0186e41b27
This makes instantiating host or wasm-defined modules similar, by using XXXConfig types. Doing so also allows configuration engines to seed properties. Since decoded modules are only usable during instantiation, this pushes decoding inside those functions. By doing so, the API is easier to use as it has less choices and less errors to catch. Detection is done internally by peeking at the magic number. See https://github.com/tetratelabs/wazero/issues/279 Signed-off-by: Adrian Cole <adrian@tetrate.io>
63 lines
2.0 KiB
Go
63 lines
2.0 KiB
Go
package examples
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import (
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"bytes"
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"fmt"
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"testing"
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"github.com/stretchr/testify/require"
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"github.com/tetratelabs/wazero"
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"github.com/tetratelabs/wazero/wasi"
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"github.com/tetratelabs/wazero/wasm"
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)
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func Test_WASI(t *testing.T) {
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// built-in WASI function to write a random value to memory
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randomGet := func(ctx wasm.ModuleContext, buf, bufLen uint32) wasi.Errno {
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panic("unimplemented")
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}
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stdout := new(bytes.Buffer)
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goFunc := func(ctx wasm.ModuleContext) {
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// Write 8 random bytes to memory using WASI.
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errno := randomGet(ctx, 0, 8)
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require.Equal(t, wasi.ErrnoSuccess, errno)
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// Read them back and print it in hex!
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random, ok := ctx.Memory().ReadUint64Le(0)
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require.True(t, ok)
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_, _ = fmt.Fprintf(stdout, "random: %x\n", random)
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}
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store := wazero.NewStore()
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// Host functions can be exported as any module name, including the empty string.
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env := &wazero.HostModuleConfig{Name: "", Functions: map[string]interface{}{"random": goFunc}}
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_, err := wazero.InstantiateHostModule(store, env)
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// Configure WASI and implement the function to use it
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we, err := wazero.InstantiateHostModule(store, wazero.WASISnapshotPreview1())
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require.NoError(t, err)
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randomGetFn := we.Function("random_get")
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// Implement the function pointer. This mainly shows how you can decouple a host function dependency.
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randomGet = func(ctx wasm.ModuleContext, buf, bufLen uint32) wasi.Errno {
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res, err := randomGetFn(ctx, uint64(buf), uint64(bufLen))
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require.NoError(t, err)
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return wasi.Errno(res[0])
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}
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// The "random" function was imported as $random in Wasm. Since it was marked as the start
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// function, it is invoked on instantiation. Ensure that worked: "random" was called!
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_, err = wazero.InstantiateModule(store, &wazero.ModuleConfig{Source: []byte(`(module $wasi
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(import "wasi_snapshot_preview1" "random_get"
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(func $wasi.random_get (param $buf i32) (param $buf_len i32) (result (;errno;) i32)))
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(import "" "random" (func $random))
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(memory 1)
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(start $random)
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)`)})
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require.NoError(t, err)
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require.Contains(t, stdout.String(), "random: ")
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}
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