The match length and literal length extra bytes could either
by 2 bytes or 3 bytes in version 0.5. All earlier verions were
always 3 bytes, and later version didn't have dumps.
The bug, introduced by commit 0fd322f812,
was triggered when the last dump was a 2-byte dump, because we didn't
separate that case from a 3-byte dump, and thought we were over-reading.
I've tested this fix with every zstd version < 1.0.0 on the buggy file,
and we are now always successfully decompressing with the right
checksum.
Fixes#1693.
Compiling with clang-8 fails with the following errors:
largeNbDicts.c:562:37: error: implicit conversion turns floating-point
number into integer: 'const double' to 'U64' (aka 'unsigned long')
[-Werror,-Wfloat-conversion]
U64 const dTime_ns = result.nanoSecPerRun;
~~~~~~~~ ~~~~~~~^~~~~~~~~~~~~
zstdcli.c:300:5: error: '@return' command used in a comment that is
not attached to a function or method declaration
[-Werror,-Wdocumentation]
* @return 1 means that cover parameters were correct
~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zstdcli.c:301:5: error: '@return' command used in a comment that is
not attached to a function or method declaration
[-Werror,-Wdocumentation]
* @return 0 in case of malformed parameters
~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This changes the size limit on compressed blocks to match those of the other
block types: they may not be larger than the `Block_Maximum_Decompressed_Size`,
which is the smaller of the `Window_Size` and 128 KB, removing the additional
restriction that had been placed on `Compressed_Block`s, that they be smaller
than the decompressed content they represent.
Several things motivate removing this restriction. On the one hand, this
restriction is not useful for decoders: the decoder must nonetheless be
prepared to accept compressed blocks that are the full
`Block_Maximum_Decompressed_Size`. And on the other, this bound is actually
artificially limiting. If block representations were entirely independent,
a compressed representation of a block that is larger than the contents of the
block would be ipso facto useless, and it would be strictly better to send it
as an `Raw_Block`. However, blocks are not entirely independent, and it can
make sense to pay the cost of encoding custom entropy tables in a block, even
if that pushes that block size over the size of the data it represents,
because those tables can be re-used by subsequent blocks.
Finally, as far as I can tell, this restriction in the spec is not currently
enforced in any Zstandard implementation, nor has it ever been. This change
should therefore be safe to make.
* [ldm] Fix bug in overflow correction with large job size
* [zstdmt] Respect ZSTDMT_JOBSIZE_MAX (1G in 64-bit mode)
* [test] Add test that exposes the bug
Sadly the test fails on our CI because it uses too much memory, so
I had to comment it out.
