(To view the differences between the 5.6.0 release and the 5.7.0
release, see L<perl570delta>).
+=head1 Security Vulnerability Closed
+
+(This change was already made in 5.7.0 but bears repeating here.)
+
+A potential security vulnerability in the optional suidperl component
+of Perl was identified in August 2000. suidperl is neither built nor
+installed by default. As of April 2001 the only known vulnerable
+platform is Linux, most likely all Linux distributions. CERT and
+various vendors and distributors have been alerted about the vulnerability.
+See http://www.cpan.org/src/5.0/sperl-2000-08-05/sperl-2000-08-05.txt
+for more information.
+
+The problem was caused by Perl trying to report a suspected security
+exploit attempt using an external program, /bin/mail. On Linux
+platforms the /bin/mail program had an undocumented feature which
+when combined with suidperl gave access to a root shell, resulting in
+a serious compromise instead of reporting the exploit attempt. If you
+don't have /bin/mail, or if you have 'safe setuid scripts', or if
+suidperl is not installed, you are safe.
+
+The exploit attempt reporting feature has been completely removed from
+all the Perl 5.7 releases (and will be gone also from the maintenance
+release 5.6.1), so that particular vulnerability isn't there anymore.
+However, further security vulnerabilities are, unfortunately, always
+possible. The suidperl code is being reviewed and if deemed too risky
+to continue to be supported, it may be completely removed from future
+releases. In any case, suidperl should only be used by security
+experts who know exactly what they are doing and why they are using
+suidperl instead of some other solution such as sudo (see
+http://www.courtesan.com/sudo/).
+
=head1 Incompatible Changes
=over 4
Although "you shouldn't do that", it was possible to write code that
depends on Perl's hashed key order (Data::Dumper does this). The new
algorithm "One-at-a-Time" produces a different hashed key order.
-More details are in L<perldelta/Performance Enhancements>.
+More details are in L</"Performance Enhancements">.
+
+=item *
+
+The list of filenames from glob() (or <...>) is now by default sorted
+alphabetically to be csh-compliant. (bsd_glob() does still sort platform
+natively, ASCII or EBCDIC, unless GLOB_ALPHASORT is specified.)
=back
+=head1 Retired Features
+
+The use of chop() is now deprecated. This has been made easier by
+rewriting all the examples in the documentation to use chomp() instead.
+
=head1 Core Enhancements
=over 4
=item *
-Anonymous temporary files are available without need to
-'use FileHandle' or other module via
-
- open($fh,"+>", undef) || ...
+AUTOLOAD is now lvaluable.
=item *
Layers to be applied by default may be specified via the 'open' pragma.
+See L</"Installation and Configuration Improvements"> for the effects
+of PerlIO on your architecture name.
+
=item *
File handles can be marked as accepting Perl's internal encoding of Unicode
=item *
-Formats now support zero-padded decimal fields.
+Anonymous temporary files are available without need to
+'use FileHandle' or other module via
+
+ open($fh,"+>", undef) || ...
+
+That is a literal undef, not an undefined value.
=item *
the child process.
=item *
+
+The following keywords are now overrideable: chop, chomp, each, keys,
+pop, push, shift, splice, unshift.
+
+=item *
+
+Formats now support zero-padded decimal fields.
+
+=item *
+
+Perl now tries internally to use integer values in numeric conversions
+and basic arithmetics (+ - * /) if the arguments are integers, and
+tries also to keep the results stored internally as integers.
+This change leads into often slightly faster and always less lossy
+arithmetics (previously Perl always preferred floating point numbers
+in its math)
+
+=item *
The printf and sprintf now support parameter reordering using the
C<%\d+\$> and C<*\d+\$> syntaxes.
+=item *
+
+Unicode in general should be now much more usable. Unicode can be
+used in hash keys, Unicode in regular expressions should work now,
+Unicode in tr/// should work now (though tr/// seems to be a
+particularly tricky to get right, so you have been warned)
+
+=item *
+
+The Unicode Character Database coming with Perl has been upgraded
+to Unicode 3.1.
+
+=item *
+
+The Unicode character classes \p{Blank} and \p{SpacePerl} have been
+added. "Blank" is like C isblank(), that is, it contains only
+"horizontal whitespace" (the space character is, the newline isn't),
+and the "SpacePerl" is the Unicode equivalent of C<\s> (\p{Space}
+isn't, since that includes the vertical tabulator character, whereas
+C<\s> doesn't.)
+
+=back
+
+=head2 Modules and Pragmata
+
+=head2 New Modules
+
+=over 4
+
+=item *
+
+B::Concise is a new compiler backend for walking the Perl syntax tree,
+printing concise info about ops. The output is highly customizable,
+so customizable that B::Terse has been reimplemented in terms of
+B::Concise.
+
+=item *
+
+Class::ISA for reporting the search path for a class's ISA tree,
+from Sean Burke, has been added.
+
+=item *
+
+Cwd has now a split personality: if possible, an extension is used,
+(this will hopefully be both faster and more secure and robust) but
+if not possible, the familiar Perl library implementation is used.
+
+=item *
+
+Digest, a frontend module for calculating digests (checksums),
+from Gisle Aas, has been added.
+
+=item *
+
+Digest::MD5 for calculating MD5 digests (checksums), from Gisle Aas,
+has been added.
+
+NOTE: the MD5 backward compatibility module is purposefully not
+included since its use is discouraged.
+
+=item *
+
+Encode provides a mechanism to translate between different character
+encodings. Support for Unicode, ISO-8859-*, ASCII, CP*, KOI8-R, and
+three variants of EBCDIC are compiled in to the module. Several other
+encodings (like Japanese, Chinese, and MacIntosh encodings) are
+included and will be loaded at runtime.
+
+Any encoding supported by Encode module is also available to the
+":encoding()" layer if PerlIO is used.
+
+=item *
+
+Filter::Simple is an easy-to-use frontend to Filter::Util::Call,
+from Damian Conway.
+
+=item *
+
+Filter::Util::Call, from Paul Marquess, provides you with the
+framework to write I<Source Filters> in Perl. For most uses
+the frontend Filter::Simple is to be preferred.
+
+=item *
+
+Locale::Constants, Locale::Country, Locale::Currency, and Locale::Language,
+from Neil Bowers, have been added. They provide the codes for various
+locale standards, such as "fr" for France, "usd" for US Dollar, and
+"jp" for Japanese.
+
+=item *
+
+MIME::Base64, from Gisle Aas, allows you to encode data in base64.
+
+=item *
+
+MIME::QuotedPrint, from Gisle Aas, allows you to encode data in
+quoted-printable encoding.
+
+MIME::QuotedPrint has been enhanced to provide the basic methods
+necessary to use it with PerlIO::Via as in :
+
+ use MIME::QuotedPrint;
+ open($fh,">Via(MIME::QuotedPrint)",$path)
+
+=item *
+
+PerlIO::Scalar provides the IO to "in memory" perl scalars discussed
+above. It also serves as an example of a loadable layer.
+
+=item *
+
+PerlIO::Via acts as a PerlIO layer and wraps PerlIO layer
+functionality provided by a class (typically implemented in
+perl code).
+
+=item *
+
+Pod::Text::Overstrike, from Joe Smith, has been added.
+It converts POD data to formatted overstrike text.
+
+=item *
+
+Switch from Damian Conway has been added. After
+
+ use Switch;
+
+you have switch() and case() in Perl.
+
+=item *
+
+Text::Balanced from Damian Conway has been added, for
+extracting delimited text sequences from strings.
+
+=item *
+
+Tie::RefHash::Nestable, from Edward Avis, allows storing hash references
+(unlike the standard Tie::Refhash)
+
+=item *
+
+XS::Typemap is a test extension that exercizes XS typemaps.
+Nothing gets installed but for extension writers the code is
+worth studying.
+
+=back
+
+=head2 Updated And Improved Modules and Pragmata
+
+=over 4
+
+=item *
+
+B::Deparse should be now more robust (still far from providing a full
+roundtrip for any random piece of Perl code).
+
+=item *
+
+Class::Struct has now compile-time features.
+
+=item *
+
+Math::BigFloat has undergone much fixing.
+
+=item *
+
+Devel::Peek now has an interface for the Perl memory statistics
+(this works only if you are using perl's malloc, and if you have
+compiled with debugging).
+
+=item *
+
+IO::Socket has now atmark() method, which returns true if the socket
+is positioned at the out-of-band mark. The method is also exportable
+as a sockatmark() function.
+
+=item
+
+IO::Socket::INET has support for ReusePort option (if your platform
+suppport it). The Reuse option has now an alias, ReuseAddr.
+
+=item *
+
+Net::Ping has been greatly enhanced.
+
+=item *
+
+The C<open> pragma allows layers other than ":raw" and ":crlf" when
+using PerlIO.
+
+=item *
+
+POSIX::sigaction() is now much more flexible and robust.
+
+=item *
+
+The Test module has been significantly enhanced. Its use is
+greatly recommended for module writers.
+
+=item *
+
+The utf8:: name space (as in the pragma) provides various
+Perl-callable functions to provide low level access to Perl's
+internal Unicode representation. At the moment only length()
+has been implemented.
+
=back
+The following modules have been upgraded from CPAN: CPAN, CGI, DB::File,
+Getopt::Long, Pod::Man, Pod::Text, Storable, Text-Tabs+Wrap.
+
=head1 Performance Enhancements
=over 4
random number generation tests. According to perlbench, this change
has not affected the overall speed of Perl.
+=item *
+
+unshift() should now be noticeably faster.
+
=back
+=head1 Utility Changes
+
+=over 4
+
+=item *
+
+h2xs now produces template README.
+
+=item *
+
+s2p has been completely rewritten in Perl. (It is in fact a full
+implementation of sed in Perl.)
+
+=item *
+
+xsubpp now supports OUT keyword.
+
+=back
+
+=head1 New Documentation
+
+=head2 perlclib
+
+Internal replacements for standard C library functions.
+
+=head2 perliol
+
+Internals of PerlIO with layers.
+
+=head2 README.aix
+
+Documentation on compiling Perl on AIX has been added. AIX has
+several different C compilers and getting the right patchlevel
+is essential. On install README.aix will be installed as L<perlaix>.
+
+=head2 README.bs2000
+
+Documentation on compling Perl on the POSIX-BC platform (an EBCDIC
+mainframe environment) has been added.
+
+This was formerly known as README.posix-bc but the name was considered
+to be too confusing (it has nothing to do with the POSIX module or the
+POSIX standard). On install README.bs2000 will be installed as L<perlbs2000>.
+
+=head2 README.macos
+
+In perl 5.7.1 (and in the 5.6.1) the MacPerl sources have been
+synchronized with the standard Perl sources. To compile MacPerl
+some additional steps are required, and this file documents those
+steps. On install README.macos will be installed as L<perlmacos>.
+
+=head2 README.mpeix
+
+The README.mpeix has been podified, which means that this information
+about compiling and using Perl on the MPE/iX miniframe platform will
+on install be installed as L<perlmpeix>.
+
+=head2 README.solaris
+
+README.solaris has been created and Solaris wisdom from elsewhere
+in the Perl documentation has been collected there. On install
+README.solaris will be installed as L<perlsolaris>.
+
+=head2 README.vos
+
+The README.vos has been podified, which means that this information
+about compiling and using Perl on the Stratus VOS miniframe platform will
+on install be installed as L<perlvos>.
+
+=head2 Porting/repository.pod
+
+Documentation on how to use the Perl source repository has been added.
+
+=head1 Performance Enhancements
+
=head1 Installation and Configuration Improvements
+Because PerlIO is now the default on most platforms, "-perlio" doesn't
+get appended to the $Config{archname} (also known as $^O) anymore.
+Instead, if you explicitly choose not to use perlio (Configure command
+line option -Uuseperlio), you will get "-stdio" appended.
+
+Another change related to the architecture name is that "-64all"
+(-Duse64bitall, or "maximally 64-bit") is appended only if your pointers
+are 64 bits wide.
+
+APPLLIB_EXP, a less-know configuration-time definition, has been
+documented. It can be used to prepend site-specific directories
+to Perl's default search path (@INC), see INSTALL for information.
+
+Building Berkeley DB3 for compatibility modes for DB, NDBM, and ODBM
+has been documented in INSTALL.
+
+If you are on IRIX or Tru64 platforms, new profiling/debugging options
+have been added, see L</perlhack> for more information about pixie and
+Third Degree.
+
+=head2 New Or Improved Platforms
+
+=over 4
+
+=item *
+
+AIX dynamic loading should be now better supported.
+
+=item *
+
+AmigaOS has been verified to be happy with Perl after a long pause.
+
+=item *
+
+MacOS Classic (MacPerl has of course been available since
+perl 5.004 but now the source code bases of standard Perl
+and MacPerl have been synchronised)
+
+=item *
+
+NCR MP-RAS
+
+=item *
+
+NonStop-UX
+
+=item *
+
+Amdahl UTS
+
+=item *
+
+z/OS (formerly known as OS/390, formerly known as MVS OE) has now
+support for dynamic loading. This is not selected by default,
+however, you must specify -Dusedl in the arguments of Configure.
+
+=back
+
+=head2 Generic Improvements
+
=over 4
=item *
Configure no longer includes the DBM libraries (dbm, gdbm, db, ndbm)
-when building the Perl binary. The only exception to this is SunOS 4.x,
+when building the Perl binary. The only exception to this is SunOS 4.x,
which needs them.
+=item *
+
+Some new Configure symbols, useful for extension writers: d_cmsghdr
+(for struct cmsgdhr), d_fcntl_can_lock (whether fcntl() can be used
+for file locking), d_fsync, d_getitimer(), d_getpagsz (for getpagesize(),
+though you should prefer POSIX::sysconf(_SC_PAGE_SIZE)), d_msghdr_s
+(for struct msgdhr), need_va_copy (whether one needs to use Perl_va_copy()
+to copy varargs), d_readv, d_recvmsg, d_sendmsg, sig_size (the number
+of elements in an array needed to hold all the available signals),
+d_sockatmark, d_strtoq, d_u32align (whether one needs to access
+character data aligned by U32 sized pointers), d_ualarm, d_usleep,
+d_writev.
+
+=item *
+
+Removed Configure symbols: the PDP-11 memory model settings: huge,
+large, medium, models.
+
+=item *
+
+SOCKS support is now much more robust.
+
+=item *
+
+If your file system supports symbolic links you can build Perl outside
+of the source directory by
+
+ mkdir /tmp/perl/build/directory
+ cd /tmp/perl/build/directory
+ sh /path/to/perl/source/Configure -Dmksymlinks ...
+
+This will create in /tmp/perl/build/directory a tree of symbolic links
+pointing to files in /path/to/perl/source. The original files are left
+unaffected. After Configure has finished you can just say
+
+ make all test
+
+and Perl will be built and tested, all in /tmp/perl/build/directory.
+
=back
=head1 Selected Bug Fixes
+Numerous memory leaks have been hunted down. Most importantly anonymous
+subs used to leak quite a bit.
+
=over 4
=item *
+Small unpredictactabilities in the order of DESTROYS have been
+even small.
+
+=item *
+
+mkdir() now ignores trailing slashes in the directory name,
+as mandated by POSIX.
+
+=item *
+
+The PERL5OPT environment variable didn't really work before.
+
+=item *
+
+All but the first argument of the IO syswrite() method are now optional.
+
+=item *
+
+Tie::ARRAY SPLICE method was broken.
+
+=item *
+
vec() now tries to work with characters <= 255 when possible, but it leaves
higher character values in place. In that case, if vec() was used to modify
the string, it is no longer considered to be utf8-encoded.
=back
-=head1 Core Enhancements
-
-=head2 New Modules
+=head2 Platform Specific Changes and Fixes
=over 4
=item *
-Encode provides a mechanism to translate between different character
-encodings. Support for Unicode, ISO-8859-*, ASCII, CP*, KOI8-R, and
-three variants of EBCDIC are compiled in to the module. Several other
-encodings (like Japanese, Chinese, and MacIntosh encodings) are
-included and will be loaded at runtime.
+Linux previously had problems related to sockaddrlen when using
+accept(), revcfrom() (in Perl: recv()), getpeername(), and getsockname().
=item *
-Any encoding supported by Encode module is also available to the
-":encoding()" layer if PerlIO is used.
+Previously DYNIX/ptx had problems in its Configure probe for
+non-blocking I/O.
-=item *
+=back
-PerlIO::Scalar provides the IO to "in memory" perl scalars discussed
-above. It also serves as an example of a loadable layer.
+=head1 New or Changed Diagnostics
-=item *
+Two new debugging options have been added: if you have compiled your
+Perl with debugging, you can use the -DT and -DR options to trace
+tokenizing and to add reference counts to displaying variables,
+respectively.
-PerlIO::Via acts as a PerlIO layer and wraps PerlIO layer
-functionality provided by a class (typically implemented in
-perl code).
+=over 4
=item *
-MIME::QuotedPrint has been enhanced to provide the basic methods
-necessary to use it with PerlIO::Via as in :
+If an attempt to use a (non-blessed) reference as an array element
+is made, a warning is given.
- use MIME::QuotedPrint;
- open($fh,">Via(MIME::QuotedPrint)",$path)
+=item *
+
+C<push @a;> and C<unshift @a;> (with no values to push or unshift)
+now give a warning. This may be a problem for generated and evaled
+code.
=back
-=head2 Updated And Improved Modules and Pragmata
+=head1 Changed Internals
=over 4
=item *
-The C<open> pragma allows layers other than ":raw" and ":crlf" when
-using PerlIO.
+Some new internal APIs: ptr_table_clear, ptr_table_free, sv_setref_uv.
+For the full list see L<perlapi>.
=item *
-The utf8:: name space (as in the pragma) provides various
-Perl-callable functions to provide low level access to Perl's
-internal Unicode representation.
+dTHR and djSP have been obsoleted; the former removed and the latter
+replaced with dSP.
+
+=item *
+
+Perl now uses system malloc instead of Perl malloc in all 64-bit platforms.
=back
=head1 Known Problems
+=head2 lib/b test 19
+
+The test fails in various platforms (PA64 and IA64 are known), but the
+exact cause is still being investigated.
+
+=head2 Localizing a Tied Variable Leaks Memory
+
+ use Tie::Hash;
+ tie my %tie_hash => 'Tie::StdHash';
+
+ ...
+
+ local($tie_hash{Foo}) = 1; # leaks
+
+Code like the above is known to leak memory every time the local()
+is executed.
+
+=head2 sigaction test 13 in VMS
+
+The test is known to fail, whether it's because of VMS of because
+of faulty test, is not known.
+
=head2 sprintf tests 129 and 130
The op/sprintf tests 129 and 130 are known to fail in some platforms.
something else than "1" and "-1" when formatting 0.6 and -0.6 using
the printf format "%.0f", most often they produce "0" and "-0".)
+=head2 Self-tying of Arrays and Hashes Is Forbidden
+
+Self-tying of arrays and hashes is broken in rather deep and
+hard-to-fix ways. As a stop-gap measure to avoid people from getting
+frustrated at the mysterious results (core dumps, most often) it is
+for now forbidden (you will get a fatal error even from an attempt).
+
=head1 Reporting Bugs
If you find what you think is a bug, you might check the articles
projects / p5sagit/p5-mst-13.2.git / commitdiff