Add support for illumos (#371)

With this commit, ipc-channel works and the full test suite passes on illumos.
I've also added a small amount of debug logging that was invaluable to me while
porting over ipc-channel to illumos.

I'm also happy to set up cross-compile CI, and if there's interest then I could
chat with folks at Oxide about providing resources for runtime CI as well.

Cargo.toml

@@ -38,7 +38,7 @@ rand = "0.8"
 serde = { version = "1.0", features = ["rc"] }
 uuid = { version = "1", features = ["v4"] }
 
-[target.'cfg(any(target_os = "linux", target_os = "openbsd", target_os = "freebsd"))'.dependencies]
+[target.'cfg(any(target_os = "linux", target_os = "openbsd", target_os = "freebsd", target_os = "illumos"))'.dependencies]
 mio = { version = "1.0", features = ["os-ext"] }
 tempfile = "3.4"
 

src/platform/mod.rs

@@ -9,12 +9,22 @@
 
 #[cfg(all(
     not(feature = "force-inprocess"),
-    any(target_os = "linux", target_os = "openbsd", target_os = "freebsd")
+    any(
+        target_os = "linux",
+        target_os = "openbsd",
+        target_os = "freebsd",
+        target_os = "illumos",
+    )
 ))]
 mod unix;
 #[cfg(all(
     not(feature = "force-inprocess"),
-    any(target_os = "linux", target_os = "openbsd", target_os = "freebsd")
+    any(
+        target_os = "linux",
+        target_os = "openbsd",
+        target_os = "freebsd",
+        target_os = "illumos",
+    )
 ))]
 mod os {
     pub use super::unix::*;

src/platform/unix/mod.rs

@@ -49,9 +49,9 @@ const MAX_FDS_IN_CMSG: u32 = 64;
 // Empirically, we have to deduct 32 bytes from that.
 const RESERVED_SIZE: usize = 32;
 
-#[cfg(target_os = "linux")]
+#[cfg(any(target_os = "linux", target_os = "illumos"))]
 const SOCK_FLAGS: c_int = libc::SOCK_CLOEXEC;
-#[cfg(not(target_os = "linux"))]
+#[cfg(not(any(target_os = "linux", target_os = "illumos")))]
 const SOCK_FLAGS: c_int = 0;
 
 #[cfg(target_os = "linux")]
@@ -130,9 +130,15 @@ pub struct OsIpcReceiver {
 impl Drop for OsIpcReceiver {
     fn drop(&mut self) {
         unsafe {
-            if self.fd.get() >= 0 {
-                let result = libc::close(self.fd.get());
-                assert!(thread::panicking() || result == 0);
+            let fd = self.fd.get();
+            if fd >= 0 {
+                let result = libc::close(fd);
+                assert!(
+                    thread::panicking() || result == 0,
+                    "closed receiver (fd: {}): {}",
+                    fd,
+                    UnixError::last(),
+                );
             }
         }
     }
@@ -778,7 +784,9 @@ impl BackingStore {
     pub unsafe fn map_file(&self, length: Option<size_t>) -> (*mut u8, size_t) {
         let length = length.unwrap_or_else(|| {
             let mut st = mem::MaybeUninit::uninit();
-            assert!(libc::fstat(self.fd, st.as_mut_ptr()) == 0);
+            if libc::fstat(self.fd, st.as_mut_ptr()) != 0 {
+                panic!("error stating fd {}: {}", self.fd, UnixError::last());
+            }
             st.assume_init().st_size as size_t
         });
         if length == 0 {