/* sunpc.c - Read SUN PC style partition tables.  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2002,2005,2006,2007,2009  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 <grub/partition.h>
#include <grub/disk.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/symbol.h>
#include <grub/types.h>
#include <grub/err.h>
#include <r_types.h>

#define GRUB_PARTMAP_SUN_PC_MAGIC 0xDABE
#define GRUB_PARTMAP_SUN_PC_MAX_PARTS 16
#define GRUB_PARTMAP_SUN_PC_WHOLE_DISK_ID 0x05

R_PACKED(
	struct grub_sun_pc_partition_descriptor {
		grub_uint16_t id;
		grub_uint16_t unused;
		grub_uint32_t start_sector;
		grub_uint32_t num_sectors;
	});

R_PACKED(
	struct grub_sun_pc_block {
		grub_uint8_t unused[72];
		struct grub_sun_pc_partition_descriptor partitions[GRUB_PARTMAP_SUN_PC_MAX_PARTS];
		grub_uint8_t unused2[244];
		grub_uint16_t magic; /* Magic number.  */
		grub_uint16_t csum; /* Label xor'd checksum.  */
	});

struct grub_partition_map grub_sun_pc_partition_map;

/* Verify checksum (true=ok).  */
static int
grub_sun_is_valid(struct grub_sun_pc_block *label) {
	grub_unaligned_uint16_t *pos;
	grub_uint16_t sum = 0;

	for (pos = (grub_uint16_t *)label;
		pos < (grub_uint16_t *) (label + 1);
		pos++) {
		sum ^= *pos;
	}

	return !sum;
}

static grub_err_t
sun_pc_partition_map_iterate(grub_disk_t disk,
	int (*hook) (grub_disk_t disk,
		const grub_partition_t partition,
		void *closure),
	void *closure) {
	grub_partition_t p;
	struct grub_sun_pc_block block;
	int partnum;
	grub_err_t err;

	p = (grub_partition_t)grub_zalloc (sizeof (struct grub_partition));
	if (!p) {
		return grub_errno;
	}

	p->partmap = &grub_sun_pc_partition_map;
	err = grub_disk_read (disk, 1, 0, sizeof (struct grub_sun_pc_block), &block);
	if (err) {
		grub_free (p);
		return err;
	}

	if (GRUB_PARTMAP_SUN_PC_MAGIC != grub_le_to_cpu16 (block.magic)) {
		grub_free (p);
		return grub_error (GRUB_ERR_BAD_PART_TABLE,
			"not a sun_pc partition table");
	}

	if (!grub_sun_is_valid (&block)) {
		grub_free (p);
		return grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid checksum");
	}

	/* Maybe another error value would be better, because partition
	table _is_ recognized but invalid.  */
	for (partnum = 0; partnum < GRUB_PARTMAP_SUN_PC_MAX_PARTS; partnum++) {
		struct grub_sun_pc_partition_descriptor *desc;

		if (block.partitions[partnum].id == 0 || block.partitions[partnum].id == GRUB_PARTMAP_SUN_PC_WHOLE_DISK_ID) {
			continue;
		}

		desc = &block.partitions[partnum];
		p->start = grub_le_to_cpu32 (desc->start_sector);
		p->len = grub_le_to_cpu32 (desc->num_sectors);
		p->number = partnum;
		if (p->len) {
			if (hook (disk, p, closure)) {
				partnum = GRUB_PARTMAP_SUN_PC_MAX_PARTS;
			}
		}
	}

	grub_free (p);

	return grub_errno;
}

/* Partition map type.  */
struct grub_partition_map grub_sun_pc_partition_map = {
	.name = "sunpc",
	.iterate = sun_pc_partition_map_iterate,
};