fd_open
extern fd_t *fd_open(char *, int, fd_t *);
if ((*fd = fd_open(procfile, O_RDONLY, *fd)) == NULL)
static int fd_open(dev_t *, int, int, cred_t *);
fd_open, /* open */
static int fd_open(dev_t *, int, int, cred_t *);
fd_open, /* open */