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193 lines
4.3 KiB
193 lines
4.3 KiB
package common
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import (
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"bufio"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"os/exec"
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"os/signal"
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"path/filepath"
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"strings"
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"syscall"
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)
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var gopath string
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// GoPath returns GOPATH env variable value. If it is not set, this function
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// will try to call `go env GOPATH` subcommand.
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func GoPath() string {
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if gopath != "" {
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return gopath
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}
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path := os.Getenv("GOPATH")
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if len(path) == 0 {
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goCmd := exec.Command("go", "env", "GOPATH")
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out, err := goCmd.Output()
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if err != nil {
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panic(fmt.Sprintf("failed to determine gopath: %v", err))
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}
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path = string(out)
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}
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gopath = path
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return path
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}
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// TrapSignal catches the SIGTERM and executes cb function. After that it exits
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// with code 1.
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func TrapSignal(cb func()) {
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c := make(chan os.Signal, 1)
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signal.Notify(c, os.Interrupt, syscall.SIGTERM)
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go func() {
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for sig := range c {
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fmt.Printf("captured %v, exiting...\n", sig)
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if cb != nil {
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cb()
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}
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os.Exit(1)
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}
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}()
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select {}
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}
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// Kill the running process by sending itself SIGTERM.
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func Kill() error {
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p, err := os.FindProcess(os.Getpid())
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if err != nil {
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return err
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}
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return p.Signal(syscall.SIGTERM)
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}
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func Exit(s string) {
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fmt.Printf(s + "\n")
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os.Exit(1)
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}
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func EnsureDir(dir string, mode os.FileMode) error {
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if _, err := os.Stat(dir); os.IsNotExist(err) {
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err := os.MkdirAll(dir, mode)
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if err != nil {
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return fmt.Errorf("Could not create directory %v. %v", dir, err)
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}
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}
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return nil
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}
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func IsDirEmpty(name string) (bool, error) {
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f, err := os.Open(name)
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if err != nil {
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if os.IsNotExist(err) {
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return true, err
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}
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// Otherwise perhaps a permission
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// error or some other error.
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return false, err
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}
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defer f.Close()
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_, err = f.Readdirnames(1) // Or f.Readdir(1)
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if err == io.EOF {
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return true, nil
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}
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return false, err // Either not empty or error, suits both cases
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}
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func FileExists(filePath string) bool {
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_, err := os.Stat(filePath)
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return !os.IsNotExist(err)
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}
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func ReadFile(filePath string) ([]byte, error) {
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return ioutil.ReadFile(filePath)
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}
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func MustReadFile(filePath string) []byte {
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fileBytes, err := ioutil.ReadFile(filePath)
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if err != nil {
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Exit(Fmt("MustReadFile failed: %v", err))
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return nil
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}
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return fileBytes
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}
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func WriteFile(filePath string, contents []byte, mode os.FileMode) error {
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return ioutil.WriteFile(filePath, contents, mode)
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}
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func MustWriteFile(filePath string, contents []byte, mode os.FileMode) {
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err := WriteFile(filePath, contents, mode)
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if err != nil {
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Exit(Fmt("MustWriteFile failed: %v", err))
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}
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}
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// WriteFileAtomic creates a temporary file with data and the perm given and
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// swaps it atomically with filename if successful.
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func WriteFileAtomic(filename string, data []byte, perm os.FileMode) error {
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var (
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dir = filepath.Dir(filename)
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tempFile = filepath.Join(dir, "write-file-atomic-"+RandStr(32))
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// Override in case it does exist, create in case it doesn't and force kernel
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// flush, which still leaves the potential of lingering disk cache.
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flag = os.O_WRONLY | os.O_CREATE | os.O_SYNC | os.O_TRUNC
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)
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f, err := os.OpenFile(tempFile, flag, perm)
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if err != nil {
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return err
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}
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// Clean up in any case. Defer stacking order is last-in-first-out.
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defer os.Remove(f.Name())
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defer f.Close()
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if n, err := f.Write(data); err != nil {
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return err
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} else if n < len(data) {
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return io.ErrShortWrite
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}
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return os.Rename(f.Name(), filename)
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}
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//--------------------------------------------------------------------------------
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func Tempfile(prefix string) (*os.File, string) {
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file, err := ioutil.TempFile("", prefix)
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if err != nil {
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PanicCrisis(err)
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}
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return file, file.Name()
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}
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func Tempdir(prefix string) (*os.File, string) {
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tempDir := os.TempDir() + "/" + prefix + RandStr(12)
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err := EnsureDir(tempDir, 0700)
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if err != nil {
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panic(Fmt("Error creating temp dir: %v", err))
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}
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dir, err := os.Open(tempDir)
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if err != nil {
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panic(Fmt("Error opening temp dir: %v", err))
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}
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return dir, tempDir
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}
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//--------------------------------------------------------------------------------
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func Prompt(prompt string, defaultValue string) (string, error) {
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fmt.Print(prompt)
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reader := bufio.NewReader(os.Stdin)
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line, err := reader.ReadString('\n')
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if err != nil {
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return defaultValue, err
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} else {
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line = strings.TrimSpace(line)
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if line == "" {
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return defaultValue, nil
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}
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return line, nil
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}
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}
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