Node device driver for HAL and DeviceKit (David Lively)

ChangeLog

+Fri Nov 21 12:23:14 BST 2008 Daniel P. Berrange <berrange@redhat.com>
+
+	Primary internal driver for node devices with HAL (default)
+	and DeviceKit (optional, unfinished) (David Lively)
+	* configure.in: Probe for HAL & DeviceKit libraries
+	* po/POTFILES.in: Add new source files
+	* qemud/Makefile.am: Link to node device driver
+	* qemud/qemud.c: Load node device driver implementation
+	* src/Makefile.am: Buid node device drivers
+	* src/libvirt_sym.version.in: Export internal symbols needed
+	by node device driver
+	* src/node_device.c, src/node_device.h: Common driver
+	routines
+	* src/node_device_hal.c: HAL specific device routines
+	* src/node_device_devkit.c: DeviceKit specific routines
+	* src/node_device_conf.h: Add dbusWatch handle field
+
 Fri Nov 21 12:20:14 BST 2008 Daniel P. Berrange <berrange@redhat.com>
 
 	* src/Makefile.am, src/node_device_conf.c, src/node_device_conf.h:

configure.in

@@ -1105,6 +1105,108 @@ test "$enable_shared" = no && lt_cv_objdir=.
 LV_LIBTOOL_OBJDIR=${lt_cv_objdir-.}
 AC_SUBST([LV_LIBTOOL_OBJDIR])
 
+dnl HAL or DeviceKit library for host device enumeration
+HAL_REQUIRED=0.0
+HAL_CFLAGS=
+HAL_LIBS=
+AC_ARG_WITH([hal],
+  [  --with-hal         use HAL for host device enumeration],
+  [],
+  [with_hal=check])
+
+if test "$with_libvirtd" = "no" ; then
+  with_hal=no
+fi
+if test "x$with_hal" = "xyes" -o "x$with_hal" = "xcheck"; then
+  PKG_CHECK_MODULES(HAL, hal >= $HAL_REQUIRED,
+    [with_hal=yes], [
+    if test "x$with_hal" = "xcheck" ; then
+       with_hal=no
+    else
+       AC_MSG_ERROR(
+         [You must install hal-devel >= $HAL_REQUIRED to compile libvirt])
+    fi
+  ])
+  if test "x$with_hal" = "xyes" ; then
+    AC_DEFINE_UNQUOTED([HAVE_HAL], 1,
+      [use HAL for host device enumeration])
+
+    old_CFLAGS=$CFLAGS
+    old_LDFLAGS=$LDFLAGS
+    CFLAGS="$CFLAGS $HAL_CFLAGS"
+    LDFLAGS="$LDFLAGS $HAL_LIBS"
+    AC_CHECK_FUNCS([libhal_get_all_devices],,[with_hal=no])
+    CFLAGS="$old_CFLAGS"
+    LDFLAGS="$old_LDFLAGS"
+  fi
+fi
+AM_CONDITIONAL([HAVE_HAL], [test "x$with_hal" = "xyes"])
+AC_SUBST([HAL_CFLAGS])
+AC_SUBST([HAL_LIBS])
+
+DEVKIT_REQUIRED=0.0
+DEVKIT_CFLAGS=
+DEVKIT_LIBS=
+AC_ARG_WITH([devkit],
+  [  --with-devkit      use DeviceKit for host device enumeration],
+  [],
+  [with_devkit=no])
+
+if test "$with_libvirtd" = "no" ; then
+  with_devkit=no
+fi
+
+dnl Extra check needed while devkit pkg-config info missing glib2 dependency
+PKG_CHECK_MODULES(GLIB2, glib-2.0 >= 0.0,,[
+  if test "x$with_devkit" = "xcheck"; then
+    with_devkit=no
+  elif test "x$with_devkit" = "xyes"; then
+    AC_MSG_ERROR([required package DeviceKit requires package glib-2.0])
+  fi])
+
+if test "x$with_devkit" = "xyes" -o "x$with_devkit" = "xcheck"; then
+  PKG_CHECK_MODULES(DEVKIT, devkit-gobject >= $DEVKIT_REQUIRED,
+    [with_devkit=yes], [
+    if test "x$with_devkit" = "xcheck" ; then
+       with_devkit=no
+    else
+       AC_MSG_ERROR(
+         [You must install DeviceKit-devel >= $DEVKIT_REQUIRED to compile libvirt])
+    fi
+  ])
+  if test "x$with_devkit" = "xyes" ; then
+    AC_DEFINE_UNQUOTED([HAVE_DEVKIT], 1,
+      [use DeviceKit for host device enumeration])
+
+    dnl Add glib2 flags explicitly while devkit pkg-config info missing glib2 dependency
+    DEVKIT_CFLAGS="$GLIB2_CFLAGS $DEVKIT_CFLAGS"
+    DEVKIT_LIBS="$GLIB2_LIBS $DEVKIT_LIBS"
+
+    dnl Add more flags apparently required for devkit to work properly
+    DEVKIT_CFLAGS="$DEVKIT_CFLAGS -D_POSIX_PTHREAD_SEMANTICS -D_REENTRANT"
+
+    old_CFLAGS=$CFLAGS
+    old_LDFLAGS=$LDFLAGS
+    CFLAGS="$CFLAGS $DEVKIT_CFLAGS"
+    LDFLAGS="$LDFLAGS $DEVKIT_LIBS"
+    AC_CHECK_FUNCS([devkit_client_connect],,[with_devkit=no])
+    CFLAGS="$old_CFLAGS"
+    LDFLAGS="$old_LDFLAGS"
+  fi
+fi
+AM_CONDITIONAL([HAVE_DEVKIT], [test "x$with_devkit" = "xyes"])
+AC_SUBST([DEVKIT_CFLAGS])
+AC_SUBST([DEVKIT_LIBS])
+
+with_nodedev=no;
+if test "$with_devkit" = "yes" -o "$with_hal" = "yes";
+then
+  with_nodedev=yes
+  AC_DEFINE_UNQUOTED([WITH_NODE_DEVICES], 1, [with node device driver])
+fi
+AM_CONDITIONAL([WITH_NODE_DEVICES], [test "$with_nodedev" = "yes"])
+
+
 # very annoying
 rm -f COPYING
 cp COPYING.LIB COPYING
@@ -1196,6 +1298,16 @@ AC_MSG_NOTICE([  xen: $XEN_CFLAGS $XEN_LIBS])
 else
 AC_MSG_NOTICE([  xen: no])
 fi
+if test "$with_hal" = "yes" ; then
+AC_MSG_NOTICE([  hal: $HAL_CFLAGS $HAL_LIBS])
+else
+AC_MSG_NOTICE([  hal: no])
+fi
+if test "$with_devkit" = "yes" ; then
+AC_MSG_NOTICE([  devkit: $DEVKIT_CFLAGS $DEVKIT_LIBS])
+else
+AC_MSG_NOTICE([  devkit: no])
+fi
 AC_MSG_NOTICE([])
 AC_MSG_NOTICE([Test suite])
 AC_MSG_NOTICE([])

po/POTFILES.in

@@ -13,6 +13,7 @@ src/lxc_controller.c
 src/lxc_driver.c
 src/network_conf.c
 src/network_driver.c
+src/node_device.c
 src/openvz_conf.c
 src/openvz_driver.c
 src/proxy_internal.c

qemud/Makefile.am

@@ -111,6 +111,10 @@ endif
 if WITH_NETWORK
 libvirtd_LDADD += ../src/libvirt_driver_network.la
 endif
+
+if WITH_NODE_DEVICES
+libvirtd_LDADD += ../src/libvirt_driver_nodedev.la
+endif
 endif
 
 libvirtd_LDADD += ../src/libvirt.la

qemud/qemud.c

@@ -79,6 +79,9 @@
 #ifdef WITH_STORAGE_DIR
 #include "storage_driver.h"
 #endif
+#ifdef WITH_NODE_DEVICES
+#include "node_device.h"
+#endif
 #endif
 
 
@@ -763,6 +766,7 @@ static struct qemud_server *qemudInitialize(int sigread) {
     virDriverLoadModule("uml");
     virDriverLoadModule("network");
     virDriverLoadModule("storage");
+    virDriverLoadModule("nodedev");
 #else
 #ifdef WITH_QEMU
     qemuRegister();
@@ -779,6 +783,9 @@ static struct qemud_server *qemudInitialize(int sigread) {
 #ifdef WITH_STORAGE_DIR
     storageRegister();
 #endif
+#if defined(HAVE_HAL) || defined(HAVE_DEVKIT)
+    nodedevRegister();
+#endif
 #endif
 
     virEventRegisterImpl(virEventAddHandleImpl,

src/Makefile.am

@@ -157,6 +157,14 @@ STORAGE_HELPER_DISK_SOURCES =					\
 		parthelper.c
 
 
+NODE_DEVICE_DRIVER_SOURCES =					\
+		node_device.c node_device.h
+
+NODE_DEVICE_DRIVER_HAL_SOURCES =				\
+		node_device_hal.c
+NODE_DEVICE_DRIVER_DEVKIT_SOURCES =				\
+		node_device_devkit.c
+
 
 #########################
 #
@@ -330,6 +338,36 @@ if WITH_STORAGE_DISK
 libvirt_driver_storage_la_SOURCES += $(STORAGE_DRIVER_DISK_SOURCES)
 endif
 
+if WITH_NODE_DEVICES
+# Needed to keep automake quiet about conditionals
+if WITH_DRIVER_MODULES
+mod_LTLIBRARIES += libvirt_driver_nodedev.la
+else
+noinst_LTLIBRARIES += libvirt_driver_nodedev.la
+# Stateful, so linked to daemon instead
+#libvirt_la_LIBADD += libvirt_driver_nodedev.la
+endif
+libvirt_driver_nodedev_la_SOURCES = $(NODE_DEVICE_DRIVER_SOURCES)
+
+libvirt_driver_nodedev_la_CFLAGS =
+libvirt_driver_nodedev_la_LDFLAGS =
+if HAVE_HAL
+libvirt_driver_nodedev_la_SOURCES += $(NODE_DEVICE_DRIVER_HAL_SOURCES)
+libvirt_driver_nodedev_la_CFLAGS += $(HAL_CFLAGS)
+libvirt_driver_nodedev_la_LDFLAGS += $(HAL_LIBS)
+endif
+if HAVE_DEVKIT
+libvirt_driver_nodedev_la_SOURCES += $(NODE_DEVICE_DRIVER_DEVKIT_SOURCES)
+libvirt_driver_nodedev_la_CFLAGS += $(DEVKIT_CFLAGS)
+libvirt_driver_nodedev_la_LDFLAGS += $(DEVKIT_LIBS)
+endif
+
+if WITH_DRIVER_MODULES
+libvirt_driver_nodedev_la_LDFLAGS += -module -avoid-version
+endif
+endif
+
+
 # Add all conditional sources just in case...
 EXTRA_DIST +=							\
 		$(TEST_DRIVER_SOURCES)				\
@@ -344,7 +382,10 @@ EXTRA_DIST +=							\
 		$(STORAGE_DRIVER_FS_SOURCES)			\
 		$(STORAGE_DRIVER_LVM_SOURCES)			\
 		$(STORAGE_DRIVER_ISCSI_SOURCES)			\
-		$(STORAGE_DRIVER_DISK_SOURCES)
+		$(STORAGE_DRIVER_DISK_SOURCES)			\
+		$(NODE_DEVICE_DRIVER_SOURCES)			\
+		$(NODE_DEVICE_DRIVER_HAL_SOURCES)		\
+		$(NODE_DEVICE_DRIVER_DEVKIT_SOURCES)
 
 
 # Empty source list - it merely links a bunch of convenience libs together

src/libvirt_sym.version.in

@@ -327,6 +327,7 @@ LIBVIRT_PRIVATE_@VERSION@ {
 	virGetNetwork;
 	virGetStoragePool;
 	virGetStorageVol;
+	virGetNodeDevice;
 	virUnrefDomain;
 
 
@@ -451,6 +452,7 @@ LIBVIRT_PRIVATE_@VERSION@ {
 	virRegisterNetworkDriver;
 	virRegisterStateDriver;
 	virRegisterStorageDriver;
+	virRegisterDeviceMonitor;
 
 
 	/* memory.h */
@@ -481,6 +483,16 @@ LIBVIRT_PRIVATE_@VERSION@ {
 	virNodeInfoPopulate;
 
 
+	/* node_device_conf.h */
+	virNodeDeviceObjRemove;
+	virNodeDevCapTypeToString;
+	virNodeDeviceFindByName;
+	virNodeDeviceObjListFree;
+	virNodeDeviceDefFree;
+	virNodeDevCapsDefFree;
+	virNodeDeviceDefFormat;
+
+
 	/* qparams.h */
 	qparam_get_query;
 	qparam_query_parse;
@@ -539,6 +551,7 @@ LIBVIRT_PRIVATE_@VERSION@ {
 	virStrToLong_i;
 	virStrToLong_ll;
 	virStrToLong_ull;
+	virStrToLong_ui;
 	virFileLinkPointsTo;
 	saferead;
 	safewrite;
@@ -558,6 +571,7 @@ LIBVIRT_PRIVATE_@VERSION@ {
 	virFileOpenTty;
 	virFileReadLimFD;
 	virFileReadPid;
+	virFileLinkPointsTo;
 	virParseNumber;
 	virRun;
 	virSkipSpaces;

src/node_device.c

+/*
+ * node_device.c: node device enumeration
+ *
+ * Copyright (C) 2008 Virtual Iron Software, Inc.
+ * Copyright (C) 2008 David F. Lively
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+ *
+ * Author: David F. Lively <dlively@virtualiron.com>
+ */
+
+#include <config.h>
+
+#include <unistd.h>
+#include <errno.h>
+
+#include "virterror_internal.h"
+#include "datatypes.h"
+#include "memory.h"
+
+#include "node_device_conf.h"
+#include "node_device.h"
+
+static int dev_has_cap(const virNodeDeviceObjPtr dev, const char *cap)
+{
+    virNodeDevCapsDefPtr caps = dev->def->caps;
+    while (caps) {
+        if (STREQ(cap, virNodeDevCapTypeToString(caps->type)))
+            return 1;
+        caps = caps->next;
+    }
+    return 0;
+}
+
+
+static int nodeNumOfDevices(virConnectPtr conn,
+                            const char *cap,
+                            unsigned int flags ATTRIBUTE_UNUSED)
+{
+    virDeviceMonitorStatePtr driver = conn->devMonPrivateData;
+    int ndevs = 0;
+    unsigned int i;
+
+    for (i = 0; i < driver->devs.count; i++)
+        if ((cap == NULL) ||
+            dev_has_cap(driver->devs.objs[i], cap))
+            ++ndevs;
+
+    return ndevs;
+}
+
+static int
+nodeListDevices(virConnectPtr conn,
+                const char *cap,
+                char **const names, int maxnames,
+                unsigned int flags ATTRIBUTE_UNUSED)
+{
+    virDeviceMonitorStatePtr driver = conn->devMonPrivateData;
+    int ndevs = 0;
+    unsigned int i;
+
+    for (i = 0; i < driver->devs.count && ndevs < maxnames; i++)
+        if (cap == NULL ||
+            dev_has_cap(driver->devs.objs[i], cap))
+            if ((names[ndevs++] = strdup(driver->devs.objs[i]->def->name)) == NULL)
+                goto failure;
+
+    return ndevs;
+
+ failure:
+    --ndevs;
+    while (--ndevs >= 0)
+        VIR_FREE(names[ndevs]);
+    return -1;
+}
+
+
+static virNodeDevicePtr nodeDeviceLookupByName(virConnectPtr conn,
+                                               const char *name)
+{
+    virDeviceMonitorStatePtr driver = conn->devMonPrivateData;
+    virNodeDeviceObjPtr obj = virNodeDeviceFindByName(&driver->devs, name);
+
+    if (!obj) {
+        virNodeDeviceReportError(conn, VIR_ERR_INVALID_NODE_DEVICE,
+                                 "%s", _("no node device with matching name"));
+        return NULL;
+    }
+
+    return virGetNodeDevice(conn, name);
+
+}
+
+static char *nodeDeviceDumpXML(virNodeDevicePtr dev,
+                               unsigned int flags ATTRIBUTE_UNUSED)
+{
+    virDeviceMonitorStatePtr driver = dev->conn->devMonPrivateData;
+    virNodeDeviceObjPtr obj = virNodeDeviceFindByName(&driver->devs, dev->name);
+
+    if (!obj) {
+        virNodeDeviceReportError(dev->conn, VIR_ERR_INVALID_NODE_DEVICE,
+                              "%s", _("no node device with matching name"));
+        return NULL;
+    }
+
+    return virNodeDeviceDefFormat(dev->conn, obj->def);
+}
+
+
+static char *nodeDeviceGetParent(virNodeDevicePtr dev)
+{
+    virDeviceMonitorStatePtr driver = dev->conn->devMonPrivateData;
+    virNodeDeviceObjPtr obj = virNodeDeviceFindByName(&driver->devs, dev->name);
+
+    if (!obj) {
+        virNodeDeviceReportError(dev->conn, VIR_ERR_INVALID_NODE_DEVICE,
+                              "%s", _("no node device with matching name"));
+        return NULL;
+    }
+
+    return obj->def->parent;
+}
+
+
+static int nodeDeviceNumOfCaps(virNodeDevicePtr dev)
+{
+    virDeviceMonitorStatePtr driver = dev->conn->devMonPrivateData;
+    virNodeDeviceObjPtr obj = virNodeDeviceFindByName(&driver->devs, dev->name);
+    virNodeDevCapsDefPtr caps;
+    int ncaps = 0;
+
+    if (!obj) {
+        virNodeDeviceReportError(dev->conn, VIR_ERR_INVALID_NODE_DEVICE,
+                              "%s", _("no node device with matching name"));
+        return -1;
+    }
+
+    for (caps = obj->def->caps; caps; caps = caps->next)
+        ++ncaps;
+
+    return ncaps;
+}
+
+
+static int
+nodeDeviceListCaps(virNodeDevicePtr dev, char **const names, int maxnames)
+{
+    virDeviceMonitorStatePtr driver = dev->conn->devMonPrivateData;
+    virNodeDeviceObjPtr obj = virNodeDeviceFindByName(&driver->devs, dev->name);
+    virNodeDevCapsDefPtr caps;
+    int ncaps = 0;
+
+    if (!obj) {
+        virNodeDeviceReportError(dev->conn, VIR_ERR_INVALID_NODE_DEVICE,
+                              "%s", _("no node device with matching name"));
+        return -1;
+    }
+
+    for (caps = obj->def->caps; caps && ncaps < maxnames; caps = caps->next) {
+        names[ncaps] = strdup(virNodeDevCapTypeToString(caps->type));
+        if (names[ncaps++] == NULL)
+            goto failure;
+    }
+
+    return ncaps;
+
+ failure:
+    --ncaps;
+    while (--ncaps >= 0)
+        VIR_FREE(names[ncaps]);
+    return -1;
+}
+
+
+void registerCommonNodeFuncs(virDeviceMonitorPtr driver)
+{
+    driver->numOfDevices = nodeNumOfDevices;
+    driver->listDevices = nodeListDevices;
+    driver->deviceLookupByName = nodeDeviceLookupByName;
+    driver->deviceDumpXML = nodeDeviceDumpXML;
+    driver->deviceGetParent = nodeDeviceGetParent;
+    driver->deviceNumOfCaps = nodeDeviceNumOfCaps;
+    driver->deviceListCaps = nodeDeviceListCaps;
+}
+
+
+int nodedevRegister(void) {
+#if defined(HAVE_HAL) && defined(HAVE_DEVKIT)
+    /* Register only one of these two - they conflict */
+    if (halNodeRegister() == -1)
+        return devkitNodeRegister();
+    return 0;
+#else
+#ifdef HAVE_HAL
+    return halNodeRegister();
+#endif
+#ifdef HAVE_DEVKIT
+    return devkitNodeRegister();
+#endif
+#endif
+}

src/node_device.h

+/*
+ * node_device.h: node device enumeration
+ *
+ * Copyright (C) 2008 Virtual Iron Software, Inc.
+ * Copyright (C) 2008 David F. Lively
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+ *
+ * Author: David F. Lively <dlively@virtualiron.com>
+ */
+
+#ifndef __VIR_NODE_DEVICE_H__
+#define __VIR_NODE_DEVICE_H__
+
+#include "internal.h"
+#include "driver.h"
+
+#ifdef HAVE_HAL
+int halNodeRegister(void);
+#endif
+#ifdef HAVE_DEVKIT
+int devkitNodeRegister(void);
+#endif
+
+void registerCommonNodeFuncs(virDeviceMonitorPtr mon);
+
+int nodedevRegister(void);
+
+#endif /* __VIR_NODE_DEVICE_H__ */

src/node_device_conf.h

@@ -161,6 +161,7 @@ struct _virNodeDeviceObjList {
 typedef struct _virDeviceMonitorState virDeviceMonitorState;
 typedef virDeviceMonitorState *virDeviceMonitorStatePtr;
 struct _virDeviceMonitorState {
+    int dbusWatch;
     virNodeDeviceObjList devs;		/* currently-known devices */
     void *privateData;			/* driver-specific private data */
 };

src/node_device_devkit.c

+/*
+ * node_device_devkit.c: node device enumeration - DeviceKit-based implementation
+ *
+ * Copyright (C) 2008 Virtual Iron Software, Inc.
+ * Copyright (C) 2008 David F. Lively
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+ *
+ * Author: David F. Lively <dlively@virtualiron.com>
+ */
+
+#include <config.h>
+#include <devkit-gobject.h>
+
+#include "node_device_conf.h"
+#include "virterror_internal.h"
+#include "driver.h"
+#include "datatypes.h"
+#include "event.h"
+#include "memory.h"
+#include "uuid.h"
+
+#include "node_device.h"
+
+/*
+ * Host device enumeration (DeviceKit implementation)
+ */
+
+static virDeviceMonitorStatePtr driverState;
+
+#define DEBUG(fmt,...) VIR_DEBUG(__FILE__, fmt, __VA_ARGS__)
+#define DEBUG0(msg) VIR_DEBUG(__FILE__, "%s", msg)
+
+#define CONN_DRV_STATE(conn) \
+        ((virDeviceMonitorStatePtr)((conn)->devMonPrivateData))
+#define DRV_STATE_DKCLIENT(ds) ((DevkitClient *)((ds)->privateData))
+#define CONN_DKCLIENT(conn) DRV_STATE_DKCLIENT(CONN_DRV_STATE(conn))
+
+#define NODE_DEV_DKDEV(obj) ((DevkitDevice *)((obj)->privateData)
+
+static int get_str_prop(DevkitDevice *dkdev, const char *prop, char **val_p)
+{
+    char *val = devkit_device_dup_property_as_str(dkdev, prop);
+
+    if (val) {
+        if (*val) {
+            *val_p = val;
+            return 0;
+        } else {
+            /* Treat empty strings as NULL values */
+            VIR_FREE(val);
+        }
+    }
+
+    return -1;
+}
+
+#if 0
+static int get_int_prop(DevkitDevice *dkdev, const char *prop, int *val_p)
+{
+    if (! devkit_device_has_property(dkdev, prop))
+        return -1;
+    *val_p = devkit_device_get_property_as_int(dkdev, prop);
+    return 0;
+}
+
+static int get_uint64_prop(DevkitDevice *dkdev, const char *prop,
+                           unsigned long long *val_p)
+{
+    if (! devkit_device_has_property(dkdev, prop))
+        return -1;
+    *val_p = devkit_device_get_property_as_uint64(dkdev, prop);
+    return 0;
+}
+#endif
+
+static int gather_pci_cap(DevkitDevice *dkdev,
+                          union _virNodeDevCapData *d)
+{
+    const char *sysfs_path = devkit_device_get_native_path(dkdev);
+
+    if (sysfs_path != NULL) {
+        char *p = strrchr(sysfs_path, '/');
+        if (p) {
+            (void)virStrToLong_ui(p+1, &p, 16, &d->pci_dev.domain);
+            (void)virStrToLong_ui(p+1, &p, 16, &d->pci_dev.bus);
+            (void)virStrToLong_ui(p+1, &p, 16, &d->pci_dev.slot);
+            (void)virStrToLong_ui(p+1, &p, 16, &d->pci_dev.function);
+        }
+    }
+    return 0;
+}
+
+
+static int gather_usb_cap(DevkitDevice *dkdev,
+                          union _virNodeDevCapData *d)
+{
+    (void)get_str_prop(dkdev, "ID_VENDOR", &d->usb_dev.vendor_name);
+    (void)get_str_prop(dkdev, "ID_MODEL", &d->usb_dev.product_name);
+    return 0;
+}
+
+
+static int gather_net_cap(DevkitDevice *dkdev,
+                          union _virNodeDevCapData *d)
+{
+    const char *sysfs_path = devkit_device_get_native_path(dkdev);
+    const char *interface;
+
+    if (sysfs_path == NULL)
+        return -1;
+    interface = strrchr(sysfs_path, '/');
+    if (!interface || !*interface || !*(++interface))
+        return -1;
+    if ((d->net.interface = strdup(interface)) == NULL)
+        return -1;
+
+    d->net.subtype = VIR_NODE_DEV_CAP_NET_LAST;
+
+    return 0;
+}
+
+
+static int gather_block_cap(DevkitDevice *dkdev,
+                          union _virNodeDevCapData *d)
+{
+    const char *device = devkit_device_get_device_file(dkdev);
+
+    if (device && ((d->block.device = strdup(device)) == NULL))
+        return -1;
+
+    return 0;
+}
+
+
+struct _caps_tbl_entry {
+    const char *cap_name;
+    enum virNodeDevCapType type;
+    int (*gather_fn)(DevkitDevice *dkdev,
+                     union _virNodeDevCapData *data);
+};
+
+typedef struct _caps_tbl_entry caps_tbl_entry;
+
+static caps_tbl_entry caps_tbl[] = {
+    { "pci",        VIR_NODE_DEV_CAP_PCI_DEV,   gather_pci_cap },
+    { "usb",        VIR_NODE_DEV_CAP_USB_DEV,   gather_usb_cap },
+    { "net",        VIR_NODE_DEV_CAP_NET,       gather_net_cap },
+    { "block",      VIR_NODE_DEV_CAP_BLOCK,     gather_block_cap },
+    // TODO: more caps!
+};
+
+
+/* qsort/bsearch string comparator */
+static int cmpstringp(const void *p1, const void *p2)
+{
+    /* from man 3 qsort */
+    return strcmp(* (char * const *) p1, * (char * const *) p2);
+}
+
+
+static int gather_capability(DevkitDevice *dkdev,
+                             const char *cap_name,
+                             virNodeDevCapsDefPtr *caps_p)
+{
+    size_t caps_tbl_len = sizeof(caps_tbl) / sizeof(caps_tbl[0]);
+    caps_tbl_entry *entry;
+
+    entry = bsearch(&cap_name, caps_tbl, caps_tbl_len,
+                    sizeof(caps_tbl[0]), cmpstringp);
+
+    if (entry) {
+        virNodeDevCapsDefPtr caps;
+        if (VIR_ALLOC(caps) < 0)
+            return ENOMEM;
+        caps->type = entry->type;
+        if (entry->gather_fn) {
+            int rv = (*entry->gather_fn)(dkdev, &caps->data);
+            if (rv != 0) {
+                virNodeDevCapsDefFree(caps);
+                return rv;
+            }
+        }
+        caps->next = *caps_p;
+        *caps_p = caps;
+    }
+
+    return 0;
+}
+
+
+static int gather_capabilities(DevkitDevice *dkdev,
+                               virNodeDevCapsDefPtr *caps_p)
+{
+    const char *subsys = devkit_device_get_subsystem(dkdev);
+    const char *bus_name = devkit_device_get_property(dkdev, "ID_BUS");
+    virNodeDevCapsDefPtr caps = NULL;
+    int rv;
+
+    if (subsys) {
+        rv = gather_capability(dkdev, subsys, &caps);
+        if (rv != 0) goto failure;
+    }
+
+    if (bus_name && (subsys == NULL || !STREQ(bus_name, subsys))) {
+        rv = gather_capability(dkdev, bus_name, &caps);
+        if (rv != 0) goto failure;
+    }
+
+    *caps_p = caps;
+    return 0;
+
+ failure:
+    while (caps) {
+        virNodeDevCapsDefPtr next = caps->next;
+        virNodeDevCapsDefFree(caps);
+        caps = next;
+    }
+    return rv;
+}
+
+static void dev_create(void *_dkdev, void *_dkclient ATTRIBUTE_UNUSED)
+{
+    DevkitDevice *dkdev = _dkdev;
+    const char *sysfs_path = devkit_device_get_native_path(dkdev);
+    virNodeDeviceObjPtr dev = NULL;
+    const char *name;
+    int rv;
+
+    if (sysfs_path == NULL)
+        /* Currently using basename(sysfs_path) as device name (key) */
+        return;
+
+    name = strrchr(sysfs_path, '/');
+    if (name == NULL)
+        name = sysfs_path;
+    else
+        ++name;
+
+    if (VIR_ALLOC(dev) < 0 || VIR_ALLOC(dev->def) < 0)
+        goto failure;
+
+    dev->privateData = dkdev;
+
+    if ((dev->def->name = strdup(name)) == NULL)
+        goto failure;
+
+    // TODO: Find device parent, if any
+
+    rv = gather_capabilities(dkdev, &dev->def->caps);
+    if (rv != 0) goto failure;
+
+    if (VIR_REALLOC_N(driverState->devs.objs, driverState->devs.count + 1) < 0)
+        goto failure;
+
+    driverState->devs.objs[driverState->devs.count++] = dev;
+
+    return;
+
+ failure:
+    DEBUG("FAILED TO ADD dev %s", name);
+    if (dev)
+        virNodeDeviceDefFree(dev->def);
+    VIR_FREE(dev);
+}
+
+
+static int devkitDeviceMonitorStartup(void)
+{
+    size_t caps_tbl_len = sizeof(caps_tbl) / sizeof(caps_tbl[0]);
+    DevkitClient *devkit_client = NULL;
+    GError *err = NULL;
+    GList *devs;
+    int i;
+
+    /* Ensure caps_tbl is sorted by capability name */
+    qsort(caps_tbl, caps_tbl_len, sizeof(caps_tbl[0]), cmpstringp);
+
+    if (VIR_ALLOC(driverState) < 0)
+        return -1;
+
+    // TODO: Is it really ok to call this multiple times??
+    //       Is there something analogous to call on close?
+    g_type_init();
+
+    /* Get new devkit_client and connect to daemon */
+    devkit_client = devkit_client_new(NULL);
+    if (devkit_client == NULL) {
+        DEBUG0("devkit_client_new returned NULL");
+        goto failure;
+    }
+    if (!devkit_client_connect(devkit_client, &err)) {
+        DEBUG0("devkit_client_connect failed");
+        goto failure;
+    }
+
+    /* Populate with known devices.
+     *
+     * This really should be:
+        devs = devkit_client_enumerate_by_subsystem(devkit_client, NULL, &err);
+        if (err) {
+            DEBUG0("devkit_client_enumerate_by_subsystem failed");
+            devs = NULL;
+            goto failure;
+        }
+        g_list_foreach(devs, dev_create, devkit_client);
+    * but devkit_client_enumerate_by_subsystem currently fails when the second
+    * arg is null (contrary to the API documentation).  So the following code
+    * (from Dan B) works around this by listing devices per handled subsystem.
+    */
+
+    for (i = 0 ; i < ARRAY_CARDINALITY(caps_tbl) ; i++) {
+        const char *caps[] = { caps_tbl[i].cap_name, NULL };
+        devs = devkit_client_enumerate_by_subsystem(devkit_client,
+                                                    caps,
+                                                    &err);
+        if (err) {
+            DEBUG0("devkit_client_enumerate_by_subsystem failed");
+            devs = NULL;
+            goto failure;
+        }
+        g_list_foreach(devs, dev_create, devkit_client);
+    }
+
+    driverState->privateData = devkit_client;
+
+    // TODO: Register to get DeviceKit events on device changes and
+    //       coordinate updates with queries and other operations.
+
+    return 0;
+
+ failure:
+    if (err) {
+        DEBUG("\terror[%d]: %s", err->code, err->message);
+        g_error_free(err);
+    }
+    if (devs) {
+        g_list_foreach(devs, (GFunc)g_object_unref, NULL);
+        g_list_free(devs);
+    }
+    if (devkit_client)
+        g_object_unref(devkit_client);
+    VIR_FREE(driverState);
+
+    return -1;
+}
+
+
+static int devkitDeviceMonitorShutdown(void)
+{
+    if (driverState) {
+        DevkitClient *devkit_client = DRV_STATE_DKCLIENT(driverState);
+        virNodeDeviceObjListFree(&driverState->devs);
+        if (devkit_client)
+            g_object_unref(devkit_client);
+        VIR_FREE(driverState);
+        return 0;
+    }
+    return -1;
+}
+
+
+static int devkitDeviceMonitorReload(void)
+{
+    (void)devkitDeviceMonitorShutdown();
+    return devkitDeviceMonitorStartup();
+}
+
+
+static int devkitDeviceMonitorActive(void)
+{
+    /* Always ready to deal with a shutdown */
+    return 0;
+}
+
+
+static virDrvOpenStatus
+devkitNodeDrvOpen(virConnectPtr conn,
+                  virConnectAuthPtr auth ATTRIBUTE_UNUSED,
+                  int flags ATTRIBUTE_UNUSED)
+{
+    if (driverState == NULL)
+        return VIR_DRV_OPEN_DECLINED;
+
+    conn->devMonPrivateData = driverState;
+
+    return VIR_DRV_OPEN_SUCCESS;
+}
+
+static int devkitNodeDrvClose(virConnectPtr conn ATTRIBUTE_UNUSED)
+{
+    conn->devMonPrivateData = NULL;
+    return 0;
+}
+
+
+static virDeviceMonitor devkitDeviceMonitor = {
+    .name = "devkitDeviceMonitor",
+    .open = devkitNodeDrvOpen,
+    .close = devkitNodeDrvClose,
+};
+
+
+static virStateDriver devkitStateDriver = {
+    .initialize = devkitDeviceMonitorStartup,
+    .cleanup = devkitDeviceMonitorShutdown,
+    .reload = devkitDeviceMonitorReload,
+    .active = devkitDeviceMonitorActive,
+};
+
+int devkitNodeRegister(void)
+{
+    registerCommonNodeFuncs(&devkitDeviceMonitor);
+    if (virRegisterDeviceMonitor(&devkitDeviceMonitor) < 0)
+        return -1;
+    return virRegisterStateDriver(&devkitStateDriver);
+}