798ff20f81
This removes WithWorkDirFS and any other attempts to resolve the current directory (".") in host functions. This is a reaction to reality of compilers who track this inside wasm (not via host functions). One nice side effect is substantially simpler internal implementation of file-systems.
This also allows experimental.WithFS to block file access via passing nil.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
61 lines
1.8 KiB
Go
61 lines
1.8 KiB
Go
package main
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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_snapshot_preview1"
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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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defer r.Close(ctx) // This closes everything this Runtime created.
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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.Panicln(err)
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}
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// Combine the above into our baseline config, overriding defaults (which discards stdout and has 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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if _, err = wasi_snapshot_preview1.Instantiate(ctx, r); err != nil {
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log.Panicln(err)
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}
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// Compile the WebAssembly module using the default configuration.
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code, err := r.CompileModule(ctx, catWasm, wazero.NewCompileConfig())
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if err != nil {
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log.Panicln(err)
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}
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// InstantiateModule 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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if _, err = r.InstantiateModule(ctx, code, config.WithArgs("wasi", os.Args[1])); err != nil {
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log.Panicln(err)
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}
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}
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