perlos2.pod

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in subdirectories may be buggy, and would not run as "child" scripts.  The
interdependency of modules can strike you; however, since non-XS modules
are already installed, the prerequisites of most modules have a very good
chance to be present.

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

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

  emxaout foo.lib
  emximp -o foo.a foo.lib

whichever is appropriate.)  Also, make sure that the DLLs for external
libraries are usable with with executables compiled without C<-Zmtd> options.

When you are sure that only a few subdirectories
lead to failures, you may want to add C<-j4> option to C<make> to speed up
skipping subdirectories with already finished build.

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

  make install |& tee 00aout_i

Now you can rename the file F<./perl.exe> generated during the last phase
to F<perl_5.8.2.exe>; place it on C<PATH>; if there is an inter-dependency
between some XS modules, you may need to repeat the C<test>/C<install> loop
with this new executable and some excluded modules - until the procedure
converges.

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

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

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

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

=item 8.

Make sure that the installed modules are actually installed in the location
of the new Perl, and are not inherited from entries of @INC given for
inheritance from the older versions of Perl: set C<PERLLIB_582_PREFIX> to
redirect the new version of Perl to a new location, and copy the installed
files to this new location.  Redo the tests to make sure that the versions of
modules inherited from older versions of Perl are not needed.

Actually, the log output of L<pod2ipf> during the step 6 gives a very detailed
info about which modules are loaded from which place; so you may use it as
an additional verification tool.

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

  pfind . -f "!(/\.(pm|pl|ix|al|h|a|lib|txt|pod|imp|bs|dll|ld|bs|inc|xbm|yml|cgi|uu|e2x|skip|packlist|eg|cfg|html|pub|enc|all|ini|po|pot)$/i or /^\w+$/") | less

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

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

=item 9.

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

Include F<perl5.def> so that people can relink the perl DLL preserving
the binary compatibility, or can create compatibility DLLs.  Include the diff
files (C<diff -pu old new>) of fixes you did so that people can rebuild your
version.  Include F<perl5.map> so that one can use remote debugging.

=item 10.

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

=item 11.

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

=back

=head1 Building custom F<.EXE> files

The Perl executables can be easily rebuilt at any moment.  Moreover, one can
use the I<embedding> interface (see L<perlembed>) to make very customized
executables.

=head2 Making executables with a custom collection of statically loaded extensions

It is a little bit easier to do so while I<decreasing> the list of statically
loaded extensions.  We discuss this case only here.

=over

=item 1.

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

  use ExtUtils::MakeMaker;
  WriteMakefile NAME => 'dummy';

=item 2.

Run it with the flavor of Perl (F<perl.exe> or F<perl_.exe>) you want to
rebuild.

  perl_ Makefile.PL

=item 3.

Ask it to create new Perl executable:

  make perl

(you may need to manually add C<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 executable; check with

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

).

=item 4.

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

  make perl

will produce a customized executable.

=back

=head2 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 relatively 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 I<embedding> interface (see L<perlembed>), such
things are easy to do repeating the steps outlined in L<Making
executables with a custom collection of statically loaded extensions>, and
doing more comprehensive edits to main() of F<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

=over

=item 1.

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

=item 2.

Prepends the above directory to C<BEGINLIBPATH>;

=item 3.

Fails if the Perl DLL found via C<BEGINLIBPATH> is different from what was
loaded on step 1; e.g., another process could have loaded it from C<LIBPATH>
or from a different value of C<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 C<BEGINLIBPATH> with C<LIBPATHSTRICT=T> (available
with kernels after September 2000).

=item 4.

Loads Perl library from C<$exedir/../dll/lib/>.

=item 5.

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

=back

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 applications, 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 <os2.h>

  #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);
  }


=head1 Build FAQ

=head2 Some C</> became C<\> in pdksh.

You have a very old pdksh. See L<Prerequisites>.

=head2 C<'errno'> - unresolved external

You do not have MT-safe F<db.lib>. See L<Prerequisites>.

=head2 Problems with tr or sed

reported with very old version of tr and sed.

=head2 Some problem (forget which ;-)

You have an older version of F<perl.dll> on your LIBPATH, which
broke the build of extensions.

=head2 Library ... not found

You did not run C<omflibs>. See L<Prerequisites>.

=head2 Segfault in make

You use an old version of GNU make. See L<Prerequisites>.

=head2 op/sprintf test failure

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

=head1 Specific (mis)features of OS/2 port

=head2 C<setpriority>, C<getpriority>

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

B<WARNING>.  Calling C<getpriority> on a non-existing process could lock
the system before Warp3 fixpak22.  Starting with Warp3, Perl will use
a workaround: it aborts getpriority() if the process is not present.
This is not possible on older versions C<2.*>, and has a race
condition anyway.

=head2 C<system()>

Multi-argument form of C<system()> allows an additional numeric
argument. The meaning of this argument is described in
L<OS2::Process>.

When finding a program to run, Perl first asks the OS to look for executables
on C<PATH> (OS/2 adds extension F<.exe> if no extension is present).
If not found, it looks for a script with possible extensions 
added in this order: no extension, F<.cmd>, F<.btm>, 
F<.bat>, F<.pl>.  If found, Perl checks the start of the file for magic
strings C<"#!"> and C<"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., C<system 'foo', 'bar', 'baz'> may lead Perl to finding
F<C:/emx/bin/foo.cmd> with the first line being

 extproc /bin/bash    -x   -c

If F</bin/bash.exe> is not found, then Perl looks for an executable F<bash.exe> on
C<PATH>.  If found in F<C:/emx.add/bin/bash.exe>, then the above system() is
translated 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 F</bin/sh> Perl uses
the hardwired-or-customized shell (see C<L<"PERL_SH_DIR">>).

The above search for "interpreter" is recursive: if F<bash> executable is not
found, but F<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 C<OS2::Process> to disable this magic.

B<WARNING>.  Due to the described logic, you need to explicitly
specify F<.com> extension if needed.  Moreover, if the executable
F<perl5.6.1> is requested, Perl will not look for F<perl5.6.1.exe>.
[This may change in the future.]