self, form):
         """store uploaded file."""
-        with open(UPLOAD_BACKUP_PATH, 'wb+') as destination:
+        with tempfile.NamedTemporaryFile(delete=False) as tmp_file:
+            self.request.session[SESSION_BACKUP_PATH] = tmp_file.name
             for chunk in self.request.FILES['backups-file'].chunks():
-                destination.write(chunk)
-        self.request.session[SESSION_BACKUP_VARIABLE] = time.time() + \
-                KEEP_UPLOADED_BACKUP_FOR
+                tmp_file.write(chunk)
         return super().form_valid(form)
 
 
@@ -201,7 +183,8 @@ class RestoreFromUploadView(BaseRestoreView):
     """View to restore files from an (uploaded) exported archive."""
 
     def get(self, *args, **kwargs):
-        if not os.path.isfile(UPLOAD_BACKUP_PATH):
+        path = self.request.session.get(SESSION_BACKUP_PATH)
+        if not os.path.isfile(path):
             messages.error(self.request, _('No backup file found.'))
             return redirect(reverse_lazy('backups:index'))
         else:
@@ -215,11 +198,13 @@ class RestoreFromUploadView(BaseRestoreView):
 
     def _get_included_apps(self):
         """Save some data used to instantiate the form."""
-        return backups.get_exported_archive_apps(UPLOAD_BACKUP_PATH)
+        path = self.request.session.get(SESSION_BACKUP_PATH)
+        return backups.get_exported_archive_apps(path)
 
     def form_valid(self, form):
         """Restore files from the archive on valid form submission."""
-        backups.restore_from_upload(form.cleaned_data['selected_apps'])
+        path = self.request.session.get(SESSION_BACKUP_PATH)
+        backups.restore_from_upload(path, form.cleaned_data['selected_apps'])
         return super().form_valid(form)