Golang File.Sync方法代码示例

func main() {
	var tmp *os.File
	var err os.Error

	flag.Parse()
	args := flag.Args()
	if len(args) == 1 {
		dir, _ := path.Split(args[0])
		tmp, err = ioutil.TempFile(dir, "")
		exitOnErr(err)
	} else if len(args) == 2 {
		tmp, err = os.Open(args[1], os.O_RDWR|os.O_CREAT, 0644)
		exitOnErr(err)
	} else {
		usage()
	}

	fname := args[0]
	tmpname := tmp.Name()

	exitOnErr(cdb.Make(tmp, bufio.NewReader(os.Stdin)))
	exitOnErr(tmp.Sync())
	exitOnErr(tmp.Close())
	exitOnErr(os.Rename(tmpname, fname))
}

// CopyFileContents copies the contents of the file named src to the file named
// by dst. The file will be created if it does not already exist. If the
// destination file exists, all it's contents will be replaced by the contents
// of the source file.
//
// From http://stackoverflow.com/a/21067803
func CopyFileContents(src, dst string) (err error) {
	in, err := os.Open(src)
	if err != nil {
		return
	}
	defer in.Close()
	ext := filepath.Ext(dst)
	var out *os.File
	if ext == ".sh" {
		out, err = os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0766)
	} else {
		out, err = os.Create(dst)
	}
	if err != nil {
		return
	}
	defer func() {
		cerr := out.Close()
		if err == nil {
			err = cerr
		}
	}()
	if _, err = io.Copy(out, in); err != nil {
		return
	}
	err = out.Sync()
	return
}

// CopyAs copies a file
func (fh *FileHandle) CopyAs(path string) (err error) {
	var src, dst *os.File

	// open src
	if src, err = os.Open(fh.Path); err != nil {
		return err
	}
	defer src.Close()

	// open dest
	if dst, err = os.Create(path); err != nil {
		return err
	}
	defer func() {
		closeErr := dst.Close()
		if err == nil {
			err = closeErr

			if err == nil {
				// copy success - update file name / path
				fh.Name = filepath.Base(path)
				fh.Path = path
			}
		}
	}()

	// copy
	if _, err = io.Copy(dst, src); err != nil {
		return
	}

	// sync
	err = dst.Sync()
	return
}

// persistMetaData atomically writes state to the filesystem
func (d *DiskQueue) persistMetaData() error {
	var f *os.File
	var err error

	d.metaMutex.Lock()
	depth := d.depth
	readFileNum := d.readFileNum
	readPos := d.readPos
	writeFileNum := d.writeFileNum
	writePos := d.writePos
	d.metaMutex.Unlock()

	fileName := d.metaDataFileName()
	tmpFileName := fileName + ".tmp"

	// write to tmp file
	f, err = os.OpenFile(tmpFileName, os.O_RDWR|os.O_CREATE, 0600)
	if err != nil {
		return err
	}

	_, err = fmt.Fprintf(f, "%d\n%d,%d\n%d,%d\n",
		depth,
		readFileNum, readPos,
		writeFileNum, writePos)
	if err != nil {
		f.Close()
		return err
	}
	f.Sync()
	f.Close()

	// atomically rename
	return os.Rename(tmpFileName, fileName)
}

func CreateFile(name string) (flvFile *File, err error) {
	var file *os.File
	// Create file
	if file, err = os.Create(name); err != nil {
		return
	}
	// Write flv header
	if _, err = file.Write(HEADER_BYTES); err != nil {
		file.Close()
		return
	}

	// Sync to disk
	if err = file.Sync(); err != nil {
		file.Close()
		return
	}

	flvFile = &File{
		file:      file,
		name:      name,
		readOnly:  false,
		headerBuf: make([]byte, 11),
		duration:  0.0,
	}

	return
}

func mapPairToCSV(colHeader string, inMap PairList, fh *os.File, geo *geoip.GeoIP) int {

	nb, err := fh.WriteString(colHeader + "\n")
	check(err)
	totalBytes := nb
	i := 0

	for _, v1 := range inMap {

		matches := regexp.MustCompile(`([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)`).FindStringSubmatch(v1.Key)
		if len(matches) >= 1 && geo != nil {
			record := geo.GetRecord(v1.Key)
			if record != nil {
				nb, err = fh.WriteString(v1.Key + csvd + strconv.Itoa(v1.Value) + csvd + record.City + csvd + record.CountryName + "\n")
			}
		} else {
			nb, err = fh.WriteString(v1.Key + csvd + strconv.Itoa(v1.Value) + "\n")
		}
		check(err)
		totalBytes += nb
		i++
	}
	fh.Sync()
	return totalBytes
}

func (d *Daemon) handle(input link.Input, process *os.Process, stdin *os.File) error {
	if input.WindowSize != nil {
		setWinSize(stdin, input.WindowSize.Columns, input.WindowSize.Rows)
		process.Signal(syscall.SIGWINCH)
	} else if input.EOF {
		stdin.Sync()
		err := stdin.Close()
		if d.WithTty {
			process.Signal(syscall.SIGHUP)
		}
		if err != nil {
			return err
		}
	} else if input.Signal != nil {
		if input.Signal.Signal == garden.SignalTerminate {
			process.Signal(syscall.SIGTERM)
		} else if input.Signal.Signal == garden.SignalKill {
			process.Signal(syscall.SIGKILL)
		}
	} else {
		_, err := stdin.Write(input.StdinData)
		if err != nil {
			return err
		}
	}

	return nil
}

// Loop receiving and processing link requests on the given connection.
// The loop terminates when the connection is closed or an error occurs.
func processLinkRequests(conn net.Conn, stdinW *os.File, cmd *exec.Cmd, withTty bool) {
	decoder := gob.NewDecoder(conn)

	for {
		var input linkpkg.Input
		err := decoder.Decode(&input)
		if err != nil {
			break
		}

		if input.WindowSize != nil {
			setWinSize(stdinW, input.WindowSize.Columns, input.WindowSize.Rows)
			cmd.Process.Signal(syscall.SIGWINCH)
		} else if input.EOF {
			stdinW.Sync()
			err := stdinW.Close()
			if withTty {
				cmd.Process.Signal(syscall.SIGHUP)
			}
			if err != nil {
				conn.Close()
				break
			}
		} else {
			_, err := stdinW.Write(input.Data)
			if err != nil {
				conn.Close()
				break
			}
		}
	}
}

// DumpStacks appends the runtime stack into file in dir and returns full path
// to that file.
func DumpStacks(dir string) (string, error) {
	var (
		buf       []byte
		stackSize int
	)
	bufferLen := 16384
	for stackSize == len(buf) {
		buf = make([]byte, bufferLen)
		stackSize = runtime.Stack(buf, true)
		bufferLen *= 2
	}
	buf = buf[:stackSize]
	var f *os.File
	if dir != "" {
		path := filepath.Join(dir, fmt.Sprintf(stacksLogNameTemplate, strings.Replace(time.Now().Format(time.RFC3339), ":", "", -1)))
		var err error
		f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0666)
		if err != nil {
			return "", errors.Wrap(err, "failed to open file to write the goroutine stacks")
		}
		defer f.Close()
		defer f.Sync()
	} else {
		f = os.Stderr
	}
	if _, err := f.Write(buf); err != nil {
		return "", errors.Wrap(err, "failed to write goroutine stacks")
	}
	return f.Name(), nil
}

// WriteConfigFile wirtes a valid nginx config to f
// Proxies are indicated in routes
// Other configuration specified in config
func WriteConfigFile(f *os.File, routes map[string]int, config Config) {
	var routesBuffer bytes.Buffer
	for path, port := range routes {
		locationStr := "\t\tlocation /%s {\n\t\t\treturn 302 /%s/;\n\t\t}\n\n\t\tlocation /%s/ {\n\t\t\tproxy_pass http://127.0.0.1:%d/;\n\t\t}\n"

		fmt.Fprintf(&routesBuffer, locationStr, path, path, path, port)
	}

	serverName := config.ServerName
	if serverName == "" {
		serverName = "localhost"
	}

	var rootRule string
	defaultPort := config.DefaultPort
	if defaultPort == 0 {
		rootRule = "return 404;"
	} else {
		rootRule = "proxy_pass http://127.0.0.1:" + strconv.Itoa(defaultPort) + ";"
	}

	fmt.Fprintf(f, configText, serverName, routesBuffer.String(), rootRule)

	err := f.Sync()
	if err != nil {
		log.Fatal("Error saving config file: ", err)
	}
}

func readUCHAR8(file *os.File, s int64) ([]byte, int64) {
	buf := make([]byte, s)
	ntotal := int64(0)
	for {
		// read several times because Read might decide to stop intermittently
		buffer := make([]byte, int64(1024)*int64(1024)) // read a little bit
		n, err := file.Read(buffer)
		if ntotal+int64(n) > s {
			n = int(s - ntotal)
		}

		// copy to the real buffer buf
		copy(buf[ntotal:(ntotal+int64(n))], buffer[0:n])
		ntotal = ntotal + int64(n)

		if err == io.EOF {
			break
		}
		if err != nil {
			panic(err)
		}
	}
	file.Sync()
	return buf, ntotal
}

func Write(fn, str string, append bool) error {
	var (
		file *os.File
		err  error
	)
	if append {
		file, err = os.OpenFile(fn, os.O_CREATE|os.O_APPEND|os.O_WRONLY, os.FileMode(0666))
	} else {
		file, err = os.OpenFile(fn, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, os.FileMode(0666))
	}

	defer file.Close()

	if err != nil {
		return err
	}

	_, err = file.WriteString(str)
	if err != nil {
		return err
	}

	file.Sync()
	return nil
}

func Generate_d5sFile(file string, d5sConf *D5ServConf) (e error) {
	var f *os.File
	if file == NULL {
		f = os.Stdout
	} else {
		f, e = os.OpenFile(file, os.O_CREATE|os.O_RDWR|os.O_TRUNC, 0600)
		ThrowErr(e)
		e = f.Truncate(0)
		ThrowErr(e)
		defer func() {
			f.Sync()
			f.Close()
		}()
	}
	if d5sConf == nil {
		d5sConf = new(D5ServConf)
		d5sConf.RSAKeys = GenerateRSAKeyPair()
	}
	desc := getImportableDesc(d5sConf)
	f.WriteString("#\n# deblocus server configuration\n#\n\n")
	for k, d := range desc {
		defaultVal := d.sType.Tag.Get("importable")
		f.WriteString(fmt.Sprintf("%-16s   %s\n", k, defaultVal))
	}
	f.WriteString("\n### Please take good care of this secret file during the server life cycle.\n")
	f.WriteString("### DON'T modify the following lines, unless you known what happens.\n\n")
	k := d5sConf.RSAKeys
	keyBytes := x509.MarshalPKCS1PrivateKey(k.priv)
	keyText := pem.EncodeToMemory(&pem.Block{
		Type:  SER_KEY_TYPE,
		Bytes: keyBytes,
	})
	f.Write(keyText)
	return
}

func ensureSlot(item string) {
	var err error
	var fi *os.File

	slot, err := filepath.Glob(Slots)
	if err != nil {
		panic(err)
	}
	fi, err = os.OpenFile(fmt.Sprintf("%v/slots", slot[0]), os.O_RDWR|os.O_APPEND, 0666)
	if err != nil {
		panic(err)
	}
	defer fi.Close()

	// ensure the slot is not already written into the capemanager
	// (from: https://github.com/mrmorphic/hwio/blob/master/module_bb_pwm.go#L190)
	scanner := bufio.NewScanner(fi)
	for scanner.Scan() {
		line := scanner.Text()
		if strings.Index(line, item) > 0 {
			return
		}
	}

	fi.WriteString(item)
	fi.Sync()

	scanner = bufio.NewScanner(fi)
	for scanner.Scan() {
		line := scanner.Text()
		if strings.Index(line, item) > 0 {
			return
		}
	}
}

// persistMetaData atomically writes state to the filesystem
func (d *diskQueue) persistMetaData() error {
	var f *os.File
	var err error

	fileName := d.metaDataFileName()
	tmpFileName := fmt.Sprintf("%s.%d.tmp", fileName, rand.Int())

	// write to tmp file
	f, err = os.OpenFile(tmpFileName, os.O_RDWR|os.O_CREATE, 0600)
	if err != nil {
		return err
	}

	_, err = fmt.Fprintf(f, "%d\n%d,%d\n%d,%d\n",
		atomic.LoadInt64(&d.depth),
		d.readFileNum, d.readPos,
		d.writeFileNum, d.writePos)
	if err != nil {
		f.Close()
		return err
	}
	f.Sync()
	f.Close()

	// atomically rename
	return atomicRename(tmpFileName, fileName)
}