Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!hc!beta!cmcl2!brl-adm!adm!chris@mimsy.umd.edu
From: chris@mimsy.umd.edu (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re:  Reading VAX SID register on ultrix or 4.3bsd
Message-ID: <13092@brl-adm.ARPA>
Date: 23 Apr 88 05:32:44 GMT
Sender: news@brl-adm.ARPA
Lines: 45

Make nlist a syscall?  Not quite...!

The following might, however, be interesting: have a privileged program
dig out those `interesting numbers'---all the post-boot static ones,
anyway---and put them in a file, storing them at offsets derived from
the offset in /vmunix (or local equivalent).

Look Ma (Ma Bell? :-) ), a getdtablesize() C library function!:

int
read_saved_kernel_int(name)
	char *name;
{
	struct nlist nl[2];
	int fd, rv;

	nl[0].n_name = name;
	nl[1].n_name = NULL;
	if (nlist("/vmunix", nl))	/* something is wrong */
		return (-1);
	if ((fd = open("/etc/kdata", 0)) < 0)
		return (-1);
	(void) lseek(fd, (off_t)nl[0].n_value - (off_t)KERNBASE, L_SET);
	if (read(fd, (char *)&rv, sizeof(rv)) != sizeof(rv))
		rv = -1;
	(void) close(fd);
	return (rv);
}

int
getdtablesize()
{

	return (_read_saved_kernel_int("_dtablesize"));
}

int
getcputype()
{

	return (_read_saved_kernel_int("_cpu"));
}

/* ceteraque :-) */

Now all you have to do is write /etc/savekdata.