system: new file writer for updating env-style files
This can be used to safely update config files cloudinit does not have exclusive control over. For example update.conf or /etc/environment.
This commit is contained in:
Michael Marineau
parent
98c26440be
commit
81824be3bf
86
system/env_file.go
Normal file
86
system/env_file.go
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@ -0,0 +1,86 @@
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package system
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import (
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"bytes"
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"fmt"
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"io/ioutil"
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"os"
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"path"
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"regexp"
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)
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type EnvFile struct {
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Vars map[string]string
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// mask File.Content, it shouldn't be used.
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Content interface{} `json:"-" yaml:"-"`
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*File
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}
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// only allow sh compatible identifiers
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var validKey = regexp.MustCompile(`^[a-zA-Z0-9_]+$`)
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// match each line, optionally capturing valid identifiers, discarding dos line endings
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var lineLexer = regexp.MustCompile(`(?m)^((?:([a-zA-Z0-9_]+)=)?.*?)\r?\n`)
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func updateEnv(old []byte, pending map[string]string) []byte {
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var buf bytes.Buffer
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var match [][]byte
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// it is awkward for the regex to handle a missing newline gracefully
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if len(old) != 0 && !bytes.HasSuffix(old, []byte{'\n'}) {
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old = append(old, byte('\n'))
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}
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for _, match = range lineLexer.FindAllSubmatch(old, -1) {
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key := string(match[2])
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if value, ok := pending[key]; ok {
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fmt.Fprintf(&buf, "%s=%s\n", key, value)
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delete(pending, key)
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} else {
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fmt.Fprintf(&buf, "%s\n", match[1])
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}
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}
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for key, value := range pending {
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fmt.Fprintf(&buf, "%s=%s\n", key, value)
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}
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return buf.Bytes()
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}
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// WriteEnvFile updates an existing env `KEY=value` formated file with
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// new values provided in EnvFile.Vars; File.Content is ignored.
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// Existing ordering and any unknown formatting such as comments are
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// preserved. If no changes are required the file is untouched.
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func WriteEnvFile(ef *EnvFile, root string) error {
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// validate new keys, updateEnv uses pending to track writes
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pending := make(map[string]string, len(ef.Vars))
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for key, value := range ef.Vars {
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if !validKey.MatchString(key) {
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return fmt.Errorf("Invalid name %q for %s", key, ef.Path)
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}
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pending[key] = value
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}
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if len(pending) == 0 {
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return nil
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}
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oldContent, err := ioutil.ReadFile(path.Join(root, ef.Path))
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if err != nil {
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if os.IsNotExist(err) {
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oldContent = []byte{}
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} else {
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return err
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}
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}
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newContent := updateEnv(oldContent, pending)
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if bytes.Equal(oldContent, newContent) {
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return nil
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}
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ef.File.Content = string(newContent)
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_, err = WriteFile(ef.File, root)
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return err
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}
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385
system/env_file_test.go
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385
system/env_file_test.go
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@ -0,0 +1,385 @@
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package system
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import (
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"io/ioutil"
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"os"
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"path"
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"strings"
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"testing"
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)
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const (
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base = "# a file\nFOO=base\n\nBAR= hi there\n"
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baseNoNewline = "# a file\nFOO=base\n\nBAR= hi there"
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baseDos = "# a file\r\nFOO=base\r\n\r\nBAR= hi there\r\n"
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expectUpdate = "# a file\nFOO=test\n\nBAR= hi there\nNEW=a value\n"
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expectCreate = "FOO=test\nNEW=a value\n"
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)
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var (
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valueUpdate = map[string]string{
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"FOO": "test",
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"NEW": "a value",
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}
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valueNoop = map[string]string{
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"FOO": "base",
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}
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valueEmpty = map[string]string{}
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valueInvalid = map[string]string{
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"FOO-X": "test",
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}
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)
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func TestWriteEnvFileUpdate(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(base), 0644)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueUpdate,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != expectUpdate {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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}
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func TestWriteEnvFileUpdateNoNewline(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(baseNoNewline), 0644)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueUpdate,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != expectUpdate {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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}
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func TestWriteEnvFileCreate(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueUpdate,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != expectCreate {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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}
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func TestWriteEnvFileNoop(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(base), 0644)
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oldStat, err := os.Stat(fullPath)
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if err != nil {
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t.Fatal("Unable to stat file: %v", err)
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}
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueNoop,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != base {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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newStat, err := os.Stat(fullPath)
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if err != nil {
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t.Fatal("Unable to stat file: %v", err)
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}
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if oldStat.ModTime() != newStat.ModTime() {
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t.Fatal("File mtime changed.")
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}
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}
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func TestWriteEnvFileUpdateDos(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(baseDos), 0644)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueUpdate,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != expectUpdate {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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}
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// A middle ground noop, values are unchanged but we did have a value.
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// Seems reasonable to rewrite the file in Unix format anyway.
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func TestWriteEnvFileDos2Unix(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(baseDos), 0644)
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oldStat, err := os.Stat(fullPath)
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if err != nil {
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t.Fatal("Unable to stat file: %v", err)
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}
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueNoop,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != base {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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newStat, err := os.Stat(fullPath)
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if err != nil {
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t.Fatal("Unable to stat file: %v", err)
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}
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if oldStat.ModTime() != newStat.ModTime() {
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t.Fatal("File mtime changed.")
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}
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}
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// If it really is a noop (structure is empty) don't even do dos2unix
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func TestWriteEnvFileEmpty(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(baseDos), 0644)
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oldStat, err := os.Stat(fullPath)
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if err != nil {
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t.Fatal("Unable to stat file: %v", err)
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}
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueEmpty,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err != nil {
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t.Fatalf("Unable to read expected file: %v", err)
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}
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if string(contents) != baseDos {
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t.Fatalf("File has incorrect contents: %q", contents)
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}
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newStat, err := os.Stat(fullPath)
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if err != nil {
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t.Fatal("Unable to stat file: %v", err)
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}
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if oldStat.ModTime() != newStat.ModTime() {
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t.Fatal("File mtime changed.")
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}
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}
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// no point in creating empty files
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func TestWriteEnvFileEmptyNoCreate(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueEmpty,
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}
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err = WriteEnvFile(&ef, dir)
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if err != nil {
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t.Fatalf("WriteFile failed: %v", err)
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}
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contents, err := ioutil.ReadFile(fullPath)
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if err == nil {
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t.Fatalf("File has incorrect contents: %q", contents)
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} else if !os.IsNotExist(err) {
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t.Fatalf("Unexpected error while reading file: %v", err)
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}
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}
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func TestWriteEnvFilePermFailure(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(base), 0000)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueUpdate,
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}
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err = WriteEnvFile(&ef, dir)
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if !os.IsPermission(err) {
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t.Fatalf("Not a pemission denied error: %v", err)
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}
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}
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func TestWriteEnvFileNameFailure(t *testing.T) {
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dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
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if err != nil {
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t.Fatalf("Unable to create tempdir: %v", err)
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}
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defer os.RemoveAll(dir)
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name := "foo.conf"
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fullPath := path.Join(dir, name)
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ioutil.WriteFile(fullPath, []byte(base), 0000)
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ef := EnvFile{
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File: &File{
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Path: name,
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},
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Vars: valueInvalid,
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}
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err = WriteEnvFile(&ef, dir)
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if err == nil || !strings.HasPrefix(err.Error(), "Invalid name") {
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t.Fatalf("Not an invalid name error: %v", err)
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}
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}
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