| 134 | } |
| 135 | |
| 136 | func NewIncrementalPageReader(file io.ReadSeekCloser, eof, offset int64) (io.ReadCloser, error) { |
| 137 | if eof <= offset { |
| 138 | return nil, fmt.Errorf("file eof %d is less or equal than offset %d", eof, offset) |
| 139 | } |
| 140 | var headerBuffer bytes.Buffer |
| 141 | headerBuffer.Write(IncrementFileHeader) |
| 142 | headerBuffer.Write(utility.ToBytes(uint64(eof))) |
| 143 | headerBuffer.Write(utility.ToBytes(uint64(offset))) |
| 144 | |
| 145 | if _, err := file.Seek(offset, io.SeekStart); err != nil { |
| 146 | utility.LoggedClose(file, "") |
| 147 | return nil, err |
| 148 | } |
| 149 | |
| 150 | return &ioextensions.ReadCascadeCloser{ |
| 151 | Reader: &io.LimitedReader{ |
| 152 | R: io.MultiReader(&headerBuffer, limiters.NewDiskLimitReader(file)), |
| 153 | N: int64(headerBuffer.Len()) + eof - offset, |
| 154 | }, |
| 155 | Closer: file, |
| 156 | }, nil |
| 157 | } |