For several people, the limiter causes bigger problems that
it solves, so it is better to have it disabled by default.
Those who want to have a limiter by default need to enable
it via the environment variable XZ_DEFAULTS.
Support for environment variable XZ_DEFAULTS was added. It is
parsed before XZ_OPT and technically identical with it. The
intended uses differ quite a bit though; see the man page.
The memory usage limit can now be set separately for
compression and decompression using --memlimit-compress and
--memlimit-decompress. To set both at once, -M or --memlimit
can be used. --memory was retained as a legacy alias for
--memlimit for backwards compatibility.
The semantics of --info-memory were changed in backwards
incompatible way. Compatibility wasn't meaningful due to
changes in the memory usage limiter functionality.
The memory usage limiter info is no longer shown at the
bottom of xz --long -help.
The memory usage limiter support for removed completely from xzdec.
xz's man page was updated to match the above changes. Various
unrelated fixes were also made to the man page.
message_filters_to_str() converts the filter chain to
a string. message_filters_show() replaces the original
message_filters().
uint32_to_optstr() was also added to show the dictionary
size in nicer format when possible.
The extra space for showing both has been taken from the
sizes field. If the sizes grow big, bigger units than MiB
will be used. It makes it slightly difficult to see that
progress is still happening with huge files, but it should
be OK in practice.
Thanks to Trent W. Buck for <http://bugs.debian.org/574583>
and Jonathan Nieder for suggestions how to fix it.
Originally both base-2 and base-10 were supported, but since
there seems to be little need for base-10 in XZ Utils, treat
everything as base-2 and also be more relaxed about the case
of the first letter of the suffix. Now xz will accept e.g.
KiB, Ki, k, K, kB, and KB, and interpret them all as 1024. The
recommended spelling of the suffixes are still KiB, MiB, and GiB.
It still feels a bit wrong to round 1 byte to 1 MiB but
at least it is now done consistently so that the same
byte value is always rounded the same way to MiB.
Previously the default limit was always 40 % of RAM. The
new limit is a little bit more complex:
- If 40 % of RAM is at least 80 MiB, 40 % of RAM is used
as the limit.
- If 80 % of RAM is over 80 MiB, 80 MiB is used as the limit.
- Otherwise 80 % of RAM is used as the limit.
This should make it possible to decompress files created with
"xz -9" on more systems. Swapping is generally more expected
on systems with less RAM, so higher default limit on them
shouldn't cause too bad surprises in terms of heavy swapping.
Instead, the higher default limit should reduce the number of
bad surprises when it used to prevent decompression of files
created with "xz -9". The DoS prevention system shouldn't be
a DoS itself.
Note that even with the new default limit, a system with 64 MiB
RAM cannot decompress files created with "xz -9" without user
overriding the limit. This should be OK, because if xz is going
to need more memory than the system has RAM, it will run very
very slowly and thus it's good that user has to override the limit
in that case.
If signal handlers haven't been established, then it's
useless to try to block them, especially since the sigset_t
used for blocking hasn't been initialized yet.
The opening of the destination file is now delayed a little.
The coder is initialized, and if decompressing, the memory
usage of the first Block compared against the memory
usage limit before the destination file is opened. This
means that if --force was used, the old "target" file won't
be deleted so easily when something goes wrong very early.
Thanks to Mark K for the bug report.
The above fix required some changes to progress message
handling. Now there is a separate function for setting and
printing the filename. It is used also in list.c.
list_file() now handles stdin correctly (gives an error).
A useless check for user_abort was removed from file_io.c.
This is a bit rough but should be useful for basic things.
Ideas (with detailed examples) about the output format are
welcome.
The output of --robot --list is not necessarily stable yet,
although I don't currently have any plans about changing it.
The man page hasn't been updated yet.
