vendor/github.com/vmware/govmomi/object/datastore_file.go - cloudstack-kubernetes-provider - Git at Google

 /*
 Copyright (c) 2016-2017 VMware, Inc. All Rights Reserved.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

 package object

 import (
 	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"os"
 	"path"
 	"sync"
 	"time"

 	"github.com/vmware/govmomi/vim25/soap"
 )

 // DatastoreFile implements io.Reader, io.Seeker and io.Closer interfaces for datastore file access.
 type DatastoreFile struct {
 	d    Datastore
 	ctx  context.Context
 	name string

 	buf    io.Reader
 	body   io.ReadCloser
 	length int64
 	offset struct {
 		read, seek int64
 	}
 }

 // Open opens the named file relative to the Datastore.
 func (d Datastore) Open(ctx context.Context, name string) (*DatastoreFile, error) {
 	return &DatastoreFile{
 		d:      d,
 		name:   name,
 		length: -1,
 		ctx:    ctx,
 	}, nil
 }

 // Read reads up to len(b) bytes from the DatastoreFile.
 func (f *DatastoreFile) Read(b []byte) (int, error) {
 	if f.offset.read != f.offset.seek {
 		// A Seek() call changed the offset, we need to issue a new GET
 		_ = f.Close()

 		f.offset.read = f.offset.seek
 	} else if f.buf != nil {
 		// f.buf + f behaves like an io.MultiReader
 		n, err := f.buf.Read(b)
 		if err == io.EOF {
 			f.buf = nil // buffer has been drained
 		}
 		if n > 0 {
 			return n, nil
 		}
 	}

 	body, err := f.get()
 	if err != nil {
 		return 0, err
 	}

 	n, err := body.Read(b)

 	f.offset.read += int64(n)
 	f.offset.seek += int64(n)

 	return n, err
 }

 // Close closes the DatastoreFile.
 func (f *DatastoreFile) Close() error {
 	var err error

 	if f.body != nil {
 		err = f.body.Close()
 		f.body = nil
 	}

 	f.buf = nil

 	return err
 }

 // Seek sets the offset for the next Read on the DatastoreFile.
 func (f *DatastoreFile) Seek(offset int64, whence int) (int64, error) {
 	switch whence {
 	case io.SeekStart:
 	case io.SeekCurrent:
 		offset += f.offset.seek
 	case io.SeekEnd:
 		if f.length < 0 {
 			_, err := f.Stat()
 			if err != nil {
 				return 0, err
 			}
 		}
 		offset += f.length
 	default:
 		return 0, errors.New("Seek: invalid whence")
 	}

 	// allow negative SeekStart for initial Range request
 	if offset < 0 {
 		return 0, errors.New("Seek: invalid offset")
 	}

 	f.offset.seek = offset

 	return offset, nil
 }

 type fileStat struct {
 	file   *DatastoreFile
 	header http.Header
 }

 func (s *fileStat) Name() string {
 	return path.Base(s.file.name)
 }

 func (s *fileStat) Size() int64 {
 	return s.file.length
 }

 func (s *fileStat) Mode() os.FileMode {
 	return 0
 }

 func (s *fileStat) ModTime() time.Time {
 	return time.Now() // no Last-Modified
 }

 func (s *fileStat) IsDir() bool {
 	return false
 }

 func (s *fileStat) Sys() interface{} {
 	return s.header
 }

 func statusError(res *http.Response) error {
 	if res.StatusCode == http.StatusNotFound {
 		return os.ErrNotExist
 	}
 	return errors.New(res.Status)
 }

 // Stat returns the os.FileInfo interface describing file.
 func (f *DatastoreFile) Stat() (os.FileInfo, error) {
 	// TODO: consider using Datastore.Stat() instead
 	u, p, err := f.d.downloadTicket(f.ctx, f.name, &soap.Download{Method: "HEAD"})
 	if err != nil {
 		return nil, err
 	}

 	res, err := f.d.Client().DownloadRequest(f.ctx, u, p)
 	if err != nil {
 		return nil, err
 	}

 	if res.StatusCode != http.StatusOK {
 		return nil, statusError(res)
 	}

 	f.length = res.ContentLength

 	return &fileStat{f, res.Header}, nil
 }

 func (f *DatastoreFile) get() (io.Reader, error) {
 	if f.body != nil {
 		return f.body, nil
 	}

 	u, p, err := f.d.downloadTicket(f.ctx, f.name, nil)
 	if err != nil {
 		return nil, err
 	}

 	if f.offset.read != 0 {
 		p.Headers = map[string]string{
 			"Range": fmt.Sprintf("bytes=%d-", f.offset.read),
 		}
 	}

 	res, err := f.d.Client().DownloadRequest(f.ctx, u, p)
 	if err != nil {
 		return nil, err
 	}

 	switch res.StatusCode {
 	case http.StatusOK:
 		f.length = res.ContentLength
 	case http.StatusPartialContent:
 		var start, end int
 		cr := res.Header.Get("Content-Range")
 		_, err = fmt.Sscanf(cr, "bytes %d-%d/%d", &start, &end, &f.length)
 		if err != nil {
 			f.length = -1
 		}
 	case http.StatusRequestedRangeNotSatisfiable:
 		// ok: Read() will return io.EOF
 	default:
 		return nil, statusError(res)
 	}

 	if f.length < 0 {
 		_ = res.Body.Close()
 		return nil, errors.New("unable to determine file size")
 	}

 	f.body = res.Body

 	return f.body, nil
 }

 func lastIndexLines(s []byte, line *int, include func(l int, m string) bool) (int64, bool) {
 	i := len(s) - 1
 	done := false

 	for i > 0 {
 		o := bytes.LastIndexByte(s[:i], '\n')
 		if o < 0 {
 			break
 		}

 		msg := string(s[o+1 : i+1])
 		if !include(*line, msg) {
 			done = true
 			break
 		} else {
 			i = o
 			*line++
 		}
 	}

 	return int64(i), done
 }

 // Tail seeks to the position of the last N lines of the file.
 func (f *DatastoreFile) Tail(n int) error {
 	return f.TailFunc(n, func(line int, _ string) bool { return n > line })
 }

 // TailFunc will seek backwards in the datastore file until it hits a line that does
 // not satisfy the supplied `include` function.
 func (f *DatastoreFile) TailFunc(lines int, include func(line int, message string) bool) error {
 	// Read the file in reverse using bsize chunks
 	const bsize = int64(1024 * 16)

 	fsize, err := f.Seek(0, io.SeekEnd)
 	if err != nil {
 		return err
 	}

 	if lines == 0 {
 		return nil
 	}

 	chunk := int64(-1)

 	buf := bytes.NewBuffer(make([]byte, 0, bsize))
 	line := 0

 	for {
 		var eof bool
 		var pos int64

 		nread := bsize

 		offset := chunk * bsize
 		remain := fsize + offset

 		if remain < 0 {
 			if pos, err = f.Seek(0, io.SeekStart); err != nil {
 				return err
 			}

 			nread = bsize + remain
 			eof = true
 		} else {
 			if pos, err = f.Seek(offset, io.SeekEnd); err != nil {
 				return err
 			}
 		}

 		if _, err = io.CopyN(buf, f, nread); err != nil {
 			if err != io.EOF {
 				return err
 			}
 		}

 		b := buf.Bytes()
 		idx, done := lastIndexLines(b, &line, include)

 		if done {
 			if chunk == -1 {
 				// We found all N lines in the last chunk of the file.
 				// The seek offset is also now at the current end of file.
 				// Save this buffer to avoid another GET request when Read() is called.
 				buf.Next(int(idx + 1))
 				f.buf = buf
 				return nil
 			}

 			if _, err = f.Seek(pos+idx+1, io.SeekStart); err != nil {
 				return err
 			}

 			break
 		}

 		if eof {
 			if remain < 0 {
 				// We found < N lines in the entire file, so seek to the start.
 				_, _ = f.Seek(0, io.SeekStart)
 			}
 			break
 		}

 		chunk--
 		buf.Reset()
 	}

 	return nil
 }

 type followDatastoreFile struct {
 	r *DatastoreFile
 	c chan struct{}
 	i time.Duration
 	o sync.Once
 }

 // Read reads up to len(b) bytes from the DatastoreFile being followed.
 // This method will block until data is read, an error other than io.EOF is returned or Close() is called.
 func (f *followDatastoreFile) Read(p []byte) (int, error) {
 	offset := f.r.offset.seek
 	stop := false

 	for {
 		n, err := f.r.Read(p)
 		if err != nil && err == io.EOF {
 			_ = f.r.Close() // GET request body has been drained.
 			if stop {
 				return n, err
 			}
 			err = nil
 		}

 		if n > 0 {
 			return n, err
 		}

 		select {
 		case <-f.c:
 			// Wake up and stop polling once the body has been drained
 			stop = true
 		case <-time.After(f.i):
 		}

 		info, serr := f.r.Stat()
 		if serr != nil {
 			// Return EOF rather than 404 if the file goes away
 			if serr == os.ErrNotExist {
 				_ = f.r.Close()
 				return 0, io.EOF
 			}
 			return 0, serr
 		}

 		if info.Size() < offset {
 			// assume file has be truncated
 			offset, err = f.r.Seek(0, io.SeekStart)
 			if err != nil {
 				return 0, err
 			}
 		}
 	}
 }

 // Close will stop Follow polling and close the underlying DatastoreFile.
 func (f *followDatastoreFile) Close() error {
 	f.o.Do(func() { close(f.c) })
 	return nil
 }

 // Follow returns an io.ReadCloser to stream the file contents as data is appended.
 func (f *DatastoreFile) Follow(interval time.Duration) io.ReadCloser {
 	return &followDatastoreFile{
 		r: f,
 		c: make(chan struct{}),
 		i: interval,
 	}
 }
	/*
	Copyright (c) 2016-2017 VMware, Inc. All Rights Reserved.

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	*/

	package object

	import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"path"
	"sync"
	"time"

	"github.com/vmware/govmomi/vim25/soap"
	)

	// DatastoreFile implements io.Reader, io.Seeker and io.Closer interfaces for datastore file access.
	type DatastoreFile struct {
	d Datastore
	ctx context.Context
	name string

	buf io.Reader
	body io.ReadCloser
	length int64
	offset struct {
	read, seek int64
	}
	}

	// Open opens the named file relative to the Datastore.
	func (d Datastore) Open(ctx context.Context, name string) (*DatastoreFile, error) {
	return &DatastoreFile{
	d: d,
	name: name,
	length: -1,
	ctx: ctx,
	}, nil
	}

	// Read reads up to len(b) bytes from the DatastoreFile.
	func (f *DatastoreFile) Read(b []byte) (int, error) {
	if f.offset.read != f.offset.seek {
	// A Seek() call changed the offset, we need to issue a new GET
	_ = f.Close()

	f.offset.read = f.offset.seek
	} else if f.buf != nil {
	// f.buf + f behaves like an io.MultiReader
	n, err := f.buf.Read(b)
	if err == io.EOF {
	f.buf = nil // buffer has been drained
	}
	if n > 0 {
	return n, nil
	}
	}

	body, err := f.get()
	if err != nil {
	return 0, err
	}

	n, err := body.Read(b)

	f.offset.read += int64(n)
	f.offset.seek += int64(n)

	return n, err
	}

	// Close closes the DatastoreFile.
	func (f *DatastoreFile) Close() error {
	var err error

	if f.body != nil {
	err = f.body.Close()
	f.body = nil
	}

	f.buf = nil

	return err
	}

	// Seek sets the offset for the next Read on the DatastoreFile.
	func (f *DatastoreFile) Seek(offset int64, whence int) (int64, error) {
	switch whence {
	case io.SeekStart:
	case io.SeekCurrent:
	offset += f.offset.seek
	case io.SeekEnd:
	if f.length < 0 {
	_, err := f.Stat()
	if err != nil {
	return 0, err
	}
	}
	offset += f.length
	default:
	return 0, errors.New("Seek: invalid whence")
	}

	// allow negative SeekStart for initial Range request
	if offset < 0 {
	return 0, errors.New("Seek: invalid offset")
	}

	f.offset.seek = offset

	return offset, nil
	}

	type fileStat struct {
	file *DatastoreFile
	header http.Header
	}

	func (s *fileStat) Name() string {
	return path.Base(s.file.name)
	}

	func (s *fileStat) Size() int64 {
	return s.file.length
	}

	func (s *fileStat) Mode() os.FileMode {
	return 0
	}

	func (s *fileStat) ModTime() time.Time {
	return time.Now() // no Last-Modified
	}

	func (s *fileStat) IsDir() bool {
	return false
	}

	func (s *fileStat) Sys() interface{} {
	return s.header
	}

	func statusError(res *http.Response) error {
	if res.StatusCode == http.StatusNotFound {
	return os.ErrNotExist
	}
	return errors.New(res.Status)
	}

	// Stat returns the os.FileInfo interface describing file.
	func (f *DatastoreFile) Stat() (os.FileInfo, error) {
	// TODO: consider using Datastore.Stat() instead
	u, p, err := f.d.downloadTicket(f.ctx, f.name, &soap.Download{Method: "HEAD"})
	if err != nil {
	return nil, err
	}

	res, err := f.d.Client().DownloadRequest(f.ctx, u, p)
	if err != nil {
	return nil, err
	}

	if res.StatusCode != http.StatusOK {
	return nil, statusError(res)
	}

	f.length = res.ContentLength

	return &fileStat{f, res.Header}, nil
	}

	func (f *DatastoreFile) get() (io.Reader, error) {
	if f.body != nil {
	return f.body, nil
	}

	u, p, err := f.d.downloadTicket(f.ctx, f.name, nil)
	if err != nil {
	return nil, err
	}

	if f.offset.read != 0 {
	p.Headers = map[string]string{
	"Range": fmt.Sprintf("bytes=%d-", f.offset.read),
	}
	}

	res, err := f.d.Client().DownloadRequest(f.ctx, u, p)
	if err != nil {
	return nil, err
	}

	switch res.StatusCode {
	case http.StatusOK:
	f.length = res.ContentLength
	case http.StatusPartialContent:
	var start, end int
	cr := res.Header.Get("Content-Range")
	_, err = fmt.Sscanf(cr, "bytes %d-%d/%d", &start, &end, &f.length)
	if err != nil {
	f.length = -1
	}
	case http.StatusRequestedRangeNotSatisfiable:
	// ok: Read() will return io.EOF
	default:
	return nil, statusError(res)
	}

	if f.length < 0 {
	_ = res.Body.Close()
	return nil, errors.New("unable to determine file size")
	}

	f.body = res.Body

	return f.body, nil
	}

	func lastIndexLines(s []byte, line *int, include func(l int, m string) bool) (int64, bool) {
	i := len(s) - 1
	done := false

	for i > 0 {
	o := bytes.LastIndexByte(s[:i], '\n')
	if o < 0 {
	break
	}

	msg := string(s[o+1 : i+1])
	if !include(*line, msg) {
	done = true
	break
	} else {
	i = o
	*line++
	}
	}

	return int64(i), done
	}

	// Tail seeks to the position of the last N lines of the file.
	func (f *DatastoreFile) Tail(n int) error {
	return f.TailFunc(n, func(line int, _ string) bool { return n > line })
	}

	// TailFunc will seek backwards in the datastore file until it hits a line that does
	// not satisfy the supplied `include` function.
	func (f *DatastoreFile) TailFunc(lines int, include func(line int, message string) bool) error {
	// Read the file in reverse using bsize chunks
	const bsize = int64(1024 * 16)

	fsize, err := f.Seek(0, io.SeekEnd)
	if err != nil {
	return err
	}

	if lines == 0 {
	return nil
	}

	chunk := int64(-1)

	buf := bytes.NewBuffer(make([]byte, 0, bsize))
	line := 0

	for {
	var eof bool
	var pos int64

	nread := bsize

	offset := chunk * bsize
	remain := fsize + offset

	if remain < 0 {
	if pos, err = f.Seek(0, io.SeekStart); err != nil {
	return err
	}

	nread = bsize + remain
	eof = true
	} else {
	if pos, err = f.Seek(offset, io.SeekEnd); err != nil {
	return err
	}
	}

	if _, err = io.CopyN(buf, f, nread); err != nil {
	if err != io.EOF {
	return err
	}
	}

	b := buf.Bytes()
	idx, done := lastIndexLines(b, &line, include)

	if done {
	if chunk == -1 {
	// We found all N lines in the last chunk of the file.
	// The seek offset is also now at the current end of file.
	// Save this buffer to avoid another GET request when Read() is called.
	buf.Next(int(idx + 1))
	f.buf = buf
	return nil
	}

	if _, err = f.Seek(pos+idx+1, io.SeekStart); err != nil {
	return err
	}

	break
	}

	if eof {
	if remain < 0 {
	// We found < N lines in the entire file, so seek to the start.
	_, _ = f.Seek(0, io.SeekStart)
	}
	break
	}

	chunk--
	buf.Reset()
	}

	return nil
	}

	type followDatastoreFile struct {
	r *DatastoreFile
	c chan struct{}
	i time.Duration
	o sync.Once
	}

	// Read reads up to len(b) bytes from the DatastoreFile being followed.
	// This method will block until data is read, an error other than io.EOF is returned or Close() is called.
	func (f *followDatastoreFile) Read(p []byte) (int, error) {
	offset := f.r.offset.seek
	stop := false

	for {
	n, err := f.r.Read(p)
	if err != nil && err == io.EOF {
	_ = f.r.Close() // GET request body has been drained.
	if stop {
	return n, err
	}
	err = nil
	}

	if n > 0 {
	return n, err
	}

	select {
	case <-f.c:
	// Wake up and stop polling once the body has been drained
	stop = true
	case <-time.After(f.i):
	}

	info, serr := f.r.Stat()
	if serr != nil {
	// Return EOF rather than 404 if the file goes away
	if serr == os.ErrNotExist {
	_ = f.r.Close()
	return 0, io.EOF
	}
	return 0, serr
	}

	if info.Size() < offset {
	// assume file has be truncated
	offset, err = f.r.Seek(0, io.SeekStart)
	if err != nil {
	return 0, err
	}
	}
	}
	}

	// Close will stop Follow polling and close the underlying DatastoreFile.
	func (f *followDatastoreFile) Close() error {
	f.o.Do(func() { close(f.c) })
	return nil
	}

	// Follow returns an io.ReadCloser to stream the file contents as data is appended.
	func (f *DatastoreFile) Follow(interval time.Duration) io.ReadCloser {
	return &followDatastoreFile{
	r: f,
	c: make(chan struct{}),
	i: interval,
	}
	}