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diff --git a/contrib/perl5/Porting/pumpkin.pod b/contrib/perl5/Porting/pumpkin.pod index 335e49f..99776b5 100644 --- a/contrib/perl5/Porting/pumpkin.pod +++ b/contrib/perl5/Porting/pumpkin.pod @@ -8,8 +8,8 @@ There is no simple synopsis, yet. =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, @@ -47,93 +47,68 @@ Archives of the list are held at: =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/1000000>. 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. - -=head2 Subversions + print "You've got a new perl\n" if $^V and $^V ge v5.6.0; -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.) +You can also require particular version (or later) with: -These sub-versions can also be used as floating point numbers, so -you can do things such as + use 5.006; - print "You've got an unstable perl\n" if $] == 5.00303; +or using the new syntax available only from v5.6 onward: -You can also require particular version (or later) with + use v5.6.0; - use 5.003_03; # the "_" is optional +At some point in the future, we may need to decide what to call the +next big revision. In the .package file used by metaconfig to +generate Configure, there are two variables that might be relevant: +$baserev=5 and $package=perl5. -Sub-versions produced by the members of perl5-porters are usually -available on CPAN in the F<src/5.0/unsupported> directory. +Perl releases produced by the members of perl5-porters are usually +available on CPAN in the F<src/5.0/maint> and F<src/5.0/devel> +directories. =head2 Maintenance and Development Subversions -As an experiment, starting with version 5.004, subversions _01 through -_49 will be reserved for bug-fix maintenance releases, and subversions -_50 through _99 will be available for unstable development versions. - -The separate bug-fix track is being established to allow us an easy -way to distribute important bug fixes without waiting for the -developers to untangle all the other problems in the current -developer's release. +The first rule of maintenance work is "First, do no harm." Trial releases of bug-fix maintenance releases are announced on perl5-porters. Trial releases use the new subversion number (to avoid testers installing it over the previous release) and include a 'local -patch' entry in patchlevel.h. +patch' entry in patchlevel.h. The distribution file contains the +string C<MAINT_TRIAL> to make clear that the file is not meant for +public consumption. -Watch for announcements of maintenance subversions in -comp.lang.perl.announce. - -The first rule of maintenance work is "First, do no harm." +In general, the names of official distribution files for the public +always match the regular expression: -=head2 Why such a complicated scheme? + ^perl\d+\.(\d+)\.\d+(-MAINT_TRIAL_\d+)\.tar\.gz$ -Two reasons, really. At least. +C<$1> in the pattern is always an even number for maintenance +versions, and odd for developer releases. -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. - -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? @@ -155,7 +130,7 @@ No one was allowed to make backups unless they had the "backup pumpkin". The name has stuck. -=head1 Philosophical Issues in Patching Perl +=head1 Philosophical Issues in Patching and Porting Perl There are no absolute rules, but there are some general guidelines I have tried to follow as I apply patches to the perl sources. @@ -174,6 +149,16 @@ generalized the process of building libperl so that NeXT and SVR4 users could still get their work done, but others could build a shared libperl if they wanted to as well. +Contain your changes carefully. Assume nothing about other operating +systems, not even closely related ones. Your changes must not affect +other platforms. + +Spy shamelessly on how similar patching or porting issues have been +settled elsewhere. + +If feasible, try to keep filenames 8.3-compliant to humor those poor +souls that get joy from running Perl under such dire limitations. + =head2 Seek consensus on major changes If you are making big changes, don't do it in secret. Discuss the @@ -196,6 +181,88 @@ that the machine-specific #ifdef's may not be valid across major releases of the operating system. Further, the feature-specific tests may help out folks on another platform who have the same problem. +=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> 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. + +=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 +in C<ext/*/hints> subdirectories. + +The top level hints are Bourne-shell scripts that set, modify and +unset appropriate Configure variables, based on the Configure command +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 +miniperl has been built) and control the building of their respective +extensions. They can be used to for example manipulate compilation +and linking flags. + +=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. + +=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 (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. + +=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. + +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 We should never release a main version without testing it as a @@ -211,7 +278,7 @@ that some of those things will be just plain broken and need to be fixed, 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 @@ -219,11 +286,14 @@ patch these directly; patch the data files instead. F<Configure> and F<config_h.SH> are also automatically generated by B<metaconfig>. In general, you should patch the metaconfig units -instead of patching these files directly. However, very minor changes to -F<Configure> may be made in between major sync-ups with the metaconfig -units, which tends to be complicated operations. But be careful, this -can quickly spiral out of control. Running metaconfig is not really -hard. +instead of patching these files directly. However, very minor changes +to F<Configure> may be made in between major sync-ups with the +metaconfig units, which tends to be complicated operations. But be +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 @@ -411,6 +481,9 @@ output statements mean the patch won't apply cleanly. Long ago I 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>. + Some additional notes from Larry on this: Don't forget to regenerate perly_c.diff. @@ -520,8 +593,8 @@ things that need to be fixed in Configure. =head2 VMS-specific updates -If you have changed F<perly.y>, then you may want to update -F<vms/perly_{h,c}.vms> by running C<perl vms/vms_yfix.pl>. +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>. The Perl version number appears in several places under F<vms>. It is courteous to update these versions. For example, if you are @@ -628,6 +701,42 @@ supports dynamic loading, you can also test static loading with You can also hand-tweak your config.h to try out different #ifdef branches. +=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 5 + ./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 @@ -1008,33 +1117,6 @@ may find metaconfig's units clumsy to work with. =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 @@ -1158,18 +1240,6 @@ what I came up with off the top of my head. =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 @@ -1178,16 +1248,6 @@ the dist-users mailing list along these lines. They have been folded back into the main distribution, but various parts of the perl Configure/build/install process still assume src='.'. -=item Directory for vendor-supplied modules? - -If a vendor supplies perl, but wants to leave $siteperl and $sitearch -for the local user to use, where should the vendor put vendor-supplied -modules (such as Tk.so?) If the vendor puts them in $archlib, then -they need to be updated each time the perl version is updated. -Perhaps we need a set of libries $vendorperl and $vendorarch that -track $apiversion (like the $sitexxx directories do) rather than -just $version (like the main perl directory). - =item Hint file fixes Various hint files work around Configure problems. We ought to fix @@ -1198,47 +1258,6 @@ Configure so that most of them aren't needed. 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 @@ -1320,4 +1339,4 @@ All opinions expressed herein are those of the authorZ<>(s). =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 $ |
