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