perl592delta
(1)
Name
perl592delta - what is new for perl v5.9.2
Synopsis
Please see following description for synopsis
Description
Perl Programmers Reference Guide PERL592DELTA(1)
NAME
perl592delta - what is new for perl v5.9.2
DESCRIPTION
This document describes differences between the 5.9.1 and
the 5.9.2 development releases. See perl590delta and
perl591delta for the differences between 5.8.0 and 5.9.1.
Incompatible Changes
Packing and UTF-8 strings
The semantics of pack() and unpack() regarding UTF-8-encoded
data has been changed. Processing is now by default
character per character instead of byte per byte on the
underlying encoding. Notably, code that used things like
"pack("a*", $string)" to see through the encoding of string
will now simply get back the original $string. Packed
strings can also get upgraded during processing when you
store upgraded characters. You can get the old behaviour by
using "use bytes".
To be consistent with pack(), the "C0" in unpack() templates
indicates that the data is to be processed in character
mode, i.e. character by character; on the contrary, "U0" in
unpack() indicates UTF-8 mode, where the packed string is
processed in its UTF-8-encoded Unicode form on a byte by
byte basis. This is reversed with regard to perl 5.8.X.
Moreover, "C0" and "U0" can also be used in pack() templates
to specify respectively character and byte modes.
"C0" and "U0" in the middle of a pack or unpack format now
switch to the specified encoding mode, honoring parens
grouping. Previously, parens were ignored.
Also, there is a new pack() character format, "W", which is
intended to replace the old "C". "C" is kept for unsigned
chars coded as bytes in the strings internal representation.
"W" represents unsigned (logical) character values, which
can be greater than 255. It is therefore more robust when
dealing with potentially UTF-8-encoded data (as "C" will
wrap values outside the range 0..255, and not respect the
string encoding).
In practice, that means that pack formats are now encoding-
neutral, except "C".
For consistency, "A" in unpack() format now trims all
Unicode whitespace from the end of the string. Before perl
5.9.2, it used to strip only the classical ASCII space
characters.
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Miscellaneous
The internal dump output has been improved, so that non-
printable characters such as newline and backspace are
output in "\x" notation, rather than octal.
The -C option can no longer be used on the "#!" line. It
wasn't working there anyway.
Core Enhancements
Malloc wrapping
Perl can now be built to detect attempts to assign
pathologically large chunks of memory. Previously such
assignments would suffer from integer wrap-around during
size calculations causing a misallocation, which would crash
perl, and could theoretically be used for "stack smashing"
attacks. The wrapping defaults to enabled on platforms
where we know it works (most AIX configurations, BSDi,
Darwin, DEC OSF/1, FreeBSD, HP-UX, GNU Linux, OpenBSD,
Solaris, VMS and most Win32 compilers) and defaults to
disabled on other platforms.
Unicode Character Database 4.0.1
The copy of the Unicode Character Database included in Perl
5.9 has been updated to 4.0.1 from 4.0.0.
suidperl less insecure
Paul Szabo has analysed and patched "suidperl" to remove
existing known insecurities. Currently there are no known
holes in "suidperl", but previous experience shows that we
cannot be confident that these were the last. You may no
longer invoke the set uid perl directly, so to preserve
backwards compatibility with scripts that invoke
#!/usr/bin/suidperl the only set uid binary is now
"sperl5.9."n ("sperl5.9.2" for this release). "suidperl" is
installed as a hard link to "perl"; both "suidperl" and
"perl" will invoke "sperl5.9.2" automatically the set uid
binary, so this change should be completely transparent.
For new projects the core perl team would strongly recommend
that you use dedicated, single purpose security tools such
as "sudo" in preference to "suidperl".
PERLIO_DEBUG
The "PERLIO_DEBUG" environment variable has no longer any
effect for setuid scripts and for scripts run with -T.
Moreover, with a thread-enabled perl, using "PERLIO_DEBUG"
could lead to an internal buffer overflow. This has been
fixed.
Formats
In addition to bug fixes, "format"'s features have been
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enhanced. See perlform.
Unicode Character Classes
Perl's regular expression engine now contains support for
matching on the intersection of two Unicode character
classes. You can also now refer to user-defined character
classes from within other user defined character classes.
Byte-order modifiers for pack() and unpack()
There are two new byte-order modifiers, ">" (big-endian) and
"<" (little-endian), that can be appended to most pack() and
unpack() template characters and groups to force a certain
byte-order for that type or group. See "pack" in perlfunc
and perlpacktut for details.
Byte count feature in pack()
A new pack() template character, ".", returns the number of
characters read so far.
New variables
A new variable, ${^RE_DEBUG_FLAGS}, controls what debug
flags are in effect for the regular expression engine when
running under "use re "debug"". See re for details.
A new variable ${^UTF8LOCALE} indicates where a UTF-8 locale
was detected by perl at startup.
Modules and Pragmata
New modules
o "encoding::warnings", by Audrey Tang, is a module to
emit warnings whenever an ASCII character string
containing high-bit bytes is implicitly converted into
UTF-8.
o "Module::CoreList", by Richard Clamp, is a small handy
module that tells you what versions of core modules ship
with any versions of Perl 5. It comes with a command-
line frontend, "corelist".
Updated And Improved Modules and Pragmata
Dual-lived modules have been updated to be kept up-to-date
with respect to CPAN.
The dual-lived modules which contain an "_" in their version
number are actually ahead of the corresponding CPAN release.
B::Concise
"B::Concise" was significantly improved.
Socket
There is experimental support for Linux abstract Unix
domain sockets.
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Sys::Syslog
"syslog()" can now use numeric constants for facility
names and priorities, in addition to strings.
threads
Detached threads are now also supported on Windows.
Utility Changes
o The "corelist" utility is now installed with perl (see
"New modules" above).
o "h2ph" and "h2xs" have been made a bit more robust with
regard to "modern" C code.
o Several bugs have been fixed in "find2perl", regarding
"-exec" and "-eval". Also the options "-path", "-ipath"
and "-iname" have been added.
o The Perl debugger can now save all debugger commands for
sourcing later; notably, it can now emulate stepping
backwards, by restarting and rerunning all bar the last
command from a saved command history.
It can also display the parent inheritance tree of a
given class.
Perl has a new -dt command-line flag, which enables
threads support in the debugger.
Performance Enhancements
o Unicode case mappings ("/i", "lc", "uc", etc) are
faster.
o "@a = sort @a" was optimized to do in-place sort.
Likewise, "reverse sort ..." is now optimized to sort in
reverse, avoiding the generation of a temporary
intermediate list.
o Unnecessary assignments are optimised away in
my $s = undef;
my @a = ();
my %h = ();
o "map" in scalar context is now optimized.
o The regexp engine now implements the trie optimization :
it's able to factorize common prefixes and suffixes in
regular expressions. A new special variable,
${^RE_TRIE_MAXBUF}, has been added to fine-tune this
optimization.
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Installation and Configuration Improvements
Run-time customization of @INC can be enabled by passing the
"-Dusesitecustomize" flag to configure. When enabled, this
will make perl run $sitelibexp/sitecustomize.pl before
anything else. This script can then be set up to add
additional entries to @INC.
There is alpha support for relocatable @INC entries.
Perl should build on Interix and on GNU/kFreeBSD.
Selected Bug Fixes
Most of those bugs were reported in the perl 5.8.x
maintenance track. Notably, quite a few utf8 bugs were
fixed, and several memory leaks were suppressed. The
perl58Xdelta manpages have more details on them.
Development-only bug fixes include :
$Foo::_ was wrongly forced as $main::_.
New or Changed Diagnostics
A new warning, "!=~ should be !~", is emitted to prevent
this misspelling of the non-matching operator.
The warning Newline in left-justified string has been
removed.
The error Too late for "-T" option has been reformulated to
be more descriptive.
There is a new compilation error, Illegal declaration of
subroutine, for an obscure case of syntax errors.
The diagnostic output of Carp has been changed slightly, to
add a space after the comma between arguments. This makes it
much easier for tools such as web browsers to wrap it, but
might confuse any automatic tools which perform detailed
parsing of Carp output.
"perl -V" has several improvements, making it more useable
from shell scripts to get the value of configuration
variables. See perlrun for details.
Changed Internals
The perl core has been refactored and reorganised in several
places. In short, this release will not be binary
compatible with any previous perl release.
Known Problems
For threaded builds, ext/threads/shared/t/wait.t has been
reported to fail some tests on HP-UX 10.20.
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Net::Ping might fail some tests on HP-UX 11.00 with the
latest OS upgrades.
t/io/dup.t, t/io/open.t and lib/ExtUtils/t/Constant.t fail
some tests on some BSD flavours.
Plans for the next release
The current plan for perl 5.9.3 is to add CPANPLUS as a core
module. More regular expression optimizations are also in
the works.
It is planned to release a development version of perl more
frequently, i.e. each time something major changes.
Reporting Bugs
If you find what you think is a bug, you might check the
articles recently posted to the comp.lang.perl.misc
newsgroup and the perl bug database at http://bugs.perl.org/
. There may also be information at http://www.perl.org/ ,
the Perl Home Page.
If you believe you have an unreported bug, please run the
perlbug program included with your release. Be sure to trim
your bug down to a tiny but sufficient test case. Your bug
report, along with the output of "perl -V", will be sent off
to perlbug@perl.org to be analysed by the Perl porting team.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | runtime/perl-512 |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
The Changes file for exhaustive details on what changed.
The INSTALL file for how to build Perl.
The README file for general stuff.
The Artistic and Copying files for copyright information.
NOTES
This software was built from source available at
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https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://www.cpan.org/src/5.0/perl-5.12.5.tar.bz2
Further information about this software can be found on the
open source community website at http://www.perl.org/.
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