FFI-Platypus-Lang-Rust
所属分类：collect
开发工具：Perl
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上传日期：2023-06-14 23:06:10
上 传 者：
sh-1993
说明： 使用Platypus和Rust编程语言的文档和工具，
(Documentation and tools for using Platypus with the Rust programming language,)
文件列表:
Changes (2725, 2023-08-22)
author.yml (448, 2023-08-22)
dist.ini (1246, 2023-08-22)
examples/ (0, 2023-08-22)
examples/Person/ (0, 2023-08-22)
examples/Person/Makefile.PL (711, 2023-08-22)
examples/Person/ffi/ (0, 2023-08-22)
examples/Person/ffi/Cargo.toml (253, 2023-08-22)
examples/Person/ffi/src/ (0, 2023-08-22)
examples/Person/ffi/src/lib.rs (1873, 2023-08-22)
examples/Person/ffi/src/test.rs (1317, 2023-08-22)
examples/Person/lib/ (0, 2023-08-22)
examples/Person/lib/Person.pm (737, 2023-08-22)
examples/Person/t/ (0, 2023-08-22)
examples/Person/t/basic.t (241, 2023-08-22)
examples/add.pl (427, 2023-08-22)
examples/add.rs (99, 2023-08-22)
examples/callback.pl (551, 2023-08-22)
examples/callback.rs (461, 2023-08-22)
examples/old/ (0, 2023-08-22)
examples/old/points.pl (657, 2023-08-22)
examples/old/points.rs (1011, 2023-08-22)
examples/panic.pl (450, 2023-08-22)
examples/panic.rs (335, 2023-08-22)
examples/slice.pl (516, 2023-08-22)
examples/slice.rs (331, 2023-08-22)
examples/string/ (0, 2023-08-22)
examples/string/argument.pl (536, 2023-08-22)
examples/string/argument.rs (342, 2023-08-22)
examples/string/return/ (0, 2023-08-22)
examples/string/return/keep.pl (452, 2023-08-22)
... ...
# FFI::Platypus::Lang::Rust  
Documentation and tools for using Platypus with the Rust programming language
# SYNOPSIS
Rust:
```
#![crate_type = "cdylib"]
#[no_mangle]
pub extern "C" fn add(a: i32, b: i32) -> i32 {
a + b
}
```
Perl:
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'add',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->attach( add => ['i32', 'i32'] => 'i32' );
print add(1,2), "\n"; # prints 3
```
# DESCRIPTION
This module provides native Rust types for [FFI::Platypus](https://metacpan.org/pod/FFI::Platypus) in order to
reduce cognitive load and concentrate on Rust and forget about C types.
This document also documents issues and caveats that I have discovered
in my attempts to work with Rust and FFI.
Note that in addition to using pre-compiled Rust libraries, you can
bundle Rust code with your Perl distribution using [FFI::Build](https://metacpan.org/pod/FFI::Build) and
[FFI::Build::File::Cargo](https://metacpan.org/pod/FFI::Build::File::Cargo).
# EXAMPLES
The examples in this discussion are bundled with this distribution and
can be found in the `examples` directory.
## Passing and Returning Integers
### Rust Source
```
#![crate_type = "cdylib"]
#[no_mangle]
pub extern "C" fn add(a: i32, b: i32) -> i32 {
a + b
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'add',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->attach( add => ['i32', 'i32'] => 'i32' );
print add(1,2), "\n"; # prints 3
```
### Execute
```
$ rustc add.rs
$ perl add.pl
3
```
### Notes
Basic types like integers and floating points are the easiest to pass
across the FFI boundary. The Platypus Rust language plugin (this module)
provides the basic types used by Rust (for example: `bool`, `i32`, `u64`,
`f64`, `isize` and others) will all work as a Rust programmer would expect.
This is nice because you don't have to think about what the equivalent types
would be in C when you are writing your Perl extension in Rust.
Rust symbols are "mangled" by default, which means that you cannot use
the name of the function from the source code without knowing what the
mangled name is. Rust provides a function attribute `#[no_mangle]`
which will tell the compiler not to mangle the name, making lookup of
the symbol possible from other programming languages like Perl.
Rust functions do not use the same ABI as C by default, so if you want
to be able to call Rust functions from Perl they need to be declared
as `extern "C"` as in this example.
We also set the "crate type" to `cdylib` in the first line to tell the
Rust compiler to generate a dynamic library that will be consumed by
a non-Rust language like Perl.
## String Arguments
### Rust Source
```perl
#![crate_type = "cdylib"]
use std::ffi::CStr;
use std::os::raw::c_char;
#[no_mangle]
pub extern "C" fn how_many_characters(s: *const c_char) -> isize {
if s.is_null() {
return -1;
}
let s = unsafe { CStr::from_ptr(s) };
match s.to_str() {
Ok(s) => s.chars().count() as isize,
Err(_) => -2,
}
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'argument',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->attach( how_many_characters => ['string'] => 'isize' );
print how_many_characters(undef), "\n"; # prints -1
print how_many_characters("frooble bits"), "\n"; # prints 12
```
### Execute
```
$ rustc argument.rs
$ perl argument.pl
-1
12
```
### Notes
Strings are considerably more complicated for a number of reasons,
but for passing them into Rust code the main challenge is that the
representation is different from what C uses. C Uses NULL terminated
strings and Rust uses a pointer and size combination that allows
NULLs inside strings. Perls internal representation of strings is
actually closer to what Rust uses, but when Perl talks to other
languages it typically uses C Strings.
Getting a Rust string slice `&str` requires a few stems
- We have to ensure the C pointer is not `NULL`
We return `-1` to indicate an error here. As we can see from the
calling Perl code passing an `undef` from Perl is equivalent to
passing in `NULL` from C.
- Wrap using `Cstr`
We then wrap the pointer using an `unsafe` block. Even though
we know at this point that the pointer cannot be `NULL` it could
technically be pointing to uninitialized or unaddressable memory.
This `unsafe` block is unfortunately necessary, though it is
relatively isolated so it is easy to reason about and review.
- Convert to UTF-8
If the string that we passed in is valid UTF-8 we can convert
it to a `&str` using `to_str` and compute the length of the
string. Otherwise, we return -2 error.
(This example is based on one provided in the
[Rust FFI Omnibus](http://jakegoulding.com/rust-ffi-omnibus/string_arguments/))
## Returning allocated strings
### Rust Source
```perl
#![crate_type = "cdylib"]
use std::ffi::CString;
use std::iter;
use std::os::raw::c_char;
#[no_mangle]
pub extern "C" fn theme_song_generate(length: u8) -> *mut c_char {
let mut song = String::from(" ");
song.extend(iter::repeat("na ").take(length as usize));
song.push_str("Batman! ");
let c_str_song = CString::new(song).unwrap();
c_str_song.into_raw()
}
#[no_mangle]
pub extern "C" fn theme_song_free(s: *mut c_char) {
if s.is_null() {
return;
}
unsafe { CString::from_raw(s) };
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'return',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->attach( theme_song_free => ['opaque'] => 'void' );
$ffi->attach( theme_song_generate => ['u8'] => 'opaque' => sub {
my($xsub, $length) = @_;
my $ptr = $xsub->($length);
my $str = $ffi->cast( 'opaque' => 'string', $ptr );
theme_song_free($ptr);
$str;
});
print theme_song_generate(42), "\n";
```
### Execute
```
$ rustc return.rs
$ perl return.pl
na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na Batman!
```
### Notes
The big challenge of returning strings from Rust into Perl is
handling the ownership. In this example we have a C API implemented
in Rust that returns a C NULL terminated string, but we have to
pass it back into Rust in order to deallocate it when we are done.
Unfortunately Platypus' `string` type assumes that the callee
retains ownership of the returned string, so we have to get the
pointer instead as an `opaque` so that we can later free it.
Before freeing it though we cast it into a Perl string.
In order to hide the complexities from caller of our
`theme_song_generate` function, we use a function wrapper to
do all of that for us.
(This example is based on one provided in the
[Rust FFI Omnibus](http://jakegoulding.com/rust-ffi-omnibus/string_return/))
## Returning allocated strings, but keeping ownership
### Rust Source
```perl
#![crate_type = "cdylib"]
use std::cell::RefCell;
use std::ffi::CString;
use std::iter;
use std::os::raw::c_char;
#[no_mangle]
pub extern "C" fn theme_song_generate(length: u8) -> *const c_char {
thread_local! {
static KEEP: RefCell> = RefCell::new(None);
}
let mut song = String::from(" ");
song.extend(iter::repeat("na ").take(length as usize));
song.push_str("Batman! ");
let c_str_song = CString::new(song).unwrap();
let ptr = c_str_song.as_ptr();
KEEP.with(|k| {
*k.borrow_mut() = Some(c_str_song);
});
ptr
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'keep',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->attach( theme_song_generate => ['u8'] => 'string' );
print theme_song_generate($_), "\n" for 1..10;
```
### Execute
```
$ rustc keep.rs
$ perl keep.pl
na Batman!
na na Batman!
na na na Batman!
na na na na Batman!
na na na na na Batman!
na na na na na na Batman!
na na na na na na na Batman!
na na na na na na na na Batman!
na na na na na na na na na Batman!
na na na na na na na na na na Batman!
```
### Notes
For frequently called functions with smaller strings it may make more
sense to keep ownership of the string and just return a pointer. Perl
makes its own copy on return anyway when you use the `string` type.
In this example we use thread local storage to keep the `CString`
until the next call when it will be freed. Since we are using thread
local storage, it should even be safe to use this interface from a
threaded Perl program (although you should probably not be using
threaded Perl).
(This example is based on one provided in the
[Rust FFI Omnibus](http://jakegoulding.com/rust-ffi-omnibus/string_arguments/))
## Return static strings
### Rust Source
```
#![crate_type = "cdylib"]
#[no_mangle]
pub extern "C" fn hello_rust() -> *const u8 {
"Hello, world!\0".as_ptr()
}
```
### Perl Source
```perl
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
use FFI::Platypus 1.00;
my $ffi = FFI::Platypus->new( api => 1, lang => 'Rust');
$ffi->lang('Rust');
$ffi->lib(
find_lib_or_die(
lib => 'static',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->lib('./libstring.so');
$ffi->attach(hello_rust => [] => 'string');
print hello_rust(), "\n";
```
### Execute
```
$ rustc static.rs
$ perl static.pl
Hello, world!
```
### Notes
Sometimes you just want to return a static NULL terminated string
from Rust to Perl. This can sometimes be useful for returning
error messages.
## Callbacks
### Rust Source
```perl
#![crate_type = "cdylib"]
use std::ffi::CString;
use std::os::raw::c_char;
type PerlLog = extern "C" fn(line: *const c_char);
#[no_mangle]
pub extern "C" fn rust_log(logf: PerlLog) {
let lines: [&str; 3] = ["Hello from rust!", "Something else.", "The last log line"];
for line in lines.iter() {
// convert string slice to a C style NULL terminated string
let line = CString::new(*line).unwrap();
logf(line.as_ptr());
}
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'callback',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->type( '(string)->void' => 'PerlLog' );
$ffi->attach( rust_log => ['PerlLog'] );
my $perl_log = $ffi->closure(sub {
my $message = shift;
print "log> $message\n";
});
rust_log($perl_log);
```
### Execute
```
$ rustc callback.rs
$ perl callback.pl
log> Hello from rust!
log> Something else.
log> The last log line
```
### Notes
Calling back into Perl from Rust is easy, so long as you have the correct
types defined. The above Rust function takes a C function pointer. We
can crate a Platypus closure object from Perl from a plain Perl sub and
pass the closure into Rust.
## Slice arguments
### Rust Source
```perl
#![crate_type = "cdylib"]
use std::slice;
#[no_mangle]
pub extern "C" fn sum_of_even(numbers: *const u32, len: usize) -> i64 {
if numbers.is_null() {
return -1;
}
let numbers = unsafe { slice::from_raw_parts(numbers, len) };
let sum: u32 = numbers.iter().filter(|&v| v % 2 == 0).sum();
sum as i64
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'slice',
libpath => [dirname __FILE__],
systempath => [],
)
);
$ffi->attach( sum_of_even => ['u32*', 'usize'] => 'i64' );
print sum_of_even(undef, 0), "\n"; # print -1
print sum_of_even([1,2,3,4,5,6], 6), "\n"; # print 12
```
### Execute
```
$ rustc slice.rs
$ perl slice.pl
-1
12
```
### Notes
A Rust slice is a pointer to a chunk of homogeneous data, and the
number of elements in the slice. We can pass these two pieces in
from Perl and combine them into a slice in Rust.
This example sums the even numbers from a slice and returns the
result.
(This example is based on one provided in the
[Rust FFI Omnibus](http://jakegoulding.com/rust-ffi-omnibus/slice_arguments/))
## Tuples
### Rust Source
```perl
#![crate_type = "cdylib"]
use std::convert::From;
// A Rust function that accepts a tuple
fn flip_things_around_rust(tup: (u32, u32)) -> (u32, u32) {
let (a, b) = tup;
(b + 1, a - 1)
}
// A struct that can be passed between C and Rust
#[repr(C)]
pub struct Tuple {
x: u32,
y: u32,
}
// Conversion functions
impl From<(u32, u32)> for Tuple {
fn from(tup: (u32, u32)) -> Tuple {
Tuple { x: tup.0, y: tup.1 }
}
}
impl From for (u32, u32) {
fn from(tup: Tuple) -> (u32, u32) {
(tup.x, tup.y)
}
}
// The exported C method
#[no_mangle]
pub extern "C" fn flip_things_around(tup: Tuple) -> Tuple {
flip_things_around_rust(tup.into()).into()
}
```
### Perl Source
```perl
use FFI::Platypus 2.00;
use FFI::CheckLib qw( find_lib_or_die );
use File::Basename qw( dirname );
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
$ffi->lib(
find_lib_or_die(
lib => 'tuple',
libpath => [dirname __FILE__],
systempath => [],
)
);
package Tuple;
use FFI::Platypus::Record;
use overload
'""' => sub { shift->as_string },
bool => sub { 1 }, fallback => 1;
record_layout_1($ffi, qw(
u32 x
u32 y
));
sub as_string {
my $self = shift;
sprintf "[%d,%d]", $self->x, $self->y;
}
package main;
$ffi->type('record(Tuple)' => 'tuple_t');
$ffi->attach( flip_things_around => ['tuple_t'] => 'tuple_t' );
print flip_things_around(Tuple->new(x => 10, y => 20)), "\n";
```
### Execute
```
$ rustc tuple.rs
$ perl tuple.pl
[21,9]
```
### Notes
Rust's tuples do not have a standard representation that can be used
directly from Perl, but if your tuple contains only simple types you
can use the [Platypus Record class](https://metacpan.org/pod/FFI::Platypus::Record) and translate
in Rust between the tuple and the `struct`.
Because we are passing in and out the entire `struct`, not pointers
to a `struct` we don't have to worry about freeing them from Perl.
They just get allocated and freed on the stack.
(This example is based on one provided in the
[Rust FFI Omnibus](http://jakegoulding.com/rust-ffi-omnibus/tuples/))
## Objects
### Rust Source
```perl
use std::cell::RefCell;
use std::ffi::c_void;
use std::ffi::CStr;
use std::ffi::CString;
use std::os::raw::c_char;
struct Person {
name: String,
lucky_number: i32,
}
impl Person {
fn new(name: &str, lucky_number: i32) -> Person {
Person {
name: String::from(name),
lucky_number: lucky_number,
}
}
fn get_name(&self) -> String {
String::from(&self.name)
}
fn set_name(&mut self, new: &str) {
self.name = new.to_string();
}
fn get_lucky_number(&self) -> i32 {
self.lucky_number
}
}
type CPerson = c_void;
#[no_mangle]
pub extern "C" fn person_new(
_class: *const c_char,
name: *const c_char,
lucky_number: i32,
) -> *mut CPerson {
let name = unsafe { CStr::from_ptr(name) };
let name = name.to_string_lossy().into_owned();
Box::into_raw(Box::new(Person::new(&name, lucky_number))) as *mut CPerson
}
#[no_mangle]
pub extern "C" fn person_name(p: *mut CPerson) -> *const c_char {
thread_local!(
static KEEP: RefCell> = RefCell::new(None);
);
let p = unsafe { &*(p as *mut Person) };
let name = CString::new(p.get_name()).unwrap();
let ptr = name.as_ptr();
KEEP.with(|k| {
*k.borrow_mut() = Some(name);
});
ptr
}
#[no_mangle]
pub extern "C" fn person_rename(p: *mut CPerson, new: *const c_char) {
let new = unsafe { CStr::from_ptr(new) };
let p = unsafe { &mut *(p as *mut Person) };
if let Ok(new) = new.to_str() {
p.set_name(new);
}
}
#[no_mangle]
pub extern "C" fn person_lucky_number(p: *mut CPerson) -> i32 {
let p = unsafe { &*(p as *mut Person) };
p.get_lucky_number()
}
#[allow(non_snake_case)]
#[no_mangle]
pub extern "C" fn person_DESTROY(p: *mut CPerson) {
unsafe { Box::from_raw(p as *mut Person) };
}
#[cfg(test)]
mod test;
```
### Perl Source
Main class:
```perl
package Person;
use strict;
use warnings;
use FFI::Platypus 2.00;
our $VERSION = '2.00';
my $ffi = FFI::Platypus->new( api => 2, lang => 'Rust' );
# use the bundled code as a library
$ffi->bundle;
# use the person_ prefix
$ffi->mangler(sub {
my $symbol = shift;
return "person_$symbol";
});
# Create a custom type mapping for the person_t (C) and Person (perl)
# classes.
$ffi->type( 'object(Person)' => 'person_t' );
$ffi->attach( new => [ 'string', 'string', 'i32' ] => 'person_t' );
$ffi->attach( name => [ 'person_t' ] => 'string' );
$ffi->attach( rename => [ 'person_t', 'string' ] );
$ffi->attach( lucky_number => [ 'person_t' ] => 'i32' );
$ffi->attach( DESTROY => [ 'person_t' ] );
1;
```
Test:
```perl
use Test2::V0;
use Person;
my $plicease = Person->new("Graham Ollis", 42);
is $plicease->name, "Graham Ollis";
is $plicease->lucky_number, 42;
$plicease->rename("Graham THE Ollis");
is $plicease->name, "Graham THE Ollis";
done_testing;
```
### Execute
```
$ prove -lvm t/basic.t
t/basic.t ..
# Seeded srand with seed '20221023' from local date.
ok 1
ok 2
ok 3
1..3
ok
All tests successful.
Files=1, Tests=3, 0 wallclock secs ( 0.02 usr 0.00 sys + 0.19 cusr 0.05 csys = 0.26 CPU)
Result: PASS
```
### Notes
This example includes excerpts from a full `Person` dist which you can
find in the `examples/Person` directory of this distribution. You can
install it like a normal Perl distribution using [ExtUtils::MakeMaker](https://metacpan. ... ...
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