execSequence relied on pointer overflow to handle cases where
`sequence.matchLength < 8`. Instead of passing an `size_t` to
wildcopy, pass a `ptrdiff_t`.
Allows an adversary to write up to 3 bytes beyond the end of the buffer.
Occurs if the match overlaps the `extDict` and `currentPrefix`, and the
match length in the `currentPrefix` is less than `MINMATCH`, and
`op-(16-MINMATCH) >= oMatchEnd > op-16`.
* upstream/dev:
added doc\zstd_manual.html
added contrib\gen_html
zstd_compression_format.md moved to doc/
Fix small bug in ZSTD_execSequence()
improved ZSTD_compressBlock_opt_extDict_generic
protect ZSTD_decodeFrameHeader() from invalid usage, as suggested by @spaskob
zstd_opt.h: small improvement in compression ratio
improved dicitonary segment merge
use implicit rules to compile zstd_decompress.c
detect early impossible decompression scenario in legacy decoder v0.5
no repeat mode in legacy v0.5
fixed invalid invocation of dictionary in legacy decoder v0.5
fix edge case
fix command line interpretation
fixed minor corner case
zstd.h: added the Introduction section
fixed clang 3.5 warnings
zstd.h: updated comments
`memmove(op, match, sequence.matchLength)` is not the desired behavior.
Overlap is allowed, and handled as if we did `*op++ = *match++`, which
is not how `memmove()` handles overlap.
Only triggered if both of the following conditions are met:
* The match spans extDict & currentPrefixSegment
* `oLitEnd <= oend_w < oLitEnd + length1 < oMatchEnd <= oend`.
These two conditions imply that the block is less than 15 bytes long.
This bug isn't triggered by the streaming API, because it allocates
enough space for the window size + the block size, so there cannot be
a match that is within 8 bytes of the end and overlaps with itself.
It cannot be triggered by the block decompression API because all of
the decompressed data is in the currentPrefixSegment.
Introduced by commit 7158584399
If `weightTotal == 0`, then `BIT_highbit32(weightTotal)` is
undefined behavior in the case that it calls `__builtin_clz()`.
If `tableLog == HUF_TABLELOG_ABSOLUTEMAX` then we will access one
byte beyond the end of the buffer.
Caused by two things:
1. Not checking that `ip` is in range except for the first byte.
2. `ZSTDv0{5,6}_decodeLiteralsBlock()` could return a value larger than `srcSize`.
