valgrind spotted this one: a read off the end of the `stop_chars` buffer
when `stop_chars_len == -1`, due to the fuzzing test not sticking to the
requirement from `g_data_input_stream_read_upto()` that `stop_chars`
must be nul-terminated if `stop_chars_len < 0`.
This can happen when reading `fuzzing/README.md`, which is done as a
smoketest when the fuzzing tests are run without the fuzzer, as normal
unit tests. In this case, it made smoke.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
While reading a single byte or uint16 from an input stream is fairly
simple and uncontroversial, the code to read a line or read up to any of
a set of stop characters is not so trivial. People may be using
`GDataInputStream` to parse untrusted input like this, so we should
probably test that it’s robust against a variety of input conditions.
Signed-off-by: Philip Withnall <pwithnall@gnome.org>
