From: Karel Zak <kzak@redhat.com>
Date: Tue, 1 Oct 2019 10:51:04 +0000 (+0200)
Subject: libfdisk: (gpt) fix hybrid MBR detection, fix 'w'
X-Git-Tag: v2.35-rc1~183
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d84470388cb6b101a4ce1ecc079af9404bf052d;p=thirdparty%2Futil-linux.git

libfdisk: (gpt) fix hybrid MBR detection, fix 'w'

* current code overwrites hybrid MBR because EE partition
  is expected from fist sector, this is not true for hybrid MBR

* print "The partition table has been altered." message also for
  nested contexts

* remove "You have to sync the MBR manually" message

Addresses: https://github.com/karelzak/util-linux/issues/851
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/disk-utils/fdisk-menu.c b/disk-utils/fdisk-menu.c
index 3aba661fbe..71355f6848 100644
--- a/disk-utils/fdisk-menu.c
+++ b/disk-utils/fdisk-menu.c
@@ -595,9 +595,10 @@ static int generic_menu_cb(struct fdisk_context **cxt0,
 		rc = fdisk_write_disklabel(cxt);
 		if (rc)
 			err(EXIT_FAILURE, _("failed to write disklabel"));
+
+		fdisk_info(cxt, _("The partition table has been altered."));
 		if (fdisk_get_parent(cxt))
 			break; /* nested PT, don't leave */
-		fdisk_info(cxt, _("The partition table has been altered."));
 
 		if (device_is_used)
 			rc = fdisk_reread_changes(cxt, original_layout);
diff --git a/libfdisk/src/context.c b/libfdisk/src/context.c
index cbcadcf592..cb2164c2e6 100644
--- a/libfdisk/src/context.c
+++ b/libfdisk/src/context.c
@@ -537,12 +537,15 @@ static void reset_context(struct fdisk_context *cxt)
 
 	if (cxt->parent) {
 		/* the first sector may be independent on parent */
-		if (cxt->parent->firstsector != cxt->firstsector)
+		if (cxt->parent->firstsector != cxt->firstsector) {
+			DBG(CXT, ul_debugobj(cxt, "  firstsector independent on parent (freeing)"));
 			free(cxt->firstsector);
+		}
 	} else {
 		/* we close device only in primary context */
 		if (cxt->dev_fd > -1 && cxt->private_fd)
 			close(cxt->dev_fd);
+		DBG(CXT, ul_debugobj(cxt, "  freeing firstsector"));
 		free(cxt->firstsector);
 	}
 
diff --git a/libfdisk/src/gpt.c b/libfdisk/src/gpt.c
index f705791690..b5caab965d 100644
--- a/libfdisk/src/gpt.c
+++ b/libfdisk/src/gpt.c
@@ -870,17 +870,20 @@ static int valid_pmbr(struct fdisk_context *cxt)
 	if (ret != GPT_MBR_PROTECTIVE)
 		goto done;
 
-	/* LBA of the GPT partition header */
-	if (pmbr->partition_record[part].starting_lba !=
-	    cpu_to_le32(GPT_PRIMARY_PARTITION_TABLE_LBA))
-		goto done;
 
 	for (i = 0 ; i < 4; i++) {
 		if ((pmbr->partition_record[i].os_type != EFI_PMBR_OSTYPE) &&
-		    (pmbr->partition_record[i].os_type != 0x00))
+		    (pmbr->partition_record[i].os_type != 0x00)) {
 			ret = GPT_MBR_HYBRID;
+			goto done;
+		}
 	}
 
+	/* LBA of the GPT partition header */
+	if (pmbr->partition_record[part].starting_lba !=
+	    cpu_to_le32(GPT_PRIMARY_PARTITION_TABLE_LBA))
+		goto done;
+
 	/*
 	 * Protective MBRs take up the lesser of the whole disk
 	 * or 2 TiB (32bit LBA), ignoring the rest of the disk.
@@ -909,6 +912,9 @@ static int valid_pmbr(struct fdisk_context *cxt)
 		}
 	}
 done:
+	DBG(LABEL, ul_debug("PMBR type: %s",
+			ret == GPT_MBR_PROTECTIVE ? "protective" :
+			ret == GPT_MBR_HYBRID     ? "hybrid"     : "???" ));
 	return ret;
 }
 
@@ -1576,9 +1582,6 @@ static int gpt_probe_label(struct fdisk_context *cxt)
 	if (!mbr_type)
 		goto failed;
 
-	DBG(LABEL, ul_debug("found a %s MBR", mbr_type == GPT_MBR_PROTECTIVE ?
-			    "protective" : "hybrid"));
-
 	/* primary header */
 	gpt->pheader = gpt_read_header(cxt, GPT_PRIMARY_PARTITION_TABLE_LBA,
 				       &gpt->ents);
@@ -2028,6 +2031,7 @@ static int gpt_write_pmbr(struct fdisk_context *cxt)
 	assert(cxt);
 	assert(cxt->firstsector);
 
+	DBG(LABEL, ul_debug("(over)writing PMBR"));
 	pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
 
 	/* zero out the legacy partitions */
@@ -2116,8 +2120,7 @@ static int gpt_write_disklabel(struct fdisk_context *cxt)
 		goto err1;
 
 	if (mbr_type == GPT_MBR_HYBRID)
-		fdisk_warnx(cxt, _("The device contains hybrid MBR -- writing GPT only. "
-				   "You have to sync the MBR manually."));
+		fdisk_warnx(cxt, _("The device contains hybrid MBR -- writing GPT only."));
 	else if (gpt_write_pmbr(cxt) != 0)
 		goto err1;