Add Motor OS std library port

Motor OS was added as a no-std Tier-3 target in
#146848
as x86_64-unknown-motor.

This patch/PR adds the std library for Motor OS.

While the patch may seem large, all it does is proxy
std pal calls to moto-rt. When there is some non-trivial
code (e.g. thread::spawn), it is quite similar, and often
identical, to what other platforms do.

Author: lasiotus

library/Cargo.lock

@@ -166,6 +166,16 @@ dependencies = [
  "rustc-std-workspace-core",
 ]
 
+[[package]]
+name = "moto-rt"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "058a2807a30527bee4c30df7ababe971cdde94372d4dbd1ff145bb403381436c"
+dependencies = [
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
 [[package]]
 name = "object"
 version = "0.37.3"
@@ -316,6 +326,7 @@ dependencies = [
  "hermit-abi",
  "libc",
  "miniz_oxide",
+ "moto-rt",
  "object",
  "panic_abort",
  "panic_unwind",

library/std/Cargo.toml

@@ -70,6 +70,9 @@ fortanix-sgx-abi = { version = "0.6.1", features = [
     'rustc-dep-of-std',
 ], public = true }
 
+[target.'cfg(target_os = "motor")'.dependencies]
+moto-rt = { version = "0.15", features = ['rustc-dep-of-std'], public = true }
+
 [target.'cfg(target_os = "hermit")'.dependencies]
 hermit-abi = { version = "0.5.0", features = [
     'rustc-dep-of-std',

library/std/build.rs

@@ -30,6 +30,7 @@ fn main() {
         || target_os == "windows"
         || target_os == "fuchsia"
         || (target_vendor == "fortanix" && target_env == "sgx")
+        || target_os == "motor"
         || target_os == "hermit"
         || target_os == "trusty"
         || target_os == "l4re"

library/std/src/os/fd/owned.rs

@@ -3,6 +3,9 @@
 #![stable(feature = "io_safety", since = "1.63.0")]
 #![deny(unsafe_op_in_unsafe_fn)]
 
+#[cfg(target_os = "motor")]
+use moto_rt::libc;
+
 use super::raw::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 #[cfg(not(target_os = "trusty"))]
 use crate::fs;
@@ -12,7 +15,8 @@ use crate::mem::ManuallyDrop;
     target_arch = "wasm32",
     target_env = "sgx",
     target_os = "hermit",
-    target_os = "trusty"
+    target_os = "trusty",
+    target_os = "motor"
 )))]
 use crate::sys::cvt;
 #[cfg(not(target_os = "trusty"))]
@@ -95,7 +99,12 @@ 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", target_os = "trusty")))]
+    #[cfg(not(any(
+        target_arch = "wasm32",
+        target_os = "hermit",
+        target_os = "trusty",
+        target_os = "motor"
+    )))]
     #[stable(feature = "io_safety", since = "1.63.0")]
     pub fn try_clone_to_owned(&self) -> crate::io::Result<OwnedFd> {
         // We want to atomically duplicate this file descriptor and set the
@@ -123,6 +132,15 @@ impl BorrowedFd<'_> {
     pub fn try_clone_to_owned(&self) -> crate::io::Result<OwnedFd> {
         Err(crate::io::Error::UNSUPPORTED_PLATFORM)
     }
+
+    /// Creates a new `OwnedFd` instance that shares the same underlying file
+    /// description as the existing `BorrowedFd` instance.
+    #[cfg(target_os = "motor")]
+    #[stable(feature = "io_safety", since = "1.63.0")]
+    pub fn try_clone_to_owned(&self) -> crate::io::Result<OwnedFd> {
+        let fd = moto_rt::fs::duplicate(self.as_raw_fd()).map_err(crate::sys::map_motor_error)?;
+        Ok(unsafe { OwnedFd::from_raw_fd(fd) })
+    }
 }
 
 #[stable(feature = "io_safety", since = "1.63.0")]

library/std/src/os/fd/raw.rs

@@ -4,13 +4,17 @@
 
 #[cfg(target_os = "hermit")]
 use hermit_abi as libc;
+#[cfg(target_os = "motor")]
+use moto_rt::libc;
 
+#[cfg(target_os = "motor")]
+use super::owned::OwnedFd;
 #[cfg(not(target_os = "trusty"))]
 use crate::fs;
 use crate::io;
 #[cfg(target_os = "hermit")]
 use crate::os::hermit::io::OwnedFd;
-#[cfg(not(target_os = "hermit"))]
+#[cfg(all(not(target_os = "hermit"), not(target_os = "motor")))]
 use crate::os::raw;
 #[cfg(all(doc, not(target_arch = "wasm32")))]
 use crate::os::unix::io::AsFd;
@@ -23,10 +27,10 @@ use crate::sys_common::{AsInner, FromInner, IntoInner};
 
 /// Raw file descriptors.
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg(not(target_os = "hermit"))]
+#[cfg(all(not(target_os = "hermit"), not(target_os = "motor")))]
 pub type RawFd = raw::c_int;
 #[stable(feature = "rust1", since = "1.0.0")]
-#[cfg(target_os = "hermit")]
+#[cfg(any(target_os = "hermit", target_os = "motor"))]
 pub type RawFd = i32;
 
 /// A trait to extract the raw file descriptor from an underlying object.

library/std/src/os/mod.rs

@@ -155,6 +155,8 @@ pub mod ios;
 pub mod l4re;
 #[cfg(target_os = "macos")]
 pub mod macos;
+#[cfg(target_os = "motor")]
+pub mod motor;
 #[cfg(target_os = "netbsd")]
 pub mod netbsd;
 #[cfg(target_os = "nto")]
@@ -182,7 +184,14 @@ pub mod vxworks;
 #[cfg(target_os = "xous")]
 pub mod xous;
 
-#[cfg(any(unix, target_os = "hermit", target_os = "trusty", target_os = "wasi", doc))]
+#[cfg(any(
+    unix,
+    target_os = "hermit",
+    target_os = "trusty",
+    target_os = "wasi",
+    target_os = "motor",
+    doc
+))]
 pub mod fd;
 
 #[cfg(any(target_os = "linux", target_os = "android", target_os = "cygwin", doc))]

library/std/src/os/motor/ffi.rs

@@ -0,0 +1,37 @@
+//! Motor OS-specific extensions to primitives in the [`std::ffi`] module.
+#![unstable(feature = "motor_ext", issue = "147456")]
+
+use crate::ffi::{OsStr, OsString};
+use crate::sealed::Sealed;
+
+/// Motor OS-specific extensions to [`OsString`].
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
+pub trait OsStringExt: Sealed {
+    /// Motor OS strings are utf-8, and thus just strings.
+    fn as_str(&self) -> &str;
+}
+
+impl OsStringExt for OsString {
+    #[inline]
+    fn as_str(&self) -> &str {
+        self.to_str().unwrap()
+    }
+}
+
+/// Motor OS-specific extensions to [`OsString`].
+///
+/// This trait is sealed: it cannot be implemented outside the standard library.
+/// This is so that future additional methods are not breaking changes.
+pub trait OsStrExt: Sealed {
+    /// Motor OS strings are utf-8, and thus just strings.
+    fn as_str(&self) -> &str;
+}
+
+impl OsStrExt for OsStr {
+    #[inline]
+    fn as_str(&self) -> &str {
+        self.to_str().unwrap()
+    }
+}

library/std/src/os/motor/mod.rs

@@ -0,0 +1,4 @@
+#![unstable(feature = "motor_ext", issue = "147456")]
+
+pub mod ffi;
+pub mod process;

library/std/src/os/motor/process.rs

@@ -0,0 +1,15 @@
+#![unstable(feature = "motor_ext", issue = "147456")]
+
+use crate::sealed::Sealed;
+use crate::sys_common::AsInner;
+
+pub trait ChildExt: Sealed {
+    /// Extracts the main thread raw handle, without taking ownership
+    fn sys_handle(&self) -> u64;
+}
+
+impl ChildExt for crate::process::Child {
+    fn sys_handle(&self) -> u64 {
+        self.as_inner().handle()
+    }
+}

library/std/src/sys/alloc/mod.rs

@@ -83,6 +83,9 @@ cfg_select! {
     target_os = "hermit" => {
         mod hermit;
     }
+    target_os = "motor" => {
+        mod motor;
+    }
     all(target_vendor = "fortanix", target_env = "sgx") => {
         mod sgx;
     }