core: use nmp_utils_sysctl_open_netdir() to read tun/tap sysctl

src/devices/nm-device-tun.c

@@ -80,7 +80,7 @@ reload_tun_properties (NMDeviceTun *self)
 
 	ifindex = nm_device_get_ifindex (NM_DEVICE (self));
 	if (ifindex > 0) {
-		if (!nm_platform_link_tun_get_properties (NM_PLATFORM_GET, ifindex, &props)) {
+		if (!nm_platform_link_tun_get_properties (NM_PLATFORM_GET, ifindex, NULL, &props)) {
 			_LOGD (LOGD_DEVICE, "tun-properties: cannot loading tun properties from platform for ifindex %d", ifindex);
 			ifindex = 0;
 		} else if (g_strcmp0 (priv->mode, props.mode) != 0) {
@@ -181,7 +181,7 @@ update_connection (NMDevice *device, NMConnection *connection)
 		nm_connection_add_setting (connection, (NMSetting *) s_tun);
 	}
 
-	if (!nm_platform_link_tun_get_properties (NM_PLATFORM_GET, nm_device_get_ifindex (device), &props)) {
+	if (!nm_platform_link_tun_get_properties (NM_PLATFORM_GET, nm_device_get_ifindex (device), NULL, &props)) {
 		_LOGW (LOGD_PLATFORM, "failed to get TUN interface info while updating connection.");
 		return;
 	}

src/platform/nm-linux-platform.c

@@ -656,7 +656,7 @@ _linktype_get_type (NMPlatform *platform,
 			NMPlatformTunProperties props;
 
 			if (   platform
-			    && nm_platform_link_tun_get_properties_ifname (platform, ifname, &props)) {
+			    && nm_platform_link_tun_get_properties (platform, ifindex, ifname ?: "", &props)) {
 				if (!g_strcmp0 (props.mode, "tap"))
 					return NM_LINK_TYPE_TAP;
 				if (!g_strcmp0 (props.mode, "tun"))

src/platform/nm-platform.c

@@ -2259,74 +2259,59 @@ nm_platform_link_veth_get_properties (NMPlatform *self, int ifindex, int *out_pe
 }
 
 gboolean
-nm_platform_link_tun_get_properties_ifname (NMPlatform *self, const char *ifname, NMPlatformTunProperties *props)
+nm_platform_link_tun_get_properties (NMPlatform *self, int ifindex, const char *ifname_guess, NMPlatformTunProperties *props)
 {
-	char path[256];
+	nm_auto_close int dirfd = -1;
-	char *val;
+	const char *ifname;
+	char ifname_verified[IFNAMSIZ];
+	gint64 flags;
 	gboolean success = TRUE;
-
 	_CHECK_SELF (self, klass, FALSE);
 
+	g_return_val_if_fail (ifindex > 0, FALSE);
 	g_return_val_if_fail (props, FALSE);
 
+	/* ifname_guess is an optional argument to find a guess for the ifname corresponding to
+	 * ifindex. */
+	if (!ifname_guess) {
+		/* if NULL, obtain the guess from the platform cache. */
+		ifname = nm_platform_link_get_name (self, ifindex);
+	} else if (!ifname_guess[0]) {
+		/* if empty, don't use a guess. That means to use if_indextoname(). */
+		ifname = NULL;
+	} else
+		ifname = ifname_guess;
+
 	memset (props, 0, sizeof (*props));
 	props->owner = -1;
 	props->group = -1;
 
-	if (!ifname || !nm_utils_iface_valid_name (ifname))
+	dirfd = nm_platform_sysctl_open_netdir (self, ifindex, ifname_verified);
+	if (dirfd < 0)
 		return FALSE;
 
-	nm_sprintf_buf (path, "/sys/class/net/%s/owner", ifname);
+	ifname = ifname_verified;
-	val = nm_platform_sysctl_get (self, NMP_SYSCTL_PATHID_ABSOLUTE (path));
+
-	if (val) {
+	props->owner = nm_platform_sysctl_get_int_checked (self, NMP_SYSCTL_PATHID_NETDIR (dirfd, ifname, "owner"), 10, -1, G_MAXINT64, -1);
-		props->owner = _nm_utils_ascii_str_to_int64 (val, 10, -1, G_MAXINT64, -1);
 	if (errno)
 		success = FALSE;
-		g_free (val);
-	} else
-		success = FALSE;
 
-	nm_sprintf_buf (path, "/sys/class/net/%s/group", ifname);
+	props->group = nm_platform_sysctl_get_int_checked (self, NMP_SYSCTL_PATHID_NETDIR (dirfd, ifname, "group"), 10, -1, G_MAXINT64, -1);
-	val = nm_platform_sysctl_get (self, NMP_SYSCTL_PATHID_ABSOLUTE (path));
-	if (val) {
-		props->group = _nm_utils_ascii_str_to_int64 (val, 10, -1, G_MAXINT64, -1);
 	if (errno)
 		success = FALSE;
-		g_free (val);
-	} else
-		success = FALSE;
 
-	nm_sprintf_buf (path, "/sys/class/net/%s/tun_flags", ifname);
+	flags = nm_platform_sysctl_get_int_checked (self, NMP_SYSCTL_PATHID_NETDIR (dirfd, ifname, "tun_flags"), 16, 0, G_MAXINT64, -1);
-	val = nm_platform_sysctl_get (self, NMP_SYSCTL_PATHID_ABSOLUTE (path));
+	if (flags >= 0) {
-	if (val) {
-		gint64 flags;
-
-		flags = _nm_utils_ascii_str_to_int64 (val, 16, 0, G_MAXINT64, 0);
-		if (!errno) {
 		props->mode = ((flags & (IFF_TUN | IFF_TAP)) == IFF_TUN) ? "tun" : "tap";
 		props->no_pi = !!(flags & IFF_NO_PI);
 		props->vnet_hdr = !!(flags & IFF_VNET_HDR);
 		props->multi_queue = !!(flags & NM_IFF_MULTI_QUEUE);
 	} else
 		success = FALSE;
-		g_free (val);
-	} else
-		success = FALSE;
 
 	return success;
 }
 
-gboolean
-nm_platform_link_tun_get_properties (NMPlatform *self, int ifindex, NMPlatformTunProperties *props)
-{
-	_CHECK_SELF (self, klass, FALSE);
-
-	g_return_val_if_fail (ifindex > 0, FALSE);
-	g_return_val_if_fail (props != NULL, FALSE);
-
-	return nm_platform_link_tun_get_properties_ifname (self, nm_platform_link_get_name (self, ifindex), props);
-}
-
 gboolean
 nm_platform_wifi_get_capabilities (NMPlatform *self, int ifindex, NMDeviceWifiCapabilities *caps)
 {

src/platform/nm-platform.h

@@ -865,9 +865,7 @@ NMPlatformError nm_platform_link_infiniband_delete (NMPlatform *self,
 gboolean nm_platform_link_infiniband_get_properties (NMPlatform *self, int ifindex, int *parent, int *p_key, const char **mode);
 
 gboolean nm_platform_link_veth_get_properties   (NMPlatform *self, int ifindex, int *out_peer_ifindex);
-gboolean nm_platform_link_tun_get_properties    (NMPlatform *self, int ifindex, NMPlatformTunProperties *properties);
+gboolean nm_platform_link_tun_get_properties    (NMPlatform *self, int ifindex, const char *ifname_guess, NMPlatformTunProperties *properties);
-
-gboolean nm_platform_link_tun_get_properties_ifname (NMPlatform *platform, const char *ifname, NMPlatformTunProperties *props);
 
 gboolean    nm_platform_wifi_get_capabilities (NMPlatform *self, int ifindex, NMDeviceWifiCapabilities *caps);
 gboolean    nm_platform_wifi_get_bssid        (NMPlatform *self, int ifindex, guint8 *bssid);