Struct libffi::low::CodePtr

#[repr(C)]
pub struct CodePtr(pub *mut c_void);

Wraps a function pointer of unknown type.

This is used to make the API a bit easier to understand, and as a simple type lint. As a repr(C) struct of one element, it should be safe to transmute between CodePtr and *mut c_void, or between collections thereof.

Methods

impl CodePtr

pub fn from_fun(fun: unsafe extern "C" fn()) -> Self

Initializes a code pointer from a function pointer.

This is useful mainly for talking to C APIs that take untyped callbacks specified in the API as having type void(*)().

pub fn from_ptr(fun: *const c_void) -> Self

Initializes a code pointer from a void pointer.

This is the other common type used in APIs (or at least in libffi) for untyped callback arguments.

pub fn as_fun(&self) -> &unsafe extern "C" fn()

Gets the code pointer typed as a C function pointer.

This is useful mainly for talking to C APIs that take untyped callbacks specified in the API as having type void(*)().

Safety

There is no checking that the returned type reflects the actual parameter and return types of the function. Unless the C function actually has type void(*)(), it will need to be cast before it is called.

pub unsafe fn as_safe_fun(&self) -> &extern "C" fn()

Gets the code pointer typed as a “safe” C function pointer.

This is useful mainly for talking to C APIs that take untyped callbacks specified in the API as having type void(*)().

Safety

There isn’t necessarily anything actually safe about the resulting function pointer—it’s up to the caller to know what they’re doing within the unsafety boundary, or undefined behavior may result. In particular, there is no checking that the returned type reflects the actual parameter and return types of the function. Unless the C function actually has type void(*)(), it will need to be cast before it is called.

pub fn as_ptr(self) -> *const c_void

Gets the code pointer typed as a const void*.

This is the other common type used in APIs (or at least in libffi) for untyped callback arguments.

pub fn as_mut_ptr(self) -> *mut c_void

Gets the code pointer typed as a void*.

This is the other common type used in APIs (or at least in libffi) for untyped callback arguments.

Trait Implementations

impl Clone for CodePtr

fn clone(&self) -> CodePtr

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for CodePtr

impl Debug for CodePtr

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Hash for CodePtr

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].