106f96b066
This shows how to define, export and import functions written in Go. Fixes #464 Signed-off-by: Adrian Cole <adrian@tetrate.io> Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>
54 lines
1.5 KiB
Go
54 lines
1.5 KiB
Go
package wasi_example
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import (
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"embed"
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_ "embed"
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"io/fs"
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"log"
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"os"
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"github.com/tetratelabs/wazero"
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"github.com/tetratelabs/wazero/wasi"
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)
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// catFS is an embedded filesystem limited to test.txt
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//go:embed testdata/test.txt
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var catFS embed.FS
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// catWasm was compiled the TinyGo source testdata/cat.go
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//go:embed testdata/cat.wasm
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var catWasm []byte
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// main writes an input file to stdout, just like `cat`.
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//
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// This is a basic introduction to the WebAssembly System Interface (WASI).
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// See https://github.com/WebAssembly/WASI
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func main() {
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r := wazero.NewRuntime()
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// Since wazero uses fs.FS, we can use standard libraries to do things like trim the leading path.
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rooted, err := fs.Sub(catFS, "testdata")
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if err != nil {
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log.Fatal(err)
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}
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// Combine the above into our baseline config, overriding defaults (which discard stdout and have no file system).
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config := wazero.NewModuleConfig().WithStdout(os.Stdout).WithFS(rooted)
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// Instantiate WASI, which implements system I/O such as console output.
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wm, err := wasi.InstantiateSnapshotPreview1(r)
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if err != nil {
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log.Fatal(err)
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}
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defer wm.Close()
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// InstantiateModuleFromCodeWithConfig runs the "_start" function which is what TinyGo compiles "main" to.
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// * Set the program name (arg[0]) to "wasi" and add args to write "test.txt" to stdout twice.
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// * We use "/test.txt" or "./test.txt" because WithFS by default maps the workdir "." to "/".
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cat, err := r.InstantiateModuleFromCodeWithConfig(catWasm, config.WithArgs("wasi", os.Args[1]))
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if err != nil {
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log.Fatal(err)
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}
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defer cat.Close()
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}
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