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   1  =head1 NAME
   2  
   3  perl571delta - what's new for perl v5.7.1
   4  
   5  =head1 DESCRIPTION
   6  
   7  This document describes differences between the 5.7.0 release and the
   8  5.7.1 release.  
   9  
  10  (To view the differences between the 5.6.0 release and the 5.7.0
  11  release, see L<perl570delta>.)
  12  
  13  =head1 Security Vulnerability Closed
  14  
  15  (This change was already made in 5.7.0 but bears repeating here.)
  16  
  17  A potential security vulnerability in the optional suidperl component
  18  of Perl was identified in August 2000.  suidperl is neither built nor
  19  installed by default.  As of April 2001 the only known vulnerable
  20  platform is Linux, most likely all Linux distributions.  CERT and
  21  various vendors and distributors have been alerted about the vulnerability.
  22  See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
  23  for more information.
  24  
  25  The problem was caused by Perl trying to report a suspected security
  26  exploit attempt using an external program, /bin/mail.  On Linux
  27  platforms the /bin/mail program had an undocumented feature which
  28  when combined with suidperl gave access to a root shell, resulting in
  29  a serious compromise instead of reporting the exploit attempt.  If you
  30  don't have /bin/mail, or if you have 'safe setuid scripts', or if
  31  suidperl is not installed, you are safe.
  32  
  33  The exploit attempt reporting feature has been completely removed from
  34  all the Perl 5.7 releases (and will be gone also from the maintenance
  35  release 5.6.1), so that particular vulnerability isn't there anymore.
  36  However, further security vulnerabilities are, unfortunately, always
  37  possible.  The suidperl code is being reviewed and if deemed too risky
  38  to continue to be supported, it may be completely removed from future
  39  releases.  In any case, suidperl should only be used by security
  40  experts who know exactly what they are doing and why they are using
  41  suidperl instead of some other solution such as sudo
  42  ( see http://www.courtesan.com/sudo/ ).
  43  
  44  =head1 Incompatible Changes
  45  
  46  =over 4
  47  
  48  =item *
  49  
  50  Although "you shouldn't do that", it was possible to write code that
  51  depends on Perl's hashed key order (Data::Dumper does this).  The new
  52  algorithm "One-at-a-Time" produces a different hashed key order.
  53  More details are in L</"Performance Enhancements">.
  54  
  55  =item *
  56  
  57  The list of filenames from glob() (or <...>) is now by default sorted
  58  alphabetically to be csh-compliant.  (bsd_glob() does still sort platform
  59  natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
  60  
  61  =back
  62  
  63  =head1 Core Enhancements
  64  
  65  =head2 AUTOLOAD Is Now Lvaluable
  66  
  67  AUTOLOAD is now lvaluable, meaning that you can add the :lvalue attribute
  68  to AUTOLOAD subroutines and you can assign to the AUTOLOAD return value.
  69  
  70  =head2 PerlIO is Now The Default
  71  
  72  =over 4
  73  
  74  =item *
  75  
  76  IO is now by default done via PerlIO rather than system's "stdio".
  77  PerlIO allows "layers" to be "pushed" onto a file handle to alter the
  78  handle's behaviour.  Layers can be specified at open time via 3-arg
  79  form of open:
  80  
  81     open($fh,'>:crlf :utf8', $path) || ...
  82  
  83  or on already opened handles via extended C<binmode>:
  84  
  85     binmode($fh,':encoding(iso-8859-7)');
  86  
  87  The built-in layers are: unix (low level read/write), stdio (as in
  88  previous Perls), perlio (re-implementation of stdio buffering in a
  89  portable manner), crlf (does CRLF <=> "\n" translation as on Win32,
  90  but available on any platform).  A mmap layer may be available if
  91  platform supports it (mostly UNIXes).
  92  
  93  Layers to be applied by default may be specified via the 'open' pragma.
  94  
  95  See L</"Installation and Configuration Improvements"> for the effects
  96  of PerlIO on your architecture name.
  97  
  98  =item *
  99  
 100  File handles can be marked as accepting Perl's internal encoding of Unicode
 101  (UTF-8 or UTF-EBCDIC depending on platform) by a pseudo layer ":utf8" :
 102  
 103     open($fh,">:utf8","Uni.txt");
 104  
 105  Note for EBCDIC users: the pseudo layer ":utf8" is erroneously named
 106  for you since it's not UTF-8 what you will be getting but instead
 107  UTF-EBCDIC.  See L<perlunicode>, L<utf8>, and
 108  http://www.unicode.org/unicode/reports/tr16/ for more information.
 109  In future releases this naming may change.
 110  
 111  =item *
 112  
 113  File handles can translate character encodings from/to Perl's internal
 114  Unicode form on read/write via the ":encoding()" layer.
 115  
 116  =item *
 117  
 118  File handles can be opened to "in memory" files held in Perl scalars via:
 119  
 120     open($fh,'>', \$variable) || ...
 121  
 122  =item *
 123  
 124  Anonymous temporary files are available without need to
 125  'use FileHandle' or other module via
 126  
 127     open($fh,"+>", undef) || ...
 128  
 129  That is a literal undef, not an undefined value.
 130  
 131  =item *
 132  
 133  The list form of C<open> is now implemented for pipes (at least on UNIX):
 134  
 135     open($fh,"-|", 'cat', '/etc/motd')
 136  
 137  creates a pipe, and runs the equivalent of exec('cat', '/etc/motd') in
 138  the child process.
 139  
 140  =item *
 141  
 142  The following builtin functions are now overridable: chop(), chomp(),
 143  each(), keys(), pop(), push(), shift(), splice(), unshift().
 144  
 145  =item *
 146  
 147  Formats now support zero-padded decimal fields.
 148  
 149  =item *
 150  
 151  Perl now tries internally to use integer values in numeric conversions
 152  and basic arithmetics (+ - * /) if the arguments are integers, and
 153  tries also to keep the results stored internally as integers.
 154  This change leads into often slightly faster and always less lossy
 155  arithmetics. (Previously Perl always preferred floating point numbers
 156  in its math.)
 157  
 158  =item *
 159  
 160  The printf() and sprintf() now support parameter reordering using the
 161  C<%\d+\$> and C<*\d+\$> syntaxes.  For example
 162  
 163      print "%2\$s %1\$s\n", "foo", "bar";
 164  
 165  will print "bar foo\n"; This feature helps in writing
 166  internationalised software.
 167  
 168  =item *
 169  
 170  Unicode in general should be now much more usable.  Unicode can be
 171  used in hash keys, Unicode in regular expressions should work now,
 172  Unicode in tr/// should work now (though tr/// seems to be a
 173  particularly tricky to get right, so you have been warned)
 174  
 175  =item *
 176  
 177  The Unicode Character Database coming with Perl has been upgraded
 178  to Unicode 3.1.  For more information, see http://www.unicode.org/ ,
 179  and http://www.unicode.org/unicode/reports/tr27/
 180  
 181  For developers interested in enhancing Perl's Unicode capabilities:
 182  almost all the UCD files are included with the Perl distribution in
 183  the lib/unicode subdirectory.  The most notable omission, for space
 184  considerations, is the Unihan database.
 185  
 186  =item *
 187  
 188  The Unicode character classes \p{Blank} and \p{SpacePerl} have been
 189  added.  "Blank" is like C isblank(), that is, it contains only
 190  "horizontal whitespace" (the space character is, the newline isn't),
 191  and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
 192  isn't, since that includes the vertical tabulator character, whereas
 193  C<\s> doesn't.)
 194  
 195  =back
 196  
 197  =head2 Signals Are Now Safe
 198  
 199  Perl used to be fragile in that signals arriving at inopportune moments
 200  could corrupt Perl's internal state.
 201  
 202  =head1 Modules and Pragmata
 203  
 204  =head2 New Modules
 205  
 206  =over 4
 207  
 208  =item *
 209  
 210  B::Concise, by Stephen McCamant, is a new compiler backend for
 211  walking the Perl syntax tree, printing concise info about ops.
 212  The output is highly customisable.
 213  
 214  See L<B::Concise> for more information.
 215  
 216  =item *
 217  
 218  Class::ISA, by Sean Burke, for reporting the search path for a
 219  class's ISA tree, has been added.
 220  
 221  See L<Class::ISA> for more information.
 222  
 223  =item *
 224  
 225  Cwd has now a split personality: if possible, an extension is used,
 226  (this will hopefully be both faster and more secure and robust) but
 227  if not possible, the familiar Perl library implementation is used.
 228  
 229  =item *
 230  
 231  Digest, a frontend module for calculating digests (checksums),
 232  from Gisle Aas, has been added.
 233  
 234  See L<Digest> for more information.
 235  
 236  =item *
 237  
 238  Digest::MD5 for calculating MD5 digests (checksums), by Gisle Aas,
 239  has been added.
 240  
 241      use Digest::MD5 'md5_hex';
 242  
 243      $digest = md5_hex("Thirsty Camel");
 244  
 245      print $digest, "\n"; # 01d19d9d2045e005c3f1b80e8b164de1
 246  
 247  NOTE: the MD5 backward compatibility module is deliberately not
 248  included since its use is discouraged.
 249  
 250  See L<Digest::MD5> for more information.
 251  
 252  =item *
 253  
 254  Encode, by Nick Ing-Simmons, provides a mechanism to translate
 255  between different character encodings.  Support for Unicode,
 256  ISO-8859-*, ASCII, CP*, KOI8-R, and three variants of EBCDIC are
 257  compiled in to the module.  Several other encodings (like Japanese,
 258  Chinese, and MacIntosh encodings) are included and will be loaded at
 259  runtime.
 260  
 261  Any encoding supported by Encode module is also available to the
 262  ":encoding()" layer if PerlIO is used.
 263  
 264  See L<Encode> for more information.
 265  
 266  =item *
 267  
 268  Filter::Simple is an easy-to-use frontend to Filter::Util::Call,
 269  from Damian Conway.
 270  
 271      # in MyFilter.pm:
 272  
 273      package MyFilter;
 274  
 275      use Filter::Simple sub {
 276          while (my ($from, $to) = splice @_, 0, 2) {
 277                  s/$from/$to/g;
 278          }
 279      };
 280  
 281      1;
 282  
 283      # in user's code:
 284  
 285      use MyFilter qr/red/ => 'green';
 286  
 287      print "red\n";   # this code is filtered, will print "green\n"
 288      print "bored\n"; # this code is filtered, will print "bogreen\n"
 289  
 290      no MyFilter;
 291  
 292      print "red\n";   # this code is not filtered, will print "red\n"
 293  
 294  See L<Filter::Simple> for more information.
 295  
 296  =item *
 297  
 298  Filter::Util::Call, by Paul Marquess, provides you with the
 299  framework to write I<Source Filters> in Perl.  For most uses
 300  the frontend Filter::Simple is to be preferred.
 301  See L<Filter::Util::Call> for more information.
 302  
 303  =item *
 304  
 305  Locale::Constants, Locale::Country, Locale::Currency, and Locale::Language,
 306  from Neil Bowers, have been added.  They provide the codes for various
 307  locale standards, such as "fr" for France, "usd" for US Dollar, and
 308  "jp" for Japanese.
 309  
 310      use Locale::Country;
 311  
 312      $country = code2country('jp');               # $country gets 'Japan'
 313      $code    = country2code('Norway');           # $code gets 'no'
 314  
 315  See L<Locale::Constants>, L<Locale::Country>, L<Locale::Currency>,
 316  and L<Locale::Language> for more information.
 317  
 318  =item *
 319  
 320  MIME::Base64, by Gisle Aas, allows you to encode data in base64.
 321  
 322      use MIME::Base64;
 323  
 324      $encoded = encode_base64('Aladdin:open sesame');
 325      $decoded = decode_base64($encoded);
 326  
 327      print $encoded, "\n"; # "QWxhZGRpbjpvcGVuIHNlc2FtZQ=="
 328  
 329  See L<MIME::Base64> for more information.
 330  
 331  =item *
 332  
 333  MIME::QuotedPrint, by Gisle Aas, allows you to encode data in
 334  quoted-printable encoding.
 335  
 336      use MIME::QuotedPrint;
 337  
 338      $encoded = encode_qp("Smiley in Unicode: \x{263a}");
 339      $decoded = decode_qp($encoded);
 340  
 341      print $encoded, "\n"; # "Smiley in Unicode: =263A"
 342  
 343  MIME::QuotedPrint has been enhanced to provide the basic methods
 344  necessary to use it with PerlIO::Via as in :
 345  
 346      use MIME::QuotedPrint;
 347      open($fh,">Via(MIME::QuotedPrint)",$path)
 348  
 349  See L<MIME::QuotedPrint> for more information.
 350  
 351  =item *
 352  
 353  PerlIO::Scalar, by Nick Ing-Simmons, provides the implementation of
 354  IO to "in memory" Perl scalars as discussed above.  It also serves as
 355  an example of a loadable layer.  Other future possibilities include
 356  PerlIO::Array and PerlIO::Code.  See L<PerlIO::Scalar> for more
 357  information.
 358  
 359  =item *
 360  
 361  PerlIO::Via, by Nick Ing-Simmons, acts as a PerlIO layer and wraps
 362  PerlIO layer functionality provided by a class (typically implemented
 363  in perl code).
 364  
 365      use MIME::QuotedPrint;
 366      open($fh,">Via(MIME::QuotedPrint)",$path)
 367  
 368  This will automatically convert everything output to C<$fh>
 369  to Quoted-Printable.  See L<PerlIO::Via> for more information.
 370  
 371  =item *
 372  
 373  Pod::Text::Overstrike, by Joe Smith, has been added.
 374  It converts POD data to formatted overstrike text.
 375  See L<Pod::Text::Overstrike> for more information.
 376  
 377  =item *
 378  
 379  Switch from Damian Conway has been added.  Just by saying
 380  
 381      use Switch;
 382  
 383  you have C<switch> and C<case> available in Perl.
 384  
 385      use Switch;
 386  
 387      switch ($val) {
 388  
 389          case 1        { print "number 1" }
 390          case "a"    { print "string a" }
 391          case [1..10,42]    { print "number in list" }
 392          case (@array)    { print "number in list" }
 393          case /\w+/    { print "pattern" }
 394          case qr/\w+/    { print "pattern" }
 395          case (%hash)    { print "entry in hash" }
 396          case (\%hash)    { print "entry in hash" }
 397          case (\&sub)    { print "arg to subroutine" }
 398          else        { print "previous case not true" }
 399      }
 400  
 401  See L<Switch> for more information.
 402  
 403  =item *
 404  
 405  Text::Balanced from Damian Conway has been added, for
 406  extracting delimited text sequences from strings.
 407  
 408      use Text::Balanced 'extract_delimited';
 409  
 410      ($a, $b) = extract_delimited("'never say never', he never said", "'", '');
 411  
 412  $a will be "'never say never'", $b will be ', he never said'.
 413  
 414  In addition to extract_delimited() there are also extract_bracketed(),
 415  extract_quotelike(), extract_codeblock(), extract_variable(),
 416  extract_tagged(), extract_multiple(), gen_delimited_pat(), and
 417  gen_extract_tagged().  With these you can implement rather advanced
 418  parsing algorithms.  See L<Text::Balanced> for more information.
 419  
 420  =item *
 421  
 422  Tie::RefHash::Nestable, by Edward Avis, allows storing hash references
 423  (unlike the standard Tie::RefHash)  The module is contained within
 424  Tie::RefHash.
 425  
 426  =item *
 427  
 428  XS::Typemap, by Tim Jenness, is a test extension that exercises XS
 429  typemaps.  Nothing gets installed but for extension writers the code
 430  is worth studying.
 431  
 432  =back
 433  
 434  =head2 Updated And Improved Modules and Pragmata
 435  
 436  =over 4
 437  
 438  =item *
 439  
 440  B::Deparse should be now more robust.  It still far from providing a full
 441  round trip for any random piece of Perl code, though, and is under active
 442  development: expect more robustness in 5.7.2.
 443  
 444  =item *
 445  
 446  Class::Struct can now define the classes in compile time.
 447  
 448  =item *
 449  
 450  Math::BigFloat has undergone much fixing, and in addition the fmod()
 451  function now supports modulus operations.
 452  
 453  ( The fixed Math::BigFloat module is also available in CPAN for those
 454  who can't upgrade their Perl: http://www.cpan.org/authors/id/J/JP/JPEACOCK/ )
 455  
 456  =item *
 457  
 458  Devel::Peek now has an interface for the Perl memory statistics
 459  (this works only if you are using perl's malloc, and if you have
 460  compiled with debugging).
 461  
 462  =item *
 463  
 464  IO::Socket has now atmark() method, which returns true if the socket
 465  is positioned at the out-of-band mark.  The method is also exportable
 466  as a sockatmark() function.
 467  
 468  =item *
 469  
 470  IO::Socket::INET has support for ReusePort option (if your platform
 471  supports it).  The Reuse option now has an alias, ReuseAddr.  For clarity
 472  you may want to prefer ReuseAddr.
 473  
 474  =item *
 475  
 476  Net::Ping has been enhanced.  There is now "external" protocol which
 477  uses Net::Ping::External module which runs external ping(1) and parses
 478  the output.  An alpha version of Net::Ping::External is available in
 479  CPAN and in 5.7.2 the Net::Ping::External may be integrated to Perl.
 480  
 481  =item *
 482  
 483  The C<open> pragma allows layers other than ":raw" and ":crlf" when
 484  using PerlIO.
 485  
 486  =item *
 487  
 488  POSIX::sigaction() is now much more flexible and robust.
 489  You can now install coderef handlers, 'DEFAULT', and 'IGNORE'
 490  handlers, installing new handlers was not atomic.
 491  
 492  =item *
 493  
 494  The Test module has been significantly enhanced.  Its use is
 495  greatly recommended for module writers.
 496  
 497  =item *
 498  
 499  The utf8:: name space (as in the pragma) provides various
 500  Perl-callable functions to provide low level access to Perl's
 501  internal Unicode representation.  At the moment only length()
 502  has been implemented.
 503  
 504  =back
 505  
 506  The following modules have been upgraded from the versions at CPAN:
 507  CPAN, CGI, DB_File, File::Temp, Getopt::Long, Pod::Man, Pod::Text,
 508  Storable, Text-Tabs+Wrap.
 509  
 510  =head1 Performance Enhancements
 511  
 512  =over 4
 513  
 514  =item *
 515  
 516  Hashes now use Bob Jenkins "One-at-a-Time" hashing key algorithm
 517  ( http://burtleburtle.net/bob/hash/doobs.html ).  This algorithm is
 518  reasonably fast while producing a much better spread of values than
 519  the old hashing algorithm (originally by Chris Torek, later tweaked by
 520  Ilya Zakharevich).  Hash values output from the algorithm on a hash of
 521  all 3-char printable ASCII keys comes much closer to passing the
 522  DIEHARD random number generation tests.  According to perlbench, this
 523  change has not affected the overall speed of Perl.
 524  
 525  =item *
 526  
 527  unshift() should now be noticeably faster.
 528  
 529  =back
 530  
 531  =head1 Utility Changes
 532  
 533  =over 4
 534  
 535  =item *
 536  
 537  h2xs now produces template README.
 538  
 539  =item *
 540  
 541  s2p has been completely rewritten in Perl.  (It is in fact a full
 542  implementation of sed in Perl.)
 543  
 544  =item *
 545  
 546  xsubpp now supports OUT keyword.
 547  
 548  =back
 549  
 550  =head1 New Documentation
 551  
 552  =head2 perlclib
 553  
 554  Internal replacements for standard C library functions.
 555  (Interesting only for extension writers and Perl core hackers.)
 556  
 557  =head2 perliol
 558  
 559  Internals of PerlIO with layers.
 560  
 561  =head2 README.aix
 562  
 563  Documentation on compiling Perl on AIX has been added.  AIX has
 564  several different C compilers and getting the right patch level
 565  is essential.  On install README.aix will be installed as L<perlaix>.
 566  
 567  =head2 README.bs2000
 568  
 569  Documentation on compiling Perl on the POSIX-BC platform (an EBCDIC
 570  mainframe environment) has been added.
 571  
 572  This was formerly known as README.posix-bc but the name was considered
 573  to be too confusing (it has nothing to do with the POSIX module or the
 574  POSIX standard).  On install README.bs2000 will be installed as L<perlbs2000>.
 575  
 576  =head2 README.macos
 577  
 578  In perl 5.7.1 (and in the 5.6.1) the MacPerl sources have been
 579  synchronised with the standard Perl sources.  To compile MacPerl
 580  some additional steps are required, and this file documents those
 581  steps.  On install README.macos will be installed as L<perlmacos>.
 582  
 583  =head2 README.mpeix
 584  
 585  The README.mpeix has been podified, which means that this information
 586  about compiling and using Perl on the MPE/iX miniframe platform will
 587  be installed as L<perlmpeix>.
 588  
 589  =head2 README.solaris
 590  
 591  README.solaris has been created and Solaris wisdom from elsewhere
 592  in the Perl documentation has been collected there.  On install
 593  README.solaris will be installed as L<perlsolaris>.
 594  
 595  =head2 README.vos
 596  
 597  The README.vos has been podified, which means that this information
 598  about compiling and using Perl on the Stratus VOS miniframe platform
 599  will be installed as L<perlvos>.
 600  
 601  =head2 Porting/repository.pod
 602  
 603  Documentation on how to use the Perl source repository has been added.
 604  
 605  =head1 Installation and Configuration Improvements
 606  
 607  =over 4
 608  
 609  =item *
 610  
 611  Because PerlIO is now the default on most platforms, "-perlio" doesn't
 612  get appended to the $Config{archname} (also known as $^O) anymore.
 613  Instead, if you explicitly choose not to use perlio (Configure command
 614  line option -Uuseperlio), you will get "-stdio" appended.
 615  
 616  =item *
 617  
 618  Another change related to the architecture name is that "-64all"
 619  (-Duse64bitall, or "maximally 64-bit") is appended only if your
 620  pointers are 64 bits wide.  (To be exact, the use64bitall is ignored.)
 621  
 622  =item *
 623  
 624  APPLLIB_EXP, a less-know configuration-time definition, has been
 625  documented.  It can be used to prepend site-specific directories
 626  to Perl's default search path (@INC), see INSTALL for information.
 627  
 628  =item *
 629  
 630  Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
 631  has been documented in INSTALL.
 632  
 633  =item *
 634  
 635  If you are on IRIX or Tru64 platforms, new profiling/debugging options
 636  have been added, see L<perlhack> for more information about pixie and
 637  Third Degree.
 638  
 639  =back
 640  
 641  =head2 New Or Improved Platforms
 642  
 643  For the list of platforms known to support Perl,
 644  see L<perlport/"Supported Platforms">.
 645  
 646  =over 4
 647  
 648  =item *
 649  
 650  AIX dynamic loading should be now better supported.
 651  
 652  =item *
 653  
 654  After a long pause, AmigaOS has been verified to be happy with Perl.
 655  
 656  =item *
 657  
 658  EBCDIC platforms (z/OS, also known as OS/390, POSIX-BC, and VM/ESA)
 659  have been regained.  Many test suite tests still fail and the
 660  co-existence of Unicode and EBCDIC isn't quite settled, but the
 661  situation is much better than with Perl 5.6.  See L<perlos390>,
 662  L<perlbs2000> (for POSIX-BC), and L<perlvmesa> for more information.
 663  
 664  =item *
 665  
 666  Building perl with -Duseithreads or -Duse5005threads now works under
 667  HP-UX 10.20 (previously it only worked under 10.30 or later). You will
 668  need a thread library package installed. See README.hpux.
 669  
 670  =item *
 671  
 672  Mac OS Classic (MacPerl has of course been available since
 673  perl 5.004 but now the source code bases of standard Perl
 674  and MacPerl have been synchronised)
 675  
 676  =item *
 677  
 678  NCR MP-RAS is now supported.
 679  
 680  =item *
 681  
 682  NonStop-UX is now supported.
 683  
 684  =item *
 685  
 686  Amdahl UTS is now supported.
 687  
 688  =item *
 689  
 690  z/OS (formerly known as OS/390, formerly known as MVS OE) has now
 691  support for dynamic loading.  This is not selected by default,
 692  however, you must specify -Dusedl in the arguments of Configure.
 693  
 694  =back
 695  
 696  =head2 Generic Improvements
 697  
 698  =over 4
 699  
 700  =item *
 701  
 702  Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
 703  when building the Perl binary.  The only exception to this is SunOS 4.x,
 704  which needs them.
 705  
 706  =item *
 707  
 708  Some new Configure symbols, useful for extension writers:
 709  
 710  =over 8
 711  
 712  =item d_cmsghdr
 713  
 714  For struct cmsghdr.
 715  
 716  =item d_fcntl_can_lock
 717  
 718  Whether fcntl() can be used for file locking.
 719  
 720  =item d_fsync
 721  
 722  =item d_getitimer
 723  
 724  =item d_getpagsz
 725  
 726  For getpagesize(), though you should prefer POSIX::sysconf(_SC_PAGE_SIZE))
 727  
 728  =item d_msghdr_s
 729  
 730  For struct msghdr.
 731  
 732  =item need_va_copy
 733  
 734  Whether one needs to use Perl_va_copy() to copy varargs.
 735  
 736  =item d_readv
 737  
 738  =item d_recvmsg
 739  
 740  =item d_sendmsg
 741  
 742  =item sig_size
 743  
 744  The number of elements in an array needed to hold all the available signals.
 745  
 746  =item d_sockatmark
 747  
 748  =item d_strtoq
 749  
 750  =item d_u32align
 751  
 752  Whether one needs to access character data aligned by U32 sized pointers.
 753  
 754  =item d_ualarm
 755  
 756  =item d_usleep
 757  
 758  =back
 759  
 760  =item *
 761  
 762  Removed Configure symbols: the PDP-11 memory model settings: huge,
 763  large, medium, models.
 764  
 765  =item *
 766  
 767  SOCKS support is now much more robust.
 768  
 769  =item *
 770  
 771  If your file system supports symbolic links you can build Perl outside
 772  of the source directory by
 773  
 774      mkdir perl/build/directory
 775      cd perl/build/directory
 776      sh /path/to/perl/source/Configure -Dmksymlinks ...
 777  
 778  This will create in perl/build/directory a tree of symbolic links
 779  pointing to files in /path/to/perl/source.  The original files are left
 780  unaffected.  After Configure has finished you can just say
 781  
 782      make all test
 783  
 784  and Perl will be built and tested, all in perl/build/directory.
 785  
 786  =back
 787  
 788  =head1 Selected Bug Fixes
 789  
 790  Numerous memory leaks and uninitialized memory accesses have been hunted down.
 791  Most importantly anonymous subs used to leak quite a bit.
 792  
 793  =over 4
 794  
 795  =item *
 796  
 797  chop(@list) in list context returned the characters chopped in
 798  reverse order.  This has been reversed to be in the right order.
 799  
 800  =item *
 801  
 802  The order of DESTROYs has been made more predictable.
 803  
 804  =item *
 805  
 806  mkdir() now ignores trailing slashes in the directory name,
 807  as mandated by POSIX.
 808  
 809  =item *
 810  
 811  Attributes (like :shared) didn't work with our().
 812  
 813  =item *
 814  
 815  The PERL5OPT environment variable (for passing command line arguments
 816  to Perl) didn't work for more than a single group of options.
 817  
 818  =item *
 819  
 820  The tainting behaviour of sprintf() has been rationalized.  It does
 821  not taint the result of floating point formats anymore, making the
 822  behaviour consistent with that of string interpolation.
 823  
 824  =item *
 825  
 826  All but the first argument of the IO syswrite() method are now optional.
 827  
 828  =item *
 829  
 830  Tie::ARRAY SPLICE method was broken.
 831  
 832  =item *
 833  
 834  vec() now tries to work with characters <= 255 when possible, but it leaves
 835  higher character values in place.  In that case, if vec() was used to modify
 836  the string, it is no longer considered to be utf8-encoded.
 837  
 838  =back
 839  
 840  =head2 Platform Specific Changes and Fixes
 841  
 842  =over 4
 843  
 844  =item *
 845  
 846  Linux previously had problems related to sockaddrlen when using
 847  accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
 848  
 849  =item *
 850  
 851  Previously DYNIX/ptx had problems in its Configure probe for non-blocking I/O.
 852  
 853  =item *
 854  
 855  Windows
 856  
 857  =over 8
 858  
 859  =item *
 860  
 861  Borland C++ v5.5 is now a supported compiler that can build Perl.
 862  However, the generated binaries continue to be incompatible with those
 863  generated by the other supported compilers (GCC and Visual C++).
 864  
 865  =item *
 866  
 867  Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root.
 868  Other bugs in chdir() and Cwd::cwd() have also been fixed.
 869  
 870  =item *
 871  
 872  Duping socket handles with open(F, ">&MYSOCK") now works under Windows 9x.
 873  
 874  =item *
 875  
 876  HTML files will be installed in c:\perl\html instead of c:\perl\lib\pod\html
 877  
 878  =item *
 879  
 880  The makefiles now provide a single switch to bulk-enable all the features
 881  enabled in ActiveState ActivePerl (a popular binary distribution).
 882  
 883  =back
 884  
 885  =back
 886  
 887  =head1 New or Changed Diagnostics
 888  
 889  Two new debugging options have been added: if you have compiled your
 890  Perl with debugging, you can use the -DT and -DR options to trace
 891  tokenising and to add reference counts to displaying variables,
 892  respectively.
 893  
 894  =over 4
 895  
 896  =item *
 897  
 898  If an attempt to use a (non-blessed) reference as an array index
 899  is made, a warning is given.
 900  
 901  =item *
 902  
 903  C<push @a;> and C<unshift @a;> (with no values to push or unshift)
 904  now give a warning.  This may be a problem for generated and eval'ed
 905  code.
 906  
 907  =back
 908  
 909  =head1 Changed Internals
 910  
 911  =over 4
 912  
 913  =item *
 914  
 915  Some new APIs: ptr_table_clear(), ptr_table_free(), sv_setref_uv().
 916  For the full list of the available APIs see L<perlapi>.
 917  
 918  =item *
 919  
 920  dTHR and djSP have been obsoleted; the former removed (because it's
 921  a no-op) and the latter replaced with dSP.
 922  
 923  =item *
 924  
 925  Perl now uses system malloc instead of Perl malloc on all 64-bit
 926  platforms, and even in some not-always-64-bit platforms like AIX,
 927  IRIX, and Solaris.  This change breaks backward compatibility but
 928  Perl's malloc has problems with large address spaces and also the
 929  speed of vendors' malloc is generally better in large address space
 930  machines (Perl's malloc is mostly tuned for space).
 931  
 932  =back
 933  
 934  =head1 New Tests
 935  
 936  Many new tests have been added.  The most notable is probably the
 937  lib/1_compile: it is very notable because running it takes quite a
 938  long time -- it test compiles all the Perl modules in the distribution.
 939  Please be patient.
 940  
 941  =head1 Known Problems
 942  
 943  Note that unlike other sections in this document (which describe
 944  changes since 5.7.0) this section is cumulative containing known
 945  problems for all the 5.7 releases.
 946  
 947  =head2 AIX vac 5.0.0.0 May Produce Buggy Code For Perl
 948  
 949  The AIX C compiler vac version 5.0.0.0 may produce buggy code,
 950  resulting in few random tests failing, but when the failing tests
 951  are run by hand, they succeed.  We suggest upgrading to at least
 952  vac version 5.0.1.0, that has been known to compile Perl correctly.
 953  "lslpp -L|grep vac.C" will tell you the vac version.
 954  
 955  =head2 lib/ftmp-security tests warn 'system possibly insecure'
 956  
 957  Don't panic.  Read INSTALL 'make test' section instead.
 958  
 959  =head2 lib/io_multihomed Fails In LP64-Configured HP-UX
 960  
 961  The lib/io_multihomed test may hang in HP-UX if Perl has been
 962  configured to be 64-bit. Because other 64-bit platforms do not hang in
 963  this test, HP-UX is suspect. All other tests pass in 64-bit HP-UX. The
 964  test attempts to create and connect to "multihomed" sockets (sockets
 965  which have multiple IP addresses).
 966  
 967  =head2 Test lib/posix Subtest 9 Fails In LP64-Configured HP-UX
 968  
 969  If perl is configured with -Duse64bitall, the successful result of the
 970  subtest 10 of lib/posix may arrive before the successful result of the
 971  subtest 9, which confuses the test harness so much that it thinks the
 972  subtest 9 failed.
 973  
 974  =head2 lib/b test 19
 975  
 976  The test fails on various platforms (PA64 and IA64 are known), but the
 977  exact cause is still being investigated.
 978  
 979  =head2 Linux With Sfio Fails op/misc Test 48
 980  
 981  No known fix.
 982  
 983  =head2 sigaction test 13 in VMS
 984  
 985  The test is known to fail; whether it's because of VMS of because
 986  of faulty test is not known.
 987  
 988  =head2 sprintf tests 129 and 130
 989  
 990  The op/sprintf tests 129 and 130 are known to fail on some platforms.
 991  Examples include any platform using sfio, and Compaq/Tandem's NonStop-UX.
 992  The failing platforms do not comply with the ANSI C Standard, line
 993  19ff on page 134 of ANSI X3.159 1989 to be exact.  (They produce
 994  something else than "1" and "-1" when formatting 0.6 and -0.6 using
 995  the printf format "%.0f", most often they produce "0" and "-0".)
 996  
 997  =head2  Failure of Thread tests
 998  
 999  The subtests 19 and 20 of lib/thr5005.t test are known to fail due to
1000  fundamental problems in the 5.005 threading implementation. These are
1001  not new failures--Perl 5.005_0x has the same bugs, but didn't have
1002  these tests. (Note that support for 5.005-style threading remains
1003  experimental.)
1004  
1005  =head2 Localising a Tied Variable Leaks Memory
1006  
1007      use Tie::Hash;
1008      tie my %tie_hash => 'Tie::StdHash';
1009  
1010      ...
1011  
1012      local($tie_hash{Foo}) = 1; # leaks
1013  
1014  Code like the above is known to leak memory every time the local()
1015  is executed.
1016  
1017  =head2 Self-tying of Arrays and Hashes Is Forbidden
1018  
1019  Self-tying of arrays and hashes is broken in rather deep and
1020  hard-to-fix ways.  As a stop-gap measure to avoid people from getting
1021  frustrated at the mysterious results (core dumps, most often) it is
1022  for now forbidden (you will get a fatal error even from an attempt).
1023  
1024  =head2 Building Extensions Can Fail Because Of Largefiles
1025  
1026  Some extensions like mod_perl are known to have issues with
1027  `largefiles', a change brought by Perl 5.6.0 in which file offsets
1028  default to 64 bits wide, where supported.  Modules may fail to compile
1029  at all or compile and work incorrectly.  Currently there is no good
1030  solution for the problem, but Configure now provides appropriate
1031  non-largefile ccflags, ldflags, libswanted, and libs in the %Config
1032  hash (e.g., $Config{ccflags_nolargefiles}) so the extensions that are
1033  having problems can try configuring themselves without the
1034  largefileness.  This is admittedly not a clean solution, and the
1035  solution may not even work at all.  One potential failure is whether
1036  one can (or, if one can, whether it's a good idea) link together at
1037  all binaries with different ideas about file offsets, all this is
1038  platform-dependent.
1039  
1040  =head2 The Compiler Suite Is Still Experimental
1041  
1042  The compiler suite is slowly getting better but is nowhere near
1043  working order yet.
1044  
1045  =head1 Reporting Bugs
1046  
1047  If you find what you think is a bug, you might check the articles
1048  recently posted to the comp.lang.perl.misc newsgroup and the perl
1049  bug database at http://bugs.perl.org/  There may also be
1050  information at http://www.perl.com/perl/ , the Perl Home Page.
1051  
1052  If you believe you have an unreported bug, please run the B<perlbug>
1053  program included with your release.  Be sure to trim your bug down
1054  to a tiny but sufficient test case.  Your bug report, along with the
1055  output of C<perl -V>, will be sent off to perlbug@perl.org to be
1056  analysed by the Perl porting team.
1057  
1058  =head1 SEE ALSO
1059  
1060  The F<Changes> file for exhaustive details on what changed.
1061  
1062  The F<INSTALL> file for how to build Perl.
1063  
1064  The F<README> file for general stuff.
1065  
1066  The F<Artistic> and F<Copying> files for copyright information.
1067  
1068  =head1 HISTORY
1069  
1070  Written by Jarkko Hietaniemi <F<jhi@iki.fi>>, with many contributions
1071  from The Perl Porters and Perl Users submitting feedback and patches.
1072  
1073  Send omissions or corrections to <F<perlbug@perl.org>>.
1074  
1075  =cut