From: Karel Zak <kzak@redhat.com>
Date: Fri, 26 May 2017 11:11:37 +0000 (+0200)
Subject: wipefs: print all signature permutations
X-Git-Tag: v2.31-rc1~248
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92296e9ba2bf95259520fa7537ff8edc2aa9edbc;p=thirdparty%2Futil-linux.git

wipefs: print all signature permutations

The same FS/RAID/PT signature may be detected by more ways and on more
places on the device. The libblkid returns only the first detected
signature by default. This patch use blkid_probe_hide_range() to
re-scan device for all possible permutations of the same signature.

For example the default wipefs(8) output as well as --no-act output will
contains primary as well as backup GPT signature now.

Reported-by: Ruediger Meier <sweet_f_a@gmx.de>
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/misc-utils/wipefs.8 b/misc-utils/wipefs.8
index b7c7467feb..283c0b0e5a 100644
--- a/misc-utils/wipefs.8
+++ b/misc-utils/wipefs.8
@@ -16,9 +16,9 @@ can erase filesystem, raid or partition-table signatures (magic strings) from
 the specified
 .I device
 to make the signatures invisible for libblkid.
-
 .B wipefs
 does not erase the filesystem itself nor any other data from the device.
+
 When used without any options, \fBwipefs\fR lists all visible filesystems
 and the offsets of their basic signatures.
 
@@ -27,14 +27,10 @@ calls the BLKRRPART ioctl when it has erased a partition-table signature
 to inform the kernel about the change.
 
 Note that some filesystems and some partition tables store more magic strings on
-the device.  The
+the device (e.g. FAT, ZFS, GPT).  The
 .B wipefs
-command lists only the first offset where a magic string has been detected.  The device
-is not scanned for additional magic strings for the same filesystem.  It is possible
-that after a \fBwipefs -o \fIoffset\fR the same filesystem or partition
-table will still be visible because of another magic string on another offset. The
-option \fB\-\-no\-act\fR is also affected by this behavior and only the first
-magic string for the filesystem is reported.
+command (since v2.31) lists all the offset where a magic strings have been
+detected.
 
 When option \fB-a\fR is used, all magic strings that are visible for libblkid are
 erased. In this case the
diff --git a/misc-utils/wipefs.c b/misc-utils/wipefs.c
index 87abba39be..e17d6b4a0d 100644
--- a/misc-utils/wipefs.c
+++ b/misc-utils/wipefs.c
@@ -281,6 +281,10 @@ read_offsets(struct wipe_desc *wp, const char *devname)
 		wp = get_desc_for_probe(wp, pr);
 		if (!wp)
 			break;
+
+		/* hide last detected signature and scan again */
+		blkid_probe_hide_range(pr, wp->offset, wp->len);
+		blkid_probe_step_back(pr);
 	}
 
 	blkid_free_probe(pr);