- if (iter->finished) return -1;
- if (iter->from_first) {
- int ret = bam_read1(fp, b);
- if (ret < 0) iter->finished = 1;
+ int ret;
+ if (iter && iter->finished) return -1;
+ if (iter == 0 || iter->from_first) {
+ ret = bam_read1(fp, b);
+ if (ret < 0 && iter) iter->finished = 1;