Support allocating 4GB of memory (#452)

* Support allocating 4GB of memory

* Support 32bit archs as well

* Feedback

* Update core/src/vmem.rs

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "wasmi"
-version = "0.13.0"
+version = "0.13.1"
 edition = "2021"
 authors = ["Parity Technologies <[email protected]>", "Nikolay Volf <[email protected]>", "Svyatoslav Nikolsky <[email protected]>", "Sergey Pepyakin <[email protected]>"]
 license = "MIT/Apache-2.0"

core/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "wasmi_core"
-version = "0.2.0"
+version = "0.2.1"
 edition = "2021"
 authors = ["Parity Technologies <[email protected]>"]
 license = "MIT/Apache-2.0"

core/src/vmem.rs

@@ -54,8 +54,18 @@ impl Debug for VirtualMemory {
 }
 
 impl VirtualMemory {
-    /// The maximum allocation size for a `wasmi` virtual memory.
-    const MAX_ALLOCATION_SIZE: usize = u32::MAX as usize;
+    /// The maximum allocation size for a `wasmi` virtual memory on 16-bit.
+    #[cfg(target_pointer_width = "16")]
+    const MAX_ALLOCATION_SIZE: usize =
+        compile_error!("16-bit architectures are current unsupported by wasmi");
+
+    /// The maximum allocation size for a `wasmi` virtual memory on 32-bit.
+    #[cfg(target_pointer_width = "32")]
+    const MAX_ALLOCATION_SIZE: usize = i32::MAX as usize + 1; // 2GB
+
+    /// The maximum allocation size for a `wasmi` virtual memory on 64-bit.
+    #[cfg(target_pointer_width = "64")]
+    const MAX_ALLOCATION_SIZE: usize = u32::MAX as usize + 1; // 4GB
 
     /// Create a new virtual memory allocation.
     ///

src/memory/mmap_bytebuf.rs

@@ -23,7 +23,8 @@ impl ByteBuf {
     /// In this implementation we won't reallocate the virtually allocated
     /// buffer and instead simply adjust the `len` field of the `ByteBuf`
     /// wrapper in order to efficiently grow the virtual memory.
-    const ALLOCATION_SIZE: usize = u32::MAX as usize;
+    const ALLOCATION_SIZE: usize =
+        validation::LINEAR_MEMORY_MAX_PAGES as usize * super::LINEAR_MEMORY_PAGE_SIZE.0;
 
     /// Creates a new byte buffer with the given initial length.
     pub fn new(len: usize) -> Result<Self, String> {
@@ -96,4 +97,10 @@ mod tests {
         let mut byte_buf = ByteBuf::new(100).unwrap();
         assert!(byte_buf.realloc(ByteBuf::ALLOCATION_SIZE + 1).is_err());
     }
+
+    #[test]
+    fn allocate_maximum_number_of_pages() {
+        let mut byte_buf = ByteBuf::new(100).unwrap();
+        byte_buf.realloc(ByteBuf::ALLOCATION_SIZE).unwrap();
+    }
 }