* Add a Huffman round trip fuzzer
* Fix two minor bugs in Huffman that aren't exposed in zstd
- Incorrect weight comparison (weights are allowed to be equal to
table log).
- HUF_compress1X_usingCTable_internal() can return compressed
size >= source size, so the assert that `cSize <= 65535` isn't
correct, and it needs to be checked instead.
This patch is supposed to improve compatibility with less featured tar variants
"when the tar program used does not support historical options (without hyphen) nor the '-z' option."
Patch proposed by Antonio Diaz Diaz
Compress the input twice in the `simple_round_trip` and
`dictionary_round_trip` fuzzers with exactly the same parameters, but
reusing the context. Then ensure that the compressed output is
identical.
This flag forces zstd to always load the prefix in ext-dict mode, even
if it happens to be contiguous, to force determinism. It also applies to
dictionaries that are re-processed.
A determinism test case is also added, which fails without
`ZSTD_c_deterministicRefPrefix` and passes with it set.
Question: Should this be the default behavior? It isn't in this PR.
`open()`'s mode bits are only applied to files that are created by the call.
If the output file already exists, but is not readable, the `fopen()` would
fail, preventing us from removing it, which would mean that the file would
not end up with the correct permission bits.
It's not clear to me why the `fopen()` is there at all. `UTIL_isRegularFile()`
should be sufficient, AFAICT.
previous lower limit was 1 MB.
Note : by default, the lowest job size is 2 MB, achieved at level 1.
Even lower job sizes can be achieved by manipulating this value directly,
or manually modifying window sizes to lower amounts.
Updated unit test to ensure that this new limit works fine
(test would fail with previous 1 MB limit).
Switch from `-T0` to the default `-T1` which significantly reduces
memory usage for level 19 when there are many cores. This fixes
32-bit issues of running out of address space.
Fixes#2603.
* Fix overflow correction when `windowLog < cycleLog`. Previously, we
got the correction wrong in this case, and our chain tables and binary
trees would be corrupted. Now, we work as long as `maxDist` is a power
of two, by adding `MAX(maxDist, cycleSize)` to our indices.
* When `ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY` is defined to non-zero
run overflow correction as frequently as allowed without impacting
compression ratio.
* Enable `ZSTD_WINDOW_OVERFLOW_CORRECT_FREQUENTLY` in `fuzzer` and
`zstreamtest` as well as all the OSS-Fuzz fuzzers. This has a 5-10%
speed penalty at most, which seems reasonable.
W. Felix Handte