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-rw-r--r--internal/fusefrontend/file_holes.go15
1 files changed, 15 insertions, 0 deletions
diff --git a/internal/fusefrontend/file_holes.go b/internal/fusefrontend/file_holes.go
index 2b95c5c..04a00ec 100644
--- a/internal/fusefrontend/file_holes.go
+++ b/internal/fusefrontend/file_holes.go
@@ -3,6 +3,9 @@ package fusefrontend
// Helper functions for sparse files (files with holes)
import (
+ "runtime"
+ "syscall"
+
"github.com/hanwen/go-fuse/fuse"
"github.com/rfjakob/gocryptfs/internal/tlog"
@@ -53,3 +56,15 @@ func (f *File) zeroPad(plainSize uint64) fuse.Status {
_, 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
+ fd := f.intFd()
+ return syscall.Seek(fd, oldOffset, SEEK_DATA)
+}