core: allow building and running without udev

Instead of relying on the udev daemon and GUDev to manage the devices reported
by the kernel, we can now run ModemManager relying solely on the kernel events
reported via the new ReportKernelEvent() API. Therefore, the '--no-auto-scan'
option is implicit for the ModemManager daemon when udev is disabled in the
build.

Additionally, a new custom implementation of the kernel device object is
provided, which uses sysfs to load the properties and attributes required in
each kernel device, instead of using a GUdevDevice.

The udev rule files are kept in place, and a simple custom parser is provided
which preloads all rules in memory once and then applies them to the different
kernel objects reported via ReportKernelEvent(), e.g. to set port type hints.
A simple unit test setup is prepared to validate the udev rules during the
`check' Makefile target.

src/mm-base-manager.c

@@ -17,11 +17,17 @@
  * Copyright (C) 2011 - 2016 Aleksander Morgado <aleksander@aleksander.es>
  */
 
+#include <config.h>
+
 #include <string.h>
 #include <ctype.h>
 
 #include <gmodule.h>
-#include "mm-kernel-device-udev.h"
+
+#if WITH_UDEV
+# include "mm-kernel-device-udev.h"
+#endif
+#include "mm-kernel-device-generic.h"
 
 #include <ModemManager.h>
 #include <mm-errors-types.h>
@@ -62,8 +68,6 @@ struct _MMBaseManagerPrivate {
     gchar *plugin_dir;
     /* Path to the list of initial kernel events */
     gchar *initial_kernel_events;
-    /* The UDev client */
-    GUdevClient *udev;
     /* The authorization provider */
     MMAuthProvider *authp;
     GCancellable *authp_cancellable;
@@ -76,6 +80,11 @@ struct _MMBaseManagerPrivate {
 
     /* The Test interface support */
     MmGdbusTest *test_skeleton;
+
+#if WITH_UDEV
+    /* The UDev client */
+    GUdevClient *udev;
+#endif
 };
 
 /*****************************************************************************/
@@ -346,7 +355,11 @@ handle_kernel_event (MMBaseManager            *self,
     mm_dbg ("  name:      %s", name);
     mm_dbg ("  uid:       %s", uid ? uid : "n/a");
 
+#if WITH_UDEV
     kernel_device = mm_kernel_device_udev_new_from_properties (properties, error);
+#else
+    kernel_device = mm_kernel_device_generic_new (properties, error);
+#endif
 
     if (!kernel_device)
         return FALSE;
@@ -362,6 +375,8 @@ handle_kernel_event (MMBaseManager            *self,
     return TRUE;
 }
 
+#if WITH_UDEV
+
 static void
 handle_uevent (GUdevClient *client,
                const char *action,
@@ -474,6 +489,8 @@ process_scan (MMBaseManager *self,
     g_list_free (devices);
 }
 
+#endif
+
 static void
 process_initial_kernel_events (MMBaseManager *self)
 {
@@ -534,9 +551,13 @@ mm_base_manager_start (MMBaseManager *self,
         return;
     }
 
+#if WITH_UDEV
     mm_dbg ("Starting %s device scan...", manual_scan ? "manual" : "automatic");
     process_scan (self, manual_scan);
     mm_dbg ("Finished device scan...");
+#else
+    mm_dbg ("Unsupported %s device scan...", manual_scan ? "manual" : "automatic");
+#endif
 }
 
 /*****************************************************************************/
@@ -714,11 +735,17 @@ scan_devices_auth_ready (MMAuthProvider *authp,
     if (!mm_auth_provider_authorize_finish (authp, res, &error))
         g_dbus_method_invocation_take_error (ctx->invocation, error);
     else {
+#if WITH_UDEV
         /* Otherwise relaunch device scan */
         mm_base_manager_start (MM_BASE_MANAGER (ctx->self), TRUE);
         mm_gdbus_org_freedesktop_modem_manager1_complete_scan_devices (
             MM_GDBUS_ORG_FREEDESKTOP_MODEM_MANAGER1 (ctx->self),
             ctx->invocation);
+#else
+        g_dbus_method_invocation_return_error_literal (
+            ctx->invocation, MM_CORE_ERROR, MM_CORE_ERROR_UNSUPPORTED,
+            "Cannot request manual scan of devices: unsupported");
+#endif
     }
 
     scan_devices_context_free (ctx);
@@ -771,12 +798,14 @@ report_kernel_event_auth_ready (MMAuthProvider           *authp,
     if (!mm_auth_provider_authorize_finish (authp, res, &error))
         goto out;
 
+#if WITH_UDEV
     if (ctx->self->priv->auto_scan) {
         error = g_error_new_literal (MM_CORE_ERROR, MM_CORE_ERROR_UNSUPPORTED,
                                      "Cannot report kernel event: "
                                      "udev monitoring already in place");
         goto out;
     }
+#endif
 
     properties = mm_kernel_event_properties_new_from_dictionary (ctx->dictionary, &error);
     if (!properties)
@@ -990,7 +1019,6 @@ static void
 mm_base_manager_init (MMBaseManager *manager)
 {
     MMBaseManagerPrivate *priv;
-    const gchar *subsys[5] = { "tty", "net", "usb", "usbmisc", NULL };
 
     /* Setup private data */
     manager->priv = priv = G_TYPE_INSTANCE_GET_PRIVATE (manager,
@@ -1004,8 +1032,14 @@ mm_base_manager_init (MMBaseManager *manager)
     /* Setup internal lists of device objects */
     priv->devices = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_object_unref);
 
-    /* Setup UDev client */
-    priv->udev = g_udev_client_new (subsys);
+#if WITH_UDEV
+    {
+        const gchar *subsys[5] = { "tty", "net", "usb", "usbmisc", NULL };
+
+        /* Setup UDev client */
+        priv->udev = g_udev_client_new (subsys);
+    }
+#endif
 
     /* By default, enable autoscan */
     priv->auto_scan = TRUE;
@@ -1038,9 +1072,11 @@ initable_init (GInitable *initable,
 {
     MMBaseManagerPrivate *priv = MM_BASE_MANAGER (initable)->priv;
 
+#if WITH_UDEV
     /* If autoscan enabled, list for udev events */
     if (priv->auto_scan)
         g_signal_connect (priv->udev, "uevent", G_CALLBACK (handle_uevent), initable);
+#endif
 
     /* Create plugin manager */
     priv->plugin_manager = mm_plugin_manager_new (priv->plugin_dir, error);
@@ -1086,8 +1122,10 @@ finalize (GObject *object)
 
     g_hash_table_destroy (priv->devices);
 
+#if WITH_UDEV
     if (priv->udev)
         g_object_unref (priv->udev);
+#endif
 
     if (priv->plugin_manager)
         g_object_unref (priv->plugin_manager);