From 4a41d36c528c66dfb0a22c1c02cebf9d80018ea5 Mon Sep 17 00:00:00 2001
From: vms <michail.vms@gmail.com>
Date: Sun, 25 Apr 2021 01:04:23 +0300
Subject: [PATCH] return error if allocate returns 0

---
 crates/it-lilo/src/lowerer/error.rs         | 3 +++
 crates/it-lilo/src/lowerer/memory_writer.rs | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/crates/it-lilo/src/lowerer/error.rs b/crates/it-lilo/src/lowerer/error.rs
index 6d1d501..f57437c 100644
--- a/crates/it-lilo/src/lowerer/error.rs
+++ b/crates/it-lilo/src/lowerer/error.rs
@@ -20,6 +20,9 @@ use thiserror::Error as ThisError;
 
 #[derive(Debug, ThisError)]
 pub enum LoError {
+    #[error("Allocator of Wasm module returns 0 which means that it's out of memory")]
+    AllocateWasInvalid,
+
     #[error("{0}")]
     AllocatableError(#[from] AllocatableError),
 
diff --git a/crates/it-lilo/src/lowerer/memory_writer.rs b/crates/it-lilo/src/lowerer/memory_writer.rs
index cfad04e..c5c2e7d 100644
--- a/crates/it-lilo/src/lowerer/memory_writer.rs
+++ b/crates/it-lilo/src/lowerer/memory_writer.rs
@@ -21,6 +21,7 @@ use crate::traits::DEFAULT_MEMORY_INDEX;
 use crate::utils::type_tag_form_itype;
 
 use std::cell::Cell;
+use crate::lowerer::LoError;
 
 pub struct MemoryWriter<'i, R: Allocatable> {
     heap_manager: &'i R,
@@ -54,6 +55,10 @@ impl<'i, A: Allocatable> MemoryWriter<'i, A> {
 
     pub fn sequential_writer(&self, size: u32, type_tag: u32) -> LoResult<SequentialWriter> {
         let offset = self.heap_manager.allocate(size, type_tag)?;
+        if offset == 0 {
+            return Err(LoError::AllocateWasInvalid);
+        }
+
         let new_mem_slice = self.heap_manager.memory_slice(DEFAULT_MEMORY_INDEX)?;
         self.memory.set(new_mem_slice);