OS2::DLL - access to DLLs with REXX calling convention.

- NAME

- NOTE

- SYNOPSIS
- DESCRIPTION

- Create a DLL handle
- Create a DLL handle (looking in some strange locations)
- Loads DLL by name
- Check for functions (optional):
- Create a Perl wrapper (optional):
- Call external function with REXX calling convention:

- Inspecting the module
- Low-level API
- ENVIRONMENT
- AUTHOR

# NAME

OS2::DLL - access to DLLs with REXX calling convention.

## NOTE

When you use this module, the REXX variable pool is not available.

See documentation of the OS2::REXX manpage module if you need the variable pool.

# SYNOPSIS

            use OS2::DLL;
            $emx_dll = OS2::DLL->module('emx');
            $emx_version = $emx_dll->emx_revision();
            $func_emx_version = $emx_dll->wrapper_REXX('#128'); # emx_revision
            $emx_version = $func_emx_version->();

# DESCRIPTION

## Create a DLL handle

            $dll = OS2::DLL->module( NAME [, WHERE] );

Loads an OS/2 module NAME, looking in directories WHERE (adding the extension .dll), if the DLL is not found there, loads in the usual OS/2 way (via LIBPATH and other settings). Croaks with a verbose report on failure.

The DLL is not unloaded when the return value is destroyed.

## Create a DLL handle (looking in some strange locations)

            $dll = OS2::DLL->new( NAME [, WHERE] );

Same as `module`, but in addition to WHERE, looks in environment paths PERL5REXX, PERLREXX, PATH (provided for backward compatibility).

## Loads DLL by name

            $dll = load OS2::DLL NAME [, WHERE];

Same as `new`, but returns DLL object reference, or undef on failure (in this case one can get the reason via `DynaLoader::dl_error()`) (provided for backward compatibility).

## Check for functions (optional):

            BOOL = $dll->find(NAME [, NAME [, ...]]);

Returns true if all functions are available. As a side effect, creates a REXX wrapper with the specified name in the package constructed by the name of the DLL so that the next call to `$dll-`NAME()> will pick up the cached method.

## Create a Perl wrapper (optional):

            $func = $dll->wrapper_REXX(NAME);

Returns a reference to a Perl function wrapper for the entry point NAME in the DLL. Similar to the OS/2 API, the NAME may be `"#123"` - in this case the ordinal is loaded. Croaks with a meaningful error message if NAME does not exists (although the message for the case when the name is an ordinal may be confusing).

## Call external function with REXX calling convention:

            $ret_string = $dll->function_name(arguments);

Returns the return string if the REXX return code is 0, else undef. Dies with error message if the function is not available. On the first call resolves the name in the DLL and caches the Perl wrapper; future calls go through the wrapper.

Unless used inside REXX environment (see the OS2::REXX manpage), the REXX runtime environment (variable pool, queue etc.) is not available to the called function.

# Inspecting the module

$module->handle
$module->fullname

  Return the (integer) handle and full path name of a loaded DLL.

  TODO: the module name (whatever is specified in the `LIBRARY` statement of .def file when linking) via OS2::Proc.

$module->`has_f32($name)`

  Returns the address of a 32-bit entry point with name $name, or 0 if none found. (Keep in mind that some entry points may be 16-bit, and some may have capitalized names comparing to callable-from-C counterparts.) Name of the form `#197` will find entry point with ordinal 197.

libPath_find($name [, $flags])

  Looks for the DLL $name on `BEGINLIBPATH`, `LIBPATH`, `ENDLIBPATH` if bits 0x1, 0x2, 0x4 of $flags are set correspondingly. If called with no arguments, looks on all 3 locations. Returns the full name of the found file. DLL is not loaded.

  $name has .dll appended unless it already has an extension.

# Low-level API

Call a _System linkage function via a pointer

  If a function takes up to 20 ULONGs and returns ULONG:

       $res = call20( $pointer, $arg0, $arg1, ...);

Same for packed arguments:

       $res = call20_p( $pointer, pack 'L20', $arg0, $arg1, ...);

Same for `regparm(3)` function:

       $res = call20_rp3( $pointer, $arg0, $arg1, ...);

Same for packed arguments and `regparm(3)` function

       $res = call20_rp3_p( $pointer, pack 'L20', $arg0, $arg1, ...);

Same for a function which returns non-0 and sets system-error on error

       call20_Dos( $msg, $pointer, $arg0, $arg1, ...); # die("$msg: $^E") if error

  [Good for `Dos*` API - and rare `Win*` calls.]

Same for a function which returns 0 and sets `WinLastError()` on error

       $res = call20_Win( $msg, $pointer, $arg0, $arg1, ...);
       # would die("$msg: $^E") if error

  [Good for most of `Win*` API.]

Same for a function which returns 0 and sets `WinLastError()` on error but 0 is also a valid return

       $res = call20_Win_0OK( $msg, $pointer, $arg0, $arg1, ...);
       # would die("$msg: $^E") if error

  [Good for some of `Win*` API.]

As previous, but without `die()`

       $res = call20_Win_0OK_survive( $pointer, $arg0, $arg1, ...);
       if ($res == 0 and $^E) {       # Do error processing here
       }

  [Good for some of `Win*` API.]

# ENVIRONMENT

If `PERL_REXX_DEBUG` is set, emits debugging output. Looks for DLLs in `PERL5REXX`, `PERLREXX`, `PATH`.

# AUTHOR

Extracted by Ilya Zakharevich perl-module-OS2-DLL@ilyaz.org from the OS2::REXX manpage written by Andreas Kaiser ak@ananke.s.bawue.de.

OS2::DLL - access to DLLs with REXX calling convention.