3411795ac7
This adds this interface `wasm.Store` which gives access to functions in a store without leaking an API to change the store. This is primarily to support configuration use cases where post-initialization, there's no need or desire to mutate the store. This also backfills codecs needed to handle float results. Signed-off-by: Adrian Cole <adrian@tetrate.io> Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
66 lines
2.1 KiB
Go
66 lines
2.1 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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mod, err := wazero.DecodeModuleText([]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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store := wazero.NewStore()
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// Host functions can be exported as any module name, including the empty string.
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_, err = wazero.ExportHostFunctions(store, "", map[string]interface{}{"random": goFunc})
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require.NoError(t, err)
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// Configure WASI and implement the function to use it
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we, err := wazero.ExportHostFunctions(store, wasi.ModuleSnapshotPreview1, wazero.WASISnapshotPreview1())
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require.NoError(t, err)
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randomGetFn, ok := we.Function("random_get")
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require.True(t, ok)
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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, mod)
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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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