platform: avoid copying arguments for nmp_utils_ethtool_get_driver_info()

We call nmp_utils_ethtool_get_driver_info() twice when receiving a
netlink message, but we don't need a clone of the string values.
Instead, expose a data structure that should be stack allocated
by the caller.

src/platform/nm-linux-platform.c

@@ -676,21 +676,21 @@ _linktype_get_type (NMPlatform *platform,
 		return NM_LINK_TYPE_IP6TNL;
 
 	if (ifname) {
+		NMPUtilsEthtoolDriverInfo driver_info;
 		nm_auto_close int dirfd = -1;
-		gs_free char *driver = NULL;
 		gs_free char *devtype = NULL;
 		char ifname_verified[IFNAMSIZ];
 
 		/* Fallback OVS detection for kernel <= 3.16 */
-		if (nmp_utils_ethtool_get_driver_info (ifindex, &driver, NULL, NULL)) {
+		if (nmp_utils_ethtool_get_driver_info (ifindex, &driver_info)) {
-			if (!g_strcmp0 (driver, "openvswitch"))
+			if (nm_streq (driver_info.driver, "openvswitch"))
 				return NM_LINK_TYPE_OPENVSWITCH;
 
 			if (arptype == 256) {
 				/* Some s390 CTC-type devices report 256 for the encapsulation type
 				 * for some reason, but we need to call them Ethernet.
 				 */
-				if (!g_strcmp0 (driver, "ctcm"))
+				if (nm_streq (driver_info.driver, "ctcm"))
 					return NM_LINK_TYPE_ETHERNET;
 			}
 		}
@@ -5535,14 +5535,17 @@ link_get_driver_info (NMPlatform *platform,
                       char **out_fw_version)
 {
 	nm_auto_pop_netns NMPNetns *netns = NULL;
+	NMPUtilsEthtoolDriverInfo driver_info;
 
 	if (!nm_platform_netns_push (platform, &netns))
 		return FALSE;
 
-	return nmp_utils_ethtool_get_driver_info (ifindex,
+	if (!nmp_utils_ethtool_get_driver_info (ifindex, &driver_info))
-	                                          out_driver_name,
+		return FALSE;
-	                                          out_driver_version,
+	NM_SET_OUT (out_driver_name,    g_strdup (driver_info.driver));
-	                                          out_fw_version);
+	NM_SET_OUT (out_driver_version, g_strdup (driver_info.version));
+	NM_SET_OUT (out_fw_version,     g_strdup (driver_info.fw_version));
+	return TRUE;
 }
 
 /*****************************************************************************/

src/platform/nm-platform-utils.c

@@ -172,26 +172,25 @@ ethtool_get_stringset_index (int ifindex, int stringset_id, const char *string)
 
 gboolean
 nmp_utils_ethtool_get_driver_info (int ifindex,
-                                   char **out_driver_name,
+                                   NMPUtilsEthtoolDriverInfo *data)
-                                   char **out_driver_version,
-                                   char **out_fw_version)
 {
-	struct ethtool_drvinfo drvinfo = { 0 };
+	struct ethtool_drvinfo *drvinfo;
+	G_STATIC_ASSERT (sizeof (*data) == sizeof (*drvinfo));
+	G_STATIC_ASSERT (offsetof (NMPUtilsEthtoolDriverInfo, driver)     == offsetof (struct ethtool_drvinfo, driver));
+	G_STATIC_ASSERT (offsetof (NMPUtilsEthtoolDriverInfo, version)    == offsetof (struct ethtool_drvinfo, version));
+	G_STATIC_ASSERT (offsetof (NMPUtilsEthtoolDriverInfo, fw_version) == offsetof (struct ethtool_drvinfo, fw_version));
+	G_STATIC_ASSERT (sizeof (data->driver)     == sizeof (drvinfo->driver));
+	G_STATIC_ASSERT (sizeof (data->version)    == sizeof (drvinfo->version));
+	G_STATIC_ASSERT (sizeof (data->fw_version) == sizeof (drvinfo->fw_version));
 
 	g_return_val_if_fail (ifindex > 0, FALSE);
+	g_return_val_if_fail (data, FALSE);
 
-	drvinfo.cmd = ETHTOOL_GDRVINFO;
+	drvinfo = (struct ethtool_drvinfo *) data;
-	if (!ethtool_get (ifindex, &drvinfo))
-		return FALSE;
 
-	if (out_driver_name)
+	memset (drvinfo, 0, sizeof (*drvinfo));
-		*out_driver_name = g_strdup (drvinfo.driver);
+	drvinfo->cmd = ETHTOOL_GDRVINFO;
-	if (out_driver_version)
+	return ethtool_get (ifindex, drvinfo);
-		*out_driver_version = g_strdup (drvinfo.version);
-	if (out_fw_version)
-		*out_fw_version = g_strdup (drvinfo.fw_version);
-
-	return TRUE;
 }
 
 gboolean

src/platform/nm-platform-utils.h

@@ -38,10 +38,25 @@ gboolean nmp_utils_ethtool_set_wake_on_lan (int ifindex, NMSettingWiredWakeOnLan
 gboolean nmp_utils_ethtool_get_link_settings (int ifindex, gboolean *out_autoneg, guint32 *out_speed, NMPlatformLinkDuplexType *out_duplex);
 gboolean nmp_utils_ethtool_set_link_settings (int ifindex, gboolean autoneg, guint32 speed, NMPlatformLinkDuplexType duplex);
 
+typedef struct {
+	/* We don't want to include <linux/ethtool.h> in header files,
+	 * thus create a ABI compatible version of struct ethtool_drvinfo.*/
+	guint32 _private_cmd;
+	char    driver[32];
+	char    version[32];
+	char    fw_version[32];
+	char    _private_bus_info[32];
+	char    _private_erom_version[32];
+	char    _private_reserved2[12];
+	guint32 _private_n_priv_flags;
+	guint32 _private_n_stats;
+	guint32 _private_testinfo_len;
+	guint32 _private_eedump_len;
+	guint32 _private_regdump_len;
+} NMPUtilsEthtoolDriverInfo;
+
 gboolean nmp_utils_ethtool_get_driver_info (int ifindex,
-                                            char **out_driver_name,
+                                            NMPUtilsEthtoolDriverInfo *data);
-                                            char **out_driver_version,
-                                            char **out_fw_version);
 
 gboolean  nmp_utils_ethtool_get_permanent_address (int ifindex,
                                                    guint8 *buf,

src/platform/nmp-object.c

@@ -141,13 +141,11 @@ _link_get_driver (GUdevDevice *udev_device, const char *kind, int ifindex)
 		return kind;
 
 	if (ifindex > 0) {
-		char *d;
+		NMPUtilsEthtoolDriverInfo driver_info;
 
-		if (nmp_utils_ethtool_get_driver_info (ifindex, &d, NULL, NULL)) {
+		if (nmp_utils_ethtool_get_driver_info (ifindex, &driver_info)) {
-			driver = d && d[0] ? g_intern_string (d) : NULL;
+			if (driver_info.driver[0])
-			g_free (d);
+				return g_intern_string (driver_info.driver);
-			if (driver)
-				return driver;
 		}
 	}
 

src/platform/tests/test-link.c

@@ -1956,6 +1956,7 @@ test_netns_general (gpointer fixture, gconstpointer test_data)
 	char sbuf[100];
 	int i, j, k;
 	gboolean ethtool_support;
+	NMPUtilsEthtoolDriverInfo driver_info;
 
 	if (_test_netns_check_skip ())
 		return;
@@ -2026,8 +2027,8 @@ test_netns_general (gpointer fixture, gconstpointer test_data)
 	 * skip asserts that are known to fail. */
 	ethtool_support = nmtstp_run_command ("ethtool -i dummy1_ > /dev/null") == 0;
 	if (ethtool_support) {
-		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_1, 0, "dummy1_", NM_LINK_TYPE_DUMMY)->ifindex, NULL, NULL, NULL));
+		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_1, 0, "dummy1_", NM_LINK_TYPE_DUMMY)->ifindex, &driver_info));
-		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_1, 0, "dummy2a", NM_LINK_TYPE_DUMMY)->ifindex, NULL, NULL, NULL));
+		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_1, 0, "dummy2a", NM_LINK_TYPE_DUMMY)->ifindex, &driver_info));
 		g_assert_cmpint (nmtstp_run_command ("ethtool -i dummy1_ > /dev/null"), ==, 0);
 		g_assert_cmpint (nmtstp_run_command ("ethtool -i dummy2a > /dev/null"), ==, 0);
 		g_assert_cmpint (nmtstp_run_command ("ethtool -i dummy2b 2> /dev/null"), !=, 0);
@@ -2036,8 +2037,8 @@ test_netns_general (gpointer fixture, gconstpointer test_data)
 	g_assert (nm_platform_netns_push (platform_2, &netns_tmp));
 
 	if (ethtool_support) {
-		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_2, 0, "dummy1_", NM_LINK_TYPE_DUMMY)->ifindex, NULL, NULL, NULL));
+		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_2, 0, "dummy1_", NM_LINK_TYPE_DUMMY)->ifindex, &driver_info));
-		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_2, 0, "dummy2b", NM_LINK_TYPE_DUMMY)->ifindex, NULL, NULL, NULL));
+		g_assert (nmp_utils_ethtool_get_driver_info (nmtstp_link_get_typed (platform_2, 0, "dummy2b", NM_LINK_TYPE_DUMMY)->ifindex, &driver_info));
 		g_assert_cmpint (nmtstp_run_command ("ethtool -i dummy1_ > /dev/null"), ==, 0);
 		g_assert_cmpint (nmtstp_run_command ("ethtool -i dummy2a 2> /dev/null"), !=, 0);
 		g_assert_cmpint (nmtstp_run_command ("ethtool -i dummy2b > /dev/null"), ==, 0);