commit 2ae51ed5e20ee045251d9d6ddf12755bca7c9c8c Author: Nick Mathewson nickm@torproject.org Date: Fri Jul 14 16:21:51 2017 -0400
Fix zstd 1.3.0 trouble: Be more respectful of its state machine
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". --- changes/bug22927 | 6 ++++++ src/common/compress_zstd.c | 29 +++++++++++++++++++++++------ 2 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/changes/bug22927 b/changes/bug22927 new file mode 100644 index 000000000..6e68e6ff0 --- /dev/null +++ b/changes/bug22927 @@ -0,0 +1,6 @@ + o Minor bugfixes (compatibility, zstd): + - Write zstd epilogues correctly when the epilogue requires reallocation + of the output buffer, even with zstd 1.3.0. (Previously, + we worked on 1.2.0 and failed with 1.3.0). Fixes bug 22927; bugfix on + 0.3.1.1-alpha. + diff --git a/src/common/compress_zstd.c b/src/common/compress_zstd.c index a136db48b..94974dec0 100644 --- a/src/common/compress_zstd.c +++ b/src/common/compress_zstd.c @@ -98,6 +98,8 @@ struct tor_zstd_compress_state_t { #endif // HAVE_ZSTD.
int compress; /**< True if we are compressing; false if we are inflating */ + int have_called_end; /**< True if we are compressing and we've called + * ZSTD_endStream */
/** Number of bytes read so far. Used to detect compression bombs. */ size_t input_so_far; @@ -270,9 +272,16 @@ tor_zstd_compress_process(tor_zstd_compress_state_t *state, ZSTD_inBuffer input = { *in, *in_len, 0 }; ZSTD_outBuffer output = { *out, *out_len, 0 };
+ if (BUG(finish == 0 && state->have_called_end)) { + finish = 1; + } + if (state->compress) { - retval = ZSTD_compressStream(state->u.compress_stream, - &output, &input); + if (! state->have_called_end) + retval = ZSTD_compressStream(state->u.compress_stream, + &output, &input); + else + retval = 0; } else { retval = ZSTD_decompressStream(state->u.decompress_stream, &output, &input); @@ -300,7 +309,7 @@ tor_zstd_compress_process(tor_zstd_compress_state_t *state, return TOR_COMPRESS_ERROR; }
- if (state->compress && !finish) { + if (state->compress && !state->have_called_end) { retval = ZSTD_flushStream(state->u.compress_stream, &output);
*out = (char *)output.dst + output.pos; @@ -314,16 +323,24 @@ tor_zstd_compress_process(tor_zstd_compress_state_t *state,
// ZSTD_flushStream returns 0 if the frame is done, or >0 if it // is incomplete. - if (retval > 0) + if (retval > 0) { return TOR_COMPRESS_BUFFER_FULL; + } }
if (!finish) { - // We're not done with the input, so no need to flush. + // The caller says we're not done with the input, so no need to write an + // epilogue. return TOR_COMPRESS_OK; } else if (state->compress) { - retval = ZSTD_endStream(state->u.compress_stream, &output); + if (*in_len) { + // We say that we're not done with the input, so we can't write an + // epilogue. + return TOR_COMPRESS_OK; + }
+ retval = ZSTD_endStream(state->u.compress_stream, &output); + state->have_called_end = 1; *out = (char *)output.dst + output.pos; *out_len = output.size - output.pos;