124 lines
3.6 KiB
Go
124 lines
3.6 KiB
Go
package fusefrontend
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// FUSE operations Truncate and Allocate on file handles
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// i.e. ftruncate and fallocate
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import (
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"sync"
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"syscall"
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"github.com/hanwen/go-fuse/fuse"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// Only warn once
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var allocateWarnOnce sync.Once
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// Allocate - FUSE call, fallocate(2)
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// This is not implemented yet in gocryptfs, but it is neither in EncFS. This
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// suggests that the user demand is low.
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func (f *file) Allocate(off uint64, sz uint64, mode uint32) fuse.Status {
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allocateWarnOnce.Do(func() {
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tlog.Warn.Printf("fallocate(2) is not supported, returning ENOSYS - see https://github.com/rfjakob/gocryptfs/issues/1")
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})
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return fuse.ENOSYS
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}
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// Truncate - FUSE call
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func (f *file) Truncate(newSize uint64) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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if f.released {
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// The file descriptor has been closed concurrently.
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tlog.Warn.Printf("ino%d fh%d: Truncate on released file", f.ino, f.intFd())
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return fuse.EBADF
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}
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wlock.lock(f.ino)
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defer wlock.unlock(f.ino)
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var err error
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// Common case first: Truncate to zero
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if newSize == 0 {
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err = syscall.Ftruncate(int(f.fd.Fd()), 0)
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if err != nil {
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tlog.Warn.Printf("ino%d fh%d: Ftruncate(fd, 0) returned error: %v", f.ino, f.intFd(), err)
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return fuse.ToStatus(err)
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}
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// Truncate to zero kills the file header
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f.header = nil
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return fuse.OK
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}
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// We need the old file size to determine if we are growing or shrinking
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// the file
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fi, err := f.fd.Stat()
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if err != nil {
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tlog.Warn.Printf("ino%d fh%d: Truncate: Fstat failed: %v", f.ino, f.intFd(), err)
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return fuse.ToStatus(err)
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}
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oldSize := f.contentEnc.CipherSizeToPlainSize(uint64(fi.Size()))
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{
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oldB := float32(oldSize) / float32(f.contentEnc.PlainBS())
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newB := float32(newSize) / float32(f.contentEnc.PlainBS())
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tlog.Debug.Printf("ino%d: FUSE Truncate from %.2f to %.2f blocks (%d to %d bytes)", f.ino, oldB, newB, oldSize, newSize)
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}
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// File size stays the same - nothing to do
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if newSize == oldSize {
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return fuse.OK
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}
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// File grows
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if newSize > oldSize {
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// File was empty, create new header
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if oldSize == 0 {
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err = f.createHeader()
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if err != nil {
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return fuse.ToStatus(err)
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}
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}
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// New blocks to add
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addBlocks := f.contentEnc.ExplodePlainRange(oldSize, newSize-oldSize)
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if len(addBlocks) >= 2 {
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f.zeroPad(oldSize)
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}
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lastBlock := addBlocks[len(addBlocks)-1]
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if lastBlock.IsPartial() {
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off := lastBlock.BlockPlainOff()
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_, status := f.doWrite(make([]byte, lastBlock.Length), int64(off+lastBlock.Skip))
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return status
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} else {
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off := lastBlock.BlockCipherOff()
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err = syscall.Ftruncate(f.intFd(), int64(off+f.contentEnc.CipherBS()))
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if err != nil {
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tlog.Warn.Printf("Truncate: grow Ftruncate returned error: %v", err)
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}
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return fuse.ToStatus(err)
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}
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} else {
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// File shrinks
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blockNo := f.contentEnc.PlainOffToBlockNo(newSize)
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cipherOff := f.contentEnc.BlockNoToCipherOff(blockNo)
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plainOff := f.contentEnc.BlockNoToPlainOff(blockNo)
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lastBlockLen := newSize - plainOff
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var data []byte
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if lastBlockLen > 0 {
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var status fuse.Status
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data, status = f.doRead(plainOff, lastBlockLen)
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if status != fuse.OK {
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tlog.Warn.Printf("Truncate: shrink doRead returned error: %v", err)
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return status
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}
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}
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// Truncate down to the last complete block
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err = syscall.Ftruncate(int(f.fd.Fd()), int64(cipherOff))
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if err != nil {
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tlog.Warn.Printf("Truncate: shrink Ftruncate returned error: %v", err)
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return fuse.ToStatus(err)
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}
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// Append partial block
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if lastBlockLen > 0 {
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_, status := f.doWrite(data, int64(plainOff))
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return status
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}
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return fuse.OK
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}
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}
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