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This section contains a summary of the changes between the 5.6.0 release and the 5.6.1
release. More details about the changes mentioned here may be found in the Changes
files that accompany the Perl source distribution. See perlhack for pointers to online
resources where you can inspect the individual patches described by these changes.
suidperl will not run /bin/mail anymore, because some platforms have a /bin/mail that is
vulnerable to buffer overflow attacks.
Note that suidperl is neither built nor installed by default in any recent version of perl.
Use of suidperl is highly discouraged. If you think you need it, try alternatives such as sudo
first. See http://www.courtesan.com/sudo/ .
This is not an exhaustive list. It is intended to cover only the significant user-visible
changes.
UNIVERSAL::isa()
- A bug in the caching mechanism used by
UNIVERSAL::isa() that affected
base.pm has been fixed. The bug has existed since the 5.005 releases, but wasn't tickled
by base.pm in those releases.
- Memory leaks
- Various cases of memory leaks and attempts to access uninitialized memory have been
cured. See /"Known Problems" below for further
issues.
- Numeric conversions
-
Numeric conversions did not recognize changes in the string value properly in certain
circumstances.
In other situations, large unsigned numbers (those above 2**31) could sometimes lose
their unsignedness, causing bogus results in arithmetic operations.
Integer modulus on large unsigned integers sometimes returned incorrect values.
Perl 5.6.0 generated "not a number" warnings on certain conversions where
previous versions didn't.
These problems have all been rectified.
Infinity is now recognized as a number.
- qw(a\\b)
- In Perl 5.6.0, qw(a\\b) produced a string with two backslashes instead of one, in a
departure from the behavior in previous versions. The older behavior has been reinstated.
- caller()
- caller() could cause core dumps in certain situations. Carp was sometimes affected by
this problem.
- Bugs in regular expressions
-
Pattern matches on overloaded values are now handled correctly.
Perl 5.6.0 parsed m/\x{ab}/ incorrectly, leading to spurious warnings. This has been
corrected.
The RE engine found in Perl 5.6.0 accidentally pessimised certain kinds of simple
pattern matches. These are now handled better.
Regular expression debug output (whether through use re 'debug' or via -Dr)
now looks better.
Multi-line matches like "a\nxb\n" =~ /(?!\A)x/m were flawed. The
bug has been fixed.
Use of $& could trigger a core dump under some situations. This is now avoided.
Match variables $1 et al., weren't being unset when a pattern match was backtracking,
and the anomaly showed up inside /...(?{ ... }).../ etc. These variables are
now tracked correctly.
pos() did not return the correct value within s///ge in earlier versions. This is now
handled correctly.
- "slurp" mode
- readline() on files opened in "slurp" mode could return an extra ""
at the end in certain situations. This has been corrected.
- Autovivification
of symbolic references to special variables
- Autovivification of symbolic references of special variables described in perlvar (as in
${$num})
was accidentally disabled. This works again now.
- Lexical warnings
-
Lexical warnings now propagate correctly into eval "...".
use warnings qw(FATAL all) did not work as intended. This has been
corrected.
Lexical warnings could leak into other scopes in some situations. This is now fixed.
warnings::enabled() now reports the state of $^W correctly if the caller isn't using
lexical warnings.
- Spurious warnings and errors
-
Perl 5.6.0 could emit spurious warnings about redefinition of dl_error() when
statically building extensions into perl. This has been corrected.
"our" variables could result in bogus "Variable will not stay
shared" warnings. This is now fixed.
"our" variables of the same name declared in two sibling blocks resulted in
bogus warnings about "redeclaration" of the variables. The problem has been
corrected.
- glob()
-
Compatibility of the builtin glob() with old csh-based glob has been improved with the
addition of GLOB_ALPHASORT option. See File::Glob.
File::Glob::glob() has been renamed to File::Glob::bsd_glob() because the name clashes
with the builtin glob(). The older name is still available for compatibility, but is
deprecated.
Spurious syntax errors generated in certain situations, when glob() caused File::Glob
to be loaded for the first time, have been fixed.
- Tainting
-
Some cases of inconsistent taint propagation (such as within hash values) have been
fixed.
The tainting behavior of sprintf() has been rationalized. It does not taint the result
of floating point formats anymore, making the behavior consistent with that of string
interpolation.
- sort()
-
Arguments to sort() weren't being provided the right wantarray() context. The
comparison block is now run in scalar context, and the arguments to be sorted are always
provided list context.
sort() is also fully reentrant, in the sense that the sort function can itself call
sort(). This did not work reliably in previous releases.
- #line directives
- #line directives now work correctly when they appear at the very beginning of
eval
"...".
- Subroutine prototypes
- The (\&) prototype now works properly.
- map()
- map() could get pathologically slow when the result list it generates is larger than the
source list. The performance has been improved for common scenarios.
- Debugger
-
Debugger exit code now reflects the script exit code.
Condition "0" in breakpoints is now treated correctly.
The d command now checks the line number.
$. is no longer corrupted by the debugger.
All debugger output now correctly goes to the socket if RemotePort is set.
- PERL5OPT
- PERL5OPT can be set to more than one switch group. Previously, it used to be limited to
one group of options only.
- chop()
- chop(@list) in list context returned the characters chopped in reverse order. This has
been reversed to be in the right order.
- Unicode support
-
Unicode support has seen a large number of incremental improvements, but continues to
be highly experimental. It is not expected to be fully supported in the 5.6.x maintenance
releases.
substr(), join(), repeat(), reverse(), quotemeta() and string concatenation were all
handling Unicode strings incorrectly in Perl 5.6.0. This has been corrected.
Support for tr///CU and tr///UC etc., have been removed since
we realized the interface is broken. For similar functionality, see perlfunc/pack.
The Unicode Character Database has been updated to version 3.0.1 with additions made
available to the public as of August 30, 2000.
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 \s (\p{Space} isn't, since that includes the
vertical tabulator character, whereas \s doesn't.)
If you are experimenting with Unicode support in perl, the development versions of Perl
may have more to offer. In particular, I/O layers are now available in the development
track, but not in the maintenance track, primarily to do backward compatibility issues.
Unicode support is also evolving rapidly on a daily basis in the development track--the
maintenance track only reflects the most conservative of these changes.
- 64-bit support
- Support for 64-bit platforms has been improved, but continues to be experimental. The
level of support varies greatly among platforms.
- Compiler
-
The B Compiler and its various backends have had many incremental improvements, but
they continue to remain highly experimental. Use in production environments is
discouraged.
The perlcc tool has been rewritten so that the user interface is much more like that of
a C compiler.
The perlbc tools has been removed. Use perlcc -B instead.
- Lvalue subroutines
- There have been various bugfixes to support lvalue subroutines better. However, the
feature still remains experimental.
- IO::Socket
- IO::Socket::INET failed to open the specified port if the service name was not known. It
now correctly uses the supplied port number as is.
- File::Find
- File::Find now chdir()s correctly when chasing symbolic links.
- xsubpp
- xsubpp now tolerates embedded POD sections.
no Module;
no Module; does not produce an error even if Module does not have an
unimport() method. This parallels the behavior of use vis-a-vis import.
- Tests
- A large number of tests have been added.
untie() will now call an UNTIE() hook if it exists. See perltie for details.
The -DT command line switch outputs copious tokenizing information. See perlrun.
Arrays are now always interpolated in double-quotish strings. Previously, "foo@bar.com"
used to be a fatal error at compile time, if an array @bar was not used or
declared. This transitional behavior was intended to help migrate perl4 code, and is deemed to
be no longer useful. See /"Arrays
now always interpolate into double-quoted strings".
keys(), each(), pop(), push(), shift(), splice() and unshift() can all be overridden now.
my __PACKAGE__ $obj now does the expected thing.
On some systems (IRIX and Solaris among them) the system malloc is demonstrably better.
While the defaults haven't been changed in order to retain binary compatibility with earlier
releases, you may be better off building perl with Configure -Uusemymalloc ... as
discussed in the INSTALL file.
Configure has been enhanced in various ways:
README.aix, README.solaris and README.macos have been added. README.posix-bc has been
renamed to README.bs2000. These are installed as perlaix, perlsolaris, perlmacos, and perlbs2000 respectively.
The following pod documents are brand new:
perlclib Internal replacements for standard C library functions
perldebtut Perl debugging tutorial
perlebcdic Considerations for running Perl on EBCDIC platforms
perlnewmod Perl modules: preparing a new module for distribution
perlrequick Perl regular expressions quick start
perlretut Perl regular expressions tutorial
perlutil utilities packaged with the Perl distribution
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The INSTALL file has been expanded to cover various issues, such as 64-bit support.
A longer list of contributors has been added to the source distribution. See the file AUTHORS.
Numerous other changes have been made to the included documentation and FAQs.
The following modules have been added.
- B::Concise
- Walks Perl syntax tree, printing concise info about ops. See B::Concise.
- File::Temp
- Returns name and handle of a temporary file safely. See File::Temp.
- Pod::LaTeX
- Converts Pod data to formatted LaTeX. See Pod::LaTeX.
- Pod::Text::Overstrike
- Converts POD data to formatted overstrike text. See Pod::Text::Overstrike.
The following modules have been upgraded.
- CGI
- CGI v2.752 is now included.
- CPAN
- CPAN v1.59_54 is now included.
- Class::Struct
- Various bugfixes have been added.
- DB_File
- DB_File v1.75 supports newer Berkeley DB versions, among other improvements.
- Devel::Peek
- Devel::Peek has been enhanced to support dumping of memory statistics, when perl is
built with the included malloc().
- File::Find
- File::Find now supports pre and post-processing of the files in order to sort() them,
etc.
- Getopt::Long
- Getopt::Long v2.25 is included.
- IO::Poll
- Various bug fixes have been included.
- IPC::Open3
- IPC::Open3 allows use of numeric file descriptors.
- Math::BigFloat
- The fmod() function supports modulus operations. Various bug fixes have also been
included.
- Math::Complex
- Math::Complex handles inf, NaN etc., better.
- Net::Ping
- ping() could fail on odd number of data bytes, and when the echo service isn't running.
This has been corrected.
- Opcode
- A memory leak has been fixed.
- Pod::Parser
- Version 1.13 of the Pod::Parser suite is included.
- Pod::Text
- Pod::Text and related modules have been upgraded to the versions in podlators suite
v2.08.
- SDBM_File
- On dosish platforms, some keys went missing because of lack of support for files with
"holes". A workaround for the problem has been added.
- Sys::Syslog
- Various bug fixes have been included.
- Tie::RefHash
- Now supports Tie::RefHash::Nestable to automagically tie hashref values.
- Tie::SubstrHash
- Various bug fixes have been included.
The following new ports are now available.
- NCR MP-RAS
-
- NonStop-UX
-
Perl now builds under Amdahl UTS.
Perl has also been verified to build under Amiga OS.
Support for EPOC has been much improved. See README.epoc.
Building perl with -Duseithreads or -Duse5005threads now works under HP-UX 10.20
(previously it only worked under 10.30 or later). You will need a thread library package
installed. See README.hpux.
Long doubles should now work under Linux.
Mac OS Classic is now supported in the mainstream source package. See README.macos.
Support for MPE/iX has been updated. See README.mpeix.
Support for OS/2 has been improved. See os2/Changes and README.os2.
Dynamic loading on z/OS (formerly OS/390) has been improved. See README.os390.
Support for VMS has seen many incremental improvements, including better support for
operators like backticks and system(), and better %ENV handling. See README.vms
and perlvms.
Support for Stratus VOS has been improved. See vos/Changes and README.vos.
Support for Windows has been improved.
- fork() emulation has been improved in various ways, but still continues to be
experimental. See perlfork
for known bugs and caveats.
- %SIG has been enabled under USE_ITHREADS, but its use is completely unsupported under
all configurations.
- Borland C++ v5.5 is now a supported compiler that can build Perl. However, the generated
binaries continue to be incompatible with those generated by the other supported compilers
(GCC and Visual C++).
- Non-blocking waits for child processes (or pseudo-processes) are supported via
waitpid($pid,
&POSIX::WNOHANG).
- A memory leak in accept() has been fixed.
- wait(), waitpid() and backticks now return the correct exit status under Windows 9x.
- Trailing new %ENV entries weren't propagated to child processes. This is now fixed.
- Current directory entries in %ENV are now correctly propagated to child processes.
- Duping socket handles with open(F, ">&MYSOCK") now works under Windows
9x.
- The makefiles now provide a single switch to bulk-enable all the features enabled in
ActiveState ActivePerl (a popular binary distribution).
- Win32::GetCwd() correctly returns C:\ instead of C: when at the drive root. Other bugs
in chdir() and Cwd::cwd() have also been fixed.
- fork() correctly returns undef and sets EAGAIN when it runs out of pseudo-process
handles.
- ExtUtils::MakeMaker now uses $ENV{LIB} to search for libraries.
- UNC path handling is better when perl is built to support fork().
- A handle leak in socket handling has been fixed.
- send() works from within a pseudo-process.
Unless specifically qualified otherwise, the remainder of this document covers changes
between the 5.005 and 5.6.0 releases.
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