Switch uses of os.Getenv that check for empty string to os.LookupEnv.

Whether the variable was found is already returned by syscall.Getenv.
os.Getenv drops this value while os.Lookupenv passes it along.

PiperOrigin-RevId: 351674032

pkg/tcpip/link/sharedmem/sharedmem_test.go

@@ -191,8 +191,8 @@ func shuffle(b []int) {
 }
 
 func createFile(t *testing.T, size int64, initQueue bool) int {
-	tmpDir := os.Getenv("TEST_TMPDIR")
-	if tmpDir == "" {
+	tmpDir, ok := os.LookupEnv("TEST_TMPDIR")
+	if !ok {
 		tmpDir = os.Getenv("TMPDIR")
 	}
 	f, err := ioutil.TempFile(tmpDir, "sharedmem_test")

pkg/test/testutil/testutil.go

@@ -83,11 +83,10 @@ func ConfigureExePath() error {
 // TmpDir returns the absolute path to a writable directory that can be used as
 // scratch by the test.
 func TmpDir() string {
-	dir := os.Getenv("TEST_TMPDIR")
-	if dir == "" {
-		dir = "/tmp"
+	if dir, ok := os.LookupEnv("TEST_TMPDIR"); ok {
+		return dir
 	}
-	return dir
+	return "/tmp"
 }
 
 // Logger is a simple logging wrapper.
@@ -543,7 +542,7 @@ func IsStatic(filename string) (bool, error) {
 //
 // See https://docs.bazel.build/versions/master/test-encyclopedia.html#role-of-the-test-runner.
 func TouchShardStatusFile() error {
-	if statusFile := os.Getenv("TEST_SHARD_STATUS_FILE"); statusFile != "" {
+	if statusFile, ok := os.LookupEnv("TEST_SHARD_STATUS_FILE"); ok {
 		cmd := exec.Command("touch", statusFile)
 		if b, err := cmd.CombinedOutput(); err != nil {
 			return fmt.Errorf("touch %q failed:\n output: %s\n error: %s", statusFile, string(b), err.Error())
@@ -565,8 +564,9 @@ func TestIndicesForShard(numTests int) ([]int, error) {
 		shardTotal = 1
 	)
 
-	indexStr, totalStr := os.Getenv("TEST_SHARD_INDEX"), os.Getenv("TEST_TOTAL_SHARDS")
-	if indexStr != "" && totalStr != "" {
+	indexStr, indexOk := os.LookupEnv("TEST_SHARD_INDEX")
+	totalStr, totalOk := os.LookupEnv("TEST_TOTAL_SHARDS")
+	if indexOk && totalOk {
 		// Parse index and total to ints.
 		var err error
 		shardIndex, err = strconv.Atoi(indexStr)

runsc/cmd/gofer_test.go

@@ -24,11 +24,10 @@ import (
 )
 
 func tmpDir() string {
-	dir := os.Getenv("TEST_TMPDIR")
-	if dir == "" {
-		dir = "/tmp"
+	if dir, ok := os.LookupEnv("TEST_TMPDIR"); ok {
+		return dir
 	}
-	return dir
+	return "/tmp"
 }
 
 type dir struct {

runsc/config/flags.go

@@ -114,7 +114,7 @@ func NewFromFlags() (*Config, error) {
 	if len(conf.RootDir) == 0 {
 		// If not set, set default root dir to something (hopefully) user-writeable.
 		conf.RootDir = "/var/run/runsc"
-		if runtimeDir := os.Getenv("XDG_RUNTIME_DIR"); runtimeDir != "" {
+		if runtimeDir, ok := os.LookupEnv("XDG_RUNTIME_DIR"); ok {
 			conf.RootDir = filepath.Join(runtimeDir, "runsc")
 		}
 	}

test/root/crictl_test.go

@@ -353,8 +353,8 @@ func setup(t *testing.T) (*criutil.Crictl, func(), error) {
 	// because the shims will be installed there, and containerd may infer
 	// the binary name and search the PATH.
 	runtimeDir := path.Dir(runtime)
-	modifiedPath := os.Getenv("PATH")
-	if modifiedPath != "" {
+	modifiedPath, ok := os.LookupEnv("PATH")
+	if ok {
 		modifiedPath = ":" + modifiedPath // We prepend below.
 	}
 	modifiedPath = path.Dir(getContainerd()) + modifiedPath

website/cmd/server/main.go

@@ -366,7 +366,7 @@ func registerProfile(mux *http.ServeMux) {
 }
 
 func envFlagString(name, def string) string {
-	if val := os.Getenv(name); val != "" {
+	if val, ok := os.LookupEnv(name); ok {
 		return val
 	}
 	return def