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aa689395 | 1 | =head1 NAME |
2 | ||
e25f343d | 3 | Pumpkin - Notes on handling the Perl Patch Pumpkin And Porting Perl |
aa689395 | 4 | |
5 | =head1 SYNOPSIS | |
6 | ||
7 | There is no simple synopsis, yet. | |
8 | ||
9 | =head1 DESCRIPTION | |
10 | ||
98dddfbd JH |
11 | This document attempts to begin to describe some of the considerations |
12 | involved in patching, porting, and maintaining perl. | |
aa689395 | 13 | |
14 | This document is still under construction, and still subject to | |
15 | significant changes. Still, I hope parts of it will be useful, | |
16 | so I'm releasing it even though it's not done. | |
17 | ||
18 | For the most part, it's a collection of anecdotal information that | |
19 | already assumes some familiarity with the Perl sources. I really need | |
20 | an introductory section that describes the organization of the sources | |
21 | and all the various auxiliary files that are part of the distribution. | |
22 | ||
23 | =head1 Where Do I Get Perl Sources and Related Material? | |
24 | ||
25 | The Comprehensive Perl Archive Network (or CPAN) is the place to go. | |
26 | There are many mirrors, but the easiest thing to use is probably | |
a93751fa | 27 | http://www.cpan.org/README.html , which automatically points you to a |
aa689395 | 28 | mirror site "close" to you. |
29 | ||
30 | =head2 Perl5-porters mailing list | |
31 | ||
32 | The mailing list perl5-porters@perl.org | |
33 | is the main group working with the development of perl. If you're | |
34 | interested in all the latest developments, you should definitely | |
35 | subscribe. The list is high volume, but generally has a | |
36 | fairly low noise level. | |
37 | ||
38 | Subscribe by sending the message (in the body of your letter) | |
39 | ||
40 | subscribe perl5-porters | |
41 | ||
42 | to perl5-porters-request@perl.org . | |
43 | ||
fb73857a | 44 | Archives of the list are held at: |
45 | ||
46 | http://www.rosat.mpe-garching.mpg.de/mailing-lists/perl-porters/ | |
47 | ||
aa689395 | 48 | =head1 How are Perl Releases Numbered? |
49 | ||
f5a32c7f GS |
50 | Beginning with v5.6.0, even versions will stand for maintenance releases |
51 | and odd versions for development releases, i.e., v5.6.x for maintenance | |
52 | releases, and v5.7.x for development releases. Before v5.6.0, subversions | |
53 | _01 through _49 were reserved for bug-fix maintenance releases, and | |
54 | subversions _50 through _99 for unstable development versions. | |
7b5757d1 | 55 | |
f5a32c7f GS |
56 | For example, in v5.6.1, the revision number is 5, the version is 6, |
57 | and 1 is the subversion. | |
aa689395 | 58 | |
f5a32c7f GS |
59 | For compatibility with the older numbering scheme the composite floating |
60 | point version number continues to be available as the magic variable $], | |
76ba0908 | 61 | and amounts to C<$revision + $version/1000 + $subversion/100000>. This |
f5a32c7f | 62 | can still be used in comparisons. |
aa689395 | 63 | |
f5a32c7f | 64 | print "You've got an old perl\n" if $] < 5.005_03; |
aa689395 | 65 | |
f5a32c7f | 66 | In 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 | 70 | You can also require particular version (or later) with: |
aa689395 | 71 | |
f5a32c7f | 72 | use 5.006; |
aa689395 | 73 | |
f5a32c7f | 74 | or using the new syntax available only from v5.6 onward: |
aa689395 | 75 | |
f5a32c7f | 76 | use v5.6.0; |
aa689395 | 77 | |
f5a32c7f GS |
78 | At some point in the future, we may need to decide what to call the |
79 | next big revision. In the .package file used by metaconfig to | |
80 | generate Configure, there are two variables that might be relevant: | |
81 | $baserev=5 and $package=perl5. | |
aa689395 | 82 | |
f5a32c7f | 83 | Perl releases produced by the members of perl5-porters are usually |
e04b929a GS |
84 | available on CPAN in the F<src/5.0/maint> and F<src/5.0/devel> |
85 | directories. | |
aa689395 | 86 | |
7b5757d1 AD |
87 | =head2 Maintenance and Development Subversions |
88 | ||
f5a32c7f | 89 | The first rule of maintenance work is "First, do no harm." |
7b5757d1 | 90 | |
fb73857a | 91 | Trial releases of bug-fix maintenance releases are announced on |
92 | perl5-porters. Trial releases use the new subversion number (to avoid | |
93 | testers installing it over the previous release) and include a 'local | |
e04b929a GS |
94 | patch' entry in patchlevel.h. The distribution file contains the |
95 | string C<MAINT_TRIAL> to make clear that the file is not meant for | |
96 | public consumption. | |
fb73857a | 97 | |
e04b929a | 98 | In general, the names of official distribution files for the public |
f5a32c7f | 99 | always match the regular expression: |
e04b929a | 100 | |
f5a32c7f | 101 | ^perl\d+\.(\d+)\.\d+(-MAINT_TRIAL_\d+)\.tar\.gz$ |
e04b929a | 102 | |
f5a32c7f GS |
103 | C<$1> in the pattern is always an even number for maintenance |
104 | versions, and odd for developer releases. | |
e04b929a GS |
105 | |
106 | In the past it has been observed that pumkings tend to invent new | |
107 | naming conventions on the fly. If you are a pumpking, before you | |
108 | invent a new name for any of the three types of perl distributions, | |
109 | please inform the guys from the CPAN who are doing indexing and | |
110 | provide the trees of symlinks and the like. They will have to know | |
111 | I<in advance> what you decide. | |
20f245af | 112 | |
aa689395 | 113 | =head2 Why is it called the patch pumpkin? |
114 | ||
115 | Chip Salzenberg gets credit for that, with a nod to his cow orker, | |
116 | David Croy. We had passed around various names (baton, token, hot | |
117 | potato) but none caught on. Then, Chip asked: | |
118 | ||
119 | [begin quote] | |
120 | ||
121 | Who has the patch pumpkin? | |
122 | ||
123 | To explain: David Croy once told me once that at a previous job, | |
124 | there was one tape drive and multiple systems that used it for backups. | |
125 | But instead of some high-tech exclusion software, they used a low-tech | |
126 | method to prevent multiple simultaneous backups: a stuffed pumpkin. | |
127 | No one was allowed to make backups unless they had the "backup pumpkin". | |
128 | ||
129 | [end quote] | |
130 | ||
131 | The name has stuck. | |
132 | ||
a6968aa6 | 133 | =head1 Philosophical Issues in Patching and Porting Perl |
aa689395 | 134 | |
135 | There are no absolute rules, but there are some general guidelines I | |
136 | have 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 | ||
7b5757d1 AD |
141 | Never implement a specific restricted solution to a problem when you |
142 | can solve the same problem in a more general, flexible way. | |
143 | ||
144 | For example, for dynamic loading to work on some SVR4 systems, we had | |
145 | to build a shared libperl.so library. In order to build "FAT" binaries | |
146 | on NeXT 4.0 systems, we had to build a special libperl library. Rather | |
147 | than continuing to build a contorted nest of special cases, I | |
148 | generalized the process of building libperl so that NeXT and SVR4 users | |
149 | could still get their work done, but others could build a shared | |
150 | libperl if they wanted to as well. | |
aa689395 | 151 | |
a6968aa6 JH |
152 | Contain your changes carefully. Assume nothing about other operating |
153 | systems, not even closely related ones. Your changes must not affect | |
154 | other platforms. | |
155 | ||
156 | Spy shamelessly on how similar patching or porting issues have been | |
157 | settled elsewhere. | |
158 | ||
159 | If feasible, try to keep filenames 8.3-compliant to humor those poor | |
160 | souls that get joy from running Perl under such dire limitations. | |
9e371ce5 | 161 | There's a script, check83.pl, for keeping your nose 8.3-clean. |
a6968aa6 | 162 | |
aa689395 | 163 | =head2 Seek consensus on major changes |
164 | ||
165 | If you are making big changes, don't do it in secret. Discuss the | |
166 | ideas in advance on perl5-porters. | |
167 | ||
168 | =head2 Keep the documentation up-to-date | |
169 | ||
170 | If your changes may affect how users use perl, then check to be sure | |
171 | that the documentation is in sync with your changes. Be sure to | |
172 | check all the files F<pod/*.pod> and also the F<INSTALL> document. | |
173 | ||
174 | Consider writing the appropriate documentation first and then | |
7b5757d1 | 175 | implementing your change to correspond to the documentation. |
aa689395 | 176 | |
177 | =head2 Avoid machine-specific #ifdef's | |
178 | ||
179 | To the extent reasonable, try to avoid machine-specific #ifdef's in | |
180 | the sources. Instead, use feature-specific #ifdef's. The reason is | |
181 | that the machine-specific #ifdef's may not be valid across major | |
182 | releases of the operating system. Further, the feature-specific tests | |
183 | may help out folks on another platform who have the same problem. | |
184 | ||
a6968aa6 JH |
185 | =head2 Machine-specific files |
186 | ||
98dddfbd JH |
187 | =over 4 |
188 | ||
189 | =item source code | |
190 | ||
a6968aa6 JH |
191 | If you have many machine-specific #defines or #includes, consider |
192 | creating an "osish.h" (os2ish.h, vmsish.h, and so on) and including | |
193 | that in perl.h. If you have several machine-specific files (function | |
194 | emulations, function stubs, build utility wrappers) you may create a | |
195 | separate subdirectory (djgpp, win32) and put the files in there. | |
98dddfbd | 196 | Remember to update C<MANIFEST> when you add files. |
a6968aa6 | 197 | |
ff935051 | 198 | If your system supports dynamic loading but none of the existing |
98dddfbd JH |
199 | methods at F<ext/DynaLoader/dl_*.xs> work for you, you must write |
200 | a new one. Study the existing ones to see what kind of interface | |
201 | you must supply. | |
202 | ||
203 | =item build hints | |
a6968aa6 JH |
204 | |
205 | There are two kinds of hints: hints for building Perl and hints for | |
206 | extensions. The former live in the C<hints> subdirectory, the latter | |
207 | in C<ext/*/hints> subdirectories. | |
208 | ||
209 | The top level hints are Bourne-shell scripts that set, modify and | |
210 | unset appropriate Configure variables, based on the Configure command | |
211 | line options and possibly existing config.sh and Policy.sh files from | |
212 | previous Configure runs. | |
213 | ||
76ba0908 | 214 | The extension hints are written in Perl (by the time they are used |
a6968aa6 JH |
215 | miniperl has been built) and control the building of their respective |
216 | extensions. They can be used to for example manipulate compilation | |
217 | and linking flags. | |
218 | ||
98dddfbd JH |
219 | =item build and installation Makefiles, scripts, and so forth |
220 | ||
221 | Sometimes you will also need to tweak the Perl build and installation | |
222 | procedure itself, like for example F<Makefile.SH> and F<installperl>. | |
223 | Tread very carefully, even more than usual. Contain your changes | |
224 | with utmost care. | |
a6968aa6 | 225 | |
98dddfbd JH |
226 | =item test suite |
227 | ||
228 | Many of the tests in C<t> subdirectory assume machine-specific things | |
a6968aa6 JH |
229 | like existence of certain functions, something about filesystem |
230 | semantics, certain external utilities and their error messages. Use | |
231 | the C<$^O> and the C<Config> module (which contains the results of the | |
232 | Configure run, in effect the C<config.sh> converted to Perl) to either | |
98dddfbd JH |
233 | skip (preferably not) or customize (preferable) the tests for your |
234 | platform. | |
235 | ||
236 | =item modules | |
237 | ||
238 | Certain standard modules may need updating if your operating system | |
239 | sports for example a native filesystem naming. You may want to update | |
240 | some or all of the modules File::Basename, File::Spec, File::Path, and | |
241 | File::Copy to become aware of your native filesystem syntax and | |
242 | peculiarities. | |
243 | ||
b972f109 JH |
244 | Remember to have a $VERSION in the modules. You can use the |
245 | Porting/checkVERSION.pl script for checking this. | |
246 | ||
98dddfbd JH |
247 | =item documentation |
248 | ||
249 | If your operating system comes from outside UNIX you almost certainly | |
250 | will have differences in the available operating system functionality | |
251 | (missing system calls, different semantics, whatever). Please | |
252 | document these at F<pod/perlport.pod>. If your operating system is | |
253 | the first B<not> to have a system call also update the list of | |
254 | "portability-bewares" at the beginning of F<pod/perlfunc.pod>. | |
255 | ||
256 | A file called F<README.youros> at the top level that explains things | |
257 | like how to install perl at this platform, where to get any possibly | |
258 | required additional software, and for example what test suite errors | |
76ba0908 PK |
259 | to expect, is nice too. Such files are in the process of being written |
260 | in pod format and will eventually be renamed F<INSTALL.youros>. | |
98dddfbd JH |
261 | |
262 | You may also want to write a separate F<.pod> file for your operating | |
263 | system to tell about existing mailing lists, os-specific modules, | |
264 | documentation, whatever. Please name these along the lines of | |
265 | F<perl>I<youros>.pod. [unfinished: where to put this file (the pod/ | |
266 | subdirectory, of course: but more importantly, which/what index files | |
267 | should be updated?)] | |
268 | ||
269 | =back | |
a6968aa6 | 270 | |
aa689395 | 271 | =head2 Allow for lots of testing |
272 | ||
273 | We should never release a main version without testing it as a | |
274 | subversion first. | |
275 | ||
6877a1cf AD |
276 | =head2 Test popular applications and modules. |
277 | ||
278 | We should never release a main version without testing whether or not | |
279 | it breaks various popular modules and applications. A partial list of | |
280 | such things would include majordomo, metaconfig, apache, Tk, CGI, | |
281 | libnet, and libwww, to name just a few. Of course it's quite possible | |
282 | that some of those things will be just plain broken and need to be fixed, | |
283 | but, in general, we ought to try to avoid breaking widely-installed | |
284 | things. | |
285 | ||
98dddfbd | 286 | =head2 Automated generation of derivative files |
aa689395 | 287 | |
288 | The F<embed.h>, F<keywords.h>, F<opcode.h>, and F<perltoc.pod> files | |
289 | are all automatically generated by perl scripts. In general, don't | |
290 | patch these directly; patch the data files instead. | |
291 | ||
292 | F<Configure> and F<config_h.SH> are also automatically generated by | |
293 | B<metaconfig>. In general, you should patch the metaconfig units | |
a6968aa6 JH |
294 | instead of patching these files directly. However, very minor changes |
295 | to F<Configure> may be made in between major sync-ups with the | |
296 | metaconfig units, which tends to be complicated operations. But be | |
297 | careful, this can quickly spiral out of control. Running metaconfig | |
298 | is not really hard. | |
aa689395 | 299 | |
98dddfbd JH |
300 | Also F<Makefile> is automatically produced from F<Makefile.SH>. |
301 | In general, look out for all F<*.SH> files. | |
302 | ||
a8119d38 AD |
303 | Finally, the sample files in the F<Porting/> subdirectory are |
304 | generated automatically by the script F<U/mksample> included | |
305 | with the metaconfig units. See L<"run metaconfig"> below for | |
306 | information on obtaining the metaconfig units. | |
307 | ||
aa689395 | 308 | =head1 How to Make a Distribution |
309 | ||
310 | There really ought to be a 'make dist' target, but there isn't. | |
311 | The 'dist' suite of tools also contains a number of tools that I haven't | |
312 | learned how to use yet. Some of them may make this all a bit easier. | |
313 | ||
314 | Here are the steps I go through to prepare a patch & distribution. | |
315 | ||
3e3baf6d TB |
316 | Lots of it could doubtless be automated but isn't. The Porting/makerel |
317 | (make release) perl script does now help automate some parts of it. | |
aa689395 | 318 | |
319 | =head2 Announce your intentions | |
320 | ||
321 | First, you should volunteer out loud to take the patch pumpkin. It's | |
322 | generally counter-productive to have multiple people working in secret | |
323 | on the same thing. | |
324 | ||
325 | At the same time, announce what you plan to do with the patch pumpkin, | |
326 | to allow folks a chance to object or suggest alternatives, or do it for | |
327 | you. Naturally, the patch pumpkin holder ought to incorporate various | |
328 | bug fixes and documentation improvements that are posted while he or | |
329 | she has the pumpkin, but there might also be larger issues at stake. | |
330 | ||
331 | One of the precepts of the subversion idea is that we shouldn't give | |
7b5757d1 AD |
332 | the patch pumpkin to anyone unless we have some idea what he or she |
333 | is going to do with it. | |
aa689395 | 334 | |
335 | =head2 refresh pod/perltoc.pod | |
336 | ||
337 | Presumably, you have done a full C<make> in your working source | |
338 | directory. Before you C<make spotless> (if you do), and if you have | |
339 | changed any documentation in any module or pod file, change to the | |
340 | F<pod> directory and run C<make toc>. | |
341 | ||
3e3baf6d TB |
342 | =head2 run installhtml to check the validity of the pod files |
343 | ||
aa689395 | 344 | =head2 update patchlevel.h |
345 | ||
346 | Don't be shy about using the subversion number, even for a relatively | |
347 | modest patch. We've never even come close to using all 99 subversions, | |
348 | and it's better to have a distinctive number for your patch. If you | |
349 | need feedback on your patch, go ahead and issue it and promise to | |
350 | incorporate that feedback quickly (e.g. within 1 week) and send out a | |
351 | second patch. | |
352 | ||
05ff1fbb RB |
353 | If you update the subversion number, you may need to change the version |
354 | number near the top of the F<Changes> file. | |
355 | ||
aa689395 | 356 | =head2 run metaconfig |
357 | ||
358 | If you need to make changes to Configure or config_h.SH, it may be best to | |
359 | change the appropriate metaconfig units instead, and regenerate Configure. | |
360 | ||
361 | metaconfig -m | |
362 | ||
20f245af AD |
363 | will regenerate Configure and config_h.SH. Much more information |
364 | on obtaining and running metaconfig is in the F<U/README> file | |
365 | that comes with Perl's metaconfig units. Perl's metaconfig units | |
366 | should be available on CPAN. A set of units that will work with | |
367 | perl5.005 is in the file F<mc_units-5.005_00-01.tar.gz> under | |
a93751fa | 368 | http://www.cpan.org/authors/id/ANDYD/ . The mc_units tar file |
20f245af AD |
369 | should be unpacked in your main perl source directory. Note: those |
370 | units were for use with 5.005. There may have been changes since then. | |
d562869c | 371 | Check for later versions or contact perl5-porters@perl.org to obtain a |
20f245af | 372 | pointer to the current version. |
aa689395 | 373 | |
374 | Alternatively, do consider if the F<*ish.h> files might be a better | |
375 | place for your changes. | |
376 | ||
377 | =head2 MANIFEST | |
378 | ||
379 | Make sure the MANIFEST is up-to-date. You can use dist's B<manicheck> | |
380 | program for this. You can also use | |
381 | ||
3e3baf6d | 382 | perl -w -MExtUtils::Manifest=fullcheck -e fullcheck |
aa689395 | 383 | |
3e3baf6d TB |
384 | Both commands will also list extra files in the directory that are not |
385 | listed in MANIFEST. | |
aa689395 | 386 | |
bfb7748a | 387 | The MANIFEST is normally sorted. |
aa689395 | 388 | |
389 | If you are using metaconfig to regenerate Configure, then you should note | |
390 | that metaconfig actually uses MANIFEST.new, so you want to be sure | |
391 | MANIFEST.new is up-to-date too. I haven't found the MANIFEST/MANIFEST.new | |
392 | distinction particularly useful, but that's probably because I still haven't | |
393 | learned how to use the full suite of tools in the dist distribution. | |
394 | ||
395 | =head2 Check permissions | |
396 | ||
397 | All the tests in the t/ directory ought to be executable. The | |
398 | main makefile used to do a 'chmod t/*/*.t', but that resulted in | |
399 | a self-modifying distribution--something some users would strongly | |
d562869c AD |
400 | prefer to avoid. The F<t/TEST> script will check for this |
401 | and do the chmod if needed, but the tests still ought to be | |
402 | executable. | |
aa689395 | 403 | |
404 | In all, the following files should probably be executable: | |
405 | ||
406 | Configure | |
407 | configpm | |
32fcaa0b | 408 | configure.gnu |
aa689395 | 409 | embed.pl |
410 | installperl | |
411 | installman | |
412 | keywords.pl | |
aa689395 | 413 | myconfig |
414 | opcode.pl | |
415 | perly.fixer | |
416 | t/TEST | |
417 | t/*/*.t | |
418 | *.SH | |
419 | vms/ext/Stdio/test.pl | |
420 | vms/ext/filespec.t | |
aa689395 | 421 | x2p/*.SH |
422 | ||
423 | Other things ought to be readable, at least :-). | |
424 | ||
425 | Probably, the permissions for the files could be encoded in MANIFEST | |
426 | somehow, but I'm reluctant to change MANIFEST itself because that | |
427 | could break old scripts that use MANIFEST. | |
428 | ||
429 | I seem to recall that some SVR3 systems kept some sort of file that listed | |
430 | permissions for system files; something like that might be appropriate. | |
431 | ||
432 | =head2 Run Configure | |
433 | ||
434 | This will build a config.sh and config.h. You can skip this if you haven't | |
693762b4 | 435 | changed Configure or config_h.SH at all. I use the following command |
aa689395 | 436 | |
693762b4 AD |
437 | sh Configure -Dprefix=/opt/perl -Doptimize=-O -Dusethreads \ |
438 | -Dcf_by='yourname' \ | |
439 | -Dcf_email='yourname@yourhost.yourplace.com' \ | |
440 | -Dperladmin='yourname@yourhost.yourplace.com' \ | |
441 | -Dmydomain='.yourplace.com' \ | |
442 | -Dmyhostname='yourhost' \ | |
443 | -des | |
aa689395 | 444 | |
693762b4 | 445 | =head2 Update Porting/config.sh and Porting/config_H |
dfe9444c | 446 | |
693762b4 AD |
447 | [XXX |
448 | This section needs revision. We're currently working on easing | |
449 | the task of keeping the vms, win32, and plan9 config.sh info | |
450 | up-to-date. The plan is to use keep up-to-date 'canned' config.sh | |
451 | files in the appropriate subdirectories and then generate 'canned' | |
452 | config.h files for vms, win32, etc. from the generic config.sh file. | |
453 | This is to ease maintenance. When Configure gets updated, the parts | |
454 | sometimes get scrambled around, and the changes in config_H can | |
455 | sometimes be very hard to follow. config.sh, on the other hand, can | |
456 | safely be sorted, so it's easy to track (typically very small) changes | |
457 | to config.sh and then propoagate them to a canned 'config.h' by any | |
458 | number of means, including a perl script in win32/ or carrying | |
459 | config.sh and config_h.SH to a Unix system and running sh | |
76ba0908 PK |
460 | config_h.SH.) Vms uses configure.com to generate its own config.sh |
461 | and config.h. If you want to add a new variable to config.sh check | |
462 | with vms folk how to add it to configure.com too. | |
693762b4 AD |
463 | XXX] |
464 | ||
465 | The Porting/config.sh and Porting/config_H files are provided to | |
466 | help those folks who can't run Configure. It is important to keep | |
467 | them up-to-date. If you have changed config_h.SH, those changes must | |
468 | be reflected in config_H as well. (The name config_H was chosen to | |
469 | distinguish the file from config.h even on case-insensitive file systems.) | |
470 | Simply edit the existing config_H file; keep the first few explanatory | |
471 | lines and then copy your new config.h below. | |
aa689395 | 472 | |
76ba0908 | 473 | It may also be necessary to update win32/config.?c, and |
aa689395 | 474 | plan9/config.plan9, though you should be quite careful in doing so if |
475 | you are not familiar with those systems. You might want to issue your | |
476 | patch with a promise to quickly issue a follow-up that handles those | |
477 | directories. | |
478 | ||
479 | =head2 make run_byacc | |
480 | ||
481 | If you have byacc-1.8.2 (available from CPAN), and if there have been | |
482 | changes to F<perly.y>, you can regenerate the F<perly.c> file. The | |
483 | run_byacc makefile target does this by running byacc and then applying | |
484 | some patches so that byacc dynamically allocates space, rather than | |
485 | having fixed limits. This patch is handled by the F<perly.fixer> | |
486 | script. Depending on the nature of the changes to F<perly.y>, you may | |
487 | or may not have to hand-edit the patch to apply correctly. If you do, | |
488 | you should include the edited patch in the new distribution. If you | |
489 | have byacc-1.9, the patch won't apply cleanly. Changes to the printf | |
490 | output statements mean the patch won't apply cleanly. Long ago I | |
491 | started to fix F<perly.fixer> to detect this, but I never completed the | |
492 | task. | |
493 | ||
76ba0908 PK |
494 | If C<perly.c> or C<perly.h> changes, make sure you run C<perl vms/vms_yfix.pl> |
495 | to update the corresponding VMS files. This could be taken care of by | |
496 | the regen_all target in the Unix Makefile. See also | |
497 | L<VMS-specific updates>. | |
ebb99254 | 498 | |
aa689395 | 499 | Some additional notes from Larry on this: |
500 | ||
e262e9be | 501 | Don't forget to regenerate perly_c.diff. |
aa689395 | 502 | |
7b5757d1 | 503 | byacc -d perly.y |
aa689395 | 504 | mv y.tab.c perly.c |
e262e9be | 505 | patch perly.c <perly_c.diff |
aa689395 | 506 | # manually apply any failed hunks |
eade9b71 | 507 | diff -c perly.c.orig perly.c >perly_c.diff |
aa689395 | 508 | |
509 | One chunk of lines that often fails begins with | |
510 | ||
511 | #line 29 "perly.y" | |
512 | ||
513 | and ends one line before | |
514 | ||
515 | #define YYERRCODE 256 | |
516 | ||
517 | This only happens when you add or remove a token type. I suppose this | |
518 | could be automated, but it doesn't happen very often nowadays. | |
519 | ||
520 | Larry | |
521 | ||
76ba0908 PK |
522 | =head2 make regen_all |
523 | ||
524 | This target takes care of the PERLYVMS, regen_headers, and regen_pods | |
525 | targets. | |
526 | ||
aa689395 | 527 | =head2 make regen_headers |
528 | ||
529 | The F<embed.h>, F<keywords.h>, and F<opcode.h> files are all automatically | |
530 | generated by perl scripts. Since the user isn't guaranteed to have a | |
531 | working perl, we can't require the user to generate them. Hence you have | |
532 | to, if you're making a distribution. | |
533 | ||
534 | I used to include rules like the following in the makefile: | |
535 | ||
536 | # The following three header files are generated automatically | |
537 | # The correct versions should be already supplied with the perl kit, | |
538 | # in case you don't have perl or 'sh' available. | |
539 | # The - is to ignore error return codes in case you have the source | |
540 | # installed read-only or you don't have perl yet. | |
541 | keywords.h: keywords.pl | |
542 | @echo "Don't worry if this fails." | |
543 | - perl keywords.pl | |
544 | ||
545 | ||
7b5757d1 | 546 | However, I got B<lots> of mail consisting of people worrying because the |
aa689395 | 547 | command failed. I eventually decided that I would save myself time |
548 | and effort by manually running C<make regen_headers> myself rather | |
549 | than answering all the questions and complaints about the failing | |
550 | command. | |
551 | ||
76ba0908 PK |
552 | =head2 make regen_pods |
553 | ||
554 | Will run `make regen_pods` in the pod directory for indexing. | |
555 | ||
3e3baf6d | 556 | =head2 global.sym, interp.sym and perlio.sym |
aa689395 | 557 | |
558 | Make sure these files are up-to-date. Read the comments in these | |
559 | files and in perl_exp.SH to see what to do. | |
560 | ||
561 | =head2 Binary compatibility | |
562 | ||
563 | If you do change F<global.sym> or F<interp.sym>, think carefully about | |
564 | what you are doing. To the extent reasonable, we'd like to maintain | |
76ba0908 | 565 | source and binary compatibility with older releases of perl. That way, |
aa689395 | 566 | extensions built under one version of perl will continue to work with |
567 | new versions of perl. | |
568 | ||
569 | Of course, some incompatible changes may well be necessary. I'm just | |
570 | suggesting that we not make any such changes without thinking carefully | |
571 | about them first. If possible, we should provide | |
572 | backwards-compatibility stubs. There's a lot of XS code out there. | |
573 | Let's not force people to keep changing it. | |
574 | ||
575 | =head2 Changes | |
576 | ||
577 | Be sure to update the F<Changes> file. Try to include both an overall | |
578 | summary as well as detailed descriptions of the changes. Your | |
3e3baf6d | 579 | audience will include other developers and users, so describe |
aa689395 | 580 | user-visible changes (if any) in terms they will understand, not in |
581 | code like "initialize foo variable in bar function". | |
582 | ||
583 | There are differing opinions on whether the detailed descriptions | |
584 | ought to go in the Changes file or whether they ought to be available | |
585 | separately in the patch file (or both). There is no disagreement that | |
586 | detailed descriptions ought to be easily available somewhere. | |
587 | ||
05ff1fbb RB |
588 | If you update the subversion number in F<patchlevel.h>, you may need |
589 | to change the version number near the top of the F<Changes> file. | |
590 | ||
2a26e2f1 DD |
591 | =head2 Todo |
592 | ||
593 | The F<Todo> file contains a roughly-catgorized unordered list of | |
594 | aspects of Perl that could use enhancement, features that could be | |
595 | added, areas that could be cleaned up, and so on. During your term as | |
596 | pumpkin-holder, you will probably address some of these issues, and | |
597 | perhaps identify others which, while you decide not to address them | |
598 | this time around, may be tackled in the future. Update the file | |
599 | reflect the situation as it stands when you hand over the pumpkin. | |
600 | ||
601 | You might like, early in your pumpkin-holding career, to see if you | |
602 | can find champions for partiticular issues on the to-do list: an issue | |
603 | owned is an issue more likely to be resolved. | |
604 | ||
c4f23d77 AD |
605 | There are also some more porting-specific L<Todo> items later in this |
606 | file. | |
607 | ||
aa689395 | 608 | =head2 OS/2-specific updates |
609 | ||
610 | In the os2 directory is F<diff.configure>, a set of OS/2-specific | |
611 | diffs against B<Configure>. If you make changes to Configure, you may | |
612 | want to consider regenerating this diff file to save trouble for the | |
613 | OS/2 maintainer. | |
614 | ||
7b5757d1 AD |
615 | You can also consider the OS/2 diffs as reminders of portability |
616 | things that need to be fixed in Configure. | |
617 | ||
aa689395 | 618 | =head2 VMS-specific updates |
619 | ||
ebb99254 | 620 | If you have changed F<perly.y> or F<perly.c>, then you most probably want |
76ba0908 PK |
621 | to update F<vms/perly_{h,c}.vms> by running C<perl vms/vms_yfix.pl>, or |
622 | by running `make regen_all` which will run that script for you. | |
aa689395 | 623 | |
76ba0908 PK |
624 | The Perl revision number appears as "perl5" in configure.com. |
625 | It is courteous to update that if necessary. | |
aa689395 | 626 | |
627 | =head2 Making the new distribution | |
628 | ||
629 | Suppose, for example, that you want to make version 5.004_08. Then you can | |
630 | do something like the following | |
631 | ||
632 | mkdir ../perl5.004_08 | |
633 | awk '{print $1}' MANIFEST | cpio -pdm ../perl5.004_08 | |
634 | cd ../ | |
635 | tar cf perl5.004_08.tar perl5.004_08 | |
636 | gzip --best perl5.004_08.tar | |
637 | ||
3e3baf6d TB |
638 | These steps, with extra checks, are automated by the Porting/makerel |
639 | script. | |
640 | ||
aa689395 | 641 | =head2 Making a new patch |
642 | ||
643 | I find the F<makepatch> utility quite handy for making patches. | |
644 | You can obtain it from any CPAN archive under | |
a93751fa | 645 | http://www.cpan.org/authors/Johan_Vromans/ . There are a couple |
3e3baf6d TB |
646 | of differences between my version and the standard one. I have mine do |
647 | a | |
aa689395 | 648 | |
649 | # Print a reassuring "End of Patch" note so people won't | |
650 | # wonder if their mailer truncated patches. | |
651 | print "\n\nEnd of Patch.\n"; | |
652 | ||
3e3baf6d TB |
653 | at the end. That's because I used to get questions from people asking |
654 | if their mail was truncated. | |
655 | ||
656 | It also writes Index: lines which include the new directory prefix | |
657 | (change Index: print, approx line 294 or 310 depending on the version, | |
658 | to read: print PATCH ("Index: $newdir$new\n");). That helps patches | |
659 | work with more POSIX conformant patch programs. | |
aa689395 | 660 | |
661 | Here's how I generate a new patch. I'll use the hypothetical | |
662 | 5.004_07 to 5.004_08 patch as an example. | |
663 | ||
664 | # unpack perl5.004_07/ | |
665 | gzip -d -c perl5.004_07.tar.gz | tar -xof - | |
666 | # unpack perl5.004_08/ | |
667 | gzip -d -c perl5.004_08.tar.gz | tar -xof - | |
668 | makepatch perl5.004_07 perl5.004_08 > perl5.004_08.pat | |
669 | ||
670 | Makepatch will automatically generate appropriate B<rm> commands to remove | |
671 | deleted files. Unfortunately, it will not correctly set permissions | |
672 | for newly created files, so you may have to do so manually. For example, | |
673 | patch 5.003_04 created a new test F<t/op/gv.t> which needs to be executable, | |
674 | so at the top of the patch, I inserted the following lines: | |
675 | ||
676 | # Make a new test | |
677 | touch t/op/gv.t | |
678 | chmod +x t/opt/gv.t | |
679 | ||
680 | Now, of course, my patch is now wrong because makepatch didn't know I | |
681 | was going to do that command, and it patched against /dev/null. | |
682 | ||
683 | So, what I do is sort out all such shell commands that need to be in the | |
684 | patch (including possible mv-ing of files, if needed) and put that in the | |
685 | shell commands at the top of the patch. Next, I delete all the patch parts | |
686 | of perl5.004_08.pat, leaving just the shell commands. Then, I do the | |
687 | following: | |
688 | ||
7b5757d1 AD |
689 | cd perl5.004_07 |
690 | sh ../perl5.004_08.pat | |
aa689395 | 691 | cd .. |
7b5757d1 | 692 | makepatch perl5.004_07 perl5.004_08 >> perl5.004_08.pat |
aa689395 | 693 | |
694 | (Note the append to preserve my shell commands.) | |
695 | Now, my patch will line up with what the end users are going to do. | |
696 | ||
697 | =head2 Testing your patch | |
698 | ||
699 | It seems obvious, but be sure to test your patch. That is, verify that | |
700 | it produces exactly the same thing as your full distribution. | |
701 | ||
7b5757d1 AD |
702 | rm -rf perl5.004_07 |
703 | gzip -d -c perl5.004_07.tar.gz | tar -xf - | |
704 | cd perl5.004_07 | |
705 | sh ../perl5.004_08.pat | |
706 | patch -p1 -N < ../perl5.004_08.pat | |
aa689395 | 707 | cd .. |
7b5757d1 | 708 | gdiff -r perl5.004_07 perl5.004_08 |
aa689395 | 709 | |
710 | where B<gdiff> is GNU diff. Other diff's may also do recursive checking. | |
711 | ||
712 | =head2 More testing | |
713 | ||
714 | Again, it's obvious, but you should test your new version as widely as you | |
715 | can. You can be sure you'll hear about it quickly if your version doesn't | |
716 | work on both ANSI and pre-ANSI compilers, and on common systems such as | |
717 | SunOS 4.1.[34], Solaris, and Linux. | |
718 | ||
719 | If your changes include conditional code, try to test the different | |
720 | branches as thoroughly as you can. For example, if your system | |
721 | supports dynamic loading, you can also test static loading with | |
722 | ||
723 | sh Configure -Uusedl | |
724 | ||
725 | You can also hand-tweak your config.h to try out different #ifdef | |
726 | branches. | |
727 | ||
d2560b70 RB |
728 | =head2 Other tests |
729 | ||
730 | =over 4 | |
731 | ||
732 | =item CHECK_FORMAT | |
733 | ||
734 | To test the correct use of printf-style arguments, C<Configure> with | |
735 | S<-Dccflags='-DCHECK_FORMAT -Wformat'> and run C<make>. The compiler | |
736 | will produce warning of incorrect use of format arguments. CHECK_FORMAT | |
737 | changes perl-defined formats to common formats, so DO NOT USE the executable | |
738 | produced by this process. | |
739 | ||
740 | A more accurate approach is the following commands: | |
741 | ||
b3fe4827 RB |
742 | =over 4 |
743 | ||
744 | =item * | |
745 | ||
746 | build miniperl with -DCHECK_FORMAT | |
747 | ||
748 | make clean | |
749 | make miniperl OPTIMIZE=-DCHECK_FORMAT >& mini.log | |
750 | ||
751 | =item * | |
752 | ||
753 | build a clean miniperl, | |
754 | and build everything else from that with -DCHECK_FORMAT | |
755 | ||
d2560b70 | 756 | make clean |
b3fe4827 | 757 | make miniperl |
436c6dd3 | 758 | make all OPTIMIZE='-DCHECK_FORMAT -Wformat' >& make.log |
b3fe4827 RB |
759 | |
760 | =item * | |
761 | ||
762 | clean up, and print warnings from the log files | |
763 | ||
d2560b70 | 764 | make clean |
b3fe4827 RB |
765 | perl -nwe 'print if /^\S+:/ and not /^make\b/' \ |
766 | mini.log make.log | |
767 | ||
768 | =back | |
d2560b70 RB |
769 | |
770 | (-Wformat support by Robin Barker.) | |
771 | ||
772 | =back | |
773 | ||
d33b2eba | 774 | =head1 Running Purify |
f5a32c7f GS |
775 | |
776 | Purify is a commercial tool that is helpful in identifying memory | |
777 | overruns, wild pointers, memory leaks and other such badness. Perl | |
778 | must be compiled in a specific way for optimal testing with Purify. | |
779 | ||
780 | Use the following commands to test perl with Purify: | |
781 | ||
782 | sh Configure -des -Doptimize=-g -Uusemymalloc -Dusemultiplicity \ | |
783 | -Accflags=-DPURIFY | |
784 | setenv PURIFYOPTIONS "-chain-length=25" | |
785 | make all pureperl | |
786 | cd t | |
787 | ln -s ../pureperl perl | |
365a6279 | 788 | setenv PERL_DESTRUCT_LEVEL 2 |
f5a32c7f GS |
789 | ./perl TEST |
790 | ||
791 | Disabling Perl's malloc allows Purify to monitor allocations and leaks | |
792 | more closely; using Perl's malloc will make Purify report most leaks | |
793 | in the "potential" leaks category. Enabling the multiplicity option | |
794 | allows perl to clean up thoroughly when the interpreter shuts down, which | |
795 | reduces the number of bogus leak reports from Purify. The -DPURIFY | |
796 | enables any Purify-specific debugging code in the sources. | |
797 | ||
798 | Purify outputs messages in "Viewer" windows by default. If you don't have | |
799 | a windowing environment or if you simply want the Purify output to | |
800 | unobtrusively go to a log file instead of to the interactive window, | |
801 | use the following options instead: | |
802 | ||
803 | setenv PURIFYOPTIONS "-chain-length=25 -windows=no -log-file=perl.log \ | |
804 | -append-logfile=yes" | |
805 | ||
806 | The only currently known leaks happen when there are compile-time errors | |
807 | within eval or require. (Fixing these is non-trivial, unfortunately, but | |
808 | they must be fixed eventually.) | |
809 | ||
aa689395 | 810 | =head1 Common Gotcha's |
811 | ||
812 | =over 4 | |
813 | ||
814 | =item #elif | |
815 | ||
816 | The '#elif' preprocessor directive is not understood on all systems. | |
817 | Specifically, I know that Pyramids don't understand it. Thus instead of the | |
818 | simple | |
819 | ||
820 | #if defined(I_FOO) | |
821 | # include <foo.h> | |
822 | #elif defined(I_BAR) | |
823 | # include <bar.h> | |
824 | #else | |
825 | # include <fubar.h> | |
826 | #endif | |
827 | ||
828 | You have to do the more Byzantine | |
829 | ||
830 | #if defined(I_FOO) | |
831 | # include <foo.h> | |
832 | #else | |
833 | # if defined(I_BAR) | |
834 | # include <bar.h> | |
835 | # else | |
836 | # include <fubar.h> | |
837 | # endif | |
838 | #endif | |
839 | ||
840 | Incidentally, whitespace between the leading '#' and the preprocessor | |
841 | command is not guaranteed, but is very portable and you may use it freely. | |
842 | I think it makes things a bit more readable, especially once things get | |
843 | rather deeply nested. I also think that things should almost never get | |
844 | too deeply nested, so it ought to be a moot point :-) | |
845 | ||
846 | =item Probably Prefer POSIX | |
847 | ||
848 | It's often the case that you'll need to choose whether to do | |
849 | something the BSD-ish way or the POSIX-ish way. It's usually not | |
850 | a big problem when the two systems use different names for similar | |
851 | functions, such as memcmp() and bcmp(). The perl.h header file | |
852 | handles these by appropriate #defines, selecting the POSIX mem*() | |
853 | functions if available, but falling back on the b*() functions, if | |
854 | need be. | |
855 | ||
856 | More serious is the case where some brilliant person decided to | |
857 | use the same function name but give it a different meaning or | |
858 | calling sequence :-). getpgrp() and setpgrp() come to mind. | |
859 | These are a real problem on systems that aim for conformance to | |
860 | one standard (e.g. POSIX), but still try to support the other way | |
861 | of doing things (e.g. BSD). My general advice (still not really | |
862 | implemented in the source) is to do something like the following. | |
863 | Suppose there are two alternative versions, fooPOSIX() and | |
864 | fooBSD(). | |
865 | ||
866 | #ifdef HAS_FOOPOSIX | |
867 | /* use fooPOSIX(); */ | |
868 | #else | |
869 | # ifdef HAS_FOOBSD | |
870 | /* try to emulate fooPOSIX() with fooBSD(); | |
871 | perhaps with the following: */ | |
872 | # define fooPOSIX fooBSD | |
873 | # else | |
874 | # /* Uh, oh. We have to supply our own. */ | |
875 | # define fooPOSIX Perl_fooPOSIX | |
876 | # endif | |
877 | #endif | |
878 | ||
879 | =item Think positively | |
880 | ||
881 | If you need to add an #ifdef test, it is usually easier to follow if you | |
882 | think positively, e.g. | |
883 | ||
884 | #ifdef HAS_NEATO_FEATURE | |
885 | /* use neato feature */ | |
886 | #else | |
887 | /* use some fallback mechanism */ | |
888 | #endif | |
889 | ||
890 | rather than the more impenetrable | |
891 | ||
892 | #ifndef MISSING_NEATO_FEATURE | |
893 | /* Not missing it, so we must have it, so use it */ | |
894 | #else | |
895 | /* Are missing it, so fall back on something else. */ | |
896 | #endif | |
897 | ||
898 | Of course for this toy example, there's not much difference. But when | |
899 | the #ifdef's start spanning a couple of screen fulls, and the #else's | |
900 | are marked something like | |
901 | ||
902 | #else /* !MISSING_NEATO_FEATURE */ | |
903 | ||
904 | I find it easy to get lost. | |
905 | ||
906 | =item Providing Missing Functions -- Problem | |
907 | ||
908 | Not all systems have all the neat functions you might want or need, so | |
909 | you might decide to be helpful and provide an emulation. This is | |
910 | sound in theory and very kind of you, but please be careful about what | |
911 | you name the function. Let me use the C<pause()> function as an | |
912 | illustration. | |
913 | ||
914 | Perl5.003 has the following in F<perl.h> | |
915 | ||
916 | #ifndef HAS_PAUSE | |
917 | #define pause() sleep((32767<<16)+32767) | |
918 | #endif | |
919 | ||
920 | Configure sets HAS_PAUSE if the system has the pause() function, so | |
921 | this #define only kicks in if the pause() function is missing. | |
922 | Nice idea, right? | |
923 | ||
924 | Unfortunately, some systems apparently have a prototype for pause() | |
925 | in F<unistd.h>, but don't actually have the function in the library. | |
926 | (Or maybe they do have it in a library we're not using.) | |
927 | ||
928 | Thus, the compiler sees something like | |
929 | ||
930 | extern int pause(void); | |
931 | /* . . . */ | |
932 | #define pause() sleep((32767<<16)+32767) | |
933 | ||
934 | and dies with an error message. (Some compilers don't mind this; | |
935 | others apparently do.) | |
936 | ||
937 | To work around this, 5.003_03 and later have the following in perl.h: | |
938 | ||
939 | /* Some unistd.h's give a prototype for pause() even though | |
940 | HAS_PAUSE ends up undefined. This causes the #define | |
941 | below to be rejected by the compiler. Sigh. | |
942 | */ | |
943 | #ifdef HAS_PAUSE | |
944 | # define Pause pause | |
945 | #else | |
946 | # define Pause() sleep((32767<<16)+32767) | |
947 | #endif | |
948 | ||
949 | This works. | |
950 | ||
951 | The curious reader may wonder why I didn't do the following in | |
952 | F<util.c> instead: | |
953 | ||
954 | #ifndef HAS_PAUSE | |
955 | void pause() | |
956 | { | |
957 | sleep((32767<<16)+32767); | |
958 | } | |
959 | #endif | |
960 | ||
961 | That is, since the function is missing, just provide it. | |
962 | Then things would probably be been alright, it would seem. | |
963 | ||
964 | Well, almost. It could be made to work. The problem arises from the | |
965 | conflicting needs of dynamic loading and namespace protection. | |
966 | ||
967 | For dynamic loading to work on AIX (and VMS) we need to provide a list | |
968 | of symbols to be exported. This is done by the script F<perl_exp.SH>, | |
969 | which reads F<global.sym> and F<interp.sym>. Thus, the C<pause> | |
970 | symbol would have to be added to F<global.sym> So far, so good. | |
971 | ||
972 | On the other hand, one of the goals of Perl5 is to make it easy to | |
973 | either extend or embed perl and link it with other libraries. This | |
974 | means we have to be careful to keep the visible namespace "clean". | |
975 | That is, we don't want perl's global variables to conflict with | |
976 | those in the other application library. Although this work is still | |
977 | in progress, the way it is currently done is via the F<embed.h> file. | |
978 | This file is built from the F<global.sym> and F<interp.sym> files, | |
979 | since those files already list the globally visible symbols. If we | |
980 | had added C<pause> to global.sym, then F<embed.h> would contain the | |
981 | line | |
982 | ||
983 | #define pause Perl_pause | |
984 | ||
985 | and calls to C<pause> in the perl sources would now point to | |
986 | C<Perl_pause>. Now, when B<ld> is run to build the F<perl> executable, | |
987 | it will go looking for C<perl_pause>, which probably won't exist in any | |
988 | of the standard libraries. Thus the build of perl will fail. | |
989 | ||
990 | Those systems where C<HAS_PAUSE> is not defined would be ok, however, | |
991 | since they would get a C<Perl_pause> function in util.c. The rest of | |
992 | the world would be in trouble. | |
993 | ||
994 | And yes, this scenario has happened. On SCO, the function C<chsize> | |
995 | is available. (I think it's in F<-lx>, the Xenix compatibility | |
996 | library.) Since the perl4 days (and possibly before), Perl has | |
997 | included a C<chsize> function that gets called something akin to | |
998 | ||
999 | #ifndef HAS_CHSIZE | |
1000 | I32 chsize(fd, length) | |
1001 | /* . . . */ | |
1002 | #endif | |
1003 | ||
1004 | When 5.003 added | |
1005 | ||
1006 | #define chsize Perl_chsize | |
1007 | ||
1008 | to F<embed.h>, the compile started failing on SCO systems. | |
1009 | ||
1010 | The "fix" is to give the function a different name. The one | |
1011 | implemented in 5.003_05 isn't optimal, but here's what was done: | |
1012 | ||
1013 | #ifdef HAS_CHSIZE | |
1014 | # ifdef my_chsize /* Probably #defined to Perl_my_chsize in embed.h */ | |
1015 | # undef my_chsize | |
1016 | # endif | |
1017 | # define my_chsize chsize | |
1018 | #endif | |
1019 | ||
1020 | My explanatory comment in patch 5.003_05 said: | |
1021 | ||
1022 | Undef and then re-define my_chsize from Perl_my_chsize to | |
1023 | just plain chsize if this system HAS_CHSIZE. This probably only | |
1024 | applies to SCO. This shows the perils of having internal | |
1025 | functions with the same name as external library functions :-). | |
1026 | ||
1027 | Now, we can safely put C<my_chsize> in F<global.sym>, export it, and | |
1028 | hide it with F<embed.h>. | |
1029 | ||
1030 | To be consistent with what I did for C<pause>, I probably should have | |
1031 | called the new function C<Chsize>, rather than C<my_chsize>. | |
1032 | However, the perl sources are quite inconsistent on this (Consider | |
1033 | New, Mymalloc, and Myremalloc, to name just a few.) | |
1034 | ||
1035 | There is a problem with this fix, however, in that C<Perl_chsize> | |
1036 | was available as a F<libperl.a> library function in 5.003, but it | |
1037 | isn't available any more (as of 5.003_07). This means that we've | |
1038 | broken binary compatibility. This is not good. | |
1039 | ||
1040 | =item Providing missing functions -- some ideas | |
1041 | ||
1042 | We currently don't have a standard way of handling such missing | |
1043 | function names. Right now, I'm effectively thinking aloud about a | |
1044 | solution. Some day, I'll try to formally propose a solution. | |
1045 | ||
1046 | Part of the problem is that we want to have some functions listed as | |
1047 | exported but not have their names mangled by embed.h or possibly | |
1048 | conflict with names in standard system headers. We actually already | |
1049 | have such a list at the end of F<perl_exp.SH> (though that list is | |
1050 | out-of-date): | |
1051 | ||
1052 | # extra globals not included above. | |
1053 | cat <<END >> perl.exp | |
1054 | perl_init_ext | |
1055 | perl_init_fold | |
1056 | perl_init_i18nl14n | |
1057 | perl_alloc | |
1058 | perl_construct | |
1059 | perl_destruct | |
1060 | perl_free | |
1061 | perl_parse | |
1062 | perl_run | |
1063 | perl_get_sv | |
1064 | perl_get_av | |
1065 | perl_get_hv | |
1066 | perl_get_cv | |
1067 | perl_call_argv | |
1068 | perl_call_pv | |
1069 | perl_call_method | |
1070 | perl_call_sv | |
1071 | perl_requirepv | |
1072 | safecalloc | |
1073 | safemalloc | |
1074 | saferealloc | |
1075 | safefree | |
1076 | ||
1077 | This still needs much thought, but I'm inclined to think that one | |
1078 | possible solution is to prefix all such functions with C<perl_> in the | |
1079 | source and list them along with the other C<perl_*> functions in | |
1080 | F<perl_exp.SH>. | |
1081 | ||
1082 | Thus, for C<chsize>, we'd do something like the following: | |
1083 | ||
1084 | /* in perl.h */ | |
1085 | #ifdef HAS_CHSIZE | |
1086 | # define perl_chsize chsize | |
1087 | #endif | |
1088 | ||
1089 | then in some file (e.g. F<util.c> or F<doio.c>) do | |
1090 | ||
1091 | #ifndef HAS_CHSIZE | |
1092 | I32 perl_chsize(fd, length) | |
1093 | /* implement the function here . . . */ | |
1094 | #endif | |
1095 | ||
1096 | Alternatively, we could just always use C<chsize> everywhere and move | |
1097 | C<chsize> from F<global.sym> to the end of F<perl_exp.SH>. That would | |
1098 | probably be fine as long as our C<chsize> function agreed with all the | |
1099 | C<chsize> function prototypes in the various systems we'll be using. | |
1100 | As long as the prototypes in actual use don't vary that much, this is | |
1101 | probably a good alternative. (As a counter-example, note how Configure | |
1102 | and perl have to go through hoops to find and use get Malloc_t and | |
1103 | Free_t for C<malloc> and C<free>.) | |
1104 | ||
1105 | At the moment, this latter option is what I tend to prefer. | |
1106 | ||
1107 | =item All the world's a VAX | |
1108 | ||
1109 | Sorry, showing my age:-). Still, all the world is not BSD 4.[34], | |
1110 | SVR4, or POSIX. Be aware that SVR3-derived systems are still quite | |
1111 | common (do you have any idea how many systems run SCO?) If you don't | |
1112 | have a bunch of v7 manuals handy, the metaconfig units (by default | |
1113 | installed in F</usr/local/lib/dist/U>) are a good resource to look at | |
1114 | for portability. | |
1115 | ||
1116 | =back | |
1117 | ||
1118 | =head1 Miscellaneous Topics | |
1119 | ||
1120 | =head2 Autoconf | |
1121 | ||
1122 | Why does perl use a metaconfig-generated Configure script instead of an | |
1123 | autoconf-generated configure script? | |
1124 | ||
1125 | Metaconfig and autoconf are two tools with very similar purposes. | |
1126 | Metaconfig is actually the older of the two, and was originally written | |
1127 | by Larry Wall, while autoconf is probably now used in a wider variety of | |
1128 | packages. The autoconf info file discusses the history of autoconf and | |
1129 | how it came to be. The curious reader is referred there for further | |
1130 | information. | |
1131 | ||
1132 | Overall, both tools are quite good, I think, and the choice of which one | |
1133 | to use could be argued either way. In March, 1994, when I was just | |
1134 | starting to work on Configure support for Perl5, I considered both | |
1135 | autoconf and metaconfig, and eventually decided to use metaconfig for the | |
1136 | following reasons: | |
1137 | ||
1138 | =over 4 | |
1139 | ||
1140 | =item Compatibility with Perl4 | |
1141 | ||
1142 | Perl4 used metaconfig, so many of the #ifdef's were already set up for | |
1143 | metaconfig. Of course metaconfig had evolved some since Perl4's days, | |
1144 | but not so much that it posed any serious problems. | |
1145 | ||
1146 | =item Metaconfig worked for me | |
1147 | ||
d1be9408 | 1148 | My system at the time was Interactive 2.2, an SVR3.2/386 derivative that |
aa689395 | 1149 | also had some POSIX support. Metaconfig-generated Configure scripts |
1150 | worked fine for me on that system. On the other hand, autoconf-generated | |
1151 | scripts usually didn't. (They did come quite close, though, in some | |
1152 | cases.) At the time, I actually fetched a large number of GNU packages | |
1153 | and checked. Not a single one configured and compiled correctly | |
1154 | out-of-the-box with the system's cc compiler. | |
1155 | ||
1156 | =item Configure can be interactive | |
1157 | ||
1158 | With both autoconf and metaconfig, if the script works, everything is | |
1159 | fine. However, one of my main problems with autoconf-generated scripts | |
1160 | was that if it guessed wrong about something, it could be B<very> hard to | |
1161 | go back and fix it. For example, autoconf always insisted on passing the | |
1162 | -Xp flag to cc (to turn on POSIX behavior), even when that wasn't what I | |
1163 | wanted or needed for that package. There was no way short of editing the | |
1164 | configure script to turn this off. You couldn't just edit the resulting | |
1165 | Makefile at the end because the -Xp flag influenced a number of other | |
1166 | configure tests. | |
1167 | ||
1168 | Metaconfig's Configure scripts, on the other hand, can be interactive. | |
1169 | Thus if Configure is guessing things incorrectly, you can go back and fix | |
1170 | them. This isn't as important now as it was when we were actively | |
1171 | developing Configure support for new features such as dynamic loading, | |
1172 | but it's still useful occasionally. | |
1173 | ||
1174 | =item GPL | |
1175 | ||
1176 | At the time, autoconf-generated scripts were covered under the GNU Public | |
1177 | License, and hence weren't suitable for inclusion with Perl, which has a | |
1178 | different licensing policy. (Autoconf's licensing has since changed.) | |
1179 | ||
1180 | =item Modularity | |
1181 | ||
1182 | Metaconfig builds up Configure from a collection of discrete pieces | |
1183 | called "units". You can override the standard behavior by supplying your | |
1184 | own unit. With autoconf, you have to patch the standard files instead. | |
1185 | I find the metaconfig "unit" method easier to work with. Others | |
1186 | may find metaconfig's units clumsy to work with. | |
1187 | ||
1188 | =back | |
1189 | ||
aa689395 | 1190 | =head2 Why isn't there a directory to override Perl's library? |
1191 | ||
1192 | Mainly because no one's gotten around to making one. Note that | |
1193 | "making one" involves changing perl.c, Configure, config_h.SH (and | |
1194 | associated files, see above), and I<documenting> it all in the | |
1195 | INSTALL file. | |
1196 | ||
1197 | Apparently, most folks who want to override one of the standard library | |
1198 | files simply do it by overwriting the standard library files. | |
1199 | ||
1200 | =head2 APPLLIB | |
1201 | ||
1202 | In the perl.c sources, you'll find an undocumented APPLLIB_EXP | |
1203 | variable, sort of like PRIVLIB_EXP and ARCHLIB_EXP (which are | |
1204 | documented in config_h.SH). Here's what APPLLIB_EXP is for, from | |
1205 | a mail message from Larry: | |
1206 | ||
1207 | The main intent of APPLLIB_EXP is for folks who want to send out a | |
1208 | version of Perl embedded in their product. They would set the symbol | |
1209 | to be the name of the library containing the files needed to run or to | |
1210 | support their particular application. This works at the "override" | |
1211 | level to make sure they get their own versions of any library code that | |
1212 | they absolutely must have configuration control over. | |
1213 | ||
1214 | As such, I don't see any conflict with a sysadmin using it for a | |
1215 | override-ish sort of thing, when installing a generic Perl. It should | |
1216 | probably have been named something to do with overriding though. Since | |
1217 | it's undocumented we could still change it... :-) | |
1218 | ||
1219 | Given that it's already there, you can use it to override | |
1220 | distribution modules. If you do | |
1221 | ||
1222 | sh Configure -Dccflags='-DAPPLLIB_EXP=/my/override' | |
1223 | ||
1224 | then perl.c will put /my/override ahead of ARCHLIB and PRIVLIB. | |
1225 | ||
c4f23d77 AD |
1226 | =head2 Shared libperl.so location |
1227 | ||
1228 | Why isn't the shared libperl.so installed in /usr/lib/ along | |
1229 | with "all the other" shared libraries? Instead, it is installed | |
1230 | in $archlib, which is typically something like | |
1231 | ||
1232 | /usr/local/lib/perl5/archname/5.00404 | |
1233 | ||
1234 | and is architecture- and version-specific. | |
1235 | ||
1236 | The basic reason why a shared libperl.so gets put in $archlib is so that | |
1237 | you can have more than one version of perl on the system at the same time, | |
1238 | and have each refer to its own libperl.so. | |
1239 | ||
1240 | Three examples might help. All of these work now; none would work if you | |
1241 | put libperl.so in /usr/lib. | |
1242 | ||
1243 | =over | |
1244 | ||
1245 | =item 1. | |
1246 | ||
1247 | Suppose you want to have both threaded and non-threaded perl versions | |
1248 | around. Configure will name both perl libraries "libperl.so" (so that | |
1249 | you can link to them with -lperl). The perl binaries tell them apart | |
1250 | by having looking in the appropriate $archlib directories. | |
1251 | ||
1252 | =item 2. | |
1253 | ||
1254 | Suppose you have perl5.004_04 installed and you want to try to compile | |
1255 | it again, perhaps with different options or after applying a patch. | |
1256 | If you already have libperl.so installed in /usr/lib/, then it may be | |
1257 | either difficult or impossible to get ld.so to find the new libperl.so | |
1258 | that you're trying to build. If, instead, libperl.so is tucked away in | |
1259 | $archlib, then you can always just change $archlib in the current perl | |
1260 | you're trying to build so that ld.so won't find your old libperl.so. | |
1261 | (The INSTALL file suggests you do this when building a debugging perl.) | |
1262 | ||
1263 | =item 3. | |
1264 | ||
1265 | The shared perl library is not a "well-behaved" shared library with | |
1266 | proper major and minor version numbers, so you can't necessarily | |
1267 | have perl5.004_04 and perl5.004_05 installed simultaneously. Suppose | |
1268 | perl5.004_04 were to install /usr/lib/libperl.so.4.4, and perl5.004_05 | |
1269 | were to install /usr/lib/libperl.so.4.5. Now, when you try to run | |
1270 | perl5.004_04, ld.so might try to load libperl.so.4.5, since it has | |
1271 | the right "major version" number. If this works at all, it almost | |
1272 | certainly defeats the reason for keeping perl5.004_04 around. Worse, | |
1273 | with development subversions, you certaily can't guarantee that | |
1274 | libperl.so.4.4 and libperl.so.4.55 will be compatible. | |
1275 | ||
1276 | Anyway, all this leads to quite obscure failures that are sure to drive | |
1277 | casual users crazy. Even experienced users will get confused :-). Upon | |
1278 | reflection, I'd say leave libperl.so in $archlib. | |
1279 | ||
1280 | =back | |
1281 | ||
aa689395 | 1282 | =head1 Upload Your Work to CPAN |
1283 | ||
1284 | You can upload your work to CPAN if you have a CPAN id. Check out | |
a93751fa | 1285 | http://www.cpan.org/modules/04pause.html for information on |
aa689395 | 1286 | _PAUSE_, the Perl Author's Upload Server. |
1287 | ||
1288 | I typically upload both the patch file, e.g. F<perl5.004_08.pat.gz> | |
1289 | and the full tar file, e.g. F<perl5.004_08.tar.gz>. | |
1290 | ||
1291 | If you want your patch to appear in the F<src/5.0/unsupported> | |
1292 | directory on CPAN, send e-mail to the CPAN master librarian. (Check | |
a93751fa | 1293 | out http://www.cpan.org/CPAN.html ). |
aa689395 | 1294 | |
1295 | =head1 Help Save the World | |
1296 | ||
1297 | You should definitely announce your patch on the perl5-porters list. | |
1298 | You should also consider announcing your patch on | |
1299 | comp.lang.perl.announce, though you should make it quite clear that a | |
1300 | subversion is not a production release, and be prepared to deal with | |
1301 | people who will not read your disclaimer. | |
1302 | ||
1303 | =head1 Todo | |
1304 | ||
1305 | Here, in no particular order, are some Configure and build-related | |
1306 | items that merit consideration. This list isn't exhaustive, it's just | |
1307 | what I came up with off the top of my head. | |
1308 | ||
e25f343d PG |
1309 | =head2 Adding missing library functions to Perl |
1310 | ||
1311 | The perl Configure script automatically determines which headers and | |
1312 | functions you have available on your system and arranges for them to be | |
1313 | included in the compilation and linking process. Occasionally, when porting | |
1314 | perl to an operating system for the first time, you may find that the | |
1315 | operating system is missing a key function. While perl may still build | |
1316 | without this function, no perl program will be able to reference the missing | |
1317 | function. You may be able to write the missing function yourself, or you | |
1318 | may be able to find the missing function in the distribution files for | |
1319 | another software package. In this case, you need to instruct the perl | |
1320 | configure-and-build process to use your function. Perform these steps. | |
1321 | ||
1322 | =over 3 | |
1323 | ||
1324 | =item * | |
1325 | ||
2ecb232b | 1326 | Code and test the function you wish to add. Test it carefully; you will |
e25f343d PG |
1327 | have a much easier time debugging your code independently than when it is a |
1328 | part of perl. | |
1329 | ||
1330 | =item * | |
1331 | ||
1332 | Here is an implementation of the POSIX truncate function for an operating | |
1333 | system (VOS) that does not supply one, but which does supply the ftruncate() | |
1334 | function. | |
1335 | ||
1336 | /* Beginning of modification history */ | |
1337 | /* Written 02-01-02 by Nick Ing-Simmons (nick@ing-simmons.net) */ | |
1338 | /* End of modification history */ | |
1339 | ||
1340 | /* VOS doesn't supply a truncate function, so we build one up | |
1341 | from the available POSIX functions. */ | |
1342 | ||
1343 | #include <fcntl.h> | |
1344 | #include <sys/types.h> | |
1345 | #include <unistd.h> | |
1346 | ||
1347 | int | |
1348 | truncate(const char *path, off_t len) | |
1349 | { | |
1350 | int fd = open(path,O_WRONLY); | |
1351 | int code = -1; | |
1352 | if (fd >= 0) { | |
1353 | code = ftruncate(fd,len); | |
1354 | close(fd); | |
1355 | } | |
1356 | return code; | |
1357 | } | |
1358 | ||
1359 | Place this file into a subdirectory that has the same name as the operating | |
1360 | system. This file is named perl/vos/vos.c | |
1361 | ||
1362 | =item * | |
1363 | ||
1364 | If your operating system has a hints file (in perl/hints/XXX.sh for an | |
1365 | operating system named XXX), then start with it. If your operating system | |
1366 | has no hints file, then create one. You can use a hints file for a similar | |
1367 | operating system, if one exists, as a template. | |
1368 | ||
1369 | =item * | |
1370 | ||
1371 | Add lines like the following to your hints file. The first line | |
1372 | (d_truncate="define") instructs Configure that the truncate() function | |
1373 | exists. The second line (archobjs="vos.o") instructs the makefiles that the | |
1374 | perl executable depends on the existence of a file named "vos.o". (Make | |
1375 | will automatically look for "vos.c" and compile it with the same options as | |
1376 | the perl source code). The final line ("test -h...") adds a symbolic link | |
1377 | to the top-level directory so that make can find vos.c. Of course, you | |
1378 | should use your own operating system name for the source file of extensions, | |
1379 | not "vos.c". | |
1380 | ||
1381 | # VOS does not have truncate() but we supply one in vos.c | |
1382 | d_truncate="define" | |
1383 | archobjs="vos.o" | |
1384 | ||
1385 | # Help gmake find vos.c | |
1386 | test -h vos.c || ln -s vos/vos.c vos.c | |
1387 | ||
1388 | The hints file is a series of shell commands that are run in the top-level | |
1389 | directory (the "perl" directory). Thus, these commands are simply executed | |
1390 | by Configure at an appropriate place during its execution. | |
1391 | ||
1392 | =item * | |
1393 | ||
1394 | At this point, you can run the Configure script and rebuild perl. Carefully | |
1395 | test the newly-built perl to ensure that normal paths, and error paths, | |
1396 | behave as you expect. | |
1397 | ||
1398 | =back | |
1399 | ||
aa689395 | 1400 | =head2 Good ideas waiting for round tuits |
1401 | ||
1402 | =over 4 | |
1403 | ||
c4f23d77 | 1404 | =item Configure -Dsrc=/blah/blah |
aa689395 | 1405 | |
1406 | We should be able to emulate B<configure --srcdir>. Tom Tromey | |
1407 | tromey@creche.cygnus.com has submitted some patches to | |
c4f23d77 AD |
1408 | the dist-users mailing list along these lines. They have been folded |
1409 | back into the main distribution, but various parts of the perl | |
1410 | Configure/build/install process still assume src='.'. | |
aa689395 | 1411 | |
1412 | =item Hint file fixes | |
1413 | ||
1414 | Various hint files work around Configure problems. We ought to fix | |
1415 | Configure so that most of them aren't needed. | |
1416 | ||
1417 | =item Hint file information | |
1418 | ||
1419 | Some of the hint file information (particularly dynamic loading stuff) | |
1420 | ought to be fed back into the main metaconfig distribution. | |
1421 | ||
1422 | =back | |
1423 | ||
1424 | =head2 Probably good ideas waiting for round tuits | |
1425 | ||
1426 | =over 4 | |
1427 | ||
1428 | =item GNU configure --options | |
1429 | ||
1430 | I've received sensible suggestions for --exec_prefix and other | |
1431 | GNU configure --options. It's not always obvious exactly what is | |
1432 | intended, but this merits investigation. | |
1433 | ||
1434 | =item make clean | |
1435 | ||
1436 | Currently, B<make clean> isn't all that useful, though | |
1437 | B<make realclean> and B<make distclean> are. This needs a bit of | |
1438 | thought and documentation before it gets cleaned up. | |
1439 | ||
1440 | =item Try gcc if cc fails | |
1441 | ||
1442 | Currently, we just give up. | |
1443 | ||
1444 | =item bypassing safe*alloc wrappers | |
1445 | ||
1446 | On some systems, it may be safe to call the system malloc directly | |
1447 | without going through the util.c safe* layers. (Such systems would | |
1448 | accept free(0), for example.) This might be a time-saver for systems | |
1449 | that already have a good malloc. (Recent Linux libc's apparently have | |
1450 | a nice malloc that is well-tuned for the system.) | |
1451 | ||
1452 | =back | |
1453 | ||
1454 | =head2 Vague possibilities | |
1455 | ||
1456 | =over 4 | |
1457 | ||
aa689395 | 1458 | =item MacPerl |
1459 | ||
3e3baf6d | 1460 | Get some of the Macintosh stuff folded back into the main distribution. |
aa689395 | 1461 | |
1462 | =item gconvert replacement | |
1463 | ||
1464 | Maybe include a replacement function that doesn't lose data in rare | |
1465 | cases of coercion between string and numerical values. | |
1466 | ||
aa689395 | 1467 | =item Improve makedepend |
1468 | ||
1469 | The current makedepend process is clunky and annoyingly slow, but it | |
1470 | works for most folks. Alas, it assumes that there is a filename | |
1471 | $firstmakefile that the B<make> command will try to use before it uses | |
1472 | F<Makefile>. Such may not be the case for all B<make> commands, | |
1473 | particularly those on non-Unix systems. | |
1474 | ||
1475 | Probably some variant of the BSD F<.depend> file will be useful. | |
1476 | We ought to check how other packages do this, if they do it at all. | |
1477 | We could probably pre-generate the dependencies (with the exception of | |
1478 | malloc.o, which could probably be determined at F<Makefile.SH> | |
1479 | extraction time. | |
1480 | ||
1481 | =item GNU Makefile standard targets | |
1482 | ||
1483 | GNU software generally has standardized Makefile targets. Unless we | |
1484 | have good reason to do otherwise, I see no reason not to support them. | |
1485 | ||
1486 | =item File locking | |
1487 | ||
1488 | Somehow, straighten out, document, and implement lockf(), flock(), | |
76ba0908 PK |
1489 | and/or fcntl() file locking. It's a mess. See $d_fcntl_can_lock |
1490 | in recent config.sh files though. | |
aa689395 | 1491 | |
1492 | =back | |
1493 | ||
fb73857a | 1494 | =head1 AUTHORS |
aa689395 | 1495 | |
fb73857a | 1496 | Original author: Andy Dougherty doughera@lafcol.lafayette.edu . |
1497 | Additions by Chip Salzenberg chip@perl.com and | |
1498 | Tim Bunce Tim.Bunce@ig.co.uk . | |
aa689395 | 1499 | |
1500 | All opinions expressed herein are those of the authorZ<>(s). | |
1501 | ||
1502 | =head1 LAST MODIFIED | |
1503 | ||
ff935051 | 1504 | $Id: pumpkin.pod,v 1.23 2000/01/13 19:45:13 doughera Released $ |