NAME

       FFI::Platypus::DL - Slightly non-portable interface to libdl

VERSION

       version 2.00

SYNOPSIS

        use FFI::Platypus 2.00;
        use FFI::Platypus::DL;

        my $handle = dlopen("./libfoo.so", RTLD_PLATYPUS_DEFAULT);
        my $address = dlsym($handle, "my_function_named_foo");
        my $ffi = FFI::Platypus->new( api => 2 );
        $ffi->function($address => [] => 'void')->call;
        dlclose($handle);

DESCRIPTION

       This module provides an interface to libdl, the dynamic loader on UNIX.  The underlying
       interface has always been used by FFI::Platypus, but it wasn't a public interface until
       version 0.52.  The name was changed with that version when it became a public interface,
       so be sure to specify that version if you are going to use it.

       It is somewhat non-portable for these reasons:

       GNU extensions
           It provides some GNU extensions to platforms such as Linux that support them.

       Windows
           It provides an emulation layer on Windows.  The emulation layer only supports
           "RTLD_PLATYPUS_DEFAULT" as a flag.  The emulation layer emulates the convention
           described below of passing "undef" as the dynamic library name to mean, use the
           currently running executable.  I've used it without any problems for years, but
           Windows is not my main development platform.

FUNCTIONS

   dlopen
        my $handle = dlopen($filename, $flags);

       This opens a dynamic library in the context of the dynamic loader.  $filename is the full
       or relative path to a dynamic library (usually a ".so" on Linux and some other UNIXen, a
       ".dll" on Windows and a ".dylib" on OS X).  $flags are flags that can be used to alter the
       behavior of the library and the symbols it contains.  The return value is an opaque
       pointer or $handle which can be used to look up symbols with "dlsym".  The handle should
       be closed with "dlclose" when you are done with it.

       By convention if you pass in "undef" for the filename, the currently loaded executable
       will be used instead of a separate dynamic library.  This is the easiest and most portable
       way to find the address of symbols in the standard C library.  This convention is baked
       into most UNIXen, but this capability is emulated in Windows which doesn't come with the
       capability out of the box.

       If there is an error in opening the library then "undef" will be returned and the
       diagnostic for the failure can be retrieved with "dlerror" as described below.

       Not all flags are supported on all platforms.  You can test if a flag is available using
       can:

        if(FFI::Platypus::DL->can('RTLD_LAZY'))
        {
          ...
        }

       Typically where flags are not mutually exclusive, they can be or'd together:

        my $handle = dlopen("libfoo.so", RTLD_LAZY | RTLD_GLOBAL);

       Check your operating system documentation for detailed descriptions of these flags.

       RTLD_PLATYPUS_DEFAULT
           This is the FFI::Platypus default for "dlopen" (NOTE: NOT the libdl default).  This is
           the only flag supported on Windows.  For historical reasons, this is usually
           "RTLD_LAZY" on Unix and 0 on Windows.

       RTLD_LAZY
           Perform lazy binding.

       RTLD_NOW
           Resolve all symbols before returning from "dlopen".  Error if all symbols cannot
           resolve.

       RTLD_GLOBAL
           Symbols are shared.

       RTLD_LOCAL
           Symbols are NOT shared.

       RTLD_NODELETE
           glibc 2.2 extension.

       RTLD_NOLOAD
           glibc 2.2 extension.

       RTLD_DEEPBIND
           glibc 2.3.4 extension.

   dlsym
        my $opaque = dlsym($handle, $symbol);

       This looks up the given $symbol in the library pointed to by $handle.  If the symbol is
       found, the address for that symbol is returned as an opaque pointer.  This pointer can be
       passed into the FFI::Platypus "function" and "attach" methods instead of a function name.

       If the symbol cannot be found then "undef" will be returned and the diagnostic for the
       failure can be retrieved with "dlerror" as described below.

   dlclose
        my $status = dlclose($handle);

       On success, "dlclose" returns 0; on error, it returns a nonzero value, and the diagnostic
       for the failure can be retrieved with "dlerror" as described below.

   dlerror
        my $error_string = dlerror;

       Returns the human readable diagnostic for the reason for the failure for the most recent
       "dl" prefixed function call.

CAVEATS

       Some flags for "dlopen" are not portable.  This module may not be supported platforms
       added to FFI::Platypus in the future.  It does work as far as I know on all of the
       currently supported platforms.

SEE ALSO

       FFI::Platypus

AUTHOR

       Author: Graham Ollis <plicease@cpan.org>

       Contributors:

       Bakkiaraj Murugesan (bakkiaraj)

       Dylan Cali (calid)

       pipcet

       Zaki Mughal (zmughal)

       Fitz Elliott (felliott)

       Vickenty Fesunov (vyf)

       Gregor Herrmann (gregoa)

       Shlomi Fish (shlomif)

       Damyan Ivanov

       Ilya Pavlov (Ilya33)

       Petr Písař (ppisar)

       Mohammad S Anwar (MANWAR)

       Håkon Hægland (hakonhagland, HAKONH)

       Meredith (merrilymeredith, MHOWARD)

       Diab Jerius (DJERIUS)

       Eric Brine (IKEGAMI)

       szTheory

       José Joaquín Atria (JJATRIA)

       Pete Houston (openstrike, HOUSTON)

COPYRIGHT AND LICENSE

       This software is copyright (c) 2015-2022 by Graham Ollis.

       This is free software; you can redistribute it and/or modify it under the same terms as
       the Perl 5 programming language system itself.