In zstd 1.3.0, once you have called ZSTD_endStream and been told
that your putput buffer is full, it really doesn't want you to call
ZSTD_compressStream again. ZSTD 1.2.0 didn't seem to mind about
this.
This patch fixes the issue by making sure never to call
ZSTD_endStream if there's any more data on the input buffer to
process, by flushing even when we're about to call "endStream", and
by never calling "compress" or "flush" after "endStream".
This patch adds support for measuring the approximated memory usage by
the individual `tor_zstd_compress_state_t` object instances.
See: https://bugs.torproject.org/22066
Since we have a streaming API for each compression backend, we don't
need a non-streaming API for each: we can build a common
non-streaming API at the front-end.
This patch splits up `tor_compress_memory_level()` into static functions
in the individual compression backends, which allows us to tune the
values per compression backend rather than globally.
See: https://bugs.torproject.org/21662
This patch adds `tor_compress_version_str()` and
`tor_compress_header_version_str()` to get the version strings of the
different compression schema providers. Both functions returns `NULL` in
case a given `compress_method_t` is unknown or unsupported.
See: https://bugs.torproject.org/21662
This patch adds support for checking if a given `compress_method_t` is
supported by the currently running Tor instance using
`tor_compress_supports_method()`.
See: https://bugs.torproject.org/21662
