-static int nullf_write(BIO *h,char *buf,int num);
-static int nullf_read(BIO *h,char *buf,int size);
-static int nullf_puts(BIO *h,char *str);
-static int nullf_gets(BIO *h,char *str,int size);
-static long nullf_ctrl(BIO *h,int cmd,long arg1,char *arg2);
+static int nullf_write(BIO *h, const char *buf, int num);
+static int nullf_read(BIO *h, char *buf, int size);
+static int nullf_puts(BIO *h, const char *str);
+static int nullf_gets(BIO *h, char *str, int size);
+static long nullf_ctrl(BIO *h, int cmd, long arg1, void *arg2);