Draft out IntDatatype in wiggle-generate (bytecodealliance#15)

* Draft out IntDatatype in wiggle-generate

This commit drafts out basic layout for `IntDatatype` structure in
`wiggle`. As it currently stands, an `Int` type is represented as
a one-element tuple struct much like `FlagDatatype`, however, with
this difference that we do not perform any checks on the input
underlying representation since any value for the prescribed type
is legal.

* Finish drafting IntDatatype support in wiggle

This commit adds necessary marshal stubs to properly pass `IntDatatype`
in and out of interface functions. It also adds a basic proptest.

crates/generate/src/funcs.rs

@@ -154,6 +154,7 @@ fn marshal_arg(
     match &*tref.type_() {
         witx::Type::Enum(_e) => try_into_conversion,
         witx::Type::Flags(_f) => try_into_conversion,
+        witx::Type::Int(_i) => try_into_conversion,
         witx::Type::Builtin(b) => match b {
             witx::BuiltinType::U8 | witx::BuiltinType::U16 | witx::BuiltinType::Char8 => {
                 try_into_conversion
@@ -359,7 +360,7 @@ where
             | witx::BuiltinType::Char8 => write_val_to_ptr,
             witx::BuiltinType::String => unimplemented!("string types"),
         },
-        witx::Type::Enum(_) | witx::Type::Flags(_) => write_val_to_ptr,
+        witx::Type::Enum(_) | witx::Type::Flags(_) | witx::Type::Int(_) => write_val_to_ptr,
         _ => unimplemented!("marshal result"),
     }
 }

crates/generate/src/names.rs

@@ -86,6 +86,10 @@ impl Names {
         format_ident!("{}", id.as_str().to_shouty_snake_case())
     }
 
+    pub fn int_member(&self, id: &Id) -> Ident {
+        format_ident!("{}", id.as_str().to_shouty_snake_case())
+    }
+
     pub fn struct_member(&self, id: &Id) -> Ident {
         format_ident!("{}", id.as_str().to_snake_case())
     }

crates/generate/src/types.rs

@@ -10,7 +10,7 @@ pub fn define_datatype(names: &Names, namedtype: &witx::NamedType) -> TokenStrea
         witx::TypeRef::Name(alias_to) => define_alias(names, &namedtype.name, &alias_to),
         witx::TypeRef::Value(v) => match &**v {
             witx::Type::Enum(e) => define_enum(names, &namedtype.name, &e),
-            witx::Type::Int(_) => unimplemented!("int types"),
+            witx::Type::Int(i) => define_int(names, &namedtype.name, &i),
             witx::Type::Flags(f) => define_flags(names, &namedtype.name, &f),
             witx::Type::Struct(s) => {
                 if struct_is_copy(s) {
@@ -46,6 +46,92 @@ fn define_alias(names: &Names, name: &witx::Id, to: &witx::NamedType) -> TokenSt
     }
 }
 
+fn define_int(names: &Names, name: &witx::Id, i: &witx::IntDatatype) -> TokenStream {
+    let ident = names.type_(&name);
+    let repr = int_repr_tokens(i.repr);
+    let abi_repr = atom_token(match i.repr {
+        witx::IntRepr::U8 | witx::IntRepr::U16 | witx::IntRepr::U32 => witx::AtomType::I32,
+        witx::IntRepr::U64 => witx::AtomType::I64,
+    });
+    let consts = i
+        .consts
+        .iter()
+        .map(|r#const| {
+            let const_ident = names.int_member(&r#const.name);
+            let value = r#const.value;
+            quote!(pub const #const_ident: #ident = #ident(#value))
+        })
+        .collect::<Vec<_>>();
+
+    quote! {
+        #[repr(transparent)]
+        #[derive(Copy, Clone, Debug, ::std::hash::Hash, Eq, PartialEq)]
+        pub struct #ident(#repr);
+
+        impl #ident {
+            #(#consts;)*
+        }
+
+        impl ::std::convert::TryFrom<#repr> for #ident {
+            type Error = wiggle_runtime::GuestError;
+            fn try_from(value: #repr) -> Result<Self, wiggle_runtime::GuestError> {
+                Ok(#ident(value))
+            }
+        }
+
+        impl ::std::convert::TryFrom<#abi_repr> for #ident {
+            type Error = wiggle_runtime::GuestError;
+            fn try_from(value: #abi_repr) -> Result<#ident, wiggle_runtime::GuestError> {
+                #ident::try_from(value as #repr)
+            }
+        }
+
+        impl From<#ident> for #repr {
+            fn from(e: #ident) -> #repr {
+                e.0
+            }
+        }
+
+        impl From<#ident> for #abi_repr {
+            fn from(e: #ident) -> #abi_repr {
+                #repr::from(e) as #abi_repr
+            }
+        }
+
+        impl wiggle_runtime::GuestType for #ident {
+            fn size() -> u32 {
+                ::std::mem::size_of::<#repr>() as u32
+            }
+
+            fn align() -> u32 {
+                ::std::mem::align_of::<#repr>() as u32
+            }
+
+            fn name() -> String {
+                stringify!(#ident).to_owned()
+            }
+
+            fn validate<'a>(location: &wiggle_runtime::GuestPtr<'a, #ident>) -> Result<(), wiggle_runtime::GuestError> {
+                use ::std::convert::TryFrom;
+                let raw: #repr = unsafe { (location.as_raw() as *const #repr).read() };
+                let _ = #ident::try_from(raw)?;
+                Ok(())
+            }
+        }
+
+        impl wiggle_runtime::GuestTypeCopy for #ident {}
+        impl<'a> wiggle_runtime::GuestTypeClone<'a> for #ident {
+            fn read_from_guest(location: &wiggle_runtime::GuestPtr<#ident>) -> Result<#ident, wiggle_runtime::GuestError> {
+                Ok(*location.as_ref()?)
+            }
+            fn write_to_guest(&self, location: &wiggle_runtime::GuestPtrMut<#ident>) {
+                let val: #repr = #repr::from(*self);
+                unsafe { (location.as_raw() as *mut #repr).write(val) };
+            }
+        }
+    }
+}
+
 fn define_flags(names: &Names, name: &witx::Id, f: &witx::FlagsDatatype) -> TokenStream {
     let ident = names.type_(&name);
     let repr = int_repr_tokens(f.repr);

tests/main.rs

@@ -143,6 +143,15 @@ impl foo::Foo for WasiCtx {
         println!("a_string='{}'", as_str);
         Ok(as_str.len() as u32)
     }
+
+    fn cookie_cutter(&mut self, init_cookie: types::Cookie) -> Result<types::Bool, types::Errno> {
+        let res = if init_cookie == types::Cookie::START {
+            types::Bool::True
+        } else {
+            types::Bool::False
+        };
+        Ok(res)
+    }
 }
 // Errno is used as a first return value in the functions above, therefore
 // it must implement GuestErrorType with type Context = WasiCtx.
@@ -958,3 +967,62 @@ proptest! {
         e.test()
     }
 }
+
+fn cookie_strat() -> impl Strategy<Value = types::Cookie> {
+    (0..std::u64::MAX)
+        .prop_map(|x| types::Cookie::try_from(x).expect("within range of cookie"))
+        .boxed()
+}
+
+#[derive(Debug)]
+struct CookieCutterExercise {
+    cookie: types::Cookie,
+    return_ptr_loc: MemArea,
+}
+
+impl CookieCutterExercise {
+    pub fn strat() -> BoxedStrategy<Self> {
+        (cookie_strat(), HostMemory::mem_area_strat(4))
+            .prop_map(|(cookie, return_ptr_loc)| Self {
+                cookie,
+                return_ptr_loc,
+            })
+            .boxed()
+    }
+
+    pub fn test(&self) {
+        let mut ctx = WasiCtx::new();
+        let mut host_memory = HostMemory::new();
+        let mut guest_memory = GuestMemory::new(host_memory.as_mut_ptr(), host_memory.len() as u32);
+
+        let res = foo::cookie_cutter(
+            &mut ctx,
+            &mut guest_memory,
+            self.cookie.into(),
+            self.return_ptr_loc.ptr as i32,
+        );
+        assert_eq!(res, types::Errno::Ok.into(), "cookie cutter errno");
+
+        let is_cookie_start = *guest_memory
+            .ptr::<types::Bool>(self.return_ptr_loc.ptr)
+            .expect("ptr to returned Bool")
+            .as_ref()
+            .expect("deref to Bool value");
+
+        assert_eq!(
+            if is_cookie_start == types::Bool::True {
+                true
+            } else {
+                false
+            },
+            self.cookie == types::Cookie::START,
+            "returned Bool should test if input was Cookie::START",
+        );
+    }
+}
+proptest! {
+    #[test]
+    fn cookie_cutter(e in CookieCutterExercise::strat()) {
+        e.test()
+    }
+}

tests/test.witx

@@ -18,6 +18,15 @@
     $awd
     $suv))
 
+(typename $cookie
+  (int u64
+    (const $start 0)))
+
+(typename $bool
+  (enum u8
+    $false
+    $true))
+
 (typename $pair_ints
   (struct
     (field $first s32)
@@ -77,4 +86,9 @@
     (result $error $errno)
     (result $total_bytes u32)
   )
+  (@interface func (export "cookie_cutter")
+    (param $init_cookie $cookie)
+    (result $error $errno)
+    (result $is_start $bool)
+  )
 )