You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
74 lines
2.9 KiB
74 lines
2.9 KiB
//! An example of how to interact with wasm memory.
|
|
//!
|
|
//! Here a small wasm module is used to show how memory is initialized, how to
|
|
//! read and write memory through the `Memory` object, and how wasm functions
|
|
//! can trap when dealing with out-of-bounds addresses.
|
|
|
|
// You can execute this example with `cargo run --example example`
|
|
|
|
use anyhow::Result;
|
|
use wasmtime::*;
|
|
|
|
fn main() -> Result<()> {
|
|
// Create our `store_fn` context and then compile a module and create an
|
|
// instance from the compiled module all in one go.
|
|
let mut store: Store<()> = Store::default();
|
|
let module = Module::from_file(store.engine(), "examples/memory.wat")?;
|
|
let instance = Instance::new(&mut store, &module, &[])?;
|
|
|
|
// load_fn up our exports from the instance
|
|
let memory = instance
|
|
.get_memory(&mut store, "memory")
|
|
.ok_or(anyhow::format_err!("failed to find `memory` export"))?;
|
|
let size = instance.get_typed_func::<(), i32, _>(&mut store, "size")?;
|
|
let load_fn = instance.get_typed_func::<i32, i32, _>(&mut store, "load")?;
|
|
let store_fn = instance.get_typed_func::<(i32, i32), (), _>(&mut store, "store")?;
|
|
|
|
println!("Checking memory...");
|
|
assert_eq!(memory.size(&store), 2);
|
|
assert_eq!(memory.data_size(&store), 0x20000);
|
|
assert_eq!(memory.data_mut(&mut store)[0], 0);
|
|
assert_eq!(memory.data_mut(&mut store)[0x1000], 1);
|
|
assert_eq!(memory.data_mut(&mut store)[0x1003], 4);
|
|
|
|
assert_eq!(size.call(&mut store, ())?, 2);
|
|
assert_eq!(load_fn.call(&mut store, 0)?, 0);
|
|
assert_eq!(load_fn.call(&mut store, 0x1000)?, 1);
|
|
assert_eq!(load_fn.call(&mut store, 0x1003)?, 4);
|
|
assert_eq!(load_fn.call(&mut store, 0x1ffff)?, 0);
|
|
assert!(load_fn.call(&mut store, 0x20000).is_err()); // out of bounds trap
|
|
|
|
println!("Mutating memory...");
|
|
memory.data_mut(&mut store)[0x1003] = 5;
|
|
|
|
store_fn.call(&mut store, (0x1002, 6))?;
|
|
assert!(store_fn.call(&mut store, (0x20000, 0)).is_err()); // out of bounds trap
|
|
|
|
assert_eq!(memory.data(&store)[0x1002], 6);
|
|
assert_eq!(memory.data(&store)[0x1003], 5);
|
|
assert_eq!(load_fn.call(&mut store, 0x1002)?, 6);
|
|
assert_eq!(load_fn.call(&mut store, 0x1003)?, 5);
|
|
|
|
// Grow memory.
|
|
println!("Growing memory...");
|
|
memory.grow(&mut store, 1)?;
|
|
assert_eq!(memory.size(&store), 3);
|
|
assert_eq!(memory.data_size(&store), 0x30000);
|
|
|
|
assert_eq!(load_fn.call(&mut store, 0x20000)?, 0);
|
|
store_fn.call(&mut store, (0x20000, 0))?;
|
|
assert!(load_fn.call(&mut store, 0x30000).is_err());
|
|
assert!(store_fn.call(&mut store, (0x30000, 0)).is_err());
|
|
|
|
assert!(memory.grow(&mut store, 1).is_err());
|
|
assert!(memory.grow(&mut store, 0).is_ok());
|
|
|
|
println!("Creating stand-alone memory...");
|
|
let memorytype = MemoryType::new(5, Some(5));
|
|
let memory2 = Memory::new(&mut store, memorytype)?;
|
|
assert_eq!(memory2.size(&store), 5);
|
|
assert!(memory2.grow(&mut store, 1).is_err());
|
|
assert!(memory2.grow(&mut store, 0).is_ok());
|
|
|
|
Ok(())
|
|
}
|
|
|