This patch enables creating a new, empty, GPT disklabel from either
an empty disk or one that already has a disklabel. For this
purpose, a 'g' option is added to the main menu and is visible to all
labels. Here's an example for a scsi_debug device (/dev/sdb):
...
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x20a614c8.
3696: fdisk: CONTEXT: zeroize in-memory first sector buffer
Command (m for help): g
3696: fdisk: LABEL: changing to gpt label
3696: fdisk: CONTEXT: zeroize in-memory first sector buffer
3696: fdisk: LABEL: created new empty GPT disklabel (GUID: D4EA0706-F011-46DC-B7DE-6A72C7090AF8)
Command (m for help): w
The partition table has been altered!
...
Signed-off-by: Davidlohr Bueso <dave@xxxxxxx>
---
fdisks/fdisk.c | 4 ++
fdisks/gpt.c | 202 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 200 insertions(+), 6 deletions(-)
diff --git a/fdisks/fdisk.c b/fdisks/fdisk.c
index e271ea1..a3ac087 100644
--- a/fdisks/fdisk.c
+++ b/fdisks/fdisk.c
@@ -90,6 +90,7 @@ static const struct menulist_descr menulist[] = {
{'e', N_("edit drive data"), {OSF_LABEL, 0}},
{'f', N_("fix partition order"), {0, DOS_LABEL}},
{'g', N_("create an IRIX (SGI) partition table"), {0, ANY_LABEL}},
+ {'g', N_("create a new empty GPT partition table"), {ANY_LABEL, 0}},
{'h', N_("change number of heads"), {0, DOS_LABEL | SUN_LABEL}},
{'i', N_("change interleave factor"), {0, SUN_LABEL}},
{'i', N_("change the disk identifier"), {0, DOS_LABEL}},
@@ -1694,6 +1695,9 @@ static void command_prompt(struct fdisk_context *cxt)
case 'd':
delete_partition(cxt, get_existing_partition(cxt, 1, partitions));
break;
+ case 'g':
+ fdisk_create_disklabel(cxt, "gpt");
+ break;
case 'i':
if (disklabel == SGI_LABEL)
create_sgiinfo(cxt);
diff --git a/fdisks/gpt.c b/fdisks/gpt.c
index 48397f3..843dc44 100644
--- a/fdisks/gpt.c
+++ b/fdisks/gpt.c
@@ -19,7 +19,6 @@
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
- *
*/
#include <stdio.h>
@@ -59,7 +58,8 @@
#define EFI_PMBR_OSTYPE 0xEE
#define MSDOS_MBR_SIGNATURE 0xAA55
-#define GPT_PART_NAME_LEN 72 / sizeof(uint16_t)
+#define GPT_PART_NAME_LEN 72 / sizeof(uint16_t)
+#define GPT_NPARTITIONS 128
/* Globally unique identifier */
struct gpt_guid {
@@ -96,8 +96,8 @@ struct gpt_attr {
/* The GPT Partition entry array contains an array of GPT entries. */
struct gpt_entry {
- struct gpt_guid partition_type_guid; /* purpose and type of the partition */
- struct gpt_guid unique_partition_guid;
+ struct gpt_guid partition_type_guid; /* purpose and type of the partition */
+ struct gpt_guid unique_partition_guid;
uint64_t lba_start;
uint64_t lba_end;
struct gpt_attr attr;
@@ -115,7 +115,7 @@ struct gpt_header {
uint64_t alternative_lba; /* backup GPT header */
uint64_t first_usable_lba; /* first usable logical block for partitions */
uint64_t last_usable_lba; /* last usable logical block for partitions */
- struct gpt_guid disk_guid; /* unique disk identifier */
+ struct gpt_guid disk_guid; /* unique disk identifier */
uint64_t partition_entry_lba; /* stat LBA of the partition entry array */
uint32_t npartition_entries; /* total partition entries - normally 128 */
uint32_t sizeof_partition_entry; /* bytes for each GUID pt */
@@ -298,6 +298,125 @@ static inline int partition_unused(struct gpt_entry e)
}
/*
+ * Builds a clean new valid protective MBR - will wipe out any existing data.
+ * Returns 0 on success, otherwise < 0 on error.
+ */
+static int gpt_mknew_pmbr(struct fdisk_context *cxt)
+{
+ struct gpt_legacy_mbr *pmbr = NULL;
+
+ if (!cxt || !cxt->firstsector)
+ return -ENOSYS;
+
+ fdisk_zeroize_firstsector(cxt);
+
+ pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
+
+ pmbr->signature = cpu_to_le16(MSDOS_MBR_SIGNATURE);
+ pmbr->partition_record[0].os_type = EFI_PMBR_OSTYPE;
+ pmbr->partition_record[0].start_sector = 1;
+ pmbr->partition_record[0].end_head = 0xFE;
+ pmbr->partition_record[0].end_sector = 0xFF;
+ pmbr->partition_record[0].end_track = 0xFF;
+ pmbr->partition_record[0].starting_lba = cpu_to_le32(1);
+ pmbr->partition_record[0].size_in_lba =
+ cpu_to_le32(min((uint32_t) cxt->total_sectors - 1, 0xFFFFFFFF));
+
+ return 0;
+}
+
+/* some universal differences between the headers */
+static void gpt_mknew_header_common(struct fdisk_context *cxt,
+ struct gpt_header *header, uint64_t lba)
+{
+ if (!cxt || !header)
+ return;
+
+ header->my_lba = cpu_to_le64(lba);
+
+ if (lba == GPT_PRIMARY_PARTITION_TABLE_LBA) { /* primary */
+ header->alternative_lba = cpu_to_le64(cxt->total_sectors - 1);
+ header->partition_entry_lba = cpu_to_le64(2);
+ } else { /* backup */
+ uint64_t esz = le32_to_cpu(header->npartition_entries) * sizeof(struct gpt_entry);
+ uint64_t esects = (esz + cxt->sector_size - 1) / cxt->sector_size;
+
+ header->alternative_lba = cpu_to_le64(GPT_PRIMARY_PARTITION_TABLE_LBA);
+ header->partition_entry_lba = cpu_to_le64(cxt->total_sectors - 1 - esects);
+ }
+}
+
+/*
+ * Builds a new GPT header (at sector lba) from a backup header2.
+ * If building a primary header, then backup is the secondary, and vice versa.
+ *
+ * Always pass a new (zeroized) header to build upon as we don't
+ * explicitly zero-set some values such as CRCs and reserved.
+ *
+ * Returns 0 on success, otherwise < 0 on error.
+ */
+static int gpt_mknew_header_from_bkp(struct fdisk_context *cxt,
+ struct gpt_header *header,
+ uint64_t lba,
+ struct gpt_header *header2)
+{
+ if (!cxt || !header || !header2)
+ return -ENOSYS;
+
+ header->signature = header2->signature;
+ header->revision = header2->revision;
+ header->size = header2->size;
+ header->npartition_entries = header2->npartition_entries;
+ header->sizeof_partition_entry = header2->sizeof_partition_entry;
+ header->first_usable_lba = header2->first_usable_lba;
+ header->last_usable_lba = header2->last_usable_lba;
+
+ memcpy(&header->disk_guid,
+ &header2->disk_guid, sizeof(header2->disk_guid));
+ gpt_mknew_header_common(cxt, header, lba);
+
+ return 0;
+}
+
+/*
+ * Builds a clean new GPT header (currently under revision 1.0).
+ *
+ * Always pass a new (zeroized) header to build upon as we don't
+ * explicitly zero-set some values such as CRCs and reserved.
+ *
+ * Returns 0 on success, otherwise < 0 on error.
+ */
+static int gpt_mknew_header(struct fdisk_context *cxt,
+ struct gpt_header *header, uint64_t lba)
+{
+ uint64_t esz = 0;
+
+ if (!cxt || !header)
+ return -ENOSYS;
+
+ esz = sizeof(struct gpt_entry) * GPT_NPARTITIONS / cxt->sector_size;
+
+ header->signature = cpu_to_le64(GPT_HEADER_SIGNATURE);
+ header->revision = cpu_to_le32(GPT_HEADER_REVISION_V1_00);
+ header->size = cpu_to_le32(sizeof(struct gpt_header));
+
+ /*
+ * 128 partitions is the default. It can go behond this, however,
+ * we're creating a de facto header here, so no funny business.
+ */
+ header->npartition_entries = cpu_to_le32(GPT_NPARTITIONS);
+ header->sizeof_partition_entry = cpu_to_le32(sizeof(struct gpt_entry));
+ header->first_usable_lba = cpu_to_le64(esz + 2);
+ header->last_usable_lba = cpu_to_le64(cxt->total_sectors - 2 - esz);
+
+ gpt_mknew_header_common(cxt, header, lba);
+ uuid_generate_random((unsigned char *) &header->disk_guid);
+ swap_efi_guid(&header->disk_guid);
+
+ return 0;
+}
+
+/*
* Checks if there is a valid protective MBR partition table.
* Returns 0 if it is invalid or failure. Otherwise, return
* GPT_MBR_PROTECTIVE or GPT_MBR_HYBRID, depeding on the detection.
@@ -850,6 +969,22 @@ static void gpt_init(void)
partitions = le32_to_cpu(pheader->npartition_entries);
}
+/*
+ * Deinitialize fdisk-specific variables
+ */
+static void gpt_deinit(void)
+{
+ free(ents);
+ free(pheader);
+ free(bheader);
+ ents = NULL;
+ pheader = NULL;
+ bheader = NULL;
+
+ disklabel = ANY_LABEL;
+ partitions = 0;
+}
+
static int gpt_probe_label(struct fdisk_context *cxt)
{
int mbr_type;
@@ -899,6 +1034,7 @@ static char *encode_to_utf8(unsigned char *src, size_t count)
uint16_t c;
char *dest = xmalloc(count * sizeof(char));
size_t i, j, len = count;
+
memset(dest, 0, sizeof(char) * count);
for (j = i = 0; i + 2 <= count; i += 2) {
@@ -1363,6 +1499,60 @@ static void gpt_add_partition(struct fdisk_context *cxt, int partnum,
printf(_("Created partition %d\n"), partnum + 1);
}
+/*
+ * Create a new GPT disklabel - destroys any previous data.
+ */
+static int gpt_create_disklabel(struct fdisk_context *cxt)
+{
+ int rc = 0;
+ ssize_t entry_sz = 0;
+
+ /*
+ * Reset space or clear data from headers, pt entries and
+ * protective MBR. Big fat warning: any previous content is
+ * overwritten, so ask users to be sure!.
+ *
+ * When no header, entries or pmbr is set, we're probably
+ * dealing with a new, empty disk - so always allocate memory
+ * to deal with the data structures whatever the case is.
+ */
+ gpt_deinit();
+
+ rc = gpt_mknew_pmbr(cxt);
+ if (rc < 0)
+ goto done;
+
+ pheader = xcalloc(1, sizeof(*pheader));
+ rc = gpt_mknew_header(cxt, pheader, GPT_PRIMARY_PARTITION_TABLE_LBA);
+ if (rc < 0)
+ goto done;
+
+ bheader = xcalloc(1, sizeof(*bheader));
+ rc = gpt_mknew_header_from_bkp(cxt, bheader, last_lba(cxt), pheader);
+ if (rc < 0)
+ goto done;
+
+ entry_sz = le32_to_cpu(pheader->npartition_entries) *
+ le32_to_cpu(pheader->sizeof_partition_entry);
+ ents = xcalloc(1, sizeof(*ents) * entry_sz);
+
+ gpt_recompute_crc(pheader, ents);
+ gpt_recompute_crc(bheader, ents);
+
+ gpt_init();
+ DBG(LABEL, dbgprint("created new empty GPT disklabel "
+ "(GUID: %08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X)",
+ pheader->disk_guid.time_low, pheader->disk_guid.time_mid,
+ pheader->disk_guid.time_hi_and_version,
+ pheader->disk_guid.clock_seq_hi,
+ pheader->disk_guid.clock_seq_low,
+ pheader->disk_guid.node[0], pheader->disk_guid.node[1],
+ pheader->disk_guid.node[2], pheader->disk_guid.node[3],
+ pheader->disk_guid.node[4], pheader->disk_guid.node[5]));
+done:
+ return rc;
+}
+
static struct fdisk_parttype *gpt_get_partition_type(struct fdisk_context *cxt,
int i)
{
@@ -1409,7 +1599,7 @@ const struct fdisk_label gpt_label =
.probe = gpt_probe_label,
.write = gpt_write_disklabel,
.verify = gpt_verify_disklabel,
- .create = NULL,
+ .create = gpt_create_disklabel,
.part_add = gpt_add_partition,
.part_delete = gpt_delete_partition,
.part_get_type = gpt_get_partition_type,
--
1.7.9.5
--
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