/* gpt.c - Read GUID Partition Tables (GPT).  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2002,2005,2006,2007,2008  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *(at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <r_types.h>
#include <grub/disk.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/partition.h>
#include <grub/msdos_partition.h>
#include <grub/gpt_partition.h>

static grub_uint8_t grub_gpt_magic[8] = {
	0x45, 0x46, 0x49, 0x20, 0x50, 0x41, 0x52, 0x54
};

static const grub_gpt_part_type_t grub_gpt_partition_type_empty = GRUB_GPT_PARTITION_TYPE_EMPTY;

struct grub_partition_map grub_gpt_partition_map;

static grub_err_t
gpt_partition_map_iterate(grub_disk_t disk,
	int (*hook) (grub_disk_t disk,
		const grub_partition_t partition,
		void *closure),
	void *closure) {
	struct grub_partition part;
	struct grub_gpt_header gpt;
	struct grub_gpt_partentry entry;
	struct grub_msdos_partition_mbr mbr;
	grub_uint64_t entries;
	unsigned int i;
	int last_offset = 0;

	/* Read the protective MBR.  */
	if (grub_disk_read (disk, 0, 0, sizeof (mbr), &mbr)) {
		return grub_errno;
	}

	/* Check if it is valid.  */
	if (mbr.signature != grub_cpu_to_le16 (GRUB_PC_PARTITION_SIGNATURE)) {
		return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
	}

	/* Make sure the MBR is a protective MBR and not a normal MBR.  */
	if (mbr.entries[0].type != GRUB_PC_PARTITION_TYPE_GPT_DISK) {
		return grub_error (GRUB_ERR_BAD_PART_TABLE, "no GPT partition map found");
	}

	/* Read the GPT header.  */
	if (grub_disk_read (disk, 1, 0, sizeof (gpt), &gpt)) {
		return grub_errno;
	}

	if (memcmp (gpt.magic, grub_gpt_magic, sizeof (grub_gpt_magic))) {
		return grub_error (GRUB_ERR_BAD_PART_TABLE, "no valid GPT header");
	}

	grub_dprintf ("gpt", "Read a valid GPT header\n");

	entries = grub_le_to_cpu64 (gpt.partitions);
	for (i = 0; i < grub_le_to_cpu32 (gpt.maxpart); i++) {
		if (grub_disk_read (disk, entries, last_offset, sizeof (entry), &entry)) {
			return grub_errno;
		}

		if (memcmp (&grub_gpt_partition_type_empty, &entry.type, sizeof (grub_gpt_partition_type_empty))) {
			/* Calculate the first block and the size of the partition.  */
			memset (&part, 0, sizeof (struct grub_partition));
			part.start = grub_le_to_cpu64 (entry.start);
			part.len = (grub_le_to_cpu64 (entry.end) - grub_le_to_cpu64 (entry.start) + 1);
			part.offset = entries;
			part.number = i;
			part.index = last_offset;
			part.msdostype = 0; // TODO entry.type.data1;
			part.partmap = &grub_gpt_partition_map;

			grub_dprintf ("gpt", "GPT entry %d: start=%" PFMT64d ", length=%" PFMT64d "\n", i, (ut64)part.start, (ut64)part.len);

			if (hook (disk, &part, closure)) {
				return grub_errno;
			}
		}

		last_offset += grub_le_to_cpu32 (gpt.partentry_size);
		if (last_offset == GRUB_DISK_SECTOR_SIZE) {
			last_offset = 0;
			entries++;
		}
	}

	return GRUB_ERR_NONE;
}

/* Partition map type.  */
struct grub_partition_map grub_gpt_partition_map = {
	.name = "gpt",
	.iterate = gpt_partition_map_iterate,
};
