Replace use of the libc by the rustix crate

In the interest of reducing 3rd-party dependencies and maintaining
control over our code, I would not only like to restore our old polling
code in favour of the polling crate (inko-lang#344), but also switch to using
rustix. The benefit of using rustix is that at least on Linux we can
avoid libc calls. While this may result in a performance improvement,
it's really more about slowly reducing our dependencies on 3rd-party
libraries, including libc. The API might also be a bit more pleasant
to use compared to using the libc crate directly.

Changelog: changed

Cargo.toml

@@ -1,5 +1,6 @@
 [workspace]
 members = ["ast", "inko", "compiler", "rt"]
+resolver = "2"
 
 [profile.release]
 panic = "abort"

rt/Cargo.toml

@@ -19,6 +19,7 @@ rand = { version = "^0.8", features = ["default", "small_rng"] }
 polling = "^2.8"
 unicode-segmentation = "^1.8"
 backtrace = "^0.3"
+rustix = { version = "^0.38", features = ["fs", "mm", "param", "process", "net", "std", "time"], default-features = false }
 
 [dependencies.socket2]
 version = "^0.5"

rt/src/memory_map.rs

@@ -1,7 +1,6 @@
 use crate::page::{multiple_of_page_size, page_size};
-use libc::{
-    c_int, mmap, mprotect, munmap, MAP_ANON, MAP_FAILED, MAP_PRIVATE,
-    PROT_NONE, PROT_READ, PROT_WRITE,
+use rustix::mm::{
+    mmap_anonymous, mprotect, munmap, MapFlags, MprotectFlags, ProtFlags,
 };
 use std::io::{Error, Result as IoResult};
 use std::ptr::null_mut;
@@ -12,16 +11,16 @@ pub(crate) struct MemoryMap {
     pub(crate) len: usize,
 }
 
-fn mmap_options(_stack: bool) -> c_int {
-    let base = MAP_PRIVATE | MAP_ANON;
+fn mmap_options(_stack: bool) -> MapFlags {
+    let base = MapFlags::PRIVATE;
 
     #[cfg(any(
         target_os = "linux",
         target_os = "freebsd",
         target_os = "openbsd"
     ))]
     if _stack {
-        return base | libc::MAP_STACK;
+        return base | MapFlags::STACK;
     }
 
     base
@@ -32,34 +31,44 @@ impl MemoryMap {
         let size = multiple_of_page_size(size);
         let opts = mmap_options(stack);
 
-        let ptr = unsafe {
-            mmap(null_mut(), size, PROT_READ | PROT_WRITE, opts, -1, 0)
+        let res = unsafe {
+            mmap_anonymous(
+                null_mut(),
+                size,
+                ProtFlags::READ | ProtFlags::WRITE,
+                opts,
+            )
         };
 
-        if ptr == MAP_FAILED {
-            panic!("mmap(2) failed: {}", Error::last_os_error());
+        match res {
+            Ok(ptr) => MemoryMap { ptr: ptr as *mut u8, len: size },
+            Err(e) => panic!(
+                "mmap(2) failed: {}",
+                Error::from_raw_os_error(e.raw_os_error())
+            ),
         }
-
-        MemoryMap { ptr: ptr as *mut u8, len: size }
     }
 
     pub(crate) fn protect(&mut self, start: usize) -> IoResult<()> {
         let res = unsafe {
-            mprotect(self.ptr.add(start) as _, page_size(), PROT_NONE)
+            mprotect(
+                self.ptr.add(start) as _,
+                page_size(),
+                MprotectFlags::empty(),
+            )
         };
 
-        if res == 0 {
-            Ok(())
-        } else {
-            Err(Error::last_os_error())
+        match res {
+            Ok(_) => Ok(()),
+            Err(e) => Err(Error::from_raw_os_error(e.raw_os_error())),
         }
     }
 }
 
 impl Drop for MemoryMap {
     fn drop(&mut self) {
         unsafe {
-            munmap(self.ptr as _, self.len);
+            let _ = munmap(self.ptr as _, self.len);
         }
     }
 }

rt/src/page.rs

@@ -1,16 +1,11 @@
-use libc::{sysconf, _SC_PAGESIZE};
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 static PAGE_SIZE: AtomicUsize = AtomicUsize::new(0);
 
-fn page_size_raw() -> usize {
-    unsafe { sysconf(_SC_PAGESIZE) as usize }
-}
-
 pub(crate) fn page_size() -> usize {
     match PAGE_SIZE.load(Ordering::Relaxed) {
         0 => {
-            let size = page_size_raw();
+            let size = rustix::param::page_size();
 
             PAGE_SIZE.store(size, Ordering::Relaxed);
             size

rt/src/runtime.rs

@@ -27,8 +27,10 @@ use std::io::{stdout, Write as _};
 use std::process::exit as rust_exit;
 use std::thread;
 
-#[cfg(unix)]
-fn ignore_sigpipe() {
+const SIGPIPE: i32 = 13;
+const SIG_IGN: usize = 1;
+
+extern "C" {
     // Broken pipe errors default to terminating the entire program, making it
     // impossible to handle such errors. This is especially problematic for
     // sockets, as writing to a socket closed on the other end would terminate
@@ -37,14 +39,7 @@ fn ignore_sigpipe() {
     // While Rust handles this for us when compiling an executable, it doesn't
     // do so when compiling it to a static library and linking it to our
     // generated code, so we must handle this ourselves.
-    unsafe {
-        libc::signal(libc::SIGPIPE, libc::SIG_IGN);
-    }
-}
-
-#[cfg(not(unix))]
-fn ignore_sigpipe() {
-    // Not needed on these platforms
+    fn signal(sig: i32, handler: usize) -> usize;
 }
 
 #[no_mangle]
@@ -65,7 +60,7 @@ pub unsafe extern "system" fn inko_runtime_start(
     class: ClassPointer,
     method: NativeAsyncMethod,
 ) {
-    ignore_sigpipe();
+    signal(SIGPIPE, SIG_IGN);
     (*runtime).start(class, method);
     flush_stdout();
 }

rt/src/runtime/time.rs

@@ -1,19 +1,11 @@
 use crate::mem::Float;
 use crate::state::State;
+use rustix::time;
 use std::mem::MaybeUninit;
 
 fn utc() -> f64 {
-    unsafe {
-        let mut ts = MaybeUninit::uninit();
-
-        if libc::clock_gettime(libc::CLOCK_REALTIME, ts.as_mut_ptr()) != 0 {
-            panic!("clock_gettime() failed");
-        }
-
-        let ts = ts.assume_init();
-
-        ts.tv_sec as f64 + (ts.tv_nsec as f64 / 1_000_000_000.0)
-    }
+    let ts = time::clock_gettime(time::ClockId::Realtime);
+    ts.tv_sec as f64 + (ts.tv_nsec as f64 / 1_000_000_000.0)
 }
 
 fn offset() -> i64 {
@@ -22,16 +14,7 @@ fn offset() -> i64 {
             fn tzset();
         }
 
-        let ts = {
-            let mut ts = MaybeUninit::uninit();
-
-            if libc::clock_gettime(libc::CLOCK_REALTIME, ts.as_mut_ptr()) != 0 {
-                panic!("clock_gettime() failed");
-            }
-
-            ts.assume_init()
-        };
-
+        let ts = time::clock_gettime(time::ClockId::Realtime);
         let mut tm = MaybeUninit::uninit();
 
         // localtime_r() doesn't necessarily call tzset() for us.

rt/src/scheduler/mod.rs

@@ -5,19 +5,14 @@ pub mod timeouts;
 use std::thread::available_parallelism;
 
 #[cfg(target_os = "linux")]
-use {
-    libc::{cpu_set_t, sched_setaffinity, CPU_SET},
-    std::mem::{size_of, zeroed},
-};
+use rustix::process::{sched_setaffinity, CpuSet, Pid};
 
 #[cfg(target_os = "linux")]
 pub(crate) fn pin_thread_to_core(core: usize) {
-    unsafe {
-        let mut set: cpu_set_t = zeroed();
+    let mut set = CpuSet::new();
+    set.set(core);
 
-        CPU_SET(core, &mut set);
-        sched_setaffinity(0, size_of::<cpu_set_t>(), &set);
-    }
+    let _ = sched_setaffinity(Pid::from_raw(0), &set);
 }
 
 #[cfg(not(target_os = "linux"))]

rt/src/socket.rs

@@ -4,7 +4,7 @@ use crate::network_poller::Interest;
 use crate::process::ProcessPointer;
 use crate::socket::socket_address::SocketAddress;
 use crate::state::State;
-use libc::{EINPROGRESS, EISCONN};
+use rustix::io::Errno;
 use socket2::{Domain, SockAddr, Socket as RawSocket, Type};
 use std::io::{self, Read};
 use std::mem::transmute;
@@ -197,7 +197,8 @@ impl Socket {
             Ok(_) => Ok(()),
             Err(ref e)
                 if e.kind() == io::ErrorKind::WouldBlock
-                    || e.raw_os_error() == Some(EINPROGRESS) =>
+                    || e.raw_os_error()
+                        == Some(Errno::INPROGRESS.raw_os_error()) =>
             {
                 if let Ok(Some(err)) = self.inner.take_error() {
                     // When performing a connect(), the error returned may be
@@ -208,8 +209,10 @@ impl Socket {
 
                 Err(io::Error::from(io::ErrorKind::WouldBlock))
             }
-            Err(ref e) if e.raw_os_error() == Some(EISCONN) => {
-                // We may run into an EISCONN if a previous connect(2) attempt
+            Err(ref e)
+                if e.raw_os_error() == Some(Errno::ISCONN.raw_os_error()) =>
+            {
+                // We may run into an ISCONN if a previous connect(2) attempt
                 // would block. In this case we can just continue.
                 Ok(())
             }