wasm3-provider 0.0.2

A wasm3 engine provider for the waPC host
Documentation 
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use std::sync::Arc;
use wapc::ModuleState;
use wasm3::CallContext;

pub(crate) fn host_call(
    ctx: &CallContext,
    bd_ptr: i32,
    bd_len: i32,
    ns_ptr: i32,
    ns_len: i32,
    op_ptr: i32,
    op_len: i32,
    ptr: i32,
    len: i32,
    host: Arc<ModuleState>,
) -> i32 {
    let vec = get_vec_from_memory(ctx, ptr, len);
    let bd_vec = get_vec_from_memory(ctx, bd_ptr, bd_len);
    let bd = ::std::str::from_utf8(&bd_vec).unwrap();
    let ns_vec = get_vec_from_memory(ctx, ns_ptr, ns_len);
    let ns = ::std::str::from_utf8(&ns_vec).unwrap();
    let op_vec = get_vec_from_memory(ctx, op_ptr, op_len);
    let op = ::std::str::from_utf8(&op_vec).unwrap();

    let result = host.do_host_call(bd, ns, op, &vec);
    if let Ok(r) = result {
        r
    } else {
        0
    }
}

pub(crate) fn guest_request(ctx: &CallContext, op_ptr: i32, ptr: i32, host: Arc<ModuleState>) {
    if let Some(inv) = host.get_guest_request() {
        write_bytes_to_memory(ctx, ptr, &inv.msg);
        write_bytes_to_memory(ctx, op_ptr, &inv.operation.as_bytes());
    }
}

pub(crate) fn host_response(ctx: &CallContext, ptr: i32, host: Arc<ModuleState>) {
    if let Some(ref r) = host.get_host_response() {
        write_bytes_to_memory(ctx, ptr, &r);
    }
}

pub(crate) fn host_response_length(_ctx: &CallContext, host: Arc<ModuleState>) -> i32 {
    host.get_host_response().unwrap_or(vec![]).len() as _
}

pub(crate) fn console_log(ctx: &CallContext, ptr: i32, len: i32, host: Arc<ModuleState>) {
    let vec = get_vec_from_memory(ctx, ptr, len);
    let msg = std::str::from_utf8(&vec).unwrap();
    host.do_console_log(msg);
}

// Sets the guest response by telling the host "you can find the response binary here, and it's x bytes"
pub(crate) fn guest_response(ctx: &CallContext, ptr: i32, len: i32, host: Arc<ModuleState>) {
    let vec = get_vec_from_memory(ctx, ptr, len);
    host.set_guest_response(vec);
}

// Sets the guest error by telling the host "you can find the error binary here, and it's x bytes"
pub(crate) fn guest_error(ctx: &CallContext, ptr: i32, len: i32, host: Arc<ModuleState>) {
    let vec = get_vec_from_memory(ctx, ptr, len);
    host.set_guest_error(String::from_utf8(vec).unwrap());
}

// Writes the host error, if any, to the linear memory at the location supplied by the guest
pub(crate) fn host_error(ctx: &CallContext, ptr: i32, host: Arc<ModuleState>) {
    if let Some(ref e) = host.get_host_error() {
        write_bytes_to_memory(ctx, ptr, e.as_bytes());
    }
}

// Returns the length of the host error, 0 if there is none.
pub(crate) fn host_error_length(host: Arc<ModuleState>) -> i32 {
    host.get_host_error().unwrap_or("".to_string()).len() as _
}

fn get_vec_from_memory(ctx: &CallContext, ptr: i32, len: i32) -> Vec<u8> {
    let data = unsafe { &*ctx.memory() };

    data[ptr as usize..][..len as usize].to_vec()
}

fn write_bytes_to_memory(ctx: &CallContext, ptr: i32, slice: &[u8]) {
    unsafe {
        (&mut *ctx.memory_mut())[ptr as usize..][..slice.len()].copy_from_slice(slice);
    };
}