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1=head1 NAME
2
e25f343d 3Pumpkin - Notes on handling the Perl Patch Pumpkin And Porting Perl
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4
5=head1 SYNOPSIS
6
7There is no simple synopsis, yet.
8
9=head1 DESCRIPTION
10
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11This document attempts to begin to describe some of the considerations
12involved in patching, porting, and maintaining perl.
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13
14This document is still under construction, and still subject to
15significant changes. Still, I hope parts of it will be useful,
16so I'm releasing it even though it's not done.
17
18For the most part, it's a collection of anecdotal information that
19already assumes some familiarity with the Perl sources. I really need
20an introductory section that describes the organization of the sources
21and all the various auxiliary files that are part of the distribution.
22
23=head1 Where Do I Get Perl Sources and Related Material?
24
25The Comprehensive Perl Archive Network (or CPAN) is the place to go.
26There are many mirrors, but the easiest thing to use is probably
a93751fa 27http://www.cpan.org/README.html , which automatically points you to a
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28mirror site "close" to you.
29
30=head2 Perl5-porters mailing list
31
32The mailing list perl5-porters@perl.org
33is the main group working with the development of perl. If you're
34interested in all the latest developments, you should definitely
35subscribe. The list is high volume, but generally has a
36fairly low noise level.
37
38Subscribe by sending the message (in the body of your letter)
39
40 subscribe perl5-porters
41
42to perl5-porters-request@perl.org .
43
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44Archives of the list are held at:
45
f38c94f4 46 http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
fb73857a 47
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48=head1 How are Perl Releases Numbered?
49
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50Beginning with v5.6.0, even versions will stand for maintenance releases
51and odd versions for development releases, i.e., v5.6.x for maintenance
52releases, and v5.7.x for development releases. Before v5.6.0, subversions
53_01 through _49 were reserved for bug-fix maintenance releases, and
54subversions _50 through _99 for unstable development versions.
7b5757d1 55
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56For example, in v5.6.1, the revision number is 5, the version is 6,
57and 1 is the subversion.
aa689395 58
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59For compatibility with the older numbering scheme the composite floating
60point version number continues to be available as the magic variable $],
76ba0908 61and amounts to C<$revision + $version/1000 + $subversion/100000>. This
f5a32c7f 62can still be used in comparisons.
aa689395 63
f5a32c7f 64 print "You've got an old perl\n" if $] < 5.005_03;
aa689395 65
f5a32c7f 66In addition, the version is also available as a string in $^V.
aa689395 67
f5a32c7f 68 print "You've got a new perl\n" if $^V and $^V ge v5.6.0;
7b5757d1 69
f5a32c7f 70You can also require particular version (or later) with:
aa689395 71
f5a32c7f 72 use 5.006;
aa689395 73
f5a32c7f 74or using the new syntax available only from v5.6 onward:
aa689395 75
f5a32c7f 76 use v5.6.0;
aa689395 77
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78At some point in the future, we may need to decide what to call the
79next big revision. In the .package file used by metaconfig to
80generate Configure, there are two variables that might be relevant:
81$baserev=5 and $package=perl5.
aa689395 82
f5a32c7f 83Perl releases produced by the members of perl5-porters are usually
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84available on CPAN in the F<src/5.0/maint> and F<src/5.0/devel>
85directories.
aa689395 86
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87=head2 Maintenance and Development Subversions
88
f5a32c7f 89The first rule of maintenance work is "First, do no harm."
7b5757d1 90
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91Trial releases of bug-fix maintenance releases are announced on
92perl5-porters. Trial releases use the new subversion number (to avoid
93testers installing it over the previous release) and include a 'local
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94patch' entry in patchlevel.h. The distribution file contains the
95string C<MAINT_TRIAL> to make clear that the file is not meant for
96public consumption.
fb73857a 97
e04b929a 98In general, the names of official distribution files for the public
f5a32c7f 99always match the regular expression:
e04b929a 100
f5a32c7f 101 ^perl\d+\.(\d+)\.\d+(-MAINT_TRIAL_\d+)\.tar\.gz$
e04b929a 102
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103C<$1> in the pattern is always an even number for maintenance
104versions, and odd for developer releases.
e04b929a 105
efc41c8e 106In the past it has been observed that pumpkings tend to invent new
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107naming conventions on the fly. If you are a pumpking, before you
108invent a new name for any of the three types of perl distributions,
109please inform the guys from the CPAN who are doing indexing and
110provide the trees of symlinks and the like. They will have to know
111I<in advance> what you decide.
20f245af 112
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113=head2 Why is it called the patch pumpkin?
114
115Chip Salzenberg gets credit for that, with a nod to his cow orker,
116David Croy. We had passed around various names (baton, token, hot
117potato) but none caught on. Then, Chip asked:
118
119[begin quote]
120
121 Who has the patch pumpkin?
122
123To explain: David Croy once told me once that at a previous job,
124there was one tape drive and multiple systems that used it for backups.
125But instead of some high-tech exclusion software, they used a low-tech
126method to prevent multiple simultaneous backups: a stuffed pumpkin.
127No one was allowed to make backups unless they had the "backup pumpkin".
128
129[end quote]
130
131The name has stuck.
132
a6968aa6 133=head1 Philosophical Issues in Patching and Porting Perl
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134
135There are no absolute rules, but there are some general guidelines I
136have tried to follow as I apply patches to the perl sources.
137(This section is still under construction.)
138
139=head2 Solve problems as generally as possible
140
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141Never implement a specific restricted solution to a problem when you
142can solve the same problem in a more general, flexible way.
143
144For example, for dynamic loading to work on some SVR4 systems, we had
145to build a shared libperl.so library. In order to build "FAT" binaries
146on NeXT 4.0 systems, we had to build a special libperl library. Rather
147than continuing to build a contorted nest of special cases, I
148generalized the process of building libperl so that NeXT and SVR4 users
149could still get their work done, but others could build a shared
150libperl if they wanted to as well.
aa689395 151
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152Contain your changes carefully. Assume nothing about other operating
153systems, not even closely related ones. Your changes must not affect
154other platforms.
155
156Spy shamelessly on how similar patching or porting issues have been
157settled elsewhere.
158
159If feasible, try to keep filenames 8.3-compliant to humor those poor
160souls that get joy from running Perl under such dire limitations.
9e371ce5 161There's a script, check83.pl, for keeping your nose 8.3-clean.
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162In a similar vein, do not create files or directories which differ only
163in case (upper versus lower).
a6968aa6 164
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165=head2 Seek consensus on major changes
166
167If you are making big changes, don't do it in secret. Discuss the
168ideas in advance on perl5-porters.
169
170=head2 Keep the documentation up-to-date
171
172If your changes may affect how users use perl, then check to be sure
173that the documentation is in sync with your changes. Be sure to
174check all the files F<pod/*.pod> and also the F<INSTALL> document.
175
176Consider writing the appropriate documentation first and then
7b5757d1 177implementing your change to correspond to the documentation.
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178
179=head2 Avoid machine-specific #ifdef's
180
181To the extent reasonable, try to avoid machine-specific #ifdef's in
182the sources. Instead, use feature-specific #ifdef's. The reason is
183that the machine-specific #ifdef's may not be valid across major
184releases of the operating system. Further, the feature-specific tests
185may help out folks on another platform who have the same problem.
186
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187=head2 Machine-specific files
188
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189=over 4
190
191=item source code
192
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193If you have many machine-specific #defines or #includes, consider
194creating an "osish.h" (os2ish.h, vmsish.h, and so on) and including
195that in perl.h. If you have several machine-specific files (function
196emulations, function stubs, build utility wrappers) you may create a
197separate subdirectory (djgpp, win32) and put the files in there.
98dddfbd 198Remember to update C<MANIFEST> when you add files.
a6968aa6 199
ff935051 200If your system supports dynamic loading but none of the existing
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201methods at F<ext/DynaLoader/dl_*.xs> work for you, you must write
202a new one. Study the existing ones to see what kind of interface
203you must supply.
204
205=item build hints
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206
207There are two kinds of hints: hints for building Perl and hints for
208extensions. The former live in the C<hints> subdirectory, the latter
209in C<ext/*/hints> subdirectories.
210
211The top level hints are Bourne-shell scripts that set, modify and
212unset appropriate Configure variables, based on the Configure command
213line options and possibly existing config.sh and Policy.sh files from
214previous Configure runs.
215
76ba0908 216The extension hints are written in Perl (by the time they are used
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217miniperl has been built) and control the building of their respective
218extensions. They can be used to for example manipulate compilation
219and linking flags.
220
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221=item build and installation Makefiles, scripts, and so forth
222
223Sometimes you will also need to tweak the Perl build and installation
224procedure itself, like for example F<Makefile.SH> and F<installperl>.
225Tread very carefully, even more than usual. Contain your changes
226with utmost care.
a6968aa6 227
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228=item test suite
229
230Many of the tests in C<t> subdirectory assume machine-specific things
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231like existence of certain functions, something about filesystem
232semantics, certain external utilities and their error messages. Use
233the C<$^O> and the C<Config> module (which contains the results of the
234Configure run, in effect the C<config.sh> converted to Perl) to either
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235skip (preferably not) or customize (preferable) the tests for your
236platform.
237
238=item modules
239
240Certain standard modules may need updating if your operating system
241sports for example a native filesystem naming. You may want to update
242some or all of the modules File::Basename, File::Spec, File::Path, and
243File::Copy to become aware of your native filesystem syntax and
244peculiarities.
245
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246Remember to have a $VERSION in the modules. You can use the
247Porting/checkVERSION.pl script for checking this.
248
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249=item documentation
250
251If your operating system comes from outside UNIX you almost certainly
252will have differences in the available operating system functionality
253(missing system calls, different semantics, whatever). Please
254document these at F<pod/perlport.pod>. If your operating system is
255the first B<not> to have a system call also update the list of
256"portability-bewares" at the beginning of F<pod/perlfunc.pod>.
257
258A file called F<README.youros> at the top level that explains things
259like how to install perl at this platform, where to get any possibly
260required additional software, and for example what test suite errors
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261to expect, is nice too. Such files are in the process of being written
262in pod format and will eventually be renamed F<INSTALL.youros>.
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263
264You may also want to write a separate F<.pod> file for your operating
265system to tell about existing mailing lists, os-specific modules,
266documentation, whatever. Please name these along the lines of
267F<perl>I<youros>.pod. [unfinished: where to put this file (the pod/
268subdirectory, of course: but more importantly, which/what index files
269should be updated?)]
270
271=back
a6968aa6 272
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273=head2 Allow for lots of testing
274
275We should never release a main version without testing it as a
276subversion first.
277
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278=head2 Test popular applications and modules.
279
280We should never release a main version without testing whether or not
281it breaks various popular modules and applications. A partial list of
282such things would include majordomo, metaconfig, apache, Tk, CGI,
283libnet, and libwww, to name just a few. Of course it's quite possible
284that some of those things will be just plain broken and need to be fixed,
285but, in general, we ought to try to avoid breaking widely-installed
286things.
287
98dddfbd 288=head2 Automated generation of derivative files
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289
290The F<embed.h>, F<keywords.h>, F<opcode.h>, and F<perltoc.pod> files
291are all automatically generated by perl scripts. In general, don't
292patch these directly; patch the data files instead.
293
294F<Configure> and F<config_h.SH> are also automatically generated by
295B<metaconfig>. In general, you should patch the metaconfig units
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296instead of patching these files directly. However, very minor changes
297to F<Configure> may be made in between major sync-ups with the
298metaconfig units, which tends to be complicated operations. But be
299careful, this can quickly spiral out of control. Running metaconfig
300is not really hard.
aa689395 301
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302Also F<Makefile> is automatically produced from F<Makefile.SH>.
303In general, look out for all F<*.SH> files.
304
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305Finally, the sample files in the F<Porting/> subdirectory are
306generated automatically by the script F<U/mksample> included
307with the metaconfig units. See L<"run metaconfig"> below for
308information on obtaining the metaconfig units.
309
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310=head1 How to Make a Distribution
311
312There really ought to be a 'make dist' target, but there isn't.
313The 'dist' suite of tools also contains a number of tools that I haven't
314learned how to use yet. Some of them may make this all a bit easier.
315
316Here are the steps I go through to prepare a patch & distribution.
317
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318Lots of it could doubtless be automated but isn't. The Porting/makerel
319(make release) perl script does now help automate some parts of it.
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320
321=head2 Announce your intentions
322
323First, you should volunteer out loud to take the patch pumpkin. It's
324generally counter-productive to have multiple people working in secret
325on the same thing.
326
327At the same time, announce what you plan to do with the patch pumpkin,
328to allow folks a chance to object or suggest alternatives, or do it for
329you. Naturally, the patch pumpkin holder ought to incorporate various
330bug fixes and documentation improvements that are posted while he or
331she has the pumpkin, but there might also be larger issues at stake.
332
333One of the precepts of the subversion idea is that we shouldn't give
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334the patch pumpkin to anyone unless we have some idea what he or she
335is going to do with it.
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336
337=head2 refresh pod/perltoc.pod
338
339Presumably, you have done a full C<make> in your working source
340directory. Before you C<make spotless> (if you do), and if you have
341changed any documentation in any module or pod file, change to the
342F<pod> directory and run C<make toc>.
343
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344=head2 run installhtml to check the validity of the pod files
345
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346=head2 update patchlevel.h
347
348Don't be shy about using the subversion number, even for a relatively
349modest patch. We've never even come close to using all 99 subversions,
350and it's better to have a distinctive number for your patch. If you
351need feedback on your patch, go ahead and issue it and promise to
352incorporate that feedback quickly (e.g. within 1 week) and send out a
353second patch.
354
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355If you update the subversion number, you may need to change the version
356number near the top of the F<Changes> file.
357
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358=head2 run metaconfig
359
360If you need to make changes to Configure or config_h.SH, it may be best to
361change the appropriate metaconfig units instead, and regenerate Configure.
362
363 metaconfig -m
364
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365will regenerate Configure and config_h.SH. Much more information
366on obtaining and running metaconfig is in the F<U/README> file
367that comes with Perl's metaconfig units. Perl's metaconfig units
368should be available on CPAN. A set of units that will work with
369perl5.005 is in the file F<mc_units-5.005_00-01.tar.gz> under
a93751fa 370http://www.cpan.org/authors/id/ANDYD/ . The mc_units tar file
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371should be unpacked in your main perl source directory. Note: those
372units were for use with 5.005. There may have been changes since then.
d562869c 373Check for later versions or contact perl5-porters@perl.org to obtain a
20f245af 374pointer to the current version.
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375
376Alternatively, do consider if the F<*ish.h> files might be a better
377place for your changes.
378
379=head2 MANIFEST
380
381Make sure the MANIFEST is up-to-date. You can use dist's B<manicheck>
382program for this. You can also use
383
3e3baf6d 384 perl -w -MExtUtils::Manifest=fullcheck -e fullcheck
aa689395 385
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386Both commands will also list extra files in the directory that are not
387listed in MANIFEST.
aa689395 388
bfb7748a 389The MANIFEST is normally sorted.
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390
391If you are using metaconfig to regenerate Configure, then you should note
392that metaconfig actually uses MANIFEST.new, so you want to be sure
393MANIFEST.new is up-to-date too. I haven't found the MANIFEST/MANIFEST.new
394distinction particularly useful, but that's probably because I still haven't
395learned how to use the full suite of tools in the dist distribution.
396
397=head2 Check permissions
398
399All the tests in the t/ directory ought to be executable. The
400main makefile used to do a 'chmod t/*/*.t', but that resulted in
401a self-modifying distribution--something some users would strongly
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402prefer to avoid. The F<t/TEST> script will check for this
403and do the chmod if needed, but the tests still ought to be
404executable.
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405
406In all, the following files should probably be executable:
407
408 Configure
409 configpm
32fcaa0b 410 configure.gnu
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411 embed.pl
412 installperl
413 installman
414 keywords.pl
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415 myconfig
416 opcode.pl
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417 t/TEST
418 t/*/*.t
419 *.SH
420 vms/ext/Stdio/test.pl
421 vms/ext/filespec.t
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422 x2p/*.SH
423
424Other things ought to be readable, at least :-).
425
426Probably, the permissions for the files could be encoded in MANIFEST
427somehow, but I'm reluctant to change MANIFEST itself because that
428could break old scripts that use MANIFEST.
429
430I seem to recall that some SVR3 systems kept some sort of file that listed
431permissions for system files; something like that might be appropriate.
432
433=head2 Run Configure
434
435This will build a config.sh and config.h. You can skip this if you haven't
693762b4 436changed Configure or config_h.SH at all. I use the following command
aa689395 437
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438 sh Configure -Dprefix=/opt/perl -Doptimize=-O -Dusethreads \
439 -Dcf_by='yourname' \
440 -Dcf_email='yourname@yourhost.yourplace.com' \
441 -Dperladmin='yourname@yourhost.yourplace.com' \
442 -Dmydomain='.yourplace.com' \
443 -Dmyhostname='yourhost' \
444 -des
aa689395 445
693762b4 446=head2 Update Porting/config.sh and Porting/config_H
dfe9444c 447
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448[XXX
449This section needs revision. We're currently working on easing
450the task of keeping the vms, win32, and plan9 config.sh info
451up-to-date. The plan is to use keep up-to-date 'canned' config.sh
452files in the appropriate subdirectories and then generate 'canned'
453config.h files for vms, win32, etc. from the generic config.sh file.
454This is to ease maintenance. When Configure gets updated, the parts
455sometimes get scrambled around, and the changes in config_H can
456sometimes be very hard to follow. config.sh, on the other hand, can
457safely be sorted, so it's easy to track (typically very small) changes
458to config.sh and then propoagate them to a canned 'config.h' by any
459number of means, including a perl script in win32/ or carrying
460config.sh and config_h.SH to a Unix system and running sh
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461config_h.SH.) Vms uses configure.com to generate its own config.sh
462and config.h. If you want to add a new variable to config.sh check
463with vms folk how to add it to configure.com too.
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464XXX]
465
466The Porting/config.sh and Porting/config_H files are provided to
467help those folks who can't run Configure. It is important to keep
468them up-to-date. If you have changed config_h.SH, those changes must
469be reflected in config_H as well. (The name config_H was chosen to
470distinguish the file from config.h even on case-insensitive file systems.)
471Simply edit the existing config_H file; keep the first few explanatory
472lines and then copy your new config.h below.
aa689395 473
76ba0908 474It may also be necessary to update win32/config.?c, and
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475plan9/config.plan9, though you should be quite careful in doing so if
476you are not familiar with those systems. You might want to issue your
477patch with a promise to quickly issue a follow-up that handles those
478directories.
479
0de566d7 480=head2 make regen_perly
aa689395 481
0de566d7 482If perly.y has been edited, it is nessary to run this target to rebuild
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483perly.h, perly.act and perly.tab. In fact this target just runs the Perl
484script regen_perly.pl. Note that perly.c is I<not> rebuilt; this is just a
0de566d7 485plain static file now.
aa689395 486
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487This target relies on you having Bison installed on your system. Running
488the target will tell you if you haven't got the right version, and if so,
489where to get the right one. Or if you prefer, you could hack
490regen_perly.pl to work with your version of Bison. The important things
491are that the regexes can still extract out the right chunks of the Bison
d21142e6 492output into perly.act and perly.tab, and that the contents of those two
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493files, plus perly.h, are functionally equivalent to those produced by the
494supported version of Bison.
ebb99254 495
0de566d7 496Note that in the old days, you had to do C<make run_byacc> instead.
aa689395 497
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498=head2 make regen_all
499
0de566d7 500This target takes care of the regen_headers, and regen_pods targets.
76ba0908 501
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502=head2 make regen_headers
503
504The F<embed.h>, F<keywords.h>, and F<opcode.h> files are all automatically
505generated by perl scripts. Since the user isn't guaranteed to have a
506working perl, we can't require the user to generate them. Hence you have
507to, if you're making a distribution.
508
509I used to include rules like the following in the makefile:
510
511 # The following three header files are generated automatically
512 # The correct versions should be already supplied with the perl kit,
513 # in case you don't have perl or 'sh' available.
514 # The - is to ignore error return codes in case you have the source
515 # installed read-only or you don't have perl yet.
516 keywords.h: keywords.pl
517 @echo "Don't worry if this fails."
518 - perl keywords.pl
519
520
7b5757d1 521However, I got B<lots> of mail consisting of people worrying because the
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522command failed. I eventually decided that I would save myself time
523and effort by manually running C<make regen_headers> myself rather
524than answering all the questions and complaints about the failing
525command.
526
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527=head2 make regen_pods
528
529Will run `make regen_pods` in the pod directory for indexing.
530
3e3baf6d 531=head2 global.sym, interp.sym and perlio.sym
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532
533Make sure these files are up-to-date. Read the comments in these
534files and in perl_exp.SH to see what to do.
535
536=head2 Binary compatibility
537
538If you do change F<global.sym> or F<interp.sym>, think carefully about
539what you are doing. To the extent reasonable, we'd like to maintain
76ba0908 540source and binary compatibility with older releases of perl. That way,
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541extensions built under one version of perl will continue to work with
542new versions of perl.
543
544Of course, some incompatible changes may well be necessary. I'm just
545suggesting that we not make any such changes without thinking carefully
546about them first. If possible, we should provide
547backwards-compatibility stubs. There's a lot of XS code out there.
548Let's not force people to keep changing it.
549
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550=head2 PPPort
551
552F<ext/Devel/PPPort/PPPort.pm> needs to be synchronized to include all
553new macros added to .h files (normally perl.h and XSUB.h, but others
554as well). Since chances are that when a new macro is added the
555committer will forget to update F<PPPort.pm>, it's the best to diff for
556changes in .h files when making a new release and making sure that
557F<PPPort.pm> contains them all.
558
559The pumpking can delegate the synchronization responsibility to anybody
560else, but the release process is the only place where we can make sure
561that no new macros fell through the cracks.
562
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563=head2 Changes
564
565Be sure to update the F<Changes> file. Try to include both an overall
566summary as well as detailed descriptions of the changes. Your
3e3baf6d 567audience will include other developers and users, so describe
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568user-visible changes (if any) in terms they will understand, not in
569code like "initialize foo variable in bar function".
570
571There are differing opinions on whether the detailed descriptions
572ought to go in the Changes file or whether they ought to be available
573separately in the patch file (or both). There is no disagreement that
574detailed descriptions ought to be easily available somewhere.
575
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576If you update the subversion number in F<patchlevel.h>, you may need
577to change the version number near the top of the F<Changes> file.
578
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579=head2 Todo
580
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581The F<pod/perltodo.pod> file contains a roughly-categorized unordered
582list of aspects of Perl that could use enhancement, features that could
583be added, areas that could be cleaned up, and so on. During your term
584as pumpkin-holder, you will probably address some of these issues, and
585perhaps identify others which, while you decide not to address them this
586time around, may be tackled in the future. Update the file to reflect
587the situation as it stands when you hand over the pumpkin.
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588
589You might like, early in your pumpkin-holding career, to see if you
590can find champions for partiticular issues on the to-do list: an issue
591owned is an issue more likely to be resolved.
592
94655993 593There are also some more porting-specific L</Todo> items later in this
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594file.
595
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596=head2 OS/2-specific updates
597
598In the os2 directory is F<diff.configure>, a set of OS/2-specific
599diffs against B<Configure>. If you make changes to Configure, you may
600want to consider regenerating this diff file to save trouble for the
601OS/2 maintainer.
602
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603You can also consider the OS/2 diffs as reminders of portability
604things that need to be fixed in Configure.
605
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606=head2 VMS-specific updates
607
76ba0908
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608The Perl revision number appears as "perl5" in configure.com.
609It is courteous to update that if necessary.
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610
611=head2 Making the new distribution
612
613Suppose, for example, that you want to make version 5.004_08. Then you can
614do something like the following
615
616 mkdir ../perl5.004_08
617 awk '{print $1}' MANIFEST | cpio -pdm ../perl5.004_08
618 cd ../
619 tar cf perl5.004_08.tar perl5.004_08
620 gzip --best perl5.004_08.tar
621
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622These steps, with extra checks, are automated by the Porting/makerel
623script.
624
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625=head2 Making a new patch
626
627I find the F<makepatch> utility quite handy for making patches.
628You can obtain it from any CPAN archive under
a93751fa 629http://www.cpan.org/authors/Johan_Vromans/ . There are a couple
3e3baf6d
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630of differences between my version and the standard one. I have mine do
631a
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632
633 # Print a reassuring "End of Patch" note so people won't
634 # wonder if their mailer truncated patches.
635 print "\n\nEnd of Patch.\n";
636
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637at the end. That's because I used to get questions from people asking
638if their mail was truncated.
639
640It also writes Index: lines which include the new directory prefix
641(change Index: print, approx line 294 or 310 depending on the version,
642to read: print PATCH ("Index: $newdir$new\n");). That helps patches
643work with more POSIX conformant patch programs.
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644
645Here's how I generate a new patch. I'll use the hypothetical
6465.004_07 to 5.004_08 patch as an example.
647
648 # unpack perl5.004_07/
649 gzip -d -c perl5.004_07.tar.gz | tar -xof -
650 # unpack perl5.004_08/
651 gzip -d -c perl5.004_08.tar.gz | tar -xof -
652 makepatch perl5.004_07 perl5.004_08 > perl5.004_08.pat
653
654Makepatch will automatically generate appropriate B<rm> commands to remove
655deleted files. Unfortunately, it will not correctly set permissions
656for newly created files, so you may have to do so manually. For example,
657patch 5.003_04 created a new test F<t/op/gv.t> which needs to be executable,
658so at the top of the patch, I inserted the following lines:
659
660 # Make a new test
661 touch t/op/gv.t
662 chmod +x t/opt/gv.t
663
664Now, of course, my patch is now wrong because makepatch didn't know I
665was going to do that command, and it patched against /dev/null.
666
667So, what I do is sort out all such shell commands that need to be in the
668patch (including possible mv-ing of files, if needed) and put that in the
669shell commands at the top of the patch. Next, I delete all the patch parts
670of perl5.004_08.pat, leaving just the shell commands. Then, I do the
671following:
672
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673 cd perl5.004_07
674 sh ../perl5.004_08.pat
aa689395 675 cd ..
7b5757d1 676 makepatch perl5.004_07 perl5.004_08 >> perl5.004_08.pat
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677
678(Note the append to preserve my shell commands.)
679Now, my patch will line up with what the end users are going to do.
680
681=head2 Testing your patch
682
683It seems obvious, but be sure to test your patch. That is, verify that
684it produces exactly the same thing as your full distribution.
685
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686 rm -rf perl5.004_07
687 gzip -d -c perl5.004_07.tar.gz | tar -xf -
688 cd perl5.004_07
689 sh ../perl5.004_08.pat
690 patch -p1 -N < ../perl5.004_08.pat
aa689395 691 cd ..
7b5757d1 692 gdiff -r perl5.004_07 perl5.004_08
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693
694where B<gdiff> is GNU diff. Other diff's may also do recursive checking.
695
696=head2 More testing
697
698Again, it's obvious, but you should test your new version as widely as you
699can. You can be sure you'll hear about it quickly if your version doesn't
700work on both ANSI and pre-ANSI compilers, and on common systems such as
701SunOS 4.1.[34], Solaris, and Linux.
702
703If your changes include conditional code, try to test the different
704branches as thoroughly as you can. For example, if your system
705supports dynamic loading, you can also test static loading with
706
707 sh Configure -Uusedl
708
709You can also hand-tweak your config.h to try out different #ifdef
710branches.
711
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712=head2 Other tests
713
714=over 4
715
716=item CHECK_FORMAT
717
506c03b2
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718If you have gcc, you can test the correct use of printf-style
719arguments. Run C<Configure> with S<-Dccflags='-DCHECK_FORMAT
720-Wformat'> (and S<-Dcc=gcc>, if you are not on a system where C<cc>
721is C<gcc>) and run C<make>. The compiler will produce warnings of
722incorrect use of format arguments. CHECK_FORMAT changes perl-defined
723formats to common formats, so DO NOT USE the executable produced by
724this process.
d2560b70
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725
726A more accurate approach is the following commands:
727
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728=over 4
729
730=item *
731
732build miniperl with -DCHECK_FORMAT
733
734 make clean
735 make miniperl OPTIMIZE=-DCHECK_FORMAT >& mini.log
736
737=item *
738
739build a clean miniperl,
740and build everything else from that with -DCHECK_FORMAT
741
d2560b70 742 make clean
b3fe4827 743 make miniperl
436c6dd3 744 make all OPTIMIZE='-DCHECK_FORMAT -Wformat' >& make.log
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745
746=item *
747
748clean up, and print warnings from the log files
749
d2560b70 750 make clean
b3fe4827
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751 perl -nwe 'print if /^\S+:/ and not /^make\b/' \
752 mini.log make.log
753
754=back
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755
756(-Wformat support by Robin Barker.)
757
93189314
JH
758=item gcc -ansi -pedantic
759
760Configure -Dgccansipedantic [ -Dcc=gcc ] will enable (via the cflags script,
761not $Config{ccflags}) the gcc strict ANSI C flags -ansi and -pedantic for
762the compilation of the core files on platforms where it knows it can
763do so (like Linux, see cflags.SH for the full list), and on some
764platforms only one (Solaris can do only -pedantic, not -ansi).
765The flag -DPERL_GCC_PEDANTIC also gets added, since gcc does not add
766any internal cpp flag to signify that -pedantic is being used, as it
767does for -ansi (__STRICT_ANSI__).
768
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769Note that the -ansi and -pedantic are enabled only for version 3 (and
770later) of gcc, since even gcc version 2.95.4 finds lots of seemingly
771false "value computed not used" errors from Perl.
772
93189314
JH
773The -ansi and -pedantic are useful in catching at least the following
774nonportable practices:
775
776=over 4
777
778=item *
779
780gcc-specific extensions
781
782=item *
783
784lvalue casts
785
786=item *
787
788// C++ comments
789
790=item *
791
792enum trailing commas
793
794=back
795
796The -Dgccansipedantic should be used only when cleaning up the code,
797not for production builds, since otherwise gcc cannot inline certain
798things.
799
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800=back
801
d33b2eba 802=head1 Running Purify
f5a32c7f
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803
804Purify is a commercial tool that is helpful in identifying memory
805overruns, wild pointers, memory leaks and other such badness. Perl
806must be compiled in a specific way for optimal testing with Purify.
807
808Use the following commands to test perl with Purify:
809
810 sh Configure -des -Doptimize=-g -Uusemymalloc -Dusemultiplicity \
811 -Accflags=-DPURIFY
812 setenv PURIFYOPTIONS "-chain-length=25"
813 make all pureperl
814 cd t
815 ln -s ../pureperl perl
365a6279 816 setenv PERL_DESTRUCT_LEVEL 2
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GS
817 ./perl TEST
818
819Disabling Perl's malloc allows Purify to monitor allocations and leaks
820more closely; using Perl's malloc will make Purify report most leaks
821in the "potential" leaks category. Enabling the multiplicity option
822allows perl to clean up thoroughly when the interpreter shuts down, which
823reduces the number of bogus leak reports from Purify. The -DPURIFY
824enables any Purify-specific debugging code in the sources.
825
826Purify outputs messages in "Viewer" windows by default. If you don't have
827a windowing environment or if you simply want the Purify output to
828unobtrusively go to a log file instead of to the interactive window,
829use the following options instead:
830
831 setenv PURIFYOPTIONS "-chain-length=25 -windows=no -log-file=perl.log \
832 -append-logfile=yes"
833
834The only currently known leaks happen when there are compile-time errors
835within eval or require. (Fixing these is non-trivial, unfortunately, but
836they must be fixed eventually.)
837
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838=head1 Common Gotcha's
839
840=over 4
841
842=item #elif
843
844The '#elif' preprocessor directive is not understood on all systems.
845Specifically, I know that Pyramids don't understand it. Thus instead of the
846simple
847
848 #if defined(I_FOO)
849 # include <foo.h>
850 #elif defined(I_BAR)
851 # include <bar.h>
852 #else
853 # include <fubar.h>
854 #endif
855
856You have to do the more Byzantine
857
858 #if defined(I_FOO)
859 # include <foo.h>
860 #else
861 # if defined(I_BAR)
862 # include <bar.h>
863 # else
864 # include <fubar.h>
865 # endif
866 #endif
867
868Incidentally, whitespace between the leading '#' and the preprocessor
869command is not guaranteed, but is very portable and you may use it freely.
870I think it makes things a bit more readable, especially once things get
871rather deeply nested. I also think that things should almost never get
872too deeply nested, so it ought to be a moot point :-)
873
874=item Probably Prefer POSIX
875
876It's often the case that you'll need to choose whether to do
877something the BSD-ish way or the POSIX-ish way. It's usually not
878a big problem when the two systems use different names for similar
879functions, such as memcmp() and bcmp(). The perl.h header file
880handles these by appropriate #defines, selecting the POSIX mem*()
881functions if available, but falling back on the b*() functions, if
882need be.
883
884More serious is the case where some brilliant person decided to
885use the same function name but give it a different meaning or
886calling sequence :-). getpgrp() and setpgrp() come to mind.
887These are a real problem on systems that aim for conformance to
888one standard (e.g. POSIX), but still try to support the other way
889of doing things (e.g. BSD). My general advice (still not really
890implemented in the source) is to do something like the following.
891Suppose there are two alternative versions, fooPOSIX() and
892fooBSD().
893
894 #ifdef HAS_FOOPOSIX
895 /* use fooPOSIX(); */
896 #else
897 # ifdef HAS_FOOBSD
898 /* try to emulate fooPOSIX() with fooBSD();
899 perhaps with the following: */
900 # define fooPOSIX fooBSD
901 # else
902 # /* Uh, oh. We have to supply our own. */
903 # define fooPOSIX Perl_fooPOSIX
904 # endif
905 #endif
906
907=item Think positively
908
909If you need to add an #ifdef test, it is usually easier to follow if you
910think positively, e.g.
911
912 #ifdef HAS_NEATO_FEATURE
913 /* use neato feature */
914 #else
915 /* use some fallback mechanism */
916 #endif
917
918rather than the more impenetrable
919
920 #ifndef MISSING_NEATO_FEATURE
921 /* Not missing it, so we must have it, so use it */
922 #else
923 /* Are missing it, so fall back on something else. */
924 #endif
925
926Of course for this toy example, there's not much difference. But when
927the #ifdef's start spanning a couple of screen fulls, and the #else's
928are marked something like
929
930 #else /* !MISSING_NEATO_FEATURE */
931
932I find it easy to get lost.
933
934=item Providing Missing Functions -- Problem
935
936Not all systems have all the neat functions you might want or need, so
937you might decide to be helpful and provide an emulation. This is
938sound in theory and very kind of you, but please be careful about what
939you name the function. Let me use the C<pause()> function as an
940illustration.
941
942Perl5.003 has the following in F<perl.h>
943
944 #ifndef HAS_PAUSE
945 #define pause() sleep((32767<<16)+32767)
946 #endif
947
948Configure sets HAS_PAUSE if the system has the pause() function, so
949this #define only kicks in if the pause() function is missing.
950Nice idea, right?
951
952Unfortunately, some systems apparently have a prototype for pause()
953in F<unistd.h>, but don't actually have the function in the library.
954(Or maybe they do have it in a library we're not using.)
955
956Thus, the compiler sees something like
957
958 extern int pause(void);
959 /* . . . */
960 #define pause() sleep((32767<<16)+32767)
961
962and dies with an error message. (Some compilers don't mind this;
963others apparently do.)
964
965To work around this, 5.003_03 and later have the following in perl.h:
966
967 /* Some unistd.h's give a prototype for pause() even though
968 HAS_PAUSE ends up undefined. This causes the #define
969 below to be rejected by the compiler. Sigh.
970 */
971 #ifdef HAS_PAUSE
972 # define Pause pause
973 #else
974 # define Pause() sleep((32767<<16)+32767)
975 #endif
976
977This works.
978
979The curious reader may wonder why I didn't do the following in
980F<util.c> instead:
981
982 #ifndef HAS_PAUSE
983 void pause()
984 {
985 sleep((32767<<16)+32767);
986 }
987 #endif
988
989That is, since the function is missing, just provide it.
990Then things would probably be been alright, it would seem.
991
992Well, almost. It could be made to work. The problem arises from the
993conflicting needs of dynamic loading and namespace protection.
994
995For dynamic loading to work on AIX (and VMS) we need to provide a list
996of symbols to be exported. This is done by the script F<perl_exp.SH>,
997which reads F<global.sym> and F<interp.sym>. Thus, the C<pause>
998symbol would have to be added to F<global.sym> So far, so good.
999
1000On the other hand, one of the goals of Perl5 is to make it easy to
1001either extend or embed perl and link it with other libraries. This
1002means we have to be careful to keep the visible namespace "clean".
1003That is, we don't want perl's global variables to conflict with
1004those in the other application library. Although this work is still
1005in progress, the way it is currently done is via the F<embed.h> file.
1006This file is built from the F<global.sym> and F<interp.sym> files,
1007since those files already list the globally visible symbols. If we
1008had added C<pause> to global.sym, then F<embed.h> would contain the
1009line
1010
1011 #define pause Perl_pause
1012
1013and calls to C<pause> in the perl sources would now point to
1014C<Perl_pause>. Now, when B<ld> is run to build the F<perl> executable,
1015it will go looking for C<perl_pause>, which probably won't exist in any
1016of the standard libraries. Thus the build of perl will fail.
1017
1018Those systems where C<HAS_PAUSE> is not defined would be ok, however,
1019since they would get a C<Perl_pause> function in util.c. The rest of
1020the world would be in trouble.
1021
1022And yes, this scenario has happened. On SCO, the function C<chsize>
1023is available. (I think it's in F<-lx>, the Xenix compatibility
1024library.) Since the perl4 days (and possibly before), Perl has
1025included a C<chsize> function that gets called something akin to
1026
1027 #ifndef HAS_CHSIZE
1028 I32 chsize(fd, length)
1029 /* . . . */
1030 #endif
1031
1032When 5.003 added
1033
1034 #define chsize Perl_chsize
1035
1036to F<embed.h>, the compile started failing on SCO systems.
1037
1038The "fix" is to give the function a different name. The one
1039implemented in 5.003_05 isn't optimal, but here's what was done:
1040
1041 #ifdef HAS_CHSIZE
1042 # ifdef my_chsize /* Probably #defined to Perl_my_chsize in embed.h */
1043 # undef my_chsize
1044 # endif
1045 # define my_chsize chsize
1046 #endif
1047
1048My explanatory comment in patch 5.003_05 said:
1049
1050 Undef and then re-define my_chsize from Perl_my_chsize to
1051 just plain chsize if this system HAS_CHSIZE. This probably only
1052 applies to SCO. This shows the perils of having internal
1053 functions with the same name as external library functions :-).
1054
1055Now, we can safely put C<my_chsize> in F<global.sym>, export it, and
1056hide it with F<embed.h>.
1057
1058To be consistent with what I did for C<pause>, I probably should have
1059called the new function C<Chsize>, rather than C<my_chsize>.
1060However, the perl sources are quite inconsistent on this (Consider
1061New, Mymalloc, and Myremalloc, to name just a few.)
1062
1063There is a problem with this fix, however, in that C<Perl_chsize>
1064was available as a F<libperl.a> library function in 5.003, but it
1065isn't available any more (as of 5.003_07). This means that we've
1066broken binary compatibility. This is not good.
1067
1068=item Providing missing functions -- some ideas
1069
1070We currently don't have a standard way of handling such missing
1071function names. Right now, I'm effectively thinking aloud about a
1072solution. Some day, I'll try to formally propose a solution.
1073
1074Part of the problem is that we want to have some functions listed as
1075exported but not have their names mangled by embed.h or possibly
1076conflict with names in standard system headers. We actually already
1077have such a list at the end of F<perl_exp.SH> (though that list is
1078out-of-date):
1079
1080 # extra globals not included above.
1081 cat <<END >> perl.exp
1082 perl_init_ext
1083 perl_init_fold
1084 perl_init_i18nl14n
1085 perl_alloc
1086 perl_construct
1087 perl_destruct
1088 perl_free
1089 perl_parse
1090 perl_run
1091 perl_get_sv
1092 perl_get_av
1093 perl_get_hv
1094 perl_get_cv
1095 perl_call_argv
1096 perl_call_pv
1097 perl_call_method
1098 perl_call_sv
1099 perl_requirepv
1100 safecalloc
1101 safemalloc
1102 saferealloc
1103 safefree
1104
1105This still needs much thought, but I'm inclined to think that one
1106possible solution is to prefix all such functions with C<perl_> in the
1107source and list them along with the other C<perl_*> functions in
1108F<perl_exp.SH>.
1109
1110Thus, for C<chsize>, we'd do something like the following:
1111
1112 /* in perl.h */
1113 #ifdef HAS_CHSIZE
1114 # define perl_chsize chsize
1115 #endif
1116
1117then in some file (e.g. F<util.c> or F<doio.c>) do
1118
1119 #ifndef HAS_CHSIZE
1120 I32 perl_chsize(fd, length)
1121 /* implement the function here . . . */
1122 #endif
1123
1124Alternatively, we could just always use C<chsize> everywhere and move
1125C<chsize> from F<global.sym> to the end of F<perl_exp.SH>. That would
1126probably be fine as long as our C<chsize> function agreed with all the
1127C<chsize> function prototypes in the various systems we'll be using.
1128As long as the prototypes in actual use don't vary that much, this is
1129probably a good alternative. (As a counter-example, note how Configure
1130and perl have to go through hoops to find and use get Malloc_t and
1131Free_t for C<malloc> and C<free>.)
1132
1133At the moment, this latter option is what I tend to prefer.
1134
1135=item All the world's a VAX
1136
1137Sorry, showing my age:-). Still, all the world is not BSD 4.[34],
1138SVR4, or POSIX. Be aware that SVR3-derived systems are still quite
1139common (do you have any idea how many systems run SCO?) If you don't
1140have a bunch of v7 manuals handy, the metaconfig units (by default
1141installed in F</usr/local/lib/dist/U>) are a good resource to look at
1142for portability.
1143
1144=back
1145
1146=head1 Miscellaneous Topics
1147
1148=head2 Autoconf
1149
1150Why does perl use a metaconfig-generated Configure script instead of an
1151autoconf-generated configure script?
1152
1153Metaconfig and autoconf are two tools with very similar purposes.
1154Metaconfig is actually the older of the two, and was originally written
1155by Larry Wall, while autoconf is probably now used in a wider variety of
1156packages. The autoconf info file discusses the history of autoconf and
1157how it came to be. The curious reader is referred there for further
1158information.
1159
1160Overall, both tools are quite good, I think, and the choice of which one
1161to use could be argued either way. In March, 1994, when I was just
1162starting to work on Configure support for Perl5, I considered both
1163autoconf and metaconfig, and eventually decided to use metaconfig for the
1164following reasons:
1165
1166=over 4
1167
1168=item Compatibility with Perl4
1169
1170Perl4 used metaconfig, so many of the #ifdef's were already set up for
1171metaconfig. Of course metaconfig had evolved some since Perl4's days,
1172but not so much that it posed any serious problems.
1173
1174=item Metaconfig worked for me
1175
d1be9408 1176My system at the time was Interactive 2.2, an SVR3.2/386 derivative that
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1177also had some POSIX support. Metaconfig-generated Configure scripts
1178worked fine for me on that system. On the other hand, autoconf-generated
1179scripts usually didn't. (They did come quite close, though, in some
1180cases.) At the time, I actually fetched a large number of GNU packages
1181and checked. Not a single one configured and compiled correctly
1182out-of-the-box with the system's cc compiler.
1183
1184=item Configure can be interactive
1185
1186With both autoconf and metaconfig, if the script works, everything is
1187fine. However, one of my main problems with autoconf-generated scripts
1188was that if it guessed wrong about something, it could be B<very> hard to
1189go back and fix it. For example, autoconf always insisted on passing the
1190-Xp flag to cc (to turn on POSIX behavior), even when that wasn't what I
1191wanted or needed for that package. There was no way short of editing the
1192configure script to turn this off. You couldn't just edit the resulting
1193Makefile at the end because the -Xp flag influenced a number of other
1194configure tests.
1195
1196Metaconfig's Configure scripts, on the other hand, can be interactive.
1197Thus if Configure is guessing things incorrectly, you can go back and fix
1198them. This isn't as important now as it was when we were actively
1199developing Configure support for new features such as dynamic loading,
1200but it's still useful occasionally.
1201
1202=item GPL
1203
1204At the time, autoconf-generated scripts were covered under the GNU Public
1205License, and hence weren't suitable for inclusion with Perl, which has a
1206different licensing policy. (Autoconf's licensing has since changed.)
1207
1208=item Modularity
1209
1210Metaconfig builds up Configure from a collection of discrete pieces
1211called "units". You can override the standard behavior by supplying your
1212own unit. With autoconf, you have to patch the standard files instead.
1213I find the metaconfig "unit" method easier to work with. Others
1214may find metaconfig's units clumsy to work with.
1215
1216=back
1217
aa689395
PP
1218=head2 Why isn't there a directory to override Perl's library?
1219
1220Mainly because no one's gotten around to making one. Note that
1221"making one" involves changing perl.c, Configure, config_h.SH (and
1222associated files, see above), and I<documenting> it all in the
1223INSTALL file.
1224
1225Apparently, most folks who want to override one of the standard library
1226files simply do it by overwriting the standard library files.
1227
1228=head2 APPLLIB
1229
1230In the perl.c sources, you'll find an undocumented APPLLIB_EXP
1231variable, sort of like PRIVLIB_EXP and ARCHLIB_EXP (which are
1232documented in config_h.SH). Here's what APPLLIB_EXP is for, from
1233a mail message from Larry:
1234
1235 The main intent of APPLLIB_EXP is for folks who want to send out a
1236 version of Perl embedded in their product. They would set the symbol
1237 to be the name of the library containing the files needed to run or to
1238 support their particular application. This works at the "override"
1239 level to make sure they get their own versions of any library code that
1240 they absolutely must have configuration control over.
1241
1242 As such, I don't see any conflict with a sysadmin using it for a
1243 override-ish sort of thing, when installing a generic Perl. It should
1244 probably have been named something to do with overriding though. Since
1245 it's undocumented we could still change it... :-)
1246
24f415b4
AD
1247Given that it's already there, you can use it to override distribution modules.
1248One way to do that is to add
1249
453a1e5f 1250 ccflags="$ccflags -DAPPLLIB_EXP=\"/my/override\""
24f415b4
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1251
1252to your config.over file. (You have to be particularly careful to get the
453a1e5f
MB
1253double quotes in. APPLLIB_EXP must be a valid C string. It might
1254actually be easier to just #define it yourself in perl.c.)
24f415b4
AD
1255
1256Then perl.c will put /my/override ahead of ARCHLIB and PRIVLIB. Perl will
1257also search architecture-specific and version-specific subdirectories of
1258APPLLIB_EXP.
aa689395 1259
c4f23d77
AD
1260=head2 Shared libperl.so location
1261
1262Why isn't the shared libperl.so installed in /usr/lib/ along
1263with "all the other" shared libraries? Instead, it is installed
1264in $archlib, which is typically something like
1265
1266 /usr/local/lib/perl5/archname/5.00404
1267
1268and is architecture- and version-specific.
1269
1270The basic reason why a shared libperl.so gets put in $archlib is so that
1271you can have more than one version of perl on the system at the same time,
1272and have each refer to its own libperl.so.
1273
1274Three examples might help. All of these work now; none would work if you
1275put libperl.so in /usr/lib.
1276
1277=over
1278
1279=item 1.
1280
1281Suppose you want to have both threaded and non-threaded perl versions
1282around. Configure will name both perl libraries "libperl.so" (so that
1283you can link to them with -lperl). The perl binaries tell them apart
1284by having looking in the appropriate $archlib directories.
1285
1286=item 2.
1287
1288Suppose you have perl5.004_04 installed and you want to try to compile
1289it again, perhaps with different options or after applying a patch.
1290If you already have libperl.so installed in /usr/lib/, then it may be
1291either difficult or impossible to get ld.so to find the new libperl.so
1292that you're trying to build. If, instead, libperl.so is tucked away in
1293$archlib, then you can always just change $archlib in the current perl
1294you're trying to build so that ld.so won't find your old libperl.so.
1295(The INSTALL file suggests you do this when building a debugging perl.)
1296
1297=item 3.
1298
1299The shared perl library is not a "well-behaved" shared library with
1300proper major and minor version numbers, so you can't necessarily
1301have perl5.004_04 and perl5.004_05 installed simultaneously. Suppose
1302perl5.004_04 were to install /usr/lib/libperl.so.4.4, and perl5.004_05
1303were to install /usr/lib/libperl.so.4.5. Now, when you try to run
1304perl5.004_04, ld.so might try to load libperl.so.4.5, since it has
1305the right "major version" number. If this works at all, it almost
1306certainly defeats the reason for keeping perl5.004_04 around. Worse,
1307with development subversions, you certaily can't guarantee that
1308libperl.so.4.4 and libperl.so.4.55 will be compatible.
1309
1310Anyway, all this leads to quite obscure failures that are sure to drive
1311casual users crazy. Even experienced users will get confused :-). Upon
1312reflection, I'd say leave libperl.so in $archlib.
1313
94655993
SR
1314=back
1315
1316=head2 Indentation style
2032ff04 1317
94655993 1318Over the years Perl has become a mishmash of
2032ff04
JH
1319various indentation styles, but the original "Larry style" can
1320probably be restored with (GNU) indent somewhat like this:
1321
1322 indent -kr -nce -psl -sc
1323
55c0ed8c
JH
1324A more ambitious solution would also specify a list of Perl specific
1325types with -TSV -TAV -THV .. -TMAGIC -TPerlIO ... but that list would
1326be quite ungainly. Also note that GNU indent also doesn't do aligning
1327of consecutive assignments, which would truly wreck the layout in
1328places like sv.c:Perl_sv_upgrade() or sv.c:Perl_clone_using().
1329Similarly nicely aligned &&s, ||s and ==s would not be respected.
2032ff04 1330
aa689395
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1331=head1 Upload Your Work to CPAN
1332
1333You can upload your work to CPAN if you have a CPAN id. Check out
a93751fa 1334http://www.cpan.org/modules/04pause.html for information on
aa689395
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1335_PAUSE_, the Perl Author's Upload Server.
1336
1337I typically upload both the patch file, e.g. F<perl5.004_08.pat.gz>
1338and the full tar file, e.g. F<perl5.004_08.tar.gz>.
1339
1340If you want your patch to appear in the F<src/5.0/unsupported>
1341directory on CPAN, send e-mail to the CPAN master librarian. (Check
a93751fa 1342out http://www.cpan.org/CPAN.html ).
aa689395
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1343
1344=head1 Help Save the World
1345
1346You should definitely announce your patch on the perl5-porters list.
1347You should also consider announcing your patch on
1348comp.lang.perl.announce, though you should make it quite clear that a
1349subversion is not a production release, and be prepared to deal with
1350people who will not read your disclaimer.
1351
1352=head1 Todo
1353
1354Here, in no particular order, are some Configure and build-related
1355items that merit consideration. This list isn't exhaustive, it's just
1356what I came up with off the top of my head.
1357
e25f343d
PG
1358=head2 Adding missing library functions to Perl
1359
1360The perl Configure script automatically determines which headers and
1361functions you have available on your system and arranges for them to be
1362included in the compilation and linking process. Occasionally, when porting
1363perl to an operating system for the first time, you may find that the
1364operating system is missing a key function. While perl may still build
1365without this function, no perl program will be able to reference the missing
1366function. You may be able to write the missing function yourself, or you
1367may be able to find the missing function in the distribution files for
1368another software package. In this case, you need to instruct the perl
1369configure-and-build process to use your function. Perform these steps.
1370
1371=over 3
1372
1373=item *
1374
2ecb232b 1375Code and test the function you wish to add. Test it carefully; you will
e25f343d
PG
1376have a much easier time debugging your code independently than when it is a
1377part of perl.
1378
1379=item *
1380
1381Here is an implementation of the POSIX truncate function for an operating
1382system (VOS) that does not supply one, but which does supply the ftruncate()
1383function.
1384
1385 /* Beginning of modification history */
1386 /* Written 02-01-02 by Nick Ing-Simmons (nick@ing-simmons.net) */
1387 /* End of modification history */
1388
1389 /* VOS doesn't supply a truncate function, so we build one up
1390 from the available POSIX functions. */
1391
1392 #include <fcntl.h>
1393 #include <sys/types.h>
1394 #include <unistd.h>
1395
1396 int
1397 truncate(const char *path, off_t len)
1398 {
1399 int fd = open(path,O_WRONLY);
1400 int code = -1;
1401 if (fd >= 0) {
1402 code = ftruncate(fd,len);
1403 close(fd);
1404 }
1405 return code;
1406 }
1407
1408Place this file into a subdirectory that has the same name as the operating
1409system. This file is named perl/vos/vos.c
1410
1411=item *
1412
1413If your operating system has a hints file (in perl/hints/XXX.sh for an
1414operating system named XXX), then start with it. If your operating system
1415has no hints file, then create one. You can use a hints file for a similar
1416operating system, if one exists, as a template.
1417
1418=item *
1419
1420Add lines like the following to your hints file. The first line
1421(d_truncate="define") instructs Configure that the truncate() function
1422exists. The second line (archobjs="vos.o") instructs the makefiles that the
1423perl executable depends on the existence of a file named "vos.o". (Make
1424will automatically look for "vos.c" and compile it with the same options as
1425the perl source code). The final line ("test -h...") adds a symbolic link
1426to the top-level directory so that make can find vos.c. Of course, you
1427should use your own operating system name for the source file of extensions,
1428not "vos.c".
1429
1430 # VOS does not have truncate() but we supply one in vos.c
1431 d_truncate="define"
1432 archobjs="vos.o"
1433
1434 # Help gmake find vos.c
1435 test -h vos.c || ln -s vos/vos.c vos.c
1436
1437The hints file is a series of shell commands that are run in the top-level
1438directory (the "perl" directory). Thus, these commands are simply executed
1439by Configure at an appropriate place during its execution.
1440
1441=item *
1442
1443At this point, you can run the Configure script and rebuild perl. Carefully
1444test the newly-built perl to ensure that normal paths, and error paths,
1445behave as you expect.
1446
1447=back
1448
aa689395
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1449=head2 Good ideas waiting for round tuits
1450
1451=over 4
1452
c4f23d77 1453=item Configure -Dsrc=/blah/blah
aa689395
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1454
1455We should be able to emulate B<configure --srcdir>. Tom Tromey
1456tromey@creche.cygnus.com has submitted some patches to
c4f23d77
AD
1457the dist-users mailing list along these lines. They have been folded
1458back into the main distribution, but various parts of the perl
1459Configure/build/install process still assume src='.'.
aa689395
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1460
1461=item Hint file fixes
1462
1463Various hint files work around Configure problems. We ought to fix
1464Configure so that most of them aren't needed.
1465
1466=item Hint file information
1467
1468Some of the hint file information (particularly dynamic loading stuff)
1469ought to be fed back into the main metaconfig distribution.
1470
1471=back
1472
1473=head2 Probably good ideas waiting for round tuits
1474
1475=over 4
1476
1477=item GNU configure --options
1478
1479I've received sensible suggestions for --exec_prefix and other
1480GNU configure --options. It's not always obvious exactly what is
1481intended, but this merits investigation.
1482
1483=item make clean
1484
1485Currently, B<make clean> isn't all that useful, though
1486B<make realclean> and B<make distclean> are. This needs a bit of
1487thought and documentation before it gets cleaned up.
1488
1489=item Try gcc if cc fails
1490
1491Currently, we just give up.
1492
1493=item bypassing safe*alloc wrappers
1494
1495On some systems, it may be safe to call the system malloc directly
1496without going through the util.c safe* layers. (Such systems would
1497accept free(0), for example.) This might be a time-saver for systems
1498that already have a good malloc. (Recent Linux libc's apparently have
1499a nice malloc that is well-tuned for the system.)
1500
1501=back
1502
1503=head2 Vague possibilities
1504
1505=over 4
1506
aa689395
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1507=item MacPerl
1508
3e3baf6d 1509Get some of the Macintosh stuff folded back into the main distribution.
aa689395
PP
1510
1511=item gconvert replacement
1512
1513Maybe include a replacement function that doesn't lose data in rare
1514cases of coercion between string and numerical values.
1515
aa689395
PP
1516=item Improve makedepend
1517
1518The current makedepend process is clunky and annoyingly slow, but it
1519works for most folks. Alas, it assumes that there is a filename
1520$firstmakefile that the B<make> command will try to use before it uses
1521F<Makefile>. Such may not be the case for all B<make> commands,
1522particularly those on non-Unix systems.
1523
1524Probably some variant of the BSD F<.depend> file will be useful.
1525We ought to check how other packages do this, if they do it at all.
1526We could probably pre-generate the dependencies (with the exception of
1527malloc.o, which could probably be determined at F<Makefile.SH>
1528extraction time.
1529
1530=item GNU Makefile standard targets
1531
1532GNU software generally has standardized Makefile targets. Unless we
1533have good reason to do otherwise, I see no reason not to support them.
1534
1535=item File locking
1536
1537Somehow, straighten out, document, and implement lockf(), flock(),
76ba0908
PK
1538and/or fcntl() file locking. It's a mess. See $d_fcntl_can_lock
1539in recent config.sh files though.
aa689395
PP
1540
1541=back
1542
4bb101f2
JH
1543=head2 Copyright Issues
1544
1545The following is based on the consensus of a couple of IPR lawyers,
1546but it is of course not a legally binding statement, just a common
1547sense summary.
1548
1549=over 4
1550
1551=item *
1552
1553Tacking on copyright statements is unnecessary to begin with because
1554of the Berne convention. But assuming you want to go ahead...
1555
1556=item *
1557
1558The right form of a copyright statement is
1559
1560 Copyright (C) Year, Year, ... by Someone
1561
1562The (C) is not required everywhere but it doesn't hurt and in certain
1563jurisdictions it is required, so let's leave it in. (Yes, it's true
1564that in some jurisdictions the "(C)" is not legally binding, one should
1565use the true ringed-C. But we don't have that character available for
1566Perl's source code.)
1567
1568The years must be listed out separately. Year-Year is not correct.
1569Only the years when the piece has changed 'significantly' may be added.
1570
1571=item *
1572
1573One cannot give away one's copyright trivially. One can give one's
1574copyright away by using public domain, but even that requires a little
1575bit more than just saying 'this is in public domain'. (What it
1576exactly requires depends on your jurisdiction.) But barring public
1577domain, one cannot "transfer" one's copyright to another person or
1578entity. In the context of software, it means that contributors cannot
1579give away their copyright or "transfer" it to the "owner" of the software.
1580
1581Also remember that in many cases if you are employed by someone,
1582your work may be copyrighted to your employer, even when you are
1583contributing on your own time (this all depends on too many things
1584to list here). But the bottom line is that you definitely can't give
1585away a copyright you may not even have.
1586
1587What is possible, however, is that the software can simply state
1588
1589 Copyright (C) Year, Year, ... by Someone and others
1590
1591and then list the "others" somewhere in the distribution.
1592And this is exactly what Perl does. (The "somewhere" is
1593AUTHORS and the Changes* files.)
1594
1595=item *
1596
1597Split files, merged files, and generated files are problematic.
1598The rule of thumb: in split files, copy the copyright years of
1599the original file to all the new files; in merged files make
1600an union of the copyright years of all the old files; in generated
1601files propagate the copyright years of the generating file(s).
1602
1603=item *
1604
1605The files of Perl source code distribution do carry a lot of
1606copyrights, by various people. (There are many copyrights embedded in
1607perl.c, for example.) The most straightforward thing for pumpkings to
1608do is to simply update Larry's copyrights at the beginning of the
1609*.[hcy], x2p/*.[hcy], *.pl, and README files, and leave all other
1610copyrights alone. Doing more than that requires quite a bit of tracking.
1611
1612=back
1613
fb73857a 1614=head1 AUTHORS
aa689395 1615
36816da2 1616Original author: Andy Dougherty doughera@lafayette.edu .
fb73857a
PP
1617Additions by Chip Salzenberg chip@perl.com and
1618Tim Bunce Tim.Bunce@ig.co.uk .
aa689395
PP
1619
1620All opinions expressed herein are those of the authorZ<>(s).
1621
1622=head1 LAST MODIFIED
1623
ff935051 1624$Id: pumpkin.pod,v 1.23 2000/01/13 19:45:13 doughera Released $