perl570delta - what's new for perl v5.7.0 |
perl570delta - what's new for perl v5.7.0
This document describes differences between the 5.6.0 release and the 5.7.0 release.
A potential security vulnerability in the optional suidperl component of Perl has been identified. suidperl is neither built nor installed by default. As of September the 2nd, 2000, the only known vulnerable platform is Linux, most likely all Linux distributions. CERT and various vendors have been alerted about the vulnerability.
The problem was caused by Perl trying to report a suspected security exploit attempt using an external program, /bin/mail. On Linux platforms the /bin/mail program had an undocumented feature which when combined with suidperl gave access to a root shell, resulting in a serious compromise instead of reporting the exploit attempt. If you don't have /bin/mail, or if you have 'safe setuid scripts', or if suidperl is not installed, you are safe.
The exploit attempt reporting feature has been completely removed from the Perl 5.7.0 release, so that particular vulnerability isn't there anymore. However, further security vulnerabilities are, unfortunately, always possible. The suidperl code is being reviewed and if deemed too risky to continue to be supported, it may be completely removed from future releases. In any case, suidperl should only be used by security experts who know exactly what they are doing and why they are using suidperl instead of some other solution such as sudo ( see http://www.courtesan.com/sudo/ ).
@bar
is an array,
whether or not the compiler has seen use of @bar
.
The semantics of bless(REF, REF) were unclear and until someone proves
it to make some sense, it is forbidden.
A reference to a reference now stringify as ``REF(0x81485ec)'' instead
of ``SCALAR(0x81485ec)'' in order to be more consistent with the return
value of ref().
The very dusty examples in the eg/ directory have been removed.
Suggestions for new shiny examples welcome but the main issue is that
the examples need to be documented, tested and (most importantly)
maintained.
The obsolete chat2 library that should never have been allowed
to escape the laboratory has been decommissioned.
The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
recognised but now cause fatal errors. The previous behaviour of
ignoring them by default and warning if requested was unacceptable
since it, in a way, falsely promised that the features could be used.
The (bogus) escape sequences \8 and \9 now give an optional warning
(``Unrecognized escape passed through''). There is no need to \-escape
any \w
character.
lstat(FILEHANDLE)
now gives a warning because the operation makes no sense.
In future releases this may become a fatal error.
The long deprecated uppercase aliases for the string comparison
operators (EQ, NE, LT, LE, GE, GT) have now been removed.
The regular expression captured submatches ($1, $2, ...) are now
more consistently unset if the match fails, instead of leaving false
data lying around in them.
The tr///C and tr///U features have been removed and will not return;
the interface was a mistake. Sorry about that. For similar
functionality, see pack('U0', ...) and pack('C0', ...).
perl -d:Module=arg,arg,arg
now works (previously one couldn't pass
in multiple arguments.)
my __PACKAGE__ $obj now works.
no Module;
now works even if there is no ``sub unimport'' in the Module.
The numerical comparison operators return undef
if either operand
is a NaN. Previously the behaviour was unspecified.
pack('U0a*', ...)
can now be used to force a string to UTF-8.
prototype(\&)
is now available.
There is now an UNTIE method.
no AutoLoader;
,
The English module can now be used without the infamous performance
hit by saying
use English '-no_performance_hit';
(Assuming, of course, that one doesn't need the troublesome variables
$`
, $&
, or $'
.) Also, introduced @LAST_MATCH_START
and
@LAST_MATCH_END
English aliases for @-
and @+
.
%INC
now localised in a Safe compartment so that use/require work.
The Shell module now has an OO interface.
map()
that changes the size of the list should now work faster.
sort()
has been changed to use mergesort internally as opposed to the
earlier quicksort. For very small lists this may result in slightly
slower sorting times, but in general the speedup should be at least
20%. Additional bonuses are that the worst case behaviour of sort()
is now better (in computer science terms it now runs in time O(N log N),
as opposed to quicksort's Theta(N**2)
worst-case run time behaviour),
and that sort()
is now stable (meaning that elements with identical
keys will stay ordered as they were before the sort).
-S
can now run non-interactively.
configure.gnu now works with options with whitespace in them.
installperl now outputs everything to STDERR.
$Config{byteorder} is now computed dynamically (this is more robust
with ``fat binaries'' where an executable image contains binaries for
more than one binary platform.)
"0"
now treated correctly, the d
command now checks
line number, the $.
no longer gets corrupted, all debugger output now
goes correctly to the socket if RemotePort is set.
*foo{FORMAT}
now works.
Lexical warnings now propagating correctly between scopes.
Line renumbering with eval and #line
now works.
Fixed numerous memory leaks, especially in eval ``''.
Modulus of unsigned numbers now works (4063328477 % 65535 used to
return 27406, instead of 27047).
Some ``not a number'' warnings introduced in 5.6.0 eliminated to be
more compatible with 5.005. Infinity is now recognised as a number.
our()
variables will not cause ``will not stay shared'' warnings.
pack ``Z'' now correctly terminates the string with ``\0''.
Fix password routines which in some shadow password platforms
(e.g. HP-UX) caused getpwent()
to return every other entry.
printf()
no longer resets the numeric locale to ``C''.
q(a\\b)
now parses correctly as 'a\\b'
.
Printing quads (64-bit integers) with printf/sprintf now works
without the q L ll prefixes (assuming you are on a quad-capable platform).
Regular expressions on references and overloaded scalars now work.
scalar()
now forces scalar context even when used in void context.
sort()
arguments are now compiled in the right wantarray context
(they were accidentally using the context of the sort()
itself).
Changed the POSIX character class [[:space:]]
to include the (very
rare) vertical tab character. Added a new POSIX-ish character class
[[:blank:]]
which stands for horizontal whitespace (currently,
the space and the tab).
$AUTOLOAD, sort(), lock(), and spawning subprocesses
in multiple threads simultaneously are now thread-safe.
Allow read-only string on left hand side of non-modifying tr///.
Several Unicode fixes (but still not perfect).
chr()
for values greater than 127 now create utf8 when under use
utf8.
Comparing with utf8 data does not magically upgrade non-utf8 data into
utf8.
IsAlnum
, IsAlpha
, and IsWord
now match titlecase.
Concatenation with the .
operator or via variable interpolation,
eq
, substr
, reverse
, quotemeta
, the x
operator,
substitution with s///
, single-quoted UTF-8, should now work--in
theory.
The tr///
operator now works slightly better but is still rather
broken. Note that the tr///CU
functionality has been removed (but
see pack('U0', ...)).
vec()
now refuses to deal with characters >255.
Zero entries were missing from the Unicode classes like IsDigit
.
Perl now works on post-4.0 BSD/OSes.
All BSDsSetting $0
now works (as much as possible; see perlvar for details).
Numerous updates; currently synchronised with Cygwin 1.1.4.
EPOCEPOC update after Perl 5.6.0. See README.epoc.
FreeBSD 3.*Perl now works on post-3.0 FreeBSDs.
HP-UXREADME.hpux updated; Configure -Duse64bitall
now almost works.
Numerous compilation flag and hint enhancements; accidental mixing of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
LinuxLong doubles should now work (see INSTALL).
Mac OS ClassicCompilation of the standard Perl distribution in Mac OS Classic should now work if you have the Metrowerks development environment and the missing Mac-specific toolkit bits. Contact the macperl mailing list for details.
MPE/iXMPE/iX update after Perl 5.6.0. See README.mpeix.
NetBSD/sparcPerl now works on NetBSD/sparc.
OS/2Now works with usethreads (see INSTALL).
Solaris64-bitness using the Sun Workshop compiler now works.
Tru64 (aka Digital UNIX, aka DEC OSF/1)The operating system version letter now recorded in $Config{osvers}. Allow compiling with gcc (previously explicitly forbidden). Compiling with gcc still not recommended because buggy code results, even with gcc 2.95.2.
UnicosFixed various alignment problems that lead into core dumps either during build or later; no longer dies on math errors at runtime; now using full quad integers (64 bits), previously was using only 46 bit integers for speed.
VMSchdir()
now works better despite a CRT bug; now works with MULTIPLICITY
(see INSTALL); now works with Perl's malloc.
accept()
no longer leaks memory.
Better chdir()
return value for a non-existent directory.
New %ENV entries now propagate to subprocesses.
$ENV{LIB} now used to search for libs under Visual C.
A failed (pseudo)fork now returns undef and sets errno to EAGAIN.
Allow REG_EXPAND_SZ keys in the registry.
Can now send()
from all threads, not just the first one.
Fake signal handling reenabled, bugs and all.
Less stack reserved per thread so that more threads can run
concurrently. (Still 16M per thread.)
File::Spec->tmpdir()
now prefers C:/temp over /tmp
(works better when perl is running as service).
Better UNC path handling under ithreads.
wait()
and waitpid()
now work much better.
winsock handle leak fixed.
All regular expression compilation error messages are now hopefully easier to understand both because the error message now comes before the failed regex and because the point of failure is now clearly marked.
The various ``opened only for'', ``on closed'', ``never opened'' warnings
drop the main::
prefix for filehandles in the main
package,
for example STDIN
instead of <main::STDIN>.
The ``Unrecognized escape'' warning has been extended to include \8
,
\9
, and \_
. There is no need to escape any of the \w
characters.
make -f Makefile.micro
should be enough. Beware: microperl makes
many assumptions, some of which may be too bold; the resulting
executable may crash or otherwise misbehave in wondrous ways.
For careful hackers only.
Added rsignal(), whichsig(), do_join()
to the publicised API.
Made possible to propagate customised exceptions via croak()ing.
Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
Now xsubs can have attributes just like subs.
We're working on it. Stay tuned.
The plan is to bring them back.
Certain extensions like mod_perl and BSD::Resource are known to have issues with `largefiles', a change brought by Perl 5.6.0 in which file offsets default to 64 bits wide, where supported. Modules may fail to compile at all or compile and work incorrectly. Currently there is no good solution for the problem, but Configure now provides appropriate non-largefile ccflags, ldflags, libswanted, and libs in the %Config hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are having problems can try configuring themselves without the largefileness. This is admittedly not a clean solution, and the solution may not even work at all. One potential failure is whether one can (or, if one can, whether it's a good idea) link together at all binaries with different ideas about file offsets, all this is platform-dependent.
Don't panic. Read INSTALL 'make test' section instead.
If perl is configured with -Duse64bitall, the successful result of the subtest 10 of lib/posix may arrive before the successful result of the subtest 9, which confuses the test harness so much that it thinks the subtest 9 failed.
The experimental long double support is still very much so in Solaris. (Other platforms like Linux and Tru64 are beginning to solidify in this area.)
No known fix.
If any Storable tests fail the use of Storable is not advisable.
So far unidentified problems break Storable in AIX if Perl is configured to use 64 bit integers. AIX in 32-bit mode works and other 64-bit platforms work with Storable.
DOS DJGPP may hang when testing Storable. st-06compat fails in UNICOS and UNICOS/mk.This means that you cannot read old (pre-Storable-0.7) Storable images made in other platforms.
st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS Alpha 7.2.
Multithreading is still an experimental feature. Some platforms emit the following message for lib/thr5005
# # This is a KNOWN FAILURE, and one of the reasons why threading # is still an experimental feature. It is here to stop people # from deploying threads in production. ;-) #
and another known thread-related warning is
pragma/overload......Unbalanced saves: 3 more saves than restores panic: magic_mutexfree during global destruction. ok lib/selfloader.......Unbalanced saves: 3 more saves than restores panic: magic_mutexfree during global destruction. ok lib/st-dclone........Unbalanced saves: 3 more saves than restores panic: magic_mutexfree during global destruction. ok
The compiler suite is slowly getting better but is nowhere near working order yet. The backend part that has seen perhaps the most progress is the bytecode compiler.
If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at http://bugs.perl.org/ There may also be information at http://www.perl.com/perl/ , the Perl Home Page.
If you believe you have an unreported bug, please run the perlbug
program included with your release. Be sure to trim your bug down
to a tiny but sufficient test case. Your bug report, along with the
output of perl -V
, will be sent off to perlbug@perl.org to be
analysed by the Perl porting team.
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
Written by Jarkko Hietaniemi <jhi@iki.fi>, with many contributions from The Perl Porters and Perl Users submitting feedback and patches.
Send omissions or corrections to <perlbug@perl.org>.
perl570delta - what's new for perl v5.7.0 |