ring/digest/sha2/
ffi.rs

1// Copyright 2024 Brian Smith.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15use super::CHAINING_WORDS;
16use crate::polyfill::slice::AsChunks;
17use core::num::{NonZeroUsize, Wrapping};
18
19/// `unsafe { T => f }` means it is safe to call `f` iff we can construct
20/// a value of type `T`.
21macro_rules! sha2_ffi {
22    ( $U:ty, $BLOCK_LEN:expr, unsafe { $Cpu:ty => $f:ident },
23      $state:expr, $data:expr, $cpu:expr $(,)? ) => {{
24        prefixed_extern! {
25            fn $f(
26                state: *mut [core::num::Wrapping<$U>; crate::digest::sha2::CHAINING_WORDS],
27                data: *const [u8; $BLOCK_LEN],
28                num: crate::c::NonZero_size_t);
29        }
30        // SAFETY: The user asserts that $f has the signature above and is safe
31        // to call if additionally we have a value of type `$Cpu`, which we do.
32        unsafe {
33            crate::digest::sha2::ffi::sha2_ffi::<$U, $Cpu, { $BLOCK_LEN }>($state, $data, $cpu, $f)
34        }
35    }};
36}
37
38macro_rules! sha2_32_ffi {
39    ( unsafe { $Cpu:ty => $f:ident }, $state:expr, $data:expr, $cpu:expr $(,)? ) => {
40        sha2_ffi!(u32, crate::digest::sha2::SHA256_BLOCK_LEN.into(),
41                  unsafe { $Cpu => $f }, $state, $data, $cpu)
42    }
43}
44
45macro_rules! sha2_64_ffi {
46    ( unsafe { $Cpu:ty => $f:ident }, $state:expr, $data:expr, $cpu:expr $(,)? ) => {
47        sha2_ffi!(u64, SHA512_BLOCK_LEN.into(), unsafe { $Cpu => $f }, $state, $data, $cpu)
48    }
49}
50
51pub(super) unsafe fn sha2_ffi<U, Cpu, const BLOCK_LEN: usize>(
52    state: &mut [Wrapping<U>; CHAINING_WORDS],
53    data: AsChunks<u8, BLOCK_LEN>,
54    cpu: Cpu,
55    f: unsafe extern "C" fn(
56        *mut [Wrapping<U>; CHAINING_WORDS],
57        *const [u8; BLOCK_LEN],
58        crate::c::NonZero_size_t,
59    ),
60) {
61    if let Some(blocks) = NonZeroUsize::new(data.len()) {
62        let data = data.as_ptr();
63        let _: Cpu = cpu;
64        // SAFETY:
65        //   * `blocks` is non-zero.
66        //   * `data` is non-NULL and points to `blocks` blocks.
67        //   * The caller asserted that `f` meets this contract if we have
68        //     an instance of `Cpu`.
69        unsafe { f(state, data, blocks) }
70    }
71}
ring/digest/sha2/ffi.rs

ring/digest/sha2/
ffi.rs
