The documentation states LZMA_PROG_ERROR can be returned from
lzma_index_cat. Previously, lzma_index_cat could not return
LZMA_PROG_ERROR. Now, the validation is similar to
lzma_index_append, which does a NULL check on the index
parameter.
The check type of the last Stream in dest was never copied to
dest->checks (the code tried to copy it but it was done too late).
This meant that the value returned by lzma_index_checks() would
only include the check type of the last Stream when multiple
lzma_indexes had been concatenated.
In xz --list this meant that the summary would only list the
check type of the last Stream, so in this sense this was only
a visual bug. However, it's possible that some applications
use this information for purposes other than merely showing
it to the users in an informational message. I'm not aware of
such applications though and it's quite possible that such
applications don't exist.
Regular streamed decompression in xz or any other application
doesn't use lzma_index_cat() and so this bug cannot affect them.
If lzma_code() returns LZMA_MEMLIMIT_ERROR it is now possible
to use lzma_memlimit_set() to increase the limit and continue
decoding. This was supposed to work from the beginning but
there was a bug. With other decoders (.lzma or threaded .xz)
this already worked correctly.
Running the current xzgrep on Slackware 10.1 with GNU bash 3.00.15:
xzgrep: line 231: syntax error near unexpected token `;;'
On SCO OpenServer 5.0.7 with Korn Shell 93r:
syntax error at line 231 : `;;' unexpected
Turns out that some old shells don't like apostrophes (') inside
command substitutions. For example, the following fails:
x=$(echo foo
# asdf'zxcv
echo bar)
printf '%s\n' "$x"
The problem was introduced by commits
69d1b3fc29 (2022-03-29),
bd7b290f3f (2022-07-18), and
a648978b20 (2022-07-19).
5.2.6 is the only stable release that included
this problem.
Thanks to Kevin R. Bulgrien for reporting the problem
on SCO OpenServer 5.0.7 and for providing the fix.
lzma_stream_encoder() and lzma_stream_encoder_mt() always assumed
this. Before this patch, failing lzma_filters_copy() could result
in free(invalid_pointer) or invalid memory reads in stream_encoder.c
or stream_encoder_mt.c.
To trigger this, allocating memory for a filter options structure
has to fail. These are tiny allocations so in practice they very
rarely fail.
Certain badness in the filter chain array could also make
lzma_filters_copy() fail but both stream_encoder.c and
stream_encoder_mt.c validate the filter chain before
trying to copy it, so the crash cannot occur this way.
The documentation in src/liblzma/api/lzma/index.h suggests that
both the unpadded (compressed) size and the uncompressed size
are checked for overflow, but only the unpadded size was checked.
The uncompressed check is done first since that is more likely to
occur than the unpadded or index field size overflows.
RHEL/CentOS 7 shipped with 5.1.2alpha, including the threaded
encoder that is behind #ifdef LZMA_UNSTABLE in the API headers.
In 5.1.2alpha these symbols are under XZ_5.1.2alpha in liblzma.map.
API/ABI compatibility tracking isn't done between development
releases so newer releases didn't have XZ_5.1.2alpha anymore.
Later RHEL/CentOS 7 updated xz to 5.2.2 but they wanted to keep
the exported symbols compatible with 5.1.2alpha. After checking
the ABI changes it turned out that >= 5.2.0 ABI is backward
compatible with the threaded encoder functions from 5.1.2alpha
(but not vice versa as fixes and extensions to these functions
were made between 5.1.2alpha and 5.2.0).
In RHEL/CentOS 7, XZ Utils 5.2.2 was patched with
xz-5.2.2-compat-libs.patch to modify liblzma.map:
- XZ_5.1.2alpha was added with lzma_stream_encoder_mt and
lzma_stream_encoder_mt_memusage. This matched XZ Utils 5.1.2alpha.
- XZ_5.2 was replaced with XZ_5.2.2. It is clear that this was
an error; the intention was to keep using XZ_5.2 (XZ_5.2.2
has never been used in XZ Utils). So XZ_5.2.2 lists all
symbols that were listed under XZ_5.2 before the patch.
lzma_stream_encoder_mt and _mt_memusage are included too so
they are listed both here and under XZ_5.1.2alpha.
The patch didn't add any __asm__(".symver ...") lines to the .c
files. Thus the resulting liblzma.so exports the threaded encoder
functions under XZ_5.1.2alpha only. Listing the two functions
also under XZ_5.2.2 in liblzma.map has no effect without
matching .symver lines.
The lack of XZ_5.2 in RHEL/CentOS 7 means that binaries linked
against unpatched XZ Utils 5.2.x won't run on RHEL/CentOS 7.
This is unfortunate but this alone isn't too bad as the problem
is contained within RHEL/CentOS 7 and doesn't affect users
of other distributions. It could also be fixed internally in
RHEL/CentOS 7.
The second problem is more serious: In XZ Utils 5.2.2 the API
headers don't have #ifdef LZMA_UNSTABLE for obvious reasons.
This is true in RHEL/CentOS 7 version too. Thus now programs
using new APIs can be compiled without an extra #define. However,
the programs end up depending on symbol version XZ_5.1.2alpha
(and possibly also XZ_5.2.2) instead of XZ_5.2 as they would
with an unpatched XZ Utils 5.2.2. This means that such binaries
won't run on other distributions shipping XZ Utils >= 5.2.0 as
they don't provide XZ_5.1.2alpha or XZ_5.2.2; they only provide
XZ_5.2 (and XZ_5.0). (This includes RHEL/CentOS 8 as the patch
luckily isn't included there anymore with XZ Utils 5.2.4.)
Binaries built by RHEL/CentOS 7 users get distributed and then
people wonder why they don't run on some other distribution.
Seems that people have found out about the patch and been copying
it to some build scripts, seemingly curing the symptoms but
actually spreading the illness further and outside RHEL/CentOS 7.
The ill patch seems to be from late 2016 (RHEL 7.3) and in 2017 it
had spread at least to EasyBuild. I heard about the events only
recently. :-(
This commit splits liblzma.map into two versions: one for
GNU/Linux and another for other OSes that can use symbol versioning
(FreeBSD, Solaris, maybe others). The Linux-specific file and the
matching additions to .c files add full compatibility with binaries
that have been built against a RHEL/CentOS-patched liblzma. Builds
for OSes other than GNU/Linux won't get the vaccine as they should
be immune to the problem (I really hope that no build script uses
the RHEL/CentOS 7 patch outside GNU/Linux).
The RHEL/CentOS compatibility symbols XZ_5.1.2alpha and XZ_5.2.2
are intentionally put *after* XZ_5.2 in liblzma_linux.map. This way
if one forgets to #define HAVE_SYMBOL_VERSIONS_LINUX when building,
the resulting liblzma.so.5 will have lzma_stream_encoder_mt@@XZ_5.2
since XZ_5.2 {...} is the first one that lists that function.
Without HAVE_SYMBOL_VERSIONS_LINUX @XZ_5.1.2alpha and @XZ_5.2.2
will be missing but that's still a minor problem compared to
only having lzma_stream_encoder_mt@@XZ_5.1.2alpha!
The "local: *;" line was moved to XZ_5.0 so that it doesn't need
to be moved around. It doesn't matter where it is put.
Having two similar liblzma_*.map files is a bit silly as it is,
at least for now, easily possible to generate the generic one
from the Linux-specific file. But that adds extra steps and
increases the risk of mistakes when supporting more than one
build system. So I rather maintain two files in parallel and let
validate_map.sh check that they are in sync when "make mydist"
is run.
This adds .symver lines for lzma_stream_encoder_mt@XZ_5.2.2 and
lzma_stream_encoder_mt_memusage@XZ_5.2.2 even though these
weren't exported by RHEL/CentOS 7 (only @@XZ_5.1.2alpha was
for these two). I added these anyway because someone might
misunderstand the RHEL/CentOS 7 patch and think that @XZ_5.2.2
(@@XZ_5.2.2) versions were exported too.
At glance one could suggest using __typeof__ to copy the function
prototypes when making aliases. However, this doesn't work trivially
because __typeof__ won't copy attributes (lzma_nothrow, lzma_pure)
and it won't change symbol visibility from hidden to default (done
by LZMA_API()). Attributes could be copied with __copy__ attribute
but that needs GCC 9 and a fallback method would be needed anyway.
This uses __symver__ attribute with GCC >= 10 and
__asm__(".symver ...") with everything else. The attribute method
is required for LTO (-flto) support with GCC. Using -flto with
GCC older than 10 is now broken on GNU/Linux and will not be fixed
(can silently result in a broken liblzma build that has dangerously
incorrect symbol versions). LTO builds with Clang seem to work
with the traditional __asm__(".symver ...") method.
Thanks to Boud Roukema for reporting the problem and discussing
the details and testing the fix.
Previously this required using --force but that has other
effects too which might be undesirable. Changing the behavior
of --keep has a small risk of breaking existing scripts but
since this is a fairly special corner case I expect the
likehood of breakage to be low enough.
I think the new behavior is more logical. The only reason for
the old behavior was to be consistent with gzip and bzip2.
Thanks to Vincent Lefevre and Sebastian Andrzej Siewior.
xzgrep wouldn't exit on SIGPIPE or SIGQUIT when it clearly
should have. It's quite possible that it's not perfect still
but at least it's much better.
If multiple exit statuses compete, now it tries to pick
the largest of value.
Some comments were added.
The exit status handling of signals is still broken if the shell
uses values larger than 255 in $? to indicate that a process
died due to a signal ***and*** their "exit" command doesn't take
this into account. This seems to work well with the ksh and yash
versions I tried. However, there is a report in gzip/zgrep that
OpenSolaris 5.11 (not 5.10) has a problem with "exit" truncating
the argument to 8 bits:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22900#25
Such a bug would break xzgrep but I didn't add a workaround
at least for now. 5.11 is old and I don't know if the problem
exists in modern descendants, or if the problem exists in other
ksh implementations in use.
I don't know if this can make a difference in the real world
but it looked kind of suspicious (what happens with sed
implementations that cannot process very long lines?).
At least this commit shouldn't make it worse.
It avoids the use of sed for prefixing filenames to output lines.
Using sed for that is slower and prone to security bugs so now
the sed method is only used as a fallback.
This also fixes an actual bug: When grepping a binary file,
GNU grep nowadays prints its diagnostics to stderr instead of
stdout and thus the sed-method for prefixing the filename doesn't
work. So with this commit grepping binary files gives reasonable
output with GNU grep now.
This was inspired by zgrep but the implementation is different.
Also replace one use of expr with printf.
The rationale for LC_ALL=C was already mentioned in
69d1b3fc29 that fixed a security
issue. However, unrelated uses weren't changed in that commit yet.
POSIX says that with sed and such tools one should use LC_ALL=C
to ensure predictable behavior when strings contain byte sequences
that aren't valid multibyte characters in the current locale. See
under "Application usage" in here:
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html
With GNU sed invalid multibyte strings would work without this;
it's documented in its Texinfo manual. Some other implementations
aren't so forgiving.
Fix handling of "xzgrep -25 foo" (in GNU grep "grep -25 foo" is
an alias for "grep -C25 foo"). xzgrep would treat "foo" as filename
instead of as a pattern. This bug was fixed in zgrep in gzip in 2012.
Add -E, -F, -G, and -P to the "no argument required" list.
Add -X to "argument required" list. It is an
intentionally-undocumented GNU grep option so this isn't
an important option for xzgrep but it seems that other grep
implementations (well, those that I checked) don't support -X
so I hope this change is an improvement still.
grep -d (grep --directories=ACTION) requires an argument. In
contrast to zgrep, I kept -d in the "no argument required" list
because it's not supported in xzgrep (or zgrep). This way
"xzgrep -d" gives an error about option being unsupported instead
of telling that it requires an argument. Both zgrep and xzgrep
tell that it's unsupported if an argument is specified.
Add comments.
Turns out that this is needed for .lzma files as the spec in
LZMA SDK says that end marker may be present even if the size
is stored in the header. Such files are rare but exist in the
real world. The code in liblzma is so old that the spec didn't
exist in LZMA SDK back then and I had understood that such
files weren't possible (the lzma tool in LZMA SDK didn't
create such files).
This modifies the internal API so that LZMA decoder can be told
if EOPM is allowed even when the uncompressed size is known.
It's allowed with .lzma and not with other uses.
Thanks to Karl Beldan for reporting the problem.
Malicious filenames can make xzgrep to write to arbitrary files
or (with a GNU sed extension) lead to arbitrary code execution.
xzgrep from XZ Utils versions up to and including 5.2.5 are
affected. 5.3.1alpha and 5.3.2alpha are affected as well.
This patch works for all of them.
This bug was inherited from gzip's zgrep. gzip 1.12 includes
a fix for zgrep.
The issue with the old sed script is that with multiple newlines,
the N-command will read the second line of input, then the
s-commands will be skipped because it's not the end of the
file yet, then a new sed cycle starts and the pattern space
is printed and emptied. So only the last line or two get escaped.
One way to fix this would be to read all lines into the pattern
space first. However, the included fix is even simpler: All lines
except the last line get a backslash appended at the end. To ensure
that shell command substitution doesn't eat a possible trailing
newline, a colon is appended to the filename before escaping.
The colon is later used to separate the filename from the grep
output so it is fine to add it here instead of a few lines later.
The old code also wasn't POSIX compliant as it used \n in the
replacement section of the s-command. Using \<newline> is the
POSIX compatible method.
LC_ALL=C was added to the two critical sed commands. POSIX sed
manual recommends it when using sed to manipulate pathnames
because in other locales invalid multibyte sequences might
cause issues with some sed implementations. In case of GNU sed,
these particular sed scripts wouldn't have such problems but some
other scripts could have, see:
info '(sed)Locale Considerations'
This vulnerability was discovered by:
cleemy desu wayo working with Trend Micro Zero Day Initiative
Thanks to Jim Meyering and Paul Eggert discussing the different
ways to fix this and for coordinating the patch release schedule
with gzip.
If lzma_index_append() failed (most likely memory allocation failure)
it could have gone unnoticed and the resulting .xz file would have
an incorrect Index. Decompressing such a file would produce the
correct uncompressed data but then an error would occur when
verifying the Index field.
Now it limits the input and output buffer sizes that are
passed to a raw decoder. This way there's no need to check
if the sizes can grow too big or overflow when updating
Compressed Size and Uncompressed Size counts. This also means
that a corrupt file cannot cause the raw decoder to process
useless extra input or output that would exceed the size info
in Block Header (and thus cause LZMA_DATA_ERROR anyway).
More importantly, now the size information is verified more
carefully in case raw decoder returns LZMA_OK. This doesn't
really matter with the current single-threaded .xz decoder
as the errors would be detected slightly later anyway. But
this helps avoiding corner cases in the upcoming threaded
decompressor, and it might help other Block decoder uses
outside liblzma too.
The test files bad-1-lzma2-{9,10,11}.xz test these conditions.
With the single-threaded .xz decoder the only difference is
that LZMA_DATA_ERROR is detected in a difference place now.
Previously lzma_lzma_props_encode() and lzma_lzma2_props_encode()
assumed that the options pointers must be non-NULL because the
with these filters the API says it must never be NULL. It is
good to do these checks anyway.
OpenBSD does not allow to change the group of a file if the user
does not belong to this group. In contrast to Linux, OpenBSD also
fails if the new group is the same as the old one. Do not call
fchown(2) in this case, it would change nothing anyway.
This fixes an issue with Perl Alien::Build module.
https://github.com/PerlAlien/Alien-Build/issues/62
Sometimes the version number from "less -V" contains a dot,
sometimes not. xzless failed detect the version number when
it does contain a dot. This fixes it.
Thanks to nick87720z for reporting this. Apparently it had been
reported here <https://bugs.gentoo.org/489362> in 2013.
Due to architectural limitations, address space available to a single
userspace process on MIPS32 is limited to 2 GiB, not 4, even on systems
that have more physical RAM -- e.g. 64-bit systems with 32-bit
userspace, or systems that use XPA (an extension similar to x86's PAE).
So, for MIPS32, we have to impose stronger memory limits. I've chosen
2000MiB to give the process some headroom.
Omit the -q option from xz, gzip, and bzip2. With xz this shouldn't
matter. With gzip it's important because -q makes gzip replace SIGPIPE
with exit status 2. With bzip2 it's important because with -q bzip2
is completely silent if input is corrupt while other decompressors
still give an error message.
Avoiding exit status 2 from gzip is important because bzip2 uses
exit status 2 to indicate corrupt input. Before this commit xzgrep
didn't recognize corrupt .bz2 files because xzgrep was treating
exit status 2 as SIGPIPE for gzip compatibility.
zstd still needs -q because otherwise it is noisy in normal
operation.
The code to detect real SIGPIPE didn't check if the exit status
was due to a signal (>= 128) and so could ignore some other exit
status too.
This is a minor fix since this affects only the situation when
the files differ and the exit status is something else than 0.
In such case there could be SIGPIPE from a decompression tool
and that would result in exit status of 2 from xzdiff/xzcmp
while the correct behavior would be to return 1 or whatever
else diff or cmp may have returned.
This commit omits the -q option from xz/gzip/bzip2/lzop arguments.
I'm not sure why the -q was used in the first place, perhaps it
hides warnings in some situation that I cannot see at the moment.
Hopefully the removal won't introduce a new bug.
With gzip the -q option was harmful because it made gzip return 2
instead of >= 128 with SIGPIPE. Ignoring exit status 2 (warning
from gzip) isn't practical because bzip2 uses exit status 2 to
indicate corrupt input file. It's better if SIGPIPE results in
exit status >= 128.
With bzip2 the removal of -q seems to be good because with -q
it prints nothing if input is corrupt. The other tools aren't
silent in this situation even with -q. On the other hand, if
zstd support is added, it will need -q since otherwise it's
noisy in normal situations.
Thanks to Étienne Mollier and Sebastian Andrzej Siewior.
When Intel CET is enabled, we need to include <cet.h> in assembly codes
to mark Intel CET support and add _CET_ENDBR to indirect jump targets.
Tested on Intel Tiger Lake under CET enabled Linux.
I don't want to use \c in macro arguments but groff_man(7)
suggests that \f has better portability. \f would be needed
for the .TP strings for portability reasons anyway.
Thanks to Bjarni Ingi Gislason.
A few are simply omitted, most are converted to "for example"
and surrounded with commas. Sounds like that this is better
style, for example, man-pages(7) recommends avoiding such
abbreviations except in parenthesis.
Thanks to Bjarni Ingi Gislason.
Docs of ancient troff/nroff mention \(em (em-dash) but not \(en
and \- was used for both minus and en-dash. I don't know how
portable \(en is nowadays but it can be changed back if someone
complains. At least GNU groff and OpenBSD's mandoc support it.
Thanks to Bjarni Ingi Gislason for the patch.
Output is from: test-groff -b -e -mandoc -T utf8 -rF0 -t -w w -z
[ "test-groff" is a developmental version of "groff" ]
Input file is ./src/scripts/xzgrep.1
<src/scripts/xzgrep.1>:20 (macro RB): only 1 argument, but more are expected
<src/scripts/xzgrep.1>:23 (macro RB): only 1 argument, but more are expected
<src/scripts/xzgrep.1>:26 (macro RB): only 1 argument, but more are expected
<src/scripts/xzgrep.1>:29 (macro RB): only 1 argument, but more are expected
<src/scripts/xzgrep.1>:32 (macro RB): only 1 argument, but more are expected
"abc..." does not mean the same as "abc ...".
The output from nroff and troff is unchanged except for the space
between "file" and "...".
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
Summary:
mandoc -T lint xzgrep.1 :
mandoc: xzgrep.1:79:2: WARNING: skipping paragraph macro: PP empty
There is no change in the output of "nroff" and "troff".
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
Output is from: test-groff -b -e -mandoc -T utf8 -rF0 -t -w w -z
[ "test-groff" is a developmental version of "groff" ]
Input file is ./src/xz/xz.1
<src/xz/xz.1>:408 (macro BR): only 1 argument, but more are expected
<src/xz/xz.1>:1009 (macro BR): only 1 argument, but more are expected
<src/xz/xz.1>:1743 (macro BR): only 1 argument, but more are expected
<src/xz/xz.1>:1920 (macro BR): only 1 argument, but more are expected
<src/xz/xz.1>:2213 (macro BR): only 1 argument, but more are expected
Output from nroff and troff is unchanged, except for a font change of a
full stop (.).
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
DJGPP 2.05 added support for thousands separators but it's
broken at least under WinXP with Finnish locale that uses
a non-breaking space as the thousands separator. Workaround
by disabling thousands separators for DJGPP builds.
strerror() needs <string.h> which happened to be included via
tuklib_common.h -> tuklib_config.h -> sysdefs.h if HAVE_CONFIG_H
was defined. This wasn't tested without config.h before so it
had worked fine.
string.h is used unconditionally elsewhere in the project and
configure has always stopped if limits.h is missing, so these
headers must have been always available even on the weirdest
systems.
The dependency on po4a is optional. It's never required to install
the translated man pages when xz is built from a release tarball.
If po4a is missing when building from xz.git, the translated man
pages won't be generated but otherwise the build will work normally.
The translations are only updated automatically by autogen.sh and
by "make mydist". This makes it easy to keep po4a as an optional
dependency and ensures that I won't forget to put updated
translations to a release tarball.
The translated man pages aren't installed if --disable-nls is used.
The installation of translated man pages abuses Automake internals
by calling "install-man" with redefined dist_man_MANS and man_MANS.
This makes the hairy script code slightly less hairy. If it breaks
some day, this code needs to be fixed; don't blame Automake developers.
Also, this adds more quotes to the existing shell script code in
the Makefile.am "-hook"s.
See the code comment for reasoning. It's far from perfect but
hopefully good enough for certain cases while hopefully doing
nothing bad in other situations.
At presets -5 ... -9, 4020 MiB vs. 4096 MiB makes no difference
on how xz scales down the number of threads.
The limit has to be a few MiB below 4096 MiB because otherwise
things like "xz --lzma2=dict=500MiB" won't scale down the dict
size enough and xz cannot allocate enough memory. With
"ulimit -v $((4096 * 1024))" on x86-64, the limit in xz had
to be no more than 4085 MiB. Some safety margin is good though.
This is hack but it should be useful when running 32-bit xz on
a 64-bit kernel that gives full 4 GiB address space to xz.
Hopefully this is enough to solve this:
https://bugzilla.redhat.com/show_bug.cgi?id=1196786
FreeBSD has a patch that limits the result in tuklib_physmem()
to SIZE_MAX on 32-bit systems. While I think it's not the way
to do it, the results on --memlimit-compress have been good. This
commit should achieve practically identical results for compression
while leaving decompression and tuklib_physmem() and thus
lzma_physmem() unaffected.
xz --flush-timeout=2000, old version:
1. xz is started. The next flush will happen after two seconds.
2. No input for one second.
3. A burst of a few kilobytes of input.
4. No input for one second.
5. Two seconds have passed and flushing starts.
The first second counted towards the flush-timeout even though
there was no pending data. This can cause flushing to occur more
often than needed.
xz --flush-timeout=2000, after this commit:
1. xz is started.
2. No input for one second.
3. A burst of a few kilobytes of input. The next flush will
happen after two seconds counted from the time when the
first bytes of the burst were read.
4. No input for one second.
5. No input for another second.
6. Two seconds have passed and flushing starts.
The same code sequence repeats so it's nicer as a separate function.
Note that in one case there was no test for opt_mode != MODE_TEST,
but that was only because that condition would always be true, so
this commit doesn't change the behavior there.
When input blocked, xz --flush-timeout=1 would wake up every
millisecond and initiate flushing which would have nothing to
flush and thus would just waste CPU time. The fix disables the
timeout when no input has been seen since the previous flush.
Using the aligned methods requires more care to ensure that
the address really is aligned, so it's nicer if the aligned
methods are prefixed. The next commit will remove the unaligned_
prefix from the unaligned methods which in liblzma are used in
more places than the aligned ones.
Add a configure option --enable-unsafe-type-punning to get the
old non-conforming memory access methods. It can be useful with
old compilers or in some other less typical situations but
shouldn't normally be used.
Omit the packed struct trick for unaligned access. While it's
best in some cases, this is simpler. If the memcpy trick doesn't
work, one can request unsafe type punning from configure.
Because CRC32/CRC64 code needs fast aligned reads, if no very
safe way to do it is found, type punning is used as a fallback.
This sucks but since it currently works in practice, it seems to
be the least bad option. It's never needed with GCC >= 4.7 or
Clang >= 3.6 since these support __builtin_assume_aligned and
thus fast aligned access can be done with the memcpy trick.
Other things:
- Support GCC/Clang __builtin_bswapXX
- Cleaner bswap fallback macros
- Minor cleanups
This adds a configure option --enable-path-for-scripts=PREFIX
which defaults to empty except on Solaris it is /usr/xpg4/bin
to make POSIX grep and others available. The Solaris case had
been documented in INSTALL with a manual fix but it's better
to do this automatically since it is needed on most Solaris
systems anyway.
Thanks to Daniel Richard G.
Or any off_t which isn't very big (like signed 64 bit integer
that most system have). A small off_t could overflow if the
file being decompressed had long enough run of zero bytes,
which would result in corrupt output.
