c4caa1ea9b
Before, we tested the examples/ directory using "ExampleXX", but this is not ideal because it literally embeds the call to `main` into example godoc output. This stops doing that for a different infrastructure. This also makes sure there's a godoc example for both the main package and wasi, so that people looking at https://pkg.go.dev see something and also a link to our real examples directory. Signed-off-by: Adrian Cole <adrian@tetrate.io>
49 lines
1.3 KiB
Go
49 lines
1.3 KiB
Go
package wasi
|
|
|
|
import (
|
|
"fmt"
|
|
"log"
|
|
"os"
|
|
|
|
"github.com/tetratelabs/wazero"
|
|
"github.com/tetratelabs/wazero/sys"
|
|
)
|
|
|
|
// This is an example of how to use WebAssembly System Interface (WASI) with its simplest function: "proc_exit".
|
|
//
|
|
// See https://github.com/tetratelabs/wazero/tree/main/examples/wasi for another example.
|
|
func Example() {
|
|
r := wazero.NewRuntime()
|
|
|
|
// Instantiate WASI, which implements system I/O such as console output.
|
|
wm, err := InstantiateSnapshotPreview1(r)
|
|
if err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
defer wm.Close()
|
|
|
|
// Override default configuration (which discards stdout).
|
|
config := wazero.NewModuleConfig().WithStdout(os.Stdout)
|
|
|
|
// InstantiateModuleFromCodeWithConfig runs the "_start" function which is like a "main" function.
|
|
_, err = r.InstantiateModuleFromCodeWithConfig([]byte(`
|
|
(module
|
|
(import "wasi_snapshot_preview1" "proc_exit" (func $wasi.proc_exit (param $rval i32)))
|
|
|
|
(func $main
|
|
i32.const 2 ;; push $rval onto the stack
|
|
call $wasi.proc_exit ;; return a sys.ExitError to the caller
|
|
)
|
|
(export "_start" (func $main))
|
|
)
|
|
`), config.WithName("wasi-demo"))
|
|
|
|
// Print the exit code
|
|
if exitErr, ok := err.(*sys.ExitError); ok {
|
|
fmt.Printf("exit_code: %d\n", exitErr.ExitCode())
|
|
}
|
|
|
|
// Output:
|
|
// exit_code: 2
|
|
}
|