rclone/vfs/file.go

315 lines
6.8 KiB
Go

package vfs
import (
"os"
"path"
"sync"
"sync/atomic"
"time"
"github.com/ncw/rclone/fs"
"github.com/pkg/errors"
)
// File represents a file
type File struct {
inode uint64 // inode number
size int64 // size of file - read and written with atomic int64 - must be 64 bit aligned
d *Dir // parent directory - read only
mu sync.RWMutex // protects the following
o fs.Object // NB o may be nil if file is being written
leaf string // leaf name of the object
writers int // number of writers for this file
pendingModTime time.Time // will be applied once o becomes available, i.e. after file was written
}
// newFile creates a new File
func newFile(d *Dir, o fs.Object, leaf string) *File {
return &File{
d: d,
o: o,
leaf: leaf,
inode: newInode(),
}
}
// path returns the full path of the file
func (f *File) path() string {
return path.Join(f.d.path, f.leaf)
}
// String converts it to printable
func (f *File) String() string {
if f == nil {
return "<nil *File>"
}
return f.path()
}
// IsFile returns true for File - satisfies Node interface
func (f *File) IsFile() bool {
return true
}
// IsDir returns false for File - satisfies Node interface
func (f *File) IsDir() bool {
return false
}
// Mode bits of the file or directory - satisfies Node interface
func (f *File) Mode() (mode os.FileMode) {
return f.d.vfs.Opt.FilePerms
}
// Name (base) of the directory - satisfies Node interface
func (f *File) Name() (name string) {
return f.leaf
}
// Sys returns underlying data source (can be nil) - satisfies Node interface
func (f *File) Sys() interface{} {
return nil
}
// Inode returns the inode number - satisfies Node interface
func (f *File) Inode() uint64 {
return f.inode
}
// Node returns the Node assocuated with this - satisfies Noder interface
func (f *File) Node() Node {
return f
}
// rename should be called to update the internals after a rename
func (f *File) rename(d *Dir, o fs.Object) {
f.mu.Lock()
f.o = o
f.d = d
f.leaf = path.Base(o.Remote())
f.mu.Unlock()
}
// addWriters increments or decrements the writers
func (f *File) addWriters(n int) {
f.mu.Lock()
f.writers += n
f.mu.Unlock()
}
// ModTime returns the modified time of the file
//
// if NoModTime is set then it returns the mod time of the directory
func (f *File) ModTime() (modTime time.Time) {
f.mu.Lock()
defer f.mu.Unlock()
if !f.d.vfs.Opt.NoModTime {
// if o is nil it isn't valid yet or there are writers, so return the size so far
if f.o == nil || f.writers != 0 {
if !f.pendingModTime.IsZero() {
return f.pendingModTime
}
} else {
return f.o.ModTime()
}
}
return f.d.modTime
}
// Size of the file
func (f *File) Size() int64 {
f.mu.Lock()
defer f.mu.Unlock()
// if o is nil it isn't valid yet or there are writers, so return the size so far
if f.o == nil || f.writers != 0 {
return atomic.LoadInt64(&f.size)
}
return f.o.Size()
}
// SetModTime sets the modtime for the file
func (f *File) SetModTime(modTime time.Time) error {
if f.d.vfs.Opt.ReadOnly {
return EROFS
}
f.mu.Lock()
defer f.mu.Unlock()
f.pendingModTime = modTime
if f.o != nil {
return f.applyPendingModTime()
}
// queue up for later, hoping f.o becomes available
return nil
}
// call with the mutex held
func (f *File) applyPendingModTime() error {
defer func() { f.pendingModTime = time.Time{} }()
if f.pendingModTime.IsZero() {
return nil
}
if f.o == nil {
return errors.New("Cannot apply ModTime, file object is not available")
}
err := f.o.SetModTime(f.pendingModTime)
switch err {
case nil:
fs.Debugf(f.o, "File.applyPendingModTime OK")
case fs.ErrorCantSetModTime, fs.ErrorCantSetModTimeWithoutDelete:
// do nothing, in order to not break "touch somefile" if it exists already
default:
fs.Errorf(f, "File.applyPendingModTime error: %v", err)
return err
}
return nil
}
// Update the size while writing
func (f *File) setSize(n int64) {
atomic.StoreInt64(&f.size, n)
}
// Update the object when written
func (f *File) setObject(o fs.Object) {
f.mu.Lock()
defer f.mu.Unlock()
f.o = o
_ = f.applyPendingModTime()
f.d.addObject(f)
}
// Wait for f.o to become non nil for a short time returning it or an
// error
//
// Call without the mutex held
func (f *File) waitForValidObject() (o fs.Object, err error) {
for i := 0; i < 50; i++ {
f.mu.Lock()
o = f.o
writers := f.writers
f.mu.Unlock()
if o != nil {
return o, nil
}
if writers == 0 {
return nil, errors.New("can't open file - writer failed")
}
time.Sleep(100 * time.Millisecond)
}
return nil, ENOENT
}
// OpenRead open the file for read
func (f *File) OpenRead() (fh *ReadFileHandle, err error) {
// if o is nil it isn't valid yet
o, err := f.waitForValidObject()
if err != nil {
return nil, err
}
// fs.Debugf(o, "File.OpenRead")
fh, err = newReadFileHandle(f, o)
err = errors.Wrap(err, "open for read")
if err != nil {
fs.Errorf(f, "File.OpenRead failed: %v", err)
return nil, err
}
return fh, nil
}
// OpenWrite open the file for write
func (f *File) OpenWrite() (fh *WriteFileHandle, err error) {
if f.d.vfs.Opt.ReadOnly {
return nil, EROFS
}
// fs.Debugf(o, "File.OpenWrite")
src := newCreateInfo(f.d.f, f.path())
fh, err = newWriteFileHandle(f.d, f, src)
err = errors.Wrap(err, "open for write")
if err != nil {
fs.Errorf(f, "File.OpenWrite failed: %v", err)
return nil, err
}
return fh, nil
}
// Fsync the file
//
// Note that we don't do anything except return OK
func (f *File) Fsync() error {
return nil
}
// Remove the file
func (f *File) Remove() error {
if f.d.vfs.Opt.ReadOnly {
return EROFS
}
if f.o != nil {
err := f.o.Remove()
if err != nil {
fs.Errorf(f, "File.Remove file error: %v", err)
return err
}
}
// Remove the item from the directory listing
f.d.delObject(f.Name())
return nil
}
// RemoveAll the file - same as remove for files
func (f *File) RemoveAll() error {
return f.Remove()
}
// DirEntry returns the underlying fs.DirEntry - may be nil
func (f *File) DirEntry() (entry fs.DirEntry) {
return f.o
}
// Dir returns the directory this file is in
func (f *File) Dir() *Dir {
return f.d
}
// VFS returns the instance of the VFS
func (f *File) VFS() *VFS {
return f.d.vfs
}
// Open a file according to the flags provided
func (f *File) Open(flags int) (fd Handle, err error) {
rdwrMode := flags & (os.O_RDONLY | os.O_WRONLY | os.O_RDWR)
var read bool
switch {
case rdwrMode == os.O_RDONLY:
read = true
case rdwrMode == os.O_WRONLY || (rdwrMode == os.O_RDWR && (flags&os.O_TRUNC) != 0):
read = false
case rdwrMode == os.O_RDWR:
fs.Errorf(f, "Can't open for Read and Write")
return nil, EPERM
default:
fs.Errorf(f, "Can't figure out how to open with flags: 0x%X", flags)
return nil, EPERM
}
if read {
fd, err = f.OpenRead()
} else {
fd, err = f.OpenWrite()
}
return fd, err
}