#vulnerable code 
                                private void recover() {
        if (segments.isEmpty()) {
            return;
        }

        LOG.info("Recovering logs.");
        final List<Long> baseOffsets = new ArrayList<>(segments.navigableKeySet());
        final int offsetCount = baseOffsets.size();
        long offset = -1;
        for (int i = offsetCount - 2; i < offsetCount; i++) {
            if (i < 0) continue;

            final LogSegment segment = segments.get(baseOffsets.get(i));
            offset = segment.getBaseOffset();
            final LogSegmentValidator.ValidateResult result = segmentValidator.validate(segment);
            offset += result.getValidatedSize();
            if (result.getStatus() == LogSegmentValidator.ValidateStatus.COMPLETE) {
                segment.setWrotePosition(segment.getFileSize());
            } else {
                break;
            }
        }
        flushedOffset = offset;

        final long maxOffset = latestSegment().getBaseOffset() + latestSegment().getFileSize();
        final int relativeOffset = (int) (offset % fileSize);
        final LogSegment segment = locateSegment(offset);
        if (segment != null && maxOffset != offset) {
            segment.setWrotePosition(relativeOffset);
            LOG.info("recover wrote offset to {}:{}", segment, segment.getWrotePosition());
            // TODO(keli.wang): should delete crash file
        }
        LOG.info("Recover done.");
    } 
                            #location 25 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private void recover() {
        if (segments.isEmpty()) {
            return;
        }

        LOG.info("Recovering logs.");
        final List<Long> baseOffsets = new ArrayList<>(segments.navigableKeySet());
        final int offsetCount = baseOffsets.size();
        long offset = -1;
        for (int i = offsetCount - 2; i < offsetCount; i++) {
            if (i < 0) continue;

            final LogSegment segment = segments.get(baseOffsets.get(i));
            offset = segment.getBaseOffset();
            final LogSegmentValidator.ValidateResult result = segmentValidator.validate(segment);
            offset += result.getValidatedSize();
            if (result.getStatus() == LogSegmentValidator.ValidateStatus.COMPLETE) {
                segment.setWrotePosition(segment.getFileSize());
            } else {
                break;
            }
        }
        flushedOffset = offset;

        final LogSegment latestSegment = latestSegment();
        final long maxOffset = latestSegment.getBaseOffset() + latestSegment.getFileSize();
        final int relativeOffset = (int) (offset % fileSize);
        final LogSegment segment = locateSegment(offset);
        if (segment != null && maxOffset != offset) {
            segment.setWrotePosition(relativeOffset);
            LOG.info("recover wrote offset to {}:{}", segment, segment.getWrotePosition());
            if (segment.getBaseOffset() != latestSegment.getBaseOffset()) {
                LOG.info("will remove all segment after max wrote position. current base offset: {}, max base offset: {}",
                        segment.getBaseOffset(), latestSegment.getBaseOffset());
                deleteSegmentsAfterOffset(offset);
            }
        }
        LOG.info("Recover done.");
    }