Bump MSRV to 1.64.

* Use core::ffi::{c_int, c_uint} and remove our polyfills,
  eliminating libc as a dev-dependency.
* Somplify CI configuration for symbol prefixing since 1.64.0 has
  llvm-tools-preview.
* Use `core::ffi::CStr` in aarch64-apple-* feature detection.

.github/workflows/ci.yml

@@ -169,7 +169,7 @@ jobs:
         rust_channel:
           - stable
           # Keep in sync with Cargo.toml and similar `rust_channel` sections.
-          - 1.63.0 # MSRV
+          - 1.64.0 # MSRV
           # TODO: Move these to a daily/pre-release job.
           # - nightly
           # - beta
@@ -305,12 +305,10 @@ jobs:
       # Check that all the needed symbol renaming was done.
       # TODO: Do this check on Windows too.
 
-      - if: ${{ (matrix.target != 'aarch64-apple-ios' || matrix.rust_channel != '1.63.0') &&
-                !contains(matrix.host_os, 'windows') }}
+      - if: ${{ !contains(matrix.host_os, 'windows') }}
         run: rustup toolchain install --component=llvm-tools-preview ${{ matrix.rust_channel }}
 
-      - if: ${{ (matrix.target != 'aarch64-apple-ios' || matrix.rust_channel != '1.63.0') &&
-                !contains(matrix.host_os, 'windows') }}
+      - if: ${{ !contains(matrix.host_os, 'windows') }}
         run: mk/check-symbol-prefixes.sh +${{ matrix.rust_channel }} --target=${{ matrix.target }}
 
   test-bench:
@@ -387,7 +385,7 @@ jobs:
           - stable
           - nightly
           # Keep in sync with Cargo.toml and similar `rust_channel` sections.
-          - 1.63.0 # MSRV
+          - 1.64.0 # MSRV
 
         include:
           - target: aarch64-unknown-linux-musl
@@ -435,12 +433,9 @@ jobs:
       # Check that all the needed symbol renaming was done.
       # TODO: Do this check on Windows too.
 
-      - if: ${{ (matrix.target != 'aarch64-apple-ios' || matrix.rust_channel != '1.63.0') &&
-          !contains(matrix.host_os, 'windows') }}
-        run: rustup toolchain install --component=llvm-tools-preview ${{ matrix.rust_channel }}
+      - run: rustup toolchain install --component=llvm-tools-preview ${{ matrix.rust_channel }}
 
-      - if: ${{ (matrix.target != 'aarch64-apple-ios' || matrix.rust_channel != '1.63.0') &&
-          !contains(matrix.host_os, 'windows') }}
+      - if: ${{ !contains(matrix.host_os, 'windows') }}
         run: mk/check-symbol-prefixes.sh +${{ matrix.rust_channel }} --target=${{ matrix.target }}
 
   # The wasm32-unknown-unknown targets have a different set of feature sets and
@@ -498,7 +493,6 @@ jobs:
           ${{ matrix.webdriver }} mk/cargo.sh +${{ matrix.rust_channel }} test -vv --target=${{ matrix.target }} ${{ matrix.features }} ${{ matrix.mode }}
 
       # Check that all the needed symbol renaming was done.
-      # TODO: Do this check on Windows too.
       - run: rustup toolchain install --component=llvm-tools-preview ${{ matrix.rust_channel }}
       - run: mk/check-symbol-prefixes.sh +${{ matrix.rust_channel }} --target=${{ matrix.target }}
 

Cargo.toml

@@ -11,7 +11,7 @@ repository = "https://github.com/briansmith/ring"
 
 # Keep in sync with .github/workflows/ci.yml ("MSRV") and see the MSRV note
 # in cpu/arm.rs
-rust-version = "1.63.0"
+rust-version = "1.64.0"
 
 # Keep in sync with `links` below.
 version = "0.17.8"
@@ -171,9 +171,6 @@ windows-sys = { version = "0.52", features = ["Win32_Foundation", "Win32_System_
 [target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dev-dependencies]
 wasm-bindgen-test = { version = "0.3.37", default-features = false }
 
-[target.'cfg(any(unix, windows, target_os = "wasi"))'.dev-dependencies]
-libc = { version = "0.2.148", default-features = false }
-
 [build-dependencies]
 cc = { version = "1.0.83", default-features = false }
 

src/aead/aes.rs

@@ -18,7 +18,11 @@ use crate::{
     c, constant_time, cpu, error,
     polyfill::{self, slice},
 };
-use core::{num::NonZeroUsize, ops::RangeFrom};
+use core::{
+    ffi::{c_int, c_uint},
+    num::NonZeroUsize,
+    ops::RangeFrom,
+};
 
 #[derive(Clone)]
 pub(super) struct Key {
@@ -38,15 +42,15 @@ pub(super) struct Key {
 macro_rules! set_encrypt_key {
     ( $name:ident, $key_bytes:expr, $key:expr, $cpu_features:expr ) => {{
         prefixed_extern! {
-            fn $name(user_key: *const u8, bits: BitLength<c::int>, key: *mut AES_KEY) -> c::int;
+            fn $name(user_key: *const u8, bits: BitLength<c_int>, key: *mut AES_KEY) -> c_int;
         }
         set_encrypt_key($name, $key_bytes, $key, $cpu_features)
     }};
 }
 
 #[inline]
 unsafe fn set_encrypt_key(
-    f: unsafe extern "C" fn(*const u8, BitLength<c::int>, *mut AES_KEY) -> c::int,
+    f: unsafe extern "C" fn(*const u8, BitLength<c_int>, *mut AES_KEY) -> c_int,
     bytes: KeyBytes<'_>,
     key: &mut AES_KEY,
     _cpu_features: cpu::Features,
@@ -363,7 +367,7 @@ impl Key {
 #[derive(Clone)]
 pub(super) struct AES_KEY {
     pub rd_key: [u32; 4 * (MAX_ROUNDS + 1)],
-    pub rounds: c::uint,
+    pub rounds: c_uint,
 }
 
 // Keep this in sync with `AES_MAXNR` in aes.h.

src/bssl.rs

@@ -12,15 +12,16 @@
 // OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
-use crate::{c, error};
+use crate::error;
+use core::ffi::c_int;
 
 /// An `int` returned from a foreign function containing **1** if the function
 /// was successful or **0** if an error occurred. This is the convention used by
 /// C code in `ring`.
 #[derive(Clone, Copy, Debug)]
 #[must_use]
 #[repr(transparent)]
-pub struct Result(c::int);
+pub struct Result(c_int);
 
 impl From<Result> for core::result::Result<(), error::Unspecified> {
     fn from(ret: Result) -> Self {
@@ -37,12 +38,12 @@ impl From<Result> for core::result::Result<(), error::Unspecified> {
 #[cfg(test)]
 mod tests {
     mod result {
-        use crate::{bssl, c};
-        use core::mem;
+        use crate::bssl;
+        use core::{ffi::c_int, mem};
 
         #[test]
         fn size_and_alignment() {
-            type Underlying = c::int;
+            type Underlying = c_int;
             assert_eq!(mem::size_of::<bssl::Result>(), mem::size_of::<Underlying>());
             assert_eq!(
                 mem::align_of::<bssl::Result>(),

src/c.rs

@@ -19,41 +19,8 @@
 //! are all uniformly defined on the platforms we care about. This will
 //! probably change if/when we support 16-bit platforms or platforms where
 //! `usize` and `uintptr_t` are different sizes.
-//!
-//! TODO(MSRV-1.64): Use `core::ffi::{c_int, c_uint}`, remove the libc
-//! compatibility testing, and remove the libc dev-dependency.
-
-// Keep in sync with the checks in base.h that verify these assumptions.
-
-#![allow(dead_code)]
 
 use core::num::NonZeroUsize;
 
-pub(crate) type int = i32;
-pub(crate) type uint = u32;
 pub(crate) type size_t = usize;
 pub(crate) type NonZero_size_t = NonZeroUsize;
-
-#[cfg(all(test, any(unix, windows)))]
-mod tests {
-    use crate::c;
-
-    #[test]
-    fn test_libc_compatible() {
-        {
-            let x: c::int = 1;
-            let _x: libc::c_int = x;
-        }
-
-        {
-            let x: c::uint = 1;
-            let _x: libc::c_uint = x;
-        }
-
-        {
-            let x: c::size_t = 1;
-            let _x: libc::size_t = x;
-            let _x: usize = x;
-        }
-    }
-}

src/constant_time.rs

@@ -15,6 +15,7 @@
 //! Constant-time operations.
 
 use crate::{c, error};
+use core::ffi::c_int;
 
 /// Returns `Ok(())` if `a == b` and `Err(error::Unspecified)` otherwise.
 /// The comparison of `a` and `b` is done in constant time with respect to the
@@ -32,7 +33,7 @@ pub fn verify_slices_are_equal(a: &[u8], b: &[u8]) -> Result<(), error::Unspecif
 }
 
 prefixed_extern! {
-    fn CRYPTO_memcmp(a: *const u8, b: *const u8, len: c::size_t) -> c::int;
+    fn CRYPTO_memcmp(a: *const u8, b: *const u8, len: c::size_t) -> c_int;
 }
 
 pub(crate) fn xor<const N: usize>(mut a: [u8; N], b: [u8; N]) -> [u8; N] {

src/cpu/arm/darwin.rs

@@ -14,6 +14,7 @@
 
 use super::{AES, ARMCAP_STATIC, NEON, PMULL, SHA256, SHA512};
 use crate::polyfill::{cstr, unwrap_const};
+use core::ffi::{c_int, c_void, CStr};
 
 // ```
 // $ rustc +1.61.0 --print cfg --target=aarch64-apple-ios | grep -E "neon|aes|sha|pmull"
@@ -51,10 +52,9 @@ const _AARCH64_APPLE_DARWIN_TARGETS_EXPECTED_FEATURES: () =
     assert!(ARMCAP_STATIC == MIN_STATIC_FEATURES);
 
 pub fn detect_features() -> u32 {
-    fn detect_feature(name: cstr::Ref) -> bool {
+    fn detect_feature(name: &CStr) -> bool {
         use crate::polyfill;
         use core::mem;
-        use libc::{c_int, c_void};
 
         let mut value: c_int = 0;
         let mut len = mem::size_of_val(&value);
@@ -80,9 +80,8 @@ pub fn detect_features() -> u32 {
     let mut features = 0;
 
     // TODO(MSRV 1.77): Use c"..." literal.
-    const SHA512_NAME: cstr::Ref = unwrap_const(cstr::const_from_bytes_with_nul(
-        b"hw.optional.armv8_2_sha512\0",
-    ));
+    const SHA512_NAME: &CStr =
+        unwrap_const(cstr::from_bytes_with_nul(b"hw.optional.armv8_2_sha512\0"));
     if detect_feature(SHA512_NAME) {
         features |= SHA512.mask;
     }

src/ec/curve25519/ops.rs

@@ -17,10 +17,10 @@
 
 pub use super::scalar::{MaskedScalar, Scalar, SCALAR_LEN};
 use crate::{
-    bssl, c, cpu, error,
+    bssl, cpu, error,
     limb::{Limb, LIMB_BITS},
 };
-use core::marker::PhantomData;
+use core::{ffi::c_int, marker::PhantomData};
 
 // Elem<T>` is `fe` in curve25519/internal.h.
 // Elem<L> is `fe_loose` in curve25519/internal.h.
@@ -82,7 +82,7 @@ impl ExtPoint {
             t: Elem::zero(),
         };
         prefixed_extern! {
-            fn x25519_ge_scalarmult_base(h: &mut ExtPoint, a: &Scalar, has_fe25519_adx: c::int);
+            fn x25519_ge_scalarmult_base(h: &mut ExtPoint, a: &Scalar, has_fe25519_adx: c_int);
         }
         unsafe {
             x25519_ge_scalarmult_base(&mut r, scalar, has_fe25519_adx(cpu).into());

src/ec/curve25519/x25519.rs

@@ -15,7 +15,8 @@
 //! X25519 Key agreement.
 
 use super::{ops, scalar::SCALAR_LEN};
-use crate::{agreement, c, constant_time, cpu, ec, error, rand};
+use crate::{agreement, constant_time, cpu, ec, error, rand};
+use core::ffi;
 
 static CURVE25519: ec::Curve = ec::Curve {
     public_key_len: PUBLIC_KEY_LEN,
@@ -79,7 +80,7 @@ fn x25519_public_from_private(
         fn x25519_public_from_private_generic_masked(
             public_key_out: &mut PublicKey,
             private_key: &PrivateKey,
-            use_adx: c::int,
+            use_adx: ffi::c_int,
         );
     }
     unsafe {

src/polyfill/cstr.rs

@@ -12,39 +12,15 @@
 // OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 // CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
-//! Work around lack of `core::ffi::CStr` prior to Rust 1.64, and the lack of
-//! `const fn` support for `CStr` in later versions.
+//! Work around lack of `const fn` support for `CStr`.
 
 #![cfg(all(target_arch = "aarch64", target_vendor = "apple"))]
 
-// TODO(MSRV 1.64): Use `core::ffi::c_chra`.
-use libc::c_char;
-
-// TODO(MSRV 1.64): Replace with `&core::ffi::CStr`.
-pub struct Ref(&'static [u8]);
-
-impl Ref {
-    #[inline(always)]
-    pub fn as_ptr(&self) -> *const c_char {
-        const _SAME_ALIGNMENT: () =
-            assert!(core::mem::align_of::<u8>() == core::mem::align_of::<c_char>());
-        const _SAME_SIZE: () =
-            assert!(core::mem::size_of::<u8>() == core::mem::size_of::<c_char>());
-
-        // It is safe to cast a `*const u8` to a `const c_char` as they are the
-        // same size and alignment.
-        self.0.as_ptr().cast()
-    }
-
-    // SAFETY: Same as `CStr::from_bytes_with_nul_unchecked`.
-    const unsafe fn from_bytes_with_nul_unchecked(value: &'static [u8]) -> Self {
-        Self(value)
-    }
-}
+use core::ffi::CStr;
 
 // TODO(MSRV 1.72): Replace with `CStr::from_bytes_with_nul`.
 #[inline(always)]
-pub const fn const_from_bytes_with_nul(value: &'static [u8]) -> Option<Ref> {
+pub const fn const_from_bytes_with_nul(value: &'static [u8]) -> Option<&'static CStr> {
     const fn const_contains(mut value: &[u8], needle: &u8) -> bool {
         while let [head, tail @ ..] = value {
             if *head == *needle {
@@ -61,8 +37,7 @@ pub const fn const_from_bytes_with_nul(value: &'static [u8]) -> Option<Ref> {
             // SAFETY:
             //   * `value` is nul-terminated according to the slice pattern.
             //   * `value` doesn't contain any interior null, by the guard.
-            // TODO(MSRV 1.64): Use `CStr::from_bytes_with_nul_unchecked`
-            Some(unsafe { Ref::from_bytes_with_nul_unchecked(value) })
+            Some(unsafe { CStr::from_bytes_with_nul_unchecked(value) })
         }
         _ => None,
     }