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Diffstat (limited to 'internal/fusefrontend/file_holes.go')
-rw-r--r--internal/fusefrontend/file_holes.go92
1 files changed, 0 insertions, 92 deletions
diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go
deleted file mode 100644
index 2b7564e..0000000
--- a/internal/fusefrontend/file_holes.go
+++ /dev/null
@@ -1,92 +0,0 @@
-package fusefrontend
-
-// Helper functions for sparse files (files with holes)
-
-import (
- "runtime"
- "syscall"
-
- "github.com/hanwen/go-fuse/v2/fuse"
-
- "github.com/rfjakob/gocryptfs/internal/tlog"
-)
-
-// 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(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 contain a file hole in the ciphertext.
- status := f.zeroPad(plainSize)
- if status != fuse.OK {
- return status
- }
- return fuse.OK
-}
-
-// Zero-pad the file of size plainSize to the next block boundary. This is a no-op
-// if the file is already block-aligned.
-func (f *File) zeroPad(plainSize uint64) fuse.Status {
- lastBlockLen := plainSize % f.contentEnc.PlainBS()
- if lastBlockLen == 0 {
- // Already block-aligned
- return fuse.OK
- }
- missing := f.contentEnc.PlainBS() - lastBlockLen
- pad := make([]byte, missing)
- tlog.Debug.Printf("zeroPad: Writing %d bytes\n", missing)
- _, status := f.doWrite(pad, int64(plainSize))
- return status
-}
-
-// SeekData calls the lseek syscall with SEEK_DATA. It returns the offset of the
-// next data bytes, skipping over file holes.
-func (f *File) SeekData(oldOffset int64) (int64, error) {
- if runtime.GOOS != "linux" {
- // Does MacOS support something like this?
- return 0, syscall.EOPNOTSUPP
- }
- const SEEK_DATA = 3
-
- // Convert plaintext offset to ciphertext offset and round down to the
- // start of the current block. File holes smaller than a full block will
- // be ignored.
- blockNo := f.contentEnc.PlainOffToBlockNo(uint64(oldOffset))
- oldCipherOff := int64(f.contentEnc.BlockNoToCipherOff(blockNo))
-
- // Determine the next data offset. If the old offset points to (or beyond)
- // the end of the file, the Seek syscall fails with syscall.ENXIO.
- newCipherOff, err := syscall.Seek(f.intFd(), oldCipherOff, SEEK_DATA)
- if err != nil {
- return 0, err
- }
-
- // Convert ciphertext offset back to plaintext offset. At this point,
- // newCipherOff should always be >= contentenc.HeaderLen. Round down,
- // but ensure that the result is never smaller than the initial offset
- // (to avoid endless loops).
- blockNo = f.contentEnc.CipherOffToBlockNo(uint64(newCipherOff))
- newOffset := int64(f.contentEnc.BlockNoToPlainOff(blockNo))
- if newOffset < oldOffset {
- newOffset = oldOffset
- }
-
- return newOffset, nil
-}