18 // GoPath returns GOPATH env variable value. If it is not set, this function
19 // will try to call `go env GOPATH` subcommand.
20 func GoPath() string {
25 path := os.Getenv("GOPATH")
27 goCmd := exec.Command("go", "env", "GOPATH")
28 out, err := goCmd.Output()
30 panic(fmt.Sprintf("failed to determine gopath: %v", err))
38 // TrapSignal catches the SIGTERM and executes cb function. After that it exits
40 func TrapSignal(cb func()) {
41 c := make(chan os.Signal, 1)
42 signal.Notify(c, os.Interrupt, os.Kill, syscall.SIGHUP, syscall.SIGINT, syscall.SIGQUIT, syscall.SIGTERM, syscall.SIGKILL)
45 fmt.Printf("captured %v, exiting...\n", sig)
55 // Kill the running process by sending itself SIGTERM.
57 p, err := os.FindProcess(os.Getpid())
61 return p.Signal(syscall.SIGTERM)
69 func EnsureDir(dir string, mode os.FileMode) error {
70 if _, err := os.Stat(dir); os.IsNotExist(err) {
71 err := os.MkdirAll(dir, mode)
73 return fmt.Errorf("Could not create directory %v. %v", dir, err)
79 func IsDirEmpty(name string) (bool, error) {
80 f, err := os.Open(name)
82 if os.IsNotExist(err) {
85 // Otherwise perhaps a permission
86 // error or some other error.
91 _, err = f.Readdirnames(1) // Or f.Readdir(1)
95 return false, err // Either not empty or error, suits both cases
98 func FileExists(filePath string) bool {
99 _, err := os.Stat(filePath)
100 return !os.IsNotExist(err)
103 func ReadFile(filePath string) ([]byte, error) {
104 return ioutil.ReadFile(filePath)
107 func MustReadFile(filePath string) []byte {
108 fileBytes, err := ioutil.ReadFile(filePath)
110 Exit(Fmt("MustReadFile failed: %v", err))
116 func WriteFile(filePath string, contents []byte, mode os.FileMode) error {
117 return ioutil.WriteFile(filePath, contents, mode)
120 func MustWriteFile(filePath string, contents []byte, mode os.FileMode) {
121 err := WriteFile(filePath, contents, mode)
123 Exit(Fmt("MustWriteFile failed: %v", err))
127 // WriteFileAtomic writes newBytes to temp and atomically moves to filePath
128 // when everything else succeeds.
129 func WriteFileAtomic(filePath string, newBytes []byte, mode os.FileMode) error {
130 dir := filepath.Dir(filePath)
131 f, err := ioutil.TempFile(dir, "")
135 _, err = f.Write(newBytes)
139 if closeErr := f.Close(); err == nil {
142 if permErr := os.Chmod(f.Name(), mode); err == nil {
146 err = os.Rename(f.Name(), filePath)
148 // any err should result in full cleanup
155 //--------------------------------------------------------------------------------
157 func Tempfile(prefix string) (*os.File, string) {
158 file, err := ioutil.TempFile("", prefix)
162 return file, file.Name()
165 func Tempdir(prefix string) (*os.File, string) {
166 tempDir := os.TempDir() + "/" + prefix + RandStr(12)
167 err := EnsureDir(tempDir, 0700)
169 panic(Fmt("Error creating temp dir: %v", err))
171 dir, err := os.Open(tempDir)
173 panic(Fmt("Error opening temp dir: %v", err))
178 //--------------------------------------------------------------------------------
180 func Prompt(prompt string, defaultValue string) (string, error) {
182 reader := bufio.NewReader(os.Stdin)
183 line, err := reader.ReadString('\n')
185 return defaultValue, err
187 line = strings.TrimSpace(line)
189 return defaultValue, nil