diff options
Diffstat (limited to 'internal/fusefrontend/file_holes.go')
| -rw-r--r-- | internal/fusefrontend/file_holes.go | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go index ff626d1..5b7a244 100644 --- a/internal/fusefrontend/file_holes.go +++ b/internal/fusefrontend/file_holes.go @@ -8,17 +8,35 @@ import ( "github.com/rfjakob/gocryptfs/internal/tlog" ) -// Will a write to plaintext offset "off" create a file hole in the ciphertext? -func (f *file) createsCiphertextHole(plainSize uint64, off int64) bool { +// Will a write to plaintext offset "targetOff" create a file hole in the +// ciphertext? If yes, zero-pad the last ciphertext block. +func (f *file) writePadHole(targetOff int64) fuse.Status { + // Get the current file size. + fi, err := f.fd.Stat() + if err != nil { + tlog.Warn.Printf("checkAndPadHole: Fstat failed: %v", err) + return fuse.ToStatus(err) + } + plainSize := f.contentEnc.CipherSizeToPlainSize(uint64(fi.Size())) // Appending a single byte to the file (equivalent to writing to // offset=plainSize) would write to "nextBlock". nextBlock := f.contentEnc.PlainOffToBlockNo(plainSize) // targetBlock is the block the user wants to write to. - targetBlock := f.contentEnc.PlainOffToBlockNo(uint64(off)) - // If the write goes past the next block, nextBlock will have - // to be zero-padded to the block boundary and at least nextBlock+1 - // becomes a file hole in the ciphertext. - return targetBlock > nextBlock + targetBlock := f.contentEnc.PlainOffToBlockNo(uint64(targetOff)) + // The write goes into an existing block or (if the last block was full) + // starts a new one directly after the last block. Nothing to do. + if targetBlock <= nextBlock { + return fuse.OK + } + // The write goes past the next block. nextBlock has + // to be zero-padded to the block boundary and (at least) nextBlock+1 + // will become a file hole in the ciphertext. + status := f.zeroPad(plainSize) + if status != fuse.OK { + tlog.Warn.Printf("zeroPad returned error %v", status) + return status + } + return fuse.OK } // Zero-pad the file of size plainSize to the next block boundary |