1N/Aperl570delta - what's new for perl v5.7.0
1N/AThis document describes differences between the 5.6.0 release and
1N/A=head1 Security Vulnerability Closed
1N/AA potential security vulnerability in the optional suidperl component
1N/Aof Perl has been identified. suidperl is neither built nor installed
1N/Aby default. As of September the 2nd, 2000, the only known vulnerable
1N/Aplatform is Linux, most likely all Linux distributions. CERT and
1N/Avarious vendors have been alerted about the vulnerability.
1N/AThe problem was caused by Perl trying to report a suspected security
1N/Aexploit attempt using an external program,
/bin/mail. On Linux
1N/Aplatforms the
/bin/mail program had an undocumented feature which
1N/Awhen combined with suidperl gave access to a root shell, resulting in
1N/Aa serious compromise instead of reporting the exploit attempt. If you
1N/Adon't have
/bin/mail, or if you have 'safe setuid scripts', or if
1N/Asuidperl is not installed, you are safe.
1N/AThe exploit attempt reporting feature has been completely removed from
1N/Athe Perl 5.7.0 release, so that particular vulnerability isn't there
1N/Aanymore. However, further security vulnerabilities are,
1N/Aunfortunately, always possible. The suidperl code is being reviewed
1N/Aand if deemed too risky to continue to be supported, it may be
1N/Acompletely removed from future releases. In any case, suidperl should
1N/Aonly be used by security experts who know exactly what they are doing
1N/Aand why they are using suidperl instead of some other solution such as
1N/A=head1 Incompatible Changes
1N/AArrays now always interpolate into double-quoted strings:
1N/Aconstructs like "foo@bar" now always assume C<@bar> is an array,
1N/Awhether or not the compiler has seen use of C<@bar>.
1N/AThe semantics of bless(REF, REF) were unclear and until someone proves
1N/Ait to make some sense, it is forbidden.
1N/AA reference to a reference now stringify as "REF(0x81485ec)" instead
1N/Aof "SCALAR(0x81485ec)" in order to be more consistent with the return
1N/AThe very dusty examples in the eg/ directory have been removed.
1N/ASuggestions for new shiny examples welcome but the main issue is that
1N/Athe examples need to be documented, tested and (most importantly)
1N/AThe obsolete chat2 library that should never have been allowed
1N/Ato escape the laboratory has been decommissioned.
1N/AThe unimplemented POSIX regex features [[.cc.]] and [[=c=]] are still
1N/Arecognised but now cause fatal errors. The previous behaviour of
1N/Aignoring them by default and warning if requested was unacceptable
1N/Asince it, in a way, falsely promised that the features could be used.
1N/AThe (bogus) escape sequences \8 and \9 now give an optional warning
1N/A("Unrecognized escape passed through"). There is no need to \-escape
1N/Alstat(FILEHANDLE) now gives a warning because the operation makes no sense.
1N/AIn future releases this may become a fatal error.
1N/AThe long deprecated uppercase aliases for the string comparison
1N/Aoperators (EQ, NE, LT, LE, GE, GT) have now been removed.
1N/AThe regular expression captured submatches ($1, $2, ...) are now
1N/Amore consistently unset if the match fails, instead of leaving false
1N/Adata lying around in them.
1N/AThe tr///C and tr///U features have been removed and will not return;
1N/Athe interface was a mistake. Sorry about that. For similar
1N/Afunctionality, see pack('U0', ...) and pack('C0', ...).
1N/A=head1 Core Enhancements
1N/AC<perl -d:Module=arg,arg,arg> now works (previously one couldn't pass
1N/Ain multiple arguments.)
1N/Amy __PACKAGE__ $obj now works.
1N/AC<no Module;> now works even if there is no "sub unimport" in the Module.
1N/AThe numerical comparison operators return C<undef> if either operand
1N/Ais a NaN. Previously the behaviour was unspecified.
1N/AC<pack('U0a*', ...)> can now be used to force a string to UTF-8.
1N/Aprototype(\&) is now available.
1N/AThere is now an UNTIE method.
1N/A=head1 Modules and Pragmata
1N/AFile::Temp allows one to create temporary files and directories in an
1N/Aeasy, portable, and secure way.
1N/AStorable gives persistence to Perl data structures by allowing the
1N/Astorage and retrieval of Perl data to and from files in a fast and
1N/Acompact binary format.
1N/A=head2 Updated And Improved Modules and Pragmata
1N/AThe following independently supported modules have been updated to
1N/Anewer versions from CPAN: CGI, CPAN, DB_File, File::Spec, Getopt::Long,
1N/Athe podlators bundle, Pod::LaTeX, Pod::Parser, Term::ANSIColor, Test.
1N/ABug fixes and minor enhancements have been applied to B::Deparse,
1N/AData::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
1N/AMath::Complex, Math::Trig, Net::protoent, the re pragma, SelfLoader,
1N/ASys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the warnings
1N/AThe attributes::reftype() now works on tied arguments.
1N/AAutoLoader can now be disabled with C<no AutoLoader;>,
1N/AThe English module can now be used without the infamous performance
1N/A use English '-no_performance_hit';
1N/A(Assuming, of course, that one doesn't need the troublesome variables
1N/AC<$`>, C<$&>, or C<$'>.) Also, introduced C<@LAST_MATCH_START> and
1N/AC<@LAST_MATCH_END> English aliases for C<@-> and C<@+>.
1N/AFile::Find now has pre- and post-processing callbacks. It also
1N/Acorrectly changes directories when chasing symbolic links. Callbacks
1N/A(naughtily) exiting with "next;" instead of "return;" now work.
1N/AFile::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
1N/Aprototype mismatch with CORE::glob().
1N/AIPC::Open3 now allows the use of numeric file descriptors.
1N/Ause lib now works identically to @INC. Removing directories
1N/Awith 'no lib' now works.
1N/AThe Shell module now has an OO interface.
1N/A=head1 Utility Changes
1N/APerlbug is now much more robust. It also sends the bug report to
1N/AThe perlcc utility has been rewritten and its user interface (that is,
1N/Acommand line) is much more like that of the UNIX C compiler, cc.
1N/AThe xsubpp utility for extension writers now understands POD
1N/Adocumentation embedded in the *.xs files.
1N/A=head1 New Documentation
1N/Aperl56delta details the changes between the 5.005 release and the
1N/Aperldebtut is a Perl debugging tutorial.
1N/Aperlebcdic contains considerations for running Perl on EBCDIC platforms.
1N/ANote that unfortunately EBCDIC platforms that used to supported back in
1N/APerl 5.005 are still unsupported by Perl 5.7.0; the plan, however, is to
1N/Abring them back to the fold.
1N/Aperlnewmod tells about writing and submitting a new module.
1N/Aperlposix-bc explains using Perl on the POSIX-BC platform
1N/A(an EBCDIC mainframe platform).
1N/Aperlretut is a regular expression tutorial.
1N/Aperlrequick is a regular expressions quick-start guide.
1N/AYes, much quicker than perlretut.
1N/Aperlutil explains the command line utilities packaged with the Perl
1N/A=head1 Performance Enhancements
1N/Amap() that changes the size of the list should now work faster.
1N/Asort() has been changed to use mergesort internally as opposed to the
1N/Aearlier quicksort. For very small lists this may result in slightly
1N/Aslower sorting times, but in general the speedup should be at least
1N/A20%. Additional bonuses are that the worst case behaviour of sort()
1N/Ais now better (in computer science terms it now runs in time O(N log N),
1N/Aas opposed to quicksort's Theta(N**2) worst-case run time behaviour),
1N/Aand that sort() is now stable (meaning that elements with identical
1N/Akeys will stay ordered as they were before the sort).
1N/A=head1 Installation and Configuration Improvements
1N/A=head2 Generic Improvements
1N/AINSTALL now explains how you can configure Perl to use 64-bit
1N/Aintegers even on non-64-bit platforms.
1N/A(see INSTALL) and you use Configure -Dprefix=
/foo/bar and in the old
1N/APolicy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
1N/Athem will now be changed to the new prefix,
/foo/bar. (Previously
1N/Aonly $prefix changed.) If you do not like this new behaviour,
1N/Aspecify prefix, siteprefix, and vendorprefix explicitly.
1N/AA new optional location for Perl libraries, otherlibdirs, is available.
1N/AIt can be used for example for vendor add-ons without disturbing Perl's
1N/Aown library directories.
1N/AIn many platforms the vendor-supplied 'cc' is too stripped-down to
1N/Abuild Perl (basically, 'cc' doesn't do ANSI C). If this seems
1N/Ato be the case and 'cc' does not seem to be the GNU C compiler
1N/A'gcc', an automatic attempt is made to find and use 'gcc' instead.
1N/Agcc needs to closely track the operating system release to avoid
1N/Abuild problems. If Configure finds that gcc was built for a different
1N/Aoperating system release than is running, it now gives a clearly visible
1N/Awarning that there may be trouble ahead.
1N/AIf binary compatibility with the 5.005 release is not wanted, Configure
1N/Ano longer suggests including the 5.005 modules in @INC.
1N/AConfigure C<-S> can now run non-interactively.
1N/Ainstallperl now outputs everything to STDERR.
1N/A$Config{byteorder} is now computed dynamically (this is more robust
1N/Awith "fat binaries" where an executable image contains binaries for
1N/Amore than one binary platform.)
1N/A=head1 Selected Bug Fixes
1N/ASeveral debugger fixes: exit code now reflects the script exit code,
1N/Acondition C<"0"> now treated correctly, the C<d> command now checks
1N/Aline number, the C<$.> no longer gets corrupted, all debugger output now
1N/Agoes correctly to the socket if RemotePort is set.
1N/AC<*foo{FORMAT}> now works.
1N/ALexical warnings now propagating correctly between scopes.
1N/ALine renumbering with eval and C<#line> now works.
1N/AFixed numerous memory leaks, especially in eval "".
1N/AModulus of unsigned numbers now works (4063328477 % 65535 used to
1N/Areturn 27406, instead of 27047).
1N/ASome "not a number" warnings introduced in 5.6.0 eliminated to be
1N/Amore compatible with 5.005. Infinity is now recognised as a number.
1N/Aour() variables will not cause "will not stay shared" warnings.
1N/Apack "Z" now correctly terminates the string with "\0".
1N/AFix password routines which in some shadow password platforms
1N/A(
e.g. HP-UX) caused getpwent() to return every other entry.
1N/Aprintf() no longer resets the numeric locale to "C".
1N/AC<q(a\\b)> now parses correctly as C<'a\\b'>.
1N/Awithout the q L ll prefixes (assuming you are on a quad-capable platform).
1N/ARegular expressions on references and overloaded scalars now work.
1N/Ascalar() now forces scalar context even when used in void context.
1N/Asort() arguments are now compiled in the right wantarray context
1N/A(they were accidentally using the context of the sort() itself).
1N/AChanged the POSIX character class C<[[:space:]]> to include the (very
1N/Arare) vertical tab character. Added a new POSIX-ish character class
1N/AC<[[:blank:]]> which stands for horizontal whitespace (currently,
1N/Athe space and the tab).
1N/A$AUTOLOAD, sort(), lock(), and spawning subprocesses
1N/Ain multiple threads simultaneously are now thread-safe.
1N/AAllow read-only string on left hand side of non-modifying tr///.
1N/ASeveral Unicode fixes (but still not perfect).
1N/ABOMs (byte order marks) in the beginning of Perl files
1N/A(scripts, modules) should now be transparently skipped.
1N/AUTF-16 (UCS-2) encoded Perl files should now be read correctly.
1N/AThe character tables have been updated to Unicode 3.0.1.
1N/Achr() for values greater than 127 now create utf8 when under use
1N/AComparing with utf8 data does not magically upgrade non-utf8 data into
1N/AC<IsAlnum>, C<IsAlpha>, and C<IsWord> now match titlecase.
1N/AConcatenation with the C<.> operator or via variable interpolation,
1N/AC<eq>, C<substr>, C<reverse>, C<quotemeta>, the C<x> operator,
1N/Asubstitution with C<s///>, single-quoted UTF-8, should now work--in
1N/AThe C<tr///> operator now works I<slightly> better but is still rather
1N/Abroken. Note that the C<tr///CU> functionality has been removed (but
1N/Asee pack('U0', ...)).
1N/Avec() now refuses to deal with characters >255.
1N/AZero entries were missing from the Unicode classes like C<IsDigit>.
1N/AUNIVERSAL::isa no longer caches methods incorrectly. (This broke
1N/Athe Tk extension with 5.6.0.)
1N/A=head2 Platform Specific Changes and Fixes
1N/ASetting C<$0> now works (as much as possible; see perlvar for details).
1N/ANumerous updates; currently synchronised with Cygwin 1.1.4.
1N/APerl now works on post-3.0 FreeBSDs.
1N/ANumerous compilation flag and hint enhancements; accidental mixing
1N/Aof 32-bit and 64-bit libraries (a doomed attempt) made much harder.
1N/ALong doubles should now work (see INSTALL).
1N/ACompilation of the standard Perl distribution in Mac OS Classic should
1N/Anow work if you have the Metrowerks development environment and the
1N/Amissing Mac-specific toolkit bits. Contact the macperl mailing list
1N/ANow works with usethreads (see INSTALL).
1N/A64-bitness using the Sun Workshop compiler now works.
1N/ATru64 (aka Digital UNIX, aka DEC OSF/1)
1N/AThe operating system version letter now recorded in $Config{osvers}.
1N/AAllow compiling with gcc (previously explicitly forbidden). Compiling
1N/Awith gcc still not recommended because buggy code results, even with
1N/AFixed various alignment problems that lead into core dumps either
1N/Aduring build or later; no longer dies on math errors at runtime;
1N/Anow using full quad integers (64 bits), previously was using
1N/Aonly 46 bit integers for speed.
1N/Achdir() now works better despite a CRT bug; now works with MULTIPLICITY
1N/A(see INSTALL); now works with Perl's malloc.
1N/Aaccept() no longer leaks memory.
1N/ABetter chdir() return value for a non-existent directory.
1N/ANew %ENV entries now propagate to subprocesses.
1N/A$ENV{LIB} now used to search for libs under Visual C.
1N/AA failed (pseudo)fork now returns undef and sets errno to EAGAIN.
1N/AAllow REG_EXPAND_SZ keys in the registry.
1N/ACan now send() from all threads, not just the first one.
1N/AFake signal handling reenabled, bugs and all.
1N/ALess stack reserved per thread so that more threads can run
1N/Aconcurrently. (Still 16M per thread.)
1N/AC<< File::Spec->tmpdir() >> now prefers C:/temp over /tmp
1N/A(works better when perl is running as service).
1N/ABetter UNC path handling under ithreads.
1N/Await() and waitpid() now work much better.
1N/Awinsock handle leak fixed.
1N/A=head1 New or Changed Diagnostics
1N/AAll regular expression compilation error messages are now hopefully
1N/Aeasier to understand both because the error message now comes before
1N/Athe failed regex and because the point of failure is now clearly
1N/AThe various "opened only for", "on closed", "never opened" warnings
1N/Adrop the C<main::> prefix for filehandles in the C<main> package,
1N/Afor example C<STDIN> instead of <main::STDIN>.
1N/AThe "Unrecognized escape" warning has been extended to include C<\8>,
1N/AC<\9>, and C<\_>. There is no need to escape any of the C<\w> characters.
1N/A=head1 Changed Internals
1N/AYou can now build a really minimal perl called microperl.
1N/ABuilding microperl does not require even running Configure;
1N/Amany assumptions, some of which may be too bold; the resulting
1N/Aexecutable may crash or otherwise misbehave in wondrous ways.
1N/AFor careful hackers only.
1N/AAdded rsignal(), whichsig(), do_join() to the publicised API.
1N/AMade possible to propagate customised exceptions via croak()ing.
1N/AAdded is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and utf8_to_bytes().
1N/ANow xsubs can have attributes just like subs.
1N/A=head1 Known Problems
1N/A=head2 Unicode Support Still Far From Perfect
1N/AWe're working on it. Stay tuned.
1N/A=head2 EBCDIC Still A Lost Platform
1N/AThe plan is to bring them back.
1N/A=head2 Building Extensions Can Fail Because Of Largefiles
1N/ACertain extensions like mod_perl and BSD::Resource are known to have
1N/Aissues with `largefiles', a change brought by Perl 5.6.0 in which file
1N/Aoffsets default to 64 bits wide, where supported. Modules may fail to
1N/Acompile at all or compile and work incorrectly. Currently there is no
1N/Agood solution for the problem, but Configure now provides appropriate
1N/Anon-largefile ccflags, ldflags, libswanted, and libs in the %Config
1N/Ahash (
e.g., $Config{ccflags_nolargefiles}) so the extensions that are
1N/Ahaving problems can try configuring themselves without the
1N/Alargefileness. This is admittedly not a clean solution, and the
1N/Asolution may not even work at all. One potential failure is whether
1N/Aone can (or, if one can, whether it's a good idea) link together at
1N/Aall binaries with different ideas about file offsets, all this is
1N/A=head2 ftmp-security tests warn 'system possibly insecure'
1N/ADon't panic. Read INSTALL 'make test' section instead.
1N/A=head2 Test
lib/posix Subtest 9 Fails In LP64-Configured HP-UX
1N/AIf perl is configured with -Duse64bitall, the successful result of the
1N/Asubtest 10 of
lib/posix may arrive before the successful result of the
1N/Asubtest 9, which confuses the test harness so much that it thinks the
1N/A=head2 Long Doubles Still Don't Work In Solaris
1N/AThe experimental long double support is still very much so in Solaris.
1N/A(Other platforms like Linux and Tru64 are beginning to solidify in
1N/A=head2 Storable tests fail in some platforms
1N/AIf any Storable tests fail the use of Storable is not advisable.
1N/AMany Storable tests fail on AIX configured with 64 bit integers.
1N/ASo far unidentified problems break Storable in AIX if Perl is
1N/Aconfigured to use 64 bit integers. AIX in 32-bit mode works and
1N/Aother 64-bit platforms work with Storable.
1N/ADOS DJGPP may hang when testing Storable.
1N/AThis means that you cannot read old (pre-Storable-0.7) Storable images
1N/Amade in other platforms.
1N/Ast-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS Alpha 7.2.
1N/A=head2 Threads Are Still Experimental
1N/AMultithreading is still an experimental feature. Some platforms
1N/A # This is a KNOWN FAILURE, and one of the reasons why threading
1N/A # is still an experimental feature. It is here to stop people
1N/A # from deploying threads in production. ;-)
1N/Aand another known thread-related warning is
1N/A panic: magic_mutexfree during global destruction.
1N/A panic: magic_mutexfree during global destruction.
1N/A panic: magic_mutexfree during global destruction.
1N/A=head2 The Compiler Suite Is Still Experimental
1N/AThe compiler suite is slowly getting better but is nowhere near
1N/Aworking order yet. The backend part that has seen perhaps the most
1N/Aprogress is the bytecode compiler.
1N/A=head1 Reporting Bugs
1N/AIf you find what you think is a bug, you might check the articles
1N/AIf you believe you have an unreported bug, please run the B<perlbug>
1N/Aprogram included with your release. Be sure to trim your bug down
1N/Ato a tiny but sufficient test case. Your bug report, along with the
1N/Aoutput of C<perl -V>, will be sent off to perlbug@perl.org to be
1N/Aanalysed by the Perl porting team.
1N/AThe F<Changes> file for exhaustive details on what changed.
1N/AThe F<INSTALL> file for how to build Perl.
1N/AThe F<README> file for general stuff.
1N/AThe F<Artistic> and F<Copying> files for copyright information.
1N/AWritten by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
1N/Afrom The Perl Porters and Perl Users submitting feedback and patches.
1N/ASend omissions or corrections to <F<perlbug@perl.org>>.