mirror of
https://github.com/rclone/rclone.git
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c19e675ca6
Without this fix the cached file can be removed as the file is being uploaded or downloaded. This can cause the directory listings to become inconsistent (this issue) or data loss (if a retry was needed in the Copy). Remove file needs to be excluded from running at the same time as both openPending and close so it makes sense to unify the locking between all 3.
555 lines
13 KiB
Go
555 lines
13 KiB
Go
package vfs
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import (
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"os"
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"path"
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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/ncw/rclone/fs/log"
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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.Mutex // protects the following
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o fs.Object // NB o may be nil if file is being written
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leaf string // leaf name of the object
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rwOpenCount int // number of open files on this handle
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writers []Handle // writers for this file
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nwriters int32 // len(writers) which is read/updated with atomic
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readWriters int // how many RWFileHandle are open for writing
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readWriterClosing bool // is a RWFileHandle currently cosing?
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modified bool // has the cache file be modified by a RWFileHandle?
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pendingModTime time.Time // will be applied once o becomes available, i.e. after file was written
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muRW sync.Mutex // synchonize RWFileHandle.openPending(), RWFileHandle.close() and File.Remove
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}
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// newFile creates a new File
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func newFile(d *Dir, o fs.Object, leaf string) *File {
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return &File{
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d: d,
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o: o,
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leaf: leaf,
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inode: newInode(),
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}
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}
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// String converts it to printable
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func (f *File) String() string {
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if f == nil {
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return "<nil *File>"
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}
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return f.Path()
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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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// IsDir returns false for File - satisfies Node interface
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func (f *File) IsDir() bool {
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return false
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}
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// Mode bits of the file or directory - satisfies Node interface
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func (f *File) Mode() (mode os.FileMode) {
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return f.d.vfs.Opt.FilePerms
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}
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// Name (base) of the directory - satisfies Node interface
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func (f *File) Name() (name string) {
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return f.leaf
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}
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// Path returns the full path of the file
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func (f *File) Path() string {
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return path.Join(f.d.path, f.leaf)
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}
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// Sys returns underlying data source (can be nil) - satisfies Node interface
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func (f *File) Sys() interface{} {
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return nil
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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 the internals 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.leaf = path.Base(o.Remote())
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f.mu.Unlock()
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}
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// addWriter adds a write handle to the file
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func (f *File) addWriter(h Handle) {
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f.mu.Lock()
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f.writers = append(f.writers, h)
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atomic.AddInt32(&f.nwriters, 1)
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if _, ok := h.(*RWFileHandle); ok {
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f.readWriters++
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}
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f.mu.Unlock()
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}
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// delWriter removes a write handle from the file
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func (f *File) delWriter(h Handle, modifiedCacheFile bool) (lastWriterAndModified bool) {
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f.mu.Lock()
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defer f.mu.Unlock()
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var found = -1
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for i := range f.writers {
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if f.writers[i] == h {
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found = i
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break
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}
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}
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if found >= 0 {
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f.writers = append(f.writers[:found], f.writers[found+1:]...)
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atomic.AddInt32(&f.nwriters, -1)
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} else {
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fs.Debugf(f.o, "File.delWriter couldn't find handle")
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}
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if _, ok := h.(*RWFileHandle); ok {
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f.readWriters--
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}
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f.readWriterClosing = true
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if modifiedCacheFile {
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f.modified = true
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}
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lastWriterAndModified = len(f.writers) == 0 && f.modified
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if lastWriterAndModified {
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f.modified = false
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}
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return
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}
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// addRWOpen should be called by ReadWriteHandle when they have
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// actually opened the file for read or write.
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func (f *File) addRWOpen() {
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f.mu.Lock()
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f.rwOpenCount++
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f.mu.Unlock()
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}
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// delRWOpen should be called by ReadWriteHandle when they have closed
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// an actually opene file for read or write.
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func (f *File) delRWOpen() {
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f.mu.Lock()
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f.rwOpenCount--
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f.mu.Unlock()
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}
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// rwOpens returns how many active open ReadWriteHandles there are.
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// Note that file handles which are in pending open state aren't
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// counted.
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func (f *File) rwOpens() int {
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f.mu.Lock()
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defer f.mu.Unlock()
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return f.rwOpenCount
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}
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// finishWriterClose resets the readWriterClosing flag
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func (f *File) finishWriterClose() {
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f.mu.Lock()
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f.readWriterClosing = false
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f.mu.Unlock()
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}
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// activeWriters returns the number of writers on the file
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//
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// Note that we don't take the mutex here. If we do then we can get a
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// deadlock.
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func (f *File) activeWriters() int {
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return int(atomic.LoadInt32(&f.nwriters))
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}
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// ModTime returns the modified time of the file
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//
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// if NoModTime is set then it returns the mod time of the directory
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func (f *File) ModTime() (modTime time.Time) {
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f.mu.Lock()
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defer f.mu.Unlock()
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if !f.d.vfs.Opt.NoModTime {
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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 || len(f.writers) != 0 || f.readWriterClosing {
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if !f.pendingModTime.IsZero() {
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return f.pendingModTime
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}
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} else {
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return f.o.ModTime()
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}
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}
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return f.d.modTime
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}
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// nonNegative returns 0 if i is -ve, i otherwise
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func nonNegative(i int64) int64 {
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if i >= 0 {
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return i
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}
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return 0
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}
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// Size of the file
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func (f *File) Size() int64 {
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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 || len(f.writers) != 0 || f.readWriterClosing {
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return atomic.LoadInt64(&f.size)
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}
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return nonNegative(f.o.Size())
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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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if f.d.vfs.Opt.ReadOnly {
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return EROFS
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}
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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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// Only update the ModTime when there are no writers, setObject will do it
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if f.o != nil && len(f.writers) == 0 && !f.readWriterClosing {
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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, fs.ErrorCantSetModTimeWithoutDelete:
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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, "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 and add it to the directory
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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(f)
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}
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// Update the object but don't update the directory cache - for use by
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// the directory cache
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func (f *File) setObjectNoUpdate(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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}
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// Get the current fs.Object - may be nil
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func (f *File) getObject() fs.Object {
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f.mu.Lock()
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defer f.mu.Unlock()
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return f.o
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}
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// exists returns whether the file exists already
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func (f *File) exists() bool {
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f.mu.Lock()
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defer f.mu.Unlock()
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return f.o != nil
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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. Use when opening a read handle.
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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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nwriters := len(f.writers)
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wclosing := f.readWriterClosing
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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 nwriters == 0 && !wclosing {
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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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_, 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)
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if err != nil {
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fs.Errorf(f, "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(flags int) (fh *WriteFileHandle, err error) {
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if f.d.vfs.Opt.ReadOnly {
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return nil, EROFS
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}
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// fs.Debugf(o, "File.openWrite")
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fh, err = newWriteFileHandle(f.d, f, f.Path(), flags)
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if err != nil {
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fs.Errorf(f, "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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// openRW open the file for read and write using a temporay file
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//
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// It uses the open flags passed in.
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func (f *File) openRW(flags int) (fh *RWFileHandle, err error) {
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// FIXME chunked
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if flags&accessModeMask != os.O_RDONLY && f.d.vfs.Opt.ReadOnly {
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return nil, EROFS
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}
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// fs.Debugf(o, "File.openRW")
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fh, err = newRWFileHandle(f.d, f, f.Path(), flags)
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if err != nil {
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fs.Errorf(f, "File.openRW 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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// Sync 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) Sync() error {
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return nil
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}
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// Remove the file
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func (f *File) Remove() error {
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f.muRW.Lock()
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defer f.muRW.Unlock()
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if f.d.vfs.Opt.ReadOnly {
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return EROFS
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}
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if f.o != nil {
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err := f.o.Remove()
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if err != nil {
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fs.Errorf(f, "File.Remove file error: %v", err)
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return err
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}
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}
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// Remove the item from the directory listing
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f.d.delObject(f.Name())
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// Remove the object from the cache
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if f.d.vfs.Opt.CacheMode >= CacheModeMinimal {
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f.d.vfs.cache.remove(f.Path())
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}
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return nil
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}
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// RemoveAll the file - same as remove for files
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func (f *File) RemoveAll() error {
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return f.Remove()
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}
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// DirEntry returns the underlying fs.DirEntry - may be nil
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func (f *File) DirEntry() (entry fs.DirEntry) {
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return f.o
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}
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// Dir returns the directory this file is in
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func (f *File) Dir() *Dir {
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return f.d
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}
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// VFS returns the instance of the VFS
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func (f *File) VFS() *VFS {
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return f.d.vfs
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}
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// Open a file according to the flags provided
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//
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// O_RDONLY open the file read-only.
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// O_WRONLY open the file write-only.
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// O_RDWR open the file read-write.
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//
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// O_APPEND append data to the file when writing.
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// O_CREATE create a new file if none exists.
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// O_EXCL used with O_CREATE, file must not exist
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// O_SYNC open for synchronous I/O.
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// O_TRUNC if possible, truncate file when opene
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//
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// We ignore O_SYNC and O_EXCL
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func (f *File) Open(flags int) (fd Handle, err error) {
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defer log.Trace(f, "flags=%s", decodeOpenFlags(flags))("fd=%v, err=%v", &fd, &err)
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var (
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write bool // if set need write support
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read bool // if set need read support
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rdwrMode = flags & accessModeMask
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)
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// http://pubs.opengroup.org/onlinepubs/7908799/xsh/open.html
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// The result of using O_TRUNC with O_RDONLY is undefined.
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// Linux seems to truncate the file, but we prefer to return EINVAL
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if rdwrMode == os.O_RDONLY && flags&os.O_TRUNC != 0 {
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return nil, EINVAL
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}
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// Figure out the read/write intents
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switch {
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case rdwrMode == os.O_RDONLY:
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read = true
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case rdwrMode == os.O_WRONLY:
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write = true
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case rdwrMode == os.O_RDWR:
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read = true
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write = true
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default:
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fs.Errorf(f, "Can't figure out how to open with flags: 0x%X", flags)
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return nil, EPERM
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}
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// If append is set then set read to force openRW
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if flags&os.O_APPEND != 0 {
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read = true
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}
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// If truncate is set then set write to force openRW
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if flags&os.O_TRUNC != 0 {
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write = true
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}
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// FIXME discover if file is in cache or not?
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// Open the correct sort of handle
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CacheMode := f.d.vfs.Opt.CacheMode
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opens := f.d.vfs.cache.opens(f.Path())
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if CacheMode >= CacheModeMinimal && opens > 0 {
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fd, err = f.openRW(flags)
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} else if read && write {
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if CacheMode >= CacheModeMinimal {
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fd, err = f.openRW(flags)
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} else {
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// Open write only and hope the user doesn't
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// want to read. If they do they will get an
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// EPERM plus an Error log.
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fd, err = f.openWrite(flags)
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}
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} else if write {
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if CacheMode >= CacheModeWrites {
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fd, err = f.openRW(flags)
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} else {
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fd, err = f.openWrite(flags)
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}
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} else if read {
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if CacheMode >= CacheModeFull {
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fd, err = f.openRW(flags)
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} else {
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fd, err = f.openRead()
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}
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} else {
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fs.Errorf(f, "Can't figure out how to open with flags: 0x%X", flags)
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return nil, EPERM
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}
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return fd, err
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}
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// Truncate changes the size of the named file.
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func (f *File) Truncate(size int64) (err error) {
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// make a copy of fh.writers with the lock held then unlock so
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// we can call other file methods.
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f.mu.Lock()
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writers := make([]Handle, len(f.writers))
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copy(writers, f.writers)
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f.mu.Unlock()
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// FIXME: handle closing writer
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// If have writers then call truncate for each writer
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if len(writers) != 0 {
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fs.Debugf(f.o, "Truncating %d file handles", len(writers))
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for _, h := range writers {
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truncateErr := h.Truncate(size)
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if truncateErr != nil {
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err = truncateErr
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}
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}
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return err
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}
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fs.Debugf(f.o, "Truncating file")
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// Otherwise if no writers then truncate the file by opening
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// the file and truncating it.
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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
|
|
}
|