Each script runs in a fresh temporary work directory tree, available to scripts as $WORK.
Scripts also have access to other environment variables, including:

	GOARCH=<target GOARCH>
	GOCACHE=<actual GOCACHE being used outside the test>
	GOEXE=<executable file suffix: .exe on Windows, empty on other systems>
	GOOS=<target GOOS>
	GOPATH=$WORK/gopath
	GOPROXY=<local module proxy serving from cmd/go/testdata/mod>

		`; export GOROOT="` + deviceGoroot + `"` +
		`; export GOPATH="` + deviceGopath + `"` +
		`; export CGO_ENABLED=0` +
		`; export GOPROXY=` + os.Getenv("GOPROXY") +
		`; export GOCACHE="` + deviceRoot + `/gocache"` +
		`; export PATH="` + deviceGoroot + `/bin":$PATH` +
		`; export HOME="` + deviceRoot + `/home"` +
		`; cd "` + deviceCwd + `"` +
		"; '" + deviceBin + "' " + strings.Join(os.Args[2:], " ")

				env[i].Changed = true
			}
		case "GOBIN", "GOEXPERIMENT", "GOFLAGS", "GOINSECURE", "GOPRIVATE", "GOTMPDIR", "GOVCS":
			if env[i].Value != "" {
				env[i].Changed = true
			}
		case "GOCACHE":
			env[i].Value, env[i].Changed = cache.DefaultDir()
		case "GOTOOLCHAIN":
			env[i].Value, env[i].Changed = cfg.EnvOrAndChanged("GOTOOLCHAIN", "")
		case "GODEBUG":
			env[i].Changed = env[i].Value != ""
		}
	}

func runLLDB(target, appdir, deviceapp string, args []string) ([]byte, error) {
	var env []string
	for _, e := range os.Environ() {
		// Don't override TMPDIR, HOME, GOCACHE on the device.
		if strings.HasPrefix(e, "TMPDIR=") || strings.HasPrefix(e, "HOME=") || strings.HasPrefix(e, "GOCACHE=") {
			continue
		}
		env = append(env, e)
	}
	lldb := exec.Command(
		"python",
		"-", // Read script from stdin.
		target,
		appdir,

[!fuzz] skip
[short] skip
env GOCACHE=$WORK/cache

# Test that running a fuzz target that returns without failing or calling
# f.Fuzz fails and causes a non-zero exit status.
! go test noop_fuzz_test.go
! stdout ^ok
stdout FAIL

# Test that fuzzing a fuzz target that returns without failing or calling
# f.Fuzz fails and causes a non-zero exit status.
! go test -fuzz=Fuzz -fuzztime=1x noop_fuzz_test.go
! stdout ^ok
stdout FAIL

	env := []string{
		pathEnvName() + "=" + testBin + string(filepath.ListSeparator) + os.Getenv(pathEnvName()),
		homeEnvName() + "=/no-home",
		"CCACHE_DISABLE=1", // ccache breaks with non-existent HOME
		"GOARCH=" + runtime.GOARCH,
		"TESTGO_GOHOSTARCH=" + goHostArch,
		"GOCACHE=" + testGOCACHE,
		"GOCOVERDIR=" + os.Getenv("GOCOVERDIR"),
		"GODEBUG=" + os.Getenv("GODEBUG"),
		"GOEXE=" + cfg.ExeSuffix,

	can map[ProgCmd]bool

	// fuzzDirCache is another Cache implementation to use for the FuzzDir
	// method. In practice this is the default GOCACHE disk-based
	// implementation.
	//
	// TODO(bradfitz): maybe this isn't ideal. But we'd need to extend the Cache
	// interface and the fuzzing callers to be less disk-y to do more here.
	fuzzDirCache Cache

	closing      atomic.Bool

var HelpCache = &base.Command{
	UsageLine: "cache",
	Short:     "build and test caching",
	Long: `
The go command caches build outputs for reuse in future builds.
The default location for cache data is a subdirectory named go-build
in the standard user cache directory for the current operating system.
Setting the GOCACHE environment variable overrides this default,
and running 'go env GOCACHE' prints the current cache directory.

  # If these are not set, set them now.  This ensures that any subsequent
  # scripts we run (which may call this function again) use the same values.
  export GOCACHE="${GOCACHE:-"${KUBE_GOPATH}/cache/build"}"
  export GOMODCACHE="${GOMODCACHE:-"${KUBE_GOPATH}/cache/mod"}"

  # Make sure our own Go binaries are in PATH.
  export PATH="${KUBE_GOPATH}/bin:${PATH}"

  # Unset GOBIN in case it already exists in the current session.

}

func (c *coordinator) elapsed() time.Duration {
	return time.Since(c.startTime).Round(1 * time.Second)
}

// readCache creates a combined corpus from seed values and values in the cache
// (in GOCACHE/fuzz).
//
// TODO(fuzzing): need a mechanism that can remove values that
// aren't useful anymore, for example, because they have the wrong type.
func (c *coordinator) readCache() error {