2 files changed, 58 insertions, 15 deletions

diff --git a/sbin/sysctl/sysctl.8 b/sbin/sysctl/sysctl.8
index 9912b06fe256..18b405f95aa2 100644
--- a/sbin/sysctl/sysctl.8
+++ b/sbin/sysctl/sysctl.8
@@ -32,7 +32,7 @@
 .\"	From: @(#)sysctl.8	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd May 28, 2001
+.Dd March 10, 2002
 .Dt SYSCTL 8
 .Os
 .Sh NAME
@@ -118,7 +118,9 @@ few bytes.
 .Pp
 The information available from
 .Nm
-consists of integers, strings, and opaques.
+consists of integers, strings, devices
+.Pq Vt dev_t ,
+and opaque types.
 .Nm Sysctl
 only knows about a couple of opaque types, and will resort to hexdumps
 for the rest.
@@ -134,6 +136,17 @@ For a detailed description of these variable see
 .Pp
 The changeable column indicates whether a process with appropriate
 privilege can change the value.
+String, integer, and devices values can be set using
+.Nm .
+For device values,
+.Ar value
+can be specified as a character device special file name.
+Special values
+.Ar off
+and
+.Ar none
+denote
+.Dq no device .
 .Bl -column net.inet.ip.forwardingxxxxxx integerxxx
 .It Sy "Name	Type	Changeable
 .It "kern.ostype	string	no
@@ -162,6 +175,7 @@ privilege can change the value.
 .It "kern.osreldate	string	no
 .It "kern.bootfile	string	yes
 .It "kern.corefile	string	yes
+.It "kern.dumpdev	dev_t	yes
 .It "kern.logsigexit	integer	yes
 .It "vm.loadavg	struct	no
 .It "hw.machine	string	no
@@ -208,6 +222,14 @@ per uid to 1000, one would use the following request:
 .Pp
 .Dl "sysctl kern.maxprocperuid=1000"
 .Pp
+The device used for crash dumps can be specified using:
+.Pp
+.Dl "sysctl kern.dumpdev=/dev/somedev"
+.Pp
+which is equivalent to
+.Pp
+.Dl "dumpon /dev/somedev"
+.Pp
 Information about the system clock rate may be obtained with:
 .Pp
 .Dl "sysctl kern.clockrate"
diff --git a/sbin/sysctl/sysctl.c b/sbin/sysctl/sysctl.c
index 2d8649827523..d19ab92fced2 100644
--- a/sbin/sysctl/sysctl.c
+++ b/sbin/sysctl/sysctl.c
@@ -53,6 +53,7 @@ static const char rcsid[] =
 #include <sys/stat.h>
 #include <sys/sysctl.h>
 #include <sys/resource.h>
+#include <sys/param.h>
 
 #include <ctype.h>
 #include <err.h>
@@ -70,6 +71,8 @@ static int	show_var(int *, int);
 static int	sysctl_all (int *oid, int len);
 static int	name2oid(char *, int *);
 
+static void	set_T_dev_t (char *, void **, int *);
+
 static void
 usage(void)
 {
@@ -157,7 +160,7 @@ parse(char *string)
 	size_t newsize = 0;
 	quad_t quadval;
 	int mib[CTL_MAXNAME];
-	char *cp, *bufp, buf[BUFSIZ];
+	char *cp, *bufp, buf[BUFSIZ], fmt[BUFSIZ];
 	u_int kind;
 
 	bufp = buf;
@@ -175,7 +178,7 @@ parse(char *string)
 	if (len < 0) 
 		errx(1, "unknown oid '%s'", bufp);
 
-	if (oidfmt(mib, len, 0, &kind))
+	if (oidfmt(mib, len, fmt, &kind))
 		err(1, "couldn't find format of oid '%s'", bufp);
 
 	if (newval == NULL) {
@@ -217,11 +220,16 @@ parse(char *string)
 			case CTLTYPE_STRING:
 				break;
 			case CTLTYPE_QUAD:
-				break;
 				sscanf(newval, "%qd", &quadval);
 				newval = &quadval;
 				newsize = sizeof(quadval);
 				break;
+			case CTLTYPE_OPAQUE:
+				if (strcmp(fmt, "T,dev_t") == 0) {
+					set_T_dev_t ((char*)newval, &newval, &newsize);
+					break;
+				}
+				/* FALLTHROUGH */
 			default:
 				errx(1, "oid '%s' is type %d,"
 					" cannot set that", bufp,
@@ -323,6 +331,27 @@ T_dev_t(int l2, void *p)
 	return (0);
 }
 
+static void
+set_T_dev_t (char *path, void **val, int *size)
+{
+	static struct stat statb;
+
+	if (strcmp(path, "none") && strcmp(path, "off")) {
+		int rc = stat (path, &statb);
+		if (rc) {
+			err(1, "cannot stat %s", path);
+		}
+
+		if (!S_ISCHR(statb.st_mode)) {
+			errx(1, "must specify a device special file.");
+		}
+	} else {
+		statb.st_rdev = NODEV;
+	}
+	*val = (char*) &statb.st_rdev;
+	*size = sizeof statb.st_rdev;
+}
+
 /*
  * These functions uses a presently undocumented interface to the kernel
  * to walk the tree and get the type so it can print the value.
@@ -478,16 +507,8 @@ show_var(int *oid, int nlen)
 		return (0);
 	}
 
-	qoid[1] = 4;
-	j = sizeof(buf);
-	i = sysctl(qoid, nlen + 2, buf, &j, 0, 0);
-	if (i || !j)
-		err(1, "sysctl fmt %d %d %d", i, j, errno);
-
-	kind = *(u_int *)buf;
-
-	fmt = (char *)(buf + sizeof(u_int));
-
+	fmt = buf;
+	oidfmt(oid, nlen, fmt, &kind);
 	p = val;
 	switch (*fmt) {
 	case 'A':