packer/helper/wrappedstreams/streams_other.go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

//go:build !windows
// +build !windows

package wrappedstreams

import (
	"os"
	"sync"
)

var initOnce sync.Once

func initPlatform() {
	// These must be initialized lazily, once it's been determined that this is
	// a wrapped process.
	initOnce.Do(func() {
		// The standard streams are passed in via extra file descriptors.
		wrappedStdin = os.NewFile(uintptr(3), "stdin")
		wrappedStdout = os.NewFile(uintptr(4), "stdout")
		wrappedStderr = os.NewFile(uintptr(5), "stderr")
	})
}