__fwriting
int __fwriting(FILE *);
PROTO_DEPRECATED(__fwriting);
assert(__fwriting(fp) != 0); /* writing is true immediately */
assert(__fwriting(fp) != 0); /* writing immediately */
assert(__fwriting(fp) != 0);
assert(__fwriting(fp) == 0); /* writing becomes false */
assert(__fwriting(fp) != 0); /* writing becomes true */
assert(__fwriting(fp) == 0); /* ungetc -> writing becomes false */