core: add nm_utils_sysctl_ip_conf_is_path() util

src/nm-core-utils.c

@@ -2547,7 +2547,7 @@ nm_utils_sysctl_ip_conf_path (int addr_family, char *buf, const char *ifname, co
 	nm_assert (buf);
 	nm_assert_addr_family (addr_family);
 
-	ifname = NM_ASSERT_VALID_PATH_COMPONENT (ifname);
+	g_assert (nm_utils_is_valid_iface_name (ifname, NULL));
 	property = NM_ASSERT_VALID_PATH_COMPONENT (property);
 
 	len = g_snprintf (buf,
@@ -2560,6 +2560,55 @@ nm_utils_sysctl_ip_conf_path (int addr_family, char *buf, const char *ifname, co
 	return buf;
 }
 
+gboolean
+nm_utils_sysctl_ip_conf_is_path (int addr_family, const char *path, const char *ifname, const char *property)
+{
+	g_return_val_if_fail (path, FALSE);
+	NM_ASSERT_VALID_PATH_COMPONENT (property);
+	g_assert (!ifname || nm_utils_is_valid_iface_name (ifname, NULL));
+
+	if (addr_family == AF_INET) {
+		if (!g_str_has_prefix (path, IPV4_PROPERTY_DIR))
+			return FALSE;
+		path += NM_STRLEN (IPV4_PROPERTY_DIR);
+	} else if (addr_family == AF_INET6) {
+		if (!g_str_has_prefix (path, IPV6_PROPERTY_DIR))
+			return FALSE;
+		path += NM_STRLEN (IPV6_PROPERTY_DIR);
+	} else
+		g_return_val_if_reached (FALSE);
+
+	if (ifname) {
+		if (!g_str_has_prefix (path, ifname))
+			return FALSE;
+		path += strlen (ifname);
+		if (path[0] != '/')
+			return FALSE;
+		path++;
+	} else {
+		const char *slash;
+		char buf[IFNAMSIZ];
+		gsize l;
+
+		slash = strchr (path, '/');
+		if (!slash)
+			return FALSE;
+		l = slash - path;
+		if (l >= IFNAMSIZ)
+			return FALSE;
+		memcpy (buf, path, l);
+		buf[l] = '\0';
+		if (!nm_utils_is_valid_iface_name (buf, NULL))
+			return FALSE;
+		path = slash + 1;
+	}
+
+	if (!nm_streq (path, property))
+		return FALSE;
+
+	return TRUE;
+}
+
 gboolean
 nm_utils_is_valid_path_component (const char *name)
 {

src/nm-core-utils.h

@@ -253,6 +253,8 @@ const char *NM_ASSERT_VALID_PATH_COMPONENT (const char *name);
 
 const char *nm_utils_sysctl_ip_conf_path (int addr_family, char *buf, const char *ifname, const char *property);
 
+gboolean nm_utils_sysctl_ip_conf_is_path (int addr_family, const char *path, const char *ifname, const char *property);
+
 gboolean nm_utils_is_specific_hostname (const char *name);
 
 int nm_utils_fd_get_contents (int fd,

src/tests/test-general.c

@@ -272,6 +272,32 @@ test_nm_utils_log_connection_diff (void)
 
 /*****************************************************************************/
 
+static void
+do_test_sysctl_ip_conf (int addr_family,
+                        const char *iface,
+                        const char *property)
+{
+	char path[NM_UTILS_SYSCTL_IP_CONF_PATH_BUFSIZE];
+	const char *pp;
+
+	pp = nm_utils_sysctl_ip_conf_path (addr_family, path, iface, property);
+	g_assert (pp == path);
+	g_assert (path[0] == '/');
+
+	g_assert (nm_utils_sysctl_ip_conf_is_path (addr_family, path, iface, property));
+	g_assert (nm_utils_sysctl_ip_conf_is_path (addr_family, path, NULL, property));
+}
+
+static void
+test_nm_utils_sysctl_ip_conf_path (void)
+{
+	do_test_sysctl_ip_conf (AF_INET6, "a", "mtu");
+	do_test_sysctl_ip_conf (AF_INET6, "eth0", "mtu");
+	do_test_sysctl_ip_conf (AF_INET6, "e23456789012345", "mtu");
+}
+
+/*****************************************************************************/
+
 static NMConnection *
 _match_connection_new (void)
 {
@@ -1716,6 +1742,8 @@ main (int argc, char **argv)
 	g_test_add_func ("/general/nm_utils_ip6_address_same_prefix", test_nm_utils_ip6_address_same_prefix);
 	g_test_add_func ("/general/nm_utils_log_connection_diff", test_nm_utils_log_connection_diff);
 
+	g_test_add_func ("/general/nm_utils_sysctl_ip_conf_path", test_nm_utils_sysctl_ip_conf_path);
+
 	g_test_add_func ("/general/exp10", test_nm_utils_exp10);
 
 	g_test_add_func ("/general/connection-match/basic", test_connection_match_basic);