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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,165 @@ | ||
| use core::fmt::Debug; | ||
|
|
||
| use alloc::vec::Vec; | ||
|
|
||
| use crate::{ | ||
| core::reader::span::Span, read_constant_expression::read_constant_instructions, Error, Result, | ||
| }; | ||
|
|
||
| use super::RefType; | ||
|
|
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| #[derive(Clone)] | ||
| pub struct ElemType { | ||
| pub init: ElemItems, | ||
| pub mode: ElemMode, | ||
| } | ||
|
|
||
| impl Debug for ElemType { | ||
| fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { | ||
| write!( | ||
| f, | ||
| "ElemType {{\n\tinit: {:?},\n\tmode: {:?},\n\t#ty: {}\n}}", | ||
| self.init, | ||
| self.mode, | ||
| self.init.ty() | ||
| ) | ||
| } | ||
| } | ||
|
|
||
| impl ElemType { | ||
| pub fn ty(&self) -> RefType { | ||
| self.init.ty() | ||
| } | ||
| pub fn to_ref_type(&self) -> RefType { | ||
| match self.init { | ||
| ElemItems::Exprs(rref, _) => rref, | ||
| ElemItems::RefFuncs(_) => RefType::FuncRef, | ||
| } | ||
| } | ||
|
|
||
| pub fn read_from_wasm( | ||
| wasm: &mut crate::core::reader::WasmReader, | ||
| functions: &[usize], | ||
| referenced_functions: &mut alloc::collections::btree_set::BTreeSet<u32>, | ||
| tables_length: usize, | ||
| ) -> Result<Vec<Self>> { | ||
| use crate::core::reader::types::element::*; | ||
| use crate::RefType; | ||
| // https://webassembly.github.io/spec/core/binary/modules.html#element-section | ||
|
|
||
| wasm.read_vec(|wasm| { | ||
| let ty = wasm.read_var_u32().unwrap(); | ||
| // https://webassembly.github.io/spec/core/syntax/modules.html#element-segments | ||
| // https://webassembly.github.io/spec/core/binary/modules.html#element-section | ||
| // We can treat the ttype as a 3bit integer | ||
| // If it's not 3 bits I am not sure what to do | ||
| // bit 0 => diff between passive|declartive and active segment | ||
| // bit 1 => presence of an explicit table index for an active segment | ||
| // bit 2 => use of element type and element expressions instead of element kind and element indices | ||
| assert!(ty <= 0b111, "Element section is not encoded correctly. The type of this element is over 7 (0b111)"); | ||
| // decide if we should | ||
| let elem_mode = if ty & 0b001 == 0b001 { | ||
| if ty & 0b010 == 0b010 { | ||
| ElemMode::Declarative | ||
| } else { | ||
| ElemMode::Passive | ||
| } | ||
| } else { | ||
| let table_idx = if ty & 0b010 == 0b010 { | ||
| wasm.read_var_u32()? | ||
| } else { | ||
| 0 | ||
| }; | ||
| if tables_length <= table_idx as usize { | ||
| return Err(Error::UnknownTable); | ||
| } | ||
| let expr = read_constant_instructions(wasm, None, None, Some(&functions))?; | ||
|
|
||
| ElemMode::Active(ActiveElem { | ||
| table: table_idx, | ||
| offset: expr, | ||
| }) | ||
| }; | ||
| let use_of_el_ty_and_el_exprs = ty & 0b100 == 0b100; | ||
|
|
||
| let reftype_or_elemkind: Option<RefType> = match if ty & 0b011 != 0 { | ||
| if use_of_el_ty_and_el_exprs { | ||
| Some(wasm.read_u8()?) | ||
| } else { | ||
| let read = wasm.read_u8()?; | ||
| match read { | ||
| 0x00 => None, | ||
| _ => todo!("Only FuncRefs are allowed"), | ||
| } | ||
| } | ||
| } else { | ||
| None | ||
| } { | ||
| None => None, | ||
| Some(ty) => Some(RefType::from_byte(ty)?), | ||
| }; | ||
|
|
||
| match reftype_or_elemkind { | ||
| Some(rty) => trace!("REFTYPE: {}", rty), | ||
| None => { | ||
| trace!("REFTYPE NONE!") | ||
| } | ||
| }; | ||
|
|
||
| let items: ElemItems = if use_of_el_ty_and_el_exprs { | ||
| ElemItems::Exprs( | ||
| reftype_or_elemkind.unwrap_or(RefType::FuncRef), | ||
| wasm.read_vec(|w| read_constant_instructions(w, None, None, Some(&functions)))?, | ||
| ) | ||
| } else { | ||
| assert!(reftype_or_elemkind.is_none()); | ||
| ElemItems::RefFuncs(wasm.read_vec(|w| { | ||
| let offset = w.read_var_u32()?; | ||
| referenced_functions.insert(offset); | ||
| Ok(offset) | ||
| })?) | ||
| }; | ||
|
|
||
| let el = ElemType { | ||
| init: items, | ||
| mode: elem_mode, | ||
| }; | ||
|
|
||
| Ok(el) | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| /// Here we can't implement WasmReadable because we also want a mutable | ||
| /// reference to a BTreeSet<u32> (`referenced_functions`) | ||
| /// | ||
| /// This comes in handy later on when we are validating the actual code of | ||
| /// the functions so that we can make sure we are not referencing invalid functions | ||
| #[derive(Debug, Clone)] | ||
| pub enum ElemItems { | ||
| RefFuncs(Vec<u32>), | ||
| Exprs(RefType, Vec<Span>), | ||
| } | ||
|
|
||
| impl ElemItems { | ||
| pub fn ty(&self) -> RefType { | ||
| match self { | ||
| Self::RefFuncs(_) => RefType::FuncRef, | ||
| Self::Exprs(rty, _) => *rty, | ||
| } | ||
| } | ||
| } | ||
|
|
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| #[derive(Debug, Clone)] | ||
| pub enum ElemMode { | ||
| Passive, | ||
| Active(ActiveElem), | ||
| Declarative, | ||
| } | ||
|
|
||
| #[derive(Debug, Clone)] | ||
| pub struct ActiveElem { | ||
| pub table: u32, | ||
| pub offset: Span, | ||
| } |
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