45ff2fe12f
This prepares for exposing operations like Memory.Grow while keeping the ability to trace what did that, by adding a `context.Context` initial parameter. This adds this to all API methods that mutate or return mutated data. Before, we made a change to trace functions and general lifecycle commands, but we missed this part. Ex. We track functions, but can't track what closed the module, changed memory or a mutable constant. Changing to do this now is not only more consistent, but helps us optimize at least the interpreter to help users identify otherwise opaque code that can cause harm. This is critical before we add more functions that can cause harm, such as Memory.Grow. Signed-off-by: Adrian Cole <adrian@tetrate.io>
59 lines
1.7 KiB
Go
59 lines
1.7 KiB
Go
package wasi_example
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import (
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"context"
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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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// Choose the context to use for function calls.
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ctx := context.Background()
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// Create a new WebAssembly Runtime.
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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(ctx, 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(ctx)
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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(ctx, 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(ctx)
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}
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