shared: add nm_json_aux_gstr_append_*() helper

shared/nm-glib-aux/nm-json-aux.c

@@ -20,3 +20,130 @@
 #include "nm-default.h"
 
 #include "nm-json-aux.h"
+
+/*****************************************************************************/
+
+static void
+_gstr_append_string_len (GString *gstr,
+                         const char *str,
+                         gsize len)
+{
+	g_string_append_c (gstr, '\"');
+
+	while (len > 0) {
+		gsize n;
+		const char *end;
+		gboolean valid;
+
+		nm_assert (len > 0);
+
+		valid = g_utf8_validate (str, len, &end);
+
+		nm_assert (   end
+		           && end >= str
+		           && end <= &str[len]);
+
+		if (end > str) {
+			const char *s;
+
+			for (s = str; s < end; s++) {
+				nm_assert (s[0] != '\0');
+
+				if (s[0] < 0x20) {
+					const char *text;
+
+					switch (s[0]) {
+					case '\\': text = "\\\\"; break;
+					case '\"': text = "\\\""; break;
+					case '\b': text = "\\b";  break;
+					case '\f': text = "\\f";  break;
+					case '\n': text = "\\n";  break;
+					case '\r': text = "\\r";  break;
+					case '\t': text = "\\t";  break;
+					default:
+						g_string_append_printf (gstr, "\\u%04X", (guint) s[0]);
+						continue;
+					}
+					g_string_append (gstr, text);
+					continue;
+				}
+
+				if (NM_IN_SET (s[0], '\\', '\"'))
+					g_string_append_c (gstr, '\\');
+				g_string_append_c (gstr, s[0]);
+			}
+		} else
+			nm_assert (!valid);
+
+		if (valid) {
+			nm_assert (end == &str[len]);
+			break;
+		}
+
+		nm_assert (end < &str[len]);
+
+		if (end[0] == '\0') {
+			/* there is a NUL byte in the string. Technically this is valid UTF-8, so we
+			 * encode it there. However, this will likely result in a truncated string when
+			 * parsing. */
+			g_string_append (gstr, "\\u0000");
+		} else {
+			/* the character is not valid UTF-8. There is nothing we can do about it, because
+			 * JSON can only contain UTF-8 and even the escape sequences can only escape Unicode
+			 * codepoints (but not binary).
+			 *
+			 * The argument is not a a string (in any known encoding), hence we cannot represent
+			 * it as a JSON string (which are unicode strings).
+			 *
+			 * Print an underscore instead of the invalid char :) */
+			g_string_append_c (gstr, '_');
+		}
+
+		n = str - end;
+		nm_assert (n < len);
+		n++;
+		str += n;
+		len -= n;
+	}
+
+	g_string_append_c (gstr, '\"');
+}
+
+void
+nm_json_aux_gstr_append_string_len (GString *gstr,
+                                    const char *str,
+                                    gsize n)
+{
+	g_return_if_fail (gstr);
+
+	_gstr_append_string_len (gstr, str, n);
+}
+
+void
+nm_json_aux_gstr_append_string (GString *gstr,
+                                const char *str)
+{
+	g_return_if_fail (gstr);
+
+	if (!str)
+		g_string_append (gstr, "null");
+	else
+		_gstr_append_string_len (gstr, str, strlen (str));
+}
+
+void
+nm_json_aux_gstr_append_obj_name (GString *gstr,
+                                  const char *key,
+                                  char start_container)
+{
+	g_return_if_fail (gstr);
+	g_return_if_fail (key);
+
+	nm_json_aux_gstr_append_string (gstr, key);
+
+	if (start_container != '\0') {
+		nm_assert (NM_IN_SET (start_container, '[', '{'));
+		g_string_append_printf (gstr, ": %c ", start_container);
+	} else
+		g_string_append (gstr, ": ");
+}

shared/nm-glib-aux/nm-json-aux.h

@@ -20,4 +20,40 @@
 #ifndef __NM_JSON_AUX_H__
 #define __NM_JSON_AUX_H__
 
+/*****************************************************************************/
+
+static inline GString *
+nm_json_aux_gstr_append_delimiter (GString *gstr)
+{
+	g_string_append (gstr, ", ");
+	return gstr;
+}
+
+void nm_json_aux_gstr_append_string_len (GString *gstr,
+                                         const char *str,
+                                         gsize n);
+
+void nm_json_aux_gstr_append_string (GString *gstr,
+                                     const char *str);
+
+static inline void
+nm_json_aux_gstr_append_bool (GString *gstr,
+                              gboolean v)
+{
+	g_string_append (gstr, v ? "true" : "false");
+}
+
+static inline void
+nm_json_aux_gstr_append_int64 (GString *gstr,
+                               gint64 v)
+{
+	g_string_append_printf (gstr, "%"G_GINT64_FORMAT, v);
+}
+
+void nm_json_aux_gstr_append_obj_name (GString *gstr,
+                                       const char *key,
+                                       char start_container);
+
+/*****************************************************************************/
+
 #endif  /* __NM_JSON_AUX_H__ */