windows nightly can give us filestat info

Cargo.lock

@@ -2368,9 +2368,11 @@ version = "0.21.0"
 dependencies = [
  "anyhow",
  "cap-std",
+ "cfg-if 1.0.0",
  "fs-set-times",
  "getrandom 0.2.0",
  "libc",
+ "rustc_version",
  "system-interface",
  "thiserror",
  "tracing",

crates/wasi-c2/Cargo.toml

@@ -11,6 +11,7 @@ readme = "README.md"
 edition = "2018"
 include = ["src/**/*", "LICENSE", "build.rs"]
 build = "build.rs"
+publish = false
 
 [dependencies]
 anyhow = "1.0"
@@ -22,6 +23,10 @@ tracing = "0.1.19"
 system-interface = "0.2"
 cap-std = "0.6"
 fs-set-times = "0.2.1"
+cfg-if = "1"
+
+[build-dependencies]
+rustc_version = "0.2"
 
 [badges]
 maintenance = { status = "actively-developed" }

crates/wasi-c2/build.rs

@@ -5,4 +5,14 @@ fn main() {
     let wasi = cwd.join("..").join("wasi-common").join("WASI");
     println!("cargo:wasi={}", wasi.display());
     println!("cargo:rustc-env=WASI_ROOT={}", wasi.display());
+
+    match rustc_version::version_meta()
+        .expect("query rustc release channel")
+        .channel
+    {
+        rustc_version::Channel::Nightly => {
+            println!("cargo:rustc-cfg=nightly");
+        }
+        _ => {}
+    }
 }

crates/wasi-c2/src/file.rs

@@ -1,4 +1,5 @@
 use crate::Error;
+use cfg_if::cfg_if;
 use fs_set_times::SetTimes;
 use std::ops::Deref;
 use system_interface::fs::FileIoExt;
@@ -193,14 +194,26 @@ impl WasiFile for cap_std::fs::File {
         Ok(())
     }
     fn get_filestat(&self) -> Result<Filestat, Error> {
-        // XXX cap-std does not expose every part of filestat
-        #![allow(unreachable_code, unused_variables)]
         let meta = self.metadata()?;
+        let (device_id, inode, nlink) = cfg_if! {
+            if #[cfg(unix)] {
+                use std::os::unix::fs::MetadataExt;
+                (meta.dev(), meta.ino(), meta.nlink())
+            } else if #[cfg(windows)] && #[cfg_attr(feature = "nightly")] {
+                use std::os::windows::fs::MetadataExt;
+                ( meta.volume_serial_number().unwrap_or(-1),
+                  meta.file_index().unwrap_or(-1),
+                  meta.number_of_links().unwrap_or(0),
+                )
+            } else {
+                (-1, -1, 0)
+            }
+        };
         Ok(Filestat {
-            device_id: todo!(),
-            inode: todo!(),
+            device_id,
+            inode,
             filetype: self.get_filetype()?,
-            nlink: todo!(),
+            nlink,
             size: meta.len(),
             atim: meta.accessed()?.into_std(),
             mtim: meta.modified()?.into_std(),