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204 lines
4.6 KiB
Go
204 lines
4.6 KiB
Go
package mountlib
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import (
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"sync"
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"sync/atomic"
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"time"
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"github.com/ncw/rclone/fs"
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"github.com/pkg/errors"
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)
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// File represents a file
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type File struct {
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inode uint64 // inode number
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size int64 // size of file - read and written with atomic int64 - must be 64 bit aligned
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d *Dir // parent directory - read only
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mu sync.RWMutex // protects the following
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o fs.Object // NB o may be nil if file is being written
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writers int // number of writers for this file
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pendingModTime time.Time // will be applied once o becomes available, i.e. after file was written
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}
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// newFile creates a new File
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func newFile(d *Dir, o fs.Object) *File {
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return &File{
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d: d,
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o: o,
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inode: NewInode(),
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}
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}
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// IsFile returns true for File - satisfies Node interface
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func (f *File) IsFile() bool {
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return true
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}
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// Inode returns the inode number - satisfies Node interface
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func (f *File) Inode() uint64 {
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return f.inode
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}
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// Node returns the Node assocuated with this - satisfies Noder interface
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func (f *File) Node() Node {
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return f
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}
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// rename should be called to update f.o and f.d after a rename
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func (f *File) rename(d *Dir, o fs.Object) {
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f.mu.Lock()
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f.o = o
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f.d = d
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f.mu.Unlock()
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}
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// addWriters increments or decrements the writers
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func (f *File) addWriters(n int) {
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f.mu.Lock()
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f.writers += n
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f.mu.Unlock()
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}
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// Attr fills out the attributes for the file
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func (f *File) Attr(noModTime bool) (modTime time.Time, Size, Blocks uint64, err error) {
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f.mu.Lock()
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defer f.mu.Unlock()
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// if o is nil it isn't valid yet or there are writers, so return the size so far
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if f.o == nil || f.writers != 0 {
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Size = uint64(atomic.LoadInt64(&f.size))
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if !noModTime && !f.pendingModTime.IsZero() {
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modTime = f.pendingModTime
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}
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} else {
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Size = uint64(f.o.Size())
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if !noModTime {
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modTime = f.o.ModTime()
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}
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}
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Blocks = (Size + 511) / 512
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fs.Debugf(f.o, "File.Attr modTime=%v, Size=%d, Blocks=%v", modTime, Size, Blocks)
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return
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}
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// SetModTime sets the modtime for the file
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func (f *File) SetModTime(modTime time.Time) error {
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f.mu.Lock()
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defer f.mu.Unlock()
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f.pendingModTime = modTime
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if f.o != nil {
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return f.applyPendingModTime()
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}
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// queue up for later, hoping f.o becomes available
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return nil
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}
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// call with the mutex held
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func (f *File) applyPendingModTime() error {
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defer func() { f.pendingModTime = time.Time{} }()
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if f.pendingModTime.IsZero() {
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return nil
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}
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if f.o == nil {
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return errors.New("Cannot apply ModTime, file object is not available")
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}
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err := f.o.SetModTime(f.pendingModTime)
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switch err {
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case nil:
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fs.Debugf(f.o, "File.applyPendingModTime OK")
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case fs.ErrorCantSetModTime:
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// do nothing, in order to not break "touch somefile" if it exists already
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default:
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fs.Errorf(f.o, "File.applyPendingModTime error: %v", err)
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return err
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}
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return nil
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}
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// Update the size while writing
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func (f *File) setSize(n int64) {
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atomic.StoreInt64(&f.size, n)
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}
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// Update the object when written
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func (f *File) setObject(o fs.Object) {
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f.mu.Lock()
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defer f.mu.Unlock()
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f.o = o
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_ = f.applyPendingModTime()
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f.d.addObject(o, f)
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}
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// Wait for f.o to become non nil for a short time returning it or an
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// error
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//
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// Call without the mutex held
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func (f *File) waitForValidObject() (o fs.Object, err error) {
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for i := 0; i < 50; i++ {
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f.mu.Lock()
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o = f.o
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writers := f.writers
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f.mu.Unlock()
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if o != nil {
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return o, nil
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}
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if writers == 0 {
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return nil, errors.New("can't open file - writer failed")
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}
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time.Sleep(100 * time.Millisecond)
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}
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return nil, ENOENT
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}
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// OpenRead open the file for read
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func (f *File) OpenRead() (fh *ReadFileHandle, err error) {
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// if o is nil it isn't valid yet
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o, err := f.waitForValidObject()
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if err != nil {
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return nil, err
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}
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fs.Debugf(o, "File.OpenRead")
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fh, err = newReadFileHandle(f, o, f.d.fsys.noSeek)
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err = errors.Wrap(err, "open for read")
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if err != nil {
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fs.Errorf(o, "File.OpenRead failed: %v", err)
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return nil, err
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}
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return fh, nil
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}
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// OpenWrite open the file for write
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func (f *File) OpenWrite() (fh *WriteFileHandle, err error) {
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// if o is nil it isn't valid yet
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o, err := f.waitForValidObject()
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if err != nil {
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return nil, err
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}
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fs.Debugf(o, "File.OpenWrite")
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src := newCreateInfo(f.d.f, o.Remote())
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fh, err = newWriteFileHandle(f.d, f, src)
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err = errors.Wrap(err, "open for write")
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if err != nil {
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fs.Errorf(o, "File.OpenWrite failed: %v", err)
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return nil, err
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}
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return fh, nil
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}
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// Fsync the file
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//
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// Note that we don't do anything except return OK
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func (f *File) Fsync() error {
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return nil
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}
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