fdisk: add --wipe-partitions=auto|never|default

The option allows to remove filesystes/RAIDs from newly created
partitions before the partition table is updated (and partition
device created).

The default is "auto" in this case wipe is enabled in interactive mode
only and user's confirmation (yes/no dialog) is required. Note that
keep filesystem signature on partition is pretty valid use-case, so we
don't erase anything by default.

Signed-off-by: Karel Zak <kzak@redhat.com>

4 files changed, 61 insertions, 2 deletions

diff --git a/disk-utils/fdisk-menu.c b/disk-utils/fdisk-menu.c
index becdb40e4..b099cc3c2 100644
--- a/disk-utils/fdisk-menu.c
+++ b/disk-utils/fdisk-menu.c
@@ -516,6 +516,37 @@ done:
 	return rc;
 }
 
+static int ask_for_wipe(struct fdisk_context *cxt, size_t partno)
+{
+	struct fdisk_partition *tmp = NULL;
+	char *fstype = NULL;
+	int rc, yes = 0;
+
+	rc = fdisk_get_partition(cxt, partno, &tmp);
+	if (rc)
+		goto done;
+
+	rc = fdisk_partition_to_string(tmp, cxt, FDISK_FIELD_FSTYPE, &fstype);
+	if (rc || fstype == NULL)
+		goto done;
+
+	fdisk_warnx(cxt, _("Partition #%zu contains a %s signature."), partno + 1, fstype);
+
+	if (pwipemode == WIPEMODE_AUTO && isatty(STDIN_FILENO))
+		fdisk_ask_yesno(cxt, _("Do you want to remove the signature?"), &yes);
+	else if (pwipemode == WIPEMODE_ALWAYS)
+		yes = 1;
+
+	if (yes) {
+		fdisk_info(cxt, _("The signature will be removed by a write command."));
+		rc = fdisk_wipe_partition(cxt, partno, TRUE);
+	}
+done:
+	fdisk_unref_partition(tmp);
+	free(fstype);
+	return rc;
+}
+
 /*
  * Basic fdisk actions
  */
@@ -610,8 +641,13 @@ static int generic_menu_cb(struct fdisk_context **cxt0,
 		list_partition_types(cxt);
 		break;
 	case 'n':
-		rc = fdisk_add_partition(cxt, NULL, NULL);
+	{
+		size_t partno;
+		rc = fdisk_add_partition(cxt, NULL, &partno);
+		if (!rc)
+			rc = ask_for_wipe(cxt, partno);
 		break;
+	}
 	case 't':
 		change_partition_type(cxt);
 		break;
diff --git a/disk-utils/fdisk.8 b/disk-utils/fdisk.8
index 41069dd7a..5d644d8d6 100644
--- a/disk-utils/fdisk.8
+++ b/disk-utils/fdisk.8
@@ -130,6 +130,18 @@ before a new partition table is created.  See also
 command.
 
 .TP
+\fB\-W\fR, \fB\-\-wipe-partition\fR \fIwhen\fR
+Wipe filesystem, RAID and partition-table signatures from a newly created
+partitions, in order to avoid possible collisions.  The argument \fIwhen\fR can
+be \fBauto\fR, \fBnever\fR or \fBalways\fR.  When this option is not given, the
+default is \fBauto\fR, in which case signatures are wiped only when in
+interactive mode and after confirmation by user.  In all cases detected
+signatures are reported by warning messages before a new partition is
+created.  See also
+.BR wipefs (8)
+command.
+
+.TP
 \fB\-V\fR, \fB\-\-version\fR
 Display version information and exit.
 
diff --git a/disk-utils/fdisk.c b/disk-utils/fdisk.c
index 73d82eb4c..1f1f9ba6b 100644
--- a/disk-utils/fdisk.c
+++ b/disk-utils/fdisk.c
@@ -49,6 +49,8 @@
 # include <linux/blkpg.h>
 #endif
 
+int pwipemode = WIPEMODE_AUTO;
+
 /*
  * fdisk debug stuff (see fdisk.h and include/debug.h)
  */
@@ -741,6 +743,7 @@ static void __attribute__ ((__noreturn__)) usage(FILE *out)
 	fputs(_(" -s, --getsz                   display device size in 512-byte sectors [DEPRECATED]\n"), out);
 	fputs(_("     --bytes                   print SIZE in bytes rather than in human readable format\n"), out);
 	fputs(_(" -w, --wipe <mode>             wipe signatures (auto, always or never)\n"), out);
+	fputs(_(" -W, --wipe-partitions <mode>  wipe signatures from new partitions (auto, always or never)\n"), out);
 
 	fputs(USAGE_SEPARATOR, out);
 	fputs(_(" -C, --cylinders <number>      specify the number of cylinders\n"), out);
@@ -791,6 +794,7 @@ int main(int argc, char **argv)
 		{ "output",         no_argument,       NULL, 'o' },
 		{ "protect-boot",   no_argument,       NULL, 'B' },
 		{ "wipe",           required_argument, NULL, 'w' },
+		{ "wipe-partitions",required_argument, NULL, 'W' },
 		{ NULL, 0, NULL, 0 }
 	};
 
@@ -809,7 +813,7 @@ int main(int argc, char **argv)
 
 	fdisk_set_ask(cxt, ask_callback, NULL);
 
-	while ((c = getopt_long(argc, argv, "b:Bc::C:hH:lL::o:sS:t:u::vVw:",
+	while ((c = getopt_long(argc, argv, "b:Bc::C:hH:lL::o:sS:t:u::vVw:W:",
 				longopts, NULL)) != -1) {
 		switch (c) {
 		case 'b':
@@ -905,6 +909,11 @@ int main(int argc, char **argv)
 			if (wipemode < 0)
 				errx(EXIT_FAILURE, _("unsupported wipe mode"));
 			break;
+		case 'W':
+			pwipemode = wipemode_from_string(optarg);
+			if (pwipemode < 0)
+				errx(EXIT_FAILURE, _("unsupported wipe mode"));
+			break;
 		case 'h':
 			usage(stdout);
 		case OPT_BYTES:
diff --git a/disk-utils/fdisk.h b/disk-utils/fdisk.h
index f66404d04..7a7fb85d3 100644
--- a/disk-utils/fdisk.h
+++ b/disk-utils/fdisk.h
@@ -24,6 +24,8 @@
 #define FDISKPROG_DEBUG_ASK	(1 << 5)
 #define FDISKPROG_DEBUG_ALL	0xFFFF
 
+extern int pwipemode;
+
 UL_DEBUG_DECLARE_MASK(fdisk);
 #define DBG(m, x)       __UL_DBG(fdisk, FDISKPROG_DEBUG_, m, x)
 #define ON_DBG(m, x)    __UL_DBG_CALL(fdisk, FDISKPROG_DEBUG_, m, x)