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authorJakob Unterwurzacher2016-07-02 15:33:48 +0200
committerJakob Unterwurzacher2016-07-02 15:35:06 +0200
commit04ad0635159150409252f6901463768008802221 (patch)
treec9cfe215fef896916cabeee130159e48077d3968 /internal/fusefrontend/file_allocate_truncate.go
parent7b22b426b9f5e68a0ff51799e04f193dc74586d0 (diff)
fusefronted: move Truncate() and Allocate() to their own file
These are large complicated implementations that will share some code.
Diffstat (limited to 'internal/fusefrontend/file_allocate_truncate.go')
-rw-r--r--internal/fusefrontend/file_allocate_truncate.go123
1 files changed, 123 insertions, 0 deletions
diff --git a/internal/fusefrontend/file_allocate_truncate.go b/internal/fusefrontend/file_allocate_truncate.go
new file mode 100644
index 0000000..5be7df4
--- /dev/null
+++ b/internal/fusefrontend/file_allocate_truncate.go
@@ -0,0 +1,123 @@
+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
+ }
+}