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package mount
import ( "context" "syscall"
"github.com/hanwen/go-fuse/v2/fuse"
"github.com/seaweedfs/seaweedfs/weed/filer" "github.com/seaweedfs/seaweedfs/weed/glog" )
// These are non-POSIX extensions
const ( SEEK_DATA uint32 = 3 // seek to next data after the offset
SEEK_HOLE uint32 = 4 // seek to next hole after the offset
ENXIO = fuse.Status(syscall.ENXIO) )
// Lseek finds next data or hole segments after the specified offset
// See https://man7.org/linux/man-pages/man2/lseek.2.html
func (wfs *WFS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekOut) fuse.Status { // not a documented feature
if in.Padding != 0 { return fuse.EINVAL }
if in.Whence != SEEK_DATA && in.Whence != SEEK_HOLE { return fuse.EINVAL }
// file must exist
fh := wfs.GetHandle(FileHandleId(in.Fh)) if fh == nil { return fuse.EBADF }
// lock the file until the proper offset was calculated
fh.orderedMutex.Acquire(context.Background(), 1) defer fh.orderedMutex.Release(1) //fh.entryLock.Lock()
//defer fh.entryLock.Unlock()
fileSize := int64(filer.FileSize(fh.GetEntry())) offset := max(int64(in.Offset), 0)
glog.V(4).Infof( "Lseek %s fh %d in [%d,%d], whence %d", fh.FullPath(), fh.fh, offset, fileSize, in.Whence, )
// can neither seek beyond file nor seek to a hole at the end of the file with SEEK_DATA
if offset > fileSize { return ENXIO } else if in.Whence == SEEK_DATA && offset == fileSize { return ENXIO }
// refresh view cache if necessary
if fh.entryViewCache == nil { var err error fh.entryViewCache, err = filer.NonOverlappingVisibleIntervals(fh.wfs.LookupFn(), fh.entry.GetChunks(), 0, fileSize) if err != nil { return fuse.EIO } }
// search chunks for the offset
found, offset := searchChunks(fh, offset, fileSize, in.Whence) if found { out.Offset = uint64(offset) return fuse.OK }
// in case we found no exact matches, we return the recommended fallbacks, that is:
// original offset for SEEK_DATA or end of file for an implicit hole
if in.Whence == SEEK_DATA { out.Offset = in.Offset } else { out.Offset = uint64(fileSize) }
return fuse.OK }
// searchChunks goes through all chunks to find the correct offset
func searchChunks(fh *FileHandle, offset, fileSize int64, whence uint32) (found bool, out int64) { chunkViews := filer.ViewFromVisibleIntervals(fh.entryViewCache, offset, fileSize)
for _, chunkView := range chunkViews { if offset < chunkView.LogicOffset { if whence == SEEK_HOLE { out = offset } else { out = chunkView.LogicOffset }
return true, out }
if offset >= chunkView.LogicOffset && offset < chunkView.Offset+int64(chunkView.Size) && whence == SEEK_DATA { out = offset
return true, out }
offset += int64(chunkView.Size) }
return }
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