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 vari‐
17 ous 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 plat‐
21 forms the /bin/mail program had an undocumented feature which when com‐
22 bined with suidperl gave access to a root shell, resulting in a serious
23 compromise instead of reporting the exploit attempt. If you don't have
24 /bin/mail, or if you have 'safe setuid scripts', or if suidperl is not
25 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: con‐
39 structs like "foo@bar" now always assume @bar is an array, whether
40 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 impor‐
52 tantly) 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 behav‐
59 iour of ignoring them by default and warning if requested was unac‐
60 ceptable 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 simi‐
79 lar 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
103 an easy, portable, and secure way.
104 · Storable gives persistence to Perl data structures by allowing the
106 storage and retrieval of Perl data to and from files in a fast and
107 compact binary format.
108 Updated And Improved Modules and Pragmata
110 · The following independently supported modules have been updated to
112 newer versions from CPAN: CGI, CPAN, DB_File, File::Spec,
113 Getopt::Long, the podlators bundle, Pod::LaTeX, Pod::Parser,
114 Term::ANSIColor, Test.
115 · Bug fixes and minor enhancements have been applied to B::Deparse,
117 Data::Dumper, IO::Poll, IO::Socket::INET, Math::BigFloat,
118 Math::Complex, Math::Trig, Net::protoent, the re pragma, Self‐
119 Loader, Sys::SysLog, Test::Harness, Text::Wrap, UNIVERSAL, and the
120 warnings pragma.
121 · The attributes::reftype() now works on tied arguments.
123 · AutoLoader can now be disabled with "no AutoLoader;",
125 · The English module can now be used without the infamous performance
127 hit by saying
128 use English '-no_performance_hit';
130 (Assuming, of course, that one doesn't need the troublesome vari‐
132 ables $`, $&, or $'.) Also, introduced @LAST_MATCH_START and
133 @LAST_MATCH_END English aliases for "@-" and "@+".
134 · File::Find now has pre- and post-processing callbacks. It also
136 correctly changes directories when chasing symbolic links. Call‐
137 backs (naughtily) exiting with "next;" instead of "return;" now
138 work.
139 · File::Glob::glob() renamed to File::Glob::bsd_glob() to avoid pro‐
141 totype mismatch with CORE::glob().
142 · IPC::Open3 now allows the use of numeric file descriptors.
144 · use lib now works identically to @INC. Removing directories with
146 'no lib' now works.
147 · %INC now localised in a Safe compartment so that use/require work.
149 · The Shell module now has an OO interface.
151
153 · The Emacs perl mode (emacs/cperl-mode.el) has been updated to ver‐
154 sion 4.31.
155 · Perlbug is now much more robust. It also sends the bug report to
157 perl.org, not perl.com.
158 · The perlcc utility has been rewritten and its user interface (that
160 is, command line) is much more like that of the UNIX C compiler,
161 cc.
162 · The xsubpp utility for extension writers now understands POD docu‐
164 mentation embedded in the *.xs files.
165
167 · perl56delta details the changes between the 5.005 release and the
168 5.6.0 release.
169 · perldebtut is a Perl debugging tutorial.
171 · perlebcdic contains considerations for running Perl on EBCDIC plat‐
173 forms. Note that unfortunately EBCDIC platforms that used to sup‐
174 ported back in Perl 5.005 are still unsupported by Perl 5.7.0; the
175 plan, however, is to bring them back to the fold.
176 · perlnewmod tells about writing and submitting a new module.
178 · perlposix-bc explains using Perl on the POSIX-BC platform (an
180 EBCDIC mainframe platform).
181 · perlretut is a regular expression tutorial.
183 · perlrequick is a regular expressions quick-start guide. Yes, much
185 quicker than perlretut.
186 · perlutil explains the command line utilities packaged with the Perl
188 distribution.
189
191 · map() that changes the size of the list should now work faster.
192 · sort() has been changed to use mergesort internally as opposed to
194 the earlier quicksort. For very small lists this may result in
195 slightly slower sorting times, but in general the speedup should be
196 at least 20%. Additional bonuses are that the worst case behaviour
197 of sort() is now better (in computer science terms it now runs in
198 time O(N log N), as opposed to quicksort's Theta(N**2) worst-case
199 run time behaviour), and that sort() is now stable (meaning that
200 elements with identical keys will stay ordered as they were before
201 the sort).
202
204 Generic Improvements
205 · INSTALL now explains how you can configure Perl to use 64-bit inte‐
207 gers even on non-64-bit platforms.
208 · Policy.sh policy change: if you are reusing a Policy.sh file (see
210 INSTALL) and you use Configure -Dprefix=/foo/bar and in the old
211 Policy $prefix eq $siteprefix and $prefix eq $vendorprefix, all of
212 them will now be changed to the new prefix, /foo/bar. (Previously
213 only $prefix changed.) If you do not like this new behaviour,
214 specify prefix, siteprefix, and vendorprefix explicitly.
215 · A new optional location for Perl libraries, otherlibdirs, is avail‐
217 able. It can be used for example for vendor add-ons without dis‐
218 turbing Perl's own library directories.
219 · In many platforms the vendor-supplied 'cc' is too stripped-down to
221 build Perl (basically, 'cc' doesn't do ANSI C). If this seems to
222 be the case and 'cc' does not seem to be the GNU C compiler 'gcc',
223 an automatic attempt is made to find and use 'gcc' instead.
224 · gcc needs to closely track the operating system release to avoid
226 build problems. If Configure finds that gcc was built for a differ‐
227 ent operating system release than is running, it now gives a
228 clearly visible warning that there may be trouble ahead.
229 · If binary compatibility with the 5.005 release is not wanted, Con‐
231 figure no longer suggests including the 5.005 modules in @INC.
232 · Configure "-S" can now run non-interactively.
234 · configure.gnu now works with options with whitespace in them.
236 · installperl now outputs everything to STDERR.
238 · $Config{byteorder} is now computed dynamically (this is more robust
240 with "fat binaries" where an executable image contains binaries for
241 more than one binary platform.)
242
244 · Several debugger fixes: exit code now reflects the script exit
245 code, condition "0" now treated correctly, the "d" command now
246 checks line number, the $. no longer gets corrupted, all debugger
247 output now goes correctly to the socket if RemotePort is set.
248 · *foo{FORMAT} now works.
250 · Lexical warnings now propagating correctly between scopes.
252 · Line renumbering with eval and "#line" now works.
254 · Fixed numerous memory leaks, especially in eval "".
256 · Modulus of unsigned numbers now works (4063328477 % 65535 used to
258 return 27406, instead of 27047).
259 · Some "not a number" warnings introduced in 5.6.0 eliminated to be
261 more compatible with 5.005. Infinity is now recognised as a num‐
262 ber.
263 · our() variables will not cause "will not stay shared" warnings.
265 · pack "Z" now correctly terminates the string with "\0".
267 · Fix password routines which in some shadow password platforms (e.g.
269 HP-UX) caused getpwent() to return every other entry.
270 · printf() no longer resets the numeric locale to "C".
272 · "q(a\\b)" now parses correctly as 'a\\b'.
274 · Printing quads (64-bit integers) with printf/sprintf now works
276 without the q L ll prefixes (assuming you are on a quad-capable
277 platform).
278 · Regular expressions on references and overloaded scalars now work.
280 · scalar() now forces scalar context even when used in void context.
282 · sort() arguments are now compiled in the right wantarray context
284 (they were accidentally using the context of the sort() itself).
285 · Changed the POSIX character class "[[:space:]]" to include the
287 (very rare) vertical tab character. Added a new POSIX-ish charac‐
288 ter class "[[:blank:]]" which stands for horizontal whitespace
289 (currently, the space and the tab).
290 · $AUTOLOAD, sort(), lock(), and spawning subprocesses in multiple
292 threads simultaneously are now thread-safe.
293 · Allow read-only string on left hand side of non-modifying tr///.
295 · Several Unicode fixes (but still not perfect).
297 · BOMs (byte order marks) in the beginning of Perl files
299 (scripts, modules) should now be transparently skipped.
300 UTF-16 (UCS-2) encoded Perl files should now be read cor‐
301 rectly.
302 · The character tables have been updated to Unicode 3.0.1.
304 · chr() for values greater than 127 now create utf8 when
306 under use utf8.
307 · Comparing with utf8 data does not magically upgrade
309 non-utf8 data into utf8.
310 · "IsAlnum", "IsAlpha", and "IsWord" now match titlecase.
312 · Concatenation with the "." operator or via variable inter‐
314 polation, "eq", "substr", "reverse", "quotemeta", the "x"
315 operator, substitution with "s///", single-quoted UTF-8,
316 should now work--in theory.
317 · The "tr///" operator now works slightly better but is still
319 rather broken. Note that the "tr///CU" functionality has
320 been removed (but see pack('U0', ...)).
321 · vec() now refuses to deal with characters >255.
323 · Zero entries were missing from the Unicode classes like
325 "IsDigit".
326 · UNIVERSAL::isa no longer caches methods incorrectly. (This broke
328 the Tk extension with 5.6.0.)
329 Platform Specific Changes and Fixes
331 · BSDI 4.*
333 Perl now works on post-4.0 BSD/OSes.
335 · All BSDs
337 Setting $0 now works (as much as possible; see perlvar for
339 details).
340 · Cygwin
342 Numerous updates; currently synchronised with Cygwin 1.1.4.
344 · EPOC
346 EPOC update after Perl 5.6.0. See README.epoc.
348 · FreeBSD 3.*
350 Perl now works on post-3.0 FreeBSDs.
352 · HP-UX
354 README.hpux updated; "Configure -Duse64bitall" now almost works.
356 · IRIX
358 Numerous compilation flag and hint enhancements; accidental mixing
360 of 32-bit and 64-bit libraries (a doomed attempt) made much harder.
361 · Linux
363 Long doubles should now work (see INSTALL).
365 · Mac OS Classic
367 Compilation of the standard Perl distribution in Mac OS Classic
369 should now work if you have the Metrowerks development environment
370 and the missing Mac-specific toolkit bits. Contact the macperl
371 mailing list for details.
372 · MPE/iX
374 MPE/iX update after Perl 5.6.0. See README.mpeix.
376 · NetBSD/sparc
378 Perl now works on NetBSD/sparc.
380 · OS/2
382 Now works with usethreads (see INSTALL).
384 · Solaris
386 64-bitness using the Sun Workshop compiler now works.
388 · Tru64 (aka Digital UNIX, aka DEC OSF/1)
390 The operating system version letter now recorded in $Con‐
392 fig{osvers}. Allow compiling with gcc (previously explicitly for‐
393 bidden). Compiling with gcc still not recommended because buggy
394 code results, even with gcc 2.95.2.
395 · Unicos
397 Fixed various alignment problems that lead into core dumps either
399 during build or later; no longer dies on math errors at runtime;
400 now using full quad integers (64 bits), previously was using only
401 46 bit integers for speed.
402 · VMS
404 chdir() now works better despite a CRT bug; now works with MULTI‐
406 PLICITY (see INSTALL); now works with Perl's malloc.
407 · Windows
409 · accept() no longer leaks memory.
411 · Better chdir() return value for a non-existent directory.
413 · New %ENV entries now propagate to subprocesses.
415 · $ENV{LIB} now used to search for libs under Visual C.
417 · A failed (pseudo)fork now returns undef and sets errno to
419 EAGAIN.
420 · Allow REG_EXPAND_SZ keys in the registry.
422 · Can now send() from all threads, not just the first one.
424 · Fake signal handling reenabled, bugs and all.
426 · Less stack reserved per thread so that more threads can run
428 concurrently. (Still 16M per thread.)
429 · "File::Spec->tmpdir()" now prefers C:/temp over /tmp (works
431 better when perl is running as service).
432 · Better UNC path handling under ithreads.
434 · wait() and waitpid() now work much better.
436 · winsock handle leak fixed.
438
440 All regular expression compilation error messages are now hopefully
441 easier to understand both because the error message now comes before
442 the failed regex and because the point of failure is now clearly
443 marked.
444 The various "opened only for", "on closed", "never opened" warnings
446 drop the "main::" prefix for filehandles in the "main" package, for
447 example "STDIN" instead of <main::STDIN>.
448 The "Unrecognized escape" warning has been extended to include "\8",
450 "\9", and "\_". There is no need to escape any of the "\w" characters.
451
453 · perlapi.pod (a companion to perlguts) now attempts to document the
454 internal API.
455 · You can now build a really minimal perl called microperl. Building
457 microperl does not require even running Configure; "make -f Make‐
458 file.micro" should be enough. Beware: microperl makes many assump‐
459 tions, some of which may be too bold; the resulting executable may
460 crash or otherwise misbehave in wondrous ways. For careful hackers
461 only.
462 · Added rsignal(), whichsig(), do_join() to the publicised API.
464 · Made possible to propagate customised exceptions via croak()ing.
466 · Added is_utf8_char(), is_utf8_string(), bytes_to_utf8(), and
468 utf8_to_bytes().
469 · Now xsubs can have attributes just like subs.
471
473 Unicode Support Still Far From Perfect
474 We're working on it. Stay tuned.
476 EBCDIC Still A Lost Platform
478 The plan is to bring them back.
480 Building Extensions Can Fail Because Of Largefiles
482 Certain extensions like mod_perl and BSD::Resource are known to have
484 issues with `largefiles', a change brought by Perl 5.6.0 in which file
485 offsets default to 64 bits wide, where supported. Modules may fail to
486 compile at all or compile and work incorrectly. Currently there is no
487 good solution for the problem, but Configure now provides appropriate
488 non-largefile ccflags, ldflags, libswanted, and libs in the %Config
489 hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
490 having problems can try configuring themselves without the largefile‐
491 ness. This is admittedly not a clean solution, and the solution may
492 not even work at all. One potential failure is whether one can (or, if
493 one can, whether it's a good idea) link together at all binaries with
494 different ideas about file offsets, all this is platform-dependent.
495 ftmp-security tests warn 'system possibly insecure'
497 Don't panic. Read INSTALL 'make test' section instead.
499 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
501 If perl is configured with -Duse64bitall, the successful result of the
503 subtest 10 of lib/posix may arrive before the successful result of the
504 subtest 9, which confuses the test harness so much that it thinks the
505 subtest 9 failed.
506 Long Doubles Still Don't Work In Solaris
508 The experimental long double support is still very much so in Solaris.
510 (Other platforms like Linux and Tru64 are beginning to solidify in this
511 area.)
512 Linux With Sfio Fails op/misc Test 48
514 No known fix.
516 Storable tests fail in some platforms
518 If any Storable tests fail the use of Storable is not advisable.
520 · Many Storable tests fail on AIX configured with 64 bit integers.
522 So far unidentified problems break Storable in AIX if Perl is con‐
524 figured to use 64 bit integers. AIX in 32-bit mode works and other
525 64-bit platforms work with Storable.
526 · DOS DJGPP may hang when testing Storable.
528 · st-06compat fails in UNICOS and UNICOS/mk.
530 This means that you cannot read old (pre-Storable-0.7) Storable
532 images made in other platforms.
533 · st-store.t and st-retrieve may fail with Compaq C 6.2 on OpenVMS
535 Alpha 7.2.
536 Threads Are Still Experimental
538 Multithreading is still an experimental feature. Some platforms emit
540 the following message for lib/thr5005
541 #
543 # This is a KNOWN FAILURE, and one of the reasons why threading
544 # is still an experimental feature. It is here to stop people
545 # from deploying threads in production. ;-)
546 #
547 and another known thread-related warning is
549 pragma/overload......Unbalanced saves: 3 more saves than restores
551 panic: magic_mutexfree during global destruction.
552 ok
553 lib/selfloader.......Unbalanced saves: 3 more saves than restores
554 panic: magic_mutexfree during global destruction.
555 ok
556 lib/st-dclone........Unbalanced saves: 3 more saves than restores
557 panic: magic_mutexfree during global destruction.
558 ok
559 The Compiler Suite Is Still Experimental
561 The compiler suite is slowly getting better but is nowhere near working
563 order yet. The backend part that has seen perhaps the most progress is
564 the bytecode compiler.
565
567 If you find what you think is a bug, you might check the articles
568 recently posted to the comp.lang.perl.misc newsgroup and the perl bug
569 database at http://bugs.perl.org/ There may also be information at
570 http://www.perl.com/perl/ , the Perl Home Page.
571 If you believe you have an unreported bug, please run the perlbug pro‐
573 gram included with your release. Be sure to trim your bug down to a
574 tiny but sufficient test case. Your bug report, along with the output
575 of "perl -V", will be sent off to perlbug@perl.org to be analysed by
576 the Perl porting team.
577
579 The Changes file for exhaustive details on what changed.
580 The INSTALL file for how to build Perl.
582 The README file for general stuff.
584 The Artistic and Copying files for copyright information.
586
588 Written by Jarkko Hietaniemi <jhi@iki.fi>, with many contributions from
589 The Perl Porters and Perl Users submitting feedback and patches.
590 Send omissions or corrections to <perlbug@perl.org>.
592perl v5.8.8 2006-01-07 PERL570DELTA(1)