* 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 PR fixes an incorrect comparison in figuring out `minChain` in
`ZSTD_dedicatedDictSearch_lazy_loadDictionary()`. This incorrect comparison
had been masked by the fact that `idx` was always 1, until @terrelln changed
that in #2726.
Credit-to: OSS-Fuzz
The DUBT can be non-deterministic if an index is equal to
`ZSTD_DUBT_UNSORTED_MARK`. Ensure that never happens by starting the
indices at 2.
This bug was found by the OSS-Fuzz determinism fuzzer. With this change
the fuzzer test passes. And I've confirmed that this is the root cause,
not just hiding the problem.
Aside: This took me a long time to figure out, because I thought I had
tried this first thing. But, apparantly I messed it up, because when I
was going through it again with @felixhandte, I was pointing out that it
wasn't the case, but it turns out it was.
Credit to: OSS-Fuzz
Add the libzstd.pc target to the lib target in lib/Makefile, which makes
it inherit LDFLAGS_DYNLIB from the lib-mt target. This allows us to add
a Libs.private field to libzstd.pc which gets conditionally populated
with '-pthread'.
The 1.5.0 release notes mention that the static library isn't
multi-threaded by default, due to concern for people building static
binaries with libzstd:
Now the dynamic library supports multi-threaded compression by
default. Note that this property is not extended to the static
library because doing so would have impacted the build script of
existing client applications (requiring them to add -pthread to their
recipe), thus potentially breaking their build.
To get closer to being able to enable multi-threading for all library
builds by default, this commit makes it so that any libzstd consumer
using pkg-config gets the correct flags.
We also fix the indentation of the rule for libzstd.pc and move it
outside the if/endif block for install rules (which uses a list of OSs
where the rules were validated), so the rule is available for all users
of the 'lib*' targets.
* The block splitter missed a bounds check, so when the buffer is too small it
passes an erroneously large size to `ZSTD_entropyCompressSeqStore()`, which
can then write the compressed data past the end of the buffer. This is a new
regression in v1.5.0 when the block splitter is enabled. It is either enabled
explicitly, or implicitly when using the optimal parser and `ZSTD_compress2()`
or `ZSTD_compressStream*()`.
* `HUF_writeCTable_wksp()` omits a bounds check when calling
`HUF_compressWeights()`. If it is called with `dstCapacity == 0` it will pass
an erroneously large size to `HUF_compressWeights()`, which can then write
past the end of the buffer. This bug has been present for ages. However, I
believe that zstd cannot trigger the bug, because it never calls
`HUF_compress*()` with `dstCapacity == 0` because of [this check][1].
Credit to: Oss-Fuzz
[1]: https://github.com/facebook/zstd/blob/89127e5ee2f3c1e141668fa6d4ee91245f05d132/lib/compress/zstd_compress_literals.c#L100
