types.rs

#![allow(non_camel_case_types)]
use core::{fmt, mem};

pub type c_int = i32;
pub type c_uchar = u8;
pub type c_uint = u32;
pub type size_t = usize;

/// This might not match C's `c_char` exactly.
/// The way we use it makes it fine either way but this type shouldn't be used outside of the library.
pub type c_char = i8;

/// This is an exact copy of https://doc.rust-lang.org/core/ffi/enum.c_void.html
/// It should be Equivalent to C's void type when used as a pointer.
///
/// We can replace this with `core::ffi::c_void` once we update the rustc version to >=1.30.0.
#[repr(u8)]
pub enum c_void {
    #[doc(hidden)] __variant1,
    #[doc(hidden)] __variant2,
}

impl fmt::Debug for c_void {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.pad("c_void")
    }
}

/// A type that is as aligned as the biggest alignment for fundamental types in C
/// since C11 that means as aligned as `max_align_t` is.
/// the exact size/alignment is unspecified.
// 16 matches is as big as the biggest alignment in any arch that rust currently supports https://github.com/rust-lang/rust/blob/2c31b45ae878b821975c4ebd94cc1e49f6073fd0/library/std/src/sys_common/alloc.rs
#[repr(align(16))]
#[derive(Default, Copy, Clone)]
pub struct AlignedType([u8; 16]);

impl AlignedType {
    pub fn zeroed() -> Self {
        AlignedType([0u8; 16])
    }
}

pub(crate) const ALIGN_TO: usize = mem::align_of::<AlignedType>();


#[cfg(test)]
mod tests {
    extern crate libc;
    use std::os::raw;
    use std::mem;
    use std::any::TypeId;
    use {types, AlignedType};

    #[test]
    fn verify_types() {
        assert_eq!(TypeId::of::<types::c_int>(), TypeId::of::<raw::c_int>());
        assert_eq!(TypeId::of::<types::c_uchar>(), TypeId::of::<raw::c_uchar>());
        assert_eq!(TypeId::of::<types::c_uint>(), TypeId::of::<raw::c_uint>());
        assert_eq!(TypeId::of::<types::c_char>(), TypeId::of::<raw::c_char>());

        assert!(mem::align_of::<AlignedType>() >= mem::align_of::<self::libc::max_align_t>());
    }
}


#[doc(hidden)]
#[cfg(target_arch = "wasm32")]
pub fn sanity_checks_for_wasm() {
    use std::mem::{size_of, align_of};
    extern "C" {
        pub static WASM32_INT_SIZE: c_uchar;
        pub static WASM32_INT_ALIGN: c_uchar;

        pub static WASM32_UNSIGNED_INT_SIZE: c_uchar;
        pub static WASM32_UNSIGNED_INT_ALIGN: c_uchar;

        pub static WASM32_SIZE_T_SIZE: c_uchar;
        pub static WASM32_SIZE_T_ALIGN: c_uchar;

        pub static WASM32_UNSIGNED_CHAR_SIZE: c_uchar;
        pub static WASM32_UNSIGNED_CHAR_ALIGN: c_uchar;

        pub static WASM32_PTR_SIZE: c_uchar;
        pub static WASM32_PTR_ALIGN: c_uchar;
    }
    unsafe {
        assert_eq!(size_of::<c_int>(), WASM32_INT_SIZE as usize);
        assert_eq!(align_of::<c_int>(), WASM32_INT_ALIGN as usize);

        assert_eq!(size_of::<c_uint>(), WASM32_UNSIGNED_INT_SIZE as usize);
        assert_eq!(align_of::<c_uint>(), WASM32_UNSIGNED_INT_ALIGN as usize);

        assert_eq!(size_of::<size_t>(), WASM32_SIZE_T_SIZE as usize);
        assert_eq!(align_of::<size_t>(), WASM32_SIZE_T_ALIGN as usize);

        assert_eq!(size_of::<c_uchar>(), WASM32_UNSIGNED_CHAR_SIZE as usize);
        assert_eq!(align_of::<c_uchar>(), WASM32_UNSIGNED_CHAR_ALIGN as usize);

        assert_eq!(size_of::<*const ()>(), WASM32_PTR_SIZE as usize);
        assert_eq!(align_of::<*const ()>(), WASM32_PTR_ALIGN as usize);
    }
}