core: add nm_utils_machine_id_read() and parse() util

src/Makefile.am

@@ -209,6 +209,7 @@ libNetworkManager_base_la_CPPFLAGS = \
 	-DNETWORKMANAGER_COMPILATION=NM_NETWORKMANAGER_COMPILATION_INSIDE_DAEMON \
 	-DNO_SYSTEMD_JOURNAL \
 	-DPREFIX=\"$(prefix)\" \
+	-DLOCALSTATEDIR=\"$(localstatedir)\" \
 	-DNMSTATEDIR=\"$(nmstatedir)\" \
 	$(GLIB_CFLAGS)
 

src/nm-core-utils.c

@@ -2588,6 +2588,64 @@ nm_utils_is_specific_hostname (const char *name)
 
 /******************************************************************/
 
+gboolean
+nm_utils_machine_id_parse (const char *id_str, /*uuid_t*/ guchar *out_uuid)
+{
+	int i;
+	guint8 v0, v1;
+
+	if (!id_str)
+		return FALSE;
+
+	for (i = 0; i < 32; i++) {
+		if (!g_ascii_isxdigit (id_str[i]))
+			return FALSE;
+	}
+	if (id_str[i] != '\0')
+		return FALSE;
+
+	if (out_uuid) {
+		for (i = 0; i < 16; i++) {
+			v0 = g_ascii_xdigit_value (*(id_str++));
+			v1 = g_ascii_xdigit_value (*(id_str++));
+			out_uuid[i] = (v0 << 4) + v1;
+		}
+	}
+	return TRUE;
+}
+
+char *
+nm_utils_machine_id_read (void)
+{
+	gs_free char *contents = NULL;
+	int i;
+
+	/* Get the machine ID from /etc/machine-id; it's always in /etc no matter
+	 * where our configured SYSCONFDIR is.  Alternatively, it might be in
+	 * LOCALSTATEDIR /lib/dbus/machine-id.
+	 */
+	if (   !g_file_get_contents ("/etc/machine-id", &contents, NULL, NULL)
+	    && !g_file_get_contents (LOCALSTATEDIR "/lib/dbus/machine-id", &contents, NULL, NULL))
+		return FALSE;
+
+	contents = g_strstrip (contents);
+
+	for (i = 0; i < 32; i++) {
+		if (!g_ascii_isxdigit (contents[i]))
+			return FALSE;
+		if (contents[i] >= 'A' && contents[i] <= 'F') {
+			/* canonicalize to lower-case */
+			contents[i] = 'a' + (contents[i] - 'A');
+		}
+	}
+	if (contents[i] != '\0')
+		return FALSE;
+
+	return nm_unauto (&contents);
+}
+
+/*****************************************************************************/
+
 guint8 *
 nm_utils_secret_key_read (gsize *out_key_len, GError **error)
 {

src/nm-core-utils.h

@@ -307,6 +307,9 @@ const char *nm_utils_ip4_property_path (const char *ifname, const char *property
 
 gboolean nm_utils_is_specific_hostname (const char *name);
 
+char *nm_utils_machine_id_read (void);
+gboolean nm_utils_machine_id_parse (const char *id_str, /*uuid_t*/ guchar *out_uuid);
+
 guint8 *nm_utils_secret_key_read (gsize *out_key_len, GError **error);
 
 /* IPv6 Interface Identifer helpers */

src/tests/Makefile.am

@@ -142,6 +142,7 @@ test_utils_DEPENDENCIES = \
 test_utils_CPPFLAGS = \
 	$(AM_CPPFLAGS) \
 	-DPREFIX=\"/nonexistent\" \
+	-DLOCALSTATEDIR=\"$(localstatedir)\" \
 	-DNMSTATEDIR=\"/nonsense\"
 
 test_utils_LDADD = \