diff options
| -rw-r--r-- | internal/fusefrontend/file.go | 2 | ||||
| -rw-r--r-- | internal/fusefrontend/file_holes.go | 10 |
2 files changed, 9 insertions, 3 deletions
diff --git a/internal/fusefrontend/file.go b/internal/fusefrontend/file.go index 35c898d..9fb9f7e 100644 --- a/internal/fusefrontend/file.go +++ b/internal/fusefrontend/file.go @@ -306,7 +306,7 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) { return 0, fuse.ToStatus(err) } plainSize := f.contentEnc.CipherSizeToPlainSize(uint64(fi.Size())) - if f.createsHole(plainSize, off) { + if f.createsCiphertextHole(plainSize, off) { status := f.zeroPad(plainSize) if status != fuse.OK { tlog.Warn.Printf("zeroPad returned error %v", status) diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go index 34f702f..ff626d1 100644 --- a/internal/fusefrontend/file_holes.go +++ b/internal/fusefrontend/file_holes.go @@ -8,10 +8,16 @@ import ( "github.com/rfjakob/gocryptfs/internal/tlog" ) -// Will a write to offset "off" create a file hole? -func (f *file) createsHole(plainSize uint64, off int64) bool { +// Will a write to plaintext offset "off" create a file hole in the ciphertext? +func (f *file) createsCiphertextHole(plainSize uint64, off int64) bool { + // 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 } |