Finally implement the "auto" disktype. It attempts to get all the

required information from the driver, and produce a virgin disklabel
for it.  The latter might be further edited with `disklabel -e' to
satisfy the user's need.

The magic sequence is:

	disklabel -r -w sdX auto
	disklabel -e sdX

2 files changed, 68 insertions, 1 deletions

diff --git a/sbin/bsdlabel/bsdlabel.8 b/sbin/bsdlabel/bsdlabel.8
index bf14e0f..1cc33ab 100644
--- a/sbin/bsdlabel/bsdlabel.8
+++ b/sbin/bsdlabel/bsdlabel.8
@@ -161,6 +161,21 @@ If the disk does not already have a label, the
 flag must be used.
 In either case, the kernel's in-core label is replaced.
 .Pp
+For a virgin disk that is not known to
+.Xr disktab 5 ,
+.Ar disktype
+can be specified as
+.Dq auto .
+In this case, the driver is requested to produce a virgin label for the
+disk.  This might or might not be successful, depending on whether the
+driver for the disk is able to get the required data without reading
+anything from the disk at all.  It will likely succeed for all SCSI
+disks, most IDE disks, and vnode devices.  Writing a label to the
+disk is the only supported operation, and the
+.Ar disk
+itself must be provided as the canonical name, i.e. not as a full
+path name.
+.Pp
 An existing disk label may be edited by using the
 .Fl e
 flag.
@@ -286,6 +301,12 @@ Read the on-disk label for sd0, edit it and reinstall in-core as well
 as on-disk.
 Existing bootstrap code is unaffected.
 .Pp
+.Dl disklabel -r -w sd0 auto
+.Pp
+Try to auto-detect the required information from sd0, and write a new
+label to the disk.  Use another disklabel -e command to edit the
+partitioning and file system information.
+.Pp
 .Dl disklabel -R sd0 mylabel
 .Pp
 Restore the on-disk and in-core label for sd0 from information in
diff --git a/sbin/bsdlabel/bsdlabel.c b/sbin/bsdlabel/bsdlabel.c
index d3337c1..cf93fc4 100644
--- a/sbin/bsdlabel/bsdlabel.c
+++ b/sbin/bsdlabel/bsdlabel.c
@@ -110,6 +110,7 @@ void	Warning		(char *, ...);
 void	Perror		__P((char *));
 void	usage		__P((void));
 extern	u_short dkcksum __P((struct disklabel *));
+struct disklabel * getvirginlabel __P((void));
 
 #define	DEFEDITOR	_PATH_VI
 #define	streq(a,b)	(strcmp(a,b) == 0)
@@ -336,7 +337,10 @@ makelabel(type, name, lp)
 	register struct disklabel *lp;
 {
 	register struct disklabel *dp;
-	char *strcpy();
+
+	if (strcmp(type, "auto") == 0)
+		dp = getvirginlabel();
+	else
 		dp = getdiskbyname(type);
 	if (dp == NULL) {
 		fprintf(stderr, "%s: unknown disk type\n", type);
@@ -1280,6 +1284,48 @@ checklabel(lp)
 }
 
 /*
+ * When operating on a "virgin" disk, try getting an initial label
+ * from the associated device driver.  This might work for all device
+ * drivers that are able to fetch some initial device parameters
+ * without even having access to a (BSD) disklabel, like SCSI disks,
+ * most IDE drives, or vn devices.
+ *
+ * The device name must be given in its "canonical" form.
+ */
+struct disklabel *
+getvirginlabel(void)
+{
+	static struct disklabel lab;
+	char namebuf[BBSIZE];
+	int f;
+
+	if (dkname[0] == '/') {
+		fprintf(stderr,
+		"\"auto\" requires the usage of a canonical disk name.\n");
+		return 0;
+	}
+	(void)snprintf(namebuf, BBSIZE, "%sr%s", _PATH_DEV, dkname);
+	if ((f = open(namebuf, O_RDONLY, 0)) == -1) {
+		Perror("open()");
+		return 0;
+	}
+	if (ioctl(f, DIOCGDINFO, &lab) < 0) {
+		Perror("ioctl DIOCGDINFO");
+		close(f);
+		return 0;
+	}
+	close(f);
+	/* insert reasonable defaults where necessary */
+	if (lab.d_npartitions < 8) lab.d_npartitions = 8;
+	if (lab.d_bbsize == 0) lab.d_bbsize = BBSIZE;
+	if (lab.d_sbsize == 0) lab.d_sbsize = SBSIZE;
+	if (lab.d_rpm == 0) lab.d_rpm = 3600;
+	if (lab.d_interleave == 0) lab.d_interleave = 1;
+	return &lab;
+}
+
+
+/*
  * If we are installing a boot program that doesn't fit in d_bbsize
  * we need to mark those partitions that the boot overflows into.
  * This allows newfs to prevent creation of a filesystem where it might