Index of Section 1 Manual Pages
| Interix / SUA | perlos2.1 | Interix / SUA |
PERLOS2(1) Perl Programmers Reference Guide PERLOS2(1)
NAME
perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and
WinNT.
SYNOPSIS
One can read this document in the following formats:
man perlos2
view perl perlos2
explorer perlos2.html
info perlos2
to list some (not all may be available simultaneously), or
it may be read as is: either as README.os2, or pod/per-
los2.pod.
To read the .INF version of documentation (very recom-
mended) outside of OS/2, one needs an IBM's reader (may be
available on IBM ftp sites (?) (URL anyone?)) or shipped
with PC DOS 7.0 and IBM's Visual Age C++ 3.5.
A copy of a Win* viewer is contained in the "Just add OS/2
Warp" package
ftp://ftp.software.ibm.com/ps/products/os2/tools/jaow/jaow.zip
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 links from this document in .INF for-
mat. If you have EMX docs installed correctly, you can
follow library links (you need to have "view emxbook"
working by setting "EMXBOOK" environment variable as it is
described in EMX docs).
DESCRIPTION
Target
The target is to make OS/2 one of the best supported plat-
form for using/building/developing Perl and Perl applica-
tions, as well as make Perl the best language to use under
OS/2. The secondary target is to 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:
o Some *nix programs use fork() a lot; with the mostly
useful flavors of perl for OS/2 (there are several
built simultaneously) this is supported; but some
flavors do not support this (e.g., when Perl is
called from inside REXX). Using fork() after useing
dynamically loading extensions would not work with
very old versions of EMX.
o You need a separate perl executable perl__.exe (see
perl__.exe) if you want to use PM code in your appli-
cation (as Perl/Tk or OpenGL Perl modules do) without
having a text-mode window present.
While using the standard perl.exe from a text-mode
window is possible too, I have seen cases when this
causes degradation of the system stability. Using
perl__.exe avoids such a degradation.
o There is no simple way to access WPS objects. The
only way I know is via "OS2::REXX" and "SOM" exten-
sions (see OS2::REXX, Som). However, we do not have
access to convenience methods of Object-REXX. (Is it
possible at all? I know of no Object-REXX API.) The
"SOM" extension (currently in alpha-text) may eventu-
ally remove this shortcoming; however, due to the
fact that DII is not supported by the "SOM" module,
using "SOM" is not as convenient 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 can run (and build extensions, and - possibly - be
built itself) under any environment 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
these environments. This depends on the features the
extender - most probably RSX - decided to implement.
Cf. Prerequisites.
Prerequisites
EMX EMX runtime is required (may be substituted by RSX).
Note that it is possible to make perl_.exe to run
under DOS without any external support by binding
emx.exe/rsx.exe to it, see emxbind. Note that under
DOS for best results one should use RSX runtime,
which has much more functions working (like "fork",
"popen" and so on). In fact RSX is required if there
is no VCPI present. Note the RSX requires DPMI.
Many implementations of DPMI are known to be very
buggy, beware!
Only the latest runtime is supported, currently
"0.9d fix 03". Perl may run under earlier versions
of EMX, but this is not tested.
One can get different parts of EMX from, say
http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/
http://powerusersbbs.com/pub/os2/dev/ [EMX+GCC Development]
http://hobbes.nmsu.edu/pub/os2/dev/emx/v0.9d/
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. One does not need to specify
them explicitly (though this
emx perl_.exe -de 0
will work as well.)
RSX To run Perl on DPMI platforms one needs RSX runtime.
This is needed under DOS-inside-OS/2, Win0.3*,
Win0.95 and WinNT (see "Other OSes"). RSX would not
work with VCPI only, 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", `` and pipe-"open" work. In fact, MakeMaker
works (for static build), so one can have Perl
development environment under DOS.
One can get RSX from, say
ftp://ftp.cdrom.com/pub/os2/emx09c/contrib
ftp://ftp.uni-bielefeld.de/pub/systems/msdos/misc
ftp://ftp.leo.org/pub/comp/os/os2/leo/devtools/emx+gcc/contrib
Contact the author on "rainer@mathematik.uni-biele-
feld.de".
The latest sh.exe with DOS hooks is available in
http://www.ilyaz.org/software/os2/
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 contains many files with long names, so to
install it intact one needs a file system which sup-
ports long file names.
Note that if you do not plan to build the perl
itself, it may be possible 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 with pipes in between, and/or quoting of
arguments), Perl uses an external shell. With EMX
port such shell should be named sh.exe, and located
either 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) runs under DOS (with RSX) as well,
see
http://www.ilyaz.org/software/os2/
Starting Perl programs under OS/2 (and DOS and...)
Start your Perl program foo.pl with arguments "arg1 arg2
arg3" the same way as on any other platform, by
perl foo.pl arg1 arg2 arg3
If you want to specify perl options "-my_opts" to the perl
itself (as opposed to your program), use
perl -my_opts foo.pl arg1 arg2 arg3
Alternately, if you use OS/2-ish shell, like CMD or 4os2,
put the following at the start of your perl script:
extproc perl -S -my_opts
rename your program to foo.cmd, and start it by typing
foo arg1 arg2 arg3
Note that because of stupid OS/2 limitations the full path
of the perl script is not available when you use
"extproc", thus you are forced to use "-S" perl switch,
and your script should be on the "PATH". As a plus side,
if you know a full path to your script, you may still
start it with
perl ../../blah/foo.cmd arg1 arg2 arg3
(note that the argument "-my_opts" is taken care of by the
"extproc" line in your script, see ""extproc" on the first
line").
To understand what the above magic does, read perl docs
about "-S" switch - see perlrun, and cmdref about
"extproc":
view perl perlrun
man perlrun
view cmdref extproc
help extproc
or whatever method you prefer.
There are also endless possibilities to use executable
extensions of 4os2, associations of WPS and so on... How-
ever, if you use *nixish shell (like sh.exe supplied in
the binary distribution), you need to follow the syntax
specified in "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" in perlfunc), `` (see
"I/O Operators" in perlop), and open pipe (see "open" in
perlfunc) are for. (Avoid exec() (see "exec" in perlfunc)
unless you know what you do).
Note however that to use some of these operators you need
to have a sh-syntax shell installed (see "Pdksh", "Fre-
quently 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" in perlfunc),
exec() (see "exec" in perlfunc) with redirection or
shell meta-characters;
2 Pipe-open (see "open" in perlfunc) with the command
which contains redirection or shell meta-characters;
3 Backticks `` (see "I/O Operators" in perlop) with the
command which contains redirection or shell
meta-characters;
4 If the executable called by sys-
tem()/exec()/pipe-open()/`` is a script with the
"magic" "#!" line or "extproc" line which specifies
shell;
5 If the executable called by sys-
tem()/exec()/pipe-open()/`` is a script without
"magic" line, and $ENV{EXECSHELL} is set to shell;
6 If the executable called by sys-
tem()/exec()/pipe-open()/`` is not found (is not this
remark obsolete?);
7 For globbing (see "glob" in perlfunc, "I/O Operators"
in perlop) (obsolete? Perl uses builtin globbing nowa-
days...).
For the sake of speed for a common case, in the above
algorithms backslashes in the command name are not consid-
ered as shell metacharacters.
Perl starts scripts which begin with cookies "extproc" or
"#!" directly, without an intervention of shell. Perl
uses the same algorithm to find the executable as pdksh:
if the path on "#!" line does not work, and contains "/",
then the directory part of the executable is ignored, and
the executable is searched in . and on "PATH". To find
arguments for these scripts Perl uses a different algo-
rithm than pdksh: up to 3 arguments are recognized, and
trailing whitespace is stripped.
If a script does not contain such a cooky, then to avoid
calling sh.exe, Perl uses the same algorithm as pdksh: if
$ENV{EXECSHELL} is set, the script is given as the first
argument to this command, if not set, then "$ENV{COMSPEC}
/c" is used (or a hardwired guess if $ENV{COMSPEC} is not
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 in the 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 the specified application, thus "system
'blah'" will not look for a script if there is an exe-
cutable file blah.exe anywhere on "PATH". In other words,
"PATH" is essentially searched twice: once by the OS for
an executable, then by Perl for scripts.
Note also that executable files on OS/2 can have an arbi-
trary 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 exe-
cutable 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 a separate PM session; the opposite is not
true: when you start a non-PM program from a PM Perl pro-
cess, Perl would not run it in a separate session. If a
separate session is desired, either ensure that shell will
be used, as in "system 'cmd /c myprog'", or start it using
optional arguments to system() documented in "OS2::Pro-
cess" module. This is considered to be a feature.
Frequently asked questions
"It does not work"
Perl binary distributions come with a testperl.cmd script
which tries to detect common problems with misconfigured
installations. There is a pretty large chance it will
discover which step of the installation you managed to
goof. ";-)"
I cannot run external programs
o Did you run your programs with "-w" switch? See "2
(and DOS) programs under Perl" in Starting OS.
o Do you try to run internal shell commands, like `copy
a b` (internal for cmd.exe), or `glob a*b` (internal
for ksh)? You need 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
my program.
Is your program EMX-compiled with "-Zmt -Zcrtdll"?
Well, nowadays Perl DLL should be usable from a dif-
ferently compiled program too... If you can run Perl
code from REXX scripts (see OS2::REXX), then there are
some other aspect of interaction which are overlooked
by the current hackish code to support differently-
compiled principal programs.
If everything else fails, you need to build a stand-
alone DLL for perl. Contact me, I did it once. Sockets
would not work, as a lot of other stuff.
Did you use ExtUtils::Embed?
Some time ago I had reports it does not work. Nowa-
days it is checked in the Perl test suite, so grep ./t
subdirectory of the build tree (as well as *.t files
in the ./lib subdirectory) to find how it should be
done "correctly".
`` and pipe-"open" do not work under DOS.
This may a variant of just "I cannot run external pro-
grams", or a deeper problem. Basically: you need RSX (see
"Prerequisites") for these commands to work, and you may
need a port of sh.exe which understands command arguments.
One of such ports is listed in "Prerequisites" under RSX.
Do not forget to set variable ""PERL_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 applica-
tions" is that the forms "foo" and "foo" of program argu-
ments are completely interchangable. find breaks this
paradigm;
find "pattern" file
find pattern file
are not equivalent; find cannot be started directly using
the above API. One needs a way to surround the double-
quotes in some other quoting construction, necessarily
having an extra non-Unixish shell in between.
Use one of
system 'cmd', '/c', 'find "pattern" file';
`cmd /c 'find "pattern" file'`
This would start find.exe via cmd.exe via "sh.exe" via
"perl.exe", but this is a price to pay if you want to use
non-conforming program.
INSTALLATION
Automatic binary installation
The most convenient way of installing a binary distribu-
tion of perl is via perl installer install.exe. Just fol-
low the instructions, and 99% of the installation blues
would go away.
Note however, that you need to have unzip.exe on your
path, and EMX environment running. The latter means that
if you just installed EMX, and made all the needed changes
to Config.sys, you may need to reboot in between. Check
EMX runtime by running
emxrev
Binary installer also creates a folder on your desktop
with some useful objects. If you need to change some
aspects of the work of the binary installer, feel free to
edit the file Perl.pkg. This may be useful e.g., if you
need to run the installer many times and do not want to
make 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_BAD-
LANG".
"PERL_BADFREE" see "PERL_BADFREE".
Config.pm This file resides somewhere deep in the
location you installed your perl library,
find it out by
perl -MConfig -le "print $INC{'Config.pm'}"
While most important values in this file
are updated by the binary installer, some
of them may need to be hand-edited. I know
no such data, please keep me informed if
you find one. Moreover, manual changes to
the installed version may need to be accom-
panied by an edit of this file.
NOTE. Because of a typo the binary installer of 5.00305
would install a variable "PERL_SHPATH" into Config.sys.
Please remove this variable and put "PERL_SH_DIR" instead.
Manual binary installation
As of version 5.00305, OS/2 perl binary distribution comes
split into 11 components. Unfortunately, to enable config-
urable binary installation, the file paths in the zip
files are not absolute, but relative to some directory.
Note that the extraction with the stored paths is still
necessary (default with unzip, specify "-d" to pkunzip).
However, you need to know where to extract the files. You
need also to manually change entries in Config.sys to
reflect where did you put the files. Note that if you have
some primitive unzipper (like "pkunzip"), you may get a
lot of warnings/errors during unzipping. Upgrade to
"(w)unzip".
Below is the sample of what to do to reproduce the config-
uration on my machine. In VIEW.EXE you can press
"Ctrl-Insert" now, and cut-and-paste from the resulting
file - created in the directory you started VIEW.EXE from.
For each component, we mention environment variables
related to each installation directory. Either choose
directories to match your values of the variables, or cre-
ate/append-to variables to take into account the directo-
ries.
Perl VIO and PM executables (dynamically linked)
unzip perl_exc.zip *.exe *.ico -d f:/emx.add/bin
unzip perl_exc.zip *.dll -d f:/emx.add/dll
(have the directories with "*.exe" on PATH, and "*.dll"
on LIBPATH);
Perl_ VIO executable (statically linked)
unzip perl_aou.zip -d f:/emx.add/bin
(have the directory on PATH);
Executables for Perl utilities
unzip perl_utl.zip -d f:/emx.add/bin
(have the directory on PATH);
Main Perl library
unzip perl_mlb.zip -d f:/perllib/lib
If this directory is exactly the same as the prefix
which was compiled into perl.exe, you do not need to
change anything. However, for perl to find the library
if you use a different path, you need to "set PERL-
LIB_PREFIX" in Config.sys, see "PERLLIB_PREFIX".
Additional Perl modules
unzip perl_ste.zip -d f:/perllib/lib/site_perl/5.8.8/
Same remark as above applies. Additionally, if this
directory is not one of directories on @INC (and @INC
is influenced by "PERLLIB_PREFIX"), you need to put
this directory and subdirectory ./os2 in "PERLLIB" or
"PERL5LIB" variable. Do not use "PERL5LIB" unless you
have it set already. See "ENVIRONMENT" in perl.
[Check whether this extraction directory is still
applicable with the new directory structure layout!]
Tools to compile Perl modules
unzip perl_blb.zip -d f:/perllib/lib
Same remark as for perl_ste.zip.
Manpages for Perl and utilities
unzip perl_man.zip -d f:/perllib/man
This directory should better be on "MANPATH". You need
to have a working man to access these files.
Manpages for Perl modules
unzip perl_mam.zip -d f:/perllib/man
This directory should better be on "MANPATH". You need
to have a working man to access these files.
Source for Perl documentation
unzip perl_pod.zip -d f:/perllib/lib
This is used by the "perldoc" program (see perldoc),
and may be used to generate HTML documentation usable
by WWW browsers, and documentation in zillions of other
formats: "info", "LaTeX", "Acrobat", "FrameMaker" and
so on. [Use programs such as pod2latex etc.]
Perl manual in .INF format
unzip perl_inf.zip -d d:/os2/book
This directory should better be on "BOOKSHELF".
Pdksh
unzip perl_sh.zip -d f:/bin
This is used by perl to run external commands which
explicitly require shell, like the commands using redi-
rection and shell metacharacters. It is also used
instead of explicit /bin/sh.
Set "PERL_SH_DIR" (see "PERL_SH_DIR") if you move
sh.exe from the above location.
Note. It may be possible to use some other sh-compati-
ble shell (untested).
After you installed the components you needed and updated
the Config.sys correspondingly, you need to hand-edit Con-
fig.pm. This file resides somewhere deep in the location
you installed your perl library, find it out by
perl -MConfig -le "print $INC{'Config.pm'}"
You need to correct all the entries which look like file
paths (they currently start with "f:/").
Warning
The automatic and manual perl installation leave precom-
piled paths inside perl executables. While these paths are
overwriteable (see "PERLLIB_PREFIX", "PERL_SH_DIR"), some
people may prefer binary editing of paths inside the exe-
cutables/DLLs.
Accessing documentation
Depending on how you built/installed perl you may have
(otherwise identical) Perl documentation in the following
formats:
OS/2 .INF file
Most probably the most convenient form. Under OS/2 view it
as
view perl
view perl perlfunc
view perl less
view perl ExtUtils::MakeMaker
(currently the last two may hit a wrong location, but this
may improve soon). Under Win* see "SYNOPSIS".
If you want to build the docs yourself, and have OS/2
toolkit, run
pod2ipf > perl.ipf
in /perllib/lib/pod directory, then
ipfc /inf perl.ipf
(Expect a lot of errors during the both steps.) Now move
it on your BOOKSHELF path.
Plain text
If you have perl documentation in the source form, perl
utilities installed, and GNU groff installed, you may use
perldoc perlfunc
perldoc less
perldoc ExtUtils::MakeMaker
to access the perl documentation in the text form (note
that you may get better results using perl manpages).
Alternately, try running pod2text on .pod files.
Manpages
If you have man installed on your system, and you
installed perl manpages, use something like this:
man perlfunc
man 3 less
man ExtUtils.MakeMaker
to access documentation for different components of Perl.
Start with
man perl
Note that dot (.) is used as a package separator for docu-
mentation for packages, and as usual, sometimes you need
to give the section - 3 above - to avoid shadowing by the
less(1) manpage.
Make sure that the directory above the directory with man-
pages is on our "MANPATH", like this
set MANPATH=c:/man;f:/perllib/man
for Perl manpages in "f:/perllib/man/man1/" etc.
HTML
If you have some WWW browser available, installed the Perl
documentation in the source form, and Perl utilities, you
can build HTML docs. Cd to directory with .pod files, and
do like this
cd f:/perllib/lib/pod
pod2html
After this you can direct your browser the file perl.html
in this directory, and go ahead with reading docs, like
this:
explore file:///f:/perllib/lib/pod/perl.html
Alternatively you may be able to get these docs prebuilt
from CPAN.
GNU "info" files
Users of Emacs would appreciate it very much, especially
with "CPerl" 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 of perl).
"LaTeX" docs
can be constructed using "pod2latex".
BUILD
Here we discuss how to build Perl under OS/2. There is an
alternative (but maybe older) view on
.
The short story
Assume that you are a seasoned porter, so are sure that
all the necessary tools are already present on your sys-
tem, and you know how to get the Perl source distribution.
Untar it, change to the extract directory, and
gnupatch -p0 < os2\diff.configure
sh Configure -des -D prefix=f:/perllib
make
make test
make install
make aout_test
make aout_install
This puts the executables in f:/perllib/bin. Manually
move them to the "PATH", manually move the built perl*.dll
to "LIBPATH" (here for Perl DLL * is a not-very-meaningful
hex checksum), and run
make installcmd INSTALLCMDDIR=d:/ir/on/path
Assuming that the "man"-files were put on an appropriate
location, this completes the installation of minimal Perl
system. (The binary distribution contains also a lot of
additional modules, and the documentation in INF format.)
What follows is a detailed guide through these steps.
Prerequisites
You need to have the latest EMX development environment,
the full GNU tool suite (gawk renamed to awk, and GNU
find.exe earlier on path than the OS/2 find.exe, same with
sort.exe, to check use
find --version
sort --version
). 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:
ftp://hobbes.nmsu.edu/os2/unix/
ftp://ftp.cdrom.com/pub/os2/unix/
ftp://ftp.cdrom.com/pub/os2/dev32/
ftp://ftp.cdrom.com/pub/os2/emx09c/
It is reported that the following archives contain enough
utils to build perl: gnufutil.zip, gnusutil.zip, gnutu-
til.zip, gnused.zip, gnupatch.zip, gnuawk.zip, gnu-
make.zip, gnugrep.zip, bsddev.zip and ksh527rt.zip (or a
later version). Note that all these utilities are known
to be available from LEO:
ftp://ftp.leo.org/pub/comp/os/os2/leo/gnu
Note also that the db.lib and db.a from the EMX distribu-
tion are not suitable for multi-threaded compile (even
single-threaded flavor of Perl uses multi-threaded C RTL,
for compatibility with XFree86-OS/2). Get a corrected one
from
http://www.ilyaz.org/software/os2/db_mt.zip
If you have exactly the same version of Perl installed
already, make sure that no copies or perl are currently
running. Later steps of the build may fail since an older
version of perl.dll loaded into memory may be found. Run-
ning "make test" becomes meaningless, since the test are
checking a previous build of perl (this situation is
detected and reported by lib/os2_base.t test). Do not
forget to unset "PERL_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 the latter condition by
set BEGINLIBPATH .\.
if you use something like CMD.EXE or latest versions of
4os2.exe. (Setting BEGINLIBPATH to just "." is ignored by
the OS/2 kernel.)
Make sure your gcc is good for "-Zomf" linking: run
"omflibs" script 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
link386
shows you do not have it, do Selective install, and choose
"Link object modules" in Optional system utilities/More.
If you get into link386 prompts, press "Ctrl-C" to exit.
Getting perl source
You need to fetch the latest perl source (including devel-
opers releases). With some probability it is located in
http://www.cpan.org/src/5.0
http://www.cpan.org/src/5.0/unsupported
If not, you may need to dig in the indices to find it in
the directory of the current maintainer.
Quick cycle of developers release may break the OS/2 build
time to time, looking into
http://www.cpan.org/ports/os2/
may indicate the latest release which was publicly
released by the maintainer. Note that the release may
include some additional patches to apply to the current
source of perl.
Extract it like this
tar vzxf perl5.00409.tar.gz
You may see a message about errors while extracting Con-
figure. This is because there is a conflict with a simi-
larly-named file configure.
Change to the directory of extraction.
Application of the patches
You need to apply the patches in ./os2/diff.* like this:
gnupatch -p0 < os2\diff.configure
You may also need to apply the patches supplied with the
binary distribution of perl. It also makes sense to look
on the perl5-porters mailing list for the latest
OS/2-related patches (see
). Such patches usually contain
strings "/os2/" and "patch", so it makes sense looking for
these strings.
Hand-editing
You may look into the file ./hints/os2.sh and correct any-
thing wrong you find there. I do not expect it is needed
anywhere.
Making
sh Configure -des -D prefix=f:/perllib
"prefix" means: where to install the resulting perl
library. Giving correct prefix you may avoid the need to
specify "PERLLIB_PREFIX", see "PERLLIB_PREFIX".
Ignore the message about missing "ln", and about "-c"
option to tr. The latter is most probably already fixed,
if you see it and can trace where the latter spurious
warning comes from, please inform me.
Now
make
At some moment the built may die, reporting a version mis-
match or unable to run perl. This means that you do not
have . in your LIBPATH, so perl.exe cannot find the needed
perl67B2.dll (treat these hex digits as line noise).
After this is fixed the build should finish without a lot
of fuss.
Testing
Now run
make test
All tests should succeed (with some of them skipped). If
you have the same version of Perl installed, it is crucial
that you have "." early in your LIBPATH (or in BEGINLIB-
PATH), otherwise your tests will most probably 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 applica-
tions. *nix applications die in silence. It is consid-
ered to be a feature. One can easily disable this by
appropriate sighandlers.
However the test engine bleeds these message to screen
in unexpected moments. Two messages of this kind
should be present during testing.
To get finer test reports, call
perl t/harness
The report with io/pipe.t failing may look like this:
Failed Test Status Wstat Total Fail Failed List of failed
------------------------------------------------------------
io/pipe.t 12 1 8.33% 9
7 tests skipped, plus 56 subtests skipped.
Failed 1/195 test scripts, 99.49% okay. 1/6542 subtests failed, 99.98% okay.
The reasons for most important skipped tests are:
op/fs.t
18 Checks "atime" and "mtime" of "stat()" -
unfortunately, HPFS provides only 2sec time
granularity (for compatibility with FAT?).
25 Checks "truncate()" on a filehandle just
opened for write - I do not know why this
should or should not work.
op/stat.t
Checks "stat()". Tests:
4 Checks "atime" and "mtime" of "stat()" -
unfortunately, HPFS provides 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
make install
It would put the generated files into needed locations.
Manually put perl.exe, perl__.exe and perl___.exe to a
location on your PATH, perl.dll to a location on your LIB-
PATH.
Run
make installcmd INSTALLCMDDIR=d:/ir/on/path
to convert perl utilities to .cmd files and put them on
PATH. You need to put .EXE-utilities on path manually.
They are installed in "$prefix/bin", here $prefix is what
you gave to Configure, see Making.
If you use "man", either move the installed */man/ direc-
tories to your "MANPATH", or modify "MANPATH" to match the
location. (One could have avoided this by providing a
correct "manpath" option to ./Configure, or editing ./con-
fig.sh between configuring and making steps.)
"a.out"-style build
Proceed as above, but make perl_.exe (see "perl_.exe") by
make perl_
test and install by
make aout_test
make aout_install
Manually put perl_.exe to a location on your PATH.
Note. The build process for "perl_" does not know about
all the dependencies, so you should make sure that any-
thing is up-to-date, say, by doing
make perl_dll
first.
Building a binary distribution
[This section provides a short overview only...]
Building should proceed differently depending on whether
the version of perl you install is already present and
used on your system, or is a new version not yet used.
The description below assumes that the version is new, so
installing its DLLs and .pm files will not disrupt the
operation of your system even if some intermediate steps
are not yet fully working.
The other cases require a little bit more convoluted pro-
cedures. Below I suppose that the current version of Perl
is 5.8.2, so the executables are named accordingly.
1. Fully build and test the Perl distribution. Make sure
that no tests are failing with "test" and "aout_test"
targets; fix the bugs in Perl and the Perl test suite
detected by these tests. Make sure that "all_test"
make target runs as clean as possible. Check that
"os2/perlrexx.cmd" runs fine.
2. Fully install Perl, including "installcmd" target.
Copy the generated DLLs to "LIBPATH"; copy the num-
bered Perl executables (as in perl5.8.2.exe) to
"PATH"; copy "perl_.exe" to "PATH" as
"perl_5.8.2.exe". Think whether you need backward-
compatibility DLLs. In most cases you do not need to
install them yet; but sometime this may simplify the
following steps.
3. Make sure that "CPAN.pm" can download files from CPAN.
If not, you may need to manually install "Net::FTP".
4. Install the bundle "Bundle::OS2_default"
perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_1
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 not
specify required dependencies, so one may need to
repeat this procedure several times until the results
stabilize.
perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_2
perl5.8.2 -MCPAN -e "install Bundle::OS2_default" < nul |& tee 00cpan_i_3
Even after they stabilize, some tests may fail.
Fix as many discovered bugs as possible. Document all
the bugs which are not fixed, and all the failures
with unknown reasons. Inspect the produced logs
00cpan_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 "install" logs
(in the example above 00cpan_i_1 etc) for errors, and
install things manually, as in
cd $CPANHOME/.cpan/build/Digest-MD5-2.31
make install
Some distributions may fail some tests, but you may
want to install them anyway (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 sense to "freeze" your CPAN config-
uration by disabling periodic updates of the local
copy of CPAN index: set "index_expire" to some big
value (I use 365), then save the settings
CPAN> o conf index_expire 365
CPAN> o conf commit
Reset back to the default value 1 when you are fin-
ished.
5. When satisfied with the results, rerun the "install-
cmd" target. Now you can copy "perl5.8.2.exe" to
"perl.exe", and install the other OMF-build executa-
bles: "perl__.exe" etc. They are ready to be used.
6. Change to the "./pod" directory of the build tree,
download the Perl logo CamelGrayBig.BMP, and run
( perl2ipf > perl.ipf ) |& tee 00ipf
ipfc /INF perl.ipf |& tee 00inf
This produces the Perl docs online book "perl.INF".
Install in on "BOOKSHELF" path.
7. Now is the time to build statically linked executable
perl_.exe which includes newly-installed via "Bun-
dle::OS2_default" modules. Doing testing via
"CPAN.pm" is going to be painfully slow, since it
statically links a new executable per XS extension.
Here is a possible workaround: create a toplevel Make-
file.PL in $CPANHOME/.cpan/build/ with contents being
(compare with "Making executables with a custom col-
lection of statically loaded extensions")
use ExtUtils::MakeMaker;
WriteMakefile NAME => 'dummy';
execute this as
perl_5.8.2.exe Makefile.PL :
use ExtUtils::MakeMaker;
WriteMakefile NAME => 'dummy';
2. Run it with the flavor of Perl (perl.exe or perl_.exe)
you want to rebuild.
perl_ Makefile.PL
3. Ask it to create new Perl executable:
make perl
(you may need to manually add "PERLTYPE=-DPERL_CORE"
to this commandline on some versions of Perl; the
symptom is that the command-line globbing does not
work from OS/2 shells with the newly-compiled exe-
cutable; check with
.\perl.exe -wle "print for @ARGV" *
).
4. The previous step created perlmain.c which contains a
list of newXS() calls near the end. Removing unneces-
sary calls, and rerunning
make perl
will produce a customized executable.
Making executables with a custom search-paths
The default perl executable is flexible enough to support
most usages. However, one may want something yet more
flexible; for example, one may want to find Perl DLL rela-
tively to the location of the EXE file; or one may want to
ignore the environment when setting the Perl-library
search patch, etc.
If you fill comfortable with embedding interface (see per-
lembed), such things are easy to do repeating the steps
outlined in "Making executables with a custom collection
of statically loaded extensions", and doing more compre-
hensive edits to main() of perlmain.c. The people with
little desire to understand Perl can just rename main(),
and do necessary modification in a custom main() which
calls the renamed function in appropriate time.
However, there is a third way: perl DLL exports the main()
function and several callbacks to customize the search
path. Below is a complete example of a "Perl loader"
which
1. Looks for Perl DLL in the directory "$exedir/../dll";
2. Prepends the above directory to "BEGINLIBPATH";
3. Fails if the Perl DLL found via "BEGINLIBPATH" is dif-
ferent from what was loaded on step 1; e.g., another
process could have loaded it from "LIBPATH" or from a
different value of "BEGINLIBPATH". In these cases one
needs to modify the setting of the system so that this
other process either does not run, or loads the DLL
from "BEGINLIBPATH" with "LIBPATHSTRICT=T" (available
with 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 Perl DLL. However, a lot of functionality
will work even if the executable is not an EMX applica-
tions, e.g., if compiled with
gcc -Wall -DDOSISH -DOS2=1 -O2 -s -Zomf -Zsys perl-starter.c -DPERL_DLL_BASENAME=\"perl312F\" -Zstack 8192 -Zlinker /PM:VIO
Here is the sample C file:
#define INCL_DOS
#define INCL_NOPM
/* These are needed for compile if os2.h includes os2tk.h, not os2emx.h */
#define INCL_DOSPROCESS
#include
#include "EXTERN.h"
#define PERL_IN_MINIPERLMAIN_C
#include "perl.h"
static char *me;
HMODULE handle;
static void
die_with(char *msg1, char *msg2, char *msg3, char *msg4)
{
ULONG c;
char *s = " error: ";
DosWrite(2, me, strlen(me), &c);
DosWrite(2, s, strlen(s), &c);
DosWrite(2, msg1, strlen(msg1), &c);
DosWrite(2, msg2, strlen(msg2), &c);
DosWrite(2, msg3, strlen(msg3), &c);
DosWrite(2, msg4, strlen(msg4), &c);
DosWrite(2, "\r\n", 2, &c);
exit(255);
}
typedef ULONG (*fill_extLibpath_t)(int type, char *pre, char *post, int replace, char *msg);
typedef int (*main_t)(int type, char *argv[], char *env[]);
typedef int (*handler_t)(void* data, int which);
#ifndef PERL_DLL_BASENAME
# define PERL_DLL_BASENAME "perl"
#endif
static HMODULE
load_perl_dll(char *basename)
{
char buf[300], fail[260];
STRLEN l, dirl;
fill_extLibpath_t f;
ULONG rc_fullname;
HMODULE handle, handle1;
if (_execname(buf, sizeof(buf) - 13) != 0)
die_with("Can't find full path: ", strerror(errno), "", "");
/* XXXX Fill `me' with new value */
l = strlen(buf);
while (l && buf[l-1] != '/' && buf[l-1] != '\\')
l--;
dirl = l - 1;
strcpy(buf + l, basename);
l += strlen(basename);
strcpy(buf + l, ".dll");
if ( (rc_fullname = DosLoadModule(fail, sizeof fail, buf, &handle)) != 0
&& DosLoadModule(fail, sizeof fail, basename, &handle) != 0 )
die_with("Can't load DLL ", buf, "", "");
if (rc_fullname)
return handle; /* was loaded with short name; all is fine */
if (DosQueryProcAddr(handle, 0, "fill_extLibpath", (PFN*)&f))
die_with(buf, ": DLL exports no symbol ", "fill_extLibpath", "");
buf[dirl] = 0;
if (f(0 /*BEGINLIBPATH*/, buf /* prepend */, NULL /* append */,
0 /* keep old value */, me))
die_with(me, ": prepending BEGINLIBPATH", "", "");
if (DosLoadModule(fail, sizeof fail, basename, &handle1) != 0)
die_with(me, ": finding perl DLL again via BEGINLIBPATH", "", "");
buf[dirl] = '\\';
if (handle1 != handle) {
if (DosQueryModuleName(handle1, sizeof(fail), fail))
strcpy(fail, "???");
die_with(buf, ":\n\tperl DLL via BEGINLIBPATH is different: \n\t",
fail,
"\n\tYou may need to manipulate global BEGINLIBPATH and LIBPATHSTRICT"
"\n\tso that the other copy is loaded via BEGINLIBPATH.");
}
return handle;
}
int
main(int argc, char **argv, char **env)
{
main_t f;
handler_t h;
me = argv[0];
/**/
handle = load_perl_dll(PERL_DLL_BASENAME);
if (DosQueryProcAddr(handle, 0, "Perl_OS2_handler_install", (PFN*)&h))
die_with(PERL_DLL_BASENAME, ": DLL exports no symbol ", "Perl_OS2_handler_install", "");
if ( !h((void *)"~installprefix", Perlos2_handler_perllib_from)
|| !h((void *)"~dll", Perlos2_handler_perllib_to)
|| !h((void *)"~dll/sh/ksh.exe", Perlos2_handler_perl_sh) )
die_with(PERL_DLL_BASENAME, ": Can't install @INC manglers", "", "");
if (DosQueryProcAddr(handle, 0, "dll_perlmain", (PFN*)&f))
die_with(PERL_DLL_BASENAME, ": DLL exports no symbol ", "dll_perlmain", "");
return f(argc, argv, env);
}
Build FAQ
Some "/" became "\" in pdksh.
You have a very old pdksh. See Prerequisites.
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,
which broke 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 older ports of '94 - 95. The priorities are abso-
lute, go from 32 to -95, lower is quicker. 0 is the
default priority.
WARNING. Calling "getpriority" on a non-existing process
could lock the system before Warp3 fixpak22. Starting
with Warp3, Perl will use a workaround: it aborts getpri-
ority() if the process is not present. This is not possi-
ble on older versions "2.*", and has a race condition any-
way.
"system()"
Multi-argument form of "system()" allows an additional
numeric argument. The meaning of this argument is
described in OS2::Process.
When finding a program to run, Perl first asks the OS to
look for executables on "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 magic strings "#!" and "extproc
". If found, Perl uses the rest of the first line as the
beginning of the command line to run this script. The
only mangling done to the first line is extraction of
arguments (currently up to 3), and ignoring of the path-
part of the "interpreter" name if it can't be found using
the full path.
E.g., "system 'foo', 'bar', 'baz'" may lead Perl to find-
ing C:/emx/bin/foo.cmd with the first line being
extproc /bin/bash -x -c
If /bin/bash.exe is not found, then Perl looks for an exe-
cutable bash.exe on "PATH". If found in
C:/emx.add/bin/bash.exe, then the above system() is trans-
lated to
system qw(C:/emx.add/bin/bash.exe -x -c C:/emx/bin/foo.cmd bar baz)
One additional translation is performed: instead of
/bin/sh Perl uses the hardwired-or-customized shell (see
""PERL_SH_DIR"").
The above search for "interpreter" is recursive: if bash
executable is not found, 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 limit 4 on
the number of additional arguments inserted before the
actual arguments given to system(). In particular, if no
additional arguments are specified on the "magic" first
lines, then the limit on the depth is 4.
If Perl finds that the found executable is of PM type when
the current session is not, it will start the new process
in a separate session of necessary type. Call via
"OS2::Process" to disable this magic.
WARNING. Due to the described logic, you need to explic-
itly specify .com extension if needed. Moreover, if the
executable perl5.6.1 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 treated as "#!"-line, thus all the switches on
this line are processed (twice if script was started via
cmd.exe). See "DESCRIPTION" in perlrun.
Additional modules:
OS2::Process, OS2::DLL, OS2::REXX, OS2::PrfDB,
OS2::ExtAttr. These modules provide access to additional
numeric argument for "system" and to the information about
the running process, to DLLs having functions with REXX
signature and to the REXX runtime, to OS/2 databases in
the .INI format, and to Extended Attributes.
Two additional extensions by Andreas Kaiser, "OS2::UPM",
and "OS2::FTP", are included into "ILYAZ" directory, mir-
rored on CPAN. Other OS/2-related extensions are avail-
able 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)"
chanes 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-let-
ter:).
"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 of file which would have "name" if CWD
were "dir". "Dir" defaults to the current dir.
"Cwd::extLibpath([type])"
Get current value of extended library search path. If
"type" is present and positive, works with "END_LIB-
PATH", if negative, works with "LIBPATHSTRICT", other-
wise with "BEGIN_LIBPATH".
"Cwd::extLibpath_set( path [, type ] )"
Set current value of extended library search path. If
"type" is present and positive, works with , if negative, works with "LIBPATHSTRICT", other-
wise with "BEGIN_LIBPATH".
"OS2::Error(do_harderror,do_exception)"
Returns "undef" if it was not called yet, otherwise
bit 1 is set if on the previous call do_harderror was
enabled, bit 2 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 soft-
ware exceptions.
I know of no way to find out the state of popups
before the first call to this function.
"OS2::Errors2Drive(drive)"
Returns "undef" if it was not called yet, otherwise
return false if errors were not requested to be writ-
ten to a hard drive, or the drive letter if this was
requested.
This function may redirect error popups associated
with hardware errors (Disk not ready etc.) and soft-
ware exceptions to the file POPUPLOG.OS2 at the root
directory of the specified drive. Overrides
OS2::Error() specified by 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 disk before the first call to this
function.
OS2::SysInfo()
Returns a hash with system information. The keys of
the hash are
MAX_PATH_LENGTH, MAX_TEXT_SESSIONS, MAX_PM_SESSIONS,
MAX_VDM_SESSIONS, BOOT_DRIVE, DYN_PRI_VARIATION,
MAX_WAIT, MIN_SLICE, MAX_SLICE, PAGE_SIZE,
VERSION_MAJOR, VERSION_MINOR, VERSION_REVISION,
MS_COUNT, TIME_LOW, TIME_HIGH, TOTPHYSMEM, TOTRESMEM,
TOTAVAILMEM, MAXPRMEM, MAXSHMEM, TIMER_INTERVAL,
MAX_COMP_LENGTH, FOREGROUND_FS_SESSION,
FOREGROUND_PROCESS
OS2::BootDrive()
Returns a letter without colon.
"OS2::MorphPM(serve)", "OS2::UnMorphPM(serve)"
Transforms the current application into a PM applica-
tion 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 addi-
tional 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 to be 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 cre-
ation/destruction. If "force" is false, will not dis-
patch messages if a real message loop is 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, returns the previous coprocessor control
word as an integer. Only bits in "new" which are pre-
sent 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 for handling exception mask: if no "mask", uses
exception mask part of "new" only. If no "new", dis-
ables 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 C function bound to by &xsub. The
meaning of "how" is: default (2): full name; 0: han-
dle; 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 same as _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 exe-
cutable, so Perl can fork. Do not use this, use the
portable check for $Config::Config{dfork}.
$OS2::nsyserror
This variable (default is 1) controls whether to
enforce the contents of $^E to start with
"SYS0003"-like id. If set to 0, then the string value
of $^E is what is available from the OS/2 message
file. (Some messages in this file have an
"SYS0003"-like id prepended, some not.)
Misfeatures
o Since flock(3) is present in EMX, but is not func-
tional, it is emulated by perl. To disable the emula-
tions, set environment variable "USE_PERL_FLOCK=0".
o Here is the list of things which may be "broken" on
EMX (from EMX docs):
o The functions recvmsg(3), sendmsg(3), and socket-
pair(3) are not implemented.
o sock_init(3) is not required and not implemented.
o flock(3) is not yet implemented (dummy function).
(Perl has a workaround.)
o kill(3): Special treatment of PID=0, PID=1 and
PID=-1 is not implemented.
o waitpid(3):
WUNTRACED
Not implemented.
waitpid() is not implemented for negative values of PID.
Note that "kill -9" does not work with the current
version of EMX.
o See "Text-mode filehandles".
o Unix-domain sockets on OS/2 live in a pseudo-file-sys-
tem "/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
this already).
This may lead to problems later in case the socket is
accessed via the "usual" file-system calls using the
"initial" name.
o Apparently, IBM used a compiler (for some period of
time around '95?) which changes FP mask right and
left. This is not that bad for IBM's programs, but
the same compiler was used for DLLs which are used
with general-purpose applications. When these DLLs
are used, the state of floating-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 call any function
in the DLL, just the act of loading this DLL will
reset your flags. 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 applica-
tions in the system, this means a complete unpre-
dictablity of floating point flags on systems using
such HOOK DLLs. E.g., GAMESRVR.DLL of DIVE origin
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 include some 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-point exceptions 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 of damage only: FP flags changed when
loading a DLL.
One of the hacks is to disable floating point excep-
tions on Perl startup (as is the default with EMX).
This helps only with compile-time-linked DLLs changing
the flags before main() had a chance to be called.
The other hack is to restore FP flags after a call to
dlopen(). This helps against similar damage done by
DLLs _DLLInitTerm() at runtime. Currently no way to
switch these hacks off is provided.
Modifications
Perl modifies some standard C library calls in the follow-
ing ways:
"popen" "my_popen" uses sh.exe if shell is required, cf.
"PERL_SH_DIR".
"tmpnam" is created using "TMP" or "TEMP" environment
variable, via "tempnam".
"tmpfile"
If the current directory is not writable, file is
created using modified "tmpnam", 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 con-
tains 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 variable
"USE_PERL_FLOCK=0".
Identifying DLLs
All the DLLs built with the current versions of Perl have
ID strings identifying the name of the extension, its ver-
sion, and the version of Perl required for this DLL. Run
"bldlevel DLL-name" to find this info.
Centralized management of resources
Since to call certain OS/2 API one needs to have a cor-
rectly initialized "Win" subsystem, OS/2-specific exten-
sions may require getting "HAB"s and "HMQ"s. If an exten-
sion would do it on its own, another extension could fail
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. After this call is performed,
"hab" may be accessed as "Perl_hab". There is no need
to release the HAB after it is used.
If by some reasons perl.h cannot be included, use
extern int Perl_hab_GET(void);
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 per-
formed, "hmq" may be accessed as "Perl_hmq".
To signal to Perl that HMQ is not needed any more,
call "perl_hmq_UNSET(serve)". Perl process will auto-
matically morph/unmorph itself into/from a PM process
if HMQ is needed/not-needed. Perl will automatically
enable/disable "WM_QUIT" message during shutdown if
the message queue is served/not-served.
NOTE. If during a shutdown there is a message queue
which did not disable WM_QUIT, and which did not pro-
cess the received WM_QUIT message, the shutdown will
be automatically cancelled. Do not call
perl_hmq_GET(1) unless you are going to process mes-
sages 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 always determined by the
name of the API) of reporting the error conditions of
OS/2 API. Most of "Dos*" APIs report the error code
as the result of the call (so 0 means success, and
there are many types of errors). Most of "Win*" API
report success/fail via the result being
"TRUE"/"FALSE"; to find the reason for the failure one
should call WinGetLastError() API.
Some "Win*" entry points also overload a "meaningful"
return value with the error indicator; having a 0
return value indicates an error. Yet some other
"Win*" entry points overload things even more, and 0
return value may mean a successful call returning a
valid value 0, as well as an error condition; in the
case of a 0 return value one should call WinGetLastEr-
ror() API to distinguish a successful call from a
failing one.
By convention, all the calls to OS/2 API should indi-
cate their failures by resetting $^E. All the Perl-
accessible functions which call OS/2 API may be broken
into two classes: some die()s when an API error is
encountered, the other report the error via a false
return value (of course, this does not concern Perl-
accessible functions which expect a failure of the
OS/2 API call, having some workarounds coded).
Obviously, in the situation of the last type of the
signature of an OS/2 API, it is must more convenient
for the users if the failure is indicated by die()ing:
one does not need to check $^E to know that something
went wrong. If, however, this solution is not desir-
able by some reason, the code in question should reset
$^E to 0 before making this OS/2 API call, so that the
caller of this Perl-accessible function has a chance
to distinguish a success-but-0-return value from a
failure. (One may return undef as an alternative way
of reporting an error.)
The macros to simplify this type of error propagation
are
"CheckOSError(expr)"
Returns true on error, sets $^E. Expects expr()
be a call of "Dos*"-style API.
"CheckWinError(expr)"
Returns true on error, sets $^E. Expects expr()
be a call of "Win*"-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 the concatenated
strings "name1" and "name2", separated by ": "
from the contents of $^E.
"WinError_2_Perl_rc"
Sets "Perl_rc" to the return value of WinGet-
LastError().
"FillWinError"
Sets "Perl_rc" to the return value of WinGet-
LastError(), and sets $^E to the corresponding
value.
"FillOSError(rc)"
Sets "Perl_rc" to "rc", and sets $^E to the corre-
sponding value.
* Loading DLLs and ordinals in DLLs
Some DLLs are only present in some versions of OS/2,
or in some configurations of OS/2. Some exported
entry points are present only in DLLs shipped with
some versions of OS/2. If these DLLs and entry points
were linked directly for a Perl executable/DLL or from
a Perl extensions, this binary would work only with
the specified versions/setups. Even if these entry
points were not needed, the load of the executable (or
DLL) would fail.
For example, many newer useful APIs are not present in
OS/2 v2; many PM-related APIs require DLLs not avail-
able on floppy-boot setup.
To make these calls fail only when the calls are exe-
cuted, one should call these API via a dynamic linking
API. There is a subsystem in Perl to simplify such
type of calls. A large number of entry points avail-
able for such linking is provided (see "entries_ordi-
nals" - and also "PMWIN_entries" - in os2ish.h).
These ordinals can be accessed via the APIs:
CallORD(), DeclFuncByORD(), DeclVoidFuncByORD(),
DeclOSFuncByORD(), DeclWinFuncByORD(), AssignFuncPByORD(),
DeclWinFuncByORD_CACHE(), DeclWinFuncByORD_CACHE_survive(),
DeclWinFuncByORD_CACHE_resetError_survive(),
DeclWinFunc_CACHE(), DeclWinFunc_CACHE_resetError(),
DeclWinFunc_CACHE_survive(), DeclWinFunc_CACHE_resetError_survive()
See the header files and the C code in the supplied
OS/2-related modules for the details on usage of these
functions.
Some of these functions also combine dynaloading
semantic with the error-propagation semantic discussed
above.
Perl flavors
Because of idiosyncrasies of OS/2 one cannot have all the
eggs in the same basket (though EMX environment tries hard
to overcome this limitations, so the situation may somehow
improve). There are 4 executables for Perl provided by the
distribution:
perl.exe
The main workhorse. This is a chimera executable: it is
compiled as an "a.out"-style executable, but is linked
with "omf"-style dynamic library perl.dll, and with
dynamic CRT DLL. This executable is a VIO 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
cannot load dynamic Perl extensions. The executable sup-
plied in binary distributions has a lot of extensions pre-
built, thus the above restriction is important only if you
use custom-built extensions. This executable is a VIO
application.
This is the only executable with does not require OS/2.
The friends locked into "M$" world would appreciate the
fact that this executable runs under DOS, Win0.3*, Win0.95
and WinNT with an appropriate extender. See "Other OSes".
perl__.exe
This is the same executable as perl___.exe, but it is a PM
application.
Note. Usually (unless explicitly redirected during the
startup) STDIN, STDERR, and STDOUT of a PM application are
redirected to nul. However, it is possible to see them if
you start "perl__.exe" from a PM program which emulates a
console window, like Shell mode of Emacs or EPM. Thus it
is possible to use Perl debugger (see perldebug) to debug
your PM application (but beware of the message loop lock-
ups - this will not work if you have a message queue to
serve, unless you hook the serving into the getc() func-
tion of the debugger).
Another way to see the output of a PM program is to run it
as
pm_prog args 2>&1 | cat -
with a shell different from cmd.exe, so that it does not
create a link between a VIO session and the session of
"pm_porg". (Such a link closes the VIO window.) E.g.,
this works with sh.exe - or with Perl!
open P, 'pm_prog args 2>&1 |' or die;
print while ;
The flavor perl__.exe is required if you want to start
your program without a VIO window present, but not
"detach"ed (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 executa-
bles are only in the default behaviour. One can start any
executable in any kind of session by using the arguments
"/fs", "/pm" or "/win" switches of the command "start" (of
CMD.EXE or a similar shell). Alternatively, one can use
the numeric first argument of the "system" Perl function
(see OS2::Process).
perl___.exe
This is an "omf"-style executable which is dynamically
linked to perl.dll and CRT DLL. I know no advantages of
this executable over "perl.exe", but it cannot fork() at
all. Well, one advantage is that 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, "Switches" in perlrun, "Not a perl script" in
perldiag, "No Perl script found in input" in perldiag), it
should know when a program is a Perl. There is some naming
convention which allows Perl to distinguish correct lines
from wrong ones. The above names are almost the only names
allowed by this convention which do not contain digits
(which have absolutely different semantics).
Why dynamic linking?
Well, having several executables dynamically linked to the
same huge library has its advantages, but this would not
substantiate the additional work to make it compile. The
reason is the complicated-to-developers but 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 func-
tions 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 avoids conflicts when several DLLs used
by an application export entries with the same name. In
such cases "other" models of dyna-linking just choose
between these two entry points using some random criterion
- with predictable disasters as results. But it is the
second feature which requires the build of perl.dll.
The address tables of DLLs are patched only once, when
they are loaded. The addresses of the entry points into
DLLs are guaranteed to be the same for all the programs
which use the same DLL. This removes the runtime fixup -
once DLL is loaded, its code is read-only.
While this allows some (significant?) performance advan-
tages, this makes life much harder for developers, since
the above scheme makes it impossible for a DLL to be
"linked" to a symbol in the .EXE file. Indeed, this would
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 symbols from the perl executable, e.g., to know
how to find the arguments to the functions: the arguments
live on the perl internal evaluation stack. The solution
is to put the main code of the interpreter into a DLL, and
make the .EXE file which just loads this DLL into memory
and supplies command-arguments. The extension DLL cannot
link to symbols in .EXE, but it has no problem linking to
symbols in the .DLL.
This greatly increases the load time for the application
(as well as complexity of the compilation). Since inter-
preter is in a DLL, the C RTL is basically forced to
reside in a DLL as well (otherwise extensions would not be
able to use CRT). There are some advantages if you use
different flavors of perl, such as running perl.exe and
perl__.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 resource given 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 sections of the .EXE file
are loaded is decided at compile-time, thus all the pro-
cesses have these sections loaded at same addresses, and
no fixup of internal links inside the .EXE is needed.
Since DLLs may be loaded at run time, to have the same
mechanism for DLLs one needs to have the address range of
any of the loaded DLLs in the system to be available in
all the processes which did not load a particular DLL 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
Unixish "a.out" format to export symbols for data (or at
least some types of data). This forces "omf"-style compile
of perl.dll.
Current EMX environment does not allow .EXE files compiled
in "omf" format to fork(). fork() is needed for exactly
three Perl operations:
o explicit fork() in the script,
o "open FH, "|-""
o "open FH, "-|"", in other words, opening pipes to
itself.
While these operations are not questions of life and
death, they are needed for a lot of useful scripts. This
forces "a.out"-style compile of perl.exe.
ENVIRONMENT
Here we list environment variables with are either OS/2-
and DOS- and Win*-specific, or are more important under
OS/2 than under other OSes.
"PERLLIB_PREFIX"
Specific for EMX port. Should have the form
path1;path2
or
path1 path2
If the beginning of some prebuilt path matches path1, it
is substituted with path2.
Should be used if the perl library is moved from the
default location in preference to "PERL(5)LIB", since this
would not leave wrong entries in @INC. For example, if
the compiled version of perl looks for @INC in f:/perl-
lib/lib, and you want to install the library in
h:/opt/gnu, do
set PERLLIB_PREFIX=f:/perllib/lib;h:/opt/gnu
This will cause Perl with the prebuilt @INC of
f:/perllib/lib/5.00553/os2
f:/perllib/lib/5.00553
f:/perllib/lib/site_perl/5.00553/os2
f:/perllib/lib/site_perl/5.00553
.
to use the following @INC:
h:/opt/gnu/5.00553/os2
h:/opt/gnu/5.00553
h:/opt/gnu/site_perl/5.00553/os2
h:/opt/gnu/site_perl/5.00553
.
"PERL_BADLANG"
If 0, perl ignores setlocale() failing. May be useful with
some strange locales.
"PERL_BADFREE"
If 0, perl would not warn of in case of unwarranted
free(). With older perls this might be useful in conjunc-
tion with the module DB_File, which was buggy when dynami-
cally 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 for sh.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 sur-
prise.
Text-mode filehandles
Starting from version 5.8, Perl uses a builtin translation
layer for text-mode files. This replaces the efficient
well-tested EMX layer by some code which should be best
characterized as a "quick hack".
In addition to possible bugs and an inability to follow
changes to the translation policy with off/on switches of
TERMIO translation, this introduces a serious incompatible
change: before sysread() on text-mode filehandles would go
through the translation layer, now it would not.
Priorities
"setpriority" and "getpriority" are not compatible with
earlier ports by Andreas Kaiser. See "setpriority, getpri-
ority".
DLL name mangling: pre 5.6.2
With the release 5.003_01 the dynamically loadable
libraries should be rebuilt when a different version of
Perl is compiled. In particular, DLLs (including perl.dll)
are now created with the names which contain a checksum,
thus allowing workaround for OS/2 scheme of caching DLLs.
It may be possible to code a simple workaround which would
o find the old DLLs looking through the old @INC;
o mangle the names according to the scheme of new perl
and copy the DLLs to these names;
o 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 names are
not used for "specific" DLLs, they used only for
"global" DLLs).
o 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 misun-
derstanding of the OS/2 dynaloading model. OS/2 (effec-
tively) maintains two different tables of loaded DLL:
Global DLLs
those loaded by the base name from "LIBPATH"; includ-
ing those associated at link time;
specific DLLs
loaded by the full name.
When resolving a request for a global DLL, the table of
already-loaded specific DLLs is (effectively) ignored;
moreover, specific DLLs are always loaded from the pre-
scribed path.
There is/was a minor twist which makes this scheme frag-
ile: what to do with DLLs loaded from
"BEGINLIBPATH" and "ENDLIBPATH"
(which depend on the process)
. from "LIBPATH"
which effectively depends on the process (although
"LIBPATH" is the same for all the processes).
Unless "LIBPATHSTRICT" is set to "T" (and the kernel is
after 2000/09/01), such DLLs are considered to be global.
When loading a global DLL it is first looked in the table
of already-loaded global DLLs. Because of this the fact
that one executable loaded a DLL from "BEGINLIBPATH" and
"ENDLIBPATH", or . from "LIBPATH" may affect which DLL is
loaded when another executable requests a DLL with the
same name. This is the reason for version-specific man-
gling of the 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 the
same as for Perl 5.005_53 (same as in a popular binary
release). Thus new Perls will be able to resolve the
names of old extension DLLs if @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 since the extension DLLs link with the Perl
DLL, extension DLLs for older versions would load an older
Perl DLL, and would most probably segfault (since the data
in this DLL is not properly initialized).
There is a partial workaround (which can be made complete
with newer OS/2 kernels): create a forwarder DLL with the
same name as the DLL of the older version of Perl, which
forwards the entry points to the newer Perl's DLL. Make
this DLL accessible on (say) the "BEGINLIBPATH" of the new
Perl executable. When the new executable accesses old
Perl's extension DLLs, they would request the old Perl's
DLL by name, get the forwarder instead, so effectively
will link with the currently running (new) Perl DLL.
This may break in two ways:
o Old perl executable is started when a new executable
is running has loaded an extension compiled for the
old executable (ouph!). In this case the old exe-
cutable will get a forwarder DLL instead of the old
perl DLL, so would link with the new perl DLL. While
not directly fatal, it will behave the same as new
executable. This beats the whole purpose of explic-
itly starting an old executable.
o A new executable loads an extension compiled for the
old executable when an old perl executable is running.
In this case the extension will not pick up the for-
warder - with fatal results.
With support for "LIBPATHSTRICT" this may be circumvented
- unless one of DLLs is started from . from "LIBPATH" (I
do not know whether "LIBPATHSTRICT" affects this case).
REMARK. Unless newer kernels allow . in "BEGINLIBPATH"
(older do not), this mess cannot be completely cleaned.
(It turns out that as of the beginning of 2002, . is not
allowed, but .\. is - and it has the same effect.)
REMARK. "LIBPATHSTRICT", "BEGINLIBPATH" and "ENDLIBPATH"
are not environment variables, although cmd.exe emulates
them on "SET ..." lines. From Perl they may be accessed
by Cwd::extLibpath and Cwd::extLibpath_set.
DLL forwarder generation
Assume that the old DLL is named perlE0AC.dll (as is one
for 5.005_53), and the new version is 5.6.1. Create a
file perl5shim.def-leader with
LIBRARY 'perlE0AC' INITINSTANCE TERMINSTANCE
DESCRIPTION '@#perl5-porters@perl.org:5.006001#@ Perl module for 5.00553 -> Perl 5.6.1 forwarder'
CODE LOADONCALL
DATA LOADONCALL NONSHARED MULTIPLE
EXPORTS
modifying the versions/names as needed. Run
perl -wnle "next if 0../EXPORTS/; print qq( \"$1\") if /\"(\w+)\"/" perl5.def >lst
in the Perl build directory (to make the DLL smaller
replace perl5.def with the definition file for the older
version of Perl if present).
cat perl5shim.def-leader lst >perl5shim.def
gcc -Zomf -Zdll -o perlE0AC.dll perl5shim.def -s -llibperl
(ignore multiple "warning L4085").
Threading
As of release 5.003_01 perl is linked to multithreaded C
RTL DLL. If perl itself is not compiled multi-
thread-enabled, so will not be perl's malloc(). However,
extensions may use multiple thread on their own risk.
This was needed to compile "Perl/Tk" for XFree86-OS/2
out-of-the-box, and link with DLLs for other useful
libraries, which typically are compiled with "-Zmt -Zcrt-
dll".
Calls to external programs
Due to a popular demand the perl external program calling
has been changed wrt Andreas Kaiser's port. If perl needs
to call an external program via shell, the f:/bin/sh.exe
will be called, or whatever is the override, see
"PERL_SH_DIR".
Thus means that you need to get some copy of a sh.exe as
well (I use one from pdksh). The path F:/bin above is set
up automatically during the build to a correct value on
the builder machine, but is overridable at runtime,
Reasons: a consensus on "perl5-porters" was that perl
should use one non-overridable shell per platform. The
obvious choices for OS/2 are cmd.exe and sh.exe. Having
perl build itself would be impossible with cmd.exe as a
shell, thus I picked up "sh.exe". This assures almost 100%
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
programs via fork()/exec(), and there is no functioning
exec() on OS/2. exec() is emulated by EMX by an asyn-
chronous call while the caller waits for child completion
(to pretend that the "pid" did not change). This means
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 do not count extra work needed for
fork()ing).
Note that this a lesser issue now when we do not spawn
sh.exe unless needed (metachars found).
One can always start cmd.exe explicitly via
system 'cmd', '/c', 'mycmd', 'arg1', 'arg2', ...
If you need to use cmd.exe, and do not want to hand-edit
thousands of your scripts, the long-term solution proposed
on p5-p is to have a directive
use OS2::Cmd;
which will override system(), exec(), ``, and
"open(,'...|')". With current perl you may override only
system(), readpipe() - the explicit version of ``, and
maybe exec(). The code will substitute the one-argument
call to system() by "CORE::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, so cannot 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 couple of features:
o External scripts may be called by their basename.
Perl will try the same extensions as when processing
-S command-line switch.
o External scripts starting with "#!" or "extproc " will
be executed directly, without calling the shell, by
calling the program specified on the rest of the first
line.
Memory allocation
Perl uses its own malloc() under OS/2 - interpreters are
usually malloc-bound for speed, but perl is not, since its
malloc is lightning-fast. Perl-memory-usage-tuned bench-
marks show that Perl's malloc is 5 times quicker than EMX
one. I do not have convincing data about memory foot-
print, but a (pretty random) benchmark showed that Perl's
one is 5% better.
Combination of perl's malloc() and rigid DLL name resolu-
tion creates a special problem with library functions
which expect their return value to be free()d by system's
free(). To facilitate extensions which need to call such
functions, system memory-allocation functions are still
available with the 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 provid-
ing "-D usethreads" option 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-triggered nature of OS/2 Event semaphores).
(Needs a reimplementation (in terms of chaining wait-
ing 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 be moved to per-thread structure,
or serialized?)
Note that these problems should not discourage experiment-
ing, since they have a low probability of affecting small
programs.
BUGS
This description is not updated often (since 5.6.1?), see
./os2/Changes (perlos2delta) for more info.
AUTHOR
Ilya Zakharevich, cpan@ilyaz.org
SEE ALSO
perl(1).
perl v5.8.8 2006-01-07 PERLOS2(1)