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Platform Specific

Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT.

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NAME

perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT.

SYNOPSIS

One can read this document in the following formats:

  1. man perlos2
    2.  
  2. view perl perlos2
    3.  
  3. explorer perlos2.html
    4.  
  4. info perlos2
    5.

to list some (not all may be available simultaneously), or it maybe read as is: either as README.os2, or pod/perlos2.pod.

To read the .INF version of documentation (very recommended)outside of OS/2, one needs an IBM's reader (may be available on IBMftp sites (?) (URL anyone?)) or shipped with PC DOS 7.0 and IBM'sVisual Age C++ 3.5.

A copy of a Win* viewer is contained in the "Just add OS/2 Warp" package

  1.   ftp://ftp.software.ibm.com/ps/products/os2/tools/jaow/jaow.zip
    2.

in ?:\JUST_ADD\view.exe. This gives one an access to EMX's .INF docs as well (text form is available in /emx/doc in EMX's distribution). There is also a different viewer named xview.

Note that if you have lynx.exe or netscape.exe installed, you can follow WWW linksfrom this document in .INF format. If you have EMX docs installed correctly, you can follow library links (you need to have view emxbookworking by setting EMXBOOK environment variable as it is describedin EMX docs).

DESCRIPTION

Target

The target is to make OS/2 one of the best supported platform forusing/building/developing Perl and Perl applications, as well asmake Perl the best language to use under OS/2. The secondary target isto try to make this work under DOS and Win* as well (but not too hard).

The current state is quite close to this target. Known limitations:

  • Some *nix programs use fork() a lot; with the mostly useful flavors ofperl for OS/2 (there are several built simultaneously) this issupported; but some flavors do not support this (e.g., when Perl iscalled from inside REXX). Using fork() afteruseing dynamically loading extensions would not work with very oldversions of EMX.

  • You need a separate perl executable perl__.exe (see perl__.exe)if you want to use PM code in your application (as Perl/Tk or OpenGLPerl modules do) without having a text-mode window present.

    While using the standard perl.exe from a text-mode window is possibletoo, I have seen cases when this causes degradation of the system stability.Using perl__.exe avoids such a degradation.

  • There is no simple way to access WPS objects. The only way I knowis via OS2::REXX and SOM extensions (see OS2::REXX, SOM).However, we do not have access toconvenience methods of Object-REXX. (Is it possible at all? I knowof no Object-REXX API.) The SOM extension (currently in alpha-text)may eventually remove this shortcoming; however, due to the fact thatDII is not supported by the SOM module, using SOM is not asconvenient as one would like it.

Please keep this list up-to-date by informing me about other items.

Other OSes

Since OS/2 port of perl uses a remarkable EMX environment, it canrun (and build extensions, and - possibly - be built itself) under anyenvironment which can run EMX. The current list is DOS,DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT. Out of many perl flavors,only one works, see perl_.exe.

Note that not all features of Perl are available under theseenvironments. This depends on the features the extender - mostprobably RSX - decided to implement.

Cf. Prerequisites.

Prerequisites

  • EMX

    EMX runtime is required (may be substituted by RSX). Note thatit is possible to make perl_.exe to run under DOS without anyexternal support by binding emx.exe/rsx.exe to it, see emxbind. Notethat under DOS for best results one should use RSX runtime, whichhas much more functions working (like fork, popen and so on). Infact RSX is required if there is no VCPI present. Note theRSX requires DPMI. Many implementations of DPMI are known to be verybuggy, beware!

    Only the latest runtime is supported, currently 0.9d fix 03. Perl may rununder earlier versions of EMX, but this is not tested.

    One can get different parts of EMX from, say

    1.   ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/emx+gcc/
      2.  
    2.   http://hobbes.nmsu.edu/h-browse.php?dir=/pub/os2/dev/emx/v0.9d/
      3.

    The runtime component should have the name emxrt.zip.

    NOTE. When using emx.exe/rsx.exe, it is enough to have them on your path. Onedoes not need to specify them explicitly (though this

    1.   emx perl_.exe -de 0
      2.

    will work as well.)

  • RSX

    To run Perl on DPMI platforms one needs RSX runtime. This isneeded under DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT (see Other OSes). RSX would not work with VCPIonly, as EMX would, it requires DMPI.

    Having RSX and the latest sh.exe one gets a fully functional*nix-ish environment under DOS, say, fork, `` andpipe-open work. In fact, MakeMaker works (for static build), so onecan have Perl development environment under DOS.

    One can get RSX from, say

    1.   http://cd.textfiles.com/hobbesos29804/disk1/EMX09C/
      2.  
    2.   ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/emx+gcc/contrib/
      3.

    Contact the author on rainer@mathematik.uni-bielefeld.de.

    The latest sh.exe with DOS hooks is available in

    1.   http://www.ilyaz.org/software/os2/
      2.

    as sh_dos.zip or under similar names starting with sh, pdksh etc.

  • HPFS

    Perl does not care about file systems, but the perl library containsmany files with long names, so to install it intact one needs a filesystem which supports long file names.

    Note that if you do not plan to build the perl itself, it may bepossible to fool EMX to truncate file names. This is not supported,read EMX docs to see how to do it.

  • pdksh

    To start external programs with complicated command lines (like withpipes in between, and/or quoting of arguments), Perl uses an externalshell. With EMX port such shell should be named sh.exe, and locatedeither in the wired-in-during-compile locations (usually F:/bin),or in configurable location (see PERL_SH_DIR).

    For best results use EMX pdksh. The standard binary (5.2.14 or later) runsunder DOS (with RSX) as well, see

    1.   http://www.ilyaz.org/software/os2/
      2.

Starting Perl programs under OS/2 (and DOS and...)

Start your Perl program foo.pl with arguments arg1 arg2 arg3 thesame way as on any other platform, by

  1. perl foo.pl arg1 arg2 arg3
    2.

If you want to specify perl options -my_opts to the perl itself (asopposed to your program), use

  1. perl -my_opts foo.pl arg1 arg2 arg3
    2.

Alternately, if you use OS/2-ish shell, like CMD or 4os2, putthe following at the start of your perl script:

  1. extproc perl -S -my_opts
    2.

rename your program to foo.cmd, and start it by typing

  1. foo arg1 arg2 arg3
    2.

Note that because of stupid OS/2 limitations the full path of the perlscript is not available when you use extproc, thus you are forced touse -S perl switch, and your script should be on the PATH. As a plusside, if you know a full path to your script, you may still start itwith

  1. perl ../../blah/foo.cmd arg1 arg2 arg3
    2.

(note that the argument -my_opts is taken care of by the extproc linein your script, see extproc on the first line).

To understand what the above magic does, read perl docs about -Sswitch - see perlrun, and cmdref about extproc:

  1. view perl perlrun
    2.  
  2. man perlrun
    3.  
  3. view cmdref extproc
    4.  
  4. help extproc
    5.

or whatever method you prefer.

There are also endless possibilities to use executable extensions of4os2, associations of WPS and so on... However, if you use*nixish shell (like sh.exe supplied in the binary distribution),you need to follow the syntax specified in Command Switches in perlrun.

Note that -S switch supports scripts with additional extensions .cmd, .btm, .bat, .pl as well.

Starting OS/2 (and DOS) programs under Perl

This is what system() (see system), `` (seeI/O Operators in perlop), and open pipe (see open)are for. (Avoid exec() (see exec) unless you know what youdo).

Note however that to use some of these operators you need to have ash-syntax shell installed (see Pdksh, Frequently asked questions), and perl should be able to find it(see PERL_SH_DIR).

The cases when the shell is used are:

1

One-argument system() (see system), exec() (see exec)with redirection or shell meta-characters;

2

Pipe-open (see open) with the command which contains redirection or shell meta-characters;

3

Backticks `` (see I/O Operators in perlop) with the command which containsredirection or shell meta-characters;

4

If the executable called by system()/exec()/pipe-open()/`` is a scriptwith the "magic" #! line or extproc line which specifies shell;

5

If the executable called by system()/exec()/pipe-open()/`` is a scriptwithout "magic" line, and $ENV{EXECSHELL} is set to shell;

6

If the executable called by system()/exec()/pipe-open()/`` is notfound (is not this remark obsolete?);

7

For globbing (see glob, I/O Operators in perlop)(obsolete? Perl uses builtin globbing nowadays...).

For the sake of speed for a common case, in the above algorithms backslashes in the command name are not considered as shell metacharacters.

Perl starts scripts which begin with cookiesextproc or #! directly, without an intervention of shell. Perl uses thesame algorithm to find the executable as pdksh: if the pathon #! line does not work, and contains /, then the directorypart of the executable is ignored, and the executableis searched in . and on PATH. To find arguments for these scriptsPerl uses a different algorithm than pdksh: up to 3 arguments are recognized, and trailing whitespace is stripped.

If a scriptdoes not contain such a cooky, then to avoid calling sh.exe, Perl usesthe same algorithm as pdksh: if $ENV{EXECSHELL} is set, thescript is given as the first argument to this command, if not set, then$ENV{COMSPEC} /c is used (or a hardwired guess if $ENV{COMSPEC} isnot set).

When starting scripts directly, Perl uses exactly the same algorithm as for the search of script given by -S command-line option: it will look inthe current directory, then on components of $ENV{PATH} using the following order of appended extensions: no extension, .cmd, .btm, .bat, .pl.

Note that Perl will start to look for scripts only if OS/2 cannot start thespecified application, thus system 'blah' will not look for a script if there is an executable file blah.exe anywhere on PATH. Inother words, PATH is essentially searched twice: once by the OS foran executable, then by Perl for scripts.

Note also that executable files on OS/2 can have an arbitrary extension, but .exe will be automatically appended if no dot is present in the name. The workaround is as simple as that: since blah. and blah denote the same file (at list on FAT and HPFS file systems), to start an executable residing in file n:/bin/blah (no extension) give an argument n:/bin/blah. (dot appended) to system().

Perl will start PM programs from VIO (=text-mode) Perl process in aseparate PM session;the opposite is not true: when you start a non-PM program from a PMPerl process, Perl would not run it in a separate session. If a separatesession is desired, either ensurethat shell will be used, as in system 'cmd /c myprog', or start it usingoptional arguments to system() documented in OS2::Process module. Thisis considered to be a feature.

Frequently asked questions

"It does not work"

Perl binary distributions come with a testperl.cmd script which triesto detect common problems with misconfigured installations. There is apretty large chance it will discover which step of the installation youmanaged to goof. ;-)

I cannot run external programs

  • Did you run your programs with -w switch? See 2 (and DOS) programs under Perl in Starting OS.

  • Do you try to run internal shell commands, like `copy a b`(internal for cmd.exe), or `glob a*b` (internal for ksh)? Youneed to specify your shell explicitly, like `cmd /c copy a b`,since Perl cannot deduce which commands are internal to your shell.

I cannot embed perl into my program, or use perl.dll from myprogram.

  • Is your program EMX-compiled with -Zmt -Zcrtdll?

    Well, nowadays Perl DLL should be usable from a differently compiledprogram too... If you can run Perl code from REXX scripts (seeOS2::REXX), then there are some other aspect of interaction whichare overlooked by the current hackish code to supportdifferently-compiled principal programs.

    If everything else fails, you need to build a stand-alone DLL forperl. Contact me, I did it once. Sockets would not work, as a lot ofother stuff.

  • Did you use ExtUtils::Embed?

    Some time ago I had reports it does not work. Nowadays it is checkedin the Perl test suite, so grep ./t subdirectory of the build tree(as well as *.t files in the ./lib subdirectory) to find how itshould be done "correctly".

`` and pipe-open do not work under DOS.

This may a variant of just I cannot run external programs, or adeeper problem. Basically: you need RSX (see Prerequisites)for these commands to work, and you may need a port of sh.exe whichunderstands command arguments. One of such ports is listed inPrerequisites under RSX. Do not forget to set variablePERL_SH_DIR as well.

DPMI is required for RSX.

Cannot start find.exe "pattern" file

The whole idea of the "standard C API to start applications" is thatthe forms foo and "foo" of program arguments are completelyinterchangeable. find breaks this paradigm;

  1.   find "pattern" file
    2.  
  2.   find pattern file
    3.

are not equivalent; find cannot be started directly using the aboveAPI. One needs a way to surround the doublequotes in some otherquoting construction, necessarily having an extra non-Unixish shell inbetween.

Use one of

  1.   system 'cmd', '/c', 'find "pattern" file';
    2.  
  2.   `cmd /c 'find "pattern" file'`
    3.

This would start find.exe via cmd.exe via sh.exe viaperl.exe, but this is a price to pay if you want to usenon-conforming program.

INSTALLATION

Automatic binary installation

The most convenient way of installing a binary distribution of perl is via perl installerinstall.exe. Just follow the instructions, and 99% of theinstallation blues would go away.

Note however, that you need to have unzip.exe on your path, andEMX environment running. The latter means that if you justinstalled EMX, and made all the needed changes to Config.sys,you may need to reboot in between. Check EMX runtime by running

  1. emxrev
    2.

Binary installer also creates a folder on your desktop with some usefulobjects. If you need to change some aspects of the work of the binaryinstaller, feel free to edit the file Perl.pkg. This may be usefule.g., if you need to run the installer many times and do not want tomake many interactive changes in the GUI.

Things not taken care of by automatic binary installation:

  • PERL_BADLANG

    may be needed if you change your codepage after perl installation,and the new value is not supported by EMX. See PERL_BADLANG.

  • PERL_BADFREE

    see PERL_BADFREE.

  • Config.pm

    This file resides somewhere deep in the location you installed yourperl library, find it out by

    1.   perl -MConfig -le "print $INC{'Config.pm'}"
      2.

    While most important values in this file are updated by the binaryinstaller, some of them may need to be hand-edited. I know no suchdata, please keep me informed if you find one. Moreover, manualchanges to the installed version may need to be accompanied by an editof this file.

NOTE. Because of a typo the binary installer of 5.00305would install a variable PERL_SHPATH into Config.sys. Pleaseremove this variable and put PERL_SH_DIR instead.

Manual binary installation

As of version 5.00305, OS/2 perl binary distribution comes splitinto 11 components. Unfortunately, to enable configurable binaryinstallation, the file paths in the zip files are not absolute, butrelative to some directory.

Note that the extraction with the stored paths is still necessary(default with unzip, specify -d to pkunzip). However, youneed to know where to extract the files. You need also to manuallychange entries in Config.sys to reflect where did you put thefiles. Note that if you have some primitive unzipper (likepkunzip), you may get a lot of warnings/errors duringunzipping. Upgrade to (w)unzip.

Below is the sample of what to do to reproduce the configuration on mymachine. In VIEW.EXE you can press Ctrl-Insert now, andcut-and-paste from the resulting file - created in the directory youstarted VIEW.EXE from.

For each component, we mention environment variables related to eachinstallation directory. Either choose directories to match yourvalues of the variables, or create/append-to variables to take intoaccount the directories.

  • Perl VIO and PM executables (dynamically linked)
    1.   unzip perl_exc.zip *.exe *.ico -d f:/emx.add/bin
      2.  
    2.   unzip perl_exc.zip *.dll -d f:/emx.add/dll
      3.

    (have the directories with *.exe on PATH, and *.dll onLIBPATH);

  • Perl_ VIO executable (statically linked)
    1.   unzip perl_aou.zip -d f:/emx.add/bin
      2.

    (have the directory on PATH);

  • Executables for Perl utilities
    1.   unzip perl_utl.zip -d f:/emx.add/bin
      2.

    (have the directory on PATH);

  • Main Perl library
    1.   unzip perl_mlb.zip -d f:/perllib/lib
      2.

    If this directory is exactly the same as the prefix which was compiledinto perl.exe, you do not need to changeanything. However, for perl to find the library if you use a differentpath, you need toset PERLLIB_PREFIX in Config.sys, see PERLLIB_PREFIX.

  • Additional Perl modules
    1.   unzip perl_ste.zip -d f:/perllib/lib/site_perl/5.16.0/
      2.

    Same remark as above applies. Additionally, if this directory is notone of directories on @INC (and @INC is influenced by PERLLIB_PREFIX), youneed to put thisdirectory and subdirectory ./os2 in PERLLIB or PERL5LIBvariable. Do not use PERL5LIB unless you have it set already. SeeENVIRONMENT in perl.

    [Check whether this extraction directory is still applicable withthe new directory structure layout!]

  • Tools to compile Perl modules
    1.   unzip perl_blb.zip -d f:/perllib/lib
      2.

    Same remark as for perl_ste.zip.

  • Manpages for Perl and utilities
    1.   unzip perl_man.zip -d f:/perllib/man
      2.

    This directory should better be on MANPATH. You need to have aworking man to access these files.

  • Manpages for Perl modules
    1.   unzip perl_mam.zip -d f:/perllib/man
      2.

    This directory should better be on MANPATH. You need to have aworking man to access these files.

  • Source for Perl documentation
    1.   unzip perl_pod.zip -d f:/perllib/lib
      2.

    This is used by the perldoc program (see perldoc), and may be used togenerate HTML documentation usable by WWW browsers, anddocumentation in zillions of other formats: info, LaTeX,Acrobat, FrameMaker and so on. [Use programs such aspod2latex etc.]

  • Perl manual in .INF format
    1.   unzip perl_inf.zip -d d:/os2/book
      2.

    This directory should better be on BOOKSHELF.

  • Pdksh
    1.   unzip perl_sh.zip -d f:/bin
      2.

    This is used by perl to run external commands which explicitlyrequire shell, like the commands using redirection and shellmetacharacters. It is also used instead of explicit /bin/sh.

    Set PERL_SH_DIR (see PERL_SH_DIR) if you move sh.exe fromthe above location.

    Note. It may be possible to use some other sh-compatible shell (untested).

After you installed the components you needed and updated theConfig.sys correspondingly, you need to hand-editConfig.pm. This file resides somewhere deep in the location youinstalled your perl library, find it out by

  1.   perl -MConfig -le "print $INC{'Config.pm'}"
    2.

You need to correct all the entries which look like file paths (theycurrently start with f:/).

Warning

The automatic and manual perl installation leave precompiled pathsinside perl executables. While these paths are overwriteable (seePERLLIB_PREFIX, PERL_SH_DIR), some people may preferbinary editing of paths inside the executables/DLLs.

Accessing documentation

Depending on how you built/installed perl you may have (otherwiseidentical) Perl documentation in the following formats:

OS/2 .INF file

Most probably the most convenient form. Under OS/2 view it as

  1.   view perl
    2.  
  2.   view perl perlfunc
    3.  
  3.   view perl less
    4.  
  4.   view perl ExtUtils::MakeMaker
    5.

(currently the last two may hit a wrong location, but this may improvesoon). Under Win* see SYNOPSIS.

If you want to build the docs yourself, and have OS/2 toolkit, run

  1. pod2ipf > perl.ipf
    2.

in /perllib/lib/pod directory, then

  1. ipfc /inf perl.ipf
    2.

(Expect a lot of errors during the both steps.) Now move it on yourBOOKSHELF path.

Plain text

If you have perl documentation in the source form, perl utilitiesinstalled, and GNU groff installed, you may use

  1. perldoc perlfunc
    2.  
  2. perldoc less
    3.  
  3. perldoc ExtUtils::MakeMaker
    4.

to access the perl documentation in the text form (note that you may getbetter results using perl manpages).

Alternately, try running pod2text on .pod files.

Manpages

If you have man installed on your system, and you installed perlmanpages, use something like this:

  1. man perlfunc
    2.  
  2. man 3 less
    3.  
  3. man ExtUtils.MakeMaker
    4.

to access documentation for different components of Perl. Start with

  1. man perl
    2.

Note that dot (.) is used as a package separator for documentationfor packages, and as usual, sometimes you need to give the section - 3above - to avoid shadowing by the less(1) manpage.

Make sure that the directory above the directory with manpages ison our MANPATH, like this

  1.   set MANPATH=c:/man;f:/perllib/man
    2.

for Perl manpages in f:/perllib/man/man1/ etc.

HTML

If you have some WWW browser available, installed the Perldocumentation in the source form, and Perl utilities, you can buildHTML docs. Cd to directory with .pod files, and do like this

  1. cd f:/perllib/lib/pod
    2.  
  2. pod2html
    3.

After this you can direct your browser the file perl.html in thisdirectory, and go ahead with reading docs, like this:

  1. explore file:///f:/perllib/lib/pod/perl.html
    2.

Alternatively you may be able to get these docs prebuilt from CPAN.

GNU info files

Users of Emacs would appreciate it very much, especially withCPerl mode loaded. You need to get latest pod2texi from CPAN,or, alternately, the prebuilt info pages.

PDF files

for Acrobat are available on CPAN (may be for slightly older version ofperl).

LaTeX docs

can be constructed using pod2latex.

BUILD

Here we discuss how to build Perl under OS/2.

The short story

Assume that you are a seasoned porter, so are sure that all the necessarytools are already present on your system, and you know how to get the Perlsource distribution. Untar it, change to the extract directory, and

  1.   gnupatch -p0 < os2\diff.configure
    2.  
  2.   sh Configure -des -D prefix=f:/perllib
    3.  
  3.   make
    4.  
  4.   make test
    5.  
  5.   make install
    6.  
  6.   make aout_test
    7.  
  7.   make aout_install
    8.

This puts the executables in f:/perllib/bin. Manually move them to thePATH, manually move the built perl*.dll to LIBPATH (here forPerl DLL * is a not-very-meaningful hex checksum), and run

  1.   make installcmd INSTALLCMDDIR=d:/ir/on/path
    2.

Assuming that the man-files were put on an appropriate location,this completes the installation of minimal Perl system. (The binarydistribution contains also a lot of additional modules, and thedocumentation in INF format.)

What follows is a detailed guide through these steps.

Prerequisites

You need to have the latest EMX development environment, the fullGNU tool suite (gawk renamed to awk, and GNU find.exeearlier on path than the OS/2 find.exe, same with sort.exe, tocheck use

  1.   find --version
    2.  
  2.   sort --version
    3.

). You need the latest version of pdksh installed as sh.exe.

Check that you have BSD libraries and headers installed, and - optionally - Berkeley DB headers and libraries, and crypt.

Possible locations to get the files:

  1.   ftp://ftp.uni-heidelberg.de/pub/os2/unix/
    2.  
  2.   http://hobbes.nmsu.edu/h-browse.php?dir=/pub/os2
    3.  
  3.   http://cd.textfiles.com/hobbesos29804/disk1/DEV32/
    4.  
  4.   http://cd.textfiles.com/hobbesos29804/disk1/EMX09C/
    5.

It is reported that the following archives contain enough utils tobuild perl: gnufutil.zip, gnusutil.zip, gnututil.zip, gnused.zip,gnupatch.zip, gnuawk.zip, gnumake.zip, gnugrep.zip, bsddev.zip andksh527rt.zip (or a later version). Note that all these utilities areknown to be available from LEO:

  1.   ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/
    2.

Note also that the db.lib and db.a from the EMX distributionare not suitable for multi-threaded compile (even single-threadedflavor of Perl uses multi-threaded C RTL, forcompatibility with XFree86-OS/2). Get a corrected one from

  1.   http://www.ilyaz.org/software/os2/db_mt.zip
    2.

If you have exactly the same version of Perl installed already,make sure that no copies or perl are currently running. Later stepsof the build may fail since an older version of perl.dll loaded intomemory may be found. Running make test becomes meaningless, sincethe test are checking a previous build of perl (this situation is detectedand reported by lib/os2_base.t test). Do not forget to unsetPERL_EMXLOAD_SEC in environment.

Also make sure that you have /tmp directory on the current drive,and . directory in your LIBPATH. One may try to correct thelatter condition by

  1.   set BEGINLIBPATH .\.
    2.

if you use something like CMD.EXE or latest versions of4os2.exe. (Setting BEGINLIBPATH to just . is ignored by theOS/2 kernel.)

Make sure your gcc is good for -Zomf linking: run omflibsscript in /emx/lib directory.

Check that you have link386 installed. It comes standard with OS/2,but may be not installed due to customization. If typing

  1.   link386
    2.

shows you do not have it, do Selective install, and choose Linkobject modules in Optional system utilities/More. If you get intolink386 prompts, press Ctrl-C to exit.

Getting perl source

You need to fetch the latest perl source (including developersreleases). With some probability it is located in

  1.   http://www.cpan.org/src/
    2.  
  2.   http://www.cpan.org/src/unsupported
    3.

If not, you may need to dig in the indices to find it in the directoryof the current maintainer.

Quick cycle of developers release may break the OS/2 build time totime, looking into

  1.   http://www.cpan.org/ports/os2/
    2.

may indicate the latest release which was publicly released by themaintainer. Note that the release may include some additional patchesto apply to the current source of perl.

Extract it like this

  1.   tar vzxf perl5.00409.tar.gz
    2.

You may see a message about errors while extracting Configure. This isbecause there is a conflict with a similarly-named file configure.

Change to the directory of extraction.

Application of the patches

You need to apply the patches in ./os2/diff.* like this:

  1.   gnupatch -p0 < os2\diff.configure
    2.

You may also need to apply the patches supplied with the binarydistribution of perl. It also makes sense to look on theperl5-porters mailing list for the latest OS/2-related patches (seehttp://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/). Suchpatches usually contain strings /os2/ and patch, so it makessense looking for these strings.

Hand-editing

You may look into the file ./hints/os2.sh and correct anythingwrong you find there. I do not expect it is needed anywhere.

Making

  1.   sh Configure -des -D prefix=f:/perllib
    2.

prefix means: where to install the resulting perl library. Givingcorrect prefix you may avoid the need to specify PERLLIB_PREFIX,see PERLLIB_PREFIX.

Ignore the message about missing ln, and about -c option totr. The latter is most probably already fixed, if you see it and can tracewhere the latter spurious warning comes from, please inform me.

Now

  1.   make
    2.

At some moment the built may die, reporting a version mismatch orunable to run perl. This means that you do not have . inyour LIBPATH, so perl.exe cannot find the needed perl67B2.dll (treatthese hex digits as line noise). After this is fixed the buildshould finish without a lot of fuss.

Testing

Now run

  1.   make test
    2.

All tests should succeed (with some of them skipped). If you have thesame version of Perl installed, it is crucial that you have . earlyin your LIBPATH (or in BEGINLIBPATH), otherwise your tests will mostprobably test the wrong version of Perl.

Some tests may generate extra messages similar to

  • A lot of bad free

    in database tests related to Berkeley DB. This should be fixed already.If it persists, you may disable this warnings, see PERL_BADFREE.

  • Process terminated by SIGTERM/SIGINT

    This is a standard message issued by OS/2 applications. *nixapplications die in silence. It is considered to be a feature. One caneasily disable this by appropriate sighandlers.

    However the test engine bleeds these message to screen in unexpectedmoments. Two messages of this kind should be present duringtesting.

To get finer test reports, call

  1.   perl t/harness
    2.

The report with io/pipe.t failing may look like this:

  1.   Failed Test  Status Wstat Total Fail  Failed  List of failed
    2.  
  2.   ------------------------------------------------------------
    3.  
  3.   io/pipe.t 12 1   8.33%  9
    4.  
  4.   7 tests skipped, plus 56 subtests skipped.
    5.  
  5.   Failed 1/195 test scripts, 99.49% okay. 1/6542 subtests failed, 99.98% okay.
    6.

The reasons for most important skipped tests are:

  • op/fs.t
    18

    Checks atime and mtime of stat() - unfortunately, HPFSprovides only 2sec time granularity (for compatibility with FAT?).

    25

    Checks truncate() on a filehandle just opened for write - I do notknow why this should or should not work.

  • op/stat.t

    Checks stat(). Tests:

    4

    Checks atime and mtime of stat() - unfortunately, HPFSprovides only 2sec time granularity (for compatibility with FAT?).

Installing the built perl

If you haven't yet moved perl*.dll onto LIBPATH, do it now.

Run

  1.   make install
    2.

It would put the generated files into needed locations. Manually putperl.exe, perl__.exe and perl___.exe to a location on yourPATH, perl.dll to a location on your LIBPATH.

Run

  1.   make installcmd INSTALLCMDDIR=d:/ir/on/path
    2.

to convert perl utilities to .cmd files and put them onPATH. You need to put .EXE-utilities on path manually. They areinstalled in $prefix/bin, here $prefix is what you gave toConfigure, see Making.

If you use man, either move the installed */man/ directories toyour MANPATH, or modify MANPATH to match the location. (Onecould have avoided this by providing a correct manpath option to./Configure, or editing ./config.sh between configuring andmaking steps.)

a.out-style build

Proceed as above, but make perl_.exe (see perl_.exe) by

  1.   make perl_
    2.

test and install by

  1.   make aout_test
    2.  
  2.   make aout_install
    3.

Manually put perl_.exe to a location on your PATH.

Note. The build process for perl_ does not know about all thedependencies, so you should make sure that anything is up-to-date,say, by doing

  1.   make perl_dll
    2.

first.

Building a binary distribution

[This section provides a short overview only...]

Building should proceed differently depending on whether the version of perlyou install is already present and used on your system, or is a new versionnot yet used. The description below assumes that the version is new, soinstalling its DLLs and .pm files will not disrupt the operation of yoursystem even if some intermediate steps are not yet fully working.

The other cases require a little bit more convoluted procedures. Below Isuppose that the current version of Perl is 5.8.2, so the executables arenamed accordingly.

1.

Fully build and test the Perl distribution. Make sure that no tests arefailing with test and aout_test targets; fix the bugs in Perl andthe Perl test suite detected by these tests. Make sure that all_testmake target runs as clean as possible. Check that os2/perlrexx.cmdruns fine.

2.

Fully install Perl, including installcmd target. Copy the generated DLLsto LIBPATH; copy the numbered Perl executables (as in perl5.8.2.exe)to PATH; copy perl_.exe to PATH as perl_5.8.2.exe. Think whetheryou need backward-compatibility DLLs. In most cases you do not need to installthem yet; but sometime this may simplify the following steps.

3.

Make sure that CPAN.pm can download files from CPAN. If not, you may needto manually install Net::FTP.

4.

Install the bundle Bundle::OS2_default

  1.   perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_1
    2.

This may take a couple of hours on 1GHz processor (when run the first time).And this should not be necessarily a smooth procedure. Some modules may notspecify required dependencies, so one may need to repeat this procedure severaltimes until the results stabilize.

  1.   perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_2
    2.  
  2.   perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_3
    3.

Even after they stabilize, some tests may fail.

Fix as many discovered bugs as possible. Document all the bugs which are notfixed, and all the failures with unknown reasons. Inspect the produced logs00cpan_i_1 to find suspiciously skipped tests, and other fishy events.

Keep in mind that installation of some modules may fail too: for example,the DLLs to update may be already loaded by CPAN.pm. Inspect the installlogs (in the example above 00cpan_i_1 etc) for errors, and install thingsmanually, as in

  1.   cd $CPANHOME/.cpan/build/Digest-MD5-2.31
    2.  
  2.   make install
    3.

Some distributions may fail some tests, but you may want to install themanyway (as above, or via force install command of CPAN.pm shell-mode).

Since this procedure may take quite a long time to complete, it makes senseto "freeze" your CPAN configuration by disabling periodic updates of thelocal copy of CPAN index: set index_expire to some big value (I use 365),then save the settings

  1.   CPAN> o conf index_expire 365
    2.  
  2.   CPAN> o conf commit
    3.

Reset back to the default value 1 when you are finished.

5.

When satisfied with the results, rerun the installcmd target. Now youcan copy perl5.8.2.exe to perl.exe, and install the other OMF-buildexecutables: perl__.exe etc. They are ready to be used.

6.

Change to the ./pod directory of the build tree, download the Perl logoCamelGrayBig.BMP, and run

  1.   ( perl2ipf > perl.ipf ) |& tee 00ipf
    2.  
  2.   ipfc /INF perl.ipf |& tee 00inf
    3.

This produces the Perl docs online book perl.INF. Install in onBOOKSHELF path.

7.

Now is the time to build statically linked executable perl_.exe whichincludes newly-installed via Bundle::OS2_default modules. Doing testingvia CPAN.pm is going to be painfully slow, since it statically linksa new executable per XS extension.

Here is a possible workaround: create a toplevel Makefile.PL in$CPANHOME/.cpan/build/ with contents being (compare with Making executables with a custom collection of statically loaded extensions)

  1.   use ExtUtils::MakeMaker;
    2.  
  2.   WriteMakefile NAME => 'dummy';
    3.

execute this as

  1.   perl_5.8.2.exe Makefile.PL <nul |& tee 00aout_c1
    2.  
  2.   make -k all test <nul |& 00aout_t1
    3.

Again, this procedure should not be absolutely smooth. Some Makefile.PL'sin subdirectories may be buggy, and would not run as "child" scripts. Theinterdependency of modules can strike you; however, since non-XS modulesare already installed, the prerequisites of most modules have a very goodchance to be present.

If you discover some glitches, move directories of problematic modules to adifferent location; if these modules are non-XS modules, you may just ignorethem - they are already installed; the remaining, XS, modules you need toinstall manually one by one.

After each such removal you need to rerun the Makefile.PL/make process;usually this procedure converges soon. (But be sure to convert all thenecessary external C libraries from .lib format to .a format: run one of

  1.   emxaout foo.lib
    2.  
  2.   emximp -o foo.a foo.lib
    3.

whichever is appropriate.) Also, make sure that the DLLs for externallibraries are usable with with executables compiled without -Zmtd options.

When you are sure that only a few subdirectorieslead to failures, you may want to add -j4 option to make to speed upskipping subdirectories with already finished build.

When you are satisfied with the results of tests, install the build C librariesfor extensions:

  1.   make install |& tee 00aout_i
    2.

Now you can rename the file ./perl.exe generated during the last phaseto perl_5.8.2.exe; place it on PATH; if there is an inter-dependencybetween some XS modules, you may need to repeat the test/install loopwith this new executable and some excluded modules - until the procedureconverges.

Now you have all the necessary .a libraries for these Perl modules in theplaces where Perl builder can find it. Use the perl builder: change to anempty directory, create a "dummy" Makefile.PL again, and run

  1.   perl_5.8.2.exe Makefile.PL |& tee 00c
    2.  
  2.   make perl |& tee 00p
    3.

This should create an executable ./perl.exe with all the statically loadedextensions built in. Compare the generated perlmain.c files to make surethat during the iterations the number of loaded extensions only increases.Rename ./perl.exe to perl_5.8.2.exe on PATH.

When it converges, you got a functional variant of perl_5.8.2.exe; copy itto perl_.exe. You are done with generation of the local Perl installation.

8.

Make sure that the installed modules are actually installed in the locationof the new Perl, and are not inherited from entries of @INC given forinheritance from the older versions of Perl: set PERLLIB_582_PREFIX toredirect the new version of Perl to a new location, and copy the installedfiles to this new location. Redo the tests to make sure that the versions ofmodules inherited from older versions of Perl are not needed.

Actually, the log output of pod2ipf(1) during the step 6 gives a very detailedinfo about which modules are loaded from which place; so you may use it asan additional verification tool.

Check that some temporary files did not make into the perl install tree.Run something like this

  1.   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
    2.

in the install tree (both top one and sitelib one).

Compress all the DLLs with lxlite. The tiny .exe can be compressed with/c:max (the bug only appears when there is a fixup in the last 6 bytes of apage (?); since the tiny executables are much smaller than a page, the bugwill not hit). Do not compress perl_.exe - it would not work under DOS.

9.

Now you can generate the binary distribution. This is done by running thetest of the CPAN distribution OS2::SoftInstaller. Tune up the filetest.pl to suit the layout of current version of Perl first. Do notforget to pack the necessary external DLLs accordingly. Include thedescription of the bugs and test suite failures you could not fix. Includethe small-stack versions of Perl executables from Perl build directory.

Include perl5.def so that people can relink the perl DLL preservingthe binary compatibility, or can create compatibility DLLs. Include the difffiles (diff -pu old new) of fixes you did so that people can rebuild yourversion. Include perl5.map so that one can use remote debugging.

10.

Share what you did with the other people. Relax. Enjoy fruits of your work.

11.

Brace yourself for thanks, bug reports, hate mail and spam coming as resultof the previous step. No good deed should remain unpunished!

Building custom .EXE files

The Perl executables can be easily rebuilt at any moment. Moreover, one canuse the embedding interface (see perlembed) to make very customizedexecutables.

Making executables with a custom collection of statically loaded extensions

It is a little bit easier to do so while decreasing the list of staticallyloaded extensions. We discuss this case only here.

1.

Change to an empty directory, and create a placeholder <Makefile.PL>:

  1.   use ExtUtils::MakeMaker;
    2.  
  2.   WriteMakefile NAME => 'dummy';
    3.
2.

Run it with the flavor of Perl (perl.exe or perl_.exe) you want torebuild.

  1.   perl_ Makefile.PL
    2.
3.

Ask it to create new Perl executable:

  1.   make perl
    2.

(you may need to manually add PERLTYPE=-DPERL_CORE to this commandline onsome versions of Perl; the symptom is that the command-line globbing does notwork from OS/2 shells with the newly-compiled executable; check with

  1.   .\perl.exe -wle "print for @ARGV" *
    2.

).

4.

The previous step created perlmain.c which contains a list of newXS() callsnear the end. Removing unnecessary calls, and rerunning

  1.   make perl
    2.

will produce a customized executable.

Making executables with a custom search-paths

The default perl executable is flexible enough to support most usages.However, one may want something yet more flexible; for example, one may wantto find Perl DLL relatively to the location of the EXE file; or one may wantto ignore the environment when setting the Perl-library search patch, etc.

If you fill comfortable with embedding interface (see perlembed), suchthings are easy to do repeating the steps outlined in Making executables with a custom collection of statically loaded extensions, anddoing more comprehensive edits to main() of perlmain.c. The people withlittle desire to understand Perl can just rename main(), and do necessarymodification in a custom main() which calls the renamed function in appropriatetime.

However, there is a third way: perl DLL exports the main() function and severalcallbacks to customize the search path. Below is a complete example of a"Perl loader" which

1.

Looks for Perl DLL in the directory $exedir/../dll;

2.

Prepends the above directory to BEGINLIBPATH;

3.

Fails if the Perl DLL found via BEGINLIBPATH is different from what wasloaded on step 1; e.g., another process could have loaded it from LIBPATHor from a different value of BEGINLIBPATH. In these cases one needs tomodify the setting of the system so that this other process either does notrun, or loads the DLL from BEGINLIBPATH with LIBPATHSTRICT=T (availablewith kernels after September 2000).

4.

Loads Perl library from $exedir/../dll/lib/.

5.

Uses Bourne shell from $exedir/../dll/sh/ksh.exe.

For best results compile the C file below with the same options as the PerlDLL. However, a lot of functionality will work even if the executable is notan EMX applications, e.g., if compiled with

  1.   gcc -Wall -DDOSISH -DOS2=1 -O2 -s -Zomf -Zsys perl-starter.c -DPERL_DLL_BASENAME=\"perl312F\" -Zstack 8192 -Zlinker /PM:VIO
    2.

Here is the sample C file:

  1.   #define INCL_DOS
    2.  
  2.   #define INCL_NOPM
    3.  
  3.   /* These are needed for compile if os2.h includes os2tk.h, not os2emx.h */
    4.  
  4.   #define INCL_DOSPROCESS
    5.  
  5.   #include <os2.h>
    6.  
  6.  
  7.   #include "EXTERN.h"
    8.  
  8.   #define PERL_IN_MINIPERLMAIN_C
    9.  
  9.   #include "perl.h"
    10.  
  10.  
  11.   static char *me;
    12.  
  12.   HMODULE handle;
    13.  
  13.  
  14.   static void
    15.  
  15.   die_with(char *msg1, char *msg2, char *msg3, char *msg4)
    16.  
  16.   {
    17.  
  17.  ULONG c;
    18.  
  18.  char *s = " error: "
    19.  
  19.  
  20.   DosWrite(2, me, strlen(me), &c);
    21.  
  21.   DosWrite(2, s, strlen(s), &c);
    22.  
  22.   DosWrite(2, msg1, strlen(msg1), &c);
    23.  
  23.   DosWrite(2, msg2, strlen(msg2), &c);
    24.  
  24.   DosWrite(2, msg3, strlen(msg3), &c);
    25.  
  25.   DosWrite(2, msg4, strlen(msg4), &c);
    26.  
  26.   DosWrite(2, "\r\n", 2, &c);
    27.  
  27.   exit(255);
    28.  
  28.     }
    29.  
  29.  
  30.     typedef ULONG (*fill_extLibpath_t)(int type, char *pre, char *post, int replace, char *msg);
    31.  
  31.     typedef int (*main_t)(int type, char *argv[], char *env[]);
    32.  
  32.     typedef int (*handler_t)(void* data, int which);
    33.  
  33.  
  34.     #ifndef PERL_DLL_BASENAME
    35.  
  35.     #  define PERL_DLL_BASENAME "perl"
    36.  
  36.     #endif
    37.  
  37.  
  38.     static HMODULE
    39.  
  39.     load_perl_dll(char *basename)
    40.  
  40.     {
    41.  
  41.     char buf[300], fail[260];
    42.  
  42.     STRLEN l, dirl;
    43.  
  43.     fill_extLibpath_t f;
    44.  
  44.     ULONG rc_fullname;
    45.  
  45.     HMODULE handle, handle1;
    46.  
  46.  
  47.     if (_execname(buf, sizeof(buf) - 13) != 0)
    48.  
  48.     die_with("Can't find full path: ", strerror(errno), "", "");
    49.  
  49.     /* XXXX Fill 'me' with new value */
    50.  
  50.     l = strlen(buf);
    51.  
  51.   while (l && buf[l-1] != '/' && buf[l-1] != '\')
    52.  
  52.   l--;
    53.  
  53.   dirl = l - 1;
    54.  
  54.   strcpy(buf + l, basename);
    55.  
  55.   l += strlen(basename);
    56.  
  56.   strcpy(buf + l, ".dll");
    57.  
  57.   if ( (rc_fullname = DosLoadModule(fail, sizeof fail, buf, &handle)) != 0
    58.  
  58.    && DosLoadModule(fail, sizeof fail, basename, &handle) != 0 )
    59.  
  59.   die_with("Can't load DLL ", buf, "", "");
    60.  
  60.   if (rc_fullname)
    61.  
  61.   return handle;/* was loaded with short name; all is fine */
    62.  
  62.   if (DosQueryProcAddr(handle, 0, "fill_extLibpath", (PFN*)&f))
    63.  
  63.   die_with(buf, ": DLL exports no symbol ", "fill_extLibpath", "");
    64.  
  64.   buf[dirl] = 0;
    65.  
  65.   if (f(0 /*BEGINLIBPATH*/, buf /* prepend */, NULL /* append */,
    66.  
  66.   0 /* keep old value */, me))
    67.  
  67.     die_with(me, ": prepending BEGINLIBPATH", "", "");
    68.  
  68.     if (DosLoadModule(fail, sizeof fail, basename, &handle1) != 0)
    69.  
  69.     die_with(me, ": finding perl DLL again via BEGINLIBPATH", "", "");
    70.  
  70.     buf[dirl] = '\' 
    71.  
  71.     if (handle1 != handle) {
    72.  
  72.     if (DosQueryModuleName(handle1, sizeof(fail), fail))
    73.  
  73.     strcpy(fail, "???");
    74.  
  74.     die_with(buf, ":\n\tperl DLL via BEGINLIBPATH is different: \n\t",
    75.  
  75.       fail,
    76.  
  76.       "\n\tYou may need to manipulate global BEGINLIBPATH and LIBPATHSTRICT"
    77.  
  77.       "\n\tso that the other copy is loaded via BEGINLIBPATH.");
    78.  
  78.     }
    79.  
  79.     return handle;
    80.  
  80.     }
    81.  
  81.  
  82.     int
    83.  
  83.     main(int argc, char **argv, char **env)
    84.  
  84.     {
    85.  
  85.     main_t f;
    86.  
  86.     handler_t h;
    87.  
  87.  
  88.     me = argv[0];
    89.  
  89.     /**/
    90.  
  90.     handle = load_perl_dll(PERL_DLL_BASENAME);
    91.  
  91.  
  92.     if (DosQueryProcAddr(handle, 0, "Perl_OS2_handler_install", (PFN*)&h))
    93.  
  93.     die_with(PERL_DLL_BASENAME, ": DLL exports no symbol ", "Perl_OS2_handler_install", "");
    94.  
  94.     if ( !h((void *)"~installprefix", Perlos2_handler_perllib_from)
    95.  
  95.       || !h((void *)"~dll", Perlos2_handler_perllib_to)
    96.  
  96.       || !h((void *)"~dll/sh/ksh.exe", Perlos2_handler_perl_sh) )
    97.  
  97.     die_with(PERL_DLL_BASENAME, ": Can't install @INC manglers", "", "");
    98.  
  98.  
  99.     if (DosQueryProcAddr(handle, 0, "dll_perlmain", (PFN*)&f))
    100.  
  100.     die_with(PERL_DLL_BASENAME, ": DLL exports no symbol ", "dll_perlmain", "");
    101.  
  101.     return f(argc, argv, env);
    102.  
  102.     }
    103.

Build FAQ

Some / became \ in pdksh.

You have a very old pdksh. See Prerequisites.

'errno' - unresolved external

You do not have MT-safe db.lib. See Prerequisites.

Problems with tr or sed

reported with very old version of tr and sed.

Some problem (forget which ;-)

You have an older version of perl.dll on your LIBPATH, whichbroke the build of extensions.

Library ... not found

You did not run omflibs. See Prerequisites.

Segfault in make

You use an old version of GNU make. See Prerequisites.

op/sprintf test failure

This can result from a bug in emx sprintf which was fixed in 0.9d fix 03.

Specific (mis)features of OS/2 port

setpriority, getpriority

Note that these functions are compatible with *nix, not with the olderports of '94 - 95. The priorities are absolute, go from 32 to -95,lower is quicker. 0 is the default priority.

WARNING. Calling getpriority on a non-existing process could lockthe system before Warp3 fixpak22. Starting with Warp3, Perl will usea workaround: it aborts getpriority() if the process is not present.This is not possible on older versions 2.*, and has a racecondition anyway.

system()

Multi-argument form of system() allows an additional numericargument. The meaning of this argument is described inOS2::Process.

When finding a program to run, Perl first asks the OS to look for executableson PATH (OS/2 adds extension .exe if no extension is present).If not found, it looks for a script with possible extensions added in this order: no extension, .cmd, .btm, .bat, .pl. If found, Perl checks the start of the file for magicstrings "#!" and "extproc ". If found, Perl uses the rest of thefirst line as the beginning of the command line to run this script. Theonly mangling done to the first line is extraction of arguments (currentlyup to 3), and ignoring of the path-part of the "interpreter" name if it can'tbe found using the full path.

E.g., system 'foo', 'bar', 'baz' may lead Perl to findingC:/emx/bin/foo.cmd with the first line being

  1.  extproc /bin/bash -x   -c
    2.

If /bin/bash.exe is not found, then Perl looks for an executable bash.exe onPATH. If found in C:/emx.add/bin/bash.exe, then the above system() istranslated to

  1.   system qw(C:/emx.add/bin/bash.exe -x -c C:/emx/bin/foo.cmd bar baz)
    2.

One additional translation is performed: instead of /bin/sh Perl usesthe hardwired-or-customized shell (see PERL_SH_DIR).

The above search for "interpreter" is recursive: if bash executable is notfound, but bash.btm is found, Perl will investigate its first line etc.The only hardwired limit on the recursion depth is implicit: there is a limit4 on the number of additional arguments inserted before the actual argumentsgiven to system(). In particular, if no additional arguments are specifiedon the "magic" first lines, then the limit on the depth is 4.

If Perl finds that the found executable is of PM type when thecurrent session is not, it will start the new process in a separate session ofnecessary type. Call via OS2::Process to disable this magic.

WARNING. Due to the described logic, you need to explicitlyspecify .com extension if needed. Moreover, if the executableperl5.6.1 is requested, Perl will not look for perl5.6.1.exe.[This may change in the future.]

extproc on the first line

If the first chars of a Perl script are "extproc ", this line is treatedas #!-line, thus all the switches on this line are processed (twiceif script was started via cmd.exe). See DESCRIPTION in perlrun.

Additional modules:

OS2::Process, OS2::DLL, OS2::REXX, OS2::PrfDB, OS2::ExtAttr. Thesemodules provide access to additional numeric argument for systemand to the information about the running process,to DLLs having functions with REXX signature and to the REXX runtime, toOS/2 databases in the .INI format, and to Extended Attributes.

Two additional extensions by Andreas Kaiser, OS2::UPM, andOS2::FTP, are included into ILYAZ directory, mirrored on CPAN.Other OS/2-related extensions are available too.

Prebuilt methods:

  • File::Copy::syscopy

    used by File::Copy::copy, see File::Copy.

  • DynaLoader::mod2fname

    used by DynaLoader for DLL name mangling.

  • Cwd::current_drive()

    Self explanatory.

  • Cwd::sys_chdir(name)

    leaves drive as it is.

  • Cwd::change_drive(name)

    changes the "current" drive.

  • Cwd::sys_is_absolute(name)

    means has drive letter and is_rooted.

  • Cwd::sys_is_rooted(name)

    means has leading [/\] (maybe after a drive-letter:).

  • Cwd::sys_is_relative(name)

    means changes with current dir.

  • Cwd::sys_cwd(name)

    Interface to cwd from EMX. Used by Cwd::cwd.

  • Cwd::sys_abspath(name, dir)

    Really really odious function to implement. Returns absolute name offile which would have name if CWD were dir. Dir defaults to thecurrent dir.

  • Cwd::extLibpath([type])

    Get current value of extended library search path. If type ispresent and positive, works with END_LIBPATH, if negative, workswith LIBPATHSTRICT, otherwise with BEGIN_LIBPATH.

  • Cwd::extLibpath_set( path [, type ] )

    Set current value of extended library search path. If type ispresent and positive, works with <END_LIBPATH>, if negative, workswith LIBPATHSTRICT, otherwise with BEGIN_LIBPATH.

  • OS2::Error(do_harderror,do_exception)

    Returnsundef if it was not called yet, otherwise bit 1 isset if on the previous call do_harderror was enabled, bit2 is set if on previous call do_exception was enabled.

    This function enables/disables error popups associated with hardware errors (Disk not ready etc.) and software exceptions.

    I know of no way to find out the state of popups before the first callto this function.

  • OS2::Errors2Drive(drive)

    Returns undef if it was not called yet, otherwise return false if errorswere not requested to be written to a hard drive, or the drive letter ifthis was requested.

    This function may redirect error popups associated with hardware errors(Disk not ready etc.) and software exceptions to the file POPUPLOG.OS2 atthe root directory of the specified drive. Overrides OS2::Error() specifiedby individual programs. Given argument undef will disable redirection.

    Has global effect, persists after the application exits.

    I know of no way to find out the state of redirection of popups to the diskbefore the first call to this function.

  • OS2::SysInfo()

    Returns a hash with system information. The keys of the hash are

    1. MAX_PATH_LENGTH, MAX_TEXT_SESSIONS, MAX_PM_SESSIONS,
      2.  
    2. MAX_VDM_SESSIONS, BOOT_DRIVE, DYN_PRI_VARIATION,
      3.  
    3. MAX_WAIT, MIN_SLICE, MAX_SLICE, PAGE_SIZE,
      4.  
    4. VERSION_MAJOR, VERSION_MINOR, VERSION_REVISION,
      5.  
    5. MS_COUNT, TIME_LOW, TIME_HIGH, TOTPHYSMEM, TOTRESMEM,
      6.  
    6. TOTAVAILMEM, MAXPRMEM, MAXSHMEM, TIMER_INTERVAL,
      7.  
    7. MAX_COMP_LENGTH, FOREGROUND_FS_SESSION,
      8.  
    8. FOREGROUND_PROCESS
      9.
  • OS2::BootDrive()

    Returns a letter without colon.

  • OS2::MorphPM(serve), OS2::UnMorphPM(serve)

    Transforms the current application into a PM application and back.The argument true means that a real message loop is going to be served.OS2::MorphPM() returns the PM message queue handle as an integer.

    See Centralized management of resources for additional details.

  • OS2::Serve_Messages(force)

    Fake on-demand retrieval of outstanding PM messages. If force is false,will not dispatch messages if a real message loop is known tobe present. Returns number of messages retrieved.

    Dies with "QUITing..." if WM_QUIT message is obtained.

  • OS2::Process_Messages(force [, cnt])

    Retrieval of PM messages until window creation/destruction. If force is false, will not dispatch messages if a real message loopis known to be present.

    Returns change in number of windows. If cnt is given,it is incremented by the number of messages retrieved.

    Dies with "QUITing..." if WM_QUIT message is obtained.

  • OS2::_control87(new,mask)

    the same as _control87(3) of EMX. Takes integers as arguments, returnsthe previous coprocessor control word as an integer. Only bits in new whichare present in mask are changed in the control word.

  • OS2::get_control87()

    gets the coprocessor control word as an integer.

  • OS2::set_control87_em(new=MCW_EM,mask=MCW_EM)

    The variant of OS2::_control87() with default values good forhandling exception mask: if no mask, uses exception mask part of newonly. If no new, disables all the floating point exceptions.

    See Misfeatures for details.

  • OS2::DLLname([how [, \&xsub]])

    Gives the information about the Perl DLL or the DLL containing the Cfunction bound to by &xsub. The meaning of how is: default (2):full name; 0: handle; 1: module name.

(Note that some of these may be moved to different libraries -eventually).

Prebuilt variables:

  • $OS2::emx_rev

    numeric value is the same as _emx_rev of EMX, a string value the sameas _emx_vprt (similar to 0.9c).

  • $OS2::emx_env

    same as _emx_env of EMX, a number similar to 0x8001.

  • $OS2::os_ver

    a number OS_MAJOR + 0.001 * OS_MINOR.

  • $OS2::is_aout

    true if the Perl library was compiled in AOUT format.

  • $OS2::can_fork

    true if the current executable is an AOUT EMX executable, so Perl canfork. Do not use this, use the portable check for$Config::Config{dfork}.

  • $OS2::nsyserror

    This variable (default is 1) controls whether to enforce the contentsof $^E to start with SYS0003-like id. If set to 0, then the stringvalue of $^E is what is available from the OS/2 message file. (Somemessages in this file have an SYS0003-like id prepended, some not.)

Misfeatures

  • Since flock(3) is present in EMX, but is not functional, it is emulated by perl. To disable the emulations, set environment variableUSE_PERL_FLOCK=0.

  • Here is the list of things which may be "broken" onEMX (from EMX docs):

    • The functions recvmsg(3), sendmsg(3), and socketpair(3) are notimplemented.

    • sock_init(3) is not required and not implemented.

    • flock(3) is not yet implemented (dummy function). (Perl has a workaround.)

    • kill(3): Special treatment of PID=0, PID=1 and PID=-1 is not implemented.

    • waitpid(3):

      1.   WUNTRACED
        2.  
      2.   Not implemented.
        3.  
      3.   waitpid() is not implemented for negative values of PID.
        4.

    Note that kill -9 does not work with the current version of EMX.

  • See Text-mode filehandles.

  • Unix-domain sockets on OS/2 live in a pseudo-file-system /sockets/....To avoid a failure to create a socket with a name of a different form,"/socket/" is prepended to the socket name (unless it starts with thisalready).

    This may lead to problems later in case the socket is accessed via the"usual" file-system calls using the "initial" name.

  • Apparently, IBM used a compiler (for some period of time around '95?) whichchanges FP mask right and left. This is not that bad for IBM'sprograms, but the same compiler was used for DLLs which are used withgeneral-purpose applications. When these DLLs are used, the state offloating-point flags in the application is not predictable.

    What is much worse, some DLLs change the floating point flags when in_DLLInitTerm() (e.g., TCP32IP). This means that even if you do not callany function in the DLL, just the act of loading this DLL will reset yourflags. What is worse, the same compiler was used to compile some HOOK DLLs.Given that HOOK dlls are executed in the context of all the applicationsin the system, this means a complete unpredictability of floating pointflags on systems using such HOOK DLLs. E.g., GAMESRVR.DLL of DIVEorigin changes the floating point flags on each write to the TTY of a VIO(windowed text-mode) applications.

    Some other (not completely debugged) situations when FP flags change includesome video drivers (?), and some operations related to creation of the windows.People who code OpenGL may have more experience on this.

    Perl is generally used in the situation when all the floating-pointexceptions are ignored, as is the default under EMX. If they are not ignored,some benign Perl programs would get a SIGFPE and would die a horrible death.

    To circumvent this, Perl uses two hacks. They help against one type ofdamage only: FP flags changed when loading a DLL.

    One of the hacks is to disable floating point exceptions on Perl startup (asis the default with EMX). This helps only with compile-time-linked DLLschanging the flags before main() had a chance to be called.

    The other hack is to restore FP flags after a call to dlopen(). This helpsagainst similar damage done by DLLs _DLLInitTerm() at runtime. Currentlyno way to switch these hacks off is provided.

Modifications

Perl modifies some standard C library calls in the following ways:

  • popen

    my_popen uses sh.exe if shell is required, cf. PERL_SH_DIR.

  • tmpnam

    is created using TMP or TEMP environment variable, viatempnam.

  • tmpfile

    If the current directory is not writable, file is created using modifiedtmpnam, so there may be a race condition.

  • ctermid

    a dummy implementation.

  • stat

    os2_stat special-cases /dev/tty and /dev/con.

  • mkdir, rmdir

    these EMX functions do not work if the path contains a trailing /.Perl contains a workaround for this.

  • flock

    Since flock(3) is present in EMX, but is not functional, it is emulated by perl. To disable the emulations, set environment variableUSE_PERL_FLOCK=0.

Identifying DLLs

All the DLLs built with the current versions of Perl have ID stringsidentifying the name of the extension, its version, and the versionof Perl required for this DLL. Run bldlevel DLL-name to find thisinfo.

Centralized management of resources

Since to call certain OS/2 API one needs to have a correctly initializedWin subsystem, OS/2-specific extensions may require getting HABs andHMQs. If an extension would do it on its own, another extension couldfail to initialize.

Perl provides a centralized management of these resources:

  • HAB

    To get the HAB, the extension should call hab = perl_hab_GET() in C. Afterthis call is performed, hab may be accessed as Perl_hab. There isno need to release the HAB after it is used.

    If by some reasons perl.h cannot be included, use

    1.   extern int Perl_hab_GET(void);
      2.

    instead.

  • HMQ

    There are two cases:

    • the extension needs an HMQ only because some API will not work otherwise.Use serve = 0 below.

    • the extension needs an HMQ since it wants to engage in a PM event loop.Use serve = 1 below.

    To get an HMQ, the extension should call hmq = perl_hmq_GET(serve) in C.After this call is performed, hmq may be accessed as Perl_hmq.

    To signal to Perl that HMQ is not needed any more, callperl_hmq_UNSET(serve). Perl process will automatically morph/unmorph itselfinto/from a PM process if HMQ is needed/not-needed. Perl will automaticallyenable/disable WM_QUIT message during shutdown if the message queue isserved/not-served.

    NOTE. If during a shutdown there is a message queue which did not disableWM_QUIT, and which did not process the received WM_QUIT message, theshutdown will be automatically cancelled. Do not call perl_hmq_GET(1)unless you are going to process messages on an orderly basis.

  • Treating errors reported by OS/2 API

    There are two principal conventions (it is useful to call them Dos*and Win* - though this part of the function signature is not alwaysdetermined by the name of the API) of reporting the error conditionsof OS/2 API. Most of Dos* APIs report the error code as the resultof the call (so 0 means success, and there are many types of errors).Most of Win* API report success/fail via the result beingTRUE/FALSE; to find the reason for the failure one should callWinGetLastError() API.

    Some Win* entry points also overload a "meaningful" return valuewith the error indicator; having a 0 return value indicates an error.Yet some other Win* entry points overload things even more, and 0return value may mean a successful call returning a valid value 0, aswell as an error condition; in the case of a 0 return value one shouldcall WinGetLastError() API to distinguish a successful call from afailing one.

    By convention, all the calls to OS/2 API should indicate theirfailures by resetting $^E. All the Perl-accessible functions whichcall OS/2 API may be broken into two classes: some die()s when an APIerror is encountered, the other report the error via a false returnvalue (of course, this does not concern Perl-accessible functionswhich expect a failure of the OS/2 API call, having some workaroundscoded).

    Obviously, in the situation of the last type of the signature of an OS/2API, it is must more convenient for the users if the failure isindicated by die()ing: one does not need to check $^E to know thatsomething went wrong. If, however, this solution is not desirable bysome reason, the code in question should reset $^E to 0 before makingthis OS/2 API call, so that the caller of this Perl-accessiblefunction has a chance to distinguish a success-but-0-return value froma failure. (One may return undef as an alternative way of reportingan error.)

    The macros to simplify this type of error propagation are

    • CheckOSError(expr)

      Returns true on error, sets $^E. Expects expr() be a call ofDos*-style API.

    • CheckWinError(expr)

      Returns true on error, sets $^E. Expects expr() be a call ofWin*-style API.

    • SaveWinError(expr)

      Returns expr, sets $^E from WinGetLastError() if expr is false.

    • SaveCroakWinError(expr,die,name1,name2)

      Returns expr, sets $^E from WinGetLastError() if expr is false,and die()s if die and $^E are true. The message to die is theconcatenated strings name1 and name2, separated by ": " fromthe contents of $^E.

    • WinError_2_Perl_rc

      Sets Perl_rc to the return value of WinGetLastError().

    • FillWinError

      Sets Perl_rc to the return value of WinGetLastError(), and sets $^Eto the corresponding value.

    • FillOSError(rc)

      Sets Perl_rc to rc, and sets $^E to the corresponding value.

  • Loading DLLs and ordinals in DLLs

    Some DLLs are only present in some versions of OS/2, or in someconfigurations of OS/2. Some exported entry points are present onlyin DLLs shipped with some versions of OS/2. If these DLLs and entrypoints were linked directly for a Perl executable/DLL or from a Perlextensions, this binary would work only with the specifiedversions/setups. Even if these entry points were not needed, theload of the executable (or DLL) would fail.

    For example, many newer useful APIs are not present in OS/2 v2; manyPM-related APIs require DLLs not available on floppy-boot setup.

    To make these calls fail only when the calls are executed, oneshould call these API via a dynamic linking API. There is a subsystemin Perl to simplify such type of calls. A large number of entrypoints available for such linking is provided (see entries_ordinals- and also PMWIN_entries - in os2ish.h). These ordinals can beaccessed via the APIs:

    1.   CallORD(), DeclFuncByORD(), DeclVoidFuncByORD(),
      2.  
    2.   DeclOSFuncByORD(), DeclWinFuncByORD(), AssignFuncPByORD(),
      3.  
    3.   DeclWinFuncByORD_CACHE(), DeclWinFuncByORD_CACHE_survive(),
      4.  
    4.   DeclWinFuncByORD_CACHE_resetError_survive(),
      5.  
    5.   DeclWinFunc_CACHE(), DeclWinFunc_CACHE_resetError(),
      6.  
    6.   DeclWinFunc_CACHE_survive(), DeclWinFunc_CACHE_resetError_survive()
      7.

    See the header files and the C code in the supplied OS/2-relatedmodules for the details on usage of these functions.

    Some of these functions also combine dynaloading semantic with theerror-propagation semantic discussed above.

Perl flavors

Because of idiosyncrasies of OS/2 one cannot have all the eggs in thesame basket (though EMX environment tries hard to overcome thislimitations, so the situation may somehow improve). There are 4executables for Perl provided by the distribution:

perl.exe

The main workhorse. This is a chimera executable: it is compiled as ana.out-style executable, but is linked with omf-style dynamiclibrary perl.dll, and with dynamic CRT DLL. This executable is aVIO application.

It can load perl dynamic extensions, and it can fork().

Note. Keep in mind that fork() is needed to open a pipe to yourself.

perl_.exe

This is a statically linked a.out-style executable. It cannotload dynamic Perl extensions. The executable supplied in binarydistributions has a lot of extensions prebuilt, thus the above restriction is important only if you use custom-built extensions. This executable is a VIOapplication.

This is the only executable with does not require OS/2. Thefriends locked into M$ world would appreciate the fact that thisexecutable runs under DOS, Win0.3*, Win0.95 and WinNT with anappropriate extender. See Other OSes.

perl__.exe

This is the same executable as perl___.exe, but it is a PMapplication.

Note. Usually (unless explicitly redirected during the startup)STDIN, STDERR, and STDOUT of a PMapplication are redirected to nul. However, it is possible to seethem if you start perl__.exe from a PM program which emulates aconsole window, like Shell mode of Emacs or EPM. Thus it ispossible to use Perl debugger (see perldebug) to debug your PMapplication (but beware of the message loop lockups - this will notwork if you have a message queue to serve, unless you hook the servinginto the getc() function of the debugger).

Another way to see the output of a PM program is to run it as

  1.   pm_prog args 2>&1 | cat -
    2.

with a shell different from cmd.exe, so that it does not createa link between a VIO session and the session of pm_porg. (Such a linkcloses the VIO window.) E.g., this works with sh.exe - or with Perl!

  1.   open P, 'pm_prog args 2>&1 |' or die;
    2.  
  2.   print while <P>;
    3.

The flavor perl__.exe is required if you want to start your program withouta VIO window present, but not detached (run help detach for more info).Very useful for extensions which use PM, like Perl/Tk or OpenGL.

Note also that the differences between PM and VIO executables are onlyin the default behaviour. One can start any executable inany kind of session by using the arguments /fs, /pm or/win switches of the command start (of CMD.EXE or a similarshell). Alternatively, one can use the numeric first argument of thesystem Perl function (see OS2::Process).

perl___.exe

This is an omf-style executable which is dynamically linked toperl.dll and CRT DLL. I know no advantages of this executableover perl.exe, but it cannot fork() at all. Well, one advantage isthat the build process is not so convoluted as with perl.exe.

It is a VIO application.

Why strange names?

Since Perl processes the #!-line (cf. DESCRIPTION in perlrun, Command Switches in perlrun,No Perl script found in input in perldiag), it should know when aprogram is a Perl. There is some naming convention which allowsPerl to distinguish correct lines from wrong ones. The above names arealmost the only names allowed by this convention which do not containdigits (which have absolutely different semantics).

Why dynamic linking?

Well, having several executables dynamically linked to the same hugelibrary has its advantages, but this would not substantiate theadditional work to make it compile. The reason is the complicated-to-developersbut very quick and convenient-to-users "hard" dynamic linking used by OS/2.

There are two distinctive features of the dyna-linking model of OS/2:first, all the references to external functions are resolved at the compile time;second, there is no runtime fixup of the DLLs after they are loaded into memory.The first feature is an enormous advantage over other models: it avoidsconflicts when several DLLs used by an application export entries withthe same name. In such cases "other" models of dyna-linking just choosebetween these two entry points using some random criterion - with predictabledisasters as results. But it is the second feature which requires the buildof perl.dll.

The address tables of DLLs are patched only once, when they areloaded. The addresses of the entry points into DLLs are guaranteed to bethe same for all the programs which use the same DLL. This removes theruntime fixup - once DLL is loaded, its code is read-only.

While this allows some (significant?) performance advantages, this makes lifemuch harder for developers, since the above scheme makes it impossiblefor a DLL to be "linked" to a symbol in the .EXE file. Indeed, thiswould need a DLL to have different relocations tables for the(different) executables which use this DLL.

However, a dynamically loaded Perl extension is forced to use some symbolsfrom the perlexecutable, e.g., to know how to find the arguments to the functions:the arguments live on the perlinternal evaluation stack. The solution is to put the main code ofthe interpreter into a DLL, and make the .EXE file which just loadsthis DLL into memory and supplies command-arguments. The extension DLLcannot link to symbols in .EXE, but it has no problem linkingto symbols in the .DLL.

This greatly increases the load time for the application (as well ascomplexity of the compilation). Since interpreter is in a DLL,the C RTL is basically forced to reside in a DLL as well (otherwiseextensions would not be able to use CRT). There are some advantages ifyou use different flavors of perl, such as running perl.exe andperl__.exe simultaneously: they share the memory of perl.dll.

NOTE. There is one additional effect which makes DLLs more wasteful:DLLs are loaded in the shared memory region, which is a scarse resourcegiven the 512M barrier of the "standard" OS/2 virtual memory. The code of.EXE files is also shared by all the processes which use the particular.EXE, but they are "shared in the private address space of the process";this is possible because the address at which different sectionsof the .EXE file are loaded is decided at compile-time, thus all theprocesses have these sections loaded at same addresses, and no fixupof internal links inside the .EXE is needed.

Since DLLs may be loaded at run time, to have the same mechanism for DLLsone needs to have the address range of any of the loaded DLLs in thesystem to be available in all the processes which did not load a particularDLL yet. This is why the DLLs are mapped to the shared memory region.

Why chimera build?

Current EMX environment does not allow DLLs compiled using Unixisha.out format to export symbols for data (or at least some types ofdata). This forces omf-style compile of perl.dll.

Current EMX environment does not allow .EXE files compiled inomf format to fork(). fork() is needed for exactly three Perloperations:

  • explicit fork() in the script,

  • open FH, "|-"

  • open FH, "-|", in other words, opening pipes to itself.

While these operations are not questions of life and death, they areneeded for a lot ofuseful scripts. This forces a.out-style compile ofperl.exe.

ENVIRONMENT

Here we list environment variables with are either OS/2- and DOS- andWin*-specific, or are more important under OS/2 than under other OSes.

PERLLIB_PREFIX

Specific for EMX port. Should have the form

  1.   path1;path2
    2.

or

  1.   path1 path2
    2.

If the beginning of some prebuilt path matches path1, it issubstituted with path2.

Should be used if the perl library is moved from the defaultlocation in preference to PERL(5)LIB, since this would not leave wrongentries in @INC. For example, if the compiled version of perl looks for @INCin f:/perllib/lib, and you want to install the library inh:/opt/gnu, do

  1.   set PERLLIB_PREFIX=f:/perllib/lib;h:/opt/gnu
    2.

This will cause Perl with the prebuilt @INC of

  1.   f:/perllib/lib/5.00553/os2
    2.  
  2.   f:/perllib/lib/5.00553
    3.  
  3.   f:/perllib/lib/site_perl/5.00553/os2
    4.  
  4.   f:/perllib/lib/site_perl/5.00553
    5.  
  5.   .
    6.

to use the following @INC:

  1.   h:/opt/gnu/5.00553/os2
    2.  
  2.   h:/opt/gnu/5.00553
    3.  
  3.   h:/opt/gnu/site_perl/5.00553/os2
    4.  
  4.   h:/opt/gnu/site_perl/5.00553
    5.  
  5.   .
    6.

PERL_BADLANG

If 0, perl ignores setlocale() failing. May be useful with somestrange locales.

PERL_BADFREE

If 0, perl would not warn of in case of unwarranted free(). With olderperls this might beuseful in conjunction with the module DB_File, which was buggy whendynamically linked and OMF-built.

Should not be set with newer Perls, since this may hide some real problems.

PERL_SH_DIR

Specific for EMX port. Gives the directory part of the location forsh.exe.

USE_PERL_FLOCK

Specific for EMX port. Since flock(3) is present in EMX, but is not functional, it is emulated by perl. To disable the emulations, set environment variable USE_PERL_FLOCK=0.

TMP or TEMP

Specific for EMX port. Used as storage place for temporary files.

Evolution

Here we list major changes which could make you by surprise.

Text-mode filehandles

Starting from version 5.8, Perl uses a builtin translation layer fortext-mode files. This replaces the efficient well-tested EMX layer bysome code which should be best characterized as a "quick hack".

In addition to possible bugs and an inability to follow changes to thetranslation policy with off/on switches of TERMIO translation, thisintroduces a serious incompatible change: before sysread() ontext-mode filehandles would go through the translation layer, now itwould not.

Priorities

setpriority and getpriority are not compatible with earlierports by Andreas Kaiser. See "setpriority, getpriority".

DLL name mangling: pre 5.6.2

With the release 5.003_01 the dynamically loadable librariesshould be rebuilt when a different version of Perl is compiled. In particular,DLLs (including perl.dll) are now created with the nameswhich contain a checksum, thus allowing workaround for OS/2 scheme ofcaching DLLs.

It may be possible to code a simple workaround which would

  • find the old DLLs looking through the old @INC;

  • mangle the names according to the scheme of new perl and copy the DLLs tothese names;

  • edit the internal LX tables of DLL to reflect the change of the name(probably not needed for Perl extension DLLs, since the internally coded namesare not used for "specific" DLLs, they used only for "global" DLLs).

  • edit the internal IMPORT tables and change the name of the "old"perl????.dll to the "new" perl????.dll.

DLL name mangling: 5.6.2 and beyond

In fact mangling of extension DLLs was done due to misunderstandingof the OS/2 dynaloading model. OS/2 (effectively) maintains twodifferent tables of loaded DLL:

  • Global DLLs

    those loaded by the base name from LIBPATH; including thoseassociated at link time;

  • specific DLLs

    loaded by the full name.

When resolving a request for a global DLL, the table of already-loadedspecific DLLs is (effectively) ignored; moreover, specific DLLs arealways loaded from the prescribed path.

There is/was a minor twist which makes this scheme fragile: what to dowith DLLs loaded from

  • BEGINLIBPATH and ENDLIBPATH

    (which depend on the process)

  • . from LIBPATH

    which effectively depends on the process (although LIBPATH is thesame for all the processes).

Unless LIBPATHSTRICT is set to T (and the kernel is after2000/09/01), such DLLs are considered to be global. When loading aglobal DLL it is first looked in the table of already-loaded globalDLLs. Because of this the fact that one executable loaded a DLL fromBEGINLIBPATH and ENDLIBPATH, or . from LIBPATH may affectwhich DLL is loaded when another executable requests a DLL withthe same name. This is the reason for version-specific mangling ofthe DLL name for perl DLL.

Since the Perl extension DLLs are always loaded with the full path,there is no need to mangle their names in a version-specific ways:their directory already reflects the corresponding version of perl,and @INC takes into account binary compatibility with older version.Starting from 5.6.2 the name mangling scheme is fixed to be thesame as for Perl 5.005_53 (same as in a popular binary release). Thusnew Perls will be able to resolve the names of old extension DLLsif @INC allows finding their directories.

However, this still does not guarantee that these DLL may be loaded.The reason is the mangling of the name of the Perl DLL. And sincethe extension DLLs link with the Perl DLL, extension DLLs for olderversions would load an older Perl DLL, and would most probablysegfault (since the data in this DLL is not properly initialized).

There is a partial workaround (which can be made complete with newerOS/2 kernels): create a forwarder DLL with the same name as the DLL ofthe older version of Perl, which forwards the entry points to thenewer Perl's DLL. Make this DLL accessible on (say) the BEGINLIBPATH ofthe new Perl executable. When the new executable accesses old Perl'sextension DLLs, they would request the old Perl's DLL by name, get theforwarder instead, so effectively will link with the currently running(new) Perl DLL.

This may break in two ways:

  • Old perl executable is started when a new executable is running hasloaded an extension compiled for the old executable (ouph!). In thiscase the old executable will get a forwarder DLL instead of the oldperl DLL, so would link with the new perl DLL. While not directlyfatal, it will behave the same as new executable. This beats the wholepurpose of explicitly starting an old executable.

  • A new executable loads an extension compiled for the old executablewhen an old perl executable is running. In this case the extensionwill not pick up the forwarder - with fatal results.

With support for LIBPATHSTRICT this may be circumvented - unlessone of DLLs is started from . from LIBPATH (I do not knowwhether LIBPATHSTRICT affects this case).

REMARK. Unless newer kernels allow . in BEGINLIBPATH (olderdo not), this mess cannot be completely cleaned. (It turns out thatas of the beginning of 2002, . is not allowed, but .\. is - andit has the same effect.)

REMARK. LIBPATHSTRICT, BEGINLIBPATH and ENDLIBPATH arenot environment variables, although cmd.exe emulates them on SET... lines. From Perl they may be accessed byCwd::extLibpath andCwd::extLibpath_set.

DLL forwarder generation

Assume that the old DLL is named perlE0AC.dll (as is one for5.005_53), and the new version is 5.6.1. Create a fileperl5shim.def-leader with

  1.   LIBRARY 'perlE0AC' INITINSTANCE TERMINSTANCE
    2.  
  2.   DESCRIPTION '@#[email protected]:5.006001#@ Perl module for 5.00553 -> Perl 5.6.1 forwarder'
    3.  
  3.   CODE LOADONCALL
    4.  
  4.   DATA LOADONCALL NONSHARED MULTIPLE
    5.  
  5.   EXPORTS
    6.

modifying the versions/names as needed. Run

  1.  perl -wnle "next if 0../EXPORTS/; print qq(  \"$1\") if /\"(\w+)\"/" perl5.def >lst
    2.

in the Perl build directory (to make the DLL smaller replace perl5.defwith the definition file for the older version of Perl if present).

  1.  cat perl5shim.def-leader lst >perl5shim.def
    2.  
  2.  gcc -Zomf -Zdll -o perlE0AC.dll perl5shim.def -s -llibperl
    3.

(ignore multiple warning L4085).

Threading

As of release 5.003_01 perl is linked to multithreaded C RTLDLL. If perl itself is not compiled multithread-enabled, so will not be perl'smalloc(). However, extensions may use multiple thread on their ownrisk.

This was needed to compile Perl/Tk for XFree86-OS/2 out-of-the-box, andlink with DLLs for other useful libraries, which typically are compiledwith -Zmt -Zcrtdll.

Calls to external programs

Due to a popular demand the perl external program calling has beenchanged wrt Andreas Kaiser's port. If perl needs to call anexternal program via shell, the f:/bin/sh.exe will be called, orwhatever is the override, see PERL_SH_DIR.

Thus means that you need to get some copy of a sh.exe as well (Iuse one from pdksh). The path F:/bin above is set up automatically duringthe build to a correct value on the builder machine, but isoverridable at runtime,

Reasons: a consensus on perl5-porters was that perl should useone non-overridable shell per platform. The obvious choices for OS/2are cmd.exe and sh.exe. Having perl build itself would be impossiblewith cmd.exe as a shell, thus I picked up sh.exe. This assures almost100% compatibility with the scripts coming from *nix. As an added benefit this works as well under DOS if you use DOS-enabled port of pdksh (see Prerequisites).

Disadvantages: currently sh.exe of pdksh calls external programsvia fork()/exec(), and there is no functioning exec() onOS/2. exec() is emulated by EMX by an asynchronous call while the callerwaits for child completion (to pretend that the pid did not change). Thismeans that 1 extra copy of sh.exe is made active via fork()/exec(),which may lead to some resources taken from the system (even if we donot count extra work needed for fork()ing).

Note that this a lesser issue now when we do not spawn sh.exeunless needed (metachars found).

One can always start cmd.exe explicitly via

  1.   system 'cmd', '/c', 'mycmd', 'arg1', 'arg2', ...
    2.

If you need to use cmd.exe, and do not want to hand-edit thousands of yourscripts, the long-term solution proposed on p5-p is to have a directive

  1.   use OS2::Cmd;
    2.

which will override system(), exec(), ``, andopen(,'...|'). With current perl you may override only system(),readpipe() - the explicit version of ``, and maybe exec(). The codewill substitute the one-argument call to system() byCORE::system('cmd.exe', '/c', shift).

If you have some working code for OS2::Cmd, please send it to me,I will include it into distribution. I have no need for such a module, socannot test it.

For the details of the current situation with calling external programs,see 2 (and DOS) programs under Perl in Starting OS. Set us mention a coupleof features:

  • External scripts may be called by their basename. Perl will try the sameextensions as when processing -S command-line switch.

  • External scripts starting with #! or extproc will be executed directly,without calling the shell, by calling the program specified on the rest ofthe first line.

Memory allocation

Perl uses its own malloc() under OS/2 - interpreters are usually malloc-boundfor speed, but perl is not, since its malloc is lightning-fast.Perl-memory-usage-tuned benchmarks show that Perl's malloc is 5 times quickerthan EMX one. I do not have convincing data about memory footprint, buta (pretty random) benchmark showed that Perl's one is 5% better.

Combination of perl's malloc() and rigid DLL name resolution createsa special problem with library functions which expect their return value tobe free()d by system's free(). To facilitate extensions which need to call such functions, system memory-allocation functions are still available withthe prefix emx_ added. (Currently only DLL perl has this, it should propagate to perl_.exe shortly.)

Threads

One can build perl with thread support enabled by providing -D usethreadsoption to Configure. Currently OS/2 support of threads is very preliminary.

Most notable problems:

  • COND_WAIT

    may have a race condition (but probably does not due to edge-triggerednature of OS/2 Event semaphores). (Needs a reimplementation (in terms of chainingwaiting threads, with the linked list stored in per-thread structure?)?)

  • os2.c

    has a couple of static variables used in OS/2-specific functions. (Need to bemoved to per-thread structure, or serialized?)

Note that these problems should not discourage experimenting, since theyhave a low probability of affecting small programs.

BUGS

This description is not updated often (since 5.6.1?), see ./os2/Changesfor more info.

AUTHOR

Ilya Zakharevich, [email protected]

SEE ALSO

perl(1).

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