zopen
fpkern = zopen(buf, "w");
fp = zopen(buf, "w");
extern FILE *zopen(const char *, const char *);
FILE *zopen(const char *fname, const char *mode);
if ((ofp = zopen(out, "w", bits)) == NULL) {
if ((ifp = zopen(in, "r", bits)) == NULL) {
FILE *zopen(const char *, const char *, int);