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file.go
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file.go
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package vfs
import (
"context"
"errors"
"fmt"
"os"
"path"
"sync"
"sync/atomic"
"time"
"github.com/rclone/rclone/fs"
"github.com/rclone/rclone/fs/log"
"github.com/rclone/rclone/fs/operations"
"github.com/rclone/rclone/vfs/vfscommon"
)
// The File object is tightly coupled to the Dir object. Since they
// both have locks there is plenty of potential for deadlocks. In
// order to mitigate this, we use the following conventions
//
// File may **only** call these methods from Dir with the File lock
// held.
//
// Dir.Fs
// Dir.VFS
//
// (As these are read only and do not need to take the Dir mutex.)
//
// File may **not** call any other Dir methods with the File lock
// held. This preserves total lock ordering and makes File subordinate
// to Dir as far as locking is concerned, preventing deadlocks.
//
// File may **not** read any members of Dir directly.
// File represents a file
type File struct {
inode uint64 // inode number - read only
size atomic.Int64 // size of file
muRW sync.Mutex // synchronize RWFileHandle.openPending(), RWFileHandle.close() and File.Remove
mu sync.RWMutex // protects the following
d *Dir // parent directory
dPath string // path of parent directory. NB dir rename means all Files are flushed
o fs.Object // NB o may be nil if file is being written
leaf string // leaf name of the object
writers []Handle // writers for this file
virtualModTime *time.Time // modtime for backends with Precision == fs.ModTimeNotSupported
pendingModTime time.Time // will be applied once o becomes available, i.e. after file was written
pendingRenameFun func(ctx context.Context) error // will be run/renamed after all writers close
sys atomic.Value // user defined info to be attached here
nwriters atomic.Int32 // len(writers)
appendMode bool // file was opened with O_APPEND
}
// newFile creates a new File
//
// o may be nil
func newFile(d *Dir, dPath string, o fs.Object, leaf string) *File {
f := &File{
d: d,
dPath: dPath,
o: o,
leaf: leaf,
inode: newInode(),
}
if o != nil {
f.size.Store(o.Size())
}
return f
}
// 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) {
f.mu.RLock()
defer f.mu.RUnlock()
mode = f.d.vfs.Opt.FilePerms
if f.appendMode {
mode |= os.ModeAppend
}
return mode
}
// Name (base) of the directory - satisfies Node interface
func (f *File) Name() (name string) {
f.mu.RLock()
defer f.mu.RUnlock()
return f.leaf
}
// _path returns the full path of the file
// use when lock is held
func (f *File) _path() string {
return path.Join(f.dPath, f.leaf)
}
// Path returns the full path of the file
func (f *File) Path() string {
f.mu.RLock()
dPath, leaf := f.dPath, f.leaf
f.mu.RUnlock()
return path.Join(dPath, leaf)
}
// Sys returns underlying data source (can be nil) - satisfies Node interface
func (f *File) Sys() interface{} {
return f.sys.Load()
}
// SetSys sets the underlying data source (can be nil) - satisfies Node interface
func (f *File) SetSys(x interface{}) {
f.sys.Store(x)
}
// Inode returns the inode number - satisfies Node interface
func (f *File) Inode() uint64 {
return f.inode
}
// Node returns the Node associated with this - satisfies Noder interface
func (f *File) Node() Node {
return f
}
// renameDir - call when parent directory has been renamed
func (f *File) renameDir(dPath string) {
f.mu.RLock()
f.dPath = dPath
f.mu.RUnlock()
}
// applyPendingRename runs a previously set rename operation if there are no
// more remaining writers. Call without lock held.
func (f *File) applyPendingRename() {
f.mu.RLock()
fun := f.pendingRenameFun
writing := f._writingInProgress()
f.mu.RUnlock()
if fun == nil || writing {
return
}
fs.Debugf(f.Path(), "Running delayed rename now")
if err := fun(context.TODO()); err != nil {
fs.Errorf(f.Path(), "delayed File.Rename error: %v", err)
}
}
// rename attempts to immediately rename a file if there are no open writers.
// Otherwise it will queue the rename operation on the remote until no writers
// remain.
func (f *File) rename(ctx context.Context, destDir *Dir, newName string) error {
f.mu.RLock()
d := f.d
oldPendingRenameFun := f.pendingRenameFun
f.mu.RUnlock()
if features := d.Fs().Features(); features.Move == nil && features.Copy == nil {
err := fmt.Errorf("Fs %q can't rename files (no server-side Move or Copy)", d.Fs())
fs.Errorf(f.Path(), "Dir.Rename error: %v", err)
return err
}
oldPath := f.Path()
// File.mu is unlocked here to call Dir.Path()
newPath := path.Join(destDir.Path(), newName)
renameCall := func(ctx context.Context) (err error) {
// chain rename calls if any
if oldPendingRenameFun != nil {
err := oldPendingRenameFun(ctx)
if err != nil {
return err
}
}
f.mu.RLock()
o := f.o
d := f.d
f.mu.RUnlock()
var newObject fs.Object
// if o is nil then are writing the file so no need to rename the object
if o != nil {
if o.Remote() == newPath {
return nil // no need to rename
}
// do the move of the remote object
dstOverwritten, _ := d.Fs().NewObject(ctx, newPath)
newObject, err = operations.Move(ctx, d.Fs(), dstOverwritten, newPath, o)
if err != nil {
fs.Errorf(f.Path(), "File.Rename error: %v", err)
return err
}
// newObject can be nil here for example if --dry-run
if newObject == nil {
err = errors.New("rename failed: nil object returned")
fs.Errorf(f.Path(), "File.Rename %v", err)
return err
}
}
// Rename in the cache
if d.vfs.cache != nil && d.vfs.cache.Exists(oldPath) {
if err := d.vfs.cache.Rename(oldPath, newPath, newObject); err != nil {
fs.Infof(f.Path(), "File.Rename failed in Cache: %v", err)
}
}
// Update the node with the new details
fs.Debugf(f.Path(), "Updating file with %v %p", newObject, f)
// f.rename(destDir, newObject)
f.mu.Lock()
if newObject != nil {
f.o = newObject
}
f.pendingRenameFun = nil
f.mu.Unlock()
return nil
}
// rename the file object
dPath := destDir.Path()
f.mu.Lock()
f.d = destDir
f.dPath = dPath
f.leaf = newName
writing := f._writingInProgress()
f.mu.Unlock()
// Delay the rename if not using RW caching. For the minimal case we
// need to look in the cache to see if caching is in use.
CacheMode := d.vfs.Opt.CacheMode
if writing &&
(CacheMode < vfscommon.CacheModeMinimal ||
(CacheMode == vfscommon.CacheModeMinimal && !destDir.vfs.cache.Exists(oldPath))) {
fs.Debugf(oldPath, "File is currently open, delaying rename %p", f)
f.mu.Lock()
f.pendingRenameFun = renameCall
f.mu.Unlock()
return nil
}
return renameCall(ctx)
}
// addWriter adds a write handle to the file
func (f *File) addWriter(h Handle) {
f.mu.Lock()
f.writers = append(f.writers, h)
f.nwriters.Add(1)
f.mu.Unlock()
}
// delWriter removes a write handle from the file
func (f *File) delWriter(h Handle) {
f.mu.Lock()
defer f.applyPendingRename()
defer f.mu.Unlock()
var found = -1
for i := range f.writers {
if f.writers[i] == h {
found = i
break
}
}
if found >= 0 {
f.writers = append(f.writers[:found], f.writers[found+1:]...)
f.nwriters.Add(-1)
} else {
fs.Debugf(f._path(), "File.delWriter couldn't find handle")
}
}
// activeWriters returns the number of writers on the file
//
// Note that we don't take the mutex here. If we do then we can get a
// deadlock.
func (f *File) activeWriters() int {
return int(f.nwriters.Load())
}
// _roundModTime rounds the time passed in to the Precision of the
// underlying Fs
//
// It should be called with the lock held
func (f *File) _roundModTime(modTime time.Time) time.Time {
precision := f.d.f.Precision()
if precision == fs.ModTimeNotSupported {
return modTime
}
return modTime.Truncate(precision)
}
// 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.RLock()
d, o, pendingModTime, virtualModTime := f.d, f.o, f.pendingModTime, f.virtualModTime
f.mu.RUnlock()
// Set the virtual modtime up for backends which don't support setting modtime
//
// Note that we only cache modtime values that we have returned to the OS
// if we haven't returned a value to the OS then we can change it
defer func() {
if f.d.f.Precision() == fs.ModTimeNotSupported && (virtualModTime == nil || !virtualModTime.Equal(modTime)) {
f.virtualModTime = &modTime
fs.Debugf(f._path(), "Set virtual modtime to %v", f.virtualModTime)
}
}()
if d.vfs.Opt.NoModTime {
return d.ModTime()
}
// Read the modtime from a dirty item if it exists
if f.d.vfs.Opt.CacheMode >= vfscommon.CacheModeMinimal {
if item := f.d.vfs.cache.DirtyItem(f._path()); item != nil {
modTime, err := item.GetModTime()
if err != nil {
fs.Errorf(f._path(), "ModTime: Item GetModTime failed: %v", err)
} else {
return f._roundModTime(modTime)
}
}
}
if !pendingModTime.IsZero() {
return f._roundModTime(pendingModTime)
}
if virtualModTime != nil && !virtualModTime.IsZero() {
fs.Debugf(f._path(), "Returning virtual modtime %v", f.virtualModTime)
return f._roundModTime(*virtualModTime)
}
if o == nil {
return time.Now()
}
return o.ModTime(context.TODO())
}
// nonNegative returns 0 if i is -ve, i otherwise
func nonNegative(i int64) int64 {
if i >= 0 {
return i
}
return 0
}
// Size of the file
func (f *File) Size() int64 {
f.mu.RLock()
defer f.mu.RUnlock()
// Read the size from a dirty item if it exists
if f.d.vfs.Opt.CacheMode >= vfscommon.CacheModeMinimal {
if item := f.d.vfs.cache.DirtyItem(f._path()); item != nil {
size, err := item.GetSize()
if err != nil {
fs.Errorf(f._path(), "Size: Item GetSize failed: %v", err)
} else {
return size
}
}
}
// if o is nil it isn't valid yet or there are writers, so return the size so far
if f._writingInProgress() {
return f.size.Load()
}
return nonNegative(f.o.Size())
}
// SetModTime sets the modtime for the file
//
// if NoModTime is set then it does nothing
func (f *File) SetModTime(modTime time.Time) error {
f.mu.Lock()
defer f.mu.Unlock()
if f.d.vfs.Opt.NoModTime {
return nil
}
if f.d.vfs.Opt.ReadOnly {
return EROFS
}
f.pendingModTime = modTime
// set the time of the file in the cache
if f.d.vfs.cache != nil && f.d.vfs.cache.Exists(f._path()) {
f.d.vfs.cache.SetModTime(f._path(), f.pendingModTime)
}
// Only update the ModTime when there are no writers, setObject will do it
if !f._writingInProgress() {
return f._applyPendingModTime()
}
// queue up for later, hoping f.o becomes available
return nil
}
// Apply a pending mod time
// Call with the mutex held
func (f *File) _applyPendingModTime() error {
if f.pendingModTime.IsZero() {
return nil
}
defer func() { f.pendingModTime = time.Time{} }()
if f.o == nil {
return errors.New("cannot apply ModTime, file object is not available")
}
dt := f.pendingModTime.Sub(f.o.ModTime(context.Background()))
modifyWindow := f.o.Fs().Precision()
if dt < modifyWindow && dt > -modifyWindow {
fs.Debugf(f.o, "Not setting pending mod time %v as it is already set", f.pendingModTime)
return nil
}
// set the time of the object
err := f.o.SetModTime(context.TODO(), f.pendingModTime)
switch err {
case nil:
fs.Debugf(f.o, "Applied pending mod time %v OK", f.pendingModTime)
case fs.ErrorCantSetModTime, fs.ErrorCantSetModTimeWithoutDelete:
// do nothing, in order to not break "touch somefile" if it exists already
default:
fs.Errorf(f.o, "Failed to apply pending mod time %v: %v", f.pendingModTime, err)
return err
}
return nil
}
// Apply a pending mod time
func (f *File) applyPendingModTime() error {
f.mu.Lock()
defer f.mu.Unlock()
return f._applyPendingModTime()
}
// _writingInProgress returns true of there are any open writers
// Call with read lock held
func (f *File) _writingInProgress() bool {
return f.o == nil || len(f.writers) != 0
}
// writingInProgress returns true of there are any open writers
func (f *File) writingInProgress() bool {
f.mu.RLock()
defer f.mu.RUnlock()
return f.o == nil || len(f.writers) != 0
}
// Update the size while writing
func (f *File) setSize(n int64) {
f.size.Store(n)
}
// Update the object when written and add it to the directory
func (f *File) setObject(o fs.Object) {
f.mu.Lock()
f.o = o
_ = f._applyPendingModTime()
d := f.d
f.mu.Unlock()
// Release File.mu before calling Dir method
d.addObject(f)
}
// Update the object but don't update the directory cache - for use by
// the directory cache
func (f *File) setObjectNoUpdate(o fs.Object) {
f.mu.Lock()
f.o = o
f.virtualModTime = nil
fs.Debugf(f._path(), "Reset virtual modtime")
f.mu.Unlock()
}
// Get the current fs.Object - may be nil
func (f *File) getObject() fs.Object {
f.mu.RLock()
defer f.mu.RUnlock()
return f.o
}
// exists returns whether the file exists already
func (f *File) exists() bool {
f.mu.RLock()
defer f.mu.RUnlock()
return f.o != nil
}
// Wait for f.o to become non nil for a short time returning it or an
// error. Use when opening a read handle.
//
// Call without the mutex held
func (f *File) waitForValidObject() (o fs.Object, err error) {
for i := 0; i < 50; i++ {
f.mu.RLock()
o = f.o
nwriters := len(f.writers)
f.mu.RUnlock()
if o != nil {
return o, nil
}
if nwriters == 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
_, err = f.waitForValidObject()
if err != nil {
return nil, err
}
// fs.Debugf(f.Path(), "File.openRead")
fh, err = newReadFileHandle(f)
if err != nil {
fs.Debugf(f.Path(), "File.openRead failed: %v", err)
return nil, err
}
return fh, nil
}
// openWrite open the file for write
func (f *File) openWrite(flags int) (fh *WriteFileHandle, err error) {
f.mu.RLock()
d := f.d
f.mu.RUnlock()
if d.vfs.Opt.ReadOnly {
return nil, EROFS
}
// fs.Debugf(f.Path(), "File.openWrite")
fh, err = newWriteFileHandle(d, f, f.Path(), flags)
if err != nil {
fs.Debugf(f.Path(), "File.openWrite failed: %v", err)
return nil, err
}
return fh, nil
}
// openRW open the file for read and write using a temporary file
//
// It uses the open flags passed in.
func (f *File) openRW(flags int) (fh *RWFileHandle, err error) {
f.mu.RLock()
d := f.d
f.mu.RUnlock()
// FIXME chunked
if flags&accessModeMask != os.O_RDONLY && d.vfs.Opt.ReadOnly {
return nil, EROFS
}
// fs.Debugf(f.Path(), "File.openRW")
fh, err = newRWFileHandle(d, f, flags)
if err != nil {
fs.Debugf(f.Path(), "File.openRW failed: %v", err)
return nil, err
}
return fh, nil
}
// Sync the file
//
// Note that we don't do anything except return OK
func (f *File) Sync() error {
return nil
}
// Remove the file
func (f *File) Remove() (err error) {
defer log.Trace(f.Path(), "")("err=%v", &err)
f.mu.RLock()
d := f.d
f.mu.RUnlock()
if d.vfs.Opt.ReadOnly {
return EROFS
}
// Remove the object from the cache
wasWriting := false
if d.vfs.cache != nil && d.vfs.cache.Exists(f.Path()) {
wasWriting = d.vfs.cache.Remove(f.Path())
}
f.muRW.Lock() // muRW must be locked before mu to avoid
f.mu.Lock() // deadlock in RWFileHandle.openPending and .close
if f.o != nil {
err = f.o.Remove(context.TODO())
}
f.mu.Unlock()
f.muRW.Unlock()
if err != nil {
if wasWriting {
// Ignore error deleting file if was writing it as it may not be uploaded yet
err = nil
fs.Debugf(f._path(), "Ignoring File.Remove file error as uploading: %v", err)
} else {
fs.Debugf(f._path(), "File.Remove file error: %v", err)
}
}
// Remove the item from the directory listing
// called with File.mu released when there is no error removing the underlying file
if err == nil {
d.delObject(f.Name())
}
return err
}
// 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) {
f.mu.RLock()
defer f.mu.RUnlock()
return f.o
}
// Dir returns the directory this file is in
func (f *File) Dir() *Dir {
f.mu.RLock()
defer f.mu.RUnlock()
return f.d
}
// VFS returns the instance of the VFS
func (f *File) VFS() *VFS {
f.mu.RLock()
defer f.mu.RUnlock()
return f.d.vfs
}
// Fs returns the underlying Fs for the file
func (f *File) Fs() fs.Fs {
f.mu.RLock()
defer f.mu.RUnlock()
return f.d.Fs()
}
// Open a file according to the flags provided
//
// O_RDONLY open the file read-only.
// O_WRONLY open the file write-only.
// O_RDWR open the file read-write.
//
// O_APPEND append data to the file when writing.
// O_CREATE create a new file if none exists.
// O_EXCL used with O_CREATE, file must not exist
// O_SYNC open for synchronous I/O.
// O_TRUNC if possible, truncate file when opened
//
// We ignore O_SYNC and O_EXCL
func (f *File) Open(flags int) (fd Handle, err error) {
defer log.Trace(f.Path(), "flags=%s", decodeOpenFlags(flags))("fd=%v, err=%v", &fd, &err)
var (
write bool // if set need write support
read bool // if set need read support
rdwrMode = flags & accessModeMask
)
// http://pubs.opengroup.org/onlinepubs/7908799/xsh/open.html
// The result of using O_TRUNC with O_RDONLY is undefined.
// Linux seems to truncate the file, but we prefer to return EINVAL
if rdwrMode == os.O_RDONLY && flags&os.O_TRUNC != 0 {
return nil, EINVAL
}
// Figure out the read/write intents
switch {
case rdwrMode == os.O_RDONLY:
read = true
case rdwrMode == os.O_WRONLY:
write = true
case rdwrMode == os.O_RDWR:
read = true
write = true
default:
fs.Debugf(f.Path(), "Can't figure out how to open with flags: 0x%X", flags)
return nil, EPERM
}
// If append is set then set read to force openRW
if flags&os.O_APPEND != 0 {
read = true
f.mu.Lock()
f.appendMode = true
f.mu.Unlock()
}
// If truncate is set then set write to force openRW
if flags&os.O_TRUNC != 0 {
write = true
}
// If create is set then set write to force openRW
if flags&os.O_CREATE != 0 {
write = true
}
// Open the correct sort of handle
f.mu.RLock()
d := f.d
f.mu.RUnlock()
CacheMode := d.vfs.Opt.CacheMode
if CacheMode >= vfscommon.CacheModeMinimal && (d.vfs.cache.InUse(f.Path()) || d.vfs.cache.Exists(f.Path())) {
fd, err = f.openRW(flags)
} else if read && write {
if CacheMode >= vfscommon.CacheModeMinimal {
fd, err = f.openRW(flags)
} else {
// Open write only and hope the user doesn't
// want to read. If they do they will get an
// EPERM plus an Error log.
fd, err = f.openWrite(flags)
}
} else if write {
if CacheMode >= vfscommon.CacheModeWrites {
fd, err = f.openRW(flags)
} else {
fd, err = f.openWrite(flags)
}
} else if read {
if CacheMode >= vfscommon.CacheModeFull {
fd, err = f.openRW(flags)
} else {
fd, err = f.openRead()
}
} else {
fs.Debugf(f.Path(), "Can't figure out how to open with flags: 0x%X", flags)
return nil, EPERM
}
// if creating a file, add the file to the directory
if err == nil && flags&os.O_CREATE != 0 {
// called without File.mu held
d.addObject(f)
}
return fd, err
}
// Truncate changes the size of the named file.
func (f *File) Truncate(size int64) (err error) {
// make a copy of fh.writers with the lock held then unlock so
// we can call other file methods.
f.mu.Lock()
writers := make([]Handle, len(f.writers))
copy(writers, f.writers)
f.mu.Unlock()
// If have writers then call truncate for each writer
if len(writers) != 0 {
var openWriters = len(writers)
fs.Debugf(f.Path(), "Truncating %d file handles", len(writers))
for _, h := range writers {
truncateErr := h.Truncate(size)
if truncateErr == ECLOSED {
// Ignore ECLOSED since file handle can get closed while this is running
openWriters--
} else if truncateErr != nil {
err = truncateErr
}
}
// If at least one open writer return here
if openWriters > 0 {
return err
}
}
// if o is nil it isn't valid yet
o, err := f.waitForValidObject()
if err != nil {
return err
}
// If no writers, and size is already correct then all done
if o.Size() == size {
return nil
}
fs.Debugf(f.Path(), "Truncating file")
// Otherwise if no writers then truncate the file by opening
// the file and truncating it.
flags := os.O_WRONLY
if size == 0 {
flags |= os.O_TRUNC
}
fh, err := f.Open(flags)
if err != nil {
return err
}
defer fs.CheckClose(fh, &err)
if size != 0 {
return fh.Truncate(size)
}
return nil
}