Add an -f option (for force) to the create command. The -f option

allows the user to force the creation of a GPT even when there's a
MBR on the device. The MBR is simply wiped and any partitions
described by it are lost. Without the -f option one cannot create
a GPT when there's a MBR.

2 files changed, 25 insertions, 6 deletions

diff --git a/sbin/gpt/create.c b/sbin/gpt/create.c
index 6591b93..54084c2 100644
--- a/sbin/gpt/create.c
+++ b/sbin/gpt/create.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 #include "map.h"
 #include "gpt.h"
 
+static int force;
 static int primary_only;
 
 static void
@@ -46,7 +47,7 @@ usage_create(void)
 {
 
 	fprintf(stderr,
-	    "usage: %s [-p] device ...\n", getprogname());
+	    "usage: %s [-fp] device ...\n", getprogname());
 	exit(1);
 }
 
@@ -70,9 +71,15 @@ create(int fd)
 		warnx("%s: error: device already contains a GPT", device_name);
 		return;
 	}
-	if (map_find(MAP_TYPE_MBR) != NULL) {
-		warnx("%s: error: device contains a MBR", device_name);
-		return;
+	map = map_find(MAP_TYPE_MBR);
+	if (map != NULL) {
+		if (!force) {
+			warnx("%s: error: device contains a MBR", device_name);
+			return;
+		}
+
+		/* Nuke the MBR in our internal map. */
+		map->map_type = MAP_TYPE_UNUSED;
 	}
 
 	/*
@@ -206,8 +213,11 @@ cmd_create(int argc, char *argv[])
 {
 	int ch, fd;
 
-	while ((ch = getopt(argc, argv, "p")) != -1) {
+	while ((ch = getopt(argc, argv, "fp")) != -1) {
 		switch(ch) {
+		case 'f':
+			force = 1;
+			break;
 		case 'p':
 			primary_only = 1;
 			break;
diff --git a/sbin/gpt/gpt.8 b/sbin/gpt/gpt.8
index a96d694..8909812 100644
--- a/sbin/gpt/gpt.8
+++ b/sbin/gpt/gpt.8
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 30, 2004
+.Dd November 12, 2004
 .Os
 .Dt GPT 8
 .Sh NAME
@@ -138,12 +138,21 @@ as aliases for the most commonly used partition types.
 .It Xo
 .Nm
 .Ic create
+.Op Fl f
 .Op Fl p
 .Ar device ...
 .Xc
 The
 .Ic create
 command allows the user to create a new (empty) GPT.
+By default one can not create a GPT when the device contains a MBR,
+however this can be overridden with the
+.Fl f
+option.
+If the
+.Fl f
+option is specified, an existing MBR is destroyed and any partitions
+described by the MBR are lost.
 .Pp
 The
 .Fl p