Now --block-list=SIZES works with in the threaded mode too,
although the performance is still bad due to the use of
LZMA_FULL_FLUSH instead of the new LZMA_FULL_BARRIER.
Now liblzma only uses "mythread" functions and types
which are defined in mythread.h matching the desired
threading method.
Before Windows Vista, there is no direct equivalent to
pthread condition variables. Since this package doesn't
use pthread_cond_broadcast(), pre-Vista threading can
still be kept quite simple. The pre-Vista code doesn't
use anything that wasn't already available in Windows 95,
so the binaries should run even on Windows 95 if someone
happens to care.
To avoid false positives when detecting .lzma files,
rare values in dictionary size and uncompressed size fields
were rejected. They will still be rejected if .lzma files
are decoded with lzma_auto_decoder(), but when using
lzma_alone_decoder() directly, such files will now be accepted.
Hopefully this is an OK compromise.
This doesn't affect xz because xz still has its own file
format detection code. This does affect lzmadec though.
So after this commit lzmadec will accept files that xz or
xz-emulating-lzma doesn't.
NOTE: lzma_alone_decoder() still won't decode all .lzma files
because liblzma's LZMA decoder doesn't support lc + lp > 4.
Reported here:
http://sourceforge.net/projects/lzmautils/forums/forum/708858/topic/7068827
This race condition could cause a deadlock if lzma_end() was
called before finishing the encoding. This can happen with
xz with debugging enabled (non-debugging version doesn't
call lzma_end() before exiting).
This adds lzma_get_progress() to liblzma and takes advantage
of it in xz.
lzma_get_progress() collects progress information from
the thread-specific structures so that fairly accurate
progress information is available to applications. Adding
a new function seemed to be a better way than making the
information directly available in lzma_stream (like total_in
and total_out are) because collecting the information requires
locking mutexes. It's waste of time to do it more often than
the up to date information is actually needed by an application.
There is a tiny risk of causing breakage: If an application
assigns lzma_stream.allocator to a non-const pointer, such
code won't compile anymore. I don't know why anyone would do
such a thing though, so in practice this shouldn't cause trouble.
Thanks to Jan Kratochvil for the patch.
Spot candidates by running these commands:
git ls-files |xargs perl -0777 -n \
-e 'while (/\b(then?|[iao]n|i[fst]|but|f?or|at|and|[dt]o)\s+\1\b/gims)' \
-e '{$n=($` =~ tr/\n/\n/ + 1); ($v=$&)=~s/\n/\\n/g; print "$ARGV:$n:$v\n"}'
Thanks to Jim Meyering for the original patch.
This is the simplest method to do threading, which splits
the uncompressed data into blocks and compresses them
independently from each other. There's room for improvement
especially to reduce the memory usage, but nevertheless,
this is a good start.
Empty Block was created if the input buffer was empty.
Empty Block wastes a few bytes of space, but more importantly
it triggers a bug in XZ Utils 5.0.1 and older when trying
to decompress such a file. 5.0.1 and older consider such
files to be corrupt. I thought that no encoder creates empty
Blocks when releasing 5.0.2 but I was wrong.
The biggest problem was that the integrity check type
wasn't validated, and e.g. lzma_easy_buffer_encode()
would create a corrupt .xz Stream if given an unsupported
Check ID. Luckily applications don't usually try to use
an unsupport Check ID, so this bug is unlikely to cause
many real-world problems.
It leaks old filter options structures (hundred bytes or so)
every time the lzma_stream is reinitialized. With the xz tool,
this happens when compressing multiple files.
If any of the reserved members in lzma_stream are non-zero
or non-NULL, LZMA_OPTIONS_ERROR is returned. It is possible
that a new feature in the future is indicated by just setting
a reserved member to some other value, so the old liblzma
version need to catch it as an unsupported feature.
With bad luck, lzma_code() could return LZMA_BUF_ERROR
when it shouldn't.
This has been here since the early days of liblzma.
It got triggered by the modifications made to the xz
tool in commit 18c10c30d2
but only when decompressing .lzma files. Somehow I managed
to miss testing that with Valgrind earlier.
This fixes <http://bugs.gentoo.org/show_bug.cgi?id=305591>.
Thanks to Rafał Mużyło for helping to debug it on IRC.
lzma_block.version has to be initialized even for
lzma_block_header_decode(). This way a future version
of liblzma won't allocate memory in a way that an old
application doesn't know how to free it.
The subtlety of this change is that all current apps
using lzma_block_header_decode() will keep working for
now, because the only possible version value is zero,
and lzma_block_header_decode() unconditionally sets the
version to zero even now. Unless fixed, these apps will
break in the future if a new version of the Block options
is ever needed.
This breaks API and ABI but most apps are not affected
since most apps don't use this part of the API. You will
get a compile error if you are using anything that got
broken.
Summary of changes:
- Ability to store Stream Flags, which are needed
for random-access reading in multi-Stream files.
- Separate function to set size of Stream Padding.
- Iterator structure makes it possible to read the same
lzma_index from multiple threads at the same time.
- A lot faster code to locate Blocks.
- Removed lzma_index_equal() without adding anything
to replace it. I don't know what it should do exactly
with the new features and what actually needs this
function in the first place other than test_index.c,
which now has its own code to compare lzma_indexes.
lzma_index_read() didn't skip over Stream Padding
if it was the first record in the Index.
lzma_index_cat() didn't combine small Indexes correctly.
The test suite was updated to check for these bugs.
These bugs didn't affect the xz command line tool or
most users of liblzma in any way.
The Index decoder code didn't perfectly match the API docs,
which said that *i will be set to point to the decoded Index
only after decoding has succeeded. The docs were a bit unclear
too.
Now the decoder will initially set *i to NULL. *i will be set
to point to the decoded Index once decoding has succeeded.
This simplifies applications too, since it avoids dangling
pointers.
I had hoped to keep liblzma as purely a compression
library as possible (e.g. file I/O will go into
a different library), but it seems that applications
linking agaisnt liblzma need some way to determine
the memory usage limit, and knowing the amount of RAM
is one reasonable way to help making such decisions.
Thanks to Jonathan Nieder for the original patch.
Originally the idea was that using LZMA_FULL_FLUSH
with Stream encoder would read the filter chain
from the same array that was used to intialize the
Stream encoder. Since most apps wouldn't use
LZMA_FULL_FLUSH, most apps wouldn't need to keep
the filter chain available after initializing the
Stream encoder. However, due to my mistake, it
actually required keeping the array always available.
Since setting the new filter chain via the array
used at initialization time is not a nice way to do
it for a couple of reasons, this commit ditches it
and introduces lzma_filters_update(). This new function
replaces also the "persistent" flag used by LZMA2
(and to-be-designed Subblock filter), which was also
an ugly thing to do.
Thanks to Alexey Tourbin for reminding me about the problem
that Stream encoder used to require keeping the filter
chain allocated.
Lasse Collin