+#define SUB_DELIM_CHARS "!$&'()*+,;="
+
+static gboolean
+is_valid (char c,
+ const char *reserved_chars_allowed)
+{
+ if (g_ascii_isalnum (c) ||
+ c == '-' ||
+ c == '.' ||
+ c == '_' ||
+ c == '~')
+ return TRUE;
+
+ if (reserved_chars_allowed &&
+ strchr (reserved_chars_allowed, c) != NULL)
+ return TRUE;
+
+ return FALSE;
+}
+
+static gboolean
+gunichar_ok (gunichar c)
+{
+ return
+ (c != (gunichar) -2) &&
+ (c != (gunichar) -1);
+}
+
+/**
+ * g_string_append_uri_escaped:
+ * @string: a #GString
+ * @unescaped: a string
+ * @reserved_chars_allowed: a string of reserved characters allowed
+ * to be used, or %NULL
+ * @allow_utf8: set %TRUE if the escaped string may include UTF8 characters
+ *
+ * Appends @unescaped to @string, escaped any characters that
+ * are reserved in URIs using URI-style escape sequences.
+ *
+ * Returns: @string
+ *
+ * Since: 2.16
+ */
+GString *
+g_string_append_uri_escaped (GString *string,
+ const gchar *unescaped,
+ const gchar *reserved_chars_allowed,
+ gboolean allow_utf8)
+{
+ unsigned char c;
+ const gchar *end;
+ static const gchar hex[16] = "0123456789ABCDEF";
+
+ g_return_val_if_fail (string != NULL, NULL);
+ g_return_val_if_fail (unescaped != NULL, NULL);
+
+ end = unescaped + strlen (unescaped);
+
+ while ((c = *unescaped) != 0)
+ {
+ if (c >= 0x80 && allow_utf8 &&
+ gunichar_ok (g_utf8_get_char_validated (unescaped, end - unescaped)))
+ {
+ int len = g_utf8_skip [c];
+ g_string_append_len (string, unescaped, len);
+ unescaped += len;
+ }
+ else if (is_valid (c, reserved_chars_allowed))
+ {
+ g_string_append_c (string, c);
+ unescaped++;
+ }
+ else
+ {
+ g_string_append_c (string, '%');
+ g_string_append_c (string, hex[((guchar)c) >> 4]);
+ g_string_append_c (string, hex[((guchar)c) & 0xf]);
+ unescaped++;
+ }
+ }
+
+ return string;
+}
+
+/**
+ * g_string_append:
+ * @string: a #GString
+ * @val: the string to append onto the end of @string
+ *
+ * Adds a string onto the end of a #GString, expanding
+ * it if necessary.
+ *
+ * Returns: @string
+ */
+GString *