Attribute Macro safer_ffi::ffi_export

#[ffi_export]

Export a function to be callable by C.

Example

use ::safer_ffi::prelude::ffi_export;

#[ffi_export]
/// Add two integers together.
fn add (x: i32, y: i32) -> i32
{
    x + y
}

• ensures that the generated headers will include the following definition:

  #include <stdint.h>
  
  /* \brief
   * Add two integers together.
   */
  int32_t add (int32_t x, int32_t y);
  

• exports an add symbol pointing to the C-ABI compatible int32_t (*)(int32_t x, int32_t y) function.

  (The crate type needs to be cdylib or staticlib for this to work, and, of course, the C compiler invocation needs to include -L path/to/the/compiled/library -l name_of_your_crate)

  • when in doubt, use staticlib.

ReprC

You can use any Rust types in the singature of an #[ffi_export]- function, provided each of the types involved in the signature is ReprC.

Otherwise the layout of the involved types in the C world is undefined, which #[ffi_export] will detect, leading to a compilation error.

To have custom structs implement ReprC, it suffices to annotate the struct definitions with the #[derive_ReprC] (on top of the obviously required #[repr(C)]).