Add minimal support for Hermit OS

src/backend/libc/io/errno.rs

@@ -791,7 +791,7 @@ impl Errno {
     #[cfg(not(target_os = "l4re"))]
     pub const NOTSOCK: Self = Self(c::ENOTSOCK);
     /// `ENOTSUP`
-    #[cfg(not(any(windows, target_os = "redox")))]
+    #[cfg(not(any(windows, target_os = "hermit", target_os = "redox")))]
     pub const NOTSUP: Self = Self(c::ENOTSUP);
     /// `ENOTTY`
     #[cfg(not(windows))]

src/backend/libc/io/syscalls.rs

@@ -43,6 +43,7 @@ pub(crate) fn write(fd: BorrowedFd<'_>, buf: &[u8]) -> io::Result<usize> {
     }
 }
 
+#[cfg(not(target_os = "hermit"))]
 pub(crate) unsafe fn pread(
     fd: BorrowedFd<'_>,
     buf: (*mut u8, usize),
@@ -59,6 +60,7 @@ pub(crate) unsafe fn pread(
     ret_usize(c::pread(borrowed_fd(fd), buf.0.cast(), len, offset))
 }
 
+#[cfg(not(target_os = "hermit"))]
 pub(crate) fn pwrite(fd: BorrowedFd<'_>, buf: &[u8], offset: u64) -> io::Result<usize> {
     let len = min(buf.len(), READ_LIMIT);
 
@@ -76,8 +78,8 @@ pub(crate) fn readv(fd: BorrowedFd<'_>, bufs: &mut [IoSliceMut<'_>]) -> io::Resu
     unsafe {
         ret_usize(c::readv(
             borrowed_fd(fd),
-            bufs.as_ptr().cast::<c::iovec>(),
-            min(bufs.len(), MAX_IOV) as c::c_int,
+            bufs.as_ptr().cast(),
+            min(bufs.len(), MAX_IOV) as _,
         ))
     }
 }
@@ -87,8 +89,8 @@ pub(crate) fn writev(fd: BorrowedFd<'_>, bufs: &[IoSlice<'_>]) -> io::Result<usi
     unsafe {
         ret_usize(c::writev(
             borrowed_fd(fd),
-            bufs.as_ptr().cast::<c::iovec>(),
-            min(bufs.len(), MAX_IOV) as c::c_int,
+            bufs.as_ptr().cast(),
+            min(bufs.len(), MAX_IOV) as _,
         ))
     }
 }
@@ -97,6 +99,7 @@ pub(crate) fn writev(fd: BorrowedFd<'_>, bufs: &[IoSlice<'_>]) -> io::Result<usi
     target_os = "cygwin",
     target_os = "espidf",
     target_os = "haiku",
+    target_os = "hermit",
     target_os = "horizon",
     target_os = "nto",
     target_os = "redox",
@@ -128,6 +131,7 @@ pub(crate) fn preadv(
     target_os = "cygwin",
     target_os = "espidf",
     target_os = "haiku",
+    target_os = "hermit",
     target_os = "nto",
     target_os = "horizon",
     target_os = "redox",
@@ -234,16 +238,18 @@ pub(crate) unsafe fn ioctl_readonly(
     ioctl(fd, request, arg)
 }
 
+#[cfg(not(target_os = "hermit"))]
 pub(crate) fn fcntl_getfd(fd: BorrowedFd<'_>) -> io::Result<FdFlags> {
     let flags = unsafe { ret_c_int(c::fcntl(borrowed_fd(fd), c::F_GETFD))? };
     Ok(FdFlags::from_bits_retain(bitcast!(flags)))
 }
 
+#[cfg(not(target_os = "hermit"))]
 pub(crate) fn fcntl_setfd(fd: BorrowedFd<'_>, flags: FdFlags) -> io::Result<()> {
     unsafe { ret(c::fcntl(borrowed_fd(fd), c::F_SETFD, flags.bits())) }
 }
 
-#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
+#[cfg(not(any(target_os = "espidf", target_os = "hermit", target_os = "wasi")))]
 pub(crate) fn fcntl_dupfd_cloexec(fd: BorrowedFd<'_>, min: RawFd) -> io::Result<OwnedFd> {
     unsafe { ret_owned_fd(c::fcntl(borrowed_fd(fd), c::F_DUPFD_CLOEXEC, min)) }
 }
@@ -259,7 +265,7 @@ pub(crate) fn dup(fd: BorrowedFd<'_>) -> io::Result<OwnedFd> {
 }
 
 #[allow(clippy::needless_pass_by_ref_mut)]
-#[cfg(not(target_os = "wasi"))]
+#[cfg(not(any(target_os = "hermit", target_os = "wasi")))]
 pub(crate) fn dup2(fd: BorrowedFd<'_>, new: &mut OwnedFd) -> io::Result<()> {
     unsafe { ret_discarded_fd(c::dup2(borrowed_fd(fd), borrowed_fd(new.as_fd()))) }
 }
@@ -272,6 +278,7 @@ pub(crate) fn dup2(fd: BorrowedFd<'_>, new: &mut OwnedFd) -> io::Result<()> {
     target_os = "dragonfly",
     target_os = "espidf",
     target_os = "haiku",
+    target_os = "hermit",
     target_os = "horizon",
     target_os = "nto",
     target_os = "redox",

src/backend/libc/io/types.rs

@@ -55,6 +55,7 @@ bitflags! {
             apple,
             target_os = "aix",
             target_os = "android",
+            target_os = "hermit",
             target_os = "redox",
         )))] // Android 5.0 has dup3, but libc doesn't have bindings
         const CLOEXEC = bitcast!(c::O_CLOEXEC);

src/io/dup.rs

@@ -84,7 +84,7 @@ pub fn dup<Fd: AsFd>(fd: Fd) -> io::Result<OwnedFd> {
 /// [`stdio::dup2_stdin`]: crate::stdio::dup2_stdin
 /// [`stdio::dup2_stdout`]: crate::stdio::dup2_stdout
 /// [`stdio::dup2_stderr`]: crate::stdio::dup2_stderr
-#[cfg(not(target_os = "wasi"))]
+#[cfg(not(any(target_os = "hermit", target_os = "wasi")))]
 #[inline]
 pub fn dup2<Fd: AsFd>(fd: Fd, new: &mut OwnedFd) -> io::Result<()> {
     backend::io::syscalls::dup2(fd.as_fd(), new)
@@ -114,6 +114,7 @@ pub fn dup2<Fd: AsFd>(fd: Fd, new: &mut OwnedFd) -> io::Result<()> {
 #[cfg(not(any(
     target_os = "aix",
     target_os = "espidf",
+    target_os = "hermit",
     target_os = "horizon",
     target_os = "nto",
     target_os = "vita",

src/io/fcntl.rs

@@ -35,6 +35,7 @@ pub use backend::io::types::FdFlags;
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=fcntl&section=2
 /// [illumos]: https://illumos.org/man/2/fcntl
 /// [glibc]: https://sourceware.org/glibc/manual/latest/html_node/Control-Operations.html#index-fcntl-function
+#[cfg(not(target_os = "hermit"))]
 #[inline]
 #[doc(alias = "F_GETFD")]
 pub fn fcntl_getfd<Fd: AsFd>(fd: Fd) -> io::Result<FdFlags> {
@@ -63,6 +64,7 @@ pub fn fcntl_getfd<Fd: AsFd>(fd: Fd) -> io::Result<FdFlags> {
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=fcntl&section=2
 /// [illumos]: https://illumos.org/man/2/fcntl
 /// [glibc]: https://sourceware.org/glibc/manual/latest/html_node/Control-Operations.html#index-fcntl-function
+#[cfg(not(target_os = "hermit"))]
 #[inline]
 #[doc(alias = "F_SETFD")]
 pub fn fcntl_setfd<Fd: AsFd>(fd: Fd, flags: FdFlags) -> io::Result<()> {
@@ -99,7 +101,7 @@ pub fn fcntl_setfd<Fd: AsFd>(fd: Fd, flags: FdFlags) -> io::Result<()> {
 /// [illumos]: https://illumos.org/man/2/fcntl
 /// [glibc]: https://sourceware.org/glibc/manual/latest/html_node/Control-Operations.html#index-fcntl-function
 /// [file description]: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap03.html#tag_03_258
-#[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
+#[cfg(not(any(target_os = "espidf", target_os = "hermit", target_os = "wasi")))]
 #[inline]
 #[doc(alias = "F_DUPFD_CLOEXEC")]
 pub fn fcntl_dupfd_cloexec<Fd: AsFd>(fd: Fd, min: RawFd) -> io::Result<OwnedFd> {

src/io/ioctl.rs

@@ -86,7 +86,12 @@ pub fn ioctl_fionbio<Fd: AsFd>(fd: Fd, value: bool) -> io::Result<()> {
 /// [FreeBSD]: https://man.freebsd.org/cgi/man.cgi?query=ioctl&sektion=2#GENERIC%09IOCTLS
 /// [NetBSD]: https://man.netbsd.org/ioctl.2#GENERIC%20IOCTLS
 /// [OpenBSD]: https://man.openbsd.org/ioctl.2#GENERIC_IOCTLS
-#[cfg(not(any(target_os = "espidf", target_os = "horizon", target_os = "vita")))]
+#[cfg(not(any(
+    target_os = "espidf",
+    target_os = "hermit",
+    target_os = "horizon",
+    target_os = "vita"
+)))]
 #[inline]
 #[doc(alias = "FIONREAD")]
 pub fn ioctl_fionread<Fd: AsFd>(fd: Fd) -> io::Result<u64> {

src/io/read_write.rs

@@ -92,7 +92,7 @@ pub fn write<Fd: AsFd>(fd: Fd, buf: &[u8]) -> io::Result<usize> {
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=pread&section=2
 /// [illumos]: https://illumos.org/man/2/pread
 /// [glibc]: https://sourceware.org/glibc/manual/latest/html_node/I_002fO-Primitives.html#index-pread64
-#[cfg(not(windows))]
+#[cfg(not(any(windows, target_os = "hermit")))]
 #[inline]
 pub fn pread<Fd: AsFd, Buf: Buffer<u8>>(
     fd: Fd,
@@ -131,7 +131,7 @@ pub fn pread<Fd: AsFd, Buf: Buffer<u8>>(
 /// [DragonFly BSD]: https://man.dragonflybsd.org/?command=pwrite&section=2
 /// [illumos]: https://illumos.org/man/2/pwrite
 /// [glibc]: https://sourceware.org/glibc/manual/latest/html_node/I_002fO-Primitives.html#index-pwrite64
-#[cfg(not(windows))]
+#[cfg(not(any(windows, target_os = "hermit")))]
 #[inline]
 pub fn pwrite<Fd: AsFd>(fd: Fd, buf: &[u8], offset: u64) -> io::Result<usize> {
     backend::io::syscalls::pwrite(fd.as_fd(), buf, offset)
@@ -217,6 +217,7 @@ pub fn writev<Fd: AsFd>(fd: Fd, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
     target_os = "cygwin",
     target_os = "espidf",
     target_os = "haiku",
+    target_os = "hermit",
     target_os = "horizon",
     target_os = "nto",
     target_os = "redox",
@@ -256,6 +257,7 @@ pub fn preadv<Fd: AsFd>(fd: Fd, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io:
     target_os = "cygwin",
     target_os = "espidf",
     target_os = "haiku",
+    target_os = "hermit",
     target_os = "horizon",
     target_os = "nto",
     target_os = "redox",

src/ioctl/mod.rs

@@ -330,6 +330,7 @@ type _Opcode = c::c_ulong;
     target_os = "aix",
     target_os = "cygwin",
     target_os = "fuchsia",
+    target_os = "hermit",
     target_os = "emscripten",
     target_os = "nto",
     target_os = "wasi",

src/lib.rs

@@ -185,7 +185,15 @@ pub(crate) mod msan;
 // versions of libc and not others.
 #[cfg(any(
     all(linux_raw, feature = "use-libc-auxv"),
-    all(libc, not(any(windows, target_os = "espidf", target_os = "wasi")))
+    all(
+        libc,
+        not(any(
+            windows,
+            target_os = "espidf",
+            target_os = "hermit",
+            target_os = "wasi"
+        ))
+    )
 ))]
 #[macro_use]
 mod weak;

src/maybe_polyfill/no_std/os/fd/owned.rs

@@ -101,7 +101,12 @@ impl BorrowedFd<'_> {
 impl OwnedFd {
     /// Creates a new `OwnedFd` instance that shares the same underlying file handle
     /// as the existing `OwnedFd` instance.
-    #[cfg(not(target_arch = "wasm32"))]
+    #[cfg(not(any(
+        target_os = "hermit",
+        target_os = "motor",
+        target_os = "trusty",
+        target_os = "wasi"
+    )))]
     pub fn try_clone(&self) -> crate::io::Result<Self> {
         // We want to atomically duplicate this file descriptor and set the
         // CLOEXEC flag, and currently that's done via F_DUPFD_CLOEXEC. This
@@ -121,7 +126,12 @@ impl OwnedFd {
 
     /// Creates a new `OwnedFd` instance that shares the same underlying file handle
     /// as the existing `OwnedFd` instance.
-    #[cfg(target_arch = "wasm32")]
+    #[cfg(any(
+        target_os = "hermit",
+        target_os = "motor",
+        target_os = "trusty",
+        target_os = "wasi"
+    ))]
     pub fn try_clone(&self) -> crate::io::Result<Self> {
         Err(crate::io::Errno::NOSYS)
     }
@@ -130,7 +140,12 @@ impl OwnedFd {
 impl BorrowedFd<'_> {
     /// Creates a new `OwnedFd` instance that shares the same underlying file
     /// description as the existing `BorrowedFd` instance.
-    #[cfg(not(any(target_arch = "wasm32", target_os = "hermit")))]
+    #[cfg(not(any(
+        target_os = "hermit",
+        target_os = "motor",
+        target_os = "trusty",
+        target_os = "wasi"
+    )))]
     #[cfg_attr(staged_api, stable(feature = "io_safety", since = "1.63.0"))]
     pub fn try_clone_to_owned(&self) -> crate::io::Result<OwnedFd> {
         // Avoid using file descriptors below 3 as they are used for stdio
@@ -153,7 +168,12 @@ impl BorrowedFd<'_> {
 
     /// Creates a new `OwnedFd` instance that shares the same underlying file
     /// description as the existing `BorrowedFd` instance.
-    #[cfg(any(target_arch = "wasm32", target_os = "hermit"))]
+    #[cfg(any(
+        target_os = "hermit",
+        target_os = "motor",
+        target_os = "trusty",
+        target_os = "wasi"
+    ))]
     #[cfg_attr(staged_api, stable(feature = "io_safety", since = "1.63.0"))]
     pub fn try_clone_to_owned(&self) -> crate::io::Result<OwnedFd> {
         Err(crate::io::Errno::NOSYS)

src/maybe_polyfill/no_std/os/mod.rs

@@ -1,4 +1,4 @@
-#[cfg(any(unix, target_os = "wasi"))]
+#[cfg(any(unix, target_os = "hermit", target_os = "wasi"))]
 pub mod fd;
 #[cfg(windows)]
 pub mod windows;

src/maybe_polyfill/std/mod.rs

@@ -21,7 +21,12 @@ pub mod os {
     pub mod fd {
         // Change to use `std::os::fd` when MSRV becomes Rust 1.66 or higher.
 
-        #[cfg(target_os = "wasi")]
+        #[cfg(any(
+            target_os = "hermit",
+            target_os = "motor",
+            target_os = "trusty",
+            target_os = "wasi"
+        ))]
         pub use std::os::fd::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
         #[cfg(unix)]
         pub use std::os::unix::io::{

tests/backends.rs

@@ -82,7 +82,7 @@ fn test_backends() {
 
     #[cfg(windows)]
     let libc_dep = "windows-sys";
-    #[cfg(any(unix, target_os = "wasi"))]
+    #[cfg(not(windows))]
     let libc_dep = "libc";
 
     // Test the use-libc crate, which enables the "use-libc" cargo feature.

tests/io/ioctl.rs

@@ -1,5 +1,10 @@
 // `ioctl_fionread` on Windows doesn't work on files.
-#[cfg(not(any(windows, target_os = "cygwin", target_os = "haiku")))]
+#[cfg(not(any(
+    windows,
+    target_os = "cygwin",
+    target_os = "hermit",
+    target_os = "haiku"
+)))]
 #[test]
 fn test_ioctls() {
     let file = std::fs::File::open("Cargo.toml").unwrap();