Rollup merge of #127480 - biabbas:vxworks, r=workingjubilee

Fix build failure on vxworks #127084

PR to address issue #127084 .
1. Skip `reset_segpipe` for vxworks
2. Return unimplemented error for vxworks from settimes and lchown
3. Temporarily skip dirfd for vxworks
4. Add allow unused unsafe on read_at and write_at functions in unix/fs.rs
5. Using cfg disable ON_BROKEN_PIPE_FLAG_USED and on_broken_pipe_flag_used() for vxworks
6. Remove old crate::syscommon::thread::min_stack() reference from process_vxworks.rs and update to set stack size of rtpthread

Thank you.

library/std/src/os/unix/fs.rs

@@ -1064,7 +1064,7 @@ pub fn lchown<P: AsRef<Path>>(dir: P, uid: Option<u32>, gid: Option<u32>) -> io:
 /// }
 /// ```
 #[stable(feature = "unix_chroot", since = "1.56.0")]
-#[cfg(not(any(target_os = "fuchsia", target_os = "vxworks")))]
+#[cfg(not(target_os = "fuchsia"))]
 pub fn chroot<P: AsRef<Path>>(dir: P) -> io::Result<()> {
     sys::fs::chroot(dir.as_ref())
 }

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

@@ -125,6 +125,7 @@ impl FileDesc {
         (&mut me).read_to_end(buf)
     }
 
+    #[cfg_attr(target_os = "vxworks", allow(unused_unsafe))]
     pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
         #[cfg(not(any(
             all(target_os = "linux", not(target_env = "musl")),
@@ -318,6 +319,7 @@ impl FileDesc {
         cfg!(not(any(target_os = "espidf", target_os = "horizon", target_os = "vita")))
     }
 
+    #[cfg_attr(target_os = "vxworks", allow(unused_unsafe))]
     pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
         #[cfg(not(any(
             all(target_os = "linux", not(target_env = "musl")),

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

@@ -857,6 +857,7 @@ impl Drop for Dir {
             target_os = "espidf",
             target_os = "fuchsia",
             target_os = "horizon",
+            target_os = "vxworks",
         )))]
         {
             let fd = unsafe { libc::dirfd(self.0) };
@@ -1313,7 +1314,12 @@ impl File {
     }
 
     pub fn set_times(&self, times: FileTimes) -> io::Result<()> {
-        #[cfg(not(any(target_os = "redox", target_os = "espidf", target_os = "horizon")))]
+        #[cfg(not(any(
+            target_os = "redox",
+            target_os = "espidf",
+            target_os = "horizon",
+            target_os = "vxworks"
+        )))]
         let to_timespec = |time: Option<SystemTime>| match time {
             Some(time) if let Some(ts) = time.t.to_timespec() => Ok(ts),
             Some(time) if time > crate::sys::time::UNIX_EPOCH => Err(io::const_io_error!(
@@ -1327,10 +1333,11 @@ impl File {
             None => Ok(libc::timespec { tv_sec: 0, tv_nsec: libc::UTIME_OMIT as _ }),
         };
         cfg_if::cfg_if! {
-            if #[cfg(any(target_os = "redox", target_os = "espidf", target_os = "horizon"))] {
+            if #[cfg(any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "vxworks"))] {
                 // Redox doesn't appear to support `UTIME_OMIT`.
                 // ESP-IDF and HorizonOS do not support `futimens` at all and the behavior for those OS is therefore
                 // the same as for Redox.
+                // `futimens` and `UTIME_OMIT` are a work in progress for vxworks.
                 let _ = times;
                 Err(io::const_io_error!(
                     io::ErrorKind::Unsupported,
@@ -1962,18 +1969,31 @@ pub fn fchown(fd: c_int, uid: u32, gid: u32) -> io::Result<()> {
     Ok(())
 }
 
+#[cfg(not(target_os = "vxworks"))]
 pub fn lchown(path: &Path, uid: u32, gid: u32) -> io::Result<()> {
     run_path_with_cstr(path, &|path| {
         cvt(unsafe { libc::lchown(path.as_ptr(), uid as libc::uid_t, gid as libc::gid_t) })
             .map(|_| ())
     })
 }
 
+#[cfg(target_os = "vxworks")]
+pub fn lchown(path: &Path, uid: u32, gid: u32) -> io::Result<()> {
+    let (_, _, _) = (path, uid, gid);
+    Err(io::const_io_error!(io::ErrorKind::Unsupported, "lchown not supported by vxworks"))
+}
+
 #[cfg(not(any(target_os = "fuchsia", target_os = "vxworks")))]
 pub fn chroot(dir: &Path) -> io::Result<()> {
     run_path_with_cstr(dir, &|dir| cvt(unsafe { libc::chroot(dir.as_ptr()) }).map(|_| ()))
 }
 
+#[cfg(target_os = "vxworks")]
+pub fn chroot(dir: &Path) -> io::Result<()> {
+    let _ = dir;
+    Err(io::const_io_error!(io::ErrorKind::Unsupported, "chroot not supported by vxworks"))
+}
+
 pub use remove_dir_impl::remove_dir_all;
 
 // Fallback for REDOX, ESP-ID, Horizon, Vita, Vxworks and Miri

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

@@ -164,6 +164,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
             target_os = "emscripten",
             target_os = "fuchsia",
             target_os = "horizon",
+            target_os = "vxworks",
             // Unikraft's `signal` implementation is currently broken:
             // https://github.com/unikraft/lib-musl/issues/57
             target_vendor = "unikraft",
@@ -209,6 +210,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
     target_os = "emscripten",
     target_os = "fuchsia",
     target_os = "horizon",
+    target_os = "vxworks",
 )))]
 static ON_BROKEN_PIPE_FLAG_USED: crate::sync::atomic::AtomicBool =
     crate::sync::atomic::AtomicBool::new(false);
@@ -218,6 +220,7 @@ static ON_BROKEN_PIPE_FLAG_USED: crate::sync::atomic::AtomicBool =
     target_os = "emscripten",
     target_os = "fuchsia",
     target_os = "horizon",
+    target_os = "vxworks",
 )))]
 pub(crate) fn on_broken_pipe_flag_used() -> bool {
     ON_BROKEN_PIPE_FLAG_USED.load(crate::sync::atomic::Ordering::Relaxed)

library/std/src/sys/pal/unix/process/process_vxworks.rs

@@ -3,8 +3,8 @@ use crate::io::{self, ErrorKind};
 use crate::num::NonZero;
 use crate::sys;
 use crate::sys::cvt;
+use crate::sys::pal::unix::thread;
 use crate::sys::process::process_common::*;
-use crate::sys_common::thread;
 use libc::RTP_ID;
 use libc::{self, c_char, c_int};
 
@@ -68,7 +68,12 @@ impl Command {
                 .as_ref()
                 .map(|c| c.as_ptr())
                 .unwrap_or_else(|| *sys::os::environ() as *const _);
-            let stack_size = thread::min_stack();
+            let stack_size = crate::cmp::max(
+                crate::env::var_os("RUST_MIN_STACK")
+                    .and_then(|s| s.to_str().and_then(|s| s.parse().ok()))
+                    .unwrap_or(thread::DEFAULT_MIN_STACK_SIZE),
+                libc::PTHREAD_STACK_MIN,
+            );
 
             // ensure that access to the environment is synchronized
             let _lock = sys::os::env_read_lock();