6 files changed, 90 insertions, 10 deletions
diff --git a/library/std/src/sys/unix/fd.rs b/library/std/src/sys/unix/fd.rs
index 30812dabb4e..dbaa3c33e2e 100644
--- a/library/std/src/sys/unix/fd.rs
+++ b/library/std/src/sys/unix/fd.rs
@@ -4,7 +4,7 @@
 mod tests;
 
 use crate::cmp;
-use crate::io::{self, IoSlice, IoSliceMut, Read, ReadBuf};
+use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, Read};
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
 use crate::sys::cvt;
 use crate::sys_common::{AsInner, FromInner, IntoInner};
@@ -131,20 +131,19 @@ impl FileDesc {
         }
     }
 
-    pub fn read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
+    pub fn read_buf(&self, mut cursor: BorrowedCursor<'_>) -> io::Result<()> {
         let ret = cvt(unsafe {
             libc::read(
                 self.as_raw_fd(),
-                buf.unfilled_mut().as_mut_ptr() as *mut libc::c_void,
-                cmp::min(buf.remaining(), READ_LIMIT),
+                cursor.as_mut().as_mut_ptr() as *mut libc::c_void,
+                cmp::min(cursor.capacity(), READ_LIMIT),
             )
         })?;
 
         // Safety: `ret` bytes were written to the initialized portion of the buffer
         unsafe {
-            buf.assume_init(ret as usize);
+            cursor.advance(ret as usize);
         }
-        buf.add_filled(ret as usize);
         Ok(())
     }
 
diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs
index f38d2fd3d70..cc347e3586a 100644
--- a/library/std/src/sys/unix/fs.rs
+++ b/library/std/src/sys/unix/fs.rs
@@ -2,7 +2,7 @@ use crate::os::unix::prelude::*;
 
 use crate::ffi::{CStr, CString, OsStr, OsString};
 use crate::fmt;
-use crate::io::{self, Error, IoSlice, IoSliceMut, ReadBuf, SeekFrom};
+use crate::io::{self, BorrowedCursor, Error, IoSlice, IoSliceMut, SeekFrom};
 use crate::mem;
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd};
 use crate::path::{Path, PathBuf};
@@ -1037,8 +1037,8 @@ impl File {
         self.0.read_at(buf, offset)
     }
 
-    pub fn read_buf(&self, buf: &mut ReadBuf<'_>) -> io::Result<()> {
-        self.0.read_buf(buf)
+    pub fn read_buf(&self, cursor: BorrowedCursor<'_>) -> io::Result<()> {
+        self.0.read_buf(cursor)
     }
 
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
diff --git a/library/std/src/sys/unix/net.rs b/library/std/src/sys/unix/net.rs
index 462a45b01ab..b84bf8f9264 100644
--- a/library/std/src/sys/unix/net.rs
+++ b/library/std/src/sys/unix/net.rs
@@ -393,6 +393,17 @@ impl Socket {
     }
 
     #[cfg(any(target_os = "android", target_os = "linux",))]
+    pub fn set_quickack(&self, quickack: bool) -> io::Result<()> {
+        setsockopt(self, libc::IPPROTO_TCP, libc::TCP_QUICKACK, quickack as c_int)
+    }
+
+    #[cfg(any(target_os = "android", target_os = "linux",))]
+    pub fn quickack(&self) -> io::Result<bool> {
+        let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_QUICKACK)?;
+        Ok(raw != 0)
+    }
+
+    #[cfg(any(target_os = "android", target_os = "linux",))]
     pub fn set_passcred(&self, passcred: bool) -> io::Result<()> {
         setsockopt(self, libc::SOL_SOCKET, libc::SO_PASSCRED, passcred as libc::c_int)
     }
@@ -427,6 +438,17 @@ impl Socket {
         self.0.set_nonblocking(nonblocking)
     }
 
+    #[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "openbsd"))]
+    pub fn set_mark(&self, mark: u32) -> io::Result<()> {
+        #[cfg(target_os = "linux")]
+        let option = libc::SO_MARK;
+        #[cfg(target_os = "freebsd")]
+        let option = libc::SO_USER_COOKIE;
+        #[cfg(target_os = "openbsd")]
+        let option = libc::SO_RTABLE;
+        setsockopt(self, libc::SOL_SOCKET, option, mark as libc::c_int)
+    }
+
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
         let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
         if raw == 0 { Ok(None) } else { Ok(Some(io::Error::from_raw_os_error(raw as i32))) }
diff --git a/library/std/src/sys/unix/process/process_common.rs b/library/std/src/sys/unix/process/process_common.rs
index 6985f1d7830..2834ee0ace8 100644
--- a/library/std/src/sys/unix/process/process_common.rs
+++ b/library/std/src/sys/unix/process/process_common.rs
@@ -92,6 +92,7 @@ pub struct Command {
     argv: Argv,
     env: CommandEnv,
 
+    program_kind: ProgramKind,
     cwd: Option<CString>,
     uid: Option<uid_t>,
     gid: Option<gid_t>,
@@ -148,15 +149,40 @@ pub enum Stdio {
     Fd(FileDesc),
 }
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum ProgramKind {
+    /// A program that would be looked up on the PATH (e.g. `ls`)
+    PathLookup,
+    /// A relative path (e.g. `my-dir/foo`, `../foo`, `./foo`)
+    Relative,
+    /// An absolute path.
+    Absolute,
+}
+
+impl ProgramKind {
+    fn new(program: &OsStr) -> Self {
+        if program.bytes().starts_with(b"/") {
+            Self::Absolute
+        } else if program.bytes().contains(&b'/') {
+            // If the program has more than one component in it, it is a relative path.
+            Self::Relative
+        } else {
+            Self::PathLookup
+        }
+    }
+}
+
 impl Command {
     #[cfg(not(target_os = "linux"))]
     pub fn new(program: &OsStr) -> Command {
         let mut saw_nul = false;
+        let program_kind = ProgramKind::new(program.as_ref());
         let program = os2c(program, &mut saw_nul);
         Command {
             argv: Argv(vec![program.as_ptr(), ptr::null()]),
             args: vec![program.clone()],
             program,
+            program_kind,
             env: Default::default(),
             cwd: None,
             uid: None,
@@ -174,11 +200,13 @@ impl Command {
     #[cfg(target_os = "linux")]
     pub fn new(program: &OsStr) -> Command {
         let mut saw_nul = false;
+        let program_kind = ProgramKind::new(program.as_ref());
         let program = os2c(program, &mut saw_nul);
         Command {
             argv: Argv(vec![program.as_ptr(), ptr::null()]),
             args: vec![program.clone()],
             program,
+            program_kind,
             env: Default::default(),
             cwd: None,
             uid: None,
@@ -254,6 +282,11 @@ impl Command {
         OsStr::from_bytes(self.program.as_bytes())
     }
 
+    #[allow(dead_code)]
+    pub fn get_program_kind(&self) -> ProgramKind {
+        self.program_kind
+    }
+
     pub fn get_args(&self) -> CommandArgs<'_> {
         let mut iter = self.args.iter();
         iter.next();
diff --git a/library/std/src/sys/unix/process/process_common/tests.rs b/library/std/src/sys/unix/process/process_common/tests.rs
index 1956b3692a7..d176b3401c0 100644
--- a/library/std/src/sys/unix/process/process_common/tests.rs
+++ b/library/std/src/sys/unix/process/process_common/tests.rs
@@ -122,3 +122,27 @@ fn test_process_group_no_posix_spawn() {
         t!(cat.wait());
     }
 }
+
+#[test]
+fn test_program_kind() {
+    let vectors = &[
+        ("foo", ProgramKind::PathLookup),
+        ("foo.out", ProgramKind::PathLookup),
+        ("./foo", ProgramKind::Relative),
+        ("../foo", ProgramKind::Relative),
+        ("dir/foo", ProgramKind::Relative),
+        // Note that paths on Unix can't contain / in them, so this is actually the directory "fo\\"
+        // followed by the file "o".
+        ("fo\\/o", ProgramKind::Relative),
+        ("/foo", ProgramKind::Absolute),
+        ("/dir/../foo", ProgramKind::Absolute),
+    ];
+
+    for (program, expected_kind) in vectors {
+        assert_eq!(
+            ProgramKind::new(program.as_ref()),
+            *expected_kind,
+            "actual != expected program kind for input {program}",
+        );
+    }
+}
diff --git a/library/std/src/sys/unix/process/process_unix.rs b/library/std/src/sys/unix/process/process_unix.rs
index 75bb92437fd..26ae6281771 100644
--- a/library/std/src/sys/unix/process/process_unix.rs
+++ b/library/std/src/sys/unix/process/process_unix.rs
@@ -453,7 +453,9 @@ impl Command {
                     // successfully launch the program, but erroneously return
                     // ENOENT when used with posix_spawn_file_actions_addchdir_np
                     // which was introduced in macOS 10.15.
-                    return Ok(None);
+                    if self.get_program_kind() == ProgramKind::Relative {
+                        return Ok(None);
+                    }
                 }
                 match posix_spawn_file_actions_addchdir_np.get() {
                     Some(f) => Some((f, cwd)),