Add the Verify mode (#726)

#46

---------

Co-authored-by: Zhou Fang <[email protected]>
Co-authored-by: Julien Cretin <[email protected]>

crates/interpreter/src/lib.rs

@@ -156,4 +156,4 @@ pub use module::Module;
 pub use syntax::{
     FuncType, GlobalType, ImportDesc, Limits, Mut, RefType, ResultType, TableType, ValType,
 };
-pub use valid::validate;
+pub use valid::prepare;

crates/interpreter/src/module.rs

@@ -20,7 +20,7 @@ use crate::parser::{SkipData, SkipElem};
 use crate::side_table::*;
 use crate::syntax::*;
 use crate::toctou::*;
-use crate::valid::validate;
+use crate::valid::prepare;
 use crate::*;
 
 /// Valid module.
@@ -52,7 +52,7 @@ impl ImportDesc {
 impl<'m> Module<'m> {
     /// Validates a WASM module in binary format.
     pub fn new(binary: &'m [u8]) -> Result<Self, Error> {
-        let side_table = validate(binary)?;
+        let side_table = prepare(binary)?;
         let mut module = unsafe { Self::new_unchecked(binary) };
         // TODO(dev/fast-interp): We should take a buffer as argument to write to.
         module.side_table = Box::leak(Box::new(side_table));

crates/interpreter/src/side_table.rs

@@ -18,39 +18,62 @@ use core::ops::Range;
 use crate::error::*;
 use crate::module::Parser;
 
-#[allow(dead_code)]
-pub struct SideTable<'m> {
-    indices: &'m [u16], // including 0 and the length of metadata_array
-    metadata: &'m [u16],
+pub struct SideTableView<'m> {
+    pub func_idx: usize,
+    pub indices: &'m [u16], // including 0 and the length of metadata_array
+    pub metadata: &'m [u16],
+    pub branch_table_view: Metadata<'m>,
 }
 
-#[allow(dead_code)]
-impl<'m> SideTable<'m> {
-    fn metadata(&self, func_idx: usize) -> Metadata<'m> {
+impl<'m> SideTableView<'m> {
+    pub fn new(parser: &mut crate::valid::Parser<'m>) -> Result<Self, Error> {
+        Ok(SideTableView {
+            func_idx: 0,
+            indices: parse_side_table_field(parser)?,
+            metadata: parse_side_table_field(parser)?,
+            branch_table_view: Default::default(),
+        })
+    }
+
+    pub fn metadata(&self, func_idx: usize) -> Metadata<'m> {
         Metadata(
             &self.metadata[self.indices[func_idx] as usize .. self.indices[func_idx + 1] as usize],
         )
     }
 }
 
-#[allow(dead_code)]
-#[derive(Copy, Clone)]
-struct Metadata<'m>(&'m [u16]);
+fn parse_u16(data: &[u8]) -> u16 {
+    bytemuck::pod_read_unaligned::<u16>(bytemuck::cast_slice(&data[0 .. 2]))
+}
+
+fn parse_side_table_field<'m>(parser: &mut crate::valid::Parser<'m>) -> Result<&'m [u16], Error> {
+    let len = parse_u16(parser.save()) as usize;
+    let parser = parser.split_at(len)?;
+    let bytes = parser.save().get(0 .. len * 2).unwrap();
+    Ok(bytemuck::cast_slice::<_, u16>(bytes))
+}
+
+#[derive(Default, Copy, Clone)]
+pub struct Metadata<'m>(&'m [u16]);
 
-#[allow(dead_code)]
 impl<'m> Metadata<'m> {
     pub fn type_idx(&self) -> usize {
         self.0[0] as usize
     }
 
+    #[allow(dead_code)]
     pub fn parser(&self, module: &'m [u8]) -> Parser<'m> {
-        unsafe { Parser::new(&module[self.read_u32(1) .. self.read_u32(3)]) }
+        unsafe { Parser::new(&module[self.parser_range()]) }
     }
 
     pub fn branch_table(&self) -> &[BranchTableEntry] {
         bytemuck::cast_slice(&self.0[5 ..])
     }
 
+    pub fn parser_range(&self) -> Range<usize> {
+        self.read_u32(1) .. self.read_u32(3)
+    }
+
     fn read_u32(&self, idx: usize) -> usize {
         bytemuck::pod_read_unaligned::<u32>(bytemuck::cast_slice(&self.0[idx .. idx + 2])) as usize
     }