in F<?:\JUST_ADD\view.exe>. This gives one an access to EMX's
F<.INF> docs as well (text form is available in F</emx/doc> in
-EMX's distribution).
+EMX's distribution). There is also a different viewer named xview.
-Note that if you have F<lynx.exe> installed, you can follow WWW links
+Note that if you have F<lynx.exe> or F<netscape.exe> installed, you can follow WWW links
from this document in F<.INF> format. If you have EMX docs installed
correctly, you can follow library links (you need to have C<view emxbook>
working by setting C<EMXBOOK> environment variable as it is described
=cut
-Contents
+Contents (This may be a little bit obsolete)
perlos2 - Perl under OS/2, DOS, Win0.3*, Win0.95 and WinNT.
- NAME
- SYNOPSIS
- DESCRIPTION
- - Target
- - Other OSes
- - Prerequisites
- - Starting Perl programs under OS/2 (and DOS and...)
- - Starting OS/2 (and DOS) programs under Perl
- Frequently asked questions
- - I cannot run external programs
- - I cannot embed perl into my program, or use perl.dll from my program.
- - `` and pipe-open do not work under DOS.
- - Cannot start find.exe "pattern" file
- INSTALLATION
- - Automatic binary installation
- - Manual binary installation
- - Warning
- Accessing documentation
- - OS/2 .INF file
- - Plain text
- - Manpages
- - HTML
- - GNU info files
- - .PDF files
- - LaTeX docs
- BUILD
- - Prerequisites
- - Getting perl source
- - Application of the patches
- - Hand-editing
- - Making
- - Testing
- - Installing the built perl
- - a.out-style build
- Build FAQ
- - Some / became \ in pdksh.
- - 'errno' - unresolved external
- - Problems with tr
- - Some problem (forget which ;-)
- - Library ... not found
- - Segfault in make
- Specific (mis)features of EMX port
- - setpriority, getpriority
- - system()
- - extproc on the first line
- - Additional modules:
- - Prebuilt methods:
- - Misfeatures
- - Modifications
- Perl flavors
- - perl.exe
- - perl_.exe
- - perl__.exe
- - perl___.exe
- - Why strange names?
- - Why dynamic linking?
- - Why chimera build?
- ENVIRONMENT
- - PERLLIB_PREFIX
- - PERL_BADLANG
- - PERL_BADFREE
- - PERL_SH_DIR
- - TMP or TEMP
- Evolution
- - Priorities
- - DLL name mangling
- - Threading
- - Calls to external programs
- - Memory allocation
- - Threads
- AUTHOR
- SEE ALSO
+ NAME
+ SYNOPSIS
+ DESCRIPTION
+ - Target
+ - Other OSes
+ - Prerequisites
+ - Starting Perl programs under OS/2 (and DOS and...)
+ - Starting OS/2 (and DOS) programs under Perl
+ Frequently asked questions
+ - "It does not work"
+ - I cannot run external programs
+ - I cannot embed perl into my program, or use perl.dll from my
+ - `` and pipe-open do not work under DOS.
+ - Cannot start find.exe "pattern" file
+ INSTALLATION
+ - Automatic binary installation
+ - Manual binary installation
+ - Warning
+ Accessing documentation
+ - OS/2 .INF file
+ - Plain text
+ - Manpages
+ - HTML
+ - GNU info files
+ - PDF files
+ - LaTeX docs
+ BUILD
+ - The short story
+ - Prerequisites
+ - Getting perl source
+ - Application of the patches
+ - Hand-editing
+ - Making
+ - Testing
+ - Installing the built perl
+ - a.out-style build
+ Build FAQ
+ - Some / became \ in pdksh.
+ - 'errno' - unresolved external
+ - Problems with tr or sed
+ - Some problem (forget which ;-)
+ - Library ... not found
+ - Segfault in make
+ - op/sprintf test failure
+ Specific (mis)features of OS/2 port
+ - setpriority, getpriority
+ - system()
+ - extproc on the first line
+ - Additional modules:
+ - Prebuilt methods:
+ - Prebuilt variables:
+ - Misfeatures
+ - Modifications
+ - Identifying DLLs
+ - Centralized management of resources
+ Perl flavors
+ - perl.exe
+ - perl_.exe
+ - perl__.exe
+ - perl___.exe
+ - Why strange names?
+ - Why dynamic linking?
+ - Why chimera build?
+ ENVIRONMENT
+ - PERLLIB_PREFIX
+ - PERL_BADLANG
+ - PERL_BADFREE
+ - PERL_SH_DIR
+ - USE_PERL_FLOCK
+ - TMP or TEMP
+ Evolution
+ - Text-mode filehandles
+ - Priorities
+ - DLL name mangling: pre 5.6.2
+ - DLL name mangling: 5.6.2 and beyond
+ - DLL forwarder generation
+ - Threading
+ - Calls to external programs
+ - Memory allocation
+ - Threads
+ BUGS
+ AUTHOR
+ SEE ALSO
=head1 DESCRIPTION
=head2 Target
-The target is to make OS/2 the best supported platform for
+The target is to make OS/2 one of the best supported platform for
using/building/developing Perl and I<Perl applications>, 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 B<too> hard).
=item *
-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;
-some flavors do not. Using fork() after I<use>ing dynamically loading
-extensions would not work with very old versions of EMX.
+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
+I<use>ing dynamically loading extensions would not work with I<very> old
+versions of EMX.
=item *
=item *
There is no simple way to access WPS objects. The only way I know
-is via C<OS2::REXX> extension (see L<OS2::REXX>), and we do not have access to
+is via C<OS2::REXX> and C<SOM> extensions (see L<OS2::REXX>, L<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 C<SOM> extension (currently in alpha-text)
-may eventually remove this shortcoming.
+may eventually remove this shortcoming; however, due to the fact that
+DII is not supported by the C<SOM> module, using C<SOM> is not as
+convenient as one would like it.
=back
that under DOS for best results one should use RSX runtime, which
has much more functions working (like C<fork>, C<popen> and so on). In
fact RSX is required if there is no VCPI present. Note the
-RSX requires DPMI.
+RSX requires DPMI. Many implementations of DPMI are known to be very
+buggy, beware!
Only the latest runtime is supported, currently C<0.9d fix 03>. Perl may run
under earlier versions of EMX, but this is not tested.
The runtime component should have the name F<emxrt.zip>.
-B<NOTE>. It is enough to have F<emx.exe>/F<rsx.exe> on your path. One
+B<NOTE>. When using F<emx.exe>/F<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
The latest F<sh.exe> with DOS hooks is available in
- ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/
+ http://www.ilyaz.org/software/os2/
as F<sh_dos.zip> or under similar names starting with C<sh>, C<pdksh> etc.
=item HPFS
-Perl does not care about file systems, but to install the whole perl
-library intact one needs a file system which supports long file names.
+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 supports 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,
For best results use EMX pdksh. The standard binary (5.2.14 or later) runs
under DOS (with L<RSX>) as well, see
- ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/
+ http://www.ilyaz.org/software/os2/
=back
*nixish shell (like F<sh.exe> supplied in the binary distribution),
you need to follow the syntax specified in L<perlrun/"Switches">.
-Note that B<-S> switch enables a search with additional extensions
+Note that B<-S> switch supports scripts with additional extensions
F<.cmd>, F<.btm>, F<.bat>, F<.pl> as well.
=head2 Starting OS/2 (and DOS) programs under Perl
=item 6
If the executable called by system()/exec()/pipe-open()/C<``> is not
-found;
+found (is not this remark obsolete?);
=item 7
-For globbing (see L<perlfunc/glob>, L<perlop/"I/O Operators">).
+For globbing (see L<perlfunc/glob>, L<perlop/"I/O Operators">)
+(obsolete? Perl uses builtin globbing nowadays...).
=back
Perl starts scripts which begin with cookies
C<extproc> or C<#!> directly, without an intervention of shell. Perl uses the
same algorithm to find the executable as F<pdksh>: if the path
-on C<#!> line does not work, and contains C</>, then the executable
+on C<#!> line does not work, and contains C</>, then the directory
+part of the executable is ignored, and the executable
is searched in F<.> and on C<PATH>. To find arguments for these scripts
Perl uses a different algorithm than F<pdksh>: up to 3 arguments are
recognized, and trailing whitespace is stripped.
C<$ENV{COMSPEC} /c> is used (or a hardwired guess if C<$ENV{COMSPEC}> is
not set).
-If starting scripts directly, Perl will use exactly the same algorithm as for
+When starting scripts directly, Perl uses exactly the same algorithm as for
the search of script given by B<-S> command-line option: it will look in
the current directory, then on components of C<$ENV{PATH}> using the
following order of appended extensions: no extension, F<.cmd>, F<.btm>,
Note that Perl will start to look for scripts only if OS/2 cannot start the
specified application, thus C<system 'blah'> will not look for a script if
-there is an executable file F<blah.exe> I<anywhere> on C<PATH>.
+there is an executable file F<blah.exe> I<anywhere> on C<PATH>. In
+other words, C<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 arbitrary extension,
but F<.exe> will be automatically appended if no dot is present in the name.
The workaround is as simple as that: since F<blah.> and F<blah> denote the
-same file, to start an executable residing in file F<n:/bin/blah> (no
+same file (at list on FAT and HPFS file systems), to start an executable residing in file F<n:/bin/blah> (no
extension) give an argument C<n:/bin/blah.> (dot appended) to system().
-Perl will correctly start PM programs from VIO (=text-mode) Perl process;
+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 process, it would not run it in a separate session. If a separate
+Perl process, Perl would not run it in a separate session. If a separate
session is desired, either ensure
that shell will be used, as in C<system 'cmd /c myprog'>, or start it using
optional arguments to system() documented in C<OS2::Process> module. This
=item Is your program EMX-compiled with C<-Zmt -Zcrtdll>?
-If not, 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.
+Well, nowadays Perl DLL should be usable from a differently compiled
+program too... If you can run Perl code from REXX scripts (see
+L<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.
=item Did you use L<ExtUtils::Embed>?
-I had reports it does not work. Somebody would need to fix it.
+Some time ago I had reports it does not work. Nowadays it is checked
+in the Perl test suite, so grep F<./t> subdirectory of the build tree
+(as well as F<*.t> files in the F<./lib> subdirectory) to find how it
+should be done "correctly".
=back
=head2 Cannot start C<find.exe "pattern" file>
+The whole idea of the "standard C API to start applications" is that
+the forms C<foo> and C<"foo"> of program arguments are completely
+interchangable. F<find> breaks this paradigm;
+
+ find "pattern" file
+ find pattern file
+
+are not equivalent; F<find> cannot be started directly using the above
+API. One needs a way to surround the doublequotes in some other
+quoting construction, necessarily having an extra non-Unixish shell in
+between.
+
Use one of
system 'cmd', '/c', 'find "pattern" file';
This would start F<find.exe> via F<cmd.exe> via C<sh.exe> via
C<perl.exe>, but this is a price to pay if you want to use
-non-conforming program. In fact F<find.exe> cannot be started at all
-using C library API only. Otherwise the following command-lines would be
-equivalent:
-
- find "pattern" file
- find pattern file
+non-conforming program.
=head1 INSTALLATION
emxrev
-A folder is created on your desktop which contains some useful
-objects.
+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 F<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.
B<Things not taken care of by automatic binary installation:>
While most important values in this file I<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.
+data, please keep me informed if you find one. Moreover, manual
+changes to the installed version may need to be accompanied by an edit
+of this file.
=back
need to know where to extract the files. You need also to manually
change entries in F<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
+C<pkunzip>), you may get a lot of warnings/errors during
unzipping. Upgrade to C<(w)unzip>.
Below is the sample of what to do to reproduce the configuration on my
-machine:
+machine. In F<VIEW.EXE> you can press C<Ctrl-Insert> now, and
+cut-and-paste from the resulting file - created in the directory you
+started F<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 create/append-to variables to take into
+account the directories.
=over 3
variable. Do not use C<PERL5LIB> unless you have it set already. See
L<perl/"ENVIRONMENT">.
+B<[Check whether this extraction directory is still applicable with
+the new directory structure layout!]>
+
=item Tools to compile Perl modules
unzip perl_blb.zip -d f:/perllib/lib
unzip perl_man.zip -d f:/perllib/man
This directory should better be on C<MANPATH>. You need to have a
-working man to access these files.
+working F<man> to access these files.
=item Manpages for Perl modules
This is used by the C<perldoc> program (see L<perldoc>), and may be used to
generate HTML documentation usable by WWW browsers, and
documentation in zillions of other formats: C<info>, C<LaTeX>,
-C<Acrobat>, C<FrameMaker> and so on.
+C<Acrobat>, C<FrameMaker> and so on. [Use programs such as
+F<pod2latex> etc.]
=item Perl manual in F<.INF> format
Set C<PERL_SH_DIR> (see L<"PERL_SH_DIR">) if you move F<sh.exe> from
the above location.
-B<Note.> It may be possible to use some other sh-compatible shell
-(file globbing - if done via shell - may break).
+B<Note.> It may be possible to use some other sh-compatible shell (untested).
=back
The automatic and manual perl installation leave precompiled paths
inside perl executables. While these paths are overwriteable (see
-L<"PERLLIB_PREFIX">, L<"PERL_SH_DIR">), one may get better results by
+L<"PERLLIB_PREFIX">, L<"PERL_SH_DIR">), some people may prefer
binary editing of paths inside the executables/DLLs.
=head1 Accessing documentation
=head2 Manpages
-If you have man installed on your system, and you installed perl
+If you have F<man> installed on your system, and you installed perl
manpages, use something like this:
man perlfunc
=head2 GNU C<info> files
Users of Emacs would appreciate it very much, especially with
-C<CPerl> mode loaded. You need to get latest C<pod2info> from C<CPAN>,
-or, alternately, prebuilt info pages.
+C<CPerl> mode loaded. You need to get latest C<pod2texi> from C<CPAN>,
+or, alternately, the prebuilt info pages.
=head2 F<PDF> files
-for C<Acrobat> are available on CPAN (for slightly old version of
+for C<Acrobat> are available on CPAN (may be for slightly older version of
perl).
=head2 C<LaTeX> docs
=head1 BUILD
Here we discuss how to build Perl under OS/2. There is an alternative
-(but maybe older) view on http://www.shadow.net/~troc/os2perl.html
+(but maybe older) view on L<http://www.shadow.net/~troc/os2perl.html>.
=head2 The short story
make aout_install
This puts the executables in f:/perllib/bin. Manually move them to the
-C<PATH>, manually move the built F<perl*.dll> to C<LIBPATH> (here F<*> is
-a not-very-meaningful hex checksum), and run
+C<PATH>, manually move the built F<perl*.dll> to C<LIBPATH> (here for
+Perl DLL F<*> is a not-very-meaningful hex checksum), and run
make installcmd INSTALLCMDDIR=d:/ir/on/path
+Assuming that the C<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.
=head2 Prerequisites
Check that you have B<BSD> libraries and headers installed, and -
optionally - Berkeley DB headers and libraries, and crypt.
-Possible locations to get this from are
+Possible locations to get the files:
ftp://hobbes.nmsu.edu/os2/unix/
ftp://ftp.cdrom.com/pub/os2/unix/
It is reported that the following archives contain enough utils to
build perl: F<gnufutil.zip>, F<gnusutil.zip>, F<gnututil.zip>, F<gnused.zip>,
-F<gnupatch.zip>, F<gnuawk.zip>, F<gnumake.zip>, F<bsddev.zip> and
+F<gnupatch.zip>, F<gnuawk.zip>, F<gnumake.zip>, F<gnugrep.zip>, F<bsddev.zip> and
F<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 F<db.lib> and F<db.a> from the EMX distribution
+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 I<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 F<perl.dll> loaded into
and F<.> directory in your C<LIBPATH>. One may try to correct the
latter condition by
- set BEGINLIBPATH .
+ set BEGINLIBPATH .\.
-if you use something like F<CMD.EXE> or latest versions of F<4os2.exe>.
+if you use something like F<CMD.EXE> or latest versions of
+F<4os2.exe>. (Setting BEGINLIBPATH to just C<.> is ignored by the
+OS/2 kernel.)
Make sure your gcc is good for C<-Zomf> linking: run C<omflibs>
script in F</emx/lib> directory.
gnupatch -p0 < os2\diff.configure
You may also need to apply the patches supplied with the binary
-distribution of perl.
-
-Note also that the F<db.lib> and F<db.a> from the EMX distribution
-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
-
- ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/db_mt.zip
+distribution of perl. It also makes sense to look on the
+perl5-porters mailing list for the latest OS/2-related patches (see
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/>). Such
+patches usually contain strings C</os2/> and C<patch>, so it makes
+sense looking for these strings.
=head2 Hand-editing
make test
-All tests should succeed (with some of them skipped).
+All tests should succeed (with some of them skipped). If you have the
+same version of Perl installed, it is crucial that you have C<.> early
+in your LIBPATH (or in BEGINLIBPATH), otherwise your tests will most
+probably test the wrong version of Perl.
Some tests may generate extra messages similar to
=head2 Installing the built perl
-If you haven't yet moved perl.dll onto LIBPATH, do it now.
+If you haven't yet moved C<perl*.dll> onto LIBPATH, do it now.
Run
installed in C<$prefix/bin>, here C<$prefix> is what you gave to
F<Configure>, see L<Making>.
+If you use C<man>, either move the installed F<*/man/> directories to
+your C<MANPATH>, or modify C<MANPATH> to match the location. (One
+could have avoided this by providing a correct C<manpath> option to
+F<./Configure>, or editing F<./config.sh> between configuring and
+making steps.)
+
=head2 C<a.out>-style build
Proceed as above, but make F<perl_.exe> (see L<"perl_.exe">) by
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 different type than the
-current session, it will start the new process in a separate session of
+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 C<OS2::Process> to disable this magic.
B<WARNING>. Due to the described logic, you need to explicitly
Two additional extensions by Andreas Kaiser, C<OS2::UPM>, and
C<OS2::FTP>, are included into C<ILYAZ> directory, mirrored on CPAN.
+Other OS/2-related extensions are available too.
=head2 Prebuilt methods:
=item C<Cwd::extLibpath([type])>
Get current value of extended library search path. If C<type> is
-present and I<true>, works with END_LIBPATH, otherwise with
-C<BEGIN_LIBPATH>.
+present and positive, works with C<END_LIBPATH>, if negative, works
+with C<LIBPATHSTRICT>, otherwise with C<BEGIN_LIBPATH>.
=item C<Cwd::extLibpath_set( path [, type ] )>
Set current value of extended library search path. If C<type> is
-present and I<true>, works with END_LIBPATH, otherwise with
-C<BEGIN_LIBPATH>.
+present and positive, works with <END_LIBPATH>, if negative, works
+with C<LIBPATHSTRICT>, otherwise with C<BEGIN_LIBPATH>.
=item C<OS2::Error(do_harderror,do_exception)>
See L<"Misfeatures"> for details.
+=item C<OS2::DLLname([how [, \&xsub]])>
+
+Gives the information about the Perl DLL or the DLL containing the C
+function bound to by C<&xsub>. The meaning of C<how> is: default (2):
+full name; 0: handle; 1: module name.
+
=back
(Note that some of these may be moved to different libraries -
=item $OS2::emx_rev
-same as _emx_rev of EMX, a string similar to C<0.9c>.
+numeric value is the same as _emx_rev of EMX, a string value the same
+as _emx_vprt (similar to C<0.9c>).
=item $OS2::emx_env
a number C<OS_MAJOR + 0.001 * OS_MINOR>.
+=item $OS2::is_aout
+
+true if the Perl library was compiled in AOUT format.
+
+=item $OS2::can_fork
+
+true if the current executable is an AOUT EMX executable, so Perl can
+fork. Do not use this, use the portable check for
+$Config::Config{dfork}.
+
+=item $OS2::nsyserror
+
+This variable (default is 1) controls whether to enforce the contents
+of $^E to start with C<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 C<SYS0003>-like id prepended, some not.)
+
=back
=head2 Misfeatures
=item *
-Since F<sh.exe> is used for globing (see L<perlfunc/glob>), the bugs
-of F<sh.exe> plague perl as well.
-
-In particular, uppercase letters do not work in C<[...]>-patterns with
-the current pdksh.
+See L<"Text-mode filehandles">.
=item *
To circumvent this, Perl uses two hacks. They help against I<one> type of
damage only: FP flags changed when loading a DLL.
-One of the hacks is to disable floating point exceptions on startup (as
+One of the hacks is to disable floating point exceptions 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.
shutdown will be automatically cancelled. Do not call C<perl_hmq_GET(1)>
unless you are going to process messages on an orderly basis.
+=item * Treating errors reported by OS/2 API
+
+There are two principal conventions (it is useful to call them C<Dos*>
+and C<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 C<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 C<Win*> API report success/fail via the result being
+C<TRUE>/C<FALSE>; to find the reason for the failure one should call
+WinGetLastError() API.
+
+Some C<Win*> entry points also overload a "meaningful" return value
+with the error indicator; having a 0 return value indicates an error.
+Yet some other C<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 WinGetLastError() API to distinguish a successful call from a
+failing one.
+
+By convention, all the calls to OS/2 API should indicate 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 I<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 desirable 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
+
+=over
+
+=item C<CheckOSError(expr)>
+
+Returns true on error, sets $^E. Expects expr() be a call of
+C<Dos*>-style API.
+
+=item C<CheckWinError(expr)>
+
+Returns true on error, sets $^E. Expects expr() be a call of
+C<Win*>-style API.
+
+=item C<SaveWinError(expr)>
+
+Returns C<expr>, sets $^E from WinGetLastError() if C<expr> is false.
+
+=item C<SaveCroakWinError(expr,die,name1,name2)>
+
+Returns C<expr>, sets $^E from WinGetLastError() if C<expr> is false,
+and die()s if C<die> and $^E are true. The message to die is the
+concatenated strings C<name1> and C<name2>, separated by C<": "> from
+the contents of $^E.
+
+=item C<WinError_2_Perl_rc>
+
+Sets C<Perl_rc> to the return value of WinGetLastError().
+
+=item C<FillWinError>
+
+Sets C<Perl_rc> to the return value of WinGetLastError(), and sets $^E
+to the corresponding value.
+
+=item C<FillOSError(rc)>
+
+Sets C<Perl_rc> to C<rc>, and sets $^E to the corresponding value.
+
+=back
+
+=item * 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
+I<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 available on floppy-boot setup.
+
+To make these calls fail I<only when the calls are executed>, 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 available for such linking is provided (see C<entries_ordinals>
+- and also C<PMWIN_entries> - in F<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.
+
=back
=head1 Perl flavors
a VIO window present, but not C<detach>ed (run C<help detach> for more info).
Very useful for extensions which use PM, like C<Perl/Tk> or C<OpenGL>.
+Note also that the differences between PM and VIO executables are only
+in the I<default> behaviour. One can start I<any> executable in
+I<any> kind of session by using the arguments C</fs>, C</pm> or
+C</win> switches of the command C<start> (of F<CMD.EXE> or a similar
+shell). Alternatively, one can use the numeric first argument of the
+C<system> Perl function (see L<C<OS2::Process>>).
+
=head2 F<perl___.exe>
This is an C<omf>-style executable which is dynamically linked to
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:
-all the references to external functions are resolved at the compile time;
-there is no runtime fixup of the DLLs after they are loaded into memory.
+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 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
Here we list major changes which could make you by surprise.
+=head2 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.
+
=head2 Priorities
C<setpriority> and C<getpriority> are not compatible with earlier
whether C<LIBPATHSTRICT> affects this case).
B<REMARK>. Unless newer kernels allow F<.> in C<BEGINLIBPATH> (older
-do not), this mess cannot be completely cleaned.
+do not), this mess cannot be completely cleaned. (It turns out that
+as of the beginning of 2002, F<.> is not allowed, but F<.\.> is - and
+it has the same effect.)
B<REMARK>. C<LIBPATHSTRICT>, C<BEGINLIBPATH> and C<ENDLIBPATH> are
=item C<COND_WAIT>
-may have a race condition. Needs a reimplementation (in terms of chaining
-waiting threads, with the linked list stored in per-thread structure?).
+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
+waiting threads, with the linked list stored in per-thread structure?)?)
=item F<os2.c>
=head1 AUTHOR
-Ilya Zakharevich, ilya@math.ohio-state.edu
+Ilya Zakharevich, cpan@ilyaz.org
=head1 SEE ALSO
projects / p5sagit/p5-mst-13.2.git / commitdiff