Module libffi::high

High layer providing automatic marshalling of Rust closures as C function pointers.

The main facility here is given by the structs ClosureN, ClosureMutN, and ClosureOnceN, for natural numbers N from 0 to 12 (as of now). These represent C closures of N arguments, which can be used to turn Rust lambdas (or in generally, anything that implements Fn or FnMut) into ordinary C function pointers. For example, a Rust value of type Fn(u32, u32) -> u64 can be turned into a closure of type Closure2<u32, u32, u64> using Closure2::new. Then a C function pointer of type extern "C" fn(u32, u32) -> u64 can be borrowed from the closure and passed to C.

The above usage case eliminates much of the boilerplate involved in creating a closure as compared to the middle and low layers, but at the price of flexibility. Some flexibility can be recovered by manually constructing and configuring a CIF (e.g., a Cif2) and then creating the closure with Closure2::new_with_cif.

See the call submodule for a simple interface to dynamic calls to C functions.

Examples

Here we use ClosureMut1, which is the type for creating mutable closures of one argument. We use it to turn a Rust lambda into a C function pointer.

use libffi::high::ClosureMut1;

let mut x = 0u64;
let mut f = |y: u32| { x += y as u64; x };

let closure = ClosureMut1::new(&mut f);
let counter = closure.code_ptr();

assert_eq!(5, counter(5));
assert_eq!(6, counter(1));
assert_eq!(8, counter(2));

Note that in the above example, counter is an ordinary C function pointer of type extern "C" fn(u64) -> u64.

Here’s an example using ClosureOnce3 to create a closure that owns a vector:

use libffi::high::ClosureOnce3;

let v = vec![1, 2, 3, 4, 5];
let mut f = move |x: usize, y: usize, z: usize| {
    v[x] + v[y] + v[z]
};

let closure = ClosureOnce3::new(f);
let call = closure.code_ptr();

assert_eq!(12, call(2, 3, 4));

Invoking the closure a second time will panic.

Re-exports

pub use types::Type;

pub use types::CType;

pub use call::*;

pub use arity0::*;

pub use arity1::*;

pub use arity2::*;

pub use arity3::*;

pub use arity4::*;

pub use arity5::*;

pub use arity6::*;

pub use arity7::*;

pub use arity8::*;

pub use arity9::*;

pub use arity10::*;

pub use arity11::*;

pub use arity12::*;

Modules

arity0	CIF and closure types organized by function arity.
arity1	CIF and closure types organized by function arity.
arity2	CIF and closure types organized by function arity.
arity3	CIF and closure types organized by function arity.
arity4	CIF and closure types organized by function arity.
arity5	CIF and closure types organized by function arity.
arity6	CIF and closure types organized by function arity.
arity7	CIF and closure types organized by function arity.
arity8	CIF and closure types organized by function arity.
arity9	CIF and closure types organized by function arity.
arity10	CIF and closure types organized by function arity.
arity11	CIF and closure types organized by function arity.
arity12	CIF and closure types organized by function arity.
call	Simple dynamic calls.
types	Representations of C types for the high layer.

Constants

ffi_abi_FFI_DEFAULT_ABI

Type Definitions

FfiAbi