rclone/vfs/file.go

455 lines
10 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 []Handle // 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(),
}
}
// 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
}
// Path returns the full path of the file
func (f *File) Path() string {
return path.Join(f.d.path, 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()
}
// addWriter adds a write handle to the file
func (f *File) addWriter(h Handle) {
f.mu.Lock()
f.writers = append(f.writers, h)
f.mu.Unlock()
}
// delWriter removes a write handle from the file
func (f *File) delWriter(h Handle) {
f.mu.Lock()
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:]...)
} else {
fs.Debugf(f.o, "File.delWriter couldn't find handle")
}
f.mu.Unlock()
}
// activeWriters returns the number of writers on the file
func (f *File) activeWriters() int {
f.mu.Lock()
defer f.mu.Unlock()
return len(f.writers)
}
// 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 || len(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 || len(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 and add it to the directory
func (f *File) setObject(o fs.Object) {
f.mu.Lock()
defer f.mu.Unlock()
f.o = o
_ = f.applyPendingModTime()
f.d.addObject(f)
}
// exists returns whether the file exists already
func (f *File) exists() bool {
f.mu.Lock()
defer f.mu.Unlock()
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.Lock()
o = f.o
nwriters := len(f.writers)
f.mu.Unlock()
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
o, err := f.waitForValidObject()
if err != nil {
return nil, err
}
// fs.Debugf(o, "File.OpenRead")
fh, err = newReadFileHandle(f, o)
if err != nil {
err = errors.Wrap(err, "open for read")
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")
fh, err = newWriteFileHandle(f.d, f, f.Path())
if err != nil {
err = errors.Wrap(err, "open for write")
fs.Errorf(f, "File.OpenWrite failed: %v", err)
return nil, err
}
return fh, nil
}
// OpenRW open the file for read and write using a temporay file
//
// It uses the open flags passed in.
func (f *File) OpenRW(flags int) (fh *RWFileHandle, err error) {
if flags&accessModeMask != os.O_RDONLY && f.d.vfs.Opt.ReadOnly {
return nil, EROFS
}
// fs.Debugf(o, "File.OpenRW")
fh, err = newRWFileHandle(f.d, f, f.Path(), flags)
if err != nil {
err = errors.Wrap(err, "open for read write")
fs.Errorf(f, "File.OpenRW 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
//
// 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 opene
//
// We ignore O_SYNC and O_EXCL
func (f *File) Open(flags int) (fd Handle, err error) {
defer fs.Trace(f, "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 & (os.O_RDONLY | os.O_WRONLY | os.O_RDWR)
)
// 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.Errorf(f, "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
}
// If truncate is set then set write to force OpenRW
if flags&os.O_TRUNC != 0 {
write = true
}
// FIXME discover if file is in cache or not?
// Open the correct sort of handle
CacheMode := f.d.vfs.Opt.CacheMode
if read && write {
if CacheMode >= 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()
}
} else if write {
if CacheMode >= CacheModeWrites {
fd, err = f.OpenRW(flags)
} else {
fd, err = f.OpenWrite()
}
} else if read {
if CacheMode >= CacheModeFull {
fd, err = f.OpenRW(flags)
} else {
fd, err = f.OpenRead()
}
} else {
fs.Errorf(f, "Can't figure out how to open with flags: 0x%X", flags)
return nil, EPERM
}
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 {
fs.Debugf(f.o, "Truncating %d file handles", len(writers))
for _, h := range writers {
truncateErr := h.Truncate(size)
if truncateErr != nil {
err = truncateErr
}
}
return err
}
fs.Debugf(f.o, "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
}