examples: implement wasi

Author: Afirium

examples/wasi.zig

@@ -0,0 +1,97 @@
+const std = @import("std");
+const wasmer = @import("wasmer");
+const assert = std.debug.assert;
+
+var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+const allocator = gpa.allocator();
+
+const wat =
+    \\(module
+    \\   (type $mem_size_t (func (result i32)))
+    \\   (type $get_at_t (func (param i32) (result i32)))
+    \\   (type $set_at_t (func (param i32) (param i32)))
+    \\   (memory $mem 1)
+    \\   (func $get_at (type $get_at_t) (param $idx i32) (result i32)
+    \\     (i32.load (local.get $idx)))
+    \\   (func $set_at (type $set_at_t) (param $idx i32) (param $val i32)
+    \\     (i32.store (local.get $idx) (local.get $val)))
+    \\   (func $mem_size (type $mem_size_t) (result i32)
+    \\     (memory.size))
+    \\   (export "get_at" (func $get_at))
+    \\   (export "set_at" (func $set_at))
+    \\   (export "mem_size" (func $mem_size))
+    \\   (export "memory" (memory $mem)))
+;
+
+pub fn main() !void {
+    run() catch |err| {
+        const err_msg = try wasmer.lastError(std.heap.c_allocator);
+        defer std.heap.c_allocator.free(err_msg);
+
+        std.log.err("{s}", .{err_msg});
+
+        return err;
+    };
+}
+
+pub fn run() !void {
+    std.log.info("creating the store...", .{});
+
+    const engine = try wasmer.Engine.init();
+    defer engine.deinit();
+    const store = try wasmer.Store.init(engine);
+    defer store.deinit();
+
+    std.log.info("setting up WASI...", .{});
+
+    const wasi_config = try wasmer.WasiConfig.init();
+
+    const js_string =
+        \\function greet(name) {
+        \\    return JSON.stringify('Hello, ' + name);
+        \\};
+        \\
+        \\print(greet('World'));
+    ;
+
+    wasi_config.setArg("--eval");
+    wasi_config.setArg(js_string);
+
+    std.log.info("loading binary...", .{});
+
+    const file_content = @embedFile("./assets/qjs.wasm");
+
+    var binary = wasmer.ByteVec.fromSlice(file_content);
+    defer binary.deinit();
+
+    std.log.info("compiling module...", .{});
+
+    const module = try wasmer.Module.init(store, binary.toSlice());
+    defer module.deinit();
+
+    const wasi_env = try wasmer.WasiEnv.init(store, wasi_config);
+    defer wasi_env.deinit();
+
+    std.log.info("instantiating module...", .{});
+
+    var imports = try wasmer.getImports(store, wasi_env, module);
+    imports = try wasmer.getImports(store, wasi_env, module);
+    defer imports.deinit();
+
+    const instance = try wasmer.Instance.initFromImports(store, module, &imports);
+    defer instance.deinit();
+
+    try wasi_env.initializeInstance(store, instance);
+
+    std.log.info("extracting exports...", .{});
+
+    const run_func = try wasmer.getStartFunction(instance);
+    defer run_func.deinit();
+
+    std.log.info("calling export...", .{});
+
+    run_func.call(void, .{}) catch |err| {
+        std.log.err("Failed to call \"run_func\": {any}", .{err});
+        return err;
+    };
+}