1 #![no_std]
2 
3 #[macro_use]
4 extern crate alloc;
5 
6 use alloc::string::ToString;
7 use anyhow::Result;
8 use core::ptr;
9 use wasmtime::{Engine, Instance, Linker, Module, Store};
10 
11 mod allocator;
12 mod panic;
13 
14 #[cfg(feature = "wasi")]
15 mod wasi;
16 
17 /// Entrypoint of this embedding.
18 ///
19 /// This takes a number of parameters which are the precompiled module AOT
20 /// images that are run for each of the various tests below. The first parameter
21 /// is also where to put an error string, if any, if anything fails.
22 #[unsafe(no_mangle)]
23 pub unsafe extern "C" fn run(
24     error_buf: *mut u8,
25     error_size: usize,
26     smoke_module: *const u8,
27     smoke_size: usize,
28     simple_add_module: *const u8,
29     simple_add_size: usize,
30     simple_host_fn_module: *const u8,
31     simple_host_fn_size: usize,
32 ) -> usize {
33     unsafe {
34         let buf = core::slice::from_raw_parts_mut(error_buf, error_size);
35         let smoke = core::slice::from_raw_parts(smoke_module, smoke_size);
36         let simple_add = core::slice::from_raw_parts(simple_add_module, simple_add_size);
37         let simple_host_fn =
38             core::slice::from_raw_parts(simple_host_fn_module, simple_host_fn_size);
39         match run_result(smoke, simple_add, simple_host_fn) {
40             Ok(()) => 0,
41             Err(e) => {
42                 let msg = format!("{e:?}");
43                 let len = buf.len().min(msg.len());
44                 buf[..len].copy_from_slice(&msg.as_bytes()[..len]);
45                 len
46             }
47         }
48     }
49 }
50 
51 fn run_result(
52     smoke_module: &[u8],
53     simple_add_module: &[u8],
54     simple_host_fn_module: &[u8],
55 ) -> Result<()> {
56     smoke(smoke_module)?;
57     simple_add(simple_add_module)?;
58     simple_host_fn(simple_host_fn_module)?;
59     Ok(())
60 }
61 
62 fn smoke(module: &[u8]) -> Result<()> {
63     let engine = Engine::default();
64     let module = match deserialize(&engine, module)? {
65         Some(module) => module,
66         None => return Ok(()),
67     };
68     Instance::new(&mut Store::new(&engine, ()), &module, &[])?;
69     Ok(())
70 }
71 
72 fn simple_add(module: &[u8]) -> Result<()> {
73     let engine = Engine::default();
74     let module = match deserialize(&engine, module)? {
75         Some(module) => module,
76         None => return Ok(()),
77     };
78     let mut store = Store::new(&engine, ());
79     let instance = Linker::new(&engine).instantiate(&mut store, &module)?;
80     let func = instance.get_typed_func::<(u32, u32), u32>(&mut store, "add")?;
81     assert_eq!(func.call(&mut store, (2, 3))?, 5);
82     Ok(())
83 }
84 
85 fn simple_host_fn(module: &[u8]) -> Result<()> {
86     let engine = Engine::default();
87     let module = match deserialize(&engine, module)? {
88         Some(module) => module,
89         None => return Ok(()),
90     };
91     let mut linker = Linker::<()>::new(&engine);
92     linker.func_wrap("host", "multiply", |a: u32, b: u32| a.saturating_mul(b))?;
93     let mut store = Store::new(&engine, ());
94     let instance = linker.instantiate(&mut store, &module)?;
95     let func = instance.get_typed_func::<(u32, u32, u32), u32>(&mut store, "add_and_mul")?;
96     assert_eq!(func.call(&mut store, (2, 3, 4))?, 10);
97     Ok(())
98 }
99 
100 fn deserialize(engine: &Engine, module: &[u8]) -> Result<Option<Module>> {
101     // NOTE: deserialize_raw avoids creating a copy of the module code.  See the
102     // safety notes before using in your embedding.
103     let memory_ptr = ptr::slice_from_raw_parts(module.as_ptr(), module.len());
104     let module_memory = ptr::NonNull::new(memory_ptr.cast_mut()).unwrap();
105     match unsafe { Module::deserialize_raw(engine, module_memory) } {
106         Ok(module) => Ok(Some(module)),
107         Err(e) => {
108             // Currently if custom signals/virtual memory are disabled then this
109             // example is expected to fail to load since loading native code
110             // requires virtual memory. In the future this will go away as when
111             // signals-based-traps is disabled then that means that the
112             // interpreter should be used which should work here.
113             if !cfg!(feature = "custom")
114                 && e.to_string()
115                     .contains("requires virtual memory to be enabled")
116             {
117                 Ok(None)
118             } else {
119                 Err(e)
120             }
121         }
122     }
123 }
124