dm: Use libdevmapper instead of dmsetup to get subsystem from name

src/lib/plugin_apis/dm.api

@@ -17,6 +17,7 @@ typedef enum {
     BD_DM_ERROR_RAID_FAIL,
     BD_DM_ERROR_RAID_NO_DEVS,
     BD_DM_ERROR_RAID_NO_EXIST,
+    BD_DM_ERROR_DEVICE_NOEXIST,
 } BDDMError;
 
 typedef enum {

src/plugins/dm.c

@@ -18,6 +18,7 @@
  */
 
 #include <glib.h>
+#include <string.h>
 #include <unistd.h>
 #include <blockdev/utils.h>
 #include <libdevmapper.h>
@@ -236,17 +237,67 @@ gchar* bd_dm_node_from_name (const gchar *map_name, GError **error) {
  * Tech category: %BD_DM_TECH_MAP-%BD_DM_TECH_MODE_QUERY
  */
 gchar* bd_dm_get_subsystem_from_name (const gchar *device_name, GError **error) {
-    gchar *output = NULL;
-    gboolean success = FALSE;
-    const gchar *argv[] = {"dmsetup", "info", "-co", "subsystem", "--noheadings", device_name, NULL};
+    struct dm_task *task = NULL;
+    struct dm_info info;
+    const gchar *uuid = NULL;
+    gchar *subsystem = NULL;
+    gchar *hyphen_pos = NULL;
 
-    success = bd_utils_exec_and_capture_output (argv, NULL, &output, error);
-    if (!success)
-        /* error is already populated */
+    if (geteuid () != 0) {
+        g_set_error (error, BD_DM_ERROR, BD_DM_ERROR_NOT_ROOT,
+                     "Not running as root, cannot query DM device");
         return NULL;
+    }
+
+    task = dm_task_create (DM_DEVICE_INFO);
+    if (!task) {
+        g_set_error (error, BD_DM_ERROR, BD_DM_ERROR_TASK,
+                     "Failed to create DM task");
+        return NULL;
+    }
+
+    if (!dm_task_set_name (task, device_name)) {
+        g_set_error (error, BD_DM_ERROR, BD_DM_ERROR_TASK,
+                     "Failed to set device name for DM task");
+        dm_task_destroy (task);
+        return NULL;
+    }
+
+    if (!dm_task_run (task)) {
+        g_set_error (error, BD_DM_ERROR, BD_DM_ERROR_TASK,
+                     "Failed to run DM task");
+        dm_task_destroy (task);
+        return NULL;
+    }
+
+    if (!dm_task_get_info (task, &info)) {
+        g_set_error (error, BD_DM_ERROR, BD_DM_ERROR_TASK,
+                     "Failed to get info from DM task");
+        dm_task_destroy (task);
+        return NULL;
+    }
+
+    if (!info.exists) {
+        g_set_error (error, BD_DM_ERROR, BD_DM_ERROR_DEVICE_NOEXIST,
+                     "DM device %s does not exist", device_name);
+        dm_task_destroy (task);
+        return NULL;
+    }
+
+    uuid = dm_task_get_uuid (task);
+    if (!uuid || !(*uuid)) {
+        dm_task_destroy (task);
+        return g_strdup ("");
+    }
+
+    hyphen_pos = strchr (uuid, '-');
+    if (hyphen_pos)
+        subsystem = g_strndup (uuid, hyphen_pos - uuid);
+    else
+        subsystem = g_strdup ("");
 
-    output = g_strstrip (output);
-    return output;
+    dm_task_destroy (task);
+    return subsystem;
 }
 
 /**

src/plugins/dm.h

@@ -13,6 +13,7 @@ typedef enum {
     BD_DM_ERROR_RAID_FAIL,
     BD_DM_ERROR_RAID_NO_DEVS,
     BD_DM_ERROR_RAID_NO_EXIST,
+    BD_DM_ERROR_DEVICE_NOEXIST,
 } BDDMError;
 
 typedef enum {

tests/dm_test.py

@@ -22,10 +22,6 @@ def setUpClass(cls):
         else:
             BlockDev.reinit(cls.requested_plugins, True, None)
 
-class DevMapperPluginVersionCase(DevMapperTest):
-    @tag_test(TestTags.NOSTORAGE)
-    def test_plugin_version(self):
-        self.assertEqual(BlockDev.get_plugin_soname(BlockDev.Plugin.DM), "libbd_dm.so.3")
 
 class DevMapperTestCase(DevMapperTest):
 
@@ -51,6 +47,7 @@ def _clean_up(self):
 
         os.unlink(self.dev_file)
 
+
 class DevMapperGetSubsystemFromName(DevMapperTestCase):
     def _destroy_lvm(self):
         run("vgremove --yes libbd_dm_tests --config \"devices {use_devicesfile = 0}\" >/dev/null 2>&1")
@@ -71,21 +68,51 @@ def test_get_subsystem_from_name_lvm(self):
     def test_get_subsystem_from_name_crypt(self):
         """Verify that it is possible to get luks device subsystem from its name"""
         self.addCleanup(self._destroy_crypt)
-        run("echo \"supersecretkey\" | cryptsetup luksFormat %s -" %self.loop_dev)
+        run("echo \"supersecretkey\" | cryptsetup luksFormat --pbkdf=pbkdf2 --pbkdf-force-iterations=1000 %s -" %self.loop_dev)
         run("echo \"supersecretkey\" | cryptsetup open %s libbd_dm_tests-subsystem_crypt --key-file=-" %self.loop_dev)
         subsystem = BlockDev.dm_get_subsystem_from_name("libbd_dm_tests-subsystem_crypt")
         self.assertEqual(subsystem, "CRYPT")
 
+
+    def test_get_subsystem_from_name_linear(self):
+        succ = BlockDev.dm_create_linear("testMap", self.loop_dev, 100, None)
+        self.assertTrue(succ)
+
+        # no UUID -- subsystem should be empty
+        subsystem = BlockDev.dm_get_subsystem_from_name("testMap")
+        self.assertEqual(subsystem, "")
+
+        succ = BlockDev.dm_remove("testMap")
+        self.assertTrue(succ)
+
+        # "UUID" without "prefix" -- subsystem should be empty
+        succ = BlockDev.dm_create_linear("testMap", self.loop_dev, 100, "TEST")
+        self.assertTrue(succ)
+
+        subsystem = BlockDev.dm_get_subsystem_from_name("testMap")
+        self.assertEqual(subsystem, "")
+
+        succ = BlockDev.dm_remove("testMap")
+        self.assertTrue(succ)
+
+        # non-existing device --> error
+        with self.assertRaisesRegex(GLib.GError, "does not exist"):
+            BlockDev.dm_get_subsystem_from_name("testMap")
+
+
 class DevMapperCreateRemoveLinear(DevMapperTestCase):
     @tag_test(TestTags.CORE)
     def test_create_remove_linear(self):
         """Verify that it is possible to create new linear mapping and remove it"""
 
         succ = BlockDev.dm_create_linear("testMap", self.loop_dev, 100, None)
         self.assertTrue(succ)
+        self.assertTrue(os.path.exists("/dev/mapper/testMap"))
 
         succ = BlockDev.dm_remove("testMap")
         self.assertTrue(succ)
+        self.assertFalse(os.path.exists("/dev/mapper/testMap"))
+
 
 class DevMapperMapExists(DevMapperTestCase):
     def test_map_exists(self):
@@ -115,6 +142,7 @@ def test_map_exists(self):
         succ = BlockDev.dm_map_exists("testMap", False, False)
         self.assertFalse(succ)
 
+
 class DevMapperNameNodeBijection(DevMapperTestCase):
     def test_name_node_bijection(self):
         """Verify that the map's node and map name points to each other"""
@@ -125,9 +153,11 @@ def test_name_node_bijection(self):
         self.assertEqual(BlockDev.dm_name_from_node(BlockDev.dm_node_from_name("testMap")),
                          "testMap")
 
-        self.assertTrue(succ)
 
-class DMDepsTest(DevMapperTest):
+class DMNoStorageTest(DevMapperTest):
+    @tag_test(TestTags.NOSTORAGE)
+    def test_plugin_version(self):
+        self.assertEqual(BlockDev.get_plugin_soname(BlockDev.Plugin.DM), "libbd_dm.so.3")
 
     @tag_test(TestTags.NOSTORAGE)
     def test_missing_dependencies(self):