+static int change_SO(bam_header_t *h, const char *so)
+{
+ char *p, *q, *beg = 0, *end = 0, *newtext;
+ if (h->l_text > 3) {
+ if (strncmp(h->text, "@HD", 3) == 0) {
+ if ((p = strchr(h->text, '\n')) == 0) return -1;
+ *p = '\0';
+ if ((q = strstr(h->text, "\tSO:")) != 0) {
+ *p = '\n'; // change back
+ if (strncmp(q + 4, so, p - q - 4) != 0) {
+ beg = q;
+ for (q += 4; *q != '\n' && *q != '\t'; ++q);
+ end = q;
+ } else return 0; // no need to change
+ } else beg = end = p, *p = '\n';
+ }
+ }
+ if (beg == 0) { // no @HD
+ h->l_text += strlen(so) + 15;
+ newtext = malloc(h->l_text + 1);
+ sprintf(newtext, "@HD\tVN:1.3\tSO:%s\n", so);
+ strcat(newtext, h->text);
+ } else { // has @HD but different or no SO
+ h->l_text = (beg - h->text) + (4 + strlen(so)) + (h->text + h->l_text - end);
+ newtext = malloc(h->l_text + 1);
+ strncpy(newtext, h->text, beg - h->text);
+ sprintf(newtext + (beg - h->text), "\tSO:%s", so);
+ strcat(newtext, end);
+ }
+ free(h->text);
+ h->text = newtext;
+ return 0;
+}
+