package mount import ( "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.Lock() defer fh.Unlock() fh.entryLock.Lock() defer fh.entryLock.Unlock() fileSize := int64(filer.FileSize(fh.entry)) 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.Chunks, 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 }