Fix only one half of a macro is executed in the correct side of the conditional,
causing the potential for hash corruption on calls to deflateParam() to change
level from 0 to something else.
Mika Lindqvist [Thu, 28 Apr 2016 19:48:15 +0000 (22:48 +0300)]
Add support for internal attribute
The advantage of this over hidden is for example that the compiler can
safely assume that pointers to functions declared internal can never be
passed externally. This allows the compiler to consider optimizations
otherwise impossible.
René J.V. Bertin [Thu, 11 Jun 2015 20:08:19 +0000 (22:08 +0200)]
CMakeLists.txt: use check_c_source_runs instead of check_c_source_compiles
to try to avoid using intrinsics and an instruction set the compiler
knows but the host CPU doesn't support.
René J.V. Bertin [Fri, 12 Jun 2015 13:13:49 +0000 (15:13 +0200)]
CMakeLists.txt : preliminary support for MSVC and ICC
- select the CMAKE_BUILD_TYPE "Release" by default if none has been set,
to ensure maximum generic optimisation possible on the host platform
- add WITH_NATIVE_INSTRUCTIONS to build with -march=native or its equivalent
option with other compilers (when we identify those alternatives)
- NATIVEFLAG (-march=native) will be used instead of -msseN/-mpclmul when
defined/requested
TODO: discuss whether -msseN/-mpclmul should be used only for the files that
need them instead of globally, while NATIVEFLAG can (is supposed to) be used
globally.
René J.V. Bertin [Thu, 11 Jun 2015 17:20:41 +0000 (19:20 +0200)]
CMakeLists.txt: better checking for Intel intrinsics.
The checks currently assume that instructions that build also execute.
This is not necessarily true: building with -msse4 on an AMD CPU (a C60)
that only has SSE4a leads to a crash in deflateInit2 when the compiler
apparently uses an unsupported instruction to set
s->hash_bits = memLevel + 7;
Phil Vachon [Mon, 30 Jan 2017 14:28:25 +0000 (15:28 +0100)]
Add block_open state for deflate_quick
By storing whether or not a block has been opened (or terminated), the
static trees used for the block and the end block markers can be emitted
appropriately.
Phil Vachon [Mon, 30 Jan 2017 14:20:20 +0000 (15:20 +0100)]
Fix Partial Symbol Generation for QUICK deflate
When using deflate_quick() in a streaming fashion and the output buffer
runs out of space while the input buffer still has data, deflate_quick()
would emit partial symbols. Force the deflate_quick() loop to terminate
for a flush before any further processing is done, returning to the main
deflate() routine to do its thing.
Mark Adler [Sun, 15 Jan 2017 16:22:16 +0000 (08:22 -0800)]
Permit immediate deflateParams changes before any deflate input.
This permits deflateParams to change the strategy and level right
after deflateInit, without having to wait until a header has been
written. The parameters can be changed immediately up until the
first deflate call that consumes any input data.
Mark Adler [Sun, 15 Jan 2017 16:15:55 +0000 (08:15 -0800)]
Update high water mark in deflate_stored.
This avoids unnecessary filling of bytes in the sliding window
buffer when switching from level zero to a non-zero level. This
also provides a consistent indication of deflate having taken
input for a later commit ...
Mark Adler [Sat, 3 Dec 2016 16:29:57 +0000 (08:29 -0800)]
Don't need to emit an empty fixed block when changing parameters.
gzsetparams() was using Z_PARTIAL_FLUSH when it could use Z_BLOCK
instead. This commit uses Z_BLOCK, which avoids emitting an
unnecessary ten bits into the stream.
Mark Adler [Sat, 3 Dec 2016 16:18:56 +0000 (08:18 -0800)]
Clean up gz* function return values.
In some cases the return values did not match the documentation,
or the documentation did not document all of the return values.
gzprintf() now consistently returns negative values on error,
which matches the behavior of the stdio fprintf() function.
Mark Adler [Sat, 5 Nov 2016 15:43:29 +0000 (08:43 -0700)]
Speed up deflation for level 0 (storing).
The previous code slid the window and the hash table and copied
every input byte three times in order to just write the data as
stored blocks with no compression. This commit minimizes sliding
and copying, especially for large input and output buffers.
Level 0 compression is now more than 20 times faster than before
the commit.
Most of the speedup is due to deferring hash table slides until
deflateParams() is called to change the compression level away
from 0. More speedup is due to copying directly from next_in to
next_out when the amounts of available input data and output space
permit it, avoiding the intermediate pending buffer. Additionally,
only the last 32K of the used input data is copied back to the
sliding window when large input buffers are provided.
Mark Adler [Wed, 23 Nov 2016 07:29:19 +0000 (23:29 -0800)]
Assure that deflateParams() will not switch functions mid-block.
This alters the specification in zlib.h, so that deflateParams()
will not change any parameters if there is not enough output space
in the event that a block is emitted in order to allow switching
the compression function.
Mark Adler [Sun, 30 Oct 2016 16:25:32 +0000 (09:25 -0700)]
Use memcpy for stored blocks.
This speeds up level 0 by about a factor of three, as compared to
the previous byte-at-a-time loop. We can do much better though. A
later commit avoids this copy for level 0 with large buffers,
instead copying directly from the input to the output. This commit
still speeds up storing incompressible data found when compressing
normally.
Original patch notes:
This updates the OS_CODE determination at compile time to match as
closely as possible the operating system mappings documented in
the PKWare APPNOTE.TXT version 6.3.4, section 4.4.2.2. That byte
in the gzip header is used by nobody for anything, as far as I can
tell. However we might as well try to set it appropriately.
Mark Adler [Tue, 25 Oct 2016 03:11:41 +0000 (20:11 -0700)]
Do a more thorough check of the state for every stream call.
This verifies that the state has been initialized, that it is the
expected type of state, deflate or inflate, and that at least the
first several bytes of the internal state have not been clobbered.
Mark Adler [Mon, 24 Oct 2016 22:52:19 +0000 (15:52 -0700)]
Reject a window size of 256 bytes if not using the zlib wrapper.
There is a bug in deflate for windowBits == 8 (256-byte window).
As a result, zlib silently changes a request for 8 to a request
for 9 (512-byte window), and sets the zlib header accordingly so
that the decompressor knows to use a 512-byte window. However if
deflateInit2() is used for raw deflate or gzip streams, then there
is no indication that the request was not honored, and the
application might assume that it can use a 256-byte window when
decompressing. This commit returns an error if the user requests
a 256-byte window when using raw deflate or gzip encoding.
Mark Adler [Tue, 4 Oct 2016 05:33:26 +0000 (22:33 -0700)]
Note the violation of the strict aliasing rule in crc32.c.
See the comment for more details. This is in response to an issue
raised as a result of a security audit of the zlib code by Trail
of Bits and TrustInSoft, in support of the Mozilla Foundation.
Mark Adler [Thu, 29 Sep 2016 03:20:25 +0000 (20:20 -0700)]
Avoid pre-decrement of pointer in big-endian CRC calculation.
There was a small optimization for PowerPCs to pre-increment a
pointer when accessing a word, instead of post-incrementing. This
required prefacing the loop with a decrement of the pointer,
possibly pointing before the object passed. This is not compliant
with the C standard, for which decrementing a pointer before its
allocated memory is undefined. When tested on a modern PowerPC
with a modern compiler, the optimization no longer has any effect.
Due to all that, and per the recommendation of a security audit of
the zlib code by Trail of Bits and TrustInSoft, in support of the
Mozilla Foundation, this "optimization" was removed, in order to
avoid the possibility of undefined behavior.
Mark Adler [Thu, 22 Sep 2016 06:35:50 +0000 (23:35 -0700)]
Remove offset pointer optimization in inftrees.c.
inftrees.c was subtracting an offset from a pointer to an array,
in order to provide a pointer that allowed indexing starting at
the offset. This is not compliant with the C standard, for which
the behavior of a pointer decremented before its allocated memory
is undefined. Per the recommendation of a security audit of the
zlib code by Trail of Bits and TrustInSoft, in support of the
Mozilla Foundation, this tiny optimization was removed, in order
to avoid the possibility of undefined behavior.
Mark Adler [Thu, 22 Sep 2016 05:25:21 +0000 (22:25 -0700)]
Use post-increment only in inffast.c.
An old inffast.c optimization turns out to not be optimal anymore
with modern compilers, and furthermore was not compliant with the
C standard, for which decrementing a pointer before its allocated
memory is undefined. Per the recommendation of a security audit of
the zlib code by Trail of Bits and TrustInSoft, in support of the
Mozilla Foundation, this "optimization" was removed, in order to
avoid the possibility of undefined behavior.
Mark Adler [Wed, 21 Sep 2016 01:49:21 +0000 (18:49 -0700)]
Add option to not compute or check check values.
The undocumented (except in these commit comments) function
inflateValidate(strm, check) can be called after an inflateInit(),
inflateInit2(), or inflateReset2() with check equal to zero to
turn off the check value (CRC-32 or Adler-32) computation and
comparison. Calling with check not equal to zero turns checking
back on. This should only be called immediately after the init or
reset function. inflateReset() does not change the state, so a
previous inflateValidate() setting will remain in effect.
This also turns off validation of the gzip header CRC when
present.
This should only be used when a zlib or gzip stream has already
been checked, and repeated decompressions of the same stream no
longer need to be validated.
Mika Lindqvist [Sun, 27 Mar 2016 12:02:54 +0000 (15:02 +0300)]
Merge insert_string and bulk_insert_str.
** Partial merge of this commit, based on a8c94e9f5a3b9d3c62182bcf84e72304a3c1a6e5
Excludes changes to fill_window_sse.c, changes to fill_window_c() in deflate.c
and several unrelated changes in the commit.