Makes errno fully derivable

src/kernel/src/errno.rs

@@ -1,9 +1,8 @@
 use std::convert::Infallible;
 use std::error::Error;
 use std::num::NonZeroI32;
-
-use macros::Errno;
 use thiserror::Error;
+
 // This file contains errno used in a PS4 system. The value of each errno must be the same as the
 // PS4.
 

src/kernel/src/fs/dev/vnode.rs

@@ -7,7 +7,6 @@ use crate::fs::{
 };
 use crate::process::VThread;
 use macros::Errno;
-use std::num::NonZeroI32;
 use std::sync::Arc;
 use thiserror::Error;
 

src/kernel/src/fs/host/mod.rs

@@ -180,8 +180,10 @@ enum MountError {
 #[derive(Debug, Error, Errno)]
 enum GetVnodeError {
     #[error("cannot open the specified file")]
+    #[errno(EIO)]
     OpenFileFailed(#[source] std::io::Error),
 
     #[error("cannot determine file type")]
+    #[errno(EIO)]
     GetFileTypeFailed(#[source] std::io::Error),
 }

src/kernel/src/fs/mod.rs

@@ -1131,7 +1131,7 @@ pub enum OpenError {
 #[derive(Debug, Error, Errno)]
 pub enum WriteError {}
 
-#[derive(Debug, Error)]
+#[derive(Debug, Error, Errno)]
 pub enum IoctlError {
     #[error("Couldn't get file")]
     FailedToGetFile(#[from] GetFileError),

src/kernel/src/fs/tmp/mod.rs

@@ -2,7 +2,7 @@ use self::node::{AllocNodeError, Node, Nodes};
 use super::{Filesystem, FsConfig, Mount, MountFlags, MountOpts, MountSource, VPathBuf, Vnode};
 use crate::errno::{Errno, EINVAL};
 use crate::ucred::{Ucred, Uid};
-use std::num::NonZeroI32;
+use macros::Errno;
 use std::sync::atomic::AtomicI32;
 use std::sync::Arc;
 use thiserror::Error;

src/macros/src/errno.rs

@@ -1,6 +1,6 @@
 use proc_macro2::{Ident, TokenStream};
 use quote::quote;
-use syn::{punctuated::Punctuated, Fields, ItemEnum, Meta, Token, Variant};
+use syn::{punctuated::Punctuated, Fields, ItemEnum, Meta, Token, Variant, Index};
 
 pub fn transform(arg: ItemEnum) -> syn::Result<TokenStream> {
     let enum_name = &arg.ident;
@@ -12,7 +12,7 @@ pub fn transform(arg: ItemEnum) -> syn::Result<TokenStream> {
         .collect::<Result<Vec<_>, _>>()?;
 
     if arms.is_empty() {
-         Ok(quote!(
+        Ok(quote!(
             impl Errno for #enum_name {
                 fn errno(&self) -> std::num::NonZeroI32 {
                     match *self {}
@@ -105,14 +105,13 @@ fn process_variant(variant: &Variant, enum_name: &Ident) -> syn::Result<TokenStr
             return match pos {
                 Some(pos) => {
                     let variant_name = &variant.ident;
-
                     // The field at index `pos` is the one we are interested in
 
-                    let inner = (0..fields.len())
-                        .map(|i| if i == pos { quote!(e) } else { quote!(_) })
-                        .fold(quote!(), |acc, c| quote!(#acc #c));
+                    // We have to use this. otherwise the macro would expand to something like
+                    // `{ 0usize: e, .. }` which is accepted, but only temporarily
+                    let index = Index::from(pos);
 
-                    Ok(quote!(#enum_name::#variant_name ( #inner ) => e.errno(),))
+                    Ok(quote!(#enum_name::#variant_name { #index: e, .. } => e.errno(),))
                 }
                 None => Err(syn::Error::new_spanned(
                     variant,