Begin working towards Rust 2024 compatibility (#289)

This PR fixes up the easy issues with Rust 2024 compatibility and
enables the lint for it. However it also scopes out some allows for the
things that need some more work and focus. #288 is tracking them.

Changes in this PR:

- extern blocks are now unsafe
- `gen` is becoming a reserved keyword, rename variables
- mark unsafe attributes other than linkme's
- resolve the ambiguity of `fn poll` in VmbusSerialDriver

Author: smalis-msft

.github/scripts/add_unsafe_reviewers/add-unsafe-reviewers.py

@@ -15,7 +15,8 @@ def contains_unsafe(change) -> bool:
             return False
 
         with open(f'{repo_path}/{change.a_path}') as fd:
-            return 'unsafe ' in fd.read()
+            content = fd.read()
+            return 'unsafe ' in content or 'unsafe(' in content
 
     # Look for modified / added files
     repo = Repo(repo_path)

Cargo.toml

@@ -562,9 +562,17 @@ pbjson-build = { git = "https://github.com/jstarks/pbjson", branch = "aliases" }
 
 [workspace.lints.rust]
 # Lint groups need a priority lower than individual lints so they get applied first.
-future_incompatible = { level = "deny", priority = -1 }
-nonstandard_style = { level = "deny", priority = -1 }
-rust_2018_idioms = { level = "deny", priority = -1 }
+future_incompatible = { level = "deny", priority = -2 }
+nonstandard_style = { level = "deny", priority = -2 }
+rust_2018_idioms = { level = "deny", priority = -2 }
+
+rust-2024-compatibility = { level = "warn", priority = -1 }
+# TODO: Fix all of the below, https://github.com/microsoft/openvmm/issues/288
+edition_2024_expr_fragment_specifier = "allow"
+impl_trait_overcaptures = "allow"
+deprecated-safe-2024 = "allow"
+# Needed for linkme compatibility for now, https://github.com/dtolnay/linkme/issues/101
+unsafe-attr-outside-unsafe = "allow"
 
 unused_qualifications = "warn"
 

openhcl/build_info/src/lib.rs

@@ -62,8 +62,8 @@ impl BuildInfo {
 
 // UNSAFETY: link_section and export_name are considered unsafe.
 #[allow(unsafe_code)]
-#[link_section = ".build_info"]
-#[export_name = "BUILD_INFO"]
+#[unsafe(link_section = ".build_info")]
+#[unsafe(export_name = "BUILD_INFO")]
 static BUILD_INFO: BuildInfo = BuildInfo::new();
 
 pub fn get() -> &'static BuildInfo {

openhcl/minimal_rt/src/arch/aarch64/intrinsics.rs

@@ -5,7 +5,7 @@
 
 /// Hand rolled implementation of memcpy.
 #[cfg(minimal_rt)]
-#[no_mangle]
+#[unsafe(no_mangle)]
 unsafe extern "C" fn memcpy(mut dest: *mut u8, src: *const u8, len: usize) -> *mut u8 {
     // SAFETY: the caller guarantees the pointers and length are correct.
     unsafe {
@@ -31,7 +31,7 @@ unsafe extern "C" fn memcpy(mut dest: *mut u8, src: *const u8, len: usize) -> *m
 
 /// Hand rolled implementation of memset.
 #[cfg(minimal_rt)]
-#[no_mangle]
+#[unsafe(no_mangle)]
 unsafe extern "C" fn memset(mut ptr: *mut u8, val: i32, len: usize) -> *mut u8 {
     // SAFETY: the caller guarantees the pointer and length are correct.
     unsafe {

openhcl/minimal_rt/src/arch/x86_64/hypercall.rs

@@ -5,7 +5,7 @@
 //!
 //! The hypercall ABI for x64 is well documented in the TLFS.
 
-extern "C" {
+unsafe extern "C" {
     /// The hypercall page. The actual hypercall page must be mapped on top of
     /// this page before it is used.
     pub static mut HYPERCALL_PAGE: [u8; 4096];

openhcl/minimal_rt/src/arch/x86_64/intrinsics.rs

@@ -5,7 +5,7 @@
 
 /// Hand rolled implementation of memset.
 #[cfg(minimal_rt)]
-#[no_mangle]
+#[unsafe(no_mangle)]
 unsafe extern "C" fn memset(mut ptr: *mut u8, val: i32, len: usize) -> *mut u8 {
     // SAFETY: The caller guarantees that the pointer and length are correct.
     unsafe {
@@ -22,7 +22,7 @@ unsafe extern "C" fn memset(mut ptr: *mut u8, val: i32, len: usize) -> *mut u8 {
 
 /// Hand rolled implementation of memcpy.
 #[cfg(minimal_rt)]
-#[no_mangle]
+#[unsafe(no_mangle)]
 unsafe extern "C" fn memcpy(mut dest: *mut u8, src: *const u8, len: usize) -> *mut u8 {
     // SAFETY: The caller guarantees that the pointers and length are correct.
     unsafe {

openhcl/minimal_rt/src/rt.rs

@@ -19,12 +19,12 @@ mod instead_of_builtins {
         }
     }
 
-    extern "C" {
+    unsafe extern "C" {
         fn memcpy(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
     }
 
     /// Implementation cribbed from compiler_builtins.
-    #[no_mangle]
+    #[unsafe(no_mangle)]
     unsafe extern "C" fn memmove(dest: *mut u8, src: *const u8, n: usize) -> *mut u8 {
         let delta = (dest as usize).wrapping_sub(src as usize);
         if delta >= n {
@@ -47,7 +47,7 @@ mod instead_of_builtins {
     /// This implementation is cribbed from compiler_builtins. It would be nice to
     /// use those implementation for all the above functions, but those require
     /// nightly as these are not yet stabilized.
-    #[no_mangle]
+    #[unsafe(no_mangle)]
     unsafe extern "C" fn bcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
         // SAFETY: The caller guarantees that the pointers and length are correct.
         unsafe {

openhcl/openhcl_boot/src/main.rs

@@ -270,7 +270,7 @@ struct Fdt {
 /// where the shim is loaded. Return a ShimParams structure based on the raw
 /// offset based RawShimParams.
 fn shim_parameters(shim_params_raw_offset: isize) -> ShimParams {
-    extern "C" {
+    unsafe extern "C" {
         static __ehdr_start: u8;
     }
 

openhcl/sidecar/src/arch/x86_64/init.rs

@@ -55,7 +55,7 @@ use x86defs::IdtEntry64;
 use x86defs::Pte;
 use zerocopy::FromZeroes;
 
-extern "C" {
+unsafe extern "C" {
     static IMAGE_PDE: Pte;
     fn irq_entry();
     fn exc_gpf();

openhcl/sidecar/src/arch/x86_64/mod.rs

@@ -38,7 +38,7 @@ mod addr_space {
 
     const PAGE_SIZE: u64 = 0x1000;
 
-    extern "C" {
+    unsafe extern "C" {
         static __ehdr_start: u8;
     }
 

support/openssl_crypto_only/src/lib.rs

@@ -13,7 +13,7 @@
 use core::ffi::c_int;
 use core::ffi::c_void;
 
-extern "C" {
+unsafe extern "C" {
     #[doc(hidden)]
     pub fn OPENSSL_init_crypto(opts: u64, settings: *const c_void) -> c_int;
 }
@@ -33,7 +33,7 @@ macro_rules! openssl_crypto_only {
         /// # Safety
         ///
         /// The caller must call as documented for `OPENSSL_init_ssl`.
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         unsafe extern "C" fn OPENSSL_init_ssl(
             opts: u64,
             settings: *const ::core::ffi::c_void,

support/openssl_kdf/src/sys/evp.rs

@@ -19,7 +19,7 @@ pub enum KDF {}
 
 pub enum KDF_CTX {}
 
-extern "C" {
+unsafe extern "C" {
     pub fn EVP_MD_get0_name(md: *const EVP_MD) -> *const c_char;
 }
 
@@ -31,7 +31,7 @@ pub const OSSL_PARAM_OCTET_STRING: c_uchar = 5;
 pub const OSSL_PARAM_UTF8_PTR: c_uchar = 6;
 pub const OSSL_PARAM_OCTET_PTR: c_uchar = 7;
 
-extern "C" {
+unsafe extern "C" {
     pub fn EVP_KDF_fetch(
         libctx: *mut OSSL_LIB_CTX,
         algorithm: *const c_char,

support/openssl_kdf/src/sys/params.rs

@@ -18,7 +18,7 @@ use libc::time_t;
 use openssl_sys::BIGNUM;
 use std::ffi::CStr;
 
-extern "C" {
+unsafe extern "C" {
     pub fn OSSL_PARAM_get_int(p: *const OSSL_PARAM, val: *mut c_int) -> c_int;
     pub fn OSSL_PARAM_get_uint(p: *const OSSL_PARAM, val: *mut c_uint) -> c_int;
     pub fn OSSL_PARAM_get_long(p: *const OSSL_PARAM, val: *mut c_long) -> c_int;

support/pal/src/windows/alpc.rs

@@ -57,7 +57,7 @@ mod ntlpcapi {
     pub const OB_ALL_OBJECT_TYPE_CODES: u32 = 0x00000ffd;
 
     // This is defined incorrectly in ntapi 0.3.6.
-    extern "C" {
+    unsafe extern "C" {
         pub fn AlpcInitializeMessageAttribute(
             AttributeFlags: u32,
             Buffer: PALPC_MESSAGE_ATTRIBUTES,

support/pal/src/windows/security.rs

@@ -318,7 +318,7 @@ impl SecurityDescriptor {
 }
 
 #[link(name = "api-ms-win-security-base-private-l1-1-1")]
-extern "C" {
+unsafe extern "C" {
     fn CreateAppContainerToken(
         token: HANDLE,
         caps: LPSECURITY_CAPABILITIES,

support/sparse_mmap/src/lib.rs

@@ -47,7 +47,7 @@ pub fn initialize_try_copy() {
     }
 }
 
-extern "C" {
+unsafe extern "C" {
     #[cfg(unix)]
     fn install_signal_handlers() -> i32;
 

support/win_prng_support/src/lib.rs

@@ -25,20 +25,20 @@ macro_rules! use_win10_prng_apis {
         $($crate::use_win10_prng_apis!(@x $lib);)*
     };
     (@x advapi32) => {
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub unsafe extern "system" fn SystemFunction036(data: *mut u8, len: u32) -> u8 {
             // SAFETY: passing through guarantees.
             unsafe { $crate::private::SystemFunction036(data, len) }
         }
 
         /// If a call to SystemFunction036 is marked as a dllimport, then it may be an indirect call
         /// through __imp_SystemFunction036 instead.
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub static __imp_SystemFunction036: unsafe extern "system" fn(*mut u8, u32) -> u8 =
             SystemFunction036;
     };
     (@x bcrypt) => {
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub unsafe extern "system" fn BCryptOpenAlgorithmProvider(
             handle: *mut ::core::ffi::c_void,
             psz_alg_id: *mut u16,
@@ -56,7 +56,7 @@ macro_rules! use_win10_prng_apis {
             }
         }
 
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub unsafe extern "system" fn BCryptCloseAlgorithmProvider(
             handle: *mut ::core::ffi::c_void,
             flags: u32,
@@ -65,7 +65,7 @@ macro_rules! use_win10_prng_apis {
             unsafe { $crate::private::BCryptCloseAlgorithmProvider(handle, flags) }
         }
 
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub unsafe extern "system" fn BCryptGenRandom(
             algorithm: usize,
             data: *mut u8,
@@ -78,23 +78,23 @@ macro_rules! use_win10_prng_apis {
 
         /// If a call to BCryptGenRandom is marked as a dllimport, then it may be an indirect call
         /// through __imp_BCryptGenRandom instead.
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub static __imp_BCryptGenRandom: unsafe extern "system" fn(
             usize,
             *mut u8,
             u32,
             u32,
         ) -> u32 = BCryptGenRandom;
 
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub static __imp_BCryptOpenAlgorithmProvider: unsafe extern "system" fn(
             *mut ::core::ffi::c_void,
             *mut u16,
             *mut u16,
             u32,
         ) -> u32 = BCryptOpenAlgorithmProvider;
 
-        #[no_mangle]
+        #[unsafe(no_mangle)]
         pub static __imp_BCryptCloseAlgorithmProvider: unsafe extern "system" fn(
             *mut ::core::ffi::c_void,
             u32,
@@ -115,7 +115,7 @@ pub mod private {
     const BCRYPT_MAGIC_ALGORITHM_HANDLE: usize = 0x1234abcd;
 
     #[link(name = "ext-ms-win-cng-rng-l1-1-0")]
-    extern "C" {
+    unsafe extern "C" {
         /// The lowest-level PRNG API in Windows.
         fn ProcessPrng(data: *mut u8, len: usize) -> u32;
     }