1PERL570DELTA(1) Perl Programmers Reference Guide PERL570DELTA(1)
2
6 perl570delta - what's new for perl v5.7.0
7
9 This document describes differences between the 5.6.0 release and the
10 5.7.0 release.
11
13 A potential security vulnerability in the optional suidperl component
14 of Perl has been identified. suidperl is neither built nor installed
15 by default. As of September the 2nd, 2000, the only known vulnerable
16 platform is Linux, most likely all Linux distributions. CERT and
17 various vendors have been alerted about the vulnerability.
18 The problem was caused by Perl trying to report a suspected security
20 exploit attempt using an external program, /bin/mail. On Linux
21 platforms the /bin/mail program had an undocumented feature which when
22 combined with suidperl gave access to a root shell, resulting in a
23 serious compromise instead of reporting the exploit attempt. If you
24 don't have /bin/mail, or if you have 'safe setuid scripts', or if
25 suidperl is not installed, you are safe.
26 The exploit attempt reporting feature has been completely removed from
28 the Perl 5.7.0 release, so that particular vulnerability isn't there
29 anymore. However, further security vulnerabilities are, unfortunately,
30 always possible. The suidperl code is being reviewed and if deemed too
31 risky to continue to be supported, it may be completely removed from
32 future releases. In any case, suidperl should only be used by security
33 experts who know exactly what they are doing and why they are using
34 suidperl instead of some other solution such as sudo ( see
35 http://www.courtesan.com/sudo/ ).
36
38 · Arrays now always interpolate into double-quoted strings:
39 constructs like "foo@bar" now always assume @bar is an array,
40 whether or not the compiler has seen use of @bar.
41 · The semantics of bless(REF, REF) were unclear and until someone
43 proves it to make some sense, it is forbidden.
44 · A reference to a reference now stringify as "REF(0x81485ec)"
46 instead of "SCALAR(0x81485ec)" in order to be more consistent with
47 the return value of ref().
48 · The very dusty examples in the eg/ directory have been removed.
50 Suggestions for new shiny examples welcome but the main issue is
51 that the examples need to be documented, tested and (most
52 importantly) maintained.
53 · The obsolete chat2 library that should never have been allowed to
55 escape the laboratory has been decommissioned.
56 · The unimplemented POSIX regex features [[.cc.]] and [[=c=]] are
58 still recognised but now cause fatal errors. The previous
59 behaviour of ignoring them by default and warning if requested was
60 unacceptable since it, in a way, falsely promised that the features
61 could be used.
62 · The (bogus) escape sequences \8 and \9 now give an optional warning
64 ("Unrecognized escape passed through"). There is no need to
65 \-escape any "\w" character.
66 · lstat(FILEHANDLE) now gives a warning because the operation makes
68 no sense. In future releases this may become a fatal error.
69 · The long deprecated uppercase aliases for the string comparison
71 operators (EQ, NE, LT, LE, GE, GT) have now been removed.
72 · The regular expression captured submatches ($1, $2, ...) are now
74 more consistently unset if the match fails, instead of leaving
75 false data lying around in them.
76 · The tr///C and tr///U features have been removed and will not
78 return; the interface was a mistake. Sorry about that. For
79 similar functionality, see pack('U0', ...) and pack('C0', ...).
80
82 · "perl -d:Module=arg,arg,arg" now works (previously one couldn't
83 pass in multiple arguments.)
84 · my __PACKAGE__ $obj now works.
86 · "no Module;" now works even if there is no "sub unimport" in the
88 Module.
89 · The numerical comparison operators return "undef" if either operand
91 is a NaN. Previously the behaviour was unspecified.
92 · "pack('U0a*', ...)" can now be used to force a string to UTF-8.
94 · prototype(\&) is now available.
96 · There is now an UNTIE method.
98
100 New Modules
101 · File::Temp allows one to create temporary files and directories in
102 an easy, portable, and secure way.
103 · Storable gives persistence to Perl data structures by allowing the
105 storage and retrieval of Perl data to and from files in a fast and
106 compact binary format.
107 Updated And Improved Modules and Pragmata
109 · The following independently supported modules have been updated to
110 newer versions from CPAN: CGI, CPAN, DB_File, File::Spec,
111 Getopt::Long, the podlators bundle, Pod::LaTeX, Pod::Parser,
112 Term::ANSIColor, Test.
113 · Bug fixes and minor enhancements have been applied to B::Deparse,
115 Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
116 Math::Complex, Math::Trig, Net::protoent, the re pragma,
117 SelfLoader, Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and
118 the warnings pragma.
119 · The attributes::reftype() now works on tied arguments.
121 · AutoLoader can now be disabled with "no AutoLoader;",
123 · The English module can now be used without the infamous performance
125 hit by saying
126 use English '-no_performance_hit';
128 (Assuming, of course, that one doesn't need the troublesome
130 variables "$`", $&, or "$'".) Also, introduced @LAST_MATCH_START
131 and @LAST_MATCH_END English aliases for "@-" and "@+".
132 · File::Find now has pre- and post-processing callbacks. It also
134 correctly changes directories when chasing symbolic links.
135 Callbacks (naughtily) exiting with "next;" instead of "return;" now
136 work.
137 · File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid
139 prototype mismatch with CORE::glob().
140 · IPC::Open3 now allows the use of numeric file descriptors.
142 · use lib now works identically to @INC. Removing directories with
144 'no lib' now works.
145 · %INC now localised in a Safe compartment so that use/require work.
147 · The Shell module now has an OO interface.
149
151 · The Emacs perl mode (emacs/cperl-mode.el) has been updated to
152 version 4.31.
153 · Perlbug is now much more robust. It also sends the bug report to
155 perl.org, not perl.com.
156 · The perlcc utility has been rewritten and its user interface (that
158 is, command line) is much more like that of the UNIX C compiler,
159 cc.
160 · The xsubpp utility for extension writers now understands POD
162 documentation embedded in the *.xs files.
163
165 · perl56delta details the changes between the 5.005 release and the
166 5.6.0 release.
167 · perldebtut is a Perl debugging tutorial.
169 · perlebcdic contains considerations for running Perl on EBCDIC
171 platforms. Note that unfortunately EBCDIC platforms that used to
172 supported back in Perl 5.005 are still unsupported by Perl 5.7.0;
173 the plan, however, is to bring them back to the fold.
174 · perlnewmod tells about writing and submitting a new module.
176 · perlposix-bc explains using Perl on the POSIX-BC platform (an
178 EBCDIC mainframe platform).
179 · perlretut is a regular expression tutorial.
181 · perlrequick is a regular expressions quick-start guide. Yes, much
183 quicker than perlretut.
184 · perlutil explains the command line utilities packaged with the Perl
186 distribution.
187
189 · map() that changes the size of the list should now work faster.
190 · sort() has been changed to use mergesort internally as opposed to
192 the earlier quicksort. For very small lists this may result in
193 slightly slower sorting times, but in general the speedup should be
194 at least 20%. Additional bonuses are that the worst case behaviour
195 of sort() is now better (in computer science terms it now runs in
196 time O(N log N), as opposed to quicksort's Theta(N**2) worst-case
197 run time behaviour), and that sort() is now stable (meaning that
198 elements with identical keys will stay ordered as they were before
199 the sort).
200
202 Generic Improvements
203 · INSTALL now explains how you can configure Perl to use 64-bit
204 integers even on non-64-bit platforms.
205 · Policy.sh policy change: if you are reusing a Policy.sh file (see
207 INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
208 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
209 them will now be changed to the new prefix, /foo/bar. (Previously
210 only $prefix changed.) If you do not like this new behaviour,
211 specify prefix, siteprefix, and vendorprefix explicitly.
212 · A new optional location for Perl libraries, otherlibdirs, is
214 available. It can be used for example for vendor add-ons without
215 disturbing Perl's own library directories.
216 · In many platforms the vendor-supplied 'cc' is too stripped-down to
218 build Perl (basically, 'cc' doesn't do ANSI C). If this seems to
219 be the case and 'cc' does not seem to be the GNU C compiler 'gcc',
220 an automatic attempt is made to find and use 'gcc' instead.
221 · gcc needs to closely track the operating system release to avoid
223 build problems. If Configure finds that gcc was built for a
224 different operating system release than is running, it now gives a
225 clearly visible warning that there may be trouble ahead.
226 · If binary compatibility with the 5.005 release is not wanted,
228 Configure no longer suggests including the 5.005 modules in @INC.
229 · Configure "-S" can now run non-interactively.
231 · configure.gnu now works with options with whitespace in them.
233 · installperl now outputs everything to STDERR.
235 · $Config{byteorder} is now computed dynamically (this is more robust
237 with "fat binaries" where an executable image contains binaries for
238 more than one binary platform.)
239
241 · Several debugger fixes: exit code now reflects the script exit
242 code, condition "0" now treated correctly, the "d" command now
243 checks line number, the $. no longer gets corrupted, all debugger
244 output now goes correctly to the socket if RemotePort is set.
245 · *foo{FORMAT} now works.
247 · Lexical warnings now propagating correctly between scopes.
249 · Line renumbering with eval and "#line" now works.
251 · Fixed numerous memory leaks, especially in eval "".
253 · Modulus of unsigned numbers now works (4063328477 % 65535 used to
255 return 27406, instead of 27047).
256 · Some "not a number" warnings introduced in 5.6.0 eliminated to be
258 more compatible with 5.005. Infinity is now recognised as a
259 number.
260 · our() variables will not cause "will not stay shared" warnings.
262 · pack "Z" now correctly terminates the string with "\0".
264 · Fix password routines which in some shadow password platforms (e.g.
266 HP-UX) caused getpwent() to return every other entry.
267 · printf() no longer resets the numeric locale to "C".
269 · "q(a\\b)" now parses correctly as 'a\\b'.
271 · Printing quads (64-bit integers) with printf/sprintf now works
273 without the q L ll prefixes (assuming you are on a quad-capable
274 platform).
275 · Regular expressions on references and overloaded scalars now work.
277 · scalar() now forces scalar context even when used in void context.
279 · sort() arguments are now compiled in the right wantarray context
281 (they were accidentally using the context of the sort() itself).
282 · Changed the POSIX character class "[[:space:]]" to include the
284 (very rare) vertical tab character. Added a new POSIX-ish
285 character class "[[:blank:]]" which stands for horizontal
286 whitespace (currently, the space and the tab).
287 · $AUTOLOAD, sort(), lock(), and spawning subprocesses in multiple
289 threads simultaneously are now thread-safe.
290 · Allow read-only string on left hand side of non-modifying tr///.
292 · Several Unicode fixes (but still not perfect).
294 · BOMs (byte order marks) in the beginning of Perl files
296 (scripts, modules) should now be transparently skipped.
297 UTF-16 (UCS-2) encoded Perl files should now be read
298 correctly.
299 · The character tables have been updated to Unicode 3.0.1.
301 · chr() for values greater than 127 now create utf8 when
303 under use utf8.
304 · Comparing with utf8 data does not magically upgrade
306 non-utf8 data into utf8.
307 · "IsAlnum", "IsAlpha", and "IsWord" now match titlecase.
309 · Concatenation with the "." operator or via variable
311 interpolation, "eq", "substr", "reverse", "quotemeta", the
312 "x" operator, substitution with "s///", single-quoted
313 UTF-8, should now work--in theory.
314 · The "tr///" operator now works slightly better but is still
316 rather broken. Note that the "tr///CU" functionality has
317 been removed (but see pack('U0', ...)).
318 · vec() now refuses to deal with characters >255.
320 · Zero entries were missing from the Unicode classes like
322 "IsDigit".
323 · UNIVERSAL::isa no longer caches methods incorrectly. (This broke
325 the Tk extension with 5.6.0.)
326 Platform Specific Changes and Fixes
328 · BSDI 4.*
329 Perl now works on post-4.0 BSD/OSes.
331 · All BSDs
333 Setting $0 now works (as much as possible; see perlvar for
335 details).
336 · Cygwin
338 Numerous updates; currently synchronised with Cygwin 1.1.4.
340 · EPOC
342 EPOC update after Perl 5.6.0. See README.epoc.
344 · FreeBSD 3.*
346 Perl now works on post-3.0 FreeBSDs.
348 · HP-UX
350 README.hpux updated; "Configure -Duse64bitall" now almost works.
352 · IRIX
354 Numerous compilation flag and hint enhancements; accidental mixing
356 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
357 · Linux
359 Long doubles should now work (see INSTALL).
361 · Mac OS Classic
363 Compilation of the standard Perl distribution in Mac OS Classic
365 should now work if you have the Metrowerks development environment
366 and the missing Mac-specific toolkit bits. Contact the macperl
367 mailing list for details.
368 · MPE/iX
370 MPE/iX update after Perl 5.6.0. See README.mpeix.
372 · NetBSD/sparc
374 Perl now works on NetBSD/sparc.
376 · OS/2
378 Now works with usethreads (see INSTALL).
380 · Solaris
382 64-bitness using the Sun Workshop compiler now works.
384 · Tru64 (aka Digital UNIX, aka DEC OSF/1)
386 The operating system version letter now recorded in
388 $Config{osvers}. Allow compiling with gcc (previously explicitly
389 forbidden). Compiling with gcc still not recommended because buggy
390 code results, even with gcc 2.95.2.
391 · Unicos
393 Fixed various alignment problems that lead into core dumps either
395 during build or later; no longer dies on math errors at runtime;
396 now using full quad integers (64 bits), previously was using only
397 46 bit integers for speed.
398 · VMS
400 chdir() now works better despite a CRT bug; now works with
402 MULTIPLICITY (see INSTALL); now works with Perl's malloc.
403 · Windows
405 · accept() no longer leaks memory.
407 · Better chdir() return value for a non-existent directory.
409 · New %ENV entries now propagate to subprocesses.
411 · $ENV{LIB} now used to search for libs under Visual C.
413 · A failed (pseudo)fork now returns undef and sets errno to
415 EAGAIN.
416 · Allow REG_EXPAND_SZ keys in the registry.
418 · Can now send() from all threads, not just the first one.
420 · Fake signal handling reenabled, bugs and all.
422 · Less stack reserved per thread so that more threads can run
424 concurrently. (Still 16M per thread.)
425 · "File::Spec->tmpdir()" now prefers C:/temp over /tmp (works
427 better when perl is running as service).
428 · Better UNC path handling under ithreads.
430 · wait() and waitpid() now work much better.
432 · winsock handle leak fixed.
434
436 All regular expression compilation error messages are now hopefully
437 easier to understand both because the error message now comes before
438 the failed regex and because the point of failure is now clearly
439 marked.
440 The various "opened only for", "on closed", "never opened" warnings
442 drop the "main::" prefix for filehandles in the "main" package, for
443 example "STDIN" instead of <main::STDIN>.
444 The "Unrecognized escape" warning has been extended to include "\8",
446 "\9", and "\_". There is no need to escape any of the "\w" characters.
447
449 · perlapi.pod (a companion to perlguts) now attempts to document the
450 internal API.
451 · You can now build a really minimal perl called microperl. Building
453 microperl does not require even running Configure; "make -f
454 Makefile.micro" should be enough. Beware: microperl makes many
455 assumptions, some of which may be too bold; the resulting
456 executable may crash or otherwise misbehave in wondrous ways. For
457 careful hackers only.
458 · Added rsignal(), whichsig(), do_join() to the publicised API.
460 · Made possible to propagate customised exceptions via croak()ing.
462 · Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and
464 utf8_to_bytes().
465 · Now xsubs can have attributes just like subs.
467
469 Unicode Support Still Far From Perfect
470 We're working on it. Stay tuned.
471 EBCDIC Still A Lost Platform
473 The plan is to bring them back.
474 Building Extensions Can Fail Because Of Largefiles
476 Certain extensions like mod_perl and BSD::Resource are known to have
477 issues with `largefiles', a change brought by Perl 5.6.0 in which file
478 offsets default to 64 bits wide, where supported. Modules may fail to
479 compile at all or compile and work incorrectly. Currently there is no
480 good solution for the problem, but Configure now provides appropriate
481 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
482 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
483 having problems can try configuring themselves without the
484 largefileness. This is admittedly not a clean solution, and the
485 solution may not even work at all. One potential failure is whether
486 one can (or, if one can, whether it's a good idea) link together at all
487 binaries with different ideas about file offsets, all this is platform-
488 dependent.
489 ftmp-security tests warn 'system possibly insecure'
491 Don't panic. Read INSTALL 'make test' section instead.
492 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
494 If perl is configured with -Duse64bitall, the successful result of the
495 subtest 10 of lib/posix may arrive before the successful result of the
496 subtest 9, which confuses the test harness so much that it thinks the
497 subtest 9 failed.
498 Long Doubles Still Don't Work In Solaris
500 The experimental long double support is still very much so in Solaris.
501 (Other platforms like Linux and Tru64 are beginning to solidify in this
502 area.)
503 Linux With Sfio Fails op/misc Test 48
505 No known fix.
506 Storable tests fail in some platforms
508 If any Storable tests fail the use of Storable is not advisable.
509 · Many Storable tests fail on AIX configured with 64 bit integers.
511 So far unidentified problems break Storable in AIX if Perl is
513 configured to use 64 bit integers. AIX in 32-bit mode works and
514 other 64-bit platforms work with Storable.
515 · DOS DJGPP may hang when testing Storable.
517 · st-06compat fails in UNICOS and UNICOS/mk.
519 This means that you cannot read old (pre-Storable-0.7) Storable
521 images made in other platforms.
522 · st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS
524 Alpha 7.2.
525 Threads Are Still Experimental
527 Multithreading is still an experimental feature. Some platforms emit
528 the following message for lib/thr5005
529 #
531 # This is a KNOWN FAILURE, and one of the reasons why threading
532 # is still an experimental feature. It is here to stop people
533 # from deploying threads in production. ;-)
534 #
535 and another known thread-related warning is
537 pragma/overload......Unbalanced saves: 3 more saves than restores
539 panic: magic_mutexfree during global destruction.
540 ok
541 lib/selfloader.......Unbalanced saves: 3 more saves than restores
542 panic: magic_mutexfree during global destruction.
543 ok
544 lib/st-dclone........Unbalanced saves: 3 more saves than restores
545 panic: magic_mutexfree during global destruction.
546 ok
547 The Compiler Suite Is Still Experimental
549 The compiler suite is slowly getting better but is nowhere near working
550 order yet. The backend part that has seen perhaps the most progress is
551 the bytecode compiler.
552
554 If you find what you think is a bug, you might check the articles
555 recently posted to the comp.lang.perl.misc newsgroup and the perl bug
556 database at http://bugs.perl.org/ There may also be information at
557 http://www.perl.com/perl/ , the Perl Home Page.
558 If you believe you have an unreported bug, please run the perlbug
560 program included with your release. Be sure to trim your bug down to a
561 tiny but sufficient test case. Your bug report, along with the output
562 of "perl -V", will be sent off to perlbug@perl.org to be analysed by
563 the Perl porting team.
564
566 The Changes file for exhaustive details on what changed.
567 The INSTALL file for how to build Perl.
569 The README file for general stuff.
571 The Artistic and Copying files for copyright information.
573
575 Written by Jarkko Hietaniemi <jhi@iki.fi>, with many contributions from
576 The Perl Porters and Perl Users submitting feedback and patches.
577 Send omissions or corrections to <perlbug@perl.org>.
579perl v5.10.1 2009-02-12 PERL570DELTA(1)