diff --git a/src/NetworkManagerUtils.c b/src/NetworkManagerUtils.c
index b2d98ca58d..deab2a5869 100644
--- a/src/NetworkManagerUtils.c
+++ b/src/NetworkManagerUtils.c
@@ -1749,6 +1749,121 @@ nm_utils_to_string_buffer_init_null (gconstpointer obj, char **buf, gsize *len)
 	return TRUE;
 }
 
+void
+nm_utils_strbuf_append_c (char **buf, gsize *len, char c)
+{
+	switch (*len) {
+	case 0:
+		return;
+	case 1:
+		(*buf)[0] = '\0';
+		*len = 0;
+		(*buf)++;
+		return;
+	default:
+		(*buf)[0] = c;
+		(*buf)[1] = '\0';
+		(*len)--;
+		(*buf)++;
+		return;
+	}
+}
+
+void
+nm_utils_strbuf_append_str (char **buf, gsize *len, const char *str)
+{
+	gsize src_len;
+
+	switch (*len) {
+	case 0:
+		return;
+	case 1:
+		if (!str || !*str) {
+			(*buf)[0] = '\0';
+			return;
+		}
+		(*buf)[0] = '\0';
+		*len = 0;
+		(*buf)++;
+		return;
+	default:
+		if (!str || !*str) {
+			(*buf)[0] = '\0';
+			return;
+		}
+		src_len = g_strlcpy (*buf, str, *len);
+		if (src_len >= *len) {
+			*buf = &(*buf)[*len];
+			*len = 0;
+		} else {
+			*buf = &(*buf)[src_len];
+			*len -= src_len;
+		}
+		return;
+	}
+}
+
+void
+nm_utils_strbuf_append (char **buf, gsize *len, const char *format, ...)
+{
+	char *p = *buf;
+	va_list args;
+	gint retval;
+
+	if (*len == 0)
+		return;
+
+	va_start (args, format);
+	retval = g_vsnprintf (p, *len, format, args);
+	va_end (args);
+
+	if (retval >= *len) {
+		*buf = &p[*len];
+		*len = 0;
+	} else {
+		*buf = &p[retval];
+		*len -= retval;
+	}
+}
+
+const char *
+nm_utils_flags2str (const NMUtilsFlags2StrDesc *descs,
+                    gsize n_descs,
+                    unsigned flags,
+                    char *buf,
+                    gsize len)
+{
+	gsize i;
+	char *p;
+
+	nm_utils_to_string_buffer_init (&buf, &len);
+
+	if (!len)
+		return buf;
+
+	buf[0] = '\0';
+	if (!flags) {
+		return buf;
+	}
+
+	p = buf;
+	for (i = 0; flags && i < n_descs; i++) {
+		if (NM_FLAGS_HAS (flags, descs[i].flag)) {
+			flags &= ~descs[i].flag;
+
+			if (buf[0] != '\0')
+				nm_utils_strbuf_append_c (&p, &len, ',');
+			nm_utils_strbuf_append_str (&p, &len, descs[i].name);
+		}
+	}
+	if (flags) {
+		if (buf[0] != '\0')
+			nm_utils_strbuf_append_c (&p, &len, ',');
+		nm_utils_strbuf_append (&p, &len, "0x%x", flags);
+	}
+	return buf;
+};
+
 /*****************************************************************************/
 
 /**
diff --git a/src/NetworkManagerUtils.h b/src/NetworkManagerUtils.h
index b4cc180013..3da2235559 100644
--- a/src/NetworkManagerUtils.h
+++ b/src/NetworkManagerUtils.h
@@ -196,6 +196,23 @@ extern char _nm_utils_to_string_buffer[2096];
 void     nm_utils_to_string_buffer_init (char **buf, gsize *len);
 gboolean nm_utils_to_string_buffer_init_null (gconstpointer obj, char **buf, gsize *len);
 
+typedef struct {
+	unsigned flag;
+	const char *name;
+} NMUtilsFlags2StrDesc;
+
+#define NM_UTILS_FLAGS2STR(f, n) { .flag = f, .name = ""n, }
+
+const char *nm_utils_flags2str (const NMUtilsFlags2StrDesc *descs,
+                                gsize n_descs,
+                                unsigned flags,
+                                char *buf,
+                                gsize len);
+
+void nm_utils_strbuf_append (char **buf, gsize *len, const char *format, ...) __attribute__((__format__ (__printf__, 3, 4)));
+void nm_utils_strbuf_append_c (char **buf, gsize *len, char c);
+void nm_utils_strbuf_append_str (char **buf, gsize *len, const char *str);
+
 const char *nm_utils_get_shared_wifi_permission (NMConnection *connection);
 
 const char *nm_utils_get_ip_config_method (NMConnection *connection,
diff --git a/src/tests/test-general.c b/src/tests/test-general.c
index 3985d23ebe..2eb524c3b4 100644
--- a/src/tests/test-general.c
+++ b/src/tests/test-general.c
@@ -971,6 +971,116 @@ test_nm_match_spec_match_config (void)
 
 /*******************************************/
 
+static void
+test_nm_utils_strbuf_append (void)
+{
+#define BUF_ORIG "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+#define STR_ORIG "abcdefghijklmnopqrstuvwxyz"
+	int buf_len;
+	int rep;
+	char buf[STRLEN (BUF_ORIG) + 1];
+	char str[STRLEN (BUF_ORIG) + 1];
+
+	for (buf_len = 0; buf_len < 10; buf_len++) {
+		for (rep = 0; rep < 50; rep++) {
+			const int s_len = nmtst_get_rand_int () % (sizeof (str) - 5);
+			char *t_buf;
+			gsize t_len;
+			int test_mode;
+
+			strcpy (str, STR_ORIG);
+			str[s_len] = '\0';
+
+			g_assert_cmpint (str[sizeof (str) - 1], ==, '\0');
+			g_assert_cmpint (strlen (str), ==, s_len);
+
+			strcpy (buf, BUF_ORIG);
+
+			t_buf = buf;
+			t_len = buf_len;
+
+			test_mode = nmtst_get_rand_int () % 4;
+
+			switch (test_mode) {
+			case 0:
+				if (s_len == 1) {
+					nm_utils_strbuf_append_c (&t_buf, &t_len, str[0]);
+					break;
+				}
+				/* fall-through */
+			case 1:
+				nm_utils_strbuf_append_str (&t_buf, &t_len, str);
+				break;
+			case 2:
+				if (s_len == 1) {
+					nm_utils_strbuf_append (&t_buf, &t_len, "%c", str[0]);
+					break;
+				}
+				/* fall-through */
+			case 3:
+				nm_utils_strbuf_append (&t_buf, &t_len, "%s", str);
+				break;
+			}
+
+			/* Assert that the source-buffer is unmodified. */
+			g_assert_cmpint (str[s_len], ==, '\0');
+			str[s_len] = STR_ORIG[s_len];
+			g_assert (!memcmp (str, STR_ORIG, sizeof (str)));
+			str[s_len] = '\0';
+
+			g_assert_cmpint (t_len, >=, 0);
+			g_assert_cmpint (t_len, <=, buf_len);
+			g_assert (t_buf >= buf);
+
+			/* Assert what was written to the destination buffer. */
+			switch (buf_len) {
+			case 0:
+				g_assert_cmpint (t_len, ==, 0);
+				g_assert (t_buf == buf);
+				g_assert (!memcmp (buf, BUF_ORIG, sizeof (buf)));
+				break;
+			case 1:
+				if (s_len == 0) {
+					g_assert_cmpint (t_len, ==, 1);
+					g_assert (t_buf == buf);
+					g_assert (buf[0] == '\0');
+					g_assert (!memcmp (&buf[1], &BUF_ORIG[1], sizeof (buf) - 1));
+				} else {
+					g_assert_cmpint (t_len, ==, 0);
+					g_assert (t_buf == &buf[1]);
+					g_assert (buf[0] == '\0');
+					g_assert (!memcmp (&buf[1], &BUF_ORIG[1], sizeof (buf) - 1));
+				}
+				break;
+			default:
+				if (s_len == 0) {
+					g_assert_cmpint (t_len, ==, buf_len);
+					g_assert (t_buf == buf);
+					g_assert (buf[0] == '\0');
+					g_assert (!memcmp (&buf[1], &BUF_ORIG[1], sizeof (buf) - 1));
+				} else if (buf_len <= s_len) {
+					g_assert_cmpint (t_len, ==, 0);
+					g_assert (t_buf == &buf[buf_len]);
+					g_assert (!memcmp (buf, STR_ORIG, buf_len - 1));
+					g_assert (buf[buf_len - 1] == '\0');
+					g_assert (!memcmp (&buf[buf_len], &BUF_ORIG[buf_len], sizeof (buf) - buf_len));
+				} else {
+					g_assert_cmpint (t_len, >, 0);
+					g_assert_cmpint (buf_len - t_len, ==, s_len);
+					g_assert_cmpint (strlen (buf), ==, s_len);
+					g_assert (t_buf == &buf[s_len]);
+					g_assert (!memcmp (buf, STR_ORIG, s_len));
+					g_assert (buf[s_len] == '\0');
+					g_assert (!memcmp (&buf[s_len + 1], &BUF_ORIG[s_len + 1], sizeof (buf) - s_len - 1));
+				}
+				break;
+			}
+		}
+	}
+}
+
+/*******************************************/
+
 NMTST_DEFINE ();
 
 int
@@ -978,6 +1088,8 @@ main (int argc, char **argv)
 {
 	nmtst_init_with_logging (&argc, &argv, NULL, "ALL");
 
+	g_test_add_func ("/general/nm_utils_strbuf_append", test_nm_utils_strbuf_append);
+
 	g_test_add_func ("/general/nm_utils_ip6_address_clear_host_address", test_nm_utils_ip6_address_clear_host_address);
 	g_test_add_func ("/general/nm_utils_log_connection_diff", test_nm_utils_log_connection_diff);