=head1 DESCRIPTION
-This document attempts to begin to describe some of the
-considerations involved in patching and maintaining perl.
+This document attempts to begin to describe some of the considerations
+involved in patching, porting, and maintaining perl.
This document is still under construction, and still subject to
significant changes. Still, I hope parts of it will be useful,
The Comprehensive Perl Archive Network (or CPAN) is the place to go.
There are many mirrors, but the easiest thing to use is probably
-http://www.perl.com/CPAN/README.html , which automatically points you to a
+http://www.cpan.org/README.html , which automatically points you to a
mirror site "close" to you.
=head2 Perl5-porters mailing list
=head1 How are Perl Releases Numbered?
-Perl version numbers are floating point numbers, such as 5.004.
-(Observations about the imprecision of floating point numbers for
-representing reality probably have more relevance than you might
-imagine :-) The major version number is 5 and the '004' is the
-patchlevel. (Questions such as whether or not '004' is really a minor
-version number can safely be ignored.:)
+Beginning with v5.6.0, even versions will stand for maintenance releases
+and odd versions for development releases, i.e., v5.6.x for maintenance
+releases, and v5.7.x for development releases. Before v5.6.0, subversions
+_01 through _49 were reserved for bug-fix maintenance releases, and
+subversions _50 through _99 for unstable development versions.
-The version number is available as the magic variable $],
-and can be used in comparisons, e.g.
+For example, in v5.6.1, the revision number is 5, the version is 6,
+and 1 is the subversion.
- print "You've got an old perl\n" if $] < 5.002;
+For compatibility with the older numbering scheme the composite floating
+point version number continues to be available as the magic variable $],
+and amounts to C<$revision + $version/1000 + $subversion/100000>. This
+can still be used in comparisons.
-You can also require particular version (or later) with
+ print "You've got an old perl\n" if $] < 5.005_03;
- use 5.002;
+In addition, the version is also available as a string in $^V.
-At some point in the future, we may need to decide what to call the
-next big revision. In the .package file used by metaconfig to
-generate Configure, there are two variables that might be relevant:
-$baserev=5.0 and $package=perl5. At various times, I have suggested
-we might change them to $baserev=5.1 and $package=perl5.1 if want
-to signify a fairly major update. Or, we might want to jump to perl6.
-Let's worry about that problem when we get there.
+ print "You've got a new perl\n" if $^V and $^V ge v5.6.0;
-=head2 Subversions
+You can also require particular version (or later) with:
-In addition, there may be "developer" sub-versions available. These
-are not official releases. They may contain unstable experimental
-features, and are subject to rapid change. Such developer
-sub-versions are numbered with sub-version numbers. For example,
-version 5.003_04 is the 4'th developer version built on top of
-5.003. It might include the _01, _02, and _03 changes, but it
-also might not. Sub-versions are allowed to be subversive. (But see
-the next section for recent changes.)
+ use 5.006;
-These sub-versions can also be used as floating point numbers, so
-you can do things such as
+or using the new syntax available only from v5.6 onward:
- print "You've got an unstable perl\n" if $] == 5.00303;
+ use v5.6.0;
-You can also require particular version (or later) with
-
- use 5.003_03; # the "_" is optional
+At some point in the future, we may need to decide what to call the
+next big revision. In the .package file used by metaconfig to
+generate Configure, there are two variables that might be relevant:
+$baserev=5 and $package=perl5.
-Sub-versions produced by the members of perl5-porters are usually
-available on CPAN in the F<src/5.0/unsupported> directory.
+Perl releases produced by the members of perl5-porters are usually
+available on CPAN in the F<src/5.0/maint> and F<src/5.0/devel>
+directories.
=head2 Maintenance and Development Subversions
-As an experiment, starting with version 5.004, subversions _01 through
-_49 will be reserved for bug-fix maintenance releases, and subversions
-_50 through _99 will be available for unstable development versions.
-
-The separate bug-fix track is being established to allow us an easy
-way to distribute important bug fixes without waiting for the
-developers to untangle all the other problems in the current
-developer's release.
+The first rule of maintenance work is "First, do no harm."
Trial releases of bug-fix maintenance releases are announced on
perl5-porters. Trial releases use the new subversion number (to avoid
testers installing it over the previous release) and include a 'local
-patch' entry in patchlevel.h.
+patch' entry in patchlevel.h. The distribution file contains the
+string C<MAINT_TRIAL> to make clear that the file is not meant for
+public consumption.
-Watch for announcements of maintenance subversions in
-comp.lang.perl.announce.
+In general, the names of official distribution files for the public
+always match the regular expression:
-The first rule of maintenance work is "First, do no harm."
-
-=head2 Why such a complicated scheme?
-
-Two reasons, really. At least.
+ ^perl\d+\.(\d+)\.\d+(-MAINT_TRIAL_\d+)\.tar\.gz$
-First, we need some way to identify and release collections of patches
-that are known to have new features that need testing and exploration. The
-subversion scheme does that nicely while fitting into the
-C<use 5.004;> mold.
+C<$1> in the pattern is always an even number for maintenance
+versions, and odd for developer releases.
-Second, since most of the folks who help maintain perl do so on a
-free-time voluntary basis, perl development does not proceed at a
-precise pace, though it always seems to be moving ahead quickly.
-We needed some way to pass around the "patch pumpkin" to allow
-different people chances to work on different aspects of the
-distribution without getting in each other's way. It wouldn't be
-constructive to have multiple people working on incompatible
-implementations of the same idea. Instead what was needed was
-some kind of "baton" or "token" to pass around so everyone knew
-whose turn was next.
+In the past it has been observed that pumkings tend to invent new
+naming conventions on the fly. If you are a pumpking, before you
+invent a new name for any of the three types of perl distributions,
+please inform the guys from the CPAN who are doing indexing and
+provide the trees of symlinks and the like. They will have to know
+I<in advance> what you decide.
=head2 Why is it called the patch pumpkin?
If feasible, try to keep filenames 8.3-compliant to humor those poor
souls that get joy from running Perl under such dire limitations.
+There's a script, check83.pl, for keeping your nose 8.3-clean.
=head2 Seek consensus on major changes
=head2 Machine-specific files
+=over 4
+
+=item source code
+
If you have many machine-specific #defines or #includes, consider
creating an "osish.h" (os2ish.h, vmsish.h, and so on) and including
that in perl.h. If you have several machine-specific files (function
emulations, function stubs, build utility wrappers) you may create a
separate subdirectory (djgpp, win32) and put the files in there.
-Remember to update C<MANIFEST>.
+Remember to update C<MANIFEST> when you add files.
+
+If your system supports dynamic loading but none of the existing
+methods at F<ext/DynaLoader/dl_*.xs> work for you, you must write
+a new one. Study the existing ones to see what kind of interface
+you must supply.
-=head2 Machine-specific hints
+=item build hints
There are two kinds of hints: hints for building Perl and hints for
extensions. The former live in the C<hints> subdirectory, the latter
line options and possibly existing config.sh and Policy.sh files from
previous Configure runs.
-The extension hints are written Perl (by the time they are used
+The extension hints are written in Perl (by the time they are used
miniperl has been built) and control the building of their respective
extensions. They can be used to for example manipulate compilation
and linking flags.
-=head2 Machine-specific tests
+=item build and installation Makefiles, scripts, and so forth
+
+Sometimes you will also need to tweak the Perl build and installation
+procedure itself, like for example F<Makefile.SH> and F<installperl>.
+Tread very carefully, even more than usual. Contain your changes
+with utmost care.
-Some of the tests in C<t> subdirectory assume machine-specific things
+=item test suite
+
+Many of the tests in C<t> subdirectory assume machine-specific things
like existence of certain functions, something about filesystem
semantics, certain external utilities and their error messages. Use
the C<$^O> and the C<Config> module (which contains the results of the
Configure run, in effect the C<config.sh> converted to Perl) to either
-skip or customize the tests for your platform.
+skip (preferably not) or customize (preferable) the tests for your
+platform.
+
+=item modules
+
+Certain standard modules may need updating if your operating system
+sports for example a native filesystem naming. You may want to update
+some or all of the modules File::Basename, File::Spec, File::Path, and
+File::Copy to become aware of your native filesystem syntax and
+peculiarities.
+
+Remember to have a $VERSION in the modules. You can use the
+Porting/checkVERSION.pl script for checking this.
+
+=item documentation
+
+If your operating system comes from outside UNIX you almost certainly
+will have differences in the available operating system functionality
+(missing system calls, different semantics, whatever). Please
+document these at F<pod/perlport.pod>. If your operating system is
+the first B<not> to have a system call also update the list of
+"portability-bewares" at the beginning of F<pod/perlfunc.pod>.
+
+A file called F<README.youros> at the top level that explains things
+like how to install perl at this platform, where to get any possibly
+required additional software, and for example what test suite errors
+to expect, is nice too. Such files are in the process of being written
+in pod format and will eventually be renamed F<INSTALL.youros>.
+
+You may also want to write a separate F<.pod> file for your operating
+system to tell about existing mailing lists, os-specific modules,
+documentation, whatever. Please name these along the lines of
+F<perl>I<youros>.pod. [unfinished: where to put this file (the pod/
+subdirectory, of course: but more importantly, which/what index files
+should be updated?)]
+
+=back
=head2 Allow for lots of testing
but, in general, we ought to try to avoid breaking widely-installed
things.
-=head2 Automate generation of derivative files
+=head2 Automated generation of derivative files
The F<embed.h>, F<keywords.h>, F<opcode.h>, and F<perltoc.pod> files
are all automatically generated by perl scripts. In general, don't
careful, this can quickly spiral out of control. Running metaconfig
is not really hard.
+Also F<Makefile> is automatically produced from F<Makefile.SH>.
+In general, look out for all F<*.SH> files.
+
Finally, the sample files in the F<Porting/> subdirectory are
generated automatically by the script F<U/mksample> included
with the metaconfig units. See L<"run metaconfig"> below for
that comes with Perl's metaconfig units. Perl's metaconfig units
should be available on CPAN. A set of units that will work with
perl5.005 is in the file F<mc_units-5.005_00-01.tar.gz> under
-http://www.perl.com/CPAN/authors/id/ANDYD/ . The mc_units tar file
+http://www.cpan.org/authors/id/ANDYD/ . The mc_units tar file
should be unpacked in your main perl source directory. Note: those
units were for use with 5.005. There may have been changes since then.
Check for later versions or contact perl5-porters@perl.org to obtain a
to config.sh and then propoagate them to a canned 'config.h' by any
number of means, including a perl script in win32/ or carrying
config.sh and config_h.SH to a Unix system and running sh
-config_h.SH.)
+config_h.SH.) Vms uses configure.com to generate its own config.sh
+and config.h. If you want to add a new variable to config.sh check
+with vms folk how to add it to configure.com too.
XXX]
The Porting/config.sh and Porting/config_H files are provided to
Simply edit the existing config_H file; keep the first few explanatory
lines and then copy your new config.h below.
-It may also be necessary to update win32/config.?c, vms/config.vms and
+It may also be necessary to update win32/config.?c, and
plan9/config.plan9, though you should be quite careful in doing so if
you are not familiar with those systems. You might want to issue your
patch with a promise to quickly issue a follow-up that handles those
started to fix F<perly.fixer> to detect this, but I never completed the
task.
-If C<perly.c> changes, make sure you run C<perl vms/vms_yfix.pl> to
-update the corresponding VMS files. See L<VMS-specific updates>.
+If C<perly.c> or C<perly.h> changes, make sure you run C<perl vms/vms_yfix.pl>
+to update the corresponding VMS files. This could be taken care of by
+the regen_all target in the Unix Makefile. See also
+L<VMS-specific updates>.
Some additional notes from Larry on this:
Larry
+=head2 make regen_all
+
+This target takes care of the PERLYVMS, regen_headers, and regen_pods
+targets.
+
=head2 make regen_headers
The F<embed.h>, F<keywords.h>, and F<opcode.h> files are all automatically
than answering all the questions and complaints about the failing
command.
+=head2 make regen_pods
+
+Will run `make regen_pods` in the pod directory for indexing.
+
=head2 global.sym, interp.sym and perlio.sym
Make sure these files are up-to-date. Read the comments in these
If you do change F<global.sym> or F<interp.sym>, think carefully about
what you are doing. To the extent reasonable, we'd like to maintain
-souce and binary compatibility with older releases of perl. That way,
+source and binary compatibility with older releases of perl. That way,
extensions built under one version of perl will continue to work with
new versions of perl.
=head2 VMS-specific updates
If you have changed F<perly.y> or F<perly.c>, then you most probably want
-to update F<vms/perly_{h,c}.vms> by running C<perl vms/vms_yfix.pl>.
+to update F<vms/perly_{h,c}.vms> by running C<perl vms/vms_yfix.pl>, or
+by running `make regen_all` which will run that script for you.
-The Perl version number appears in several places under F<vms>.
-It is courteous to update these versions. For example, if you are
-making 5.004_42, replace "5.00441" with "5.00442".
+The Perl revision number appears as "perl5" in configure.com.
+It is courteous to update that if necessary.
=head2 Making the new distribution
I find the F<makepatch> utility quite handy for making patches.
You can obtain it from any CPAN archive under
-http://www.perl.com/CPAN/authors/Johan_Vromans/ . There are a couple
+http://www.cpan.org/authors/Johan_Vromans/ . There are a couple
of differences between my version and the standard one. I have mine do
a
You can also hand-tweak your config.h to try out different #ifdef
branches.
+=head2 Other tests
+
+=over 4
+
+=item CHECK_FORMAT
+
+To test the correct use of printf-style arguments, C<Configure> with
+S<-Dccflags='-DCHECK_FORMAT -Wformat'> and run C<make>. The compiler
+will produce warning of incorrect use of format arguments. CHECK_FORMAT
+changes perl-defined formats to common formats, so DO NOT USE the executable
+produced by this process.
+
+A more accurate approach is the following commands:
+
+=over 4
+
+=item *
+
+build miniperl with -DCHECK_FORMAT
+
+ make clean
+ make miniperl OPTIMIZE=-DCHECK_FORMAT >& mini.log
+
+=item *
+
+build a clean miniperl,
+and build everything else from that with -DCHECK_FORMAT
+
+ make clean
+ make miniperl
+ make all OPTIMIZE=-DCHECK_FORMAT >& make.log
+
+=item *
+
+clean up, and print warnings from the log files
+
+ make clean
+ perl -nwe 'print if /^\S+:/ and not /^make\b/' \
+ mini.log make.log
+
+=back
+
+(-Wformat support by Robin Barker.)
+
+=back
+
+=head1 Running Purify
+
+Purify is a commercial tool that is helpful in identifying memory
+overruns, wild pointers, memory leaks and other such badness. Perl
+must be compiled in a specific way for optimal testing with Purify.
+
+Use the following commands to test perl with Purify:
+
+ sh Configure -des -Doptimize=-g -Uusemymalloc -Dusemultiplicity \
+ -Accflags=-DPURIFY
+ setenv PURIFYOPTIONS "-chain-length=25"
+ make all pureperl
+ cd t
+ ln -s ../pureperl perl
+ setenv PERL_DESTRUCT_LEVEL 2
+ ./perl TEST
+
+Disabling Perl's malloc allows Purify to monitor allocations and leaks
+more closely; using Perl's malloc will make Purify report most leaks
+in the "potential" leaks category. Enabling the multiplicity option
+allows perl to clean up thoroughly when the interpreter shuts down, which
+reduces the number of bogus leak reports from Purify. The -DPURIFY
+enables any Purify-specific debugging code in the sources.
+
+Purify outputs messages in "Viewer" windows by default. If you don't have
+a windowing environment or if you simply want the Purify output to
+unobtrusively go to a log file instead of to the interactive window,
+use the following options instead:
+
+ setenv PURIFYOPTIONS "-chain-length=25 -windows=no -log-file=perl.log \
+ -append-logfile=yes"
+
+The only currently known leaks happen when there are compile-time errors
+within eval or require. (Fixing these is non-trivial, unfortunately, but
+they must be fixed eventually.)
+
=head1 Common Gotcha's
=over 4
=item Metaconfig worked for me
-My system at the time was Interactive 2.2, a SVR3.2/386 derivative that
+My system at the time was Interactive 2.2, an SVR3.2/386 derivative that
also had some POSIX support. Metaconfig-generated Configure scripts
worked fine for me on that system. On the other hand, autoconf-generated
scripts usually didn't. (They did come quite close, though, in some
=back
-=head2 @INC search order
-
-By default, the list of perl library directories in @INC is the
-following:
-
- $archlib
- $privlib
- $sitearch
- $sitelib
-
-Specifically, on my Solaris/x86 system, I run
-B<sh Configure -Dprefix=/opt/perl> and I have the following
-directories:
-
- /opt/perl/lib/i86pc-solaris/5.00307
- /opt/perl/lib
- /opt/perl/lib/site_perl/i86pc-solaris
- /opt/perl/lib/site_perl
-
-That is, perl's directories come first, followed by the site-specific
-directories.
-
-The site libraries come second to support the usage of extensions
-across perl versions. Read the relevant section in F<INSTALL> for
-more information. If we ever make $sitearch version-specific, this
-topic could be revisited.
-
=head2 Why isn't there a directory to override Perl's library?
Mainly because no one's gotten around to making one. Note that
=head1 Upload Your Work to CPAN
You can upload your work to CPAN if you have a CPAN id. Check out
-http://www.perl.com/CPAN/modules/04pause.html for information on
+http://www.cpan.org/modules/04pause.html for information on
_PAUSE_, the Perl Author's Upload Server.
I typically upload both the patch file, e.g. F<perl5.004_08.pat.gz>
If you want your patch to appear in the F<src/5.0/unsupported>
directory on CPAN, send e-mail to the CPAN master librarian. (Check
-out http://www.perl.com/CPAN/CPAN.html ).
+out http://www.cpan.org/CPAN.html ).
=head1 Help Save the World
=over 4
-=item installprefix
-
-I think we ought to support
-
- Configure -Dinstallprefix=/blah/blah
-
-Currently, we support B<-Dprefix=/blah/blah>, but the changing the install
-location has to be handled by something like the F<config.over> trick
-described in F<INSTALL>. AFS users also are treated specially.
-We should probably duplicate the metaconfig prefix stuff for an
-install prefix.
-
=item Configure -Dsrc=/blah/blah
We should be able to emulate B<configure --srcdir>. Tom Tromey
Some of the hint file information (particularly dynamic loading stuff)
ought to be fed back into the main metaconfig distribution.
-=item Catch GNU Libc "Stub" functions
-
-Some functions (such as lchown()) are present in libc, but are
-unimplmented. That is, they always fail and set errno=ENOSYS.
-
-Thomas Bushnell provided the following sample code and the explanation
-that follows:
-
- /* System header to define __stub macros and hopefully few prototypes,
- which can conflict with char FOO(); below. */
- #include <assert.h>
- /* Override any gcc2 internal prototype to avoid an error. */
- /* We use char because int might match the return type of a gcc2
- builtin and then its argument prototype would still apply. */
- char FOO();
-
- int main() {
-
- /* The GNU C library defines this for functions which it implements
- to always fail with ENOSYS. Some functions are actually named
- something starting with __ and the normal name is an alias. */
- #if defined (__stub_FOO) || defined (__stub___FOO)
- choke me
- #else
- FOO();
- #endif
-
- ; return 0; }
-
-The choice of <assert.h> is essentially arbitrary. The GNU libc
-macros are found in <gnu/stubs.h>. You can include that file instead
-of <assert.h> (which itself includes <gnu/stubs.h>) if you test for
-its existence first. <assert.h> is assumed to exist on every system,
-which is why it's used here. Any GNU libc header file will include
-the stubs macros. If either __stub_NAME or __stub___NAME is defined,
-then the function doesn't actually exist. Tests using <assert.h> work
-on every system around.
-
-The declaration of FOO is there to override builtin prototypes for
-ANSI C functions.
-
=back
=head2 Probably good ideas waiting for round tuits
=item File locking
Somehow, straighten out, document, and implement lockf(), flock(),
-and/or fcntl() file locking. It's a mess.
+and/or fcntl() file locking. It's a mess. See $d_fcntl_can_lock
+in recent config.sh files though.
=back
=head1 LAST MODIFIED
-$Id: pumpkin.pod,v 1.22 1998/07/22 16:33:55 doughera Released $
+$Id: pumpkin.pod,v 1.23 2000/01/13 19:45:13 doughera Released $
https://perl5.git.perl.org / perl5.git / blobdiff