Rollup merge of #153623 - joboet:move_pal_os, r=Mark-Simulacrum

std: move `sys::pal::os` to `sys::paths`

Part of rust-lang/rust#117276.

After rust-lang/rust#150723, rust-lang/rust#153130, rust-lang/rust#153341 and rust-lang/rust#153413, `sys::pal::os` only contains default-path related functions (like `getcwd` and the `PATH`-splitting logic). In line with rust-lang/rust#117276, this PR thus moves all these implementations into a new module in `sys`: `sys::paths`.

~There is one functional change here: The `chdir` implementation on SGX used to use `sgx_ineffective` which silently fails, but now returns an error unconditionally – I think that's much more reasonable given that SGX doesn't support filesystem stuff at all.~

I've corrected the misleading panic messages in `temp_dir` for UEFI and WASI, aside from that, this PR only consists of code moves.

CC @jethrogb @raoulstrackx @aditijannu for the SGX change (resolved)

library/std/src/env.rs

@@ -15,7 +15,7 @@
 use crate::num::NonZero;
 use crate::ops::Try;
 use crate::path::{Path, PathBuf};
-use crate::sys::{env as env_imp, os as os_imp};
+use crate::sys::{env as env_imp, paths as paths_imp};
 use crate::{array, fmt, io, sys};
 
 /// Returns the current working directory as a [`PathBuf`].
@@ -51,7 +51,7 @@
 #[doc(alias = "GetCurrentDirectory")]
 #[stable(feature = "env", since = "1.0.0")]
 pub fn current_dir() -> io::Result<PathBuf> {
-    os_imp::getcwd()
+    paths_imp::getcwd()
 }
 
 /// Changes the current working directory to the specified path.
@@ -78,7 +78,7 @@ pub fn current_dir() -> io::Result<PathBuf> {
 #[doc(alias = "chdir", alias = "SetCurrentDirectory", alias = "SetCurrentDirectoryW")]
 #[stable(feature = "env", since = "1.0.0")]
 pub fn set_current_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
-    os_imp::chdir(path.as_ref())
+    paths_imp::chdir(path.as_ref())
 }
 
 /// An iterator over a snapshot of the environment variables of this process.
@@ -444,7 +444,7 @@ pub unsafe fn remove_var<K: AsRef<OsStr>>(key: K) {
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "env", since = "1.0.0")]
 pub struct SplitPaths<'a> {
-    inner: os_imp::SplitPaths<'a>,
+    inner: paths_imp::SplitPaths<'a>,
 }
 
 /// Parses input according to platform conventions for the `PATH`
@@ -480,7 +480,7 @@ pub struct SplitPaths<'a> {
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn split_paths<T: AsRef<OsStr> + ?Sized>(unparsed: &T) -> SplitPaths<'_> {
-    SplitPaths { inner: os_imp::split_paths(unparsed.as_ref()) }
+    SplitPaths { inner: paths_imp::split_paths(unparsed.as_ref()) }
 }
 
 #[stable(feature = "env", since = "1.0.0")]
@@ -508,7 +508,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 #[derive(Debug)]
 #[stable(feature = "env", since = "1.0.0")]
 pub struct JoinPathsError {
-    inner: os_imp::JoinPathsError,
+    inner: paths_imp::JoinPathsError,
 }
 
 /// Joins a collection of [`Path`]s appropriately for the `PATH`
@@ -579,7 +579,7 @@ pub fn join_paths<I, T>(paths: I) -> Result<OsString, JoinPathsError>
     I: IntoIterator<Item = T>,
     T: AsRef<OsStr>,
 {
-    os_imp::join_paths(paths.into_iter()).map_err(|e| JoinPathsError { inner: e })
+    paths_imp::join_paths(paths.into_iter()).map_err(|e| JoinPathsError { inner: e })
 }
 
 #[stable(feature = "env", since = "1.0.0")]
@@ -641,7 +641,7 @@ fn description(&self) -> &str {
 #[must_use]
 #[stable(feature = "env", since = "1.0.0")]
 pub fn home_dir() -> Option<PathBuf> {
-    os_imp::home_dir()
+    paths_imp::home_dir()
 }
 
 /// Returns the path of a temporary directory.
@@ -701,7 +701,7 @@ pub fn home_dir() -> Option<PathBuf> {
 #[doc(alias = "GetTempPath", alias = "GetTempPath2")]
 #[stable(feature = "env", since = "1.0.0")]
 pub fn temp_dir() -> PathBuf {
-    os_imp::temp_dir()
+    paths_imp::temp_dir()
 }
 
 /// Returns the full filesystem path of the current running executable.
@@ -752,7 +752,7 @@ pub fn temp_dir() -> PathBuf {
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn current_exe() -> io::Result<PathBuf> {
-    os_imp::current_exe()
+    paths_imp::current_exe()
 }
 
 /// An iterator over the arguments of a process, yielding a [`String`] value for

library/std/src/sys/args/windows.rs

@@ -12,9 +12,9 @@
 use crate::os::windows::prelude::*;
 use crate::path::{Path, PathBuf};
 use crate::sys::helpers::WStrUnits;
-use crate::sys::pal::os::current_exe;
 use crate::sys::pal::{ensure_no_nuls, fill_utf16_buf};
 use crate::sys::path::get_long_path;
+use crate::sys::paths::current_exe;
 use crate::sys::{AsInner, c, to_u16s};
 use crate::{io, iter, ptr};
 

library/std/src/sys/io/error/windows.rs

@@ -1,6 +1,9 @@
 use crate::sys::pal::{api, c};
 use crate::{io, ptr};
 
+#[cfg(test)]
+mod tests;
+
 pub fn errno() -> i32 {
     api::get_last_error().code as i32
 }

library/std/src/sys/io/error/windows/tests.rs

@@ -1,5 +1,5 @@
 use crate::io::Error;
-use crate::sys::c;
+use crate::sys::pal::c;
 
 // tests `error_string` above
 #[test]

library/std/src/sys/mod.rs

@@ -18,6 +18,7 @@
 pub mod net;
 pub mod os_str;
 pub mod path;
+pub mod paths;
 pub mod pipe;
 pub mod platform_version;
 pub mod process;

library/std/src/sys/pal/hermit/mod.rs

@@ -22,7 +22,6 @@
 use crate::sys::env;
 
 pub mod futex;
-pub mod os;
 pub mod time;
 
 pub fn unsupported<T>() -> io::Result<T> {

library/std/src/sys/pal/hermit/os.rs

@@ -1,57 +0,0 @@
-use crate::ffi::{OsStr, OsString};
-use crate::marker::PhantomData;
-use crate::path::{self, PathBuf};
-use crate::sys::unsupported;
-use crate::{fmt, io};
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    Ok(PathBuf::from("/"))
-}
-
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    unsupported()
-}
-
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on hermit yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn temp_dir() -> PathBuf {
-    PathBuf::from("/tmp")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/motor/mod.rs

@@ -1,7 +1,5 @@
 #![allow(unsafe_op_in_unsafe_fn)]
 
-pub mod os;
-
 pub use moto_rt::futex;
 
 use crate::io;

library/std/src/sys/pal/motor/os.rs

@@ -1,64 +0,0 @@
-use super::map_motor_error;
-use crate::error::Error as StdError;
-use crate::ffi::{OsStr, OsString};
-use crate::marker::PhantomData;
-use crate::os::motor::ffi::OsStrExt;
-use crate::path::{self, PathBuf};
-use crate::{fmt, io};
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    moto_rt::fs::getcwd().map(PathBuf::from).map_err(map_motor_error)
-}
-
-pub fn chdir(path: &path::Path) -> io::Result<()> {
-    moto_rt::fs::chdir(path.as_os_str().as_str()).map_err(map_motor_error)
-}
-
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on this platform yet".fmt(f)
-    }
-}
-
-impl StdError for JoinPathsError {
-    #[allow(deprecated)]
-    fn description(&self) -> &str {
-        "not supported on this platform yet"
-    }
-}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    moto_rt::process::current_exe().map(PathBuf::from).map_err(map_motor_error)
-}
-
-pub fn temp_dir() -> PathBuf {
-    PathBuf::from(moto_rt::fs::TEMP_DIR)
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/sgx/mod.rs

@@ -10,7 +10,6 @@
 
 pub mod abi;
 mod libunwind_integration;
-pub mod os;
 pub mod thread_parking;
 pub mod waitqueue;
 

library/std/src/sys/pal/sgx/os.rs

@@ -1,57 +0,0 @@
-use crate::ffi::{OsStr, OsString};
-use crate::marker::PhantomData;
-use crate::path::{self, PathBuf};
-use crate::sys::{sgx_ineffective, unsupported};
-use crate::{fmt, io};
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    sgx_ineffective(())
-}
-
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported in SGX yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn temp_dir() -> PathBuf {
-    panic!("no filesystem in SGX")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/solid/mod.rs

@@ -19,7 +19,6 @@ pub mod itron {
 // `error` is `pub(crate)` so that it can be accessed by `itron/error.rs` as
 // `crate::sys::error`
 pub(crate) mod error;
-pub mod os;
 pub use self::itron::thread_parking;
 
 // SAFETY: must be called only once during runtime initialization.

library/std/src/sys/pal/solid/os.rs

@@ -1,56 +0,0 @@
-use super::unsupported;
-use crate::ffi::{OsStr, OsString};
-use crate::path::{self, PathBuf};
-use crate::{fmt, io};
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    unsupported()
-}
-
-pub struct SplitPaths<'a>(&'a !);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        *self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on this platform yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn temp_dir() -> PathBuf {
-    panic!("no standard temporary directory on this platform")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/teeos/mod.rs

@@ -7,7 +7,6 @@
 #![allow(dead_code)]
 
 pub mod conf;
-pub mod os;
 #[path = "../unix/time.rs"]
 pub mod time;
 

library/std/src/sys/pal/teeos/os.rs

@@ -1,62 +0,0 @@
-//! Implementation of `std::os` functionality for teeos
-
-use core::marker::PhantomData;
-
-use super::unsupported;
-use crate::ffi::{OsStr, OsString};
-use crate::path::PathBuf;
-use crate::{fmt, io, path};
-
-// Everything below are stubs and copied from unsupported.rs
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    unsupported()
-}
-
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on this platform yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn temp_dir() -> PathBuf {
-    panic!("no filesystem on this platform")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/trusty/mod.rs

@@ -3,7 +3,5 @@
 #[path = "../unsupported/common.rs"]
 #[deny(unsafe_op_in_unsafe_fn)]
 mod common;
-#[path = "../unsupported/os.rs"]
-pub mod os;
 
 pub use common::*;

library/std/src/sys/pal/uefi/mod.rs

@@ -14,7 +14,6 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod helpers;
-pub mod os;
 pub mod system_time;
 
 #[cfg(test)]

library/std/src/sys/pal/unix/mod.rs

@@ -8,7 +8,6 @@
 pub mod futex;
 #[cfg(target_os = "linux")]
 pub mod linux;
-pub mod os;
 pub mod stack_overflow;
 pub mod sync;
 pub mod thread_parking;

library/std/src/sys/pal/unsupported/mod.rs

@@ -1,6 +1,4 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
-pub mod os;
-
 mod common;
 pub use common::*;

library/std/src/sys/pal/unsupported/os.rs

@@ -1,57 +0,0 @@
-use super::unsupported;
-use crate::ffi::{OsStr, OsString};
-use crate::marker::PhantomData;
-use crate::path::{self, PathBuf};
-use crate::{fmt, io};
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    unsupported()
-}
-
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on this platform yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn temp_dir() -> PathBuf {
-    panic!("no filesystem on this platform")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/vexos/mod.rs

@@ -1,6 +1,3 @@
-#[path = "../unsupported/os.rs"]
-pub mod os;
-
 #[expect(dead_code)]
 #[path = "../unsupported/common.rs"]
 mod unsupported_common;

library/std/src/sys/pal/wasi/mod.rs

@@ -10,7 +10,6 @@
 #[allow(unused)]
 #[path = "../wasm/atomics/futex.rs"]
 pub mod futex;
-pub mod os;
 pub mod stack_overflow;
 #[path = "../unix/time.rs"]
 pub mod time;

library/std/src/sys/pal/wasm/mod.rs

@@ -16,9 +16,6 @@
 
 #![deny(unsafe_op_in_unsafe_fn)]
 
-#[path = "../unsupported/os.rs"]
-pub mod os;
-
 #[cfg(target_feature = "atomics")]
 #[path = "atomics/futex.rs"]
 pub mod futex;

library/std/src/sys/pal/windows/mod.rs

@@ -18,7 +18,6 @@
 #[cfg(not(target_vendor = "win7"))]
 pub mod futex;
 pub mod handle;
-pub mod os;
 pub mod time;
 cfg_select! {
     // We don't care about printing nice error messages for panic=immediate-abort

library/std/src/sys/pal/xous/mod.rs

@@ -1,6 +1,5 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-pub mod os;
 pub mod params;
 
 #[path = "../unsupported/common.rs"]

library/std/src/sys/pal/xous/os.rs

@@ -1,57 +0,0 @@
-use super::unsupported;
-use crate::ffi::{OsStr, OsString};
-use crate::marker::PhantomData;
-use crate::path::{self, PathBuf};
-use crate::{fmt, io};
-
-pub fn getcwd() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn chdir(_: &path::Path) -> io::Result<()> {
-    unsupported()
-}
-
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on this platform yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
-pub fn temp_dir() -> PathBuf {
-    panic!("no filesystem on this platform")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
-}

library/std/src/sys/pal/zkvm/mod.rs

@@ -11,7 +11,6 @@
 pub const WORD_SIZE: usize = size_of::<u32>();
 
 pub mod abi;
-pub mod os;
 
 use crate::io as std_io;
 

library/std/src/sys/paths/hermit.rs

@@ -0,0 +1,10 @@
+use crate::io;
+use crate::path::PathBuf;
+
+pub fn getcwd() -> io::Result<PathBuf> {
+    Ok(PathBuf::from("/"))
+}
+
+pub fn temp_dir() -> PathBuf {
+    PathBuf::from("/tmp")
+}

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

@@ -0,0 +1,59 @@
+cfg_select! {
+    target_os = "hermit" => {
+        mod hermit;
+        #[expect(dead_code)]
+        mod unsupported;
+        mod imp {
+            pub use super::hermit::{getcwd, temp_dir};
+            pub use super::unsupported::{chdir, SplitPaths, split_paths, JoinPathsError, join_paths, current_exe, home_dir};
+        }
+    }
+    target_os = "motor" => {
+        mod motor;
+        #[expect(dead_code)]
+        mod unsupported;
+        mod imp {
+            pub use super::motor::{getcwd, chdir, current_exe, temp_dir};
+            pub use super::unsupported::{SplitPaths, split_paths, JoinPathsError, join_paths, home_dir};
+        }
+    }
+    all(target_vendor = "fortanix", target_env = "sgx") => {
+        mod sgx;
+        #[expect(dead_code)]
+        mod unsupported;
+        mod imp {
+            pub use super::sgx::chdir;
+            pub use super::unsupported::{getcwd, SplitPaths, split_paths, JoinPathsError, join_paths, current_exe, temp_dir, home_dir};
+        }
+    }
+    target_os = "uefi" => {
+        mod uefi;
+        use uefi as imp;
+    }
+    target_family = "unix" => {
+        mod unix;
+        use unix as imp;
+    }
+    target_os = "wasi" => {
+        mod wasi;
+        #[expect(dead_code)]
+        mod unsupported;
+        mod imp {
+            pub use super::wasi::{getcwd, chdir, temp_dir};
+            pub use super::unsupported::{current_exe, SplitPaths, split_paths, JoinPathsError, join_paths, home_dir};
+        }
+    }
+    target_os = "windows" => {
+        mod windows;
+        use windows as imp;
+    }
+    _ => {
+        mod unsupported;
+        use unsupported as imp;
+    }
+}
+
+pub use imp::{
+    JoinPathsError, SplitPaths, chdir, current_exe, getcwd, home_dir, join_paths, split_paths,
+    temp_dir,
+};

library/std/src/sys/paths/motor.rs

@@ -0,0 +1,20 @@
+use crate::io;
+use crate::os::motor::ffi::OsStrExt;
+use crate::path::{self, PathBuf};
+use crate::sys::pal::map_motor_error;
+
+pub fn getcwd() -> io::Result<PathBuf> {
+    moto_rt::fs::getcwd().map(PathBuf::from).map_err(map_motor_error)
+}
+
+pub fn chdir(path: &path::Path) -> io::Result<()> {
+    moto_rt::fs::chdir(path.as_os_str().as_str()).map_err(map_motor_error)
+}
+
+pub fn current_exe() -> io::Result<PathBuf> {
+    moto_rt::process::current_exe().map(PathBuf::from).map_err(map_motor_error)
+}
+
+pub fn temp_dir() -> PathBuf {
+    PathBuf::from(moto_rt::fs::TEMP_DIR)
+}

library/std/src/sys/paths/sgx.rs

@@ -0,0 +1,7 @@
+use crate::io;
+use crate::path::Path;
+use crate::sys::pal::sgx_ineffective;
+
+pub fn chdir(_: &Path) -> io::Result<()> {
+    sgx_ineffective(())
+}

library/std/src/sys/paths/uefi.rs

@@ -1,9 +1,9 @@
 use r_efi::efi::protocols::{device_path, loaded_image_device_path};
 
-use super::{helpers, unsupported_err};
 use crate::ffi::{OsStr, OsString};
 use crate::os::uefi::ffi::{OsStrExt, OsStringExt};
 use crate::path::{self, PathBuf};
+use crate::sys::pal::{helpers, unsupported_err};
 use crate::{fmt, io};
 
 const PATHS_SEP: u16 = b';' as u16;
@@ -115,7 +115,7 @@ pub fn current_exe() -> io::Result<PathBuf> {
 }
 
 pub fn temp_dir() -> PathBuf {
-    panic!("no filesystem on this platform")
+    panic!("UEFI doesn't have a dedicated temp directory")
 }
 
 pub fn home_dir() -> Option<PathBuf> {

library/std/src/sys/paths/unix.rs

@@ -7,8 +7,8 @@
 use crate::ffi::{CStr, OsStr, OsString};
 use crate::os::unix::prelude::*;
 use crate::path::{self, PathBuf};
-use crate::sys::cvt;
 use crate::sys::helpers::run_path_with_cstr;
+use crate::sys::pal::cvt;
 use crate::{fmt, io, iter, mem, ptr, slice, str};
 
 const PATH_SEPARATOR: u8 = b':';
@@ -47,7 +47,7 @@ pub fn getcwd() -> io::Result<PathBuf> {
 
 #[cfg(target_os = "espidf")]
 pub fn chdir(_p: &path::Path) -> io::Result<()> {
-    super::unsupported::unsupported()
+    crate::sys::pal::unsupported::unsupported()
 }
 
 #[cfg(not(target_os = "espidf"))]
@@ -372,7 +372,7 @@ pub fn current_exe() -> io::Result<PathBuf> {
 
 #[cfg(any(target_os = "espidf", target_os = "horizon", target_os = "vita"))]
 pub fn current_exe() -> io::Result<PathBuf> {
-    super::unsupported::unsupported()
+    crate::sys::pal::unsupported::unsupported()
 }
 
 #[cfg(target_os = "fuchsia")]

library/std/src/sys/paths/unsupported.rs

@@ -1,7 +1,7 @@
-use super::unsupported;
 use crate::ffi::{OsStr, OsString};
 use crate::marker::PhantomData;
 use crate::path::{self, PathBuf};
+use crate::sys::pal::unsupported;
 use crate::{fmt, io};
 
 pub fn getcwd() -> io::Result<PathBuf> {

library/std/src/sys/paths/wasi.rs

@@ -1,12 +1,10 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
-use crate::ffi::{CStr, OsStr, OsString};
-use crate::marker::PhantomData;
+use crate::ffi::{CStr, OsString};
+use crate::io;
 use crate::os::wasi::prelude::*;
 use crate::path::{self, PathBuf};
 use crate::sys::helpers::run_path_with_cstr;
-use crate::sys::unsupported;
-use crate::{fmt, io};
 
 pub fn getcwd() -> io::Result<PathBuf> {
     let mut buf = Vec::with_capacity(512);
@@ -42,46 +40,6 @@ pub fn chdir(p: &path::Path) -> io::Result<()> {
     }
 }
 
-pub struct SplitPaths<'a>(!, PhantomData<&'a ()>);
-
-pub fn split_paths(_unparsed: &OsStr) -> SplitPaths<'_> {
-    panic!("unsupported")
-}
-
-impl<'a> Iterator for SplitPaths<'a> {
-    type Item = PathBuf;
-    fn next(&mut self) -> Option<PathBuf> {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct JoinPathsError;
-
-pub fn join_paths<I, T>(_paths: I) -> Result<OsString, JoinPathsError>
-where
-    I: Iterator<Item = T>,
-    T: AsRef<OsStr>,
-{
-    Err(JoinPathsError)
-}
-
-impl fmt::Display for JoinPathsError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        "not supported on wasm yet".fmt(f)
-    }
-}
-
-impl crate::error::Error for JoinPathsError {}
-
-pub fn current_exe() -> io::Result<PathBuf> {
-    unsupported()
-}
-
 pub fn temp_dir() -> PathBuf {
-    panic!("no filesystem on wasm")
-}
-
-pub fn home_dir() -> Option<PathBuf> {
-    None
+    panic!("not supported by WASI yet")
 }

library/std/src/sys/paths/windows.rs

@@ -2,17 +2,13 @@
 
 #![allow(nonstandard_style)]
 
-#[cfg(test)]
-mod tests;
-
-use super::api;
-#[cfg(not(target_vendor = "uwp"))]
-use super::api::WinError;
 use crate::ffi::{OsStr, OsString};
 use crate::os::windows::ffi::EncodeWide;
 use crate::os::windows::prelude::*;
 use crate::path::{self, PathBuf};
-use crate::sys::pal::{c, cvt};
+#[cfg(not(target_vendor = "uwp"))]
+use crate::sys::pal::api::WinError;
+use crate::sys::pal::{api, c, cvt, fill_utf16_buf, os2path};
 use crate::{fmt, io, ptr};
 
 pub struct SplitPaths<'a> {
@@ -56,11 +52,7 @@ fn next(&mut self) -> Option<PathBuf> {
             }
         }
 
-        if !must_yield && in_progress.is_empty() {
-            None
-        } else {
-            Some(super::os2path(&in_progress))
-        }
+        if !must_yield && in_progress.is_empty() { None } else { Some(os2path(&in_progress)) }
     }
 }
 
@@ -104,14 +96,11 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 impl crate::error::Error for JoinPathsError {}
 
 pub fn current_exe() -> io::Result<PathBuf> {
-    super::fill_utf16_buf(
-        |buf, sz| unsafe { c::GetModuleFileNameW(ptr::null_mut(), buf, sz) },
-        super::os2path,
-    )
+    fill_utf16_buf(|buf, sz| unsafe { c::GetModuleFileNameW(ptr::null_mut(), buf, sz) }, os2path)
 }
 
 pub fn getcwd() -> io::Result<PathBuf> {
-    super::fill_utf16_buf(|buf, sz| unsafe { c::GetCurrentDirectoryW(sz, buf) }, super::os2path)
+    fill_utf16_buf(|buf, sz| unsafe { c::GetCurrentDirectoryW(sz, buf) }, os2path)
 }
 
 pub fn chdir(p: &path::Path) -> io::Result<()> {
@@ -123,7 +112,7 @@ pub fn chdir(p: &path::Path) -> io::Result<()> {
 }
 
 pub fn temp_dir() -> PathBuf {
-    super::fill_utf16_buf(|buf, sz| unsafe { c::GetTempPath2W(sz, buf) }, super::os2path).unwrap()
+    fill_utf16_buf(|buf, sz| unsafe { c::GetTempPath2W(sz, buf) }, os2path).unwrap()
 }
 
 #[cfg(all(not(target_vendor = "uwp"), not(target_vendor = "win7")))]
@@ -132,7 +121,7 @@ fn home_dir_crt() -> Option<PathBuf> {
         // Defined in processthreadsapi.h.
         const CURRENT_PROCESS_TOKEN: usize = -4_isize as usize;
 
-        super::fill_utf16_buf(
+        fill_utf16_buf(
             |buf, mut sz| {
                 // GetUserProfileDirectoryW does not quite use the usual protocol for
                 // negotiating the buffer size, so we have to translate.
@@ -146,7 +135,7 @@ fn home_dir_crt() -> Option<PathBuf> {
                     _ => sz - 1, // sz includes the null terminator
                 }
             },
-            super::os2path,
+            os2path,
         )
         .ok()
     }
@@ -163,7 +152,7 @@ fn home_dir_crt() -> Option<PathBuf> {
             return None;
         }
         let _handle = Handle::from_raw_handle(token);
-        super::fill_utf16_buf(
+        fill_utf16_buf(
             |buf, mut sz| {
                 match c::GetUserProfileDirectoryW(token, buf, &mut sz) {
                     0 if api::get_last_error() != WinError::INSUFFICIENT_BUFFER => 0,
@@ -171,7 +160,7 @@ fn home_dir_crt() -> Option<PathBuf> {
                     _ => sz - 1, // sz includes the null terminator
                 }
             },
-            super::os2path,
+            os2path,
         )
         .ok()
     }