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     let buf = core::slice::from_raw_parts_mut(error_buf, error_size);
34     let smoke = core::slice::from_raw_parts(smoke_module, smoke_size);
35     let simple_add = core::slice::from_raw_parts(simple_add_module, simple_add_size);
36     let simple_host_fn = core::slice::from_raw_parts(simple_host_fn_module, simple_host_fn_size);
37     match run_result(smoke, simple_add, simple_host_fn) {
38         Ok(()) => 0,
39         Err(e) => {
40             let msg = format!("{e:?}");
41             let len = buf.len().min(msg.len());
42             buf[..len].copy_from_slice(&msg.as_bytes()[..len]);
43             len
44         }
45     }
46 }
47 
48 fn run_result(
49     smoke_module: &[u8],
50     simple_add_module: &[u8],
51     simple_host_fn_module: &[u8],
52 ) -> Result<()> {
53     smoke(smoke_module)?;
54     simple_add(simple_add_module)?;
55     simple_host_fn(simple_host_fn_module)?;
56     Ok(())
57 }
58 
59 fn smoke(module: &[u8]) -> Result<()> {
60     let engine = Engine::default();
61     let module = match deserialize(&engine, module)? {
62         Some(module) => module,
63         None => return Ok(()),
64     };
65     Instance::new(&mut Store::new(&engine, ()), &module, &[])?;
66     Ok(())
67 }
68 
69 fn simple_add(module: &[u8]) -> Result<()> {
70     let engine = Engine::default();
71     let module = match deserialize(&engine, module)? {
72         Some(module) => module,
73         None => return Ok(()),
74     };
75     let mut store = Store::new(&engine, ());
76     let instance = Linker::new(&engine).instantiate(&mut store, &module)?;
77     let func = instance.get_typed_func::<(u32, u32), u32>(&mut store, "add")?;
78     assert_eq!(func.call(&mut store, (2, 3))?, 5);
79     Ok(())
80 }
81 
82 fn simple_host_fn(module: &[u8]) -> Result<()> {
83     let engine = Engine::default();
84     let module = match deserialize(&engine, module)? {
85         Some(module) => module,
86         None => return Ok(()),
87     };
88     let mut linker = Linker::<()>::new(&engine);
89     linker.func_wrap("host", "multiply", |a: u32, b: u32| a.saturating_mul(b))?;
90     let mut store = Store::new(&engine, ());
91     let instance = linker.instantiate(&mut store, &module)?;
92     let func = instance.get_typed_func::<(u32, u32, u32), u32>(&mut store, "add_and_mul")?;
93     assert_eq!(func.call(&mut store, (2, 3, 4))?, 10);
94     Ok(())
95 }
96 
97 fn deserialize(engine: &Engine, module: &[u8]) -> Result<Option<Module>> {
98     // NOTE: deserialize_raw avoids creating a copy of the module code.  See the
99     // safety notes before using in your embedding.
100     let memory_ptr = ptr::slice_from_raw_parts(module.as_ptr(), module.len());
101     let module_memory = ptr::NonNull::new(memory_ptr.cast_mut()).unwrap();
102     match unsafe { Module::deserialize_raw(engine, module_memory) } {
103         Ok(module) => Ok(Some(module)),
104         Err(e) => {
105             // Currently if custom signals/virtual memory are disabled then this
106             // example is expected to fail to load since loading native code
107             // requires virtual memory. In the future this will go away as when
108             // signals-based-traps is disabled then that means that the
109             // interpreter should be used which should work here.
110             if !cfg!(feature = "custom")
111                 && e.to_string()
112                     .contains("requires virtual memory to be enabled")
113             {
114                 Ok(None)
115             } else {
116                 Err(e)
117             }
118         }
119     }
120 }
121