Golang File.Close方法代码示例

// Reading a symlink to a file must fail
func TestReadSymlinkedDirectoryToFile(t *testing.T) {
	var err error
	var file *os.File

	if file, err = os.Create("/tmp/testReadSymlinkToFile"); err != nil {
		t.Fatalf("failed to create file: %s", err)
	}

	file.Close()

	if err = os.Symlink("/tmp/testReadSymlinkToFile", "/tmp/fileLinkTest"); err != nil {
		t.Errorf("failed to create symlink: %s", err)
	}

	var path string
	if path, err = ReadSymlinkedDirectory("/tmp/fileLinkTest"); err == nil {
		t.Fatalf("ReadSymlinkedDirectory on a symlink to a file should've failed")
	}

	if path != "" {
		t.Fatalf("path should've been empty: %s", path)
	}

	if err = os.Remove("/tmp/testReadSymlinkToFile"); err != nil {
		t.Errorf("failed to remove file: %s", err)
	}

	if err = os.Remove("/tmp/fileLinkTest"); err != nil {
		t.Errorf("failed to remove symlink: %s", err)
	}
}

func listenStream(netw, addr string) (l net.Listener, err error) {
	var (
		file *os.File
	)

	fd, err := listen(netw, addr)
	if err != nil {
		return nil, err
	}

	// Set backlog size to the maximum
	if err = syscall.Listen(fd, syscall.SOMAXCONN); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	file = os.NewFile(uintptr(fd), filePrefix+strconv.Itoa(os.Getpid()))
	if l, err = net.FileListener(file); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	if err = file.Close(); err != nil {
		syscall.Close(fd)
		l.Close()
		return nil, err
	}

	return l, err
}

func main() {
	var outFile *os.File
	var err error

	if outFile, err = os.Create("create.png"); err != nil {
		println("Error", err)
		return
	}

	defer outFile.Close()

	rect := image.Rect(0, 0, 100, 100)
	rgba := image.NewRGBA64(rect)

	// #golangとか書きたいけど、とりあえず#だけ
	for i := 0; i < 10; i++ {
		rgba.Set(60, (10 + i), image.Black.At(0, 0))
		rgba.Set(65, (10 + i), image.Black.At(0, 0))
		rgba.Set((58 + i), 13, image.Black.At(0, 0))
		rgba.Set((58 + i), 16, image.Black.At(0, 0))
	}

	outImage := rgba.SubImage(rect)

	if err = png.Encode(outFile, outImage); err != nil {
		println("Error", err)
		return
	}

}

func (v *Volume) load(alsoLoadIndex bool) error {
	var e error
	fileName := path.Join(v.dir, v.Id.String())
	if exists, canRead, canWrite, _ := checkFile(fileName + ".dat"); exists && !canRead {
		return fmt.Errorf("cannot read Volume Data file %s.dat", fileName)
	} else if !exists || canWrite {
		v.dataFile, e = os.OpenFile(fileName+".dat", os.O_RDWR|os.O_CREATE, 0644)
	} else if exists && canRead {
		glog.V(0).Infoln("opening " + fileName + ".dat in READONLY mode")
		v.dataFile, e = os.Open(fileName + ".dat")
		v.readOnly = true
	} else {
		return fmt.Errorf("Unknown state about Volume Data file %s.dat", fileName)
	}
	if e != nil {
		if !os.IsPermission(e) {
			return fmt.Errorf("cannot load Volume Data %s.dat: %s", fileName, e.Error())
		}
	}

	if v.ReplicaType == CopyNil {
		e = v.readSuperBlock()
	} else {
		e = v.maybeWriteSuperBlock()
	}
	if e == nil && alsoLoadIndex {
		var indexFile *os.File
		if v.readOnly {
			glog.V(1).Infoln("open to read file", fileName+".idx")
			if indexFile, e = os.OpenFile(fileName+".idx", os.O_RDONLY, 0644); e != nil {
				return fmt.Errorf("cannot read Volume Data %s.dat: %s", fileName, e.Error())
			}

			if v.ensureConvertIdxToCdb(fileName) {
				v.nm, e = OpenCdbMap(fileName + ".cdb")
				return e
			}
			if indexFile != nil {
				glog.V(0).Infoln("converting %s.idx to %s.cdb", fileName, fileName)
				if e = ConvertIndexToCdb(fileName+".cdb", indexFile); e != nil {
					glog.Errorln("error converting %s.idx to %s.cdb: %s", fileName, fileName, e)
				} else {
					indexFile.Close()
					os.Remove(indexFile.Name())
					indexFile = nil
				}
			}
		} else {
			glog.V(1).Infoln("open to write file", fileName+".idx")
			if indexFile, e = os.OpenFile(fileName+".idx", os.O_RDWR|os.O_CREATE, 0644); e != nil {
				return fmt.Errorf("cannot write Volume Data %s.dat: %s", fileName, e.Error())
			}
		}
		glog.V(0).Infoln("loading file", fileName+".idx", "readonly", v.readOnly)
		if v.nm, e = LoadNeedleMap(indexFile); e != nil {
			glog.V(0).Infoln("loading error:", e)
		}
	}
	return e
}

func (v *Volume) ensureConvertIdxToCdb(fileName string) (cdbCanRead bool) {
	var indexFile *os.File
	var e error
	_, cdbCanRead, cdbCanWrite, cdbModTime := checkFile(fileName + ".cdb")
	_, idxCanRead, _, idxModeTime := checkFile(fileName + ".idx")
	if cdbCanRead && cdbModTime.After(idxModeTime) {
		return true
	}
	if !cdbCanWrite {
		return false
	}
	if !idxCanRead {
		glog.V(0).Infoln("Can not read file", fileName+".idx!")
		return false
	}
	glog.V(2).Infoln("opening file", fileName+".idx")
	if indexFile, e = os.Open(fileName + ".idx"); e != nil {
		glog.V(0).Infoln("Failed to read file", fileName+".idx !")
		return false
	}
	defer indexFile.Close()
	glog.V(0).Infof("converting %s.idx to %s.cdb", fileName, fileName)
	if e = ConvertIndexToCdb(fileName+".cdb", indexFile); e != nil {
		glog.V(0).Infof("error converting %s.idx to %s.cdb: %s", fileName, fileName, e.Error())
		return false
	}
	return true
}

func main() {
	var file *os.File
	var outFile *os.File
	var img image.Image
	var err error

	if file, err = os.Open("pkg.png"); err != nil {
		println("Error", err)
		return
	}
	defer file.Close()

	if img, err = png.Decode(file); err != nil {
		println("Error", err)
		return
	}

	if outFile, err = os.Create("out_pkg.jpeg"); err != nil {
		println("Error", err)
		return
	}

	option := &jpeg.Options{Quality: 100}
	if err = jpeg.Encode(outFile, img, option); err != nil {
		println()
		return
	}
	defer outFile.Close()
}

func main() {
	var file *os.File
	var err error

	if file, err = os.Open("files/sample.tar.bz2"); err != nil {
		log.Fatalln(err)
	}
	defer file.Close()

	reader := tar.NewReader(bzip2.NewReader(file))

	var header *tar.Header
	for {
		header, err = reader.Next()
		if err == io.EOF {
			// ファイルの最後
			break
		}
		if err != nil {
			log.Fatalln(err)
		}

		buf := new(bytes.Buffer)
		if _, err = io.Copy(buf, reader); err != nil {
			log.Fatalln(err)
		}

		if err = ioutil.WriteFile("output/"+header.Name, buf.Bytes(), 0755); err != nil {
			log.Fatal(err)
		}
	}
}

func readLines(path string) (lines []string, err error) {
	var (
		file   *os.File
		part   []byte
		prefix bool
	)
	if file, err = os.Open(path); err != nil {
		return
	}
	defer file.Close()

	reader := bufio.NewReader(file)
	buffer := bytes.NewBuffer(make([]byte, 0))
	for {
		if part, prefix, err = reader.ReadLine(); err != nil {
			break
		}
		buffer.Write(part)
		if !prefix {
			lines = append(lines, buffer.String())
			buffer.Reset()
		}
	}
	if err == io.EOF {
		err = nil
	}
	return
}

func (f *File) Save() (err error) {
	var done sync.Mutex
	done.Lock()
	f.cbs <- func() {
		defer done.Unlock()
		tmpPath := f.path + "." + strconv.FormatInt(rand.Int63(), 10)
		var tmpF *os.File
		tmpF, err = os.Create(tmpPath)
		if err != nil {
			return
		}
		defer tmpF.Close()
		buf := new(bytes.Buffer)
		err = json.NewEncoder(buf).Encode(f.Obj)
		if err != nil {
			return
		}
		// indent
		indentBuf := new(bytes.Buffer)
		err = json.Indent(indentBuf, buf.Bytes(), "", "    ")
		if err != nil {
			return
		}
		_, err = tmpF.Write(indentBuf.Bytes())
		if err != nil {
			return
		}
		err = os.Rename(tmpPath, f.path)
		if err != nil {
			return
		}
	}
	done.Lock()
	return
}

// Lock creates a lockfile which prevents to open more than one instance
// of the same node (on the same machine).
func (ctx *Context) Lock() (err error) {
	var f *os.File
	var p *os.Process
	var pid int

	lockFile := path.Join(ctx.storageDir, ctx.nodeName+".lock")
	if f, err = os.Open(lockFile); err != nil {
		goto lock
	}
	if _, err = fmt.Fscanf(f, "%d", &pid); err != nil && pid == 0 {
		goto lock
	}
	if p, err = os.FindProcess(pid); err == nil && p != nil {
		if err = p.Signal(os.UnixSignal(0)); err == nil {
			return errors.New(
				fmt.Sprintf("node '%s' is already running",
					ctx.NodeName()))
		}
	}
lock:
	// Write a lock file.
	if f, err = os.Create(lockFile); err == nil {
		pid := os.Getppid()
		f.Write([]byte(fmt.Sprintf("%d", pid)))
		f.Close()
	}
	return nil
}

// Open the file, write to the file, close the file.
// Whichever user is running the function needs write permissions to the file or directory if the file does not yet exist.
func (hook *lfsHook) Fire(entry *logrus.Entry) error {
	var (
		fd   *os.File
		path string
		msg  string
		err  error
		ok   bool
	)
	if path, ok = hook.paths[entry.Level]; !ok {
		err = fmt.Errorf("no file provided for loglevel: %d", entry.Level)
		log.Println(err.Error())
		return err
	}
	fd, err = os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0666)
	if err != nil {
		log.Println("failed to open logfile:", path, err)
		return err
	}
	defer fd.Close()
	msg, err = entry.String()
	if err != nil {
		log.Println("failed to generate string for entry:", err)
		return err
	}
	fd.WriteString(msg)
	return nil
}

// 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)
}

// retrieveMetaData initializes state from the filesystem
func (d *diskQueue) retrieveMetaData() error {
	var f *os.File
	var err error

	fileName := d.metaDataFileName()
	f, err = os.OpenFile(fileName, os.O_RDONLY, 0600)
	if err != nil {
		return err
	}
	defer f.Close()

	var depth int64
	_, err = fmt.Fscanf(f, "%d\n%d,%d\n%d,%d\n",
		&depth,
		&d.readFileNum, &d.readPos,
		&d.writeFileNum, &d.writePos)
	if err != nil {
		return err
	}
	atomic.StoreInt64(&d.depth, depth)
	d.nextReadFileNum = d.readFileNum
	d.nextReadPos = d.readPos

	return nil
}

func export(file string, connection string) {
	var wadokufile *os.File
	var xmldata []byte
	var err error

	if wadokufile, err = os.Open(file); err != nil {
		log.Fatal("Can't open wadoku XML file: " + err.Error())
	}
	defer wadokufile.Close()

	if xmldata, err = ioutil.ReadAll(wadokufile); err != nil {
		log.Fatal("Can't read wadoku XML file: " + err.Error())
	}

	dict := XMLDict{}

	if err = xml.Unmarshal([]byte(xmldata), &dict); err != nil {
		log.Fatal("Can't unmarshal xmldata: " + err.Error())
		return
	}

	if err = saveIntoMongo(dict, connection); err != nil {
		log.Fatal("Can't save entries into mongodb: " + err.Error())
	}
}

func downloadFile(URL string) (fileName string, err error) {
	var file *os.File
	if file, err = ioutil.TempFile(os.TempDir(), "torrent-imageviewer"); err != nil {
		return
	}

	defer func() {
		if err := file.Close(); err != nil {
			log.Printf("Error closing torrent file: %s", err)
		}
	}()

	response, err := http.Get(URL)
	if err != nil {
		return
	}

	defer func() {
		if err := response.Body.Close(); err != nil {
			log.Printf("Error closing torrent file: %s", err)
		}
	}()

	_, err = io.Copy(file, response.Body)

	return file.Name(), err
}