--- /dev/null
+/*
+ * EFI GPT partition parsing code
+ *
+ * Copyright (C) 2009 Karel Zak <kzak@redhat.com>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ *
+ * This code is not copy & past from any other implementation.
+ *
+ * For more information about GPT start your study at:
+ * http://en.wikipedia.org/wiki/GUID_Partition_Table
+ * http://technet.microsoft.com/en-us/library/cc739412(WS.10).aspx
+ */
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stddef.h>
+
+#include "partitions.h"
+#include "crc32.h"
+#include "dos.h"
+
+#define GPT_PRIMARY_LBA 1
+#define GPT_BLOCK_SIZE 512
+
+/* Signature - “EFI PART” */
+#define GPT_HEADER_SIGNATURE 0x5452415020494645ULL
+
+/* basic types */
+typedef uint16_t efi_char16_t;
+
+/* UUID */
+typedef struct {
+ uint8_t b[16];
+} efi_guid_t;
+
+#define EFI_GUID(a,b,c,d0,d1,d2,d3,d4,d5,d6,d7) ((efi_guid_t) \
+ {{ \
+ (a) & 0xff, ((a) >> 8) & 0xff, ((a) >> 16) & 0xff, ((a) >> 24) & 0xff, \
+ (b) & 0xff, ((b) >> 8) & 0xff, \
+ (c) & 0xff, ((c) >> 8) & 0xff, \
+ (d0), (d1), (d2), (d3), (d4), (d5), (d6), (d7) \
+}})
+
+#define GPT_UNUSED_ENTRY_GUID EFI_GUID(0x00000000, 0x0000, 0x0000, 0x00, 0x00, \
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
+
+struct gpt_header {
+ uint64_t signature; /* "EFI PART" */
+ uint32_t revision;
+ uint32_t header_size; /* usualy 92 bytes */
+ uint32_t header_crc32; /* checksum of header with this
+ * field zeroed during calculation */
+ uint32_t reserved1;
+
+ uint64_t my_lba; /* location of this header copy */
+ uint64_t alternate_lba; /* location of the other header copy */
+ uint64_t first_usable_lba; /* lirst usable LBA for partitions */
+ uint64_t last_usable_lba; /* last usable LBA for partitions */
+
+ efi_guid_t disk_guid; /* disk UUID */
+
+ uint64_t partition_entries_lba; /* always 2 in primary header copy */
+ uint32_t num_partition_entries;
+ uint32_t sizeof_partition_entry;
+ uint32_t partition_entry_array_crc32;
+
+ uint8_t reserved2[GPT_BLOCK_SIZE - 92];
+} __attribute__ ((packed));
+
+/*** not used
+struct gpt_entry_attributes {
+ uint64_t required_to_function:1;
+ uint64_t reserved:47;
+ uint64_t type_guid_specific:16;
+} __attribute__ ((packed));
+***/
+
+struct gpt_entry {
+ efi_guid_t partition_type_guid; /* type UUID */
+ efi_guid_t unique_partition_guid; /* partition UUID */
+ uint64_t starting_lba;
+ uint64_t ending_lba;
+
+ /*struct gpt_entry_attributes attributes;*/
+
+ uint64_t attributes;
+
+ efi_char16_t partition_name[72 / sizeof(efi_char16_t)]; /* UTF-16LE string*/
+} __attribute__ ((packed));
+
+
+/*
+ * EFI uses crc32 with ~0 seed and xor's with ~0 at the end.
+ */
+static inline uint32_t count_crc32(const unsigned char *buf, size_t len)
+{
+ return (crc32(~0L, buf, len) ^ ~0L);
+}
+
+static inline unsigned char *get_lba_buffer(blkid_probe pr,
+ uint64_t lba, size_t bytes)
+{
+ return blkid_probe_get_buffer(pr,
+ GPT_BLOCK_SIZE * lba, bytes);
+}
+
+static inline int guidcmp(efi_guid_t left, efi_guid_t right)
+{
+ return memcmp(&left, &right, sizeof (efi_guid_t));
+}
+
+static int last_lba(blkid_probe pr, uint64_t *lba)
+{
+ blkid_loff_t sz = blkid_probe_get_size(pr);
+ if (sz < GPT_BLOCK_SIZE)
+ return -1;
+
+ *lba = (sz >> 9) - 1;
+ return 0;
+}
+
+/*
+ * Protective (legacy) MBR.
+ *
+ * This MBR contains standard DOS partition table with a single partition, type
+ * of 0xEE. The partition usually encompassing the entire GPT drive - or 2TiB
+ * for large disks.
+ *
+ * Note that Apple uses GPT/MBR hybrid disks, where the DOS partition table is
+ * synchronized with GPT. This synchronization has many restriction of course
+ * (due DOS PT limitations).
+ *
+ * Note that the PMBR detection is optional (enabled by default) and could be
+ * disabled by BLKID_PARTS_FOPCE_GPT flag (see also blkid_paertitions_set_flags()).
+ */
+static int is_pmbr_valid(blkid_probe pr)
+{
+ int flags = blkid_partitions_get_flags(pr);
+ unsigned char *data;
+ struct dos_partition *p;
+ int i;
+
+ if (flags & BLKID_PARTS_FORCE_GPT)
+ goto ok; /* skip PMBR check */
+
+ data = blkid_probe_get_sector(pr, 0);
+ if (!data)
+ goto failed;
+
+ if (!is_valid_mbr_signature(data))
+ goto failed;
+
+ p = (struct dos_partition *) (data + BLKID_MSDOS_PT_OFFSET);
+
+ for (i = 0; i < 4; i++, p++) {
+ if (p->sys_type == BLKID_GPT_PARTITION)
+ goto ok;
+ }
+failed:
+ return 0;
+ok:
+ return 1;
+}
+
+/*
+ * Reads GPT header to @hdr and returns a pointer to @hdr or NULL in case of
+ * error. The function also returns GPT entries in @ents.
+ *
+ * Note, this function does not allocate any memory. The GPT header has fixed
+ * size so we use stack, and @ents returns memory from libblkid buffer (so the
+ * next blkid_probe_get_buffer() will overwrite this buffer).
+ *
+ * This function checks validity of header and entries array. A corrupted
+ * header is not returned.
+ */
+static struct gpt_header *get_gpt_header(
+ blkid_probe pr, struct gpt_header *hdr,
+ struct gpt_entry **ents, uint64_t lba,
+ uint64_t lastlba)
+{
+ struct gpt_header *h;
+ uint32_t crc, orgcrc;
+ uint64_t lu, fu;
+ size_t esz;
+
+ h = (struct gpt_header *) get_lba_buffer(pr, lba, sizeof(*h));
+ if (!h)
+ return NULL;
+
+ if (le64_to_cpu(h->signature) != GPT_HEADER_SIGNATURE)
+ return NULL;
+
+ /* Header has to be verified when header_crc32 is zero */
+ orgcrc = le32_to_cpu(h->header_crc32);
+ h->header_crc32 = 0;
+
+ crc = count_crc32((unsigned char *) h, le32_to_cpu(h->header_size));
+ if (crc != orgcrc) {
+ DBG(DEBUG_LOWPROBE, printf("GPT header corrupted\n"));
+ return NULL;
+ }
+ h->header_crc32 = cpu_to_le32(orgcrc);
+
+ /* Valid header has to be at MyLBA */
+ if (le64_to_cpu(h->my_lba) != lba) {
+ DBG(DEBUG_LOWPROBE, printf(
+ "GPT->MyLBA mismatch with real position\n"));
+ return NULL;
+ }
+
+ fu = le64_to_cpu(h->first_usable_lba);
+ lu = le64_to_cpu(h->last_usable_lba);
+
+ /* Check if First and Last usable LBA makes sense */
+ if (lu < fu || fu > lastlba || lu > lastlba) {
+ DBG(DEBUG_LOWPROBE, printf(
+ "GPT->{First,Last}UsableLBA out of range\n"));
+ return NULL;
+ }
+
+ /* The header has to be outside usable range */
+ if (fu < lba && lba < lu) {
+ DBG(DEBUG_LOWPROBE, printf("GPT header is inside usable area\n"));
+ return NULL;
+ }
+
+ /* Size of blocks with GPT entries */
+ esz = le32_to_cpu(h->num_partition_entries) *
+ le32_to_cpu(h->sizeof_partition_entry);
+ if (!esz) {
+ DBG(DEBUG_LOWPROBE, printf("GPT entries undefined\n"));
+ return NULL;
+ }
+
+ /* The header seems valid, save it */
+ memcpy(hdr, h, sizeof(*h));
+ h = hdr;
+
+ /* Read GPT entries */
+ *ents = (struct gpt_entry *) get_lba_buffer(pr,
+ le64_to_cpu(h->partition_entries_lba), esz);
+ if (!*ents) {
+ DBG(DEBUG_LOWPROBE, printf("GPT entries unreadable\n"));
+ return NULL;
+ }
+
+ /* Validate entries */
+ crc = count_crc32((unsigned char *) *ents, esz);
+ if (crc != le32_to_cpu(h->partition_entry_array_crc32)) {
+ DBG(DEBUG_LOWPROBE, printf("GPT entries corrupted\n"));
+ return NULL;
+ }
+
+ return h;
+}
+
+static int probe_gpt_pt(blkid_probe pr, const struct blkid_idmag *mag)
+{
+ uint64_t lastlba, lba;
+ struct gpt_header hdr, *h;
+ struct gpt_entry *e;
+ blkid_parttable tab = NULL;
+ blkid_partlist ls;
+ int i;
+ uint64_t fu, lu;
+
+
+ if (last_lba(pr, &lastlba))
+ goto nothing;
+
+ if (!is_pmbr_valid(pr))
+ goto nothing;
+
+ h = get_gpt_header(pr, &hdr, &e, (lba = GPT_PRIMARY_LBA), lastlba);
+ if (!h)
+ h = get_gpt_header(pr, &hdr, &e, (lba = lastlba), lastlba);
+
+ if (!h)
+ goto nothing;
+
+ if (blkid_partitions_need_typeonly(pr))
+ /* caller does not ask for details about partitions */
+ return 0;
+
+ ls = blkid_probe_get_partlist(pr);
+ if (!ls)
+ goto err;
+
+ tab = blkid_partlist_new_parttable(ls, "gpt", lba << 9);
+ if (!tab)
+ goto err;
+
+ fu = le64_to_cpu(h->first_usable_lba);
+ lu = le64_to_cpu(h->last_usable_lba);
+
+ for (i = 0; i < le32_to_cpu(h->num_partition_entries); i++, e++) {
+
+ blkid_partition par;
+ uint64_t start = le64_to_cpu(e->starting_lba);
+ uint64_t size = le64_to_cpu(e->ending_lba) -
+ le64_to_cpu(e->starting_lba);
+
+ /* 00000000-0000-0000-0000-000000000000 entry */
+ if (!guidcmp(e->partition_type_guid, GPT_UNUSED_ENTRY_GUID))
+ continue;
+
+ /* the partition has to inside usable range */
+ if (start < fu || start + size > lu) {
+ DBG(DEBUG_LOWPROBE, printf(
+ "GPT entry[%d] overflows usable area - ignore\n",
+ i));
+ continue;
+ }
+
+ par = blkid_partlist_add_partition(ls, tab, 0, start, size);
+ if (!par)
+ goto err;
+
+ blkid_partition_set_utf8name(par, (unsigned char *) e->partition_name,
+ sizeof(e->partition_name), BLKID_ENC_UTF16LE);
+
+ blkid_partition_set_uuid(par,
+ (const unsigned char *) &e->unique_partition_guid);
+ }
+
+ return 0;
+
+nothing:
+ return 1;
+err:
+ return -1;
+}
+
+
+const struct blkid_idinfo gpt_pt_idinfo =
+{
+ .name = "gpt",
+ .probefunc = probe_gpt_pt,
+
+ /*
+ * It would be possible to check for DOS signature (0xAA55), but
+ * unfortunately almost all EFI GPT implemenations allow to optionaly
+ * skip the legacy MBR. We follows this behavior and MBR is optional.
+ * See is_valid_pmbr().
+ *
+ * It would be possible to check for "EFI PART" at begin of the disk,
+ * but the primary GPT is not required (in force mode).
+ *
+ * It means we have to always call probe_gpt_pt().
+ */
+ .magics = BLKID_NONE_MAGIC
+};
+
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