1FFI::Platypus(3) User Contributed Perl Documentation FFI::Platypus(3)
2
6 FFI::Platypus - Write Perl bindings to non-Perl libraries with FFI. No
7 XS required.
8
10 version 1.43
11
13 use FFI::Platypus 1.00;
14 # for all new code you should use api => 1
16 my $ffi = FFI::Platypus->new( api => 1 );
17 $ffi->lib(undef); # search libc
18 # call dynamically
20 $ffi->function( puts => ['string'] => 'int' )->call("hello world");
21 # attach as a xsub and call (much faster)
23 $ffi->attach( puts => ['string'] => 'int' );
24 puts("hello world");
25
27 Platypus is a library for creating interfaces to machine code libraries
28 written in languages like C, C++, Go, Fortran, Rust, Pascal.
29 Essentially anything that gets compiled into machine code. This
30 implementation uses "libffi" to accomplish this task. "libffi" is
31 battle tested by a number of other scripting and virtual machine
32 languages, such as Python and Ruby to serve a similar role. There are
33 a number of reasons why you might want to write an extension with
34 Platypus instead of XS:
35 FFI / Platypus does not require messing with the guts of Perl
37 XS is less of an API and more of the guts of perl splayed out to do
38 whatever you want. That may at times be very powerful, but it can
39 also be a frustrating exercise in hair pulling.
40 FFI / Platypus is portable
42 Lots of languages have FFI interfaces, and it is subjectively
43 easier to port an extension written in FFI in Perl or another
44 language to FFI in another language or Perl. One goal of the
45 Platypus Project is to reduce common interface specifications to a
46 common format like JSON that could be shared between different
47 languages.
48 FFI / Platypus could be a bridge to Perl 6
50 One of those "other" languages could be Perl 6 and Perl 6 already
51 has an FFI interface I am told.
52 FFI / Platypus can be reimplemented
54 In a bright future with multiple implementations of Perl 5, each
55 interpreter will have its own implementation of Platypus, allowing
56 extensions to be written once and used on multiple platforms, in
57 much the same way that Ruby-FFI extensions can be use in Ruby,
58 JRuby and Rubinius.
59 FFI / Platypus is pure perl (sorta)
61 One Platypus script or module works on any platform where the
62 libraries it uses are available. That means you can deploy your
63 Platypus script in a shared filesystem where they may be run on
64 different platforms. It also means that Platypus modules do not
65 need to be installed in the platform specific Perl library path.
66 FFI / Platypus is not C or C++ centric
68 XS is implemented primarily as a bunch of C macros, which requires
69 at least some understanding of C, the C pre-processor, and some C++
70 caveats (since on some platforms Perl is compiled and linked with a
71 C++ compiler). Platypus on the other hand could be used to call
72 other compiled languages, like Fortran, Go, Rust, Pascal, C++, or
73 even assembly, allowing you to focus on your strengths.
74 FFI / Platypus does not require a parser
76 Inline isolates the extension developer from XS to some extent, but
77 it also requires a parser. The various Inline language bindings
78 are a great technical achievement, but I think writing a parser for
79 every language that you want to interface with is a bit of an anti-
80 pattern.
81 This document consists of an API reference, a set of examples, some
83 support and development (for contributors) information. If you are new
84 to Platypus or FFI, you may want to skip down to the EXAMPLES to get a
85 taste of what you can do with Platypus.
86 Platypus has extensive documentation of types at FFI::Platypus::Type
88 and its custom types API at FFI::Platypus::API.
89 You are strongly encouraged to use API level 1 for all new code. There
91 are a number of improvements and design fixes that you get for free.
92 You should even consider updating existing modules to use API level 1
93 where feasible. How do I do that you might ask? Simply pass in the
94 API level to the platypus constructor.
95 my $ffi = FFI::Platypus->new( api => 1 );
97 The Platypus documentation has already been updated to assume API level
99 1.
100
102 new
103 my $ffi = FFI::Platypus->new( api => 1, %options);
104 Create a new instance of FFI::Platypus.
106 Any types defined with this instance will be valid for this instance
108 only, so you do not need to worry about stepping on the toes of other
109 CPAN FFI / Platypus Authors.
110 Any functions found will be out of the list of libraries specified with
112 the lib attribute.
113 options
115 api Sets the API level. Legal values are
117 0 Original API level. See FFI::Platypus::TypeParser::Version0
119 for details on the differences.
120 1 Enable the next generation type parser which allows pass-by-
122 value records and type decoration on basic types. Using API
123 level 1 prior to Platypus version 1.00 will trigger a (noisy)
124 warning.
125 All new code should be written with this set to 1! The
127 Platypus documentation assumes this api level is set.
128 lib Either a pathname (string) or a list of pathnames (array ref of
130 strings) to pre-populate the lib attribute. Use "[undef]" to
131 search the current process for symbols.
132 0.48
134 "undef" (without the array reference) can be used to search the
136 current process for symbols.
137 ignore_not_found
139 [version 0.15]
140 Set the ignore_not_found attribute.
142 lang
144 [version 0.18]
145 Set the lang attribute.
147
149 lib
150 $ffi->lib($path1, $path2, ...);
151 my @paths = $ffi->lib;
152 The list of libraries to search for symbols in.
154 The most portable and reliable way to find dynamic libraries is by
156 using FFI::CheckLib, like this:
157 use FFI::CheckLib 0.06;
159 $ffi->lib(find_lib_or_die lib => 'archive');
160 # finds libarchive.so on Linux
161 # libarchive.bundle on OS X
162 # libarchive.dll (or archive.dll) on Windows
163 # cygarchive-13.dll on Cygwin
164 # ...
165 # and will die if it isn't found
166 FFI::CheckLib has a number of options, such as checking for specific
168 symbols, etc. You should consult the documentation for that module.
169 As a special case, if you add "undef" as a "library" to be searched,
171 Platypus will also search the current process for symbols. This is
172 mostly useful for finding functions in the standard C library, without
173 having to know the name of the standard c library for your platform (as
174 it turns out it is different just about everywhere!).
175 You may also use the "find_lib" method as a shortcut:
177 $ffi->find_lib( lib => 'archive' );
179 ignore_not_found
181 [version 0.15]
182 $ffi->ignore_not_found(1);
184 my $ignore_not_found = $ffi->ignore_not_found;
185 Normally the attach and function methods will throw an exception if it
187 cannot find the name of the function you provide it. This will change
188 the behavior such that function will return "undef" when the function
189 is not found and attach will ignore functions that are not found. This
190 is useful when you are writing bindings to a library and have many
191 optional functions and you do not wish to wrap every call to function
192 or attach in an "eval".
193 lang
195 [version 0.18]
196 $ffi->lang($language);
198 Specifies the foreign language that you will be interfacing with. The
200 default is C. The foreign language specified with this attribute
201 changes the default native types (for example, if you specify Rust, you
202 will get "i32" as an alias for "sint32" instead of "int" as you do with
203 C).
204 If the foreign language plugin supports it, this will also enable
206 Platypus to find symbols using the demangled names (for example, if you
207 specify CPP for C++ you can use method names like "Foo::get_bar()" with
208 "attach" or "function".
209 api
211 [version 1.11]
212 my $level = $ffi->api;
214 Returns the API level of the Platypus instance.
216
218 type
219 $ffi->type($typename);
220 $ffi->type($typename => $alias);
221 Define a type. The first argument is the native or C name of the type.
223 The second argument (optional) is an alias name that you can use to
224 refer to this new type. See FFI::Platypus::Type for legal type
225 definitions.
226 Examples:
228 $ffi->type('sint32'); # only checks to see that sint32 is a valid type
230 $ffi->type('sint32' => 'myint'); # creates an alias myint for sint32
231 $ffi->type('bogus'); # dies with appropriate diagnostic
232 custom_type
234 $ffi->custom_type($alias => {
235 native_type => $native_type,
236 native_to_perl => $coderef,
237 perl_to_native => $coderef,
238 perl_to_native_post => $coderef,
239 });
240 Define a custom type. See FFI::Platypus::Type#Custom-Types for
242 details.
243 load_custom_type
245 $ffi->load_custom_type($name => $alias, @type_args);
246 Load the custom type defined in the module $name, and make an alias
248 $alias. If the custom type requires any arguments, they may be passed
249 in as @type_args. See FFI::Platypus::Type#Custom-Types for details.
250 If $name contains "::" then it will be assumed to be a fully qualified
252 package name. If not, then "FFI::Platypus::Type::" will be prepended to
253 it.
254 types
256 my @types = $ffi->types;
257 my @types = FFI::Platypus->types;
258 Returns the list of types that FFI knows about. This will include the
260 native "libffi" types (example: "sint32", "opaque" and "double") and
261 the normal C types (example: "unsigned int", "uint32_t"), any types
262 that you have defined using the type method, and custom types.
263 The list of types that Platypus knows about varies somewhat from
265 platform to platform, FFI::Platypus::Type includes a list of the core
266 types that you can always count on having access to.
267 It can also be called as a class method, in which case, no user defined
269 or custom types will be included in the list.
270 type_meta
272 my $meta = $ffi->type_meta($type_name);
273 my $meta = FFI::Platypus->type_meta($type_name);
274 Returns a hash reference with the meta information for the given type.
276 It can also be called as a class method, in which case, you won't be
278 able to get meta data on user defined types.
279 The format of the meta data is implementation dependent and subject to
281 change. It may be useful for display or debugging.
282 Examples:
284 my $meta = $ffi->type_meta('int'); # standard int type
286 my $meta = $ffi->type_meta('int[64]'); # array of 64 ints
287 $ffi->type('int[128]' => 'myintarray');
288 my $meta = $ffi->type_meta('myintarray'); # array of 128 ints
289 mangler
291 $ffi->mangler(\&mangler);
292 Specify a customer mangler to be used for symbol lookup. This is
294 usually useful when you are writing bindings for a library where all of
295 the functions have the same prefix. Example:
296 $ffi->mangler(sub {
298 my($symbol) = @_;
299 return "foo_$symbol";
300 });
301 $ffi->function( get_bar => [] => 'int' ); # attaches foo_get_bar
303 my $f = $ffi->function( set_baz => ['int'] => 'void' );
305 $f->call(22); # calls foo_set_baz
306 function
308 my $function = $ffi->function($name => \@argument_types => $return_type);
309 my $function = $ffi->function($address => \@argument_types => $return_type);
310 my $function = $ffi->function($name => \@argument_types => $return_type, \&wrapper);
311 my $function = $ffi->function($address => \@argument_types => $return_type, \&wrapper);
312 Returns an object that is similar to a code reference in that it can be
314 called like one.
315 Caveat: many situations require a real code reference, so at the price
317 of a performance penalty you can get one like this:
318 my $function = $ffi->function(...);
320 my $coderef = sub { $function->(@_) };
321 It may be better, and faster to create a real Perl function using the
323 attach method.
324 In addition to looking up a function by name you can provide the
326 address of the symbol yourself:
327 my $address = $ffi->find_symbol('my_function');
329 my $function = $ffi->function($address => ...);
330 Under the covers, function uses find_symbol when you provide it with a
332 name, but it is useful to keep this in mind as there are alternative
333 ways of obtaining a functions address. Example: a C function could
334 return the address of another C function that you might want to call,
335 or modules such as FFI::TinyCC produce machine code at runtime that you
336 can call from Platypus.
337 [version 0.76]
339 If the last argument is a code reference, then it will be used as a
341 wrapper around the function when called. The first argument to the
342 wrapper will be the inner function, or if it is later attached an xsub.
343 This can be used if you need to verify/modify input/output data.
344 Examples:
346 my $function = $ffi->function('my_function_name', ['int', 'string'] => 'string');
348 my $return_string = $function->(1, "hi there");
349 [version 0.91]
351 my $function = $ffi->function( $name => \@fixed_argument_types => \@var_argument_types => $return_type);
353 my $function = $ffi->function( $name => \@fixed_argument_types => \@var_argument_types => $return_type, \&wrapper);
354 my $function = $ffi->function( $name => \@fixed_argument_types => \@var_argument_types);
355 my $function = $ffi->function( $name => \@fixed_argument_types => \@var_argument_types => \&wrapper);
356 Version 0.91 and later allows you to creat functions for c variadic
358 functions (such as printf, scanf, etc) which can take a variable number
359 of arguments. The first set of arguments are the fixed set, the second
360 set are the variable arguments to bind with. The variable argument
361 types must be specified in order to create a function object, so if you
362 need to call variadic function with different set of arguments then you
363 will need to create a new function object each time:
364 # int printf(const char *fmt, ...);
366 $ffi->function( printf => ['string'] => ['int'] => 'int' )
367 ->call("print integer %d\n", 42);
368 $ffi->function( printf => ['string'] => ['string'] => 'int' )
369 ->call("print string %s\n", 'platypus');
370 Some older versions of libffi and possibly some platforms may not
372 support variadic functions. If you try to create a one, then an
373 exception will be thrown.
374 [version 1.26]
376 If the return type is omitted then "void" will be the assumed return
378 type.
379 attach
381 $ffi->attach($name => \@argument_types => $return_type);
382 $ffi->attach([$c_name => $perl_name] => \@argument_types => $return_type);
383 $ffi->attach([$address => $perl_name] => \@argument_types => $return_type);
384 $ffi->attach($name => \@argument_types => $return_type, \&wrapper);
385 $ffi->attach([$c_name => $perl_name] => \@argument_types => $return_type, \&wrapper);
386 $ffi->attach([$address => $perl_name] => \@argument_types => $return_type, \&wrapper);
387 Find and attach a C function as a real live Perl xsub. The advantage
389 of attaching a function over using the function method is that it is
390 much much much faster since no object resolution needs to be done. The
391 disadvantage is that it locks the function and the FFI::Platypus
392 instance into memory permanently, since there is no way to deallocate
393 an xsub.
394 If just one $name is given, then the function will be attached in Perl
396 with the same name as it has in C. The second form allows you to give
397 the Perl function a different name. You can also provide an address
398 (the third form), just like with the function method.
399 Examples:
401 $ffi->attach('my_function_name', ['int', 'string'] => 'string');
403 $ffi->attach(['my_c_function_name' => 'my_perl_function_name'], ['int', 'string'] => 'string');
404 my $string1 = my_function_name($int);
405 my $string2 = my_perl_function_name($int);
406 [version 0.20]
408 If the last argument is a code reference, then it will be used as a
410 wrapper around the attached xsub. The first argument to the wrapper
411 will be the inner xsub. This can be used if you need to verify/modify
412 input/output data.
413 Examples:
415 $ffi->attach('my_function', ['int', 'string'] => 'string', sub {
417 my($my_function_xsub, $integer, $string) = @_;
418 $integer++;
419 $string .= " and another thing";
420 my $return_string = $my_function_xsub->($integer, $string);
421 $return_string =~ s/Belgium//; # HHGG remove profanity
422 $return_string;
423 });
424 [version 0.91]
426 $ffi->attach($name => \@fixed_argument_types => \@var_argument_types, $return_type);
428 $ffi->attach($name => \@fixed_argument_types => \@var_argument_types, $return_type, \&wrapper);
429 As of version 0.91 you can attach a variadic functions, if it is
431 supported by the platform / libffi that you are using. For details see
432 the "function" documentation. If not supported by the implementation
433 then an exception will be thrown.
434 closure
436 my $closure = $ffi->closure($coderef);
437 my $closure = FFI::Platypus->closure($coderef);
438 Prepares a code reference so that it can be used as a FFI closure (a
440 Perl subroutine that can be called from C code). For details on
441 closures, see FFI::Platypus::Type#Closures and FFI::Platypus::Closure.
442 cast
444 my $converted_value = $ffi->cast($original_type, $converted_type, $original_value);
445 The "cast" function converts an existing $original_value of type
447 $original_type into one of type $converted_type. Not all types are
448 supported, so care must be taken. For example, to get the address of a
449 string, you can do this:
450 my $address = $ffi->cast('string' => 'opaque', $string_value);
452 Something that won't work is trying to cast an array to anything:
454 my $address = $ffi->cast('int[10]' => 'opaque', \@list); # WRONG
456 attach_cast
458 $ffi->attach_cast("cast_name", $original_type, $converted_type);
459 $ffi->attach_cast("cast_name", $original_type, $converted_type, \&wrapper);
460 my $converted_value = cast_name($original_value);
461 This function attaches a cast as a permanent xsub. This will make it
463 faster and may be useful if you are calling a particular cast a lot.
464 [version 1.26]
466 A wrapper may be added as the last argument to "attach_cast" and works
468 just like the wrapper for "attach" and "function" methods.
469 sizeof
471 my $size = $ffi->sizeof($type);
472 my $size = FFI::Platypus->sizeof($type);
473 Returns the total size of the given type in bytes. For example to get
475 the size of an integer:
476 my $intsize = $ffi->sizeof('int'); # usually 4
478 my $longsize = $ffi->sizeof('long'); # usually 4 or 8 depending on platform
479 You can also get the size of arrays
481 my $intarraysize = $ffi->sizeof('int[64]'); # usually 4*64
483 my $intarraysize = $ffi->sizeof('long[64]'); # usually 4*64 or 8*64
484 # depending on platform
485 Keep in mind that "pointer" types will always be the pointer / word
487 size for the platform that you are using. This includes strings,
488 opaque and pointers to other types.
489 This function is not very fast, so you might want to save this value as
491 a constant, particularly if you need the size in a loop with many
492 iterations.
493 alignof
495 [version 0.21]
496 my $align = $ffi->alignof($type);
498 Returns the alignment of the given type in bytes.
500 kindof
502 [version 1.24]
503 my $kind = $ffi->kindof($type);
505 Returns the kind of a type. This is a string with a value of one of
507 "void"
509 "scalar"
510 "string"
511 "closure"
512 "record"
513 "record-value"
514 "pointer"
515 "array"
516 "object"
517 countof
519 [version 1.24]
520 my $count = $ffi->countof($type);
522 For array types returns the number of elements in the array (returns 0
524 for variable length array). For the "void" type returns 0. Returns 1
525 for all other types.
526 def
528 [version 1.24]
529 $ffi->def($package, $type, $value);
531 my $value = $ff->def($package, $type);
532 This method allows you to store data for types. If the $package is not
534 provided, then the caller's package will be used. $type must be a
535 legal Platypus type for the FFI::Platypus instance.
536 unitof
538 [version 1.24]
539 my $unittype = $ffi->unitof($type);
541 For array and pointer types, returns the basic type without the array
543 or pointer part. In other words, for "sin16[]" or "sint16*" it will
544 return "sint16".
545 find_lib
547 [version 0.20]
548 $ffi->find_lib( lib => $libname );
550 This is just a shortcut for calling FFI::CheckLib#find_lib and updating
552 the "lib" attribute appropriately. Care should be taken though, as
553 this method simply passes its arguments to FFI::CheckLib#find_lib, so
554 if your module or script is depending on a specific feature in
555 FFI::CheckLib then make sure that you update your prerequisites
556 appropriately.
557 find_symbol
559 my $address = $ffi->find_symbol($name);
560 Return the address of the given symbol (usually function).
562 bundle
564 [version 0.96 api = 1+]
565 $ffi->bundle($package, \@args);
567 $ffi->bundle(\@args);
568 $ffi->bundle($package);
569 $ffi->bundle;
570 This is an interface for bundling compiled code with your distribution
572 intended to eventually replace the "package" method documented above.
573 See FFI::Platypus::Bundle for details on how this works.
574 package
576 [version 0.15 api = 0]
577 $ffi->package($package, $file); # usually __PACKAGE__ and __FILE__ can be used
579 $ffi->package; # autodetect
580 Note: This method is officially discouraged in favor of "bundle"
582 described above.
583 If you use FFI::Build (or the older deprecated Module::Build::FFI to
585 bundle C code with your distribution, you can use this method to tell
586 the FFI::Platypus instance to look for symbols that came with the
587 dynamic library that was built when your distribution was installed.
588 abis
590 my $href = $ffi->abis;
591 my $href = FFI::Platypus->abis;
592 Get the legal ABIs supported by your platform and underlying
594 implementation. What is supported can vary a lot by CPU and by
595 platform, or even between 32 and 64 bit on the same CPU and platform.
596 They keys are the "ABI" names, also known as "calling conventions".
597 The values are integers used internally by the implementation to
598 represent those ABIs.
599 abi
601 $ffi->abi($name);
602 Set the ABI or calling convention for use in subsequent calls to
604 "function" or "attach". May be either a string name or integer value
605 from the "abis" method above.
606
608 Here are some examples. These examples are provided in full with the
609 Platypus distribution in the "examples" directory. There are also some
610 more examples in FFI::Platypus::Type that are related to types.
611 Integer conversions
613 use FFI::Platypus 1.00;
614 my $ffi = FFI::Platypus->new( api => 1 );
616 $ffi->lib(undef);
617 $ffi->attach(puts => ['string'] => 'int');
619 $ffi->attach(atoi => ['string'] => 'int');
620 puts(atoi('56'));
622 Discussion: "puts" and "atoi" should be part of the standard C library
624 on all platforms. "puts" prints a string to standard output, and
625 "atoi" converts a string to integer. Specifying "undef" as a library
626 tells Platypus to search the current process for symbols, which
627 includes the standard c library.
628 libnotify
630 use FFI::CheckLib;
631 use FFI::Platypus 1.00;
632 # NOTE: I ported this from anoter Perl FFI library and it seems to work most
634 # of the time, but also seems to SIGSEGV sometimes. I saw the same behavior
635 # in the old version, and am not really familiar with the libnotify API to
636 # say what is the cause. Patches welcome to fix it.
637 my $ffi = FFI::Platypus->new( api => 1 );
639 $ffi->lib(find_lib_or_exit lib => 'notify');
640 $ffi->attach(notify_init => ['string'] => 'void');
642 $ffi->attach(notify_uninit => [] => 'void');
643 $ffi->attach([notify_notification_new => 'notify_new'] => ['string', 'string', 'string'] => 'opaque');
644 $ffi->attach([notify_notification_update => 'notify_update'] => ['opaque', 'string', 'string', 'string'] => 'void');
645 $ffi->attach([notify_notification_show => 'notify_show'] => ['opaque', 'opaque'] => 'void');
646 notify_init('FFI::Platypus');
648 my $n = notify_new('','','');
649 notify_update($n, 'FFI::Platypus', 'It works!!!', 'media-playback-start');
650 notify_show($n, undef);
651 notify_uninit();
652 Discussion: libnotify is a desktop GUI notification library for the
654 GNOME Desktop environment. This script sends a notification event that
655 should show up as a balloon, for me it did so in the upper right hand
656 corner of my screen.
657 The most portable way to find the correct name and location of a
659 dynamic library is via the FFI::CheckLib#find_lib family of functions.
660 If you are putting together a CPAN distribution, you should also
661 consider using FFI::CheckLib#check_lib_or_exit function in your
662 "Build.PL" or "Makefile.PL" file (If you are using Dist::Zilla, check
663 out the Dist::Zilla::Plugin::FFI::CheckLib plugin). This will provide a
664 user friendly diagnostic letting the user know that the required
665 library is missing, and reduce the number of bogus CPAN testers results
666 that you will get.
667 Also in this example, we rename some of the functions when they are
669 placed into Perl space to save typing:
670 $ffi->attach( [notify_notification_new => 'notify_new']
672 => ['string','string','string']
673 => 'opaque'
674 );
675 When you specify a list reference as the "name" of the function the
677 first element is the symbol name as understood by the dynamic library.
678 The second element is the name as it will be placed in Perl space.
679 Later, when we call "notify_new":
681 my $n = notify_new('','','');
683 We are really calling the C function "notify_notification_new".
685 Allocating and freeing memory
687 use FFI::Platypus 1.00;
688 use FFI::Platypus::Memory qw( malloc free memcpy );
689 my $ffi = FFI::Platypus->new( api => 1 );
691 my $buffer = malloc 12;
692 memcpy $buffer, $ffi->cast('string' => 'opaque', "hello there"), length "hello there\0";
694 print $ffi->cast('opaque' => 'string', $buffer), "\n";
696 free $buffer;
698 Discussion: "malloc" and "free" are standard memory allocation
700 functions available from the standard c library and. Interfaces to
701 these and other memory related functions are provided by the
702 FFI::Platypus::Memory module.
703 structured data records
705 use FFI::Platypus 1.00;
706 use FFI::C;
707 my $ffi = FFI::Platypus->new(
709 api => 1,
710 lib => [undef],
711 );
712 FFI::C->ffi($ffi);
713 package Unix::TimeStruct {
715 FFI::C->struct(tm => [
717 tm_sec => 'int',
718 tm_min => 'int',
719 tm_hour => 'int',
720 tm_mday => 'int',
721 tm_mon => 'int',
722 tm_year => 'int',
723 tm_wday => 'int',
724 tm_yday => 'int',
725 tm_isdst => 'int',
726 tm_gmtoff => 'long',
727 _tm_zone => 'opaque',
728 ]);
729 # For now 'string' is unsupported by FFI::C, but we
731 # can cast the time zone from an opaque pointer to
732 # string.
733 sub tm_zone {
734 my $self = shift;
735 $ffi->cast('opaque', 'string', $self->_tm_zone);
736 }
737 # attach the C localtime function
739 $ffi->attach( localtime => ['time_t*'] => 'tm', sub {
740 my($inner, $class, $time) = @_;
741 $time = time unless defined $time;
742 $inner->(\$time);
743 });
744 }
745 # now we can actually use our My::UnixTime class
747 my $time = Unix::TimeStruct->localtime;
748 printf "time is %d:%d:%d %s\n",
749 $time->tm_hour,
750 $time->tm_min,
751 $time->tm_sec,
752 $time->tm_zone;
753 Discussion: C and other machine code languages frequently provide
755 interfaces that include structured data records (known as "structs" in
756 C). They sometimes provide an API in which you are expected to
757 manipulate these records before and/or after passing them along to C
758 functions. For C pointers to structs, unions and arrays of structs and
759 unions, the easiest interface to use is via FFI::C. If you are working
760 with structs that must be passed as values (not pointers), then you
761 want to use the FFI::Platypus::Record class instead. We will discuss
762 this class later.
763 The C "localtime" function takes a pointer to a C struct. We simply
765 define the members of the struct using the FFI::C "struct" method.
766 Because we used the "ffi" method to tell FFI::C to use our local
767 instance of FFI::Platypus it registers the "tm" type for us, and we can
768 just start using it as a return type!
769 structured data records by-value
771 libuuid
772 use FFI::CheckLib;
773 use FFI::Platypus 1.00;
774 use FFI::Platypus::Memory qw( malloc free );
775 my $ffi = FFI::Platypus->new( api => 1 );
777 $ffi->lib(find_lib_or_exit lib => 'uuid');
778 $ffi->type('string(37)*' => 'uuid_string');
779 $ffi->type('record(16)*' => 'uuid_t');
780 $ffi->attach(uuid_generate => ['uuid_t'] => 'void');
782 $ffi->attach(uuid_unparse => ['uuid_t','uuid_string'] => 'void');
783 my $uuid = "\0" x $ffi->sizeof('uuid_t');
785 uuid_generate($uuid);
786 my $string = "\0" x $ffi->sizeof('uuid_string');
788 uuid_unparse($uuid, $string);
789 print "$string\n";
791 Discussion: libuuid is a library used to generate unique identifiers
793 (UUID) for objects that may be accessible beyond the local system. The
794 library is or was part of the Linux e2fsprogs package.
795 Knowing the size of objects is sometimes important. In this example,
797 we use the sizeof function to get the size of 16 characters (in this
798 case it is simply 16 bytes). We also know that the strings "deparsed"
799 by "uuid_unparse" are exactly 37 bytes.
800 puts and getpid
802 use FFI::Platypus 1.00;
803 my $ffi = FFI::Platypus->new( api => 1 );
805 $ffi->lib(undef);
806 $ffi->attach(puts => ['string'] => 'int');
808 $ffi->attach(getpid => [] => 'int');
809 puts(getpid());
811 Discussion: "puts" is part of standard C library on all platforms.
813 "getpid" is available on Unix type platforms.
814 Math library
816 use FFI::Platypus 1.00;
817 use FFI::CheckLib;
818 my $ffi = FFI::Platypus->new( api => 1 );
820 $ffi->lib(undef);
821 $ffi->attach(puts => ['string'] => 'int');
822 $ffi->attach(fdim => ['double','double'] => 'double');
823 puts(fdim(7.0, 2.0));
825 $ffi->attach(cos => ['double'] => 'double');
827 puts(cos(2.0));
829 $ffi->attach(fmax => ['double', 'double'] => 'double');
831 puts(fmax(2.0,3.0));
833 Discussion: On UNIX the standard c library math functions are
835 frequently provided in a separate library "libm", so you could search
836 for those symbols in "libm.so", but that won't work on non-UNIX
837 platforms like Microsoft Windows. Fortunately Perl uses the math
838 library so these symbols are already in the current process so you can
839 use "undef" as the library to find them.
840 Strings
842 use FFI::Platypus 1.00;
843 my $ffi = FFI::Platypus->new( api => 1 );
845 $ffi->lib(undef);
846 $ffi->attach(puts => ['string'] => 'int');
847 $ffi->attach(strlen => ['string'] => 'int');
848 puts(strlen('somestring'));
850 $ffi->attach(strstr => ['string','string'] => 'string');
852 puts(strstr('somestring', 'string'));
854 #attach puts => [string] => int;
856 puts(puts("lol"));
858 $ffi->attach(strerror => ['int'] => 'string');
860 puts(strerror(2));
862 Discussion: ASCII and UTF-8 Strings are not a native type to "libffi"
864 but the are handled seamlessly by Platypus. If you need to talk to an
865 API that uses so called "wide" strings (APIs which use "const wchar_t*"
866 or "wchar_t*"), then you will want to use the wide string type plugin
867 FFI::Platypus::Type::WideString. APIs which use other arbitrary
868 encodings can be accessed by converting your Perl strings manually with
869 the Encode module.
870 Attach function from pointer
872 use FFI::TinyCC;
873 use FFI::Platypus 1.00;
874 my $ffi = FFI::Platypus->new( api => 1 );
876 my $tcc = FFI::TinyCC->new;
877 $tcc->compile_string(q{
879 int
880 add(int a, int b)
881 {
882 return a+b;
883 }
884 });
885 my $address = $tcc->get_symbol('add');
887 $ffi->attach( [ $address => 'add' ] => ['int','int'] => 'int' );
889 print add(1,2), "\n";
891 Discussion: Sometimes you will have a pointer to a function from a
893 source other than Platypus that you want to call. You can use that
894 address instead of a function name for either of the function or attach
895 methods. In this example we use FFI::TinyCC to compile a short piece
896 of C code and to give us the address of one of its functions, which we
897 then use to create a perl xsub to call it.
898 FFI::TinyCC embeds the Tiny C Compiler (tcc) to provide a just-in-time
900 (JIT) compilation service for FFI.
901 libzmq
903 use constant ZMQ_IO_THREADS => 1;
904 use constant ZMQ_MAX_SOCKETS => 2;
905 use constant ZMQ_REQ => 3;
906 use constant ZMQ_REP => 4;
907 use FFI::CheckLib qw( find_lib_or_exit );
908 use FFI::Platypus 1.00;
909 use FFI::Platypus::Memory qw( malloc );
910 use FFI::Platypus::Buffer qw( scalar_to_buffer buffer_to_scalar );
911 my $endpoint = "ipc://zmq-ffi-$$";
913 my $ffi = FFI::Platypus->new( api => 1 );
914 $ffi->lib(undef); # for puts
916 $ffi->attach(puts => ['string'] => 'int');
917 $ffi->lib(find_lib_or_exit lib => 'zmq');
919 $ffi->attach(zmq_version => ['int*', 'int*', 'int*'] => 'void');
920 my($major,$minor,$patch);
922 zmq_version(\$major, \$minor, \$patch);
923 puts("libzmq version $major.$minor.$patch");
924 die "this script only works with libzmq 3 or better" unless $major >= 3;
925 $ffi->type('opaque' => 'zmq_context');
927 $ffi->type('opaque' => 'zmq_socket');
928 $ffi->type('opaque' => 'zmq_msg_t');
929 $ffi->attach(zmq_ctx_new => [] => 'zmq_context');
930 $ffi->attach(zmq_ctx_set => ['zmq_context', 'int', 'int'] => 'int');
931 $ffi->attach(zmq_socket => ['zmq_context', 'int'] => 'zmq_socket');
932 $ffi->attach(zmq_connect => ['opaque', 'string'] => 'int');
933 $ffi->attach(zmq_bind => ['zmq_socket', 'string'] => 'int');
934 $ffi->attach(zmq_send => ['zmq_socket', 'opaque', 'size_t', 'int'] => 'int');
935 $ffi->attach(zmq_msg_init => ['zmq_msg_t'] => 'int');
936 $ffi->attach(zmq_msg_recv => ['zmq_msg_t', 'zmq_socket', 'int'] => 'int');
937 $ffi->attach(zmq_msg_data => ['zmq_msg_t'] => 'opaque');
938 $ffi->attach(zmq_errno => [] => 'int');
939 $ffi->attach(zmq_strerror => ['int'] => 'string');
940 my $context = zmq_ctx_new();
942 zmq_ctx_set($context, ZMQ_IO_THREADS, 1);
943 my $socket1 = zmq_socket($context, ZMQ_REQ);
945 zmq_connect($socket1, $endpoint);
946 my $socket2 = zmq_socket($context, ZMQ_REP);
948 zmq_bind($socket2, $endpoint);
949 do { # send
951 our $sent_message = "hello there";
952 my($pointer, $size) = scalar_to_buffer $sent_message;
953 my $r = zmq_send($socket1, $pointer, $size, 0);
954 die zmq_strerror(zmq_errno()) if $r == -1;
955 };
956 do { # recv
958 my $msg_ptr = malloc 100;
959 zmq_msg_init($msg_ptr);
960 my $size = zmq_msg_recv($msg_ptr, $socket2, 0);
961 die zmq_strerror(zmq_errno()) if $size == -1;
962 my $data_ptr = zmq_msg_data($msg_ptr);
963 my $recv_message = buffer_to_scalar $data_ptr, $size;
964 print "recv_message = $recv_message\n";
965 };
966 Discussion: ØMQ is a high-performance asynchronous messaging library.
968 There are a few things to note here.
969 Firstly, sometimes there may be multiple versions of a library in the
971 wild and you may need to verify that the library on a system meets your
972 needs (alternatively you could support multiple versions and configure
973 your bindings dynamically). Here we use "zmq_version" to ask libzmq
974 which version it is.
975 "zmq_version" returns the version number via three integer pointer
977 arguments, so we use the pointer to integer type: "int *". In order to
978 pass pointer types, we pass a reference. In this case it is a reference
979 to an undefined value, because zmq_version will write into the pointers
980 the output values, but you can also pass in references to integers,
981 floating point values and opaque pointer types. When the function
982 returns the $major variable (and the others) has been updated and we
983 can use it to verify that it supports the API that we require.
984 Notice that we define three aliases for the "opaque" type:
986 "zmq_context", "zmq_socket" and "zmq_msg_t". While this isn't strictly
987 necessary, since Platypus and C treat all three of these types the
988 same, it is useful form of documentation that helps describe the
989 functionality of the interface.
990 Finally we attach the necessary functions, send and receive a message.
992 If you are interested, there is a fully fleshed out ØMQ Perl interface
993 implemented using FFI called ZMQ::FFI.
994 libarchive
996 use FFI::Platypus 1.00;
997 use FFI::CheckLib qw( find_lib_or_exit );
998 # This example uses FreeBSD's libarchive to list the contents of any
1000 # archive format that it suppors. We've also filled out a part of
1001 # the ArchiveWrite class that could be used for writing archive formats
1002 # supported by libarchive
1003 my $ffi = FFI::Platypus->new( api => 1 );
1005 $ffi->lib(find_lib_or_exit lib => 'archive');
1006 $ffi->type('object(Archive)' => 'archive_t');
1007 $ffi->type('object(ArchiveRead)' => 'archive_read_t');
1008 $ffi->type('object(ArchiveWrite)' => 'archive_write_t');
1009 $ffi->type('object(ArchiveEntry)' => 'archive_entry_t');
1010 package Archive;
1012 # base class is "abstract" having no constructor or destructor
1014 $ffi->mangler(sub {
1016 my($name) = @_;
1017 "archive_$name";
1018 });
1019 $ffi->attach( error_string => ['archive_t'] => 'string' );
1020 package ArchiveRead;
1022 our @ISA = qw( Archive );
1024 $ffi->mangler(sub {
1026 my($name) = @_;
1027 "archive_read_$name";
1028 });
1029 $ffi->attach( new => ['string'] => 'archive_read_t' );
1031 $ffi->attach( [ free => 'DESTROY' ] => ['archive_t'] => 'void' );
1032 $ffi->attach( support_filter_all => ['archive_t'] => 'int' );
1033 $ffi->attach( support_format_all => ['archive_t'] => 'int' );
1034 $ffi->attach( open_filename => ['archive_t','string','size_t'] => 'int' );
1035 $ffi->attach( next_header2 => ['archive_t', 'archive_entry_t' ] => 'int' );
1036 $ffi->attach( data_skip => ['archive_t'] => 'int' );
1037 # ... define additional read methods
1038 package ArchiveWrite;
1040 our @ISA = qw( Archive );
1042 $ffi->mangler(sub {
1044 my($name) = @_;
1045 "archive_write_$name";
1046 });
1047 $ffi->attach( new => ['string'] => 'archive_write_t' );
1049 $ffi->attach( [ free => 'DESTROY' ] => ['archive_write_t'] => 'void' );
1050 # ... define additional write methods
1051 package ArchiveEntry;
1053 $ffi->mangler(sub {
1055 my($name) = @_;
1056 "archive_entry_$name";
1057 });
1058 $ffi->attach( new => ['string'] => 'archive_entry_t' );
1060 $ffi->attach( [ free => 'DESTROY' ] => ['archive_entry_t'] => 'void' );
1061 $ffi->attach( pathname => ['archive_entry_t'] => 'string' );
1062 # ... define additional entry methods
1063 package main;
1065 use constant ARCHIVE_OK => 0;
1067 # this is a Perl version of the C code here:
1069 # https://github.com/libarchive/libarchive/wiki/Examples#List_contents_of_Archive_stored_in_File
1070 my $archive_filename = shift @ARGV;
1072 unless(defined $archive_filename)
1073 {
1074 print "usage: $0 archive.tar\n";
1075 exit;
1076 }
1077 my $archive = ArchiveRead->new;
1079 $archive->support_filter_all;
1080 $archive->support_format_all;
1081 my $r = $archive->open_filename($archive_filename, 1024);
1083 die "error opening $archive_filename: ", $archive->error_string
1084 unless $r == ARCHIVE_OK;
1085 my $entry = ArchiveEntry->new;
1087 while($archive->next_header2($entry) == ARCHIVE_OK)
1089 {
1090 print $entry->pathname, "\n";
1091 $archive->data_skip;
1092 }
1093 Discussion: libarchive is the implementation of "tar" for FreeBSD
1095 provided as a library and available on a number of platforms.
1096 One interesting thing about libarchive is that it provides a kind of
1098 object oriented interface via opaque pointers. This example creates an
1099 abstract class "Archive", and concrete classes "ArchiveWrite",
1100 "ArchiveRead" and "ArchiveEntry". The concrete classes can even be
1101 inherited from and extended just like any Perl classes because of the
1102 way the custom types are implemented. We use Platypus's "object" type
1103 for this implementation, which is a wrapper around an "opaque" (can
1104 also be an integer) type that is blessed into a particular class.
1105 Another advanced feature of this example is that we define a mangler to
1107 modify the symbol resolution for each class. This means we can do this
1108 when we define a method for Archive:
1109 $ffi->attach( support_filter_all => ['archive_t'] => 'int' );
1111 Rather than this:
1113 $ffi->attach(
1115 [ archive_read_support_filter_all => 'support_read_filter_all' ] =>
1116 ['archive_t'] => 'int' );
1117 );
1118 unix open
1120 use FFI::Platypus 1.00;
1121 {
1123 package FD;
1124 use constant O_RDONLY => 0;
1126 use constant O_WRONLY => 1;
1127 use constant O_RDWR => 2;
1128 use constant IN => bless \do { my $in=0 }, __PACKAGE__;
1130 use constant OUT => bless \do { my $out=1 }, __PACKAGE__;
1131 use constant ERR => bless \do { my $err=2 }, __PACKAGE__;
1132 my $ffi = FFI::Platypus->new( api => 1, lib => [undef]);
1134 $ffi->type('object(FD,int)' => 'fd');
1136 $ffi->attach( [ 'open' => 'new' ] => [ 'string', 'int', 'mode_t' ] => 'fd' => sub {
1138 my($xsub, $class, $fn, @rest) = @_;
1139 my $fd = $xsub->($fn, @rest);
1140 die "error opening $fn $!" if $$fd == -1;
1141 $fd;
1142 });
1143 $ffi->attach( write => ['fd', 'string', 'size_t' ] => 'ssize_t' );
1145 $ffi->attach( read => ['fd', 'string', 'size_t' ] => 'ssize_t' );
1146 $ffi->attach( close => ['fd'] => 'int' );
1147 }
1148 my $fd = FD->new("$0", FD::O_RDONLY);
1150 my $buffer = "\0" x 10;
1152 while(my $br = $fd->read($buffer, 10))
1154 {
1155 FD::OUT->write($buffer, $br);
1156 }
1157 $fd->close;
1159 Discussion: The Unix file system calls use an integer handle for each
1161 open file. We can use the same "object" type that we used for
1162 libarchive above, except we let platypus know that the underlying type
1163 is "int" instead of "opaque" (the latter being the default for the
1164 "object" type). Mainly just for demonstration since Perl has much
1165 better IO libraries, but now we have an OO interface to the Unix IO
1166 functions.
1167 bzip2
1169 use FFI::Platypus 1.00;
1170 use FFI::CheckLib qw( find_lib_or_die );
1171 use FFI::Platypus::Buffer qw( scalar_to_buffer buffer_to_scalar );
1172 use FFI::Platypus::Memory qw( malloc free );
1173 my $ffi = FFI::Platypus->new( api => 1 );
1175 $ffi->lib(find_lib_or_die lib => 'bz2');
1176 $ffi->attach(
1178 [ BZ2_bzBuffToBuffCompress => 'compress' ] => [
1179 'opaque', # dest
1180 'unsigned int *', # dest length
1181 'opaque', # source
1182 'unsigned int', # source length
1183 'int', # blockSize100k
1184 'int', # verbosity
1185 'int', # workFactor
1186 ] => 'int',
1187 sub {
1188 my $sub = shift;
1189 my($source,$source_length) = scalar_to_buffer $_[0];
1190 my $dest_length = int(length($source)*1.01) + 1 + 600;
1191 my $dest = malloc $dest_length;
1192 my $r = $sub->($dest, \$dest_length, $source, $source_length, 9, 0, 30);
1193 die "bzip2 error $r" unless $r == 0;
1194 my $compressed = buffer_to_scalar($dest, $dest_length);
1195 free $dest;
1196 $compressed;
1197 },
1198 );
1199 $ffi->attach(
1201 [ BZ2_bzBuffToBuffDecompress => 'decompress' ] => [
1202 'opaque', # dest
1203 'unsigned int *', # dest length
1204 'opaque', # source
1205 'unsigned int', # source length
1206 'int', # small
1207 'int', # verbosity
1208 ] => 'int',
1209 sub {
1210 my $sub = shift;
1211 my($source, $source_length) = scalar_to_buffer $_[0];
1212 my $dest_length = $_[1];
1213 my $dest = malloc $dest_length;
1214 my $r = $sub->($dest, \$dest_length, $source, $source_length, 0, 0);
1215 die "bzip2 error $r" unless $r == 0;
1216 my $decompressed = buffer_to_scalar($dest, $dest_length);
1217 free $dest;
1218 $decompressed;
1219 },
1220 );
1221 my $original = "hello compression world\n";
1223 my $compressed = compress($original);
1224 print decompress($compressed, length $original);
1225 Discussion: bzip2 is a compression library. For simple one shot
1227 attempts at compression/decompression when you expect the original and
1228 the result to fit within memory it provides two convenience functions
1229 "BZ2_bzBuffToBuffCompress" and "BZ2_bzBuffToBuffDecompress".
1230 The first four arguments of both of these C functions are identical,
1232 and represent two buffers. One buffer is the source, the second is the
1233 destination. For the destination, the length is passed in as a pointer
1234 to an integer. On input this integer is the size of the destination
1235 buffer, and thus the maximum size of the compressed or decompressed
1236 data. When the function returns the actual size of compressed or
1237 compressed data is stored in this integer.
1238 This is normal stuff for C, but in Perl our buffers are scalars and
1240 they already know how large they are. In this sort of situation,
1241 wrapping the C function in some Perl code can make your interface a
1242 little more Perl like. In order to do this, just provide a code
1243 reference as the last argument to the "attach" method. The first
1244 argument to this wrapper will be a code reference to the C function.
1245 The Perl arguments will come in after that. This allows you to modify
1246 / convert the arguments to conform to the C API. What ever value you
1247 return from the wrapper function will be returned back to the original
1248 caller.
1249 The Win32 API
1251 use utf8;
1252 use FFI::Platypus 1.00;
1253 my $ffi = FFI::Platypus->new(
1255 api => 1,
1256 lib => [undef],
1257 );
1258 # see FFI::Platypus::Lang::Win32
1260 $ffi->lang('Win32');
1261 # Send a Unicode string to the Windows API MessageBoxW function.
1263 use constant MB_OK => 0x00000000;
1264 use constant MB_DEFAULT_DESKTOP_ONLY => 0x00020000;
1265 $ffi->attach( [MessageBoxW => 'MessageBox'] => [ 'HWND', 'LPCWSTR', 'LPCWSTR', 'UINT'] => 'int' );
1266 MessageBox(undef, "I ❤️ Platypus", "Confession", MB_OK|MB_DEFAULT_DESKTOP_ONLY);
1267 Discussion: The API used by Microsoft Windows present some unique
1269 challenges. On 32 bit systems a different ABI is used than what is
1270 used by the standard C library. It also provides a rats nest of type
1271 aliases. Finally if you want to talk Unicode to any of the Windows API
1272 you will need to use "UTF-16LE" instead of "utf-8" which is native to
1273 Perl. (The Win32 API refers to these as "LPWSTR" and "LPCWSTR" types).
1274 As much as possible the Win32 "language" plugin attempts to handle this
1275 transparently. For more details see FFI::Platypus::Lang::Win32.
1276 bundle your own code
1278 "ffi/foo.c":
1279 #include <ffi_platypus_bundle.h>
1281 #include <string.h>
1282 typedef struct {
1284 char *name;
1285 int value;
1286 } foo_t;
1287 foo_t*
1289 foo__new(const char *class_name, const char *name, int value)
1290 {
1291 (void)class_name;
1292 foo_t *self = malloc( sizeof( foo_t ) );
1293 self->name = strdup(name);
1294 self->value = value;
1295 return self;
1296 }
1297 const char *
1299 foo__name(foo_t *self)
1300 {
1301 return self->name;
1302 }
1303 int
1305 foo__value(foo_t *self)
1306 {
1307 return self->value;
1308 }
1309 void
1311 foo__DESTROY(foo_t *self)
1312 {
1313 free(self->name);
1314 free(self);
1315 }
1316 "lib/Foo.pm":
1318 package Foo;
1320 use strict;
1322 use warnings;
1323 use FFI::Platypus 1.00;
1324 {
1326 my $ffi = FFI::Platypus->new( api => 1 );
1327 $ffi->type('object(Foo)' => 'foo_t');
1329 $ffi->mangler(sub {
1330 my $name = shift;
1331 $name =~ s/^/foo__/;
1332 $name;
1333 });
1334 $ffi->bundle;
1336 $ffi->attach( new => [ 'string', 'string', 'int' ] => 'foo_t' );
1338 $ffi->attach( name => [ 'foo_t' ] => 'string' );
1339 $ffi->attach( value => [ 'foo_t' ] => 'int' );
1340 $ffi->attach( DESTROY => [ 'foo_t' ] => 'void' );
1341 }
1342 1;
1344 You can bundle your own C (or other compiled language) code with your
1346 Perl extension. Sometimes this is helpful for smoothing over the
1347 interface of a C library which is not very FFI friendly. Sometimes you
1348 may want to write some code in C for a tight loop. Either way, you can
1349 do this with the Platypus bundle interface. See FFI::Platypus::Bundle
1350 for more details.
1351 Also related is the bundle constant interface, which allows you to
1353 define Perl constants in C space. See FFI::Platypus::Constant for
1354 details.
1355
1357 How do I get constants defined as macros in C header files
1358 This turns out to be a challenge for any language calling into C, which
1359 frequently uses "#define" macros to define constants like so:
1360 #define FOO_STATIC 1
1362 #define FOO_DYNAMIC 2
1363 #define FOO_OTHER 3
1364 As macros are expanded and their definitions are thrown away by the C
1366 pre-processor there isn't any way to get the name/value mappings from
1367 the compiled dynamic library.
1368 You can manually create equivalent constants in your Perl source:
1370 use constant FOO_STATIC => 1;
1372 use constant FOO_DYNAMIC => 2;
1373 use constant FOO_OTHER => 3;
1374 If there are a lot of these types of constants you might want to
1376 consider using a tool (Convert::Binary::C can do this) that can extract
1377 the constants for you.
1378 See also the "Integer constants" example in FFI::Platypus::Type.
1380 You can also use the new Platypus bundle interface to define Perl
1382 constants from C space. This is more reliable, but does require a
1383 compiler at install time. It is recommended mainly for writing
1384 bindings against libraries that have constants that can vary widely
1385 from platform to platform. See FFI::Platypus::Constant for details.
1386 What about enums?
1388 The C enum types are integers. The underlying type is up to the
1389 platform, so Platypus provides "enum" and "senum" types for unsigned
1390 and singed enums respectively. At least some compilers treat signed
1391 and unsigned enums as different types. The enum values are essentially
1392 the same as macro constants described above from an FFI perspective.
1393 Thus the process of defining enum values is identical to the process of
1394 defining macro constants in Perl.
1395 For more details on enumerated types see "Enum types" in
1397 FFI::Platypus::Type.
1398 There is also a type plugin (FFI::Platypus::Type::Enum) that can be
1400 helpful in writing interfaces that use enums.
1401 Memory leaks
1403 There are a couple places where memory is allocated, but never
1404 deallocated that may look like memory leaks by tools designed to find
1405 memory leaks like valgrind. This memory is intended to be used for the
1406 lifetime of the perl process so there normally this isn't a problem
1407 unless you are embedding a Perl interpreter which doesn't closely match
1408 the lifetime of your overall application.
1409 Specifically:
1411 type cache
1413 some types are cached and not freed. These are needed as long as
1414 there are FFI functions that could be called.
1415 attached functions
1417 Attaching a function as an xsub will definitely allocate memory
1418 that won't be freed because the xsub could be called at any time,
1419 including in "END" blocks.
1420 The Platypus team plans on adding a hook to free some of this "leaked"
1422 memory for use cases where Perl and Platypus are embedded in a larger
1423 application where the lifetime of the Perl process is significantly
1424 smaller than the overall lifetime of the whole process.
1425 I get seg faults on some platforms but not others with a library using
1427 pthreads.
1428 On some platforms, Perl isn't linked with "libpthreads" if Perl threads
1429 are not enabled. On some platforms this doesn't seem to matter,
1430 "libpthreads" can be loaded at runtime without much ill-effect. (Linux
1431 from my experience doesn't seem to mind one way or the other). Some
1432 platforms are not happy about this, and about the only thing that you
1433 can do about it is to build Perl such that it links with "libpthreads"
1434 even if it isn't a threaded Perl.
1435 This is not really an FFI issue, but a Perl issue, as you will have the
1437 same problem writing XS code for the such libraries.
1438 Doesn't work on Perl 5.10.0.
1440 I try as best as possible to support the same range of Perls as the
1441 Perl toolchain. That means all the way back to 5.8.1. Unfortunately,
1442 5.10.0 seems to have a problem that is difficult to diagnose. Patches
1443 to fix are welcome, if you want to help out on this, please see:
1444 <https://github.com/PerlFFI/FFI-Platypus/issues/68>
1446 Since this is an older buggy version of Perl it is recommended that you
1448 instead upgrade to 5.10.1 or later.
1449
1451 Platypus and Native Interfaces like libffi rely on the availability of
1452 dynamic libraries. Things not supported include:
1453 Systems that lack dynamic library support
1455 Like MS-DOS
1456 Systems that are not supported by libffi
1458 Like OpenVMS
1459 Languages that do not support using dynamic libraries from other
1461 languages
1462 Like older versions of Google's Go. This is a problem for C / XS
1463 code as well.
1464 Languages that do not compile to machine code
1466 Like .NET based languages and Java.
1467 The documentation has a bias toward using FFI / Platypus with C. This
1469 is my fault, as my background in mainly in C/C++ programmer (when I am
1470 not writing Perl). In many places I use "C" as a short form for "any
1471 language that can generate machine code and is callable from C". I
1472 welcome pull requests to the Platypus core to address this issue. In
1473 an attempt to ease usage of Platypus by non C programmers, I have
1474 written a number of foreign language plugins for various popular
1475 languages (see the SEE ALSO below). These plugins come with examples
1476 specific to those languages, and documentation on common issues related
1477 to using those languages with FFI. In most cases these are available
1478 for easy adoption for those with the know-how or the willingness to
1479 learn. If your language doesn't have a plugin YET, that is just
1480 because you haven't written it yet.
1481
1483 IRC: #native on irc.perl.org
1484 (click for instant chat room login)
1486 <http://chat.mibbit.com/#native@irc.perl.org>
1487 If something does not work the way you think it should, or if you have
1489 a feature request, please open an issue on this project's GitHub Issue
1490 tracker:
1491 <https://github.com/perlFFI/FFI-Platypus/issues>
1493
1495 If you have implemented a new feature or fixed a bug then you may make
1496 a pull request on this project's GitHub repository:
1497 <https://github.com/PerlFFI/FFI-Platypus/pulls>
1499 This project is developed using Dist::Zilla. The project's git
1501 repository also comes with the "Makefile.PL" file necessary for
1502 building, testing (and even installing if necessary) without
1503 Dist::Zilla. Please keep in mind though that these files are generated
1504 so if changes need to be made to those files they should be done
1505 through the project's "dist.ini" file. If you do use Dist::Zilla and
1506 already have the necessary plugins installed, then I encourage you to
1507 run "dzil test" before making any pull requests. This is not a
1508 requirement, however, I am happy to integrate especially smaller
1509 patches that need tweaking to fit the project standards. I may push
1510 back and ask you to write a test case or alter the formatting of a
1511 patch depending on the amount of time I have and the amount of code
1512 that your patch touches.
1513 This project's GitHub issue tracker listed above is not Write-Only. If
1515 you want to contribute then feel free to browse through the existing
1516 issues and see if there is something you feel you might be good at and
1517 take a whack at the problem. I frequently open issues myself that I
1518 hope will be accomplished by someone in the future but do not have time
1519 to immediately implement myself.
1520 Another good area to help out in is documentation. I try to make sure
1522 that there is good document coverage, that is there should be
1523 documentation describing all the public features and warnings about
1524 common pitfalls, but an outsider's or alternate view point on such
1525 things would be welcome; if you see something confusing or lacks
1526 sufficient detail I encourage documentation only pull requests to
1527 improve things.
1528 The Platypus distribution comes with a test library named "libtest"
1530 that is normally automatically built by "./Build test". If you prefer
1531 to use "prove" or run tests directly, you can use the "./Build libtest"
1532 command to build it. Example:
1533 % perl Makefile.PL
1535 % make
1536 % make ffi-test
1537 % prove -bv t
1538 # or an individual test
1539 % perl -Mblib t/ffi_platypus_memory.t
1540 The build process also respects these environment variables:
1542 FFI_PLATYPUS_DEBUG_FAKE32
1544 When building Platypus on 32 bit Perls, it will use the Math::Int64
1545 C API and make Math::Int64 a prerequisite. Setting this
1546 environment variable will force Platypus to build with both of
1547 those options on a 64 bit Perl as well.
1548 % env FFI_PLATYPUS_DEBUG_FAKE32=1 perl Makefile.PL
1550 DEBUG_FAKE32:
1551 + making Math::Int64 a prereq
1552 + Using Math::Int64's C API to manipulate 64 bit values
1553 Generating a Unix-style Makefile
1554 Writing Makefile for FFI::Platypus
1555 Writing MYMETA.yml and MYMETA.json
1556 %
1557 FFI_PLATYPUS_NO_ALLOCA
1559 Platypus uses the non-standard and somewhat controversial C
1560 function "alloca" by default on platforms that support it. I
1561 believe that Platypus uses it responsibly to allocate small amounts
1562 of memory for argument type parameters, and does not use it to
1563 allocate large structures like arrays or buffers. If you prefer
1564 not to use "alloca" despite these precautions, then you can turn
1565 its use off by setting this environment variable when you run
1566 "Makefile.PL":
1567 helix% env FFI_PLATYPUS_NO_ALLOCA=1 perl Makefile.PL
1569 NO_ALLOCA:
1570 + alloca() will not be used, even if your platform supports it.
1571 Generating a Unix-style Makefile
1572 Writing Makefile for FFI::Platypus
1573 Writing MYMETA.yml and MYMETA.json
1574 V When building platypus may hide some of the excessive output when
1576 probing and building, unless you set "V" to a true value.
1577 % env V=1 perl Makefile.PL
1579 % make V=1
1580 ...
1581 Coding Guidelines
1583 • Do not hesitate to make code contribution. Making useful
1584 contributions is more important than following byzantine
1585 bureaucratic coding regulations. We can always tweak things later.
1586 • Please make an effort to follow existing coding style when making
1588 pull requests.
1589 • Platypus supports all production Perl releases since 5.8.1. For
1591 that reason, please do not introduce any code that requires a newer
1592 version of Perl.
1593 Performance Testing
1595 As Mark Twain was fond of saying there are four types of lies: lies,
1596 damn lies, statistics and benchmarks. That being said, it can
1597 sometimes be helpful to compare the runtime performance of Platypus if
1598 you are making significant changes to the Platypus Core. For that I
1599 use `FFI-Performance`, which can be found in my GitHub repository here:
1600 <https://github.com/PerlFFI/FFI-Performance>
1602 System integrators
1604 This distribution uses Alien::FFI in fallback mode, meaning if the
1605 system doesn't provide "pkg-config" and "libffi" it will attempt to
1606 download "libffi" and build it from source. If you are including
1607 Platypus in a larger system (for example a Linux distribution) you only
1608 need to make sure to declare "pkg-config" or "pkgconf" and the
1609 development package for "libffi" as prereqs for this module.
1610
1612 NativeCall
1613 Promising interface to Platypus inspired by Perl 6.
1614 FFI::Platypus::Type
1616 Type definitions for Platypus.
1617 FFI::Platypus::Record
1619 Define structured data records (C "structs") for use with Platypus.
1620 FFI::C
1622 Another interface for defining structured data records for use with
1623 Platypus. Its advantage over FFI::Platypus::Record is that it
1624 supports "union"s and nested data structures. Its disadvantage is
1625 that it doesn't support passing "struct"s by-value.
1626 FFI::Platypus::API
1628 The custom types API for Platypus.
1629 FFI::Platypus::Memory
1631 Memory functions for FFI.
1632 FFI::CheckLib
1634 Find dynamic libraries in a portable way.
1635 FFI::TinyCC
1637 JIT compiler for FFI.
1638 FFI::Platypus::Lang::C
1640 Documentation and tools for using Platypus with the C programming
1641 language
1642 FFI::Platypus::Lang::CPP
1644 Documentation and tools for using Platypus with the C++ programming
1645 language
1646 FFI::Platypus::Lang::Fortran
1648 Documentation and tools for using Platypus with Fortran
1649 FFI::Platypus::Lang::Go
1651 Documentation and tools for using Platypus with Go
1652 FFI::Platypus::Lang::Pascal
1654 Documentation and tools for using Platypus with Free Pascal
1655 FFI::Platypus::Lang::Rust
1657 Documentation and tools for using Platypus with the Rust
1658 programming language
1659 FFI::Platypus::Lang::ASM
1661 Documentation and tools for using Platypus with the Assembly
1662 FFI::Platypus::Lang::Win32
1664 Documentation and tools for using Platypus with the Win32 API.
1665 Wasm and Wasm::Wasmtime
1667 Modules for writing WebAssembly bindings in Perl. This allows you
1668 to call functions written in any language supported by WebAssembly.
1669 These modules are also implemented using Platypus.
1670 Convert::Binary::C
1672 A great interface for decoding C data structures, including
1673 "struct"s, "enum"s, "#define"s and more.
1674 pack and unpack
1676 Native to Perl functions that can be used to decode C "struct"
1677 types.
1678 C::Scan
1680 This module can extract constants and other useful objects from C
1681 header files that may be relevant to an FFI application. One
1682 downside is that its use may require development packages to be
1683 installed.
1684 Win32::API
1686 Microsoft Windows specific FFI style interface.
1687 Ctypes <https://gitorious.org/perl-ctypes>
1689 Ctypes was intended as a FFI style interface for Perl, but was
1690 never part of CPAN, and at least the last time I tried it did not
1691 work with recent versions of Perl.
1692 FFI Older, simpler, less featureful FFI. It used to be implemented
1694 using FSF's "ffcall". Because "ffcall" has been unsupported for
1695 some time, I reimplemented this module using FFI::Platypus.
1696 C::DynaLib
1698 Another FFI for Perl that doesn't appear to have worked for a long
1699 time.
1700 C::Blocks
1702 Embed a tiny C compiler into your Perl scripts.
1703 Alien::FFI
1705 Provides libffi for Platypus during its configuration and build
1706 stages.
1707 P5NCI
1709 Yet another FFI like interface that does not appear to be supported
1710 or under development anymore.
1711
1713 In addition to the contributors mentioned below, I would like to
1714 acknowledge Brock Wilcox (AWWAIID) and Meredith Howard (MHOWARD) whose
1715 work on "FFI::Sweet" not only helped me get started with FFI but
1716 significantly influenced the design of Platypus.
1717 Dan Book, who goes by Grinnz on IRC for answering user questions about
1719 FFI and Platypus.
1720 In addition I'd like to thank Alessandro Ghedini (ALEXBIO) whose work
1722 on another Perl FFI library helped drive some of the development ideas
1723 for FFI::Platypus.
1724
1726 Author: Graham Ollis <plicease@cpan.org>
1727 Contributors:
1729 Bakkiaraj Murugesan (bakkiaraj)
1731 Dylan Cali (calid)
1733 pipcet
1735 Zaki Mughal (zmughal)
1737 Fitz Elliott (felliott)
1739 Vickenty Fesunov (vyf)
1741 Gregor Herrmann (gregoa)
1743 Shlomi Fish (shlomif)
1745 Damyan Ivanov
1747 Ilya Pavlov (Ilya33)
1749 Petr Pisar (ppisar)
1751 Mohammad S Anwar (MANWAR)
1753 Håkon Hægland (hakonhagland, HAKONH)
1755 Meredith (merrilymeredith, MHOWARD)
1757 Diab Jerius (DJERIUS)
1759 Eric Brine (IKEGAMI)
1761 szTheory
1763
1765 This software is copyright (c) 2015,2016,2017,2018,2019,2020 by Graham
1766 Ollis.
1767 This is free software; you can redistribute it and/or modify it under
1769 the same terms as the Perl 5 programming language system itself.
1770perl v5.32.1 2021-03-18 FFI::Platypus(3)