When decompressing a seekable file, if seeking forward within
a frame (by issuing multiple ZSTD_seekable_decompress calls
with a small gap between them), the frame will be unnecessarily
reread from the beginning. This patch makes it continue using
the current frame data and simply skip over the unneeded bytes.
```
for f in $(find . \( -path ./.git -o -path ./tests/fuzz/corpora \) -prune -o -type f);
do
sed -i 's/Facebook, Inc\./Meta Platforms, Inc. and affiliates./' $f;
done
```
* seekable_format: fix from-file reading (not in-memory)
It tries to check the buffer boundary, but there is no buffer for
from-file reading.
* seekable_decompression: break when ZSTD_seekable_decompress() returns zero
* seekable_decompression_mem: break when ZSTD_seekable_decompress() returns zero
* seekable_format: cap the offset+len up to the last dOffset
This will allow to read the whole file w/o gotting corruption error if
the offset is more then the data left in file, i.e.:
$ ./seekable_compression seekable_compression.c 8192 | head
$ zstd -cdq seekable_compression.c.zst | wc -c
4737
Before this patch:
$ ./seekable_decompression seekable_compression.c.zst 0 10000000 | wc -c
ZSTD_seekable_decompress() error : Corrupted block detected
0
After:
$ ./seekable_decompression seekable_compression.c.zst 0 10000000 | wc -c
4737
These are replaced by the corresponding context resets. When
converting resetCStream, CCtx_setPledgedSrcSize isn't called if the
source size is "unknown".
This helps reduce the reliance on "static only" symbols, as well as
reducing the use of deprecated functions.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Memory constrained use cases that manage multiple archives benefit from
retaining multiple archive seek tables without retaining a ZSTD_seekable
instance for each.
* New opaque type for seek table: ZSTD_seekTable.
* ZSTD_seekable_copySeekTable() supports copying seek table out of a
ZSTD_seekable.
* ZSTD_seekTable_[eachSeekTableOp]() defines seek table API that mirrors
existing seek table operations.
* Existing ZSTD_seekable_[eachSeekTableOp]() retained; they delegate to
ZSTD_seekTable the variant.
These changes allow the above-mentioned use cases to initialize a
ZSTD_seekable, extract its ZSTD_seekTable, then throw the ZSTD_seekable
away to save memory. Standard ZSTD operations can then be used to
decompress frames based on seek table offsets.
The copy and delegate patterns are intended to minimize impact on
existing code and clients. Using copy instead of move for the infrequent
operation extracting a seek table ensures that the extraction does not
render the ZSTD_seekable useless. Delegating to *new* seek
table-oriented APIs ensures that this is not a breaking change for
existing clients while supporting all meaningful operations that depend
only on seek table data.
as suggested in #1441.
generally U32 and unsigned are the same thing,
except when they are not ...
case : 32-bit compilation for MIPS (uint32_t == unsigned long)
A vast majority of transformation consists in transforming U32 into unsigned.
In rare cases, it's the other way around (typically for internal code, such as seeds).
Among a few issues this patches solves :
- some parameters were declared with type `unsigned` in *.h,
but with type `U32` in their implementation *.c .
- some parameters have type unsigned*,
but the caller user a pointer to U32 instead.
These fixes are useful.
However, the bulk of changes is about %u formating,
which requires unsigned type,
but generally receives U32 values instead,
often just for brevity (U32 is shorter than unsigned).
These changes are generally minor, or even annoying.
As a consequence, the amount of code changed is larger than I would expect for such a patch.
Testing is also a pain :
it requires manually modifying `mem.h`,
in order to lie about `U32`
and force it to be an `unsigned long` typically.
On a 64-bit system, this will break the equivalence unsigned == U32.
Unfortunately, it will also break a few static_assert(), controlling structure sizes.
So it also requires modifying `debug.h` to make `static_assert()` a noop.
And then reverting these changes.
So it's inconvenient, and as a consequence,
this property is currently not checked during CI tests.
Therefore, these problems can emerge again in the future.
I wonder if it is worth ensuring proper distinction of U32 != unsigned in CI tests.
It's another restriction for coding, adding more frustration during merge tests,
since most platforms don't need this distinction (hence contributor will not see it),
and while this can matter in theory, the number of platforms impacted seems minimal.
Thoughts ?
