package mount import ( "io" "github.com/hanwen/go-fuse/v2/fuse" "github.com/seaweedfs/seaweedfs/weed/glog" ) /** * Read data * * Read should send exactly the number of bytes requested except * on EOF or error, otherwise the rest of the data will be * substituted with zeroes. An exception to this is when the file * has been opened in 'direct_io' mode, in which case the return * value of the read system call will reflect the return value of * this operation. * * fi->fh will contain the value set by the open method, or will * be undefined if the open method didn't set any value. * * Valid replies: * fuse_reply_buf * fuse_reply_iov * fuse_reply_data * fuse_reply_err * * @param req request handle * @param ino the inode number * @param size number of bytes to read * @param off offset to read from * @param fi file information */ func (wfs *WFS) Read(cancel <-chan struct{}, in *fuse.ReadIn, buff []byte) (fuse.ReadResult, fuse.Status) { fh := wfs.GetHandle(FileHandleId(in.Fh)) if fh == nil { return nil, fuse.ENOENT } fh.entryLock.Lock() defer fh.entryLock.Unlock() offset := int64(in.Offset) totalRead, err := readDataByFileHandle(buff, fh, offset) if err != nil { glog.Warningf("file handle read %s %d: %v", fh.FullPath(), totalRead, err) return nil, fuse.EIO } return fuse.ReadResultData(buff[:totalRead]), fuse.OK } func readDataByFileHandle(buff []byte, fhIn *FileHandle, offset int64) (int64, error) { // read data from source file size := len(buff) fhIn.lockForRead(offset, size) defer fhIn.unlockForRead(offset, size) n, err := fhIn.readFromChunks(buff, offset) if err == nil || err == io.EOF { maxStop := fhIn.readFromDirtyPages(buff, offset) n = max(maxStop-offset, n) } if err == io.EOF { err = nil } return n, err }