push the error types conversion all the way through

crates/wasi-c2/src/error.rs

@@ -21,6 +21,9 @@ pub enum ErrorKind {
     /// Errno::Inval: Invalid argument
     #[error("Inval: Invalid argument")]
     Inval,
+    /// Errno::Io: I/O error
+    #[error("Io: I/O error")]
+    Io,
     /// Errno::Nametoolong: Filename too long
     #[error("Nametoolong: Filename too long")]
     Nametoolong,
@@ -50,6 +53,7 @@ pub trait ErrorExt {
     fn exist() -> Self;
     fn illegal_byte_sequence() -> Self;
     fn invalid_argument() -> Self;
+    fn io() -> Self;
     fn name_too_long() -> Self;
     fn not_dir() -> Self;
     fn not_supported() -> Self;
@@ -75,6 +79,9 @@ impl ErrorExt for Error {
     fn invalid_argument() -> Self {
         ErrorKind::Inval.into()
     }
+    fn io() -> Self {
+        ErrorKind::Io.into()
+    }
     fn name_too_long() -> Self {
         ErrorKind::Nametoolong.into()
     }

crates/wasi-c2/src/snapshots/preview_1.rs

@@ -79,6 +79,7 @@ impl From<ErrorKind> for types::Errno {
             ErrorKind::Exist => Errno::Exist,
             ErrorKind::Ilseq => Errno::Ilseq,
             ErrorKind::Inval => Errno::Inval,
+            ErrorKind::Io => Errno::Io,
             ErrorKind::Nametoolong => Errno::Nametoolong,
             ErrorKind::Notdir => Errno::Notdir,
             ErrorKind::Notsup => Errno::Notsup,
@@ -141,9 +142,15 @@ impl TryFrom<std::io::Error> for types::Errno {
                 libc::EOVERFLOW => Ok(types::Errno::Overflow),
                 libc::EILSEQ => Ok(types::Errno::Ilseq),
                 libc::ENOTSUP => Ok(types::Errno::Notsup),
-                _ => Err(anyhow!(err).context("Unknown raw OS error")),
+                code => Err(anyhow!(err).context(format!("Unknown raw OS error: {}", code))),
+            },
+            None => match err.kind() {
+                std::io::ErrorKind::NotFound => Ok(types::Errno::Noent),
+                std::io::ErrorKind::PermissionDenied => Ok(types::Errno::Perm),
+                std::io::ErrorKind::AlreadyExists => Ok(types::Errno::Exist),
+                std::io::ErrorKind::InvalidInput => Ok(types::Errno::Ilseq),
+                k => Err(anyhow!(err).context(format!("No raw OS error. Unhandled kind: {:?}", k))),
             },
-            None => Err(anyhow!(err).context("No raw OS error")),
         }
     }
 }