Fixes needed by io_uring. (#873)

* Fixes needed by io_uring.

 - Have the `io_uring` module export more types used in opcode entries.
 - Define a conversion from `SocketAddr` to `SocketAddrAny`.
 - Add comments to the `fadvise` implementation.

* Pin regex to 1.9 in Rust 1.63 builds.

* Make more `Epoll` types available to io_uring too.

This enables most of the epoll module without needing "alloc". It
doesn't enable `epoll_wait`, because that needs `Vec`, but this
does potentially open up a path to having a non-allocating opetion
for waiting on an epoll.

.github/workflows/main.yml

@@ -52,6 +52,7 @@ jobs:
       if: matrix.rust == '1.63'
       run: |
         cargo update --package=dashmap --precise 5.4.0
+        cargo update --package=regex --precise=1.9.0
 
     - run: >
         rustup target add
@@ -481,6 +482,7 @@ jobs:
       if: matrix.rust == '1.63'
       run: |
         cargo update --package=dashmap --precise 5.4.0
+        cargo update --package=regex --precise=1.9.0
 
     - run: |
         cargo test --verbose --features=all-apis --release --workspace -- --nocapture

Cargo.toml

@@ -135,7 +135,7 @@ event = []
 fs = []
 
 # Enable `rustix::io_uring::*` (on platforms that support it).
-io_uring = ["fs", "net", "linux-raw-sys/io_uring"]
+io_uring = ["event", "fs", "net", "linux-raw-sys/io_uring"]
 
 # Enable `rustix::mount::*`.
 mount = []

src/backend/libc/event/epoll.rs

@@ -74,10 +74,13 @@
 //! ```
 
 use crate::backend::c;
-use crate::backend::conv::{ret, ret_owned_fd, ret_u32};
+#[cfg(feature = "alloc")]
+use crate::backend::conv::ret_u32;
+use crate::backend::conv::{ret, ret_owned_fd};
 use crate::fd::{AsFd, AsRawFd, OwnedFd};
 use crate::io;
 use crate::utils::as_mut_ptr;
+#[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 use bitflags::bitflags;
 use core::ffi::c_void;
@@ -257,6 +260,8 @@ pub fn delete(epoll: impl AsFd, source: impl AsFd) -> io::Result<()> {
 ///
 /// For each event of interest, an element is written to `events`. On
 /// success, this returns the number of written elements.
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
 pub fn wait(epoll: impl AsFd, event_list: &mut EventVec, timeout: c::c_int) -> io::Result<()> {
     // SAFETY: We're calling `epoll_wait` via FFI and we know how it
     // behaves.
@@ -395,10 +400,12 @@ struct SixtyFourBitPointer {
 }
 
 /// A vector of `Event`s, plus context for interpreting them.
+#[cfg(feature = "alloc")]
 pub struct EventVec {
     events: Vec<Event>,
 }
 
+#[cfg(feature = "alloc")]
 impl EventVec {
     /// Constructs an `EventVec` from raw pointer, length, and capacity.
     ///
@@ -473,6 +480,7 @@ impl EventVec {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl<'a> IntoIterator for &'a EventVec {
     type IntoIter = Iter<'a>;
     type Item = Event;

src/backend/libc/event/mod.rs

@@ -5,5 +5,5 @@ pub(crate) mod types;
 #[cfg_attr(windows, path = "windows_syscalls.rs")]
 pub(crate) mod syscalls;
 
-#[cfg(all(feature = "alloc", linux_kernel))]
+#[cfg(linux_kernel)]
 pub mod epoll;

src/backend/linux_raw/conv.rs

@@ -581,7 +581,7 @@ impl<'a, Num: ArgNumber> From<crate::event::EventfdFlags> for ArgReg<'a, Num> {
     }
 }
 
-#[cfg(all(feature = "alloc", feature = "event"))]
+#[cfg(feature = "event")]
 impl<'a, Num: ArgNumber> From<crate::event::epoll::CreateFlags> for ArgReg<'a, Num> {
     #[inline]
     fn from(flags: crate::event::epoll::CreateFlags) -> Self {

src/backend/linux_raw/event/epoll.rs

@@ -79,6 +79,7 @@ use crate::backend::c;
 use crate::backend::event::syscalls;
 use crate::fd::{AsFd, AsRawFd, OwnedFd};
 use crate::io;
+#[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 use bitflags::bitflags;
 use core::ffi::c_void;
@@ -242,6 +243,8 @@ pub fn delete(epoll: impl AsFd, source: impl AsFd) -> io::Result<()> {
 ///
 /// For each event of interest, an element is written to `events`. On
 /// success, this returns the number of written elements.
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
 #[inline]
 pub fn wait(epoll: impl AsFd, event_list: &mut EventVec, timeout: c::c_int) -> io::Result<()> {
     // SAFETY: We're calling `epoll_wait` via FFI and we know how it
@@ -371,10 +374,12 @@ struct SixtyFourBitPointer {
 }
 
 /// A vector of `Event`s, plus context for interpreting them.
+#[cfg(feature = "alloc")]
 pub struct EventVec {
     events: Vec<Event>,
 }
 
+#[cfg(feature = "alloc")]
 impl EventVec {
     /// Constructs an `EventVec` from raw pointer, length, and capacity.
     ///
@@ -449,6 +454,7 @@ impl EventVec {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl<'a> IntoIterator for &'a EventVec {
     type IntoIter = Iter<'a>;
     type Item = Event;

src/backend/linux_raw/event/mod.rs

@@ -1,4 +1,3 @@
-#[cfg(feature = "alloc")]
 pub mod epoll;
 pub(crate) mod poll_fd;
 pub(crate) mod syscalls;

src/backend/linux_raw/event/syscalls.rs

@@ -6,17 +6,15 @@
 #![allow(unsafe_code, clippy::undocumented_unsafe_blocks)]
 
 use crate::backend::c;
-use crate::backend::conv::{c_int, c_uint, ret_owned_fd, ret_usize, slice_mut};
-use crate::event::{EventfdFlags, PollFd};
-use crate::fd::OwnedFd;
-use crate::io;
 #[cfg(feature = "alloc")]
-use {
-    crate::backend::conv::{by_ref, pass_usize, raw_fd, ret, zero},
-    crate::event::epoll,
-    crate::fd::BorrowedFd,
-    linux_raw_sys::general::{EPOLL_CTL_ADD, EPOLL_CTL_DEL, EPOLL_CTL_MOD},
+use crate::backend::conv::pass_usize;
+use crate::backend::conv::{
+    by_ref, c_int, c_uint, raw_fd, ret, ret_owned_fd, ret_usize, slice_mut, zero,
 };
+use crate::event::{epoll, EventfdFlags, PollFd};
+use crate::fd::{BorrowedFd, OwnedFd};
+use crate::io;
+use linux_raw_sys::general::{EPOLL_CTL_ADD, EPOLL_CTL_DEL, EPOLL_CTL_MOD};
 #[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
 use {
     crate::backend::conv::{opt_ref, size_of},
@@ -52,13 +50,11 @@ pub(crate) fn poll(fds: &mut [PollFd<'_>], timeout: c::c_int) -> io::Result<usiz
     }
 }
 
-#[cfg(feature = "alloc")]
 #[inline]
 pub(crate) fn epoll_create(flags: epoll::CreateFlags) -> io::Result<OwnedFd> {
     unsafe { ret_owned_fd(syscall_readonly!(__NR_epoll_create1, flags)) }
 }
 
-#[cfg(feature = "alloc")]
 #[inline]
 pub(crate) unsafe fn epoll_add(
     epfd: BorrowedFd<'_>,
@@ -74,7 +70,6 @@ pub(crate) unsafe fn epoll_add(
     ))
 }
 
-#[cfg(feature = "alloc")]
 #[inline]
 pub(crate) unsafe fn epoll_mod(
     epfd: BorrowedFd<'_>,
@@ -90,7 +85,6 @@ pub(crate) unsafe fn epoll_mod(
     ))
 }
 
-#[cfg(feature = "alloc")]
 #[inline]
 pub(crate) unsafe fn epoll_del(epfd: BorrowedFd<'_>, fd: c::c_int) -> io::Result<()> {
     ret(syscall_readonly!(

src/backend/linux_raw/fs/syscalls.rs

@@ -378,6 +378,7 @@ pub(crate) fn fadvise(fd: BorrowedFd<'_>, pos: u64, len: u64, advice: Advice) ->
             lo(len)
         ))
     }
+
     // On mips, the arguments are not reordered, and padding is inserted
     // instead to ensure alignment.
     #[cfg(any(target_arch = "mips", target_arch = "mips32r6"))]
@@ -393,6 +394,9 @@ pub(crate) fn fadvise(fd: BorrowedFd<'_>, pos: u64, len: u64, advice: Advice) ->
             advice
         ))
     }
+
+    // For all other 32-bit architectures, use `fadvise64_64` so that we get a
+    // 64-bit length.
     #[cfg(all(
         target_pointer_width = "32",
         not(any(
@@ -413,6 +417,8 @@ pub(crate) fn fadvise(fd: BorrowedFd<'_>, pos: u64, len: u64, advice: Advice) ->
             advice
         ))
     }
+
+    // On 64-bit architectures, use `fadvise64` which is sufficient.
     #[cfg(target_pointer_width = "64")]
     unsafe {
         ret(syscall_readonly!(

src/event/mod.rs

@@ -13,7 +13,7 @@ mod poll;
 #[cfg(solarish)]
 pub mod port;
 
-#[cfg(all(feature = "alloc", linux_kernel))]
+#[cfg(linux_kernel)]
 pub use crate::backend::event::epoll;
 #[cfg(any(
     linux_kernel,

src/io_uring.rs

@@ -32,9 +32,47 @@ use core::ptr::{null_mut, write_bytes};
 use linux_raw_sys::net;
 
 // Export types used in io_uring APIs.
-pub use crate::fs::{Advice, AtFlags, OFlags, RenameFlags, ResolveFlags, Statx};
+pub use crate::event::epoll::{
+    Event as EpollEvent, EventData as EpollEventData, EventFlags as EpollEventFlags,
+};
+pub use crate::fs::{Advice, AtFlags, Mode, OFlags, RenameFlags, ResolveFlags, Statx, StatxFlags};
+pub use crate::io::ReadWriteFlags;
 pub use crate::net::{RecvFlags, SendFlags, SocketFlags};
 pub use crate::timespec::Timespec;
+pub use linux_raw_sys::general::sigset_t;
+
+pub use net::{__kernel_sockaddr_storage as sockaddr_storage, msghdr, sockaddr, socklen_t};
+
+// Declare the `c_char` type for use with entries that take pointers
+// to C strings. Define it as unsigned or signed according to the platform
+// so that we match what Rust's `CStr` uses.
+//
+// When we can update to linux-raw-sys 0.5, we can remove this, as its
+// `c_char` type will declare this.
+/// The C `char` type.
+#[cfg(any(
+    target_arch = "aarch64",
+    target_arch = "arm",
+    target_arch = "msp430",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "riscv32",
+    target_arch = "riscv64",
+    target_arch = "s390x",
+))]
+#[allow(non_camel_case_types)]
+pub type c_char = u8;
+/// The C `char` type.
+#[cfg(any(
+    target_arch = "mips",
+    target_arch = "mips64",
+    target_arch = "sparc64",
+    target_arch = "x86",
+    target_arch = "x86_64",
+    target_arch = "xtensa",
+))]
+#[allow(non_camel_case_types)]
+pub type c_char = i8;
 
 mod sys {
     pub(super) use linux_raw_sys::io_uring::*;
@@ -1393,6 +1431,8 @@ impl Default for register_or_sqe_op_or_sqe_flags_union {
 fn io_uring_layouts() {
     use sys as c;
 
+    assert_eq_size!(io_uring_ptr, u64);
+
     check_renamed_type!(off_or_addr2_union, io_uring_sqe__bindgen_ty_1);
     check_renamed_type!(addr_or_splice_off_in_union, io_uring_sqe__bindgen_ty_2);
     check_renamed_type!(addr3_or_cmd_union, io_uring_sqe__bindgen_ty_6);

src/net/socket_addr_any.rs

@@ -11,7 +11,7 @@
 
 #[cfg(unix)]
 use crate::net::SocketAddrUnix;
-use crate::net::{AddressFamily, SocketAddrV4, SocketAddrV6};
+use crate::net::{AddressFamily, SocketAddr, SocketAddrV4, SocketAddrV6};
 use crate::{backend, io};
 #[cfg(feature = "std")]
 use core::fmt;
@@ -32,6 +32,16 @@ pub enum SocketAddrAny {
     Unix(SocketAddrUnix),
 }
 
+impl From<SocketAddr> for SocketAddrAny {
+    #[inline]
+    fn from(from: SocketAddr) -> Self {
+        match from {
+            SocketAddr::V4(v4) => Self::V4(v4),
+            SocketAddr::V6(v6) => Self::V6(v6),
+        }
+    }
+}
+
 impl From<SocketAddrV4> for SocketAddrAny {
     #[inline]
     fn from(from: SocketAddrV4) -> Self {