"Fossies" - the Fresh Open Source Software Archive

Member "perl-5.30.3/README.os2" (14 May 2020, 93350 Bytes) of package /linux/misc/perl-5.30.3.tar.xz:


As a special service "Fossies" has tried to format the requested text file into HTML format (style: standard) with prefixed line numbers. Alternatively you can here view or download the uninterpreted source code file. See also the latest Fossies "Diffs" side-by-side code changes report for "README.os2": 5.30.2_vs_5.30.3.

    1 If you read this file _as_is_, just ignore the funny characters you
    2 see. It is written in the POD format (see perlpod manpage) which is
    3 specially designed to be readable as is.
    4 
    5 =head1 NAME
    6 
    7 perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT.
    8 
    9 =head1 SYNOPSIS
   10 
   11 One can read this document in the following formats:
   12 
   13 	man perlos2
   14 	view perl perlos2
   15 	explorer perlos2.html
   16 	info perlos2
   17 
   18 to list some (not all may be available simultaneously), or it may
   19 be read I<as is>: either as F<README.os2>, or F<pod/perlos2.pod>.
   20 
   21 To read the F<.INF> version of documentation (B<very> recommended)
   22 outside of OS/2, one needs an IBM's reader (may be available on IBM
   23 ftp sites (?)  (URL anyone?)) or shipped with PC DOS 7.0 and IBM's
   24 Visual Age C++ 3.5.
   25 
   26 A copy of a Win* viewer is contained in the "Just add OS/2 Warp" package
   27 
   28   ftp://ftp.software.ibm.com/ps/products/os2/tools/jaow/jaow.zip
   29 
   30 in F<?:\JUST_ADD\view.exe>. This gives one an access to EMX's 
   31 F<.INF> docs as well (text form is available in F</emx/doc> in 
   32 EMX's distribution).  There is also a different viewer named xview.
   33 
   34 Note that if you have F<lynx.exe> or F<netscape.exe> installed, you can follow WWW links
   35 from this document in F<.INF> format. If you have EMX docs installed 
   36 correctly, you can follow library links (you need to have C<view emxbook>
   37 working by setting C<EMXBOOK> environment variable as it is described
   38 in EMX docs).
   39 
   40 =cut
   41 
   42 Contents (This may be a little bit obsolete)
   43  
   44  perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT.
   45 
   46       NAME
   47       SYNOPSIS
   48       DESCRIPTION
   49 	 -  Target
   50 	 -  Other OSes
   51 	 -  Prerequisites
   52 	 -  Starting Perl programs under OS/2 (and DOS and...)
   53 	 -  Starting OS/2 (and DOS) programs under Perl
   54       Frequently asked questions
   55 	 -  "It does not work"
   56 	 -  I cannot run external programs
   57 	 -  I cannot embed perl into my program, or use perl.dll from my
   58 	 -  `` and pipe-open do not work under DOS.
   59 	 -  Cannot start find.exe "pattern" file
   60       INSTALLATION
   61 	 -  Automatic binary installation
   62 	 -  Manual binary installation
   63 	 -  Warning
   64       Accessing documentation
   65 	 -  OS/2 .INF file
   66 	 -  Plain text
   67 	 -  Manpages
   68 	 -  HTML
   69 	 -  GNU info files
   70 	 -  PDF files
   71 	 -  LaTeX docs
   72       BUILD
   73 	 -  The short story
   74 	 -  Prerequisites
   75 	 -  Getting perl source
   76 	 -  Application of the patches
   77 	 -  Hand-editing
   78 	 -  Making
   79 	 -  Testing
   80 	 -  Installing the built perl
   81 	 -  a.out-style build
   82       Build FAQ
   83 	 -  Some / became \ in pdksh.
   84 	 -  'errno' - unresolved external
   85 	 -  Problems with tr or sed
   86 	 -  Some problem (forget which ;-)
   87 	 -  Library ... not found
   88 	 -  Segfault in make
   89 	 -  op/sprintf test failure
   90       Specific (mis)features of OS/2 port
   91 	 -  setpriority, getpriority
   92 	 -  system()
   93 	 -  extproc on the first line
   94 	 -  Additional modules:
   95 	 -  Prebuilt methods:
   96 	 -  Prebuilt variables:
   97 	 -  Misfeatures
   98 	 -  Modifications
   99 	 -  Identifying DLLs
  100 	 -  Centralized management of resources
  101       Perl flavors
  102 	 -  perl.exe
  103 	 -  perl_.exe
  104 	 -  perl__.exe
  105 	 -  perl___.exe
  106 	 -  Why strange names?
  107 	 -  Why dynamic linking?
  108 	 -  Why chimera build?
  109       ENVIRONMENT
  110 	 -  PERLLIB_PREFIX
  111 	 -  PERL_BADLANG
  112 	 -  PERL_BADFREE
  113 	 -  PERL_SH_DIR
  114 	 -  USE_PERL_FLOCK
  115 	 -  TMP or TEMP
  116       Evolution
  117 	 -  Text-mode filehandles
  118 	 -  Priorities
  119 	 -  DLL name mangling: pre 5.6.2
  120 	 -  DLL name mangling: 5.6.2 and beyond
  121 	 -  DLL forwarder generation
  122 	 -  Threading
  123 	 -  Calls to external programs
  124 	 -  Memory allocation
  125 	 -  Threads
  126       BUGS
  127       AUTHOR
  128       SEE ALSO
  129 
  130 =head1 DESCRIPTION
  131 
  132 =head2 Target
  133 
  134 The target is to make OS/2 one of the best supported platform for
  135 using/building/developing Perl and I<Perl applications>, as well as
  136 make Perl the best language to use under OS/2. The secondary target is
  137 to try to make this work under DOS and Win* as well (but not B<too> hard).
  138 
  139 The current state is quite close to this target. Known limitations:
  140 
  141 =over 5
  142 
  143 =item *
  144 
  145 Some *nix programs use fork() a lot; with the mostly useful flavors of
  146 perl for OS/2 (there are several built simultaneously) this is
  147 supported; but some flavors do not support this (e.g., when Perl is
  148 called from inside REXX).  Using fork() after
  149 I<use>ing dynamically loading extensions would not work with I<very> old
  150 versions of EMX.
  151 
  152 =item *
  153 
  154 You need a separate perl executable F<perl__.exe> (see L</perl__.exe>)
  155 if you want to use PM code in your application (as Perl/Tk or OpenGL
  156 Perl modules do) without having a text-mode window present.
  157 
  158 While using the standard F<perl.exe> from a text-mode window is possible
  159 too, I have seen cases when this causes degradation of the system stability.
  160 Using F<perl__.exe> avoids such a degradation.
  161 
  162 =item *
  163 
  164 There is no simple way to access WPS objects. The only way I know
  165 is via C<OS2::REXX> and C<SOM> extensions (see L<OS2::REXX>, L<SOM>).
  166 However, we do not have access to
  167 convenience methods of Object-REXX. (Is it possible at all? I know
  168 of no Object-REXX API.)  The C<SOM> extension (currently in alpha-text)
  169 may eventually remove this shortcoming; however, due to the fact that
  170 DII is not supported by the C<SOM> module, using C<SOM> is not as
  171 convenient as one would like it.
  172 
  173 =back
  174 
  175 Please keep this list up-to-date by informing me about other items.
  176 
  177 =head2 Other OSes
  178 
  179 Since OS/2 port of perl uses a remarkable EMX environment, it can
  180 run (and build extensions, and - possibly - be built itself) under any
  181 environment which can run EMX. The current list is DOS,
  182 DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT. Out of many perl flavors,
  183 only one works, see L</"F<perl_.exe>">.
  184 
  185 Note that not all features of Perl are available under these
  186 environments. This depends on the features the I<extender> - most
  187 probably RSX - decided to implement.
  188 
  189 Cf. L</Prerequisites>.
  190 
  191 =head2 Prerequisites
  192 
  193 =over 6
  194 
  195 =item EMX
  196 
  197 EMX runtime is required (may be substituted by RSX). Note that
  198 it is possible to make F<perl_.exe> to run under DOS without any
  199 external support by binding F<emx.exe>/F<rsx.exe> to it, see C<emxbind>. Note
  200 that under DOS for best results one should use RSX runtime, which
  201 has much more functions working (like C<fork>, C<popen> and so on). In
  202 fact RSX is required if there is no VCPI present. Note the
  203 RSX requires DPMI.  Many implementations of DPMI are known to be very
  204 buggy, beware!
  205 
  206 Only the latest runtime is supported, currently C<0.9d fix 03>. Perl may run
  207 under earlier versions of EMX, but this is not tested.
  208 
  209 One can get different parts of EMX from, say
  210 
  211   ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/emx+gcc/
  212   http://hobbes.nmsu.edu/h-browse.php?dir=/pub/os2/dev/emx/v0.9d/
  213 
  214 The runtime component should have the name F<emxrt.zip>.
  215 
  216 B<NOTE>. When using F<emx.exe>/F<rsx.exe>, it is enough to have them on your path. One
  217 does not need to specify them explicitly (though this
  218 
  219   emx perl_.exe -de 0
  220 
  221 will work as well.)
  222 
  223 =item RSX
  224 
  225 To run Perl on DPMI platforms one needs RSX runtime. This is
  226 needed under DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT (see 
  227 L</"Other OSes">). RSX would not work with VCPI
  228 only, as EMX would, it requires DMPI.
  229 
  230 Having RSX and the latest F<sh.exe> one gets a fully functional
  231 B<*nix>-ish environment under DOS, say, C<fork>, C<``> and
  232 pipe-C<open> work. In fact, MakeMaker works (for static build), so one
  233 can have Perl development environment under DOS. 
  234 
  235 One can get RSX from, say
  236 
  237   http://cd.textfiles.com/hobbesos29804/disk1/EMX09C/
  238   ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/emx+gcc/contrib/
  239 
  240 Contact the author on C<rainer@mathematik.uni-bielefeld.de>.
  241 
  242 The latest F<sh.exe> with DOS hooks is available in
  243 
  244   http://www.ilyaz.org/software/os2/
  245 
  246 as F<sh_dos.zip> or under similar names starting with C<sh>, C<pdksh> etc.
  247 
  248 =item HPFS
  249 
  250 Perl does not care about file systems, but the perl library contains
  251 many files with long names, so to install it intact one needs a file
  252 system which supports long file names.
  253 
  254 Note that if you do not plan to build the perl itself, it may be
  255 possible to fool EMX to truncate file names. This is not supported,
  256 read EMX docs to see how to do it.
  257 
  258 =item pdksh
  259 
  260 To start external programs with complicated command lines (like with
  261 pipes in between, and/or quoting of arguments), Perl uses an external
  262 shell. With EMX port such shell should be named F<sh.exe>, and located
  263 either in the wired-in-during-compile locations (usually F<F:/bin>),
  264 or in configurable location (see L</"C<PERL_SH_DIR>">).
  265 
  266 For best results use EMX pdksh. The standard binary (5.2.14 or later) runs
  267 under DOS (with L</RSX>) as well, see
  268 
  269   http://www.ilyaz.org/software/os2/
  270 
  271 =back
  272 
  273 =head2 Starting Perl programs under OS/2 (and DOS and...)
  274 
  275 Start your Perl program F<foo.pl> with arguments C<arg1 arg2 arg3> the
  276 same way as on any other platform, by
  277 
  278 	perl foo.pl arg1 arg2 arg3
  279 
  280 If you want to specify perl options C<-my_opts> to the perl itself (as
  281 opposed to your program), use
  282 
  283 	perl -my_opts foo.pl arg1 arg2 arg3
  284 
  285 Alternately, if you use OS/2-ish shell, like CMD or 4os2, put
  286 the following at the start of your perl script:
  287 
  288 	extproc perl -S -my_opts
  289 
  290 rename your program to F<foo.cmd>, and start it by typing
  291 
  292 	foo arg1 arg2 arg3
  293 
  294 Note that because of stupid OS/2 limitations the full path of the perl
  295 script is not available when you use C<extproc>, thus you are forced to
  296 use C<-S> perl switch, and your script should be on the C<PATH>. As a plus
  297 side, if you know a full path to your script, you may still start it
  298 with 
  299 
  300 	perl ../../blah/foo.cmd arg1 arg2 arg3
  301 
  302 (note that the argument C<-my_opts> is taken care of by the C<extproc> line
  303 in your script, see L<C<extproc> on the first line>).
  304 
  305 To understand what the above I<magic> does, read perl docs about C<-S>
  306 switch - see L<perlrun>, and cmdref about C<extproc>:
  307 
  308 	view perl perlrun
  309 	man perlrun
  310 	view cmdref extproc
  311 	help extproc
  312 
  313 or whatever method you prefer.
  314 
  315 There are also endless possibilities to use I<executable extensions> of
  316 4os2, I<associations> of WPS and so on... However, if you use
  317 *nixish shell (like F<sh.exe> supplied in the binary distribution),
  318 you need to follow the syntax specified in L<perlrun/"Command Switches">.
  319 
  320 Note that B<-S> switch supports scripts with additional extensions 
  321 F<.cmd>, F<.btm>, F<.bat>, F<.pl> as well.
  322 
  323 =head2 Starting OS/2 (and DOS) programs under Perl
  324 
  325 This is what system() (see L<perlfunc/system>), C<``> (see
  326 L<perlop/"I/O Operators">), and I<open pipe> (see L<perlfunc/open>)
  327 are for. (Avoid exec() (see L<perlfunc/exec>) unless you know what you
  328 do).
  329 
  330 Note however that to use some of these operators you need to have a
  331 sh-syntax shell installed (see L</"Pdksh">, 
  332 L</"Frequently asked questions">), and perl should be able to find it
  333 (see L</"C<PERL_SH_DIR>">).
  334 
  335 The cases when the shell is used are:
  336 
  337 =over
  338 
  339 =item 1
  340 
  341 One-argument system() (see L<perlfunc/system>), exec() (see L<perlfunc/exec>)
  342 with redirection or shell meta-characters;
  343 
  344 =item 2
  345 
  346 Pipe-open (see L<perlfunc/open>) with the command which contains redirection 
  347 or shell meta-characters;
  348 
  349 =item 3
  350 
  351 Backticks C<``> (see L<perlop/"I/O Operators">) with the command which contains
  352 redirection or shell meta-characters;
  353 
  354 =item 4
  355 
  356 If the executable called by system()/exec()/pipe-open()/C<``> is a script
  357 with the "magic" C<#!> line or C<extproc> line which specifies shell;
  358 
  359 =item 5
  360 
  361 If the executable called by system()/exec()/pipe-open()/C<``> is a script
  362 without "magic" line, and C<$ENV{EXECSHELL}> is set to shell;
  363 
  364 =item 6
  365 
  366 If the executable called by system()/exec()/pipe-open()/C<``> is not
  367 found (is not this remark obsolete?);
  368 
  369 =item 7
  370 
  371 For globbing (see L<perlfunc/glob>, L<perlop/"I/O Operators">)
  372 (obsolete? Perl uses builtin globbing nowadays...).
  373 
  374 =back
  375 
  376 For the sake of speed for a common case, in the above algorithms 
  377 backslashes in the command name are not considered as shell metacharacters.
  378 
  379 Perl starts scripts which begin with cookies
  380 C<extproc> or C<#!> directly, without an intervention of shell.  Perl uses the
  381 same algorithm to find the executable as F<pdksh>: if the path
  382 on C<#!> line does not work, and contains C</>, then the directory
  383 part of the executable is ignored, and the executable
  384 is searched in F<.> and on C<PATH>.  To find arguments for these scripts
  385 Perl uses a different algorithm than F<pdksh>: up to 3 arguments are 
  386 recognized, and trailing whitespace is stripped.
  387 
  388 If a script
  389 does not contain such a cooky, then to avoid calling F<sh.exe>, Perl uses
  390 the same algorithm as F<pdksh>: if C<$ENV{EXECSHELL}> is set, the
  391 script is given as the first argument to this command, if not set, then
  392 C<$ENV{COMSPEC} /c> is used (or a hardwired guess if C<$ENV{COMSPEC}> is
  393 not set).
  394 
  395 When starting scripts directly, Perl uses exactly the same algorithm as for 
  396 the search of script given by B<-S> command-line option: it will look in
  397 the current directory, then on components of C<$ENV{PATH}> using the 
  398 following order of appended extensions: no extension, F<.cmd>, F<.btm>, 
  399 F<.bat>, F<.pl>.
  400 
  401 Note that Perl will start to look for scripts only if OS/2 cannot start the
  402 specified application, thus C<system 'blah'> will not look for a script if 
  403 there is an executable file F<blah.exe> I<anywhere> on C<PATH>.  In
  404 other words, C<PATH> is essentially searched twice: once by the OS for
  405 an executable, then by Perl for scripts.
  406 
  407 Note also that executable files on OS/2 can have an arbitrary extension, but
  408 F<.exe> will be automatically appended if no dot is present in the name.  The
  409 workaround is as simple as that:  since F<blah.> and F<blah> denote the same
  410 file (at list on FAT and HPFS file systems), to start an executable residing in
  411 file F<n:/bin/blah> (no extension) give an argument C<n:/bin/blah.> (dot
  412 appended) to system().
  413 
  414 Perl will start PM programs from VIO (=text-mode) Perl process in a
  415 separate PM session;
  416 the opposite is not true: when you start a non-PM program from a PM
  417 Perl process, Perl would not run it in a separate session.  If a separate
  418 session is desired, either ensure
  419 that shell will be used, as in C<system 'cmd /c myprog'>, or start it using
  420 optional arguments to system() documented in C<OS2::Process> module.  This
  421 is considered to be a feature.
  422 
  423 =head1 Frequently asked questions
  424 
  425 =head2 "It does not work"
  426 
  427 Perl binary distributions come with a F<testperl.cmd> script which tries
  428 to detect common problems with misconfigured installations.  There is a
  429 pretty large chance it will discover which step of the installation you
  430 managed to goof.  C<;-)>
  431 
  432 =head2 I cannot run external programs
  433 
  434 =over 4
  435 
  436 =item *
  437 
  438 Did you run your programs with C<-w> switch? See 
  439 L<Starting OSE<sol>2 (and DOS) programs under Perl>.
  440 
  441 =item *
  442 
  443 Do you try to run I<internal> shell commands, like C<`copy a b`>
  444 (internal for F<cmd.exe>), or C<`glob a*b`> (internal for ksh)? You
  445 need to specify your shell explicitly, like C<`cmd /c copy a b`>,
  446 since Perl cannot deduce which commands are internal to your shell.
  447 
  448 =back
  449 
  450 =head2 I cannot embed perl into my program, or use F<perl.dll> from my
  451 program. 
  452 
  453 =over 4
  454 
  455 =item Is your program EMX-compiled with C<-Zmt -Zcrtdll>?
  456 
  457 Well, nowadays Perl DLL should be usable from a differently compiled
  458 program too...  If you can run Perl code from REXX scripts (see
  459 L<OS2::REXX>), then there are some other aspect of interaction which
  460 are overlooked by the current hackish code to support
  461 differently-compiled principal programs.
  462 
  463 If everything else fails, you need to build a stand-alone DLL for
  464 perl. Contact me, I did it once. Sockets would not work, as a lot of
  465 other stuff.
  466 
  467 =item Did you use L<ExtUtils::Embed>?
  468 
  469 Some time ago I had reports it does not work.  Nowadays it is checked
  470 in the Perl test suite, so grep F<./t> subdirectory of the build tree
  471 (as well as F<*.t> files in the F<./lib> subdirectory) to find how it
  472 should be done "correctly".
  473 
  474 =back
  475 
  476 =head2 C<``> and pipe-C<open> do not work under DOS.
  477 
  478 This may a variant of just L</"I cannot run external programs">, or a
  479 deeper problem. Basically: you I<need> RSX (see L</Prerequisites>)
  480 for these commands to work, and you may need a port of F<sh.exe> which
  481 understands command arguments. One of such ports is listed in
  482 L</Prerequisites> under RSX. Do not forget to set variable
  483 L</"C<PERL_SH_DIR>"> as well.
  484 
  485 DPMI is required for RSX.
  486 
  487 =head2 Cannot start C<find.exe "pattern" file>
  488 
  489 The whole idea of the "standard C API to start applications" is that
  490 the forms C<foo> and C<"foo"> of program arguments are completely
  491 interchangeable.  F<find> breaks this paradigm;
  492 
  493   find "pattern" file
  494   find pattern file
  495 
  496 are not equivalent; F<find> cannot be started directly using the above
  497 API.  One needs a way to surround the doublequotes in some other
  498 quoting construction, necessarily having an extra non-Unixish shell in
  499 between.
  500 
  501 Use one of
  502 
  503   system 'cmd', '/c', 'find "pattern" file';
  504   `cmd /c 'find "pattern" file'`
  505 
  506 This would start F<find.exe> via F<cmd.exe> via C<sh.exe> via
  507 C<perl.exe>, but this is a price to pay if you want to use
  508 non-conforming program.
  509 
  510 =head1 INSTALLATION
  511 
  512 =head2 Automatic binary installation
  513 
  514 The most convenient way of installing a binary distribution of perl is via perl installer
  515 F<install.exe>. Just follow the instructions, and 99% of the
  516 installation blues would go away. 
  517 
  518 Note however, that you need to have F<unzip.exe> on your path, and
  519 EMX environment I<running>. The latter means that if you just
  520 installed EMX, and made all the needed changes to F<Config.sys>,
  521 you may need to reboot in between. Check EMX runtime by running
  522 
  523 	emxrev
  524 
  525 Binary installer also creates a folder on your desktop with some useful
  526 objects.  If you need to change some aspects of the work of the binary
  527 installer, feel free to edit the file F<Perl.pkg>.  This may be useful
  528 e.g., if you need to run the installer many times and do not want to
  529 make many interactive changes in the GUI.
  530 
  531 B<Things not taken care of by automatic binary installation:>
  532 
  533 =over 15
  534 
  535 =item C<PERL_BADLANG>
  536 
  537 may be needed if you change your codepage I<after> perl installation,
  538 and the new value is not supported by EMX. See L</"C<PERL_BADLANG>">.
  539 
  540 =item C<PERL_BADFREE>
  541 
  542 see L</"C<PERL_BADFREE>">.
  543 
  544 =item F<Config.pm>
  545 
  546 This file resides somewhere deep in the location you installed your
  547 perl library, find it out by 
  548 
  549   perl -MConfig -le "print $INC{'Config.pm'}"
  550 
  551 While most important values in this file I<are> updated by the binary
  552 installer, some of them may need to be hand-edited. I know no such
  553 data, please keep me informed if you find one.  Moreover, manual
  554 changes to the installed version may need to be accompanied by an edit
  555 of this file.
  556 
  557 =back
  558 
  559 B<NOTE>. Because of a typo the binary installer of 5.00305
  560 would install a variable C<PERL_SHPATH> into F<Config.sys>. Please
  561 remove this variable and put L</C<PERL_SH_DIR>> instead.
  562 
  563 =head2 Manual binary installation
  564 
  565 As of version 5.00305, OS/2 perl binary distribution comes split
  566 into 11 components. Unfortunately, to enable configurable binary
  567 installation, the file paths in the zip files are not absolute, but
  568 relative to some directory.
  569 
  570 Note that the extraction with the stored paths is still necessary
  571 (default with unzip, specify C<-d> to pkunzip). However, you
  572 need to know where to extract the files. You need also to manually
  573 change entries in F<Config.sys> to reflect where did you put the
  574 files. Note that if you have some primitive unzipper (like
  575 C<pkunzip>), you may get a lot of warnings/errors during
  576 unzipping. Upgrade to C<(w)unzip>.
  577 
  578 Below is the sample of what to do to reproduce the configuration on my
  579 machine.  In F<VIEW.EXE> you can press C<Ctrl-Insert> now, and
  580 cut-and-paste from the resulting file - created in the directory you
  581 started F<VIEW.EXE> from.
  582 
  583 For each component, we mention environment variables related to each
  584 installation directory.  Either choose directories to match your
  585 values of the variables, or create/append-to variables to take into
  586 account the directories.
  587 
  588 =over 3
  589 
  590 =item Perl VIO and PM executables (dynamically linked)
  591 
  592   unzip perl_exc.zip *.exe *.ico -d f:/emx.add/bin
  593   unzip perl_exc.zip *.dll -d f:/emx.add/dll
  594 
  595 (have the directories with C<*.exe> on PATH, and C<*.dll> on
  596 LIBPATH);
  597 
  598 =item Perl_ VIO executable (statically linked)
  599 
  600   unzip perl_aou.zip -d f:/emx.add/bin
  601 
  602 (have the directory on PATH);
  603 
  604 =item Executables for Perl utilities
  605 
  606   unzip perl_utl.zip -d f:/emx.add/bin
  607 
  608 (have the directory on PATH);
  609 
  610 =item Main Perl library
  611 
  612   unzip perl_mlb.zip -d f:/perllib/lib
  613 
  614 If this directory is exactly the same as the prefix which was compiled
  615 into F<perl.exe>, you do not need to change
  616 anything. However, for perl to find the library if you use a different
  617 path, you need to
  618 C<set PERLLIB_PREFIX> in F<Config.sys>, see L</"C<PERLLIB_PREFIX>">.
  619 
  620 =item Additional Perl modules
  621 
  622   unzip perl_ste.zip -d f:/perllib/lib/site_perl/5.30.3/
  623 
  624 Same remark as above applies.  Additionally, if this directory is not
  625 one of directories on @INC (and @INC is influenced by C<PERLLIB_PREFIX>), you
  626 need to put this
  627 directory and subdirectory F<./os2> in C<PERLLIB> or C<PERL5LIB>
  628 variable. Do not use C<PERL5LIB> unless you have it set already. See
  629 L<perl/"ENVIRONMENT">.
  630 
  631 B<[Check whether this extraction directory is still applicable with
  632 the new directory structure layout!]>
  633 
  634 =item Tools to compile Perl modules
  635 
  636   unzip perl_blb.zip -d f:/perllib/lib
  637 
  638 Same remark as for F<perl_ste.zip>.
  639 
  640 =item Manpages for Perl and utilities
  641 
  642   unzip perl_man.zip -d f:/perllib/man
  643 
  644 This directory should better be on C<MANPATH>. You need to have a
  645 working F<man> to access these files.
  646 
  647 =item Manpages for Perl modules
  648 
  649   unzip perl_mam.zip -d f:/perllib/man
  650 
  651 This directory should better be on C<MANPATH>. You need to have a
  652 working man to access these files.
  653 
  654 =item Source for Perl documentation
  655 
  656   unzip perl_pod.zip -d f:/perllib/lib
  657 
  658 This is used by the C<perldoc> program (see L<perldoc>), and may be used to
  659 generate HTML documentation usable by WWW browsers, and
  660 documentation in zillions of other formats: C<info>, C<LaTeX>,
  661 C<Acrobat>, C<FrameMaker> and so on.  [Use programs such as
  662 F<pod2latex> etc.]
  663 
  664 =item Perl manual in F<.INF> format
  665 
  666   unzip perl_inf.zip -d d:/os2/book
  667 
  668 This directory should better be on C<BOOKSHELF>.
  669 
  670 =item Pdksh
  671 
  672   unzip perl_sh.zip -d f:/bin
  673 
  674 This is used by perl to run external commands which explicitly
  675 require shell, like the commands using I<redirection> and I<shell
  676 metacharacters>. It is also used instead of explicit F</bin/sh>.
  677 
  678 Set C<PERL_SH_DIR> (see L</"C<PERL_SH_DIR>">) if you move F<sh.exe> from
  679 the above location.
  680 
  681 B<Note.> It may be possible to use some other sh-compatible shell (untested).
  682 
  683 =back
  684 
  685 After you installed the components you needed and updated the
  686 F<Config.sys> correspondingly, you need to hand-edit
  687 F<Config.pm>. This file resides somewhere deep in the location you
  688 installed your perl library, find it out by
  689 
  690   perl -MConfig -le "print $INC{'Config.pm'}"
  691 
  692 You need to correct all the entries which look like file paths (they
  693 currently start with C<f:/>).
  694 
  695 =head2 B<Warning>
  696 
  697 The automatic and manual perl installation leave precompiled paths
  698 inside perl executables. While these paths are overwritable (see
  699 L</"C<PERLLIB_PREFIX>">, L</"C<PERL_SH_DIR>">), some people may prefer
  700 binary editing of paths inside the executables/DLLs.
  701 
  702 =head1 Accessing documentation
  703 
  704 Depending on how you built/installed perl you may have (otherwise
  705 identical) Perl documentation in the following formats:
  706 
  707 =head2 OS/2 F<.INF> file
  708 
  709 Most probably the most convenient form. Under OS/2 view it as
  710 
  711   view perl
  712   view perl perlfunc
  713   view perl less
  714   view perl ExtUtils::MakeMaker
  715 
  716 (currently the last two may hit a wrong location, but this may improve
  717 soon). Under Win* see L</"SYNOPSIS">.
  718 
  719 If you want to build the docs yourself, and have I<OS/2 toolkit>, run
  720 
  721 	pod2ipf > perl.ipf
  722 
  723 in F</perllib/lib/pod> directory, then
  724 
  725 	ipfc /inf perl.ipf
  726 
  727 (Expect a lot of errors during the both steps.) Now move it on your
  728 BOOKSHELF path.
  729 
  730 =head2 Plain text
  731 
  732 If you have perl documentation in the source form, perl utilities
  733 installed, and GNU groff installed, you may use 
  734 
  735 	perldoc perlfunc
  736 	perldoc less
  737 	perldoc ExtUtils::MakeMaker
  738 
  739 to access the perl documentation in the text form (note that you may get
  740 better results using perl manpages).
  741 
  742 Alternately, try running pod2text on F<.pod> files.
  743 
  744 =head2 Manpages
  745 
  746 If you have F<man> installed on your system, and you installed perl
  747 manpages, use something like this:
  748 
  749 	man perlfunc
  750 	man 3 less
  751 	man ExtUtils.MakeMaker
  752 
  753 to access documentation for different components of Perl. Start with
  754 
  755 	man perl
  756 
  757 Note that dot (F<.>) is used as a package separator for documentation
  758 for packages, and as usual, sometimes you need to give the section - C<3>
  759 above - to avoid shadowing by the I<less(1) manpage>.
  760 
  761 Make sure that the directory B<above> the directory with manpages is
  762 on our C<MANPATH>, like this
  763 
  764   set MANPATH=c:/man;f:/perllib/man
  765 
  766 for Perl manpages in C<f:/perllib/man/man1/> etc.
  767 
  768 =head2 HTML
  769 
  770 If you have some WWW browser available, installed the Perl
  771 documentation in the source form, and Perl utilities, you can build
  772 HTML docs. Cd to directory with F<.pod> files, and do like this
  773 
  774 	cd f:/perllib/lib/pod
  775 	pod2html
  776 
  777 After this you can direct your browser the file F<perl.html> in this
  778 directory, and go ahead with reading docs, like this:
  779 
  780 	explore file:///f:/perllib/lib/pod/perl.html
  781 
  782 Alternatively you may be able to get these docs prebuilt from CPAN.
  783 
  784 =head2 GNU C<info> files
  785 
  786 Users of Emacs would appreciate it very much, especially with
  787 C<CPerl> mode loaded. You need to get latest C<pod2texi> from C<CPAN>,
  788 or, alternately, the prebuilt info pages.
  789 
  790 =head2 F<PDF> files
  791 
  792 for C<Acrobat> are available on CPAN (may be for slightly older version of
  793 perl).
  794 
  795 =head2 C<LaTeX> docs
  796 
  797 can be constructed using C<pod2latex>.
  798 
  799 =head1 BUILD
  800 
  801 Here we discuss how to build Perl under OS/2.
  802 
  803 =head2 The short story
  804 
  805 Assume that you are a seasoned porter, so are sure that all the necessary
  806 tools are already present on your system, and you know how to get the Perl
  807 source distribution.  Untar it, change to the extract directory, and
  808 
  809   gnupatch -p0 < os2\diff.configure
  810   sh Configure -des -D prefix=f:/perllib
  811   make
  812   make test
  813   make install
  814   make aout_test
  815   make aout_install
  816 
  817 This puts the executables in f:/perllib/bin.  Manually move them to the
  818 C<PATH>, manually move the built F<perl*.dll> to C<LIBPATH> (here for
  819 Perl DLL F<*> is a not-very-meaningful hex checksum), and run
  820 
  821   make installcmd INSTALLCMDDIR=d:/ir/on/path
  822 
  823 Assuming that the C<man>-files were put on an appropriate location,
  824 this completes the installation of minimal Perl system.  (The binary
  825 distribution contains also a lot of additional modules, and the
  826 documentation in INF format.)
  827 
  828 What follows is a detailed guide through these steps.
  829 
  830 =head2 Prerequisites
  831 
  832 You need to have the latest EMX development environment, the full
  833 GNU tool suite (gawk renamed to awk, and GNU F<find.exe>
  834 earlier on path than the OS/2 F<find.exe>, same with F<sort.exe>, to
  835 check use
  836 
  837   find --version
  838   sort --version
  839 
  840 ). You need the latest version of F<pdksh> installed as F<sh.exe>.
  841 
  842 Check that you have B<BSD> libraries and headers installed, and - 
  843 optionally - Berkeley DB headers and libraries, and crypt.
  844 
  845 Possible locations to get the files:
  846 
  847 
  848   ftp://ftp.uni-heidelberg.de/pub/os2/unix/
  849   http://hobbes.nmsu.edu/h-browse.php?dir=/pub/os2
  850   http://cd.textfiles.com/hobbesos29804/disk1/DEV32/
  851   http://cd.textfiles.com/hobbesos29804/disk1/EMX09C/
  852 
  853 It is reported that the following archives contain enough utils to
  854 build perl: F<gnufutil.zip>, F<gnusutil.zip>, F<gnututil.zip>, F<gnused.zip>,
  855 F<gnupatch.zip>, F<gnuawk.zip>, F<gnumake.zip>, F<gnugrep.zip>, F<bsddev.zip> and
  856 F<ksh527rt.zip> (or a later version).  Note that all these utilities are
  857 known to be available from LEO:
  858 
  859   ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/
  860 
  861 Note also that the F<db.lib> and F<db.a> from the EMX distribution
  862 are not suitable for multi-threaded compile (even single-threaded
  863 flavor of Perl uses multi-threaded C RTL, for
  864 compatibility with XFree86-OS/2). Get a corrected one from
  865 
  866   http://www.ilyaz.org/software/os2/db_mt.zip
  867 
  868 If you have I<exactly the same version of Perl> installed already,
  869 make sure that no copies or perl are currently running.  Later steps
  870 of the build may fail since an older version of F<perl.dll> loaded into
  871 memory may be found.  Running C<make test> becomes meaningless, since
  872 the test are checking a previous build of perl (this situation is detected
  873 and reported by F<os2/os2_base.t> test).  Do not forget to unset
  874 C<PERL_EMXLOAD_SEC> in environment.
  875 
  876 Also make sure that you have F</tmp> directory on the current drive,
  877 and F<.> directory in your C<LIBPATH>. One may try to correct the
  878 latter condition by
  879 
  880   set BEGINLIBPATH .\.
  881 
  882 if you use something like F<CMD.EXE> or latest versions of
  883 F<4os2.exe>.  (Setting BEGINLIBPATH to just C<.> is ignored by the
  884 OS/2 kernel.)
  885 
  886 Make sure your gcc is good for C<-Zomf> linking: run C<omflibs>
  887 script in F</emx/lib> directory.
  888 
  889 Check that you have link386 installed. It comes standard with OS/2,
  890 but may be not installed due to customization. If typing
  891 
  892   link386
  893 
  894 shows you do not have it, do I<Selective install>, and choose C<Link
  895 object modules> in I<Optional system utilities/More>. If you get into
  896 link386 prompts, press C<Ctrl-C> to exit.
  897 
  898 =head2 Getting perl source
  899 
  900 You need to fetch the latest perl source (including developers
  901 releases). With some probability it is located in 
  902 
  903   http://www.cpan.org/src/
  904   http://www.cpan.org/src/unsupported
  905 
  906 If not, you may need to dig in the indices to find it in the directory
  907 of the current maintainer.
  908 
  909 Quick cycle of developers release may break the OS/2 build time to
  910 time, looking into 
  911 
  912   http://www.cpan.org/ports/os2/
  913 
  914 may indicate the latest release which was publicly released by the
  915 maintainer. Note that the release may include some additional patches
  916 to apply to the current source of perl.
  917 
  918 Extract it like this
  919 
  920   tar vzxf perl5.00409.tar.gz
  921 
  922 You may see a message about errors while extracting F<Configure>. This is
  923 because there is a conflict with a similarly-named file F<configure>.
  924 
  925 Change to the directory of extraction.
  926 
  927 =head2 Application of the patches
  928 
  929 You need to apply the patches in F<./os2/diff.*> like this:
  930 
  931   gnupatch -p0 < os2\diff.configure
  932 
  933 You may also need to apply the patches supplied with the binary
  934 distribution of perl.  It also makes sense to look on the
  935 perl5-porters mailing list for the latest OS/2-related patches (see
  936 L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/>).  Such
  937 patches usually contain strings C</os2/> and C<patch>, so it makes
  938 sense looking for these strings.
  939 
  940 =head2 Hand-editing
  941 
  942 You may look into the file F<./hints/os2.sh> and correct anything
  943 wrong you find there. I do not expect it is needed anywhere.
  944 
  945 =head2 Making
  946 
  947   sh Configure -des -D prefix=f:/perllib
  948 
  949 C<prefix> means: where to install the resulting perl library. Giving
  950 correct prefix you may avoid the need to specify C<PERLLIB_PREFIX>,
  951 see L</"C<PERLLIB_PREFIX>">.
  952 
  953 I<Ignore the message about missing C<ln>, and about C<-c> option to
  954 tr>. The latter is most probably already fixed, if you see it and can trace
  955 where the latter spurious warning comes from, please inform me.
  956 
  957 Now
  958 
  959   make
  960 
  961 At some moment the built may die, reporting a I<version mismatch> or
  962 I<unable to run F<perl>>.  This means that you do not have F<.> in
  963 your LIBPATH, so F<perl.exe> cannot find the needed F<perl67B2.dll> (treat
  964 these hex digits as line noise).  After this is fixed the build
  965 should finish without a lot of fuss.
  966 
  967 =head2 Testing
  968 
  969 Now run
  970 
  971   make test
  972 
  973 All tests should succeed (with some of them skipped).  If you have the
  974 same version of Perl installed, it is crucial that you have C<.> early
  975 in your LIBPATH (or in BEGINLIBPATH), otherwise your tests will most
  976 probably test the wrong version of Perl.
  977 
  978 Some tests may generate extra messages similar to
  979 
  980 =over 4
  981 
  982 =item A lot of C<bad free>
  983 
  984 in database tests related to Berkeley DB. I<This should be fixed already.>
  985 If it persists, you may disable this warnings, see L</"C<PERL_BADFREE>">.
  986 
  987 =item Process terminated by SIGTERM/SIGINT
  988 
  989 This is a standard message issued by OS/2 applications. *nix
  990 applications die in silence. It is considered to be a feature. One can
  991 easily disable this by appropriate sighandlers. 
  992 
  993 However the test engine bleeds these message to screen in unexpected
  994 moments. Two messages of this kind I<should> be present during
  995 testing.
  996 
  997 =back
  998 
  999 To get finer test reports, call
 1000 
 1001   perl t/harness
 1002 
 1003 The report with F<io/pipe.t> failing may look like this:
 1004 
 1005  Failed Test  Status Wstat Total Fail  Failed  List of failed
 1006  ------------------------------------------------------------
 1007  io/pipe.t                    12    1   8.33%  9
 1008  7 tests skipped, plus 56 subtests skipped.
 1009  Failed 1/195 test scripts, 99.49% okay. 1/6542 subtests failed,
 1010     99.98% okay.
 1011 
 1012 The reasons for most important skipped tests are:
 1013 
 1014 =over 8
 1015 
 1016 =item F<op/fs.t>
 1017 
 1018 =over 4
 1019 
 1020 =item Z<>18
 1021 
 1022 Checks C<atime> and C<mtime> of C<stat()> - unfortunately, HPFS
 1023 provides only 2sec time granularity (for compatibility with FAT?).
 1024 
 1025 =item Z<>25
 1026 
 1027 Checks C<truncate()> on a filehandle just opened for write - I do not
 1028 know why this should or should not work.
 1029 
 1030 =back
 1031 
 1032 =item F<op/stat.t>
 1033 
 1034 Checks C<stat()>. Tests:
 1035 
 1036 =over 4
 1037 
 1038 =item 4
 1039 
 1040 Checks C<atime> and C<mtime> of C<stat()> - unfortunately, HPFS
 1041 provides only 2sec time granularity (for compatibility with FAT?).
 1042 
 1043 =back
 1044 
 1045 =back
 1046 
 1047 =head2 Installing the built perl
 1048 
 1049 If you haven't yet moved C<perl*.dll> onto LIBPATH, do it now.
 1050 
 1051 Run
 1052 
 1053   make install
 1054 
 1055 It would put the generated files into needed locations. Manually put
 1056 F<perl.exe>, F<perl__.exe> and F<perl___.exe> to a location on your
 1057 PATH, F<perl.dll> to a location on your LIBPATH.
 1058 
 1059 Run
 1060 
 1061   make installcmd INSTALLCMDDIR=d:/ir/on/path
 1062 
 1063 to convert perl utilities to F<.cmd> files and put them on
 1064 PATH. You need to put F<.EXE>-utilities on path manually. They are
 1065 installed in C<$prefix/bin>, here C<$prefix> is what you gave to
 1066 F<Configure>, see L</Making>.
 1067 
 1068 If you use C<man>, either move the installed F<*/man/> directories to
 1069 your C<MANPATH>, or modify C<MANPATH> to match the location.  (One
 1070 could have avoided this by providing a correct C<manpath> option to
 1071 F<./Configure>, or editing F<./config.sh> between configuring and
 1072 making steps.)
 1073 
 1074 =head2 C<a.out>-style build
 1075 
 1076 Proceed as above, but make F<perl_.exe> (see L</"F<perl_.exe>">) by
 1077 
 1078   make perl_
 1079 
 1080 test and install by
 1081 
 1082   make aout_test
 1083   make aout_install
 1084 
 1085 Manually put F<perl_.exe> to a location on your PATH.
 1086 
 1087 B<Note.> The build process for C<perl_> I<does not know> about all the
 1088 dependencies, so you should make sure that anything is up-to-date,
 1089 say, by doing
 1090 
 1091   make perl_dll
 1092 
 1093 first.
 1094 
 1095 =head1 Building a binary distribution
 1096 
 1097 [This section provides a short overview only...]
 1098 
 1099 Building should proceed differently depending on whether the version of perl
 1100 you install is already present and used on your system, or is a new version
 1101 not yet used.  The description below assumes that the version is new, so
 1102 installing its DLLs and F<.pm> files will not disrupt the operation of your
 1103 system even if some intermediate steps are not yet fully working.
 1104 
 1105 The other cases require a little bit more convoluted procedures.  Below I
 1106 suppose that the current version of Perl is C<5.8.2>, so the executables are
 1107 named accordingly.
 1108 
 1109 =over
 1110 
 1111 =item 1.
 1112 
 1113 Fully build and test the Perl distribution.  Make sure that no tests are
 1114 failing with C<test> and C<aout_test> targets; fix the bugs in Perl and
 1115 the Perl test suite detected by these tests.  Make sure that C<all_test>
 1116 make target runs as clean as possible.  Check that F<os2/perlrexx.cmd>
 1117 runs fine.
 1118 
 1119 =item 2.
 1120 
 1121 Fully install Perl, including C<installcmd> target.  Copy the generated DLLs
 1122 to C<LIBPATH>; copy the numbered Perl executables (as in F<perl5.8.2.exe>)
 1123 to C<PATH>; copy C<perl_.exe> to C<PATH> as C<perl_5.8.2.exe>.  Think whether
 1124 you need backward-compatibility DLLs.  In most cases you do not need to install
 1125 them yet; but sometime this may simplify the following steps.
 1126 
 1127 =item 3.
 1128 
 1129 Make sure that C<CPAN.pm> can download files from CPAN.  If not, you may need
 1130 to manually install C<Net::FTP>.
 1131 
 1132 =item 4.
 1133 
 1134 Install the bundle C<Bundle::OS2_default>
 1135 
 1136  perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_1
 1137 
 1138 This may take a couple of hours on 1GHz processor (when run the first time).
 1139 And this should not be necessarily a smooth procedure.  Some modules may not
 1140 specify required dependencies, so one may need to repeat this procedure several
 1141 times until the results stabilize.
 1142 
 1143  perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_2
 1144  perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_3
 1145 
 1146 Even after they stabilize, some tests may fail.
 1147 
 1148 Fix as many discovered bugs as possible.  Document all the bugs which are not
 1149 fixed, and all the failures with unknown reasons.  Inspect the produced logs
 1150 F<00cpan_i_1> to find suspiciously skipped tests, and other fishy events.
 1151 
 1152 Keep in mind that I<installation> of some modules may fail too: for example,
 1153 the DLLs to update may be already loaded by F<CPAN.pm>.  Inspect the C<install>
 1154 logs (in the example above F<00cpan_i_1> etc) for errors, and install things
 1155 manually, as in
 1156 
 1157   cd $CPANHOME/.cpan/build/Digest-MD5-2.31
 1158   make install
 1159 
 1160 Some distributions may fail some tests, but you may want to install them
 1161 anyway (as above, or via C<force install> command of C<CPAN.pm> shell-mode).
 1162 
 1163 Since this procedure may take quite a long time to complete, it makes sense
 1164 to "freeze" your CPAN configuration by disabling periodic updates of the
 1165 local copy of CPAN index: set C<index_expire> to some big value (I use 365),
 1166 then save the settings
 1167 
 1168   CPAN> o conf index_expire 365
 1169   CPAN> o conf commit
 1170 
 1171 Reset back to the default value C<1> when you are finished.
 1172 
 1173 =item 5.
 1174 
 1175 When satisfied with the results, rerun the C<installcmd> target.  Now you
 1176 can copy C<perl5.8.2.exe> to C<perl.exe>, and install the other OMF-build
 1177 executables: C<perl__.exe> etc.  They are ready to be used.
 1178 
 1179 =item 6.
 1180 
 1181 Change to the C<./pod> directory of the build tree, download the Perl logo
 1182 F<CamelGrayBig.BMP>, and run
 1183 
 1184   ( perl2ipf > perl.ipf ) |& tee 00ipf
 1185   ipfc /INF perl.ipf |& tee 00inf
 1186 
 1187 This produces the Perl docs online book C<perl.INF>.  Install in on
 1188 C<BOOKSHELF> path.
 1189 
 1190 =item 7.
 1191 
 1192 Now is the time to build statically linked executable F<perl_.exe> which
 1193 includes newly-installed via C<Bundle::OS2_default> modules.  Doing testing
 1194 via C<CPAN.pm> is going to be painfully slow, since it statically links
 1195 a new executable per XS extension.
 1196 
 1197 Here is a possible workaround: create a toplevel F<Makefile.PL> in
 1198 F<$CPANHOME/.cpan/build/> with contents being (compare with L</Making
 1199 executables with a custom collection of statically loaded extensions>)
 1200 
 1201   use ExtUtils::MakeMaker;
 1202   WriteMakefile NAME => 'dummy';
 1203 
 1204 execute this as
 1205 
 1206   perl_5.8.2.exe Makefile.PL <nul |& tee 00aout_c1
 1207   make -k all test <nul |& 00aout_t1
 1208 
 1209 Again, this procedure should not be absolutely smooth.  Some C<Makefile.PL>'s
 1210 in subdirectories may be buggy, and would not run as "child" scripts.  The
 1211 interdependency of modules can strike you; however, since non-XS modules
 1212 are already installed, the prerequisites of most modules have a very good
 1213 chance to be present.
 1214 
 1215 If you discover some glitches, move directories of problematic modules to a
 1216 different location; if these modules are non-XS modules, you may just ignore
 1217 them - they are already installed; the remaining, XS, modules you need to
 1218 install manually one by one.
 1219 
 1220 After each such removal you need to rerun the C<Makefile.PL>/C<make> process;
 1221 usually this procedure converges soon.  (But be sure to convert all the
 1222 necessary external C libraries from F<.lib> format to F<.a> format: run one of
 1223 
 1224   emxaout foo.lib
 1225   emximp -o foo.a foo.lib
 1226 
 1227 whichever is appropriate.)  Also, make sure that the DLLs for external
 1228 libraries are usable with with executables compiled without C<-Zmtd> options.
 1229 
 1230 When you are sure that only a few subdirectories
 1231 lead to failures, you may want to add C<-j4> option to C<make> to speed up
 1232 skipping subdirectories with already finished build.
 1233 
 1234 When you are satisfied with the results of tests, install the build C libraries
 1235 for extensions:
 1236 
 1237   make install |& tee 00aout_i
 1238 
 1239 Now you can rename the file F<./perl.exe> generated during the last phase
 1240 to F<perl_5.8.2.exe>; place it on C<PATH>; if there is an inter-dependency
 1241 between some XS modules, you may need to repeat the C<test>/C<install> loop
 1242 with this new executable and some excluded modules - until the procedure
 1243 converges.
 1244 
 1245 Now you have all the necessary F<.a> libraries for these Perl modules in the
 1246 places where Perl builder can find it.  Use the perl builder: change to an
 1247 empty directory, create a "dummy" F<Makefile.PL> again, and run
 1248 
 1249   perl_5.8.2.exe Makefile.PL |& tee 00c
 1250   make perl		     |& tee 00p
 1251 
 1252 This should create an executable F<./perl.exe> with all the statically loaded
 1253 extensions built in.  Compare the generated F<perlmain.c> files to make sure
 1254 that during the iterations the number of loaded extensions only increases.
 1255 Rename F<./perl.exe> to F<perl_5.8.2.exe> on C<PATH>.
 1256 
 1257 When it converges, you got a functional variant of F<perl_5.8.2.exe>; copy it
 1258 to C<perl_.exe>.  You are done with generation of the local Perl installation.
 1259 
 1260 =item 8.
 1261 
 1262 Make sure that the installed modules are actually installed in the location
 1263 of the new Perl, and are not inherited from entries of @INC given for
 1264 inheritance from the older versions of Perl: set C<PERLLIB_582_PREFIX> to
 1265 redirect the new version of Perl to a new location, and copy the installed
 1266 files to this new location.  Redo the tests to make sure that the versions of
 1267 modules inherited from older versions of Perl are not needed.
 1268 
 1269 Actually, the log output of L<pod2ipf(1)> during the step 6 gives a very detailed
 1270 info about which modules are loaded from which place; so you may use it as
 1271 an additional verification tool.
 1272 
 1273 Check that some temporary files did not make into the perl install tree.
 1274 Run something like this
 1275 
 1276   pfind . -f "!(/\.(pm|pl|ix|al|h|a|lib|txt|pod|imp|bs|dll|ld|bs|inc|xbm|yml|cgi|uu|e2x|skip|packlist|eg|cfg|html|pub|enc|all|ini|po|pot)$/i or /^\w+$/") | less
 1277 
 1278 in the install tree (both top one and F<sitelib> one).
 1279 
 1280 Compress all the DLLs with F<lxlite>.  The tiny F<.exe> can be compressed with
 1281 C</c:max> (the bug only appears when there is a fixup in the last 6 bytes of a
 1282 page (?); since the tiny executables are much smaller than a page, the bug
 1283 will not hit).  Do not compress C<perl_.exe> - it would not work under DOS.
 1284 
 1285 =item 9.
 1286 
 1287 Now you can generate the binary distribution.  This is done by running the
 1288 test of the CPAN distribution C<OS2::SoftInstaller>.  Tune up the file
 1289 F<test.pl> to suit the layout of current version of Perl first.  Do not
 1290 forget to pack the necessary external DLLs accordingly.  Include the
 1291 description of the bugs and test suite failures you could not fix.  Include
 1292 the small-stack versions of Perl executables from Perl build directory.
 1293 
 1294 Include F<perl5.def> so that people can relink the perl DLL preserving
 1295 the binary compatibility, or can create compatibility DLLs.  Include the diff
 1296 files (C<diff -pu old new>) of fixes you did so that people can rebuild your
 1297 version.  Include F<perl5.map> so that one can use remote debugging.
 1298 
 1299 =item 10.
 1300 
 1301 Share what you did with the other people.  Relax.  Enjoy fruits of your work.
 1302 
 1303 =item 11.
 1304 
 1305 Brace yourself for thanks, bug reports, hate mail and spam coming as result
 1306 of the previous step.  No good deed should remain unpunished!
 1307 
 1308 =back
 1309 
 1310 =head1 Building custom F<.EXE> files
 1311 
 1312 The Perl executables can be easily rebuilt at any moment.  Moreover, one can
 1313 use the I<embedding> interface (see L<perlembed>) to make very customized
 1314 executables.
 1315 
 1316 =head2 Making executables with a custom collection of statically loaded extensions
 1317 
 1318 It is a little bit easier to do so while I<decreasing> the list of statically
 1319 loaded extensions.  We discuss this case only here.
 1320 
 1321 =over
 1322 
 1323 =item 1.
 1324 
 1325 Change to an empty directory, and create a placeholder <Makefile.PL>:
 1326 
 1327   use ExtUtils::MakeMaker;
 1328   WriteMakefile NAME => 'dummy';
 1329 
 1330 =item 2.
 1331 
 1332 Run it with the flavor of Perl (F<perl.exe> or F<perl_.exe>) you want to
 1333 rebuild.
 1334 
 1335   perl_ Makefile.PL
 1336 
 1337 =item 3.
 1338 
 1339 Ask it to create new Perl executable:
 1340 
 1341   make perl
 1342 
 1343 (you may need to manually add C<PERLTYPE=-DPERL_CORE> to this commandline on
 1344 some versions of Perl; the symptom is that the command-line globbing does not
 1345 work from OS/2 shells with the newly-compiled executable; check with
 1346 
 1347   .\perl.exe -wle "print for @ARGV" *
 1348 
 1349 ).
 1350 
 1351 =item 4.
 1352 
 1353 The previous step created F<perlmain.c> which contains a list of newXS() calls
 1354 near the end.  Removing unnecessary calls, and rerunning
 1355 
 1356   make perl
 1357 
 1358 will produce a customized executable.
 1359 
 1360 =back
 1361 
 1362 =head2 Making executables with a custom search-paths
 1363 
 1364 The default perl executable is flexible enough to support most usages.
 1365 However, one may want something yet more flexible; for example, one may want
 1366 to find Perl DLL relatively to the location of the EXE file; or one may want
 1367 to ignore the environment when setting the Perl-library search patch, etc.
 1368 
 1369 If you fill comfortable with I<embedding> interface (see L<perlembed>), such
 1370 things are easy to do repeating the steps outlined in L/<Making
 1371 executables with a custom collection of statically loaded extensions>, and
 1372 doing more comprehensive edits to main() of F<perlmain.c>.  The people with
 1373 little desire to understand Perl can just rename main(), and do necessary
 1374 modification in a custom main() which calls the renamed function in appropriate
 1375 time.
 1376 
 1377 However, there is a third way: perl DLL exports the main() function and several
 1378 callbacks to customize the search path.  Below is a complete example of a
 1379 "Perl loader" which
 1380 
 1381 =over
 1382 
 1383 =item 1.
 1384 
 1385 Looks for Perl DLL in the directory C<$exedir/../dll>;
 1386 
 1387 =item 2.
 1388 
 1389 Prepends the above directory to C<BEGINLIBPATH>;
 1390 
 1391 =item 3.
 1392 
 1393 Fails if the Perl DLL found via C<BEGINLIBPATH> is different from what was
 1394 loaded on step 1; e.g., another process could have loaded it from C<LIBPATH>
 1395 or from a different value of C<BEGINLIBPATH>.  In these cases one needs to
 1396 modify the setting of the system so that this other process either does not
 1397 run, or loads the DLL from C<BEGINLIBPATH> with C<LIBPATHSTRICT=T> (available
 1398 with kernels after September 2000).
 1399 
 1400 =item 4.
 1401 
 1402 Loads Perl library from C<$exedir/../dll/lib/>.
 1403 
 1404 =item 5.
 1405 
 1406 Uses Bourne shell from C<$exedir/../dll/sh/ksh.exe>.
 1407 
 1408 =back
 1409 
 1410 For best results compile the C file below with the same options as the Perl
 1411 DLL.  However, a lot of functionality will work even if the executable is not
 1412 an EMX applications, e.g., if compiled with
 1413 
 1414   gcc -Wall -DDOSISH -DOS2=1 -O2 -s -Zomf -Zsys perl-starter.c \
 1415     -DPERL_DLL_BASENAME=\"perl312F\" -Zstack 8192 -Zlinker /PM:VIO
 1416 
 1417 Here is the sample C file:
 1418 
 1419  #define INCL_DOS
 1420  #define INCL_NOPM
 1421  /* These are needed for compile if os2.h includes os2tk.h, not
 1422   * os2emx.h */
 1423  #define INCL_DOSPROCESS
 1424  #include <os2.h>
 1425 
 1426  #include "EXTERN.h"
 1427  #define PERL_IN_MINIPERLMAIN_C
 1428  #include "perl.h"
 1429 
 1430  static char *me;
 1431  HMODULE handle;
 1432 
 1433  static void
 1434  die_with(char *msg1, char *msg2, char *msg3, char *msg4)
 1435  {
 1436     ULONG c;
 1437     char *s = " error: ";
 1438 
 1439     DosWrite(2, me, strlen(me), &c);
 1440     DosWrite(2, s, strlen(s), &c);
 1441     DosWrite(2, msg1, strlen(msg1), &c);
 1442     DosWrite(2, msg2, strlen(msg2), &c);
 1443     DosWrite(2, msg3, strlen(msg3), &c);
 1444     DosWrite(2, msg4, strlen(msg4), &c);
 1445     DosWrite(2, "\r\n", 2, &c);
 1446     exit(255);
 1447  }
 1448 
 1449  typedef ULONG (*fill_extLibpath_t)(int type,
 1450                                     char *pre,
 1451                                     char *post,
 1452                                     int replace,
 1453                                     char *msg);
 1454  typedef int (*main_t)(int type, char *argv[], char *env[]);
 1455  typedef int (*handler_t)(void* data, int which);
 1456 
 1457  #ifndef PERL_DLL_BASENAME
 1458  #  define PERL_DLL_BASENAME "perl"
 1459  #endif
 1460 
 1461  static HMODULE
 1462  load_perl_dll(char *basename)
 1463  {
 1464      char buf[300], fail[260];
 1465      STRLEN l, dirl;
 1466      fill_extLibpath_t f;
 1467      ULONG rc_fullname;
 1468      HMODULE handle, handle1;
 1469 
 1470      if (_execname(buf, sizeof(buf) - 13) != 0)
 1471          die_with("Can't find full path: ", strerror(errno), "", "");
 1472      /* XXXX Fill 'me' with new value */
 1473      l = strlen(buf);
 1474      while (l && buf[l-1] != '/' && buf[l-1] != '\\')
 1475          l--;
 1476      dirl = l - 1;
 1477      strcpy(buf + l, basename);
 1478      l += strlen(basename);
 1479      strcpy(buf + l, ".dll");
 1480      if ( (rc_fullname = DosLoadModule(fail, sizeof fail, buf, &handle))
 1481                                                                     != 0
 1482           && DosLoadModule(fail, sizeof fail, basename, &handle) != 0 )
 1483          die_with("Can't load DLL ", buf, "", "");
 1484      if (rc_fullname)
 1485          return handle;    /* was loaded with short name; all is fine */
 1486      if (DosQueryProcAddr(handle, 0, "fill_extLibpath", (PFN*)&f))
 1487          die_with(buf,
 1488                   ": DLL exports no symbol ",
 1489                   "fill_extLibpath",
 1490                   "");
 1491      buf[dirl] = 0;
 1492      if (f(0 /*BEGINLIBPATH*/, buf /* prepend */, NULL /* append */,
 1493            0 /* keep old value */, me))
 1494          die_with(me, ": prepending BEGINLIBPATH", "", "");
 1495      if (DosLoadModule(fail, sizeof fail, basename, &handle1) != 0)
 1496          die_with(me,
 1497                   ": finding perl DLL again via BEGINLIBPATH",
 1498                   "",
 1499                   "");
 1500      buf[dirl] = '\\';
 1501      if (handle1 != handle) {
 1502          if (DosQueryModuleName(handle1, sizeof(fail), fail))
 1503              strcpy(fail, "???");
 1504          die_with(buf,
 1505                   ":\n\tperl DLL via BEGINLIBPATH is different: \n\t",
 1506                   fail,
 1507                   "\n\tYou may need to manipulate global BEGINLIBPATH"
 1508                      " and LIBPATHSTRICT"
 1509                      "\n\tso that the other copy is loaded via"
 1510                      BEGINLIBPATH.");
 1511      }
 1512      return handle;
 1513  }
 1514 
 1515  int
 1516  main(int argc, char **argv, char **env)
 1517  {
 1518      main_t f;
 1519      handler_t h;
 1520 
 1521      me = argv[0];
 1522      /**/
 1523      handle = load_perl_dll(PERL_DLL_BASENAME);
 1524 
 1525      if (DosQueryProcAddr(handle,
 1526                           0,
 1527                           "Perl_OS2_handler_install",
 1528                           (PFN*)&h))
 1529          die_with(PERL_DLL_BASENAME,
 1530                   ": DLL exports no symbol ",
 1531                   "Perl_OS2_handler_install",
 1532                   "");
 1533      if ( !h((void *)"~installprefix", Perlos2_handler_perllib_from)
 1534           || !h((void *)"~dll", Perlos2_handler_perllib_to)
 1535           || !h((void *)"~dll/sh/ksh.exe", Perlos2_handler_perl_sh) )
 1536          die_with(PERL_DLL_BASENAME,
 1537                   ": Can't install @INC manglers",
 1538                   "",
 1539                   "");
 1540      if (DosQueryProcAddr(handle, 0, "dll_perlmain", (PFN*)&f))
 1541          die_with(PERL_DLL_BASENAME,
 1542                   ": DLL exports no symbol ",
 1543                   "dll_perlmain",
 1544                   "");
 1545      return f(argc, argv, env);
 1546  }
 1547 
 1548 =head1 Build FAQ
 1549 
 1550 =head2 Some C</> became C<\> in pdksh.
 1551 
 1552 You have a very old pdksh. See L</Prerequisites>.
 1553 
 1554 =head2 C<'errno'> - unresolved external
 1555 
 1556 You do not have MT-safe F<db.lib>. See L</Prerequisites>.
 1557 
 1558 =head2 Problems with tr or sed
 1559 
 1560 reported with very old version of tr and sed.
 1561 
 1562 =head2 Some problem (forget which ;-)
 1563 
 1564 You have an older version of F<perl.dll> on your LIBPATH, which
 1565 broke the build of extensions.
 1566 
 1567 =head2 Library ... not found
 1568 
 1569 You did not run C<omflibs>. See L</Prerequisites>.
 1570 
 1571 =head2 Segfault in make
 1572 
 1573 You use an old version of GNU make. See L</Prerequisites>.
 1574 
 1575 =head2 op/sprintf test failure
 1576 
 1577 This can result from a bug in emx sprintf which was fixed in 0.9d fix 03.
 1578 
 1579 =head1 Specific (mis)features of OS/2 port
 1580 
 1581 =head2 C<setpriority>, C<getpriority>
 1582 
 1583 Note that these functions are compatible with *nix, not with the older
 1584 ports of '94 - 95. The priorities are absolute, go from 32 to -95,
 1585 lower is quicker. 0 is the default priority.
 1586 
 1587 B<WARNING>.  Calling C<getpriority> on a non-existing process could lock
 1588 the system before Warp3 fixpak22.  Starting with Warp3, Perl will use
 1589 a workaround: it aborts getpriority() if the process is not present.
 1590 This is not possible on older versions C<2.*>, and has a race
 1591 condition anyway.
 1592 
 1593 =head2 C<system()>
 1594 
 1595 Multi-argument form of C<system()> allows an additional numeric
 1596 argument. The meaning of this argument is described in
 1597 L<OS2::Process>.
 1598 
 1599 When finding a program to run, Perl first asks the OS to look for executables
 1600 on C<PATH> (OS/2 adds extension F<.exe> if no extension is present).
 1601 If not found, it looks for a script with possible extensions 
 1602 added in this order: no extension, F<.cmd>, F<.btm>, 
 1603 F<.bat>, F<.pl>.  If found, Perl checks the start of the file for magic
 1604 strings C<"#!"> and C<"extproc ">.  If found, Perl uses the rest of the
 1605 first line as the beginning of the command line to run this script.  The
 1606 only mangling done to the first line is extraction of arguments (currently
 1607 up to 3), and ignoring of the path-part of the "interpreter" name if it can't
 1608 be found using the full path.
 1609 
 1610 E.g., C<system 'foo', 'bar', 'baz'> may lead Perl to finding
 1611 F<C:/emx/bin/foo.cmd> with the first line being
 1612 
 1613  extproc /bin/bash    -x   -c
 1614 
 1615 If F</bin/bash.exe> is not found, then Perl looks for an executable F<bash.exe> on
 1616 C<PATH>.  If found in F<C:/emx.add/bin/bash.exe>, then the above system() is
 1617 translated to
 1618 
 1619   system qw(C:/emx.add/bin/bash.exe -x -c C:/emx/bin/foo.cmd bar baz)
 1620 
 1621 One additional translation is performed: instead of F</bin/sh> Perl uses
 1622 the hardwired-or-customized shell (see L</"C<PERL_SH_DIR>">).
 1623 
 1624 The above search for "interpreter" is recursive: if F<bash> executable is not
 1625 found, but F<bash.btm> is found, Perl will investigate its first line etc.
 1626 The only hardwired limit on the recursion depth is implicit: there is a limit
 1627 4 on the number of additional arguments inserted before the actual arguments
 1628 given to system().  In particular, if no additional arguments are specified
 1629 on the "magic" first lines, then the limit on the depth is 4.
 1630 
 1631 If Perl finds that the found executable is of PM type when the
 1632 current session is not, it will start the new process in a separate session of
 1633 necessary type.  Call via C<OS2::Process> to disable this magic.
 1634 
 1635 B<WARNING>.  Due to the described logic, you need to explicitly
 1636 specify F<.com> extension if needed.  Moreover, if the executable
 1637 F<perl5.6.1> is requested, Perl will not look for F<perl5.6.1.exe>.
 1638 [This may change in the future.]
 1639 
 1640 =head2 C<extproc> on the first line
 1641 
 1642 If the first chars of a Perl script are C<"extproc ">, this line is treated
 1643 as C<#!>-line, thus all the switches on this line are processed (twice
 1644 if script was started via cmd.exe).  See L<perlrun/DESCRIPTION>.
 1645 
 1646 =head2 Additional modules:
 1647 
 1648 L<OS2::Process>, L<OS2::DLL>, L<OS2::REXX>, L<OS2::PrfDB>, L<OS2::ExtAttr>. These
 1649 modules provide access to additional numeric argument for C<system>
 1650 and to the information about the running process,
 1651 to DLLs having functions with REXX signature and to the REXX runtime, to
 1652 OS/2 databases in the F<.INI> format, and to Extended Attributes.
 1653 
 1654 Two additional extensions by Andreas Kaiser, C<OS2::UPM>, and
 1655 C<OS2::FTP>, are included into C<ILYAZ> directory, mirrored on CPAN.
 1656 Other OS/2-related extensions are available too.
 1657 
 1658 =head2 Prebuilt methods:
 1659 
 1660 =over 4
 1661 
 1662 =item C<File::Copy::syscopy>
 1663 
 1664 used by C<File::Copy::copy>, see L<File::Copy>.
 1665 
 1666 =item C<DynaLoader::mod2fname>
 1667 
 1668 used by C<DynaLoader> for DLL name mangling.
 1669 
 1670 =item  C<Cwd::current_drive()>
 1671 
 1672 Self explanatory.
 1673 
 1674 =item  C<Cwd::sys_chdir(name)>
 1675 
 1676 leaves drive as it is.
 1677 
 1678 =item  C<Cwd::change_drive(name)>
 1679 
 1680 changes the "current" drive.
 1681 
 1682 =item  C<Cwd::sys_is_absolute(name)>
 1683 
 1684 means has drive letter and is_rooted.
 1685 
 1686 =item  C<Cwd::sys_is_rooted(name)>
 1687 
 1688 means has leading C<[/\\]> (maybe after a drive-letter:).
 1689 
 1690 =item  C<Cwd::sys_is_relative(name)>
 1691 
 1692 means changes with current dir.
 1693 
 1694 =item  C<Cwd::sys_cwd(name)>
 1695 
 1696 Interface to cwd from EMX. Used by C<Cwd::cwd>.
 1697 
 1698 =item  C<Cwd::sys_abspath(name, dir)>
 1699 
 1700 Really really odious function to implement. Returns absolute name of
 1701 file which would have C<name> if CWD were C<dir>.  C<Dir> defaults to the
 1702 current dir.
 1703 
 1704 =item  C<Cwd::extLibpath([type])>
 1705 
 1706 Get current value of extended library search path. If C<type> is
 1707 present and positive, works with C<END_LIBPATH>, if negative, works
 1708 with C<LIBPATHSTRICT>, otherwise with C<BEGIN_LIBPATH>. 
 1709 
 1710 =item  C<Cwd::extLibpath_set( path [, type ] )>
 1711 
 1712 Set current value of extended library search path. If C<type> is
 1713 present and positive, works with <END_LIBPATH>, if negative, works
 1714 with C<LIBPATHSTRICT>, otherwise with C<BEGIN_LIBPATH>.
 1715 
 1716 =item C<OS2::Error(do_harderror,do_exception)>
 1717 
 1718 Returns	C<undef> if it was not called yet, otherwise bit 1 is
 1719 set if on the previous call do_harderror was enabled, bit
 1720 2 is set if on previous call do_exception was enabled.
 1721 
 1722 This function enables/disables error popups associated with 
 1723 hardware errors (Disk not ready etc.) and software exceptions.
 1724 
 1725 I know of no way to find out the state of popups I<before> the first call
 1726 to this function.
 1727 
 1728 =item C<OS2::Errors2Drive(drive)>
 1729 
 1730 Returns C<undef> if it was not called yet, otherwise return false if errors
 1731 were not requested to be written to a hard drive, or the drive letter if
 1732 this was requested.
 1733 
 1734 This function may redirect error popups associated with hardware errors
 1735 (Disk not ready etc.) and software exceptions to the file POPUPLOG.OS2 at
 1736 the root directory of the specified drive.  Overrides OS2::Error() specified
 1737 by individual programs.  Given argument undef will disable redirection.
 1738 
 1739 Has global effect, persists after the application exits.
 1740 
 1741 I know of no way to find out the state of redirection of popups to the disk
 1742 I<before> the first call to this function.
 1743 
 1744 =item OS2::SysInfo()
 1745 
 1746 Returns a hash with system information. The keys of the hash are
 1747 
 1748 	MAX_PATH_LENGTH, MAX_TEXT_SESSIONS, MAX_PM_SESSIONS,
 1749 	MAX_VDM_SESSIONS, BOOT_DRIVE, DYN_PRI_VARIATION,
 1750 	MAX_WAIT, MIN_SLICE, MAX_SLICE, PAGE_SIZE,
 1751 	VERSION_MAJOR, VERSION_MINOR, VERSION_REVISION,
 1752 	MS_COUNT, TIME_LOW, TIME_HIGH, TOTPHYSMEM, TOTRESMEM,
 1753 	TOTAVAILMEM, MAXPRMEM, MAXSHMEM, TIMER_INTERVAL,
 1754 	MAX_COMP_LENGTH, FOREGROUND_FS_SESSION,
 1755 	FOREGROUND_PROCESS
 1756 
 1757 =item OS2::BootDrive()
 1758 
 1759 Returns a letter without colon.
 1760 
 1761 =item C<OS2::MorphPM(serve)>, C<OS2::UnMorphPM(serve)>
 1762 
 1763 Transforms the current application into a PM application and back.
 1764 The argument true means that a real message loop is going to be served.
 1765 OS2::MorphPM() returns the PM message queue handle as an integer.
 1766 
 1767 See L</"Centralized management of resources"> for additional details.
 1768 
 1769 =item C<OS2::Serve_Messages(force)>
 1770 
 1771 Fake on-demand retrieval of outstanding PM messages.  If C<force> is false,
 1772 will not dispatch messages if a real message loop is known to
 1773 be present.  Returns number of messages retrieved.
 1774 
 1775 Dies with "QUITing..." if WM_QUIT message is obtained.
 1776 
 1777 =item C<OS2::Process_Messages(force [, cnt])>
 1778 
 1779 Retrieval of PM messages until window creation/destruction.  
 1780 If C<force> is false, will not dispatch messages if a real message loop
 1781 is known to be present.
 1782 
 1783 Returns change in number of windows.  If C<cnt> is given,
 1784 it is incremented by the number of messages retrieved.
 1785 
 1786 Dies with "QUITing..." if WM_QUIT message is obtained.
 1787 
 1788 =item C<OS2::_control87(new,mask)>
 1789 
 1790 the same as L<_control87(3)> of EMX.  Takes integers as arguments, returns
 1791 the previous coprocessor control word as an integer.  Only bits in C<new> which
 1792 are present in C<mask> are changed in the control word.
 1793 
 1794 =item OS2::get_control87()
 1795 
 1796 gets the coprocessor control word as an integer.
 1797 
 1798 =item C<OS2::set_control87_em(new=MCW_EM,mask=MCW_EM)>
 1799 
 1800 The variant of OS2::_control87() with default values good for
 1801 handling exception mask: if no C<mask>, uses exception mask part of C<new>
 1802 only.  If no C<new>, disables all the floating point exceptions.
 1803 
 1804 See L</"Misfeatures"> for details.
 1805 
 1806 =item C<OS2::DLLname([how [, \&xsub]])>
 1807 
 1808 Gives the information about the Perl DLL or the DLL containing the C
 1809 function bound to by C<&xsub>.  The meaning of C<how> is: default (2):
 1810 full name; 0: handle; 1: module name.
 1811 
 1812 =back
 1813 
 1814 (Note that some of these may be moved to different libraries -
 1815 eventually).
 1816 
 1817 
 1818 =head2 Prebuilt variables:
 1819 
 1820 =over 4
 1821 
 1822 =item $OS2::emx_rev
 1823 
 1824 numeric value is the same as _emx_rev of EMX, a string value the same
 1825 as _emx_vprt (similar to C<0.9c>).
 1826 
 1827 =item $OS2::emx_env
 1828 
 1829 same as _emx_env of EMX, a number similar to 0x8001.
 1830 
 1831 =item $OS2::os_ver
 1832 
 1833 a number C<OS_MAJOR + 0.001 * OS_MINOR>.
 1834 
 1835 =item $OS2::is_aout
 1836 
 1837 true if the Perl library was compiled in AOUT format.
 1838 
 1839 =item $OS2::can_fork
 1840 
 1841 true if the current executable is an AOUT EMX executable, so Perl can
 1842 fork.  Do not use this, use the portable check for
 1843 $Config::Config{dfork}.
 1844 
 1845 =item $OS2::nsyserror
 1846 
 1847 This variable (default is 1) controls whether to enforce the contents
 1848 of $^E to start with C<SYS0003>-like id.  If set to 0, then the string
 1849 value of $^E is what is available from the OS/2 message file.  (Some
 1850 messages in this file have an C<SYS0003>-like id prepended, some not.)
 1851 
 1852 =back
 1853 
 1854 =head2 Misfeatures
 1855 
 1856 =over 4
 1857 
 1858 =item *
 1859 
 1860 Since L<flock(3)> is present in EMX, but is not functional, it is 
 1861 emulated by perl.  To disable the emulations, set environment variable
 1862 C<USE_PERL_FLOCK=0>.
 1863 
 1864 =item *
 1865 
 1866 Here is the list of things which may be "broken" on
 1867 EMX (from EMX docs):
 1868 
 1869 =over 4
 1870 
 1871 =item *
 1872 
 1873 The functions L<recvmsg(3)>, L<sendmsg(3)>, and L<socketpair(3)> are not
 1874 implemented.
 1875 
 1876 =item *
 1877 
 1878 L<sock_init(3)> is not required and not implemented.
 1879 
 1880 =item *
 1881 
 1882 L<flock(3)> is not yet implemented (dummy function).  (Perl has a workaround.)
 1883 
 1884 =item *
 1885 
 1886 L<kill(3)>:  Special treatment of PID=0, PID=1 and PID=-1 is not implemented.
 1887 
 1888 =item *
 1889 
 1890 L<waitpid(3)>:
 1891 
 1892       WUNTRACED
 1893 	      Not implemented.
 1894       waitpid() is not implemented for negative values of PID.
 1895 
 1896 =back
 1897 
 1898 Note that C<kill -9> does not work with the current version of EMX.
 1899 
 1900 =item *
 1901 
 1902 See L</"Text-mode filehandles">.
 1903 
 1904 =item *
 1905 
 1906 Unix-domain sockets on OS/2 live in a pseudo-file-system C</sockets/...>.
 1907 To avoid a failure to create a socket with a name of a different form,
 1908 C<"/socket/"> is prepended to the socket name (unless it starts with this
 1909 already).
 1910 
 1911 This may lead to problems later in case the socket is accessed via the
 1912 "usual" file-system calls using the "initial" name.
 1913 
 1914 =item *
 1915 
 1916 Apparently, IBM used a compiler (for some period of time around '95?) which
 1917 changes FP mask right and left.  This is not I<that> bad for IBM's
 1918 programs, but the same compiler was used for DLLs which are used with
 1919 general-purpose applications.  When these DLLs are used, the state of
 1920 floating-point flags in the application is not predictable.
 1921 
 1922 What is much worse, some DLLs change the floating point flags when in
 1923 _DLLInitTerm() (e.g., F<TCP32IP>).  This means that even if you do not I<call>
 1924 any function in the DLL, just the act of loading this DLL will reset your
 1925 flags.  What is worse, the same compiler was used to compile some HOOK DLLs.
 1926 Given that HOOK dlls are executed in the context of I<all> the applications
 1927 in the system, this means a complete unpredictability of floating point
 1928 flags on systems using such HOOK DLLs.  E.g., F<GAMESRVR.DLL> of B<DIVE>
 1929 origin changes the floating point flags on each write to the TTY of a VIO
 1930 (windowed text-mode) applications.
 1931 
 1932 Some other (not completely debugged) situations when FP flags change include
 1933 some video drivers (?), and some operations related to creation of the windows.
 1934 People who code B<OpenGL> may have more experience on this.
 1935 
 1936 Perl is generally used in the situation when all the floating-point
 1937 exceptions are ignored, as is the default under EMX.  If they are not ignored,
 1938 some benign Perl programs would get a C<SIGFPE> and would die a horrible death.
 1939 
 1940 To circumvent this, Perl uses two hacks.  They help against I<one> type of
 1941 damage only: FP flags changed when loading a DLL.
 1942 
 1943 One of the hacks is to disable floating point exceptions on Perl startup (as
 1944 is the default with EMX).  This helps only with compile-time-linked DLLs
 1945 changing the flags before main() had a chance to be called.
 1946 
 1947 The other hack is to restore FP flags after a call to dlopen().  This helps
 1948 against similar damage done by DLLs _DLLInitTerm() at runtime.  Currently
 1949 no way to switch these hacks off is provided.
 1950 
 1951 =back
 1952 
 1953 =head2 Modifications
 1954 
 1955 Perl modifies some standard C library calls in the following ways:
 1956 
 1957 =over 9
 1958 
 1959 =item C<popen>
 1960 
 1961 C<my_popen> uses F<sh.exe> if shell is required, cf. L</"C<PERL_SH_DIR>">.
 1962 
 1963 =item C<tmpnam>
 1964 
 1965 is created using C<TMP> or C<TEMP> environment variable, via
 1966 C<tempnam>.
 1967 
 1968 =item C<tmpfile>
 1969 
 1970 If the current directory is not writable, file is created using modified
 1971 C<tmpnam>, so there may be a race condition.
 1972 
 1973 =item C<ctermid>
 1974 
 1975 a dummy implementation.
 1976 
 1977 =item C<stat>
 1978 
 1979 C<os2_stat> special-cases F</dev/tty> and F</dev/con>.
 1980 
 1981 =item C<mkdir>, C<rmdir>
 1982 
 1983 these EMX functions do not work if the path contains a trailing C</>.
 1984 Perl contains a workaround for this.
 1985 
 1986 =item C<flock>
 1987 
 1988 Since L<flock(3)> is present in EMX, but is not functional, it is 
 1989 emulated by perl.  To disable the emulations, set environment variable
 1990 C<USE_PERL_FLOCK=0>.
 1991 
 1992 =back
 1993 
 1994 =head2 Identifying DLLs
 1995 
 1996 All the DLLs built with the current versions of Perl have ID strings
 1997 identifying the name of the extension, its version, and the version
 1998 of Perl required for this DLL.  Run C<bldlevel DLL-name> to find this
 1999 info.
 2000 
 2001 =head2 Centralized management of resources
 2002 
 2003 Since to call certain OS/2 API one needs to have a correctly initialized
 2004 C<Win> subsystem, OS/2-specific extensions may require getting C<HAB>s and
 2005 C<HMQ>s.  If an extension would do it on its own, another extension could
 2006 fail to initialize.
 2007 
 2008 Perl provides a centralized management of these resources:
 2009 
 2010 =over
 2011 
 2012 =item C<HAB>
 2013 
 2014 To get the HAB, the extension should call C<hab = perl_hab_GET()> in C.  After
 2015 this call is performed, C<hab> may be accessed as C<Perl_hab>.  There is
 2016 no need to release the HAB after it is used.
 2017 
 2018 If by some reasons F<perl.h> cannot be included, use
 2019 
 2020   extern int Perl_hab_GET(void);
 2021 
 2022 instead.
 2023 
 2024 =item C<HMQ>
 2025 
 2026 There are two cases:
 2027 
 2028 =over
 2029 
 2030 =item *
 2031 
 2032 the extension needs an C<HMQ> only because some API will not work otherwise.
 2033 Use C<serve = 0> below.
 2034 
 2035 =item *
 2036 
 2037 the extension needs an C<HMQ> since it wants to engage in a PM event loop.
 2038 Use C<serve = 1> below.
 2039 
 2040 =back
 2041 
 2042 To get an C<HMQ>, the extension should call C<hmq = perl_hmq_GET(serve)> in C.
 2043 After this call is performed, C<hmq> may be accessed as C<Perl_hmq>.
 2044 
 2045 To signal to Perl that HMQ is not needed any more, call
 2046 C<perl_hmq_UNSET(serve)>.  Perl process will automatically morph/unmorph itself
 2047 into/from a PM process if HMQ is needed/not-needed.  Perl will automatically
 2048 enable/disable C<WM_QUIT> message during shutdown if the message queue is
 2049 served/not-served.
 2050 
 2051 B<NOTE>.  If during a shutdown there is a message queue which did not disable
 2052 WM_QUIT, and which did not process the received WM_QUIT message, the
 2053 shutdown will be automatically cancelled.  Do not call C<perl_hmq_GET(1)>
 2054 unless you are going to process messages on an orderly basis.
 2055 
 2056 =item Treating errors reported by OS/2 API
 2057 
 2058 There are two principal conventions (it is useful to call them C<Dos*>
 2059 and C<Win*> - though this part of the function signature is not always
 2060 determined by the name of the API) of reporting the error conditions
 2061 of OS/2 API.  Most of C<Dos*> APIs report the error code as the result
 2062 of the call (so 0 means success, and there are many types of errors).
 2063 Most of C<Win*> API report success/fail via the result being
 2064 C<TRUE>/C<FALSE>; to find the reason for the failure one should call
 2065 WinGetLastError() API.
 2066 
 2067 Some C<Win*> entry points also overload a "meaningful" return value
 2068 with the error indicator; having a 0 return value indicates an error.
 2069 Yet some other C<Win*> entry points overload things even more, and 0
 2070 return value may mean a successful call returning a valid value 0, as
 2071 well as an error condition; in the case of a 0 return value one should
 2072 call WinGetLastError() API to distinguish a successful call from a
 2073 failing one.
 2074 
 2075 By convention, all the calls to OS/2 API should indicate their
 2076 failures by resetting $^E.  All the Perl-accessible functions which
 2077 call OS/2 API may be broken into two classes: some die()s when an API
 2078 error is encountered, the other report the error via a false return
 2079 value (of course, this does not concern Perl-accessible functions
 2080 which I<expect> a failure of the OS/2 API call, having some workarounds
 2081 coded).
 2082 
 2083 Obviously, in the situation of the last type of the signature of an OS/2
 2084 API, it is must more convenient for the users if the failure is
 2085 indicated by die()ing: one does not need to check $^E to know that
 2086 something went wrong.  If, however, this solution is not desirable by
 2087 some reason, the code in question should reset $^E to 0 before making
 2088 this OS/2 API call, so that the caller of this Perl-accessible
 2089 function has a chance to distinguish a success-but-0-return value from
 2090 a failure.  (One may return undef as an alternative way of reporting
 2091 an error.)
 2092 
 2093 The macros to simplify this type of error propagation are
 2094 
 2095 =over
 2096 
 2097 =item C<CheckOSError(expr)>
 2098 
 2099 Returns true on error, sets $^E.  Expects expr() be a call of
 2100 C<Dos*>-style API.
 2101 
 2102 =item C<CheckWinError(expr)>
 2103 
 2104 Returns true on error, sets $^E.  Expects expr() be a call of
 2105 C<Win*>-style API.
 2106 
 2107 =item C<SaveWinError(expr)>
 2108 
 2109 Returns C<expr>, sets $^E from WinGetLastError() if C<expr> is false.
 2110 
 2111 =item C<SaveCroakWinError(expr,die,name1,name2)>
 2112 
 2113 Returns C<expr>, sets $^E from WinGetLastError() if C<expr> is false,
 2114 and die()s if C<die> and $^E are true.  The message to die is the
 2115 concatenated strings C<name1> and C<name2>, separated by C<": "> from
 2116 the contents of $^E.
 2117 
 2118 =item C<WinError_2_Perl_rc>
 2119 
 2120 Sets C<Perl_rc> to the return value of WinGetLastError().
 2121 
 2122 =item C<FillWinError>
 2123 
 2124 Sets C<Perl_rc> to the return value of WinGetLastError(), and sets $^E
 2125 to the corresponding value.
 2126 
 2127 =item C<FillOSError(rc)>
 2128 
 2129 Sets C<Perl_rc> to C<rc>, and sets $^E to the corresponding value.
 2130 
 2131 =back
 2132 
 2133 =item Loading DLLs and ordinals in DLLs
 2134 
 2135 Some DLLs are only present in some versions of OS/2, or in some
 2136 configurations of OS/2.  Some exported entry points are present only
 2137 in DLLs shipped with some versions of OS/2.  If these DLLs and entry
 2138 points were linked directly for a Perl executable/DLL or from a Perl
 2139 extensions, this binary would work only with the specified
 2140 versions/setups.  Even if these entry points were not needed, the
 2141 I<load> of the executable (or DLL) would fail.
 2142 
 2143 For example, many newer useful APIs are not present in OS/2 v2; many
 2144 PM-related APIs require DLLs not available on floppy-boot setup.
 2145 
 2146 To make these calls fail I<only when the calls are executed>, one
 2147 should call these API via a dynamic linking API.  There is a subsystem
 2148 in Perl to simplify such type of calls.  A large number of entry
 2149 points available for such linking is provided (see C<entries_ordinals>
 2150 - and also C<PMWIN_entries> - in F<os2ish.h>).  These ordinals can be
 2151 accessed via the APIs:
 2152 
 2153  CallORD(), DeclFuncByORD(), DeclVoidFuncByORD(),
 2154  DeclOSFuncByORD(), DeclWinFuncByORD(), AssignFuncPByORD(),
 2155  DeclWinFuncByORD_CACHE(), DeclWinFuncByORD_CACHE_survive(),
 2156  DeclWinFuncByORD_CACHE_resetError_survive(),
 2157  DeclWinFunc_CACHE(), DeclWinFunc_CACHE_resetError(),
 2158  DeclWinFunc_CACHE_survive(), DeclWinFunc_CACHE_resetError_survive()
 2159 
 2160 See the header files and the C code in the supplied OS/2-related
 2161 modules for the details on usage of these functions.
 2162 
 2163 Some of these functions also combine dynaloading semantic with the
 2164 error-propagation semantic discussed above.
 2165 
 2166 =back
 2167 
 2168 =head1 Perl flavors
 2169 
 2170 Because of idiosyncrasies of OS/2 one cannot have all the eggs in the
 2171 same basket (though EMX environment tries hard to overcome this
 2172 limitations, so the situation may somehow improve). There are 4
 2173 executables for Perl provided by the distribution:
 2174 
 2175 =head2 F<perl.exe>
 2176 
 2177 The main workhorse. This is a chimera executable: it is compiled as an
 2178 C<a.out>-style executable, but is linked with C<omf>-style dynamic
 2179 library F<perl.dll>, and with dynamic CRT DLL. This executable is a
 2180 VIO application.
 2181 
 2182 It can load perl dynamic extensions, and it can fork().
 2183 
 2184 B<Note.> Keep in mind that fork() is needed to open a pipe to yourself.
 2185 
 2186 =head2 F<perl_.exe>
 2187 
 2188 This is a statically linked C<a.out>-style executable. It cannot
 2189 load dynamic Perl extensions. The executable supplied in binary
 2190 distributions has a lot of extensions prebuilt, thus the above restriction is 
 2191 important only if you use custom-built extensions. This executable is a VIO
 2192 application.
 2193 
 2194 I<This is the only executable with does not require OS/2.> The
 2195 friends locked into C<M$> world would appreciate the fact that this
 2196 executable runs under DOS, Win0.3*, Win0.95 and WinNT with an
 2197 appropriate extender. See L</"Other OSes">.
 2198 
 2199 =head2 F<perl__.exe>
 2200 
 2201 This is the same executable as F<perl___.exe>, but it is a PM
 2202 application. 
 2203 
 2204 B<Note.> Usually (unless explicitly redirected during the startup)
 2205 STDIN, STDERR, and STDOUT of a PM
 2206 application are redirected to F<nul>. However, it is possible to I<see>
 2207 them if you start C<perl__.exe> from a PM program which emulates a
 2208 console window, like I<Shell mode> of Emacs or EPM. Thus it I<is
 2209 possible> to use Perl debugger (see L<perldebug>) to debug your PM
 2210 application (but beware of the message loop lockups - this will not
 2211 work if you have a message queue to serve, unless you hook the serving
 2212 into the getc() function of the debugger).
 2213 
 2214 Another way to see the output of a PM program is to run it as
 2215 
 2216   pm_prog args 2>&1 | cat -
 2217 
 2218 with a shell I<different> from F<cmd.exe>, so that it does not create
 2219 a link between a VIO session and the session of C<pm_porg>.  (Such a link
 2220 closes the VIO window.)  E.g., this works with F<sh.exe> - or with Perl!
 2221 
 2222   open P, 'pm_prog args 2>&1 |' or die;
 2223   print while <P>;
 2224 
 2225 The flavor F<perl__.exe> is required if you want to start your program without
 2226 a VIO window present, but not C<detach>ed (run C<help detach> for more info).
 2227 Very useful for extensions which use PM, like C<Perl/Tk> or C<OpenGL>.
 2228 
 2229 Note also that the differences between PM and VIO executables are only
 2230 in the I<default> behaviour.  One can start I<any> executable in
 2231 I<any> kind of session by using the arguments C</fs>, C</pm> or
 2232 C</win> switches of the command C<start> (of F<CMD.EXE> or a similar
 2233 shell).  Alternatively, one can use the numeric first argument of the
 2234 C<system> Perl function (see L<OS2::Process>).
 2235 
 2236 =head2 F<perl___.exe>
 2237 
 2238 This is an C<omf>-style executable which is dynamically linked to
 2239 F<perl.dll> and CRT DLL. I know no advantages of this executable
 2240 over C<perl.exe>, but it cannot fork() at all. Well, one advantage is
 2241 that the build process is not so convoluted as with C<perl.exe>.
 2242 
 2243 It is a VIO application.
 2244 
 2245 =head2 Why strange names?
 2246 
 2247 Since Perl processes the C<#!>-line (cf. 
 2248 L<perlrun/DESCRIPTION>, L<perlrun/Command Switches>,
 2249 L<perldiag/"No Perl script found in input">), it should know when a
 2250 program I<is a Perl>. There is some naming convention which allows
 2251 Perl to distinguish correct lines from wrong ones. The above names are
 2252 almost the only names allowed by this convention which do not contain
 2253 digits (which have absolutely different semantics).
 2254 
 2255 =head2 Why dynamic linking?
 2256 
 2257 Well, having several executables dynamically linked to the same huge
 2258 library has its advantages, but this would not substantiate the
 2259 additional work to make it compile. The reason is the complicated-to-developers
 2260 but very quick and convenient-to-users "hard" dynamic linking used by OS/2.
 2261 
 2262 There are two distinctive features of the dyna-linking model of OS/2:
 2263 first, all the references to external functions are resolved at the compile time;
 2264 second, there is no runtime fixup of the DLLs after they are loaded into memory.
 2265 The first feature is an enormous advantage over other models: it avoids
 2266 conflicts when several DLLs used by an application export entries with
 2267 the same name.  In such cases "other" models of dyna-linking just choose
 2268 between these two entry points using some random criterion - with predictable
 2269 disasters as results.  But it is the second feature which requires the build
 2270 of F<perl.dll>.
 2271 
 2272 The address tables of DLLs are patched only once, when they are
 2273 loaded. The addresses of the entry points into DLLs are guaranteed to be
 2274 the same for all the programs which use the same DLL.  This removes the
 2275 runtime fixup - once DLL is loaded, its code is read-only.
 2276 
 2277 While this allows some (significant?) performance advantages, this makes life
 2278 much harder for developers, since the above scheme makes it impossible
 2279 for a DLL to be "linked" to a symbol in the F<.EXE> file.  Indeed, this
 2280 would need a DLL to have different relocations tables for the
 2281 (different) executables which use this DLL.
 2282 
 2283 However, a dynamically loaded Perl extension is forced to use some symbols
 2284 from the perl
 2285 executable, e.g., to know how to find the arguments to the functions:
 2286 the arguments live on the perl
 2287 internal evaluation stack. The solution is to put the main code of
 2288 the interpreter into a DLL, and make the F<.EXE> file which just loads
 2289 this DLL into memory and supplies command-arguments.  The extension DLL
 2290 cannot link to symbols in F<.EXE>, but it has no problem linking
 2291 to symbols in the F<.DLL>.
 2292 
 2293 This I<greatly> increases the load time for the application (as well as
 2294 complexity of the compilation). Since interpreter is in a DLL,
 2295 the C RTL is basically forced to reside in a DLL as well (otherwise
 2296 extensions would not be able to use CRT).  There are some advantages if
 2297 you use different flavors of perl, such as running F<perl.exe> and
 2298 F<perl__.exe> simultaneously: they share the memory of F<perl.dll>.
 2299 
 2300 B<NOTE>.  There is one additional effect which makes DLLs more wasteful:
 2301 DLLs are loaded in the shared memory region, which is a scarse resource
 2302 given the 512M barrier of the "standard" OS/2 virtual memory.  The code of
 2303 F<.EXE> files is also shared by all the processes which use the particular
 2304 F<.EXE>, but they are "shared in the private address space of the process";
 2305 this is possible because the address at which different sections
 2306 of the F<.EXE> file are loaded is decided at compile-time, thus all the
 2307 processes have these sections loaded at same addresses, and no fixup
 2308 of internal links inside the F<.EXE> is needed.
 2309 
 2310 Since DLLs may be loaded at run time, to have the same mechanism for DLLs
 2311 one needs to have the address range of I<any of the loaded> DLLs in the
 2312 system to be available I<in all the processes> which did not load a particular
 2313 DLL yet.  This is why the DLLs are mapped to the shared memory region.
 2314 
 2315 =head2 Why chimera build?
 2316 
 2317 Current EMX environment does not allow DLLs compiled using Unixish
 2318 C<a.out> format to export symbols for data (or at least some types of
 2319 data). This forces C<omf>-style compile of F<perl.dll>.
 2320 
 2321 Current EMX environment does not allow F<.EXE> files compiled in
 2322 C<omf> format to fork(). fork() is needed for exactly three Perl
 2323 operations:
 2324 
 2325 =over 4
 2326 
 2327 =item *
 2328 
 2329 explicit fork() in the script, 
 2330 
 2331 =item *
 2332 
 2333 C<open FH, "|-">
 2334 
 2335 =item *
 2336 
 2337 C<open FH, "-|">, in other words, opening pipes to itself.
 2338 
 2339 =back
 2340 
 2341 While these operations are not questions of life and death, they are
 2342 needed for a lot of
 2343 useful scripts. This forces C<a.out>-style compile of
 2344 F<perl.exe>.
 2345 
 2346 
 2347 =head1 ENVIRONMENT
 2348 
 2349 Here we list environment variables with are either OS/2- and DOS- and
 2350 Win*-specific, or are more important under OS/2 than under other OSes.
 2351 
 2352 =head2 C<PERLLIB_PREFIX>
 2353 
 2354 Specific for EMX port. Should have the form
 2355 
 2356   path1;path2
 2357 
 2358 or
 2359 
 2360   path1 path2
 2361 
 2362 If the beginning of some prebuilt path matches F<path1>, it is
 2363 substituted with F<path2>.
 2364 
 2365 Should be used if the perl library is moved from the default
 2366 location in preference to C<PERL(5)LIB>, since this would not leave wrong
 2367 entries in @INC.  For example, if the compiled version of perl looks for @INC
 2368 in F<f:/perllib/lib>, and you want to install the library in
 2369 F<h:/opt/gnu>, do
 2370 
 2371   set PERLLIB_PREFIX=f:/perllib/lib;h:/opt/gnu
 2372 
 2373 This will cause Perl with the prebuilt @INC of
 2374 
 2375   f:/perllib/lib/5.00553/os2
 2376   f:/perllib/lib/5.00553
 2377   f:/perllib/lib/site_perl/5.00553/os2
 2378   f:/perllib/lib/site_perl/5.00553
 2379   .
 2380 
 2381 to use the following @INC:
 2382 
 2383   h:/opt/gnu/5.00553/os2
 2384   h:/opt/gnu/5.00553
 2385   h:/opt/gnu/site_perl/5.00553/os2
 2386   h:/opt/gnu/site_perl/5.00553
 2387   .
 2388 
 2389 =head2 C<PERL_BADLANG>
 2390 
 2391 If 0, perl ignores setlocale() failing. May be useful with some
 2392 strange I<locale>s.
 2393 
 2394 =head2 C<PERL_BADFREE>
 2395 
 2396 If 0, perl would not warn of in case of unwarranted free(). With older
 2397 perls this might be
 2398 useful in conjunction with the module DB_File, which was buggy when
 2399 dynamically linked and OMF-built.
 2400 
 2401 Should not be set with newer Perls, since this may hide some I<real> problems.
 2402 
 2403 =head2 C<PERL_SH_DIR>
 2404 
 2405 Specific for EMX port. Gives the directory part of the location for
 2406 F<sh.exe>.
 2407 
 2408 =head2 C<USE_PERL_FLOCK>
 2409 
 2410 Specific for EMX port. Since L<flock(3)> is present in EMX, but is not 
 2411 functional, it is emulated by perl.  To disable the emulations, set 
 2412 environment variable C<USE_PERL_FLOCK=0>.
 2413 
 2414 =head2 C<TMP> or C<TEMP>
 2415 
 2416 Specific for EMX port. Used as storage place for temporary files.
 2417 
 2418 =head1 Evolution
 2419 
 2420 Here we list major changes which could make you by surprise.
 2421 
 2422 =head2 Text-mode filehandles
 2423 
 2424 Starting from version 5.8, Perl uses a builtin translation layer for
 2425 text-mode files.  This replaces the efficient well-tested EMX layer by
 2426 some code which should be best characterized as a "quick hack".
 2427 
 2428 In addition to possible bugs and an inability to follow changes to the
 2429 translation policy with off/on switches of TERMIO translation, this
 2430 introduces a serious incompatible change: before sysread() on
 2431 text-mode filehandles would go through the translation layer, now it
 2432 would not.
 2433 
 2434 =head2 Priorities
 2435 
 2436 C<setpriority> and C<getpriority> are not compatible with earlier
 2437 ports by Andreas Kaiser. See C<"setpriority, getpriority">.
 2438 
 2439 =head2 DLL name mangling: pre 5.6.2
 2440 
 2441 With the release 5.003_01 the dynamically loadable libraries
 2442 should be rebuilt when a different version of Perl is compiled. In particular,
 2443 DLLs (including F<perl.dll>) are now created with the names
 2444 which contain a checksum, thus allowing workaround for OS/2 scheme of
 2445 caching DLLs.
 2446 
 2447 It may be possible to code a simple workaround which would 
 2448 
 2449 =over
 2450 
 2451 =item *
 2452 
 2453 find the old DLLs looking through the old @INC;
 2454 
 2455 =item *
 2456 
 2457 mangle the names according to the scheme of new perl and copy the DLLs to
 2458 these names;
 2459 
 2460 =item *
 2461 
 2462 edit the internal C<LX> tables of DLL to reflect the change of the name
 2463 (probably not needed for Perl extension DLLs, since the internally coded names
 2464 are not used for "specific" DLLs, they used only for "global" DLLs).
 2465 
 2466 =item *
 2467 
 2468 edit the internal C<IMPORT> tables and change the name of the "old"
 2469 F<perl????.dll> to the "new" F<perl????.dll>.
 2470 
 2471 =back
 2472 
 2473 =head2 DLL name mangling: 5.6.2 and beyond
 2474 
 2475 In fact mangling of I<extension> DLLs was done due to misunderstanding
 2476 of the OS/2 dynaloading model.  OS/2 (effectively) maintains two
 2477 different tables of loaded DLL:
 2478 
 2479 =over
 2480 
 2481 =item Global DLLs
 2482 
 2483 those loaded by the base name from C<LIBPATH>; including those
 2484 associated at link time;
 2485 
 2486 =item specific DLLs
 2487 
 2488 loaded by the full name.
 2489 
 2490 =back
 2491 
 2492 When resolving a request for a global DLL, the table of already-loaded
 2493 specific DLLs is (effectively) ignored; moreover, specific DLLs are
 2494 I<always> loaded from the prescribed path.
 2495 
 2496 There is/was a minor twist which makes this scheme fragile: what to do
 2497 with DLLs loaded from
 2498 
 2499 =over
 2500 
 2501 =item C<BEGINLIBPATH> and C<ENDLIBPATH>
 2502 
 2503 (which depend on the process)
 2504 
 2505 =item F<.> from C<LIBPATH>
 2506 
 2507 which I<effectively> depends on the process (although C<LIBPATH> is the
 2508 same for all the processes).
 2509 
 2510 =back
 2511 
 2512 Unless C<LIBPATHSTRICT> is set to C<T> (and the kernel is after
 2513 2000/09/01), such DLLs are considered to be global.  When loading a
 2514 global DLL it is first looked in the table of already-loaded global
 2515 DLLs.  Because of this the fact that one executable loaded a DLL from
 2516 C<BEGINLIBPATH> and C<ENDLIBPATH>, or F<.> from C<LIBPATH> may affect
 2517 I<which> DLL is loaded when I<another> executable requests a DLL with
 2518 the same name.  I<This> is the reason for version-specific mangling of
 2519 the DLL name for perl DLL.
 2520 
 2521 Since the Perl extension DLLs are always loaded with the full path,
 2522 there is no need to mangle their names in a version-specific ways:
 2523 their directory already reflects the corresponding version of perl,
 2524 and @INC takes into account binary compatibility with older version.
 2525 Starting from C<5.6.2> the name mangling scheme is fixed to be the
 2526 same as for Perl 5.005_53 (same as in a popular binary release).  Thus
 2527 new Perls will be able to I<resolve the names> of old extension DLLs
 2528 if @INC allows finding their directories.
 2529 
 2530 However, this still does not guarantee that these DLL may be loaded.
 2531 The reason is the mangling of the name of the I<Perl DLL>.  And since
 2532 the extension DLLs link with the Perl DLL, extension DLLs for older
 2533 versions would load an older Perl DLL, and would most probably
 2534 segfault (since the data in this DLL is not properly initialized).
 2535 
 2536 There is a partial workaround (which can be made complete with newer
 2537 OS/2 kernels): create a forwarder DLL with the same name as the DLL of
 2538 the older version of Perl, which forwards the entry points to the
 2539 newer Perl's DLL.  Make this DLL accessible on (say) the C<BEGINLIBPATH> of
 2540 the new Perl executable.  When the new executable accesses old Perl's
 2541 extension DLLs, they would request the old Perl's DLL by name, get the
 2542 forwarder instead, so effectively will link with the currently running
 2543 (new) Perl DLL.
 2544 
 2545 This may break in two ways:
 2546 
 2547 =over
 2548 
 2549 =item *
 2550 
 2551 Old perl executable is started when a new executable is running has
 2552 loaded an extension compiled for the old executable (ouph!).  In this
 2553 case the old executable will get a forwarder DLL instead of the old
 2554 perl DLL, so would link with the new perl DLL.  While not directly
 2555 fatal, it will behave the same as new executable.  This beats the whole
 2556 purpose of explicitly starting an old executable.
 2557 
 2558 =item *
 2559 
 2560 A new executable loads an extension compiled for the old executable
 2561 when an old perl executable is running.  In this case the extension
 2562 will not pick up the forwarder - with fatal results.
 2563 
 2564 =back
 2565 
 2566 With support for C<LIBPATHSTRICT> this may be circumvented - unless
 2567 one of DLLs is started from F<.> from C<LIBPATH> (I do not know
 2568 whether C<LIBPATHSTRICT> affects this case).
 2569 
 2570 B<REMARK>.  Unless newer kernels allow F<.> in C<BEGINLIBPATH> (older
 2571 do not), this mess cannot be completely cleaned.  (It turns out that
 2572 as of the beginning of 2002, F<.> is not allowed, but F<.\.> is - and
 2573 it has the same effect.)
 2574 
 2575 
 2576 B<REMARK>.  C<LIBPATHSTRICT>, C<BEGINLIBPATH> and C<ENDLIBPATH> are
 2577 not environment variables, although F<cmd.exe> emulates them on C<SET
 2578 ...> lines.  From Perl they may be accessed by
 2579 L<Cwd::extLibpath|/Cwd::extLibpath([type])> and
 2580 L<Cwd::extLibpath_set|/Cwd::extLibpath_set( path [, type ] )>.
 2581 
 2582 =head2 DLL forwarder generation
 2583 
 2584 Assume that the old DLL is named F<perlE0AC.dll> (as is one for
 2585 5.005_53), and the new version is 5.6.1.  Create a file
 2586 F<perl5shim.def-leader> with
 2587 
 2588   LIBRARY 'perlE0AC' INITINSTANCE TERMINSTANCE
 2589   DESCRIPTION '@#perl5-porters@perl.org:5.006001#@ Perl module for 5.00553 -> Perl 5.6.1 forwarder'
 2590   CODE LOADONCALL
 2591   DATA LOADONCALL NONSHARED MULTIPLE
 2592   EXPORTS
 2593 
 2594 modifying the versions/names as needed.  Run
 2595 
 2596  perl -wnle "next if 0../EXPORTS/; print qq(  \"$1\")
 2597                                           if /\"(\w+)\"/" perl5.def >lst
 2598 
 2599 in the Perl build directory (to make the DLL smaller replace perl5.def
 2600 with the definition file for the older version of Perl if present).
 2601 
 2602  cat perl5shim.def-leader lst >perl5shim.def
 2603  gcc -Zomf -Zdll -o perlE0AC.dll perl5shim.def -s -llibperl
 2604 
 2605 (ignore multiple C<warning L4085>).
 2606 
 2607 =head2 Threading
 2608 
 2609 As of release 5.003_01 perl is linked to multithreaded C RTL
 2610 DLL.  If perl itself is not compiled multithread-enabled, so will not be perl's
 2611 malloc(). However, extensions may use multiple thread on their own
 2612 risk. 
 2613 
 2614 This was needed to compile C<Perl/Tk> for XFree86-OS/2 out-of-the-box, and
 2615 link with DLLs for other useful libraries, which typically are compiled
 2616 with C<-Zmt -Zcrtdll>.
 2617 
 2618 =head2 Calls to external programs
 2619 
 2620 Due to a popular demand the perl external program calling has been
 2621 changed wrt Andreas Kaiser's port.  I<If> perl needs to call an
 2622 external program I<via shell>, the F<f:/bin/sh.exe> will be called, or
 2623 whatever is the override, see L</"C<PERL_SH_DIR>">.
 2624 
 2625 Thus means that you need to get some copy of a F<sh.exe> as well (I
 2626 use one from pdksh). The path F<F:/bin> above is set up automatically during
 2627 the build to a correct value on the builder machine, but is
 2628 overridable at runtime,
 2629 
 2630 B<Reasons:> a consensus on C<perl5-porters> was that perl should use
 2631 one non-overridable shell per platform. The obvious choices for OS/2
 2632 are F<cmd.exe> and F<sh.exe>. Having perl build itself would be impossible
 2633 with F<cmd.exe> as a shell, thus I picked up C<sh.exe>. This assures almost
 2634 100% compatibility with the scripts coming from *nix. As an added benefit 
 2635 this works as well under DOS if you use DOS-enabled port of pdksh 
 2636 (see L</Prerequisites>).
 2637 
 2638 B<Disadvantages:> currently F<sh.exe> of pdksh calls external programs
 2639 via fork()/exec(), and there is I<no> functioning exec() on
 2640 OS/2. exec() is emulated by EMX by an asynchronous call while the caller
 2641 waits for child completion (to pretend that the C<pid> did not change). This
 2642 means that 1 I<extra> copy of F<sh.exe> is made active via fork()/exec(),
 2643 which may lead to some resources taken from the system (even if we do
 2644 not count extra work needed for fork()ing).
 2645 
 2646 Note that this a lesser issue now when we do not spawn F<sh.exe>
 2647 unless needed (metachars found).
 2648 
 2649 One can always start F<cmd.exe> explicitly via
 2650 
 2651   system 'cmd', '/c', 'mycmd', 'arg1', 'arg2', ...
 2652 
 2653 If you need to use F<cmd.exe>, and do not want to hand-edit thousands of your
 2654 scripts, the long-term solution proposed on p5-p is to have a directive
 2655 
 2656   use OS2::Cmd;
 2657 
 2658 which will override system(), exec(), C<``>, and
 2659 C<open(,'...|')>. With current perl you may override only system(),
 2660 readpipe() - the explicit version of C<``>, and maybe exec(). The code
 2661 will substitute the one-argument call to system() by
 2662 C<CORE::system('cmd.exe', '/c', shift)>.
 2663 
 2664 If you have some working code for C<OS2::Cmd>, please send it to me,
 2665 I will include it into distribution. I have no need for such a module, so
 2666 cannot test it.
 2667 
 2668 For the details of the current situation with calling external programs,
 2669 see L<Starting OSE<sol>2 (and DOS) programs under Perl>.  Set us mention a couple
 2670 of features:
 2671 
 2672 =over 4
 2673 
 2674 =item *
 2675 
 2676 External scripts may be called by their basename.  Perl will try the same
 2677 extensions as when processing B<-S> command-line switch.
 2678 
 2679 =item *
 2680 
 2681 External scripts starting with C<#!> or C<extproc > will be executed directly,
 2682 without calling the shell, by calling the program specified on the rest of
 2683 the first line.
 2684 
 2685 =back
 2686 
 2687 =head2 Memory allocation
 2688 
 2689 Perl uses its own malloc() under OS/2 - interpreters are usually malloc-bound
 2690 for speed, but perl is not, since its malloc is lightning-fast.
 2691 Perl-memory-usage-tuned benchmarks show that Perl's malloc is 5 times quicker
 2692 than EMX one.  I do not have convincing data about memory footprint, but
 2693 a (pretty random) benchmark showed that Perl's one is 5% better.
 2694 
 2695 Combination of perl's malloc() and rigid DLL name resolution creates
 2696 a special problem with library functions which expect their return value to
 2697 be free()d by system's free(). To facilitate extensions which need to call 
 2698 such functions, system memory-allocation functions are still available with
 2699 the prefix C<emx_> added. (Currently only DLL perl has this, it should 
 2700 propagate to F<perl_.exe> shortly.)
 2701 
 2702 =head2 Threads
 2703 
 2704 One can build perl with thread support enabled by providing C<-D usethreads>
 2705 option to F<Configure>.  Currently OS/2 support of threads is very 
 2706 preliminary.
 2707 
 2708 Most notable problems: 
 2709 
 2710 =over 4
 2711 
 2712 =item C<COND_WAIT> 
 2713 
 2714 may have a race condition (but probably does not due to edge-triggered
 2715 nature of OS/2 Event semaphores).  (Needs a reimplementation (in terms of chaining
 2716 waiting threads, with the linked list stored in per-thread structure?)?)
 2717 
 2718 =item F<os2.c>
 2719 
 2720 has a couple of static variables used in OS/2-specific functions.  (Need to be
 2721 moved to per-thread structure, or serialized?)
 2722 
 2723 =back
 2724 
 2725 Note that these problems should not discourage experimenting, since they
 2726 have a low probability of affecting small programs.
 2727 
 2728 =head1 BUGS
 2729 
 2730 This description is not updated often (since 5.6.1?), see F<./os2/Changes>
 2731 for more info.
 2732 
 2733 =cut
 2734 
 2735 OS/2 extensions
 2736 ~~~~~~~~~~~~~~~
 2737 I include 3 extensions by Andreas Kaiser, OS2::REXX, OS2::UPM, and OS2::FTP, 
 2738 into my ftp directory, mirrored on CPAN. I made
 2739 some minor changes needed to compile them by standard tools. I cannot 
 2740 test UPM and FTP, so I will appreciate your feedback. Other extensions
 2741 there are OS2::ExtAttr, OS2::PrfDB for tied access to EAs and .INI
 2742 files - and maybe some other extensions at the time you read it.
 2743 
 2744 Note that OS2 perl defines 2 pseudo-extension functions
 2745 OS2::Copy::copy and DynaLoader::mod2fname (many more now, see
 2746 L</Prebuilt methods>).
 2747 
 2748 The -R switch of older perl is deprecated. If you need to call a REXX code
 2749 which needs access to variables, include the call into a REXX compartment
 2750 created by 
 2751 	REXX_call {...block...};
 2752 
 2753 Two new functions are supported by REXX code, 
 2754 	REXX_eval 'string';
 2755 	REXX_eval_with 'string', REXX_function_name => \&perl_sub_reference;
 2756 
 2757 If you have some other extensions you want to share, send the code to
 2758 me.  At least two are available: tied access to EA's, and tied access
 2759 to system databases.
 2760 
 2761 =head1 AUTHOR
 2762 
 2763 Ilya Zakharevich, cpan@ilyaz.org
 2764 
 2765 =head1 SEE ALSO
 2766 
 2767 perl(1).
 2768 
 2769 =cut
 2770