The function reads resource content into a buffer whose size matches the
size of the file contents. This buffer does not have an extra byte that
would 0 terminate this string. This is by itself is not a problem.
Unfortunately the buffer is passed to g_utf8_make_valid function with
size argument specified as -1 which means the buffer is supposed to be
NULL terminated. The end result is g_utf8_make_valid will read at least
1 byte past "contents" buffer size.
Fix this by specifying buffer size when calling g_utf8_make_valid.
f86bbb09f8