Add dbus service to read file stat (#142)

* add dbus file stat

* update

host_modules/file_service.py

@@ -0,0 +1,45 @@
+"""File stat handler"""
+
+from host_modules import host_service
+import subprocess
+
+MOD_NAME = 'file'
+EXIT_FAILURE = 1
+
+import os
+
+class FileService(host_service.HostModule):
+    """
+    Dbus endpoint that executes the file command
+    """
+    @host_service.method(host_service.bus_name(MOD_NAME), in_signature='s', out_signature='ia{ss}')
+    def get_file_stat(self, path):
+        if not path:
+            return EXIT_FAILURE, {'error': 'Dbus get_file_stat called with no path specified'}
+
+        try:
+            file_stat = os.stat(path)
+
+            # Get last modified time in nanoseconds since epoch
+            last_modified = int(file_stat.st_mtime * 1e9)  # Convert seconds to nanoseconds
+
+            # Get permissions in octal format
+            permissions = oct(file_stat.st_mode)[-3:]
+
+            # Get file size in bytes
+            size = file_stat.st_size
+
+            # Get current umask
+            current_umask = os.umask(0)
+            os.umask(current_umask)  # Reset umask to previous value
+
+            return 0, {
+                'path': path,
+                'last_modified': str(last_modified),  # Converting to string to maintain consistency
+                'permissions': permissions,
+                'size': str(size),  # Converting to string to maintain consistency
+                'umask': oct(current_umask)[-3:]
+            }
+
+        except Exception as e:
+            return EXIT_FAILURE, {'error': str(e)}

scripts/sonic-host-server

@@ -12,7 +12,7 @@ import dbus.service
 import dbus.mainloop.glib
 
 from gi.repository import GObject
-from host_modules import config_engine, gcu, host_service, showtech, systemd_service
+from host_modules import config_engine, gcu, host_service, showtech, systemd_service, file_service
 
 
 def register_dbus():
@@ -22,7 +22,8 @@ def register_dbus():
             'gcu': gcu.GCU('gcu'),
             'host_service': host_service.HostService('host_service'),
             'showtech': showtech.Showtech('showtech'),
-            'systemd': systemd_service.SystemdService('systemd')
+            'systemd': systemd_service.SystemdService('systemd'),
+            'file_stat': file_service.FileService('file')
             }
     for mod_name, handler_class in mod_dict.items():
         handlers[mod_name] = handler_class

tests/host_modules/file_stat_test.py

@@ -0,0 +1,57 @@
+import sys
+import os
+import pytest
+from unittest import mock
+from host_modules import file_service
+
+class TestFileService(object):
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    @mock.patch("os.stat")
+    @mock.patch("os.umask")
+    def test_get_file_stat_valid(self, mock_umask, mock_stat, MockInit, MockBusName, MockSystemBus):
+        mock_stat_result = mock.Mock()
+        mock_stat_result.st_mtime = 1609459200.0  # 2021-01-01 00:00:00 in nanoseconds
+        mock_stat_result.st_mode = 0o100644  # Regular file with permissions
+        mock_stat_result.st_size = 1024
+        mock_stat.return_value = mock_stat_result
+
+        mock_umask.return_value = 0o022  # Default umask
+
+        file_service_stub = file_service.FileService(file_service.MOD_NAME)
+        path = "/valid/path"
+        ret, msg = file_service_stub.get_file_stat(path)
+
+        assert ret == 0
+        assert msg['path'] == path
+        assert msg['last_modified'] == "1609459200000000000"
+        assert msg['permissions'] == "644"
+        assert msg['size'] == "1024"
+        assert msg['umask'] == "o22"
+
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    @mock.patch("os.stat")
+    def test_get_file_stat_invalid_path(self, mock_stat, MockInit, MockBusName, MockSystemBus):
+        mock_stat.side_effect = FileNotFoundError("[Errno 2] No such file or directory")
+
+        file_service_stub = file_service.FileService(file_service.MOD_NAME)
+        path = "/invalid/path"
+        ret, msg = file_service_stub.get_file_stat(path)
+
+        assert ret == 1
+        assert 'error' in msg
+        assert "No such file or directory" in msg['error']
+
+    @mock.patch("dbus.SystemBus")
+    @mock.patch("dbus.service.BusName")
+    @mock.patch("dbus.service.Object.__init__")
+    def test_get_file_stat_empty_path(self, MockInit, MockBusName, MockSystemBus):
+        file_service_stub = file_service.FileService(file_service.MOD_NAME)
+        path = ""
+        ret, msg = file_service_stub.get_file_stat(path)
+
+        assert ret == 1
+        assert "Dbus get_file_stat called with no path specified" in msg['error']