Add crumbles::Mmap::set_len and adapt piecrust memory behavior

crumbles/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `Mmap::set_len` function
+
 ## [0.1.1] - 2023-09-07
 
 ### Fixed

crumbles/src/lib.rs

@@ -42,6 +42,7 @@
 #![deny(clippy::pedantic)]
 
 use std::{
+    cmp,
     collections::BTreeMap,
     fs::File,
     mem::{self, MaybeUninit},
@@ -304,6 +305,11 @@ impl Mmap {
                 )
             })
     }
+
+    /// Sets the length of the memory mapping to the given number of bytes.
+    pub fn set_len(&mut self, len: u32) {
+        self.0.set_len(len);
+    }
 }
 
 impl AsRef<[u8]> for Mmap {
@@ -465,8 +471,15 @@ impl MmapInner {
 
     unsafe fn set_dirty(&mut self, page_num: usize) -> io::Result<()> {
         let start_addr = self.bytes.as_ptr() as usize;
-
         let page_offset = page_num * PAGE_SIZE;
+
+        if page_offset >= self.bytes.len() {
+            return Err(io::Error::new(
+                io::ErrorKind::PermissionDenied,
+                "Out of bounds write",
+            ));
+        }
+
         let page_addr = start_addr + page_offset;
 
         if libc::mprotect(page_addr as _, PAGE_SIZE, PROT_READ | PROT_WRITE)
@@ -544,6 +557,15 @@ impl MmapInner {
         Ok(())
     }
 
+    fn set_len(&mut self, len: u32) {
+        let ptr = self.bytes.as_mut_ptr();
+
+        let len = len as usize + PAGE_SIZE;
+        let len = cmp::min(MEM_SIZE, len);
+
+        unsafe { self.bytes = slice::from_raw_parts_mut(ptr, len) };
+    }
+
     fn last_snapshot(&self) -> &Snapshot {
         self.snapshots
             .last()

piecrust/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## Changed
+
+- Change to use `crumbles::Mmap::set_len` on growing memory
+
 ## [0.9.1] - 2023-09-07
 
 ### Changed

piecrust/src/store/memory.rs

@@ -5,11 +5,11 @@
 // Copyright (c) DUSK NETWORK. All rights reserved.
 
 use std::fs::OpenOptions;
-use std::io;
 use std::ops::{Deref, DerefMut};
 use std::path::Path;
 use std::ptr::NonNull;
 use std::sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard};
+use std::{cmp, io};
 
 use crumbles::{Mmap, PAGE_SIZE};
 use wasmer::WASM_MAX_PAGES;
@@ -27,7 +27,6 @@ pub const MAX_MEM_SIZE: usize = MAX_PAGES * PAGE_SIZE;
 #[derive(Debug)]
 pub(crate) struct MemoryInner {
     pub(crate) mmap: Mmap,
-    pub(crate) current_len: usize,
     def: VMMemoryDefinition,
     init: bool,
 }
@@ -42,15 +41,16 @@ impl Memory {
     pub(crate) fn new() -> io::Result<Self> {
         let mut mmap = Mmap::new()?;
 
+        mmap.set_len(MIN_MEM_SIZE as u32);
+
         let def = VMMemoryDefinition {
             base: mmap.as_mut_ptr(),
-            current_length: MAX_MEM_SIZE,
+            current_length: MIN_MEM_SIZE + PAGE_SIZE,
         };
 
         Ok(Self {
             inner: Arc::new(RwLock::new(MemoryInner {
                 mmap,
-                current_len: MIN_MEM_SIZE,
                 def,
                 init: false,
             })),
@@ -72,15 +72,16 @@ impl Memory {
             }))?
         };
 
+        mmap.set_len(len as u32);
+
         let def = VMMemoryDefinition {
             base: mmap.as_mut_ptr(),
-            current_length: MAX_MEM_SIZE,
+            current_length: cmp::min(len + PAGE_SIZE, MAX_MEM_SIZE),
         };
 
         Ok(Self {
             inner: Arc::new(RwLock::new(MemoryInner {
                 mmap,
-                current_len: len,
                 def,
                 init: true,
             })),
@@ -156,21 +157,21 @@ impl LinearMemory for Memory {
     }
 
     fn size(&self) -> Pages {
-        let pages = self.read().inner.current_len / PAGE_SIZE;
+        let pages = self.read().len() / PAGE_SIZE;
         Pages(pages as u32)
     }
 
     fn style(&self) -> MemoryStyle {
         MemoryStyle::Static {
             bound: Pages(MAX_PAGES as u32),
-            offset_guard_size: PAGE_SIZE as u64,
+            offset_guard_size: 0,
         }
     }
 
     fn grow(&mut self, delta: Pages) -> Result<Pages, MemoryError> {
         let mut memory = self.write();
 
-        let current_len = memory.inner.current_len;
+        let current_len = memory.len();
         let new_len = current_len + delta.0 as usize * PAGE_SIZE;
 
         if new_len > MAX_PAGES * PAGE_SIZE {
@@ -180,7 +181,13 @@ impl LinearMemory for Memory {
             });
         }
 
-        memory.inner.current_len = new_len;
+        memory.set_len(new_len as u32);
+
+        memory.inner.def = VMMemoryDefinition {
+            base: memory.as_mut_ptr(),
+            current_length: cmp::min(new_len + PAGE_SIZE, MAX_MEM_SIZE),
+        };
+
         Ok(Pages((new_len / PAGE_SIZE) as u32))
     }
 

piecrust/src/store/tree.rs

@@ -66,7 +66,7 @@ impl ContractIndex {
         let memory = memory.read();
         let memory_inner = memory.inner;
 
-        element.len = memory_inner.current_len;
+        element.len = memory_inner.mmap.len();
 
         for (dirty_page, _, page_offset) in memory_inner.mmap.dirty_pages() {
             element.offsets.insert(page_offset);