When --flush-timeout=TIMEOUT is used, xz will use
LZMA_SYNC_FLUSH if read() would block and at least
TIMEOUT milliseconds has elapsed since the previous flush.
This can be useful in realtime-like use cases where the
data is simultanously decompressed by another process
(possibly on a different computer). If new uncompressed
input data is produced slowly, without this option xz could
buffer the data for a long time until it would become
decompressible from the output.
If TIMEOUT is 0, the feature is disabled. This is the default.
This commit affects the compression side. Using xz for
the decompression side for the above purpose doesn't work
yet so well because there is quite a bit of input and
output buffering when decompressing.
The --long-help or man page were not updated yet.
The details of this feature may change.
Testing for end of file was no longer correct after full flushing
became possible with --block-size=SIZE and --block-list=SIZES.
There was no bug in practice though because xz just made a few
unneeded zero-byte reads.
This switches units from microseconds to milliseconds.
New clock_gettime(CLOCK_MONOTONIC) will be used if available.
There is still a fallback to gettimeofday().
The man pages of lzmainfo, xzmore, and xzdec had similar
constructs as the man page of xz had before the commit
eb6ca9854b. Eric S. Raymond
didn't mention these man pages in his bug report, but
it's nice to be consistent.
Now both reading and writing should be without
race conditions with signals.
They might still be signal handling issues left.
Signals are blocked during many operations to avoid
EINTR but it may cause problems e.g. if writing to
stderr blocks when trying to display an error message.
It is possible that a signal to set user_abort arrives right
before a blocking system call is made. In this case the call
may block until another signal arrives, while the wanted
behavior is to make xz clean up and exit as soon as possible.
After this commit, the race condition is avoided with the
input side which already uses non-blocking I/O. The output
side still uses blocking I/O and thus has the race condition.
POSIX says that fcntl(fd, F_SETFL, flags) returns -1 on
error and "other than -1" on success. This is how it is
documented e.g. on OpenBSD too. On Linux, success with
F_SETFL is always 0 (at least accorinding to fcntl(2)
from man-pages 3.51).
Due to a wrong variable name, when writing a sparse file
to standard output, *all* file status flags were cleared
(to the extent the operating system allowed it) instead of
only clearing the O_APPEND flag. In practice this worked
fine in the common situations on GNU/Linux, but I didn't
check how it behaved elsewhere.
The original flags were still restored correctly. I still
changed the code to use a separate boolean variable to
indicate when the flags should be restored instead of
relying on a special value in stdout_flags.
Input file can be a FIFO or something else that doesn't
support posix_fadvise() so don't check the return value
even with an assertion. Nothing bad happens if the call
to posix_fadvise() fails.
It is a no-op for now, but if an old xz version is used
together with a newer liblzma that supports something new,
then this check becomes important and will stop the old xz
from trying to parse files that it won't understand.
It should actually still work with Automake 1.10 if
the serial-tests option is removed. Automake 1.13 started
using parallel tests by default and the option to get
the old behavior isn't supported before 1.12.
At least for now, parallel tests don't improve anything
in XZ Utils but they hide the progress output from
test_compress.sh.
This affects only "xz -lvv". Normal decompression with xz
already detected if Block Header and Index had mismatched
Uncompressed Size fields. So this just makes "xz -lvv"
show such files as corrupt instead of showing the
Uncompressed Size from Index.
Now the interaction of presets and custom filter chains
is described correctly. Earlier it contradicted itself.
Thanks to DevHC who reported these issues on IRC to me
on 2012-12-14.
There was somewhat illogical behavior when --extreme was
specified and mixed with custom filter chains.
Before this commit, "xz -9 --lzma2 -e" was equivalent
to "xz --lzma2". After it is equivalent to "xz -6e"
(all earlier preset options get forgotten when a custom
filter chain is specified and the default preset is 6
to which -e is applied). I find this less illogical.
This also affects the meaning of "xz -9e --lzma2 -7".
Earlier it was equivalent to "xz -7e" (the -e specified
before a custom filter chain wasn't forgotten). Now it
is "xz -7". Note that "xz -7e" still is the same as "xz -e7".
Hopefully very few cared about this in the first place,
so pretty much no one should even notice this change.
Thanks to Conley Moorhous.
Variable-length arrays are mandatory in C99 but optional in C11.
The code doesn't currently use any VLAs and it shouldn't in the
future either to stay compatible with C11 without requiring any
optional C11 features.
The options are now ordered in the same order as in xz's help
message.
Descriptions were added to the options that are ignored.
I left them in parenthesis even if it looks a bit weird
because I find it easier to spot the ignored vs. non-ignored
options from the list that way.
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).
Use "read" instead of "awk" in xzless to get the version
number of "less". The need for awk was introduced in
the commit db5c1817fa.
Thanks to Ariel P for the patch.
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.
In v4.999.9beta~30 (xzless: Support compressed standard input,
2009-08-09), xzless learned to parse ‘less -V’ output to figure out
whether less is new enough to handle $LESSOPEN settings starting
with “|-”. That worked well for a while, but the version string from
‘less’ versions 448 (June, 2012) is misparsed, producing a warning:
$ xzless /tmp/test.xz; echo $?
/usr/bin/xzless: line 49: test: 456 (GNU regular expressions): \
integer expression expected
0
More precisely, modern ‘less’ lists the regexp implementation along
with its version number, and xzless passes the entire version number
with attached parenthetical phrase as a number to "test $a -gt $b",
producing the above confusing message.
$ less-444 -V | head -1
less 444
$ less -V | head -1
less 456 (no regular expressions)
So relax the pattern matched --- instead of expecting "less <number>",
look for a line of the form "less <number>[ (extra parenthetical)]".
While at it, improve the behavior when no matching line is found ---
instead of producing a cryptic message, we can fall back on a LESSPIPE
setting that is supported by all versions of ‘less’.
The implementation uses "awk" for simplicity. Hopefully that’s
portable enough.
Reported-by: Jörg-Volker Peetz <jvpeetz@web.de>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Lasse Collin
Anders F Bjorklund
Jeff Bastian
Jonathan Nieder