This patch restores capability for each file to receive adapted compression parameters depending on its size.
The bug breaking this feature was relatively silly :
setting a parameter with a value "0" is supposed to be a no-op.
Unfortunately, it would pin down compression parameters as if they were manually set,
preventing later automatic adaptation.
Unfortunately, I'm currently short of a test case that could check this situation and trigger an error.
Compression parameters selection between tableID 0,1,2,3 is largely internal,
leaving no trace to outside world, not even in frame header.
Fixes issue where, when `zstd --format=lz4` is fed an input larger than 128KB,
the read overruns the input buffer. This changes Zstd to use LZ4 with chained
64KB blocks. This is technically a breaking change in that some third party
LZ4 implementations may not support linked blocks. However, progress should not
be allowed to be stopped by such petty concerns as backwards compatibility!
we lose a warning message :
when a job size is chosen < minimum job size for multithreading,
it is automatically resized to minimum size.
If this information is really useful, it should be present in zstd.h now.
removed the other 2 code paths (single thread, and ZSTDMT ones)
keeping only the new advanced API, for easier code coverage.
It shall also fix identified issue with Visual Studio
which doesn't have ZSTD_NEWAPI defined.
UTIL_getFileSize() used to return zero on failure.
This made it impossible to distinguish a failure from a genuine empty file.
Both cases where coalesced.
Adding UTIL_FILESIZE_UNKNOWN constant has many consequences on user code,
since in many places, the `0` was assumed to mean "error".
This is no longer the case, and the error code must be actively checked.
It was multiple reasons stacked :
- Visual use a different code path, because ZSTD_NEWAPI is not defined
- fileio.c sends `0` as `pledgedSrcSize` to mean `ZSTD_CONTENTSIZE_UNKNOWN` (fixed)
- ZSTDMT_resetCCtx() interpreted `0` as "empty" instead of "unknown" (fixed)
when determining compression parameters
to compress one file only.
For multiple files, it still "bets" that files are going to be small.
There was also a bug recently added in ZSTD_CCtx_loadDictionary_advanced()
making it incapable to use pledgedSrcSize to determine compression parameters.
It's not good to mix old and new API
ZSTD_resetCStream() doesn't just set pledgedSrcSize :
it also sets the CCtx for a single thread compression.
Problem is, when 2+ threads are defined in cctx->requestedParams,
ZSTD_compress_generic() will want to start MT compression,
since initialization is supposed to have already happened (thanks to ZSTD_resetCStream())
except that the underlying ZSTDMT_CCtx* object is not created,
resulting in a segfault.
This is an invalid construction
(correct one is to use ZSTD_CCtx_setPledgedSrcSize()).
I haven't found a nice way to mitigate this impact if someone makes the same mistake.
At some point, removing the old API to keep only the new API within fileio.c will limit these risks.
srcSize is read and provided at each file, not at resource creation.
This used to be useful with older API, because it could not re-adapt parameters between sessions.
At some point, it will be better to remove the old code, and only keep the new_api.
It works fine by now.
fixes#874 :
when a frame is not properly terminated by a "last block" signal,
zstd -d used to detect it immediately and error out.
This version will decode and flush the last block, and only then issue an error.
* Maximum window size in 32-bit mode is 1GB, since allocations for 2GB fail
on my Mac.
* Maximum window size in 64-bit mode is 2GB, since that is the largest
power of 2 that works with the overflow prevention.
* Allow `--long=windowLog` to set the window log, along with
`--zstd=wlog=#`. These options also set the window size during
decompression, but don't override `--memory=#` if it is set.
* Present a helpful error message when the window size is too large during
decompression.
* The long range matcher defaults to a hash log 7 less than the window log,
which keeps it at 20 for window log 27.
* Keep the default long range matcher window size and the default maximum
window size at 27 for the API and CLI.
* Add tests that use the maximum window size and hash size for compression
and decompression.
Simple makefile change + quick typename change
Test:
make clean
make
# successfully produces binary without lz4 support
make clean
# with flags to pick up my lz4 build
make MOREFLAGS="-L/home/felixh/prog/lz4/lib -I/home/felixh/prog/lz4/lib"
# successfully produces binary with lz4 support
echo "TEST TEST TEST THIS IS A TEST STRING PLEASE TEST THIS PLEASE OK THANK YOU" | \
./lz4/lz4 | \
LD_LIBRARY_PATH=/home/felixh/prog/lz4/lib ./zstd/zstd -d
# successfully prints TEST TEST TEST THIS IS A TEST STRING PLEASE TEST THIS PLEASE OK THANK YOU
