path: root/src/gpt.c

/*
 * Copyright (C) 2016 Paul Kocialkowski <contact@paulk.fr>
 *
 * This program 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.
 *
 * This program is distributed in the hope that it will be usefu,
 * 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>

#include "lg-downloader.h"
#include "download.h"
#include "gpt.h"

/* Lookup table for CRC32 with generator polynomial 0x04c11db7. */
static const uint32_t gpt_crc_table[] = {
	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
	0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
	0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
	0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
	0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
	0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
	0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
	0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
	0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
	0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
	0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
	0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
	0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
	0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
	0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
	0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
	0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
	0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
	0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
	0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
	0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
	0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
	0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
	0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
	0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
	0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
	0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
	0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
	0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
	0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
	0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
	0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
	0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
	0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
	0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
	0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
	0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
	0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
	0x2d02ef8d
};

static uint32_t gpt_crc_step(uint32_t crc, uint8_t data)
{
	return ((crc >> 8) ^ gpt_crc_table[(crc ^ data) & 0xff]);
}

static uint32_t gpt_crc_final(uint32_t crc)
{
	return crc ^ GPT_CRC_SEED;
}

static void gpt_partition_name(struct gpt_partition *partition, char *name)
{
	size_t i;
	size_t j;
	char c;

	if (partition == NULL || name == NULL)
		return;

	for (i = 0, j = 0; i < GPT_PARTITION_NAME_COUNT; i++) {
		c = (char) le16toh(partition->name[i]);

		if (isprint(c))
			name[j++] = c;
	}

	name[j] = '\0';
}

int gpt_header_verify(struct gpt_header *header)
{
	struct gpt_header header_copy;
	uint8_t *p;
	uint32_t crc;
	size_t i;

	if (header == NULL)
		return -1;

	if (strncmp(header->signature, GPT_SIGNATURE, sizeof(header->signature)) != 0) {
		fprintf(stderr, "Verifying GPT signature failed\n");
		return -1;
	}

	if (le32toh(header->version) != GPT_VERSION) {
		fprintf(stderr, "Verifying GPT version failed\n");
		return -1;
	}

	memcpy(&header_copy, header, sizeof(struct gpt_header));
	header_copy.crc = 0;

	crc = GPT_CRC_SEED;
	p = (uint8_t *) &header_copy;

	for (i = 0; i < sizeof(struct gpt_header); i++)
		crc = gpt_crc_step(crc, *p++);

	crc = gpt_crc_final(crc);

	if (le32toh(header->crc) != crc) {
		fprintf(stderr, "Verifying GPT CRC failed\n");
		return -1;
	}

	if (le32toh(header->partitions_size) != sizeof(struct gpt_partition))
		return -1;

	if ((GPT_BLOCK_SIZE % le32toh(header->partitions_size)) != 0)
		return -1;

	if (le32toh(header->partitions_lba) == 0 || le32toh(header->partitions_count) == 0)
		return -1;

	return 0;
}

int gpt_header_read(struct context *context, struct gpt_header *header)
{
	off_t address;
	size_t length;
	int rc;

	address = GPT_HEADER_LBA;
	length = sizeof(struct gpt_header);

	rc = download_ready_read(context, address, length);
	if (rc < 0)
		return -1;

	rc = download_read(context, (void *) header, length);
	if (rc < 0)
		return -1;

	return 0;
}

int gpt_partition_find(struct context *context)
{
	struct gpt_header header;
	struct gpt_partition *partition;
	void *buffer = NULL;
	char name[GPT_PARTITION_NAME_COUNT + 1];
	off_t address;
	size_t length;
	size_t count;
	size_t index;
	size_t i;
	int rc;

	if (context == NULL || context->partition == NULL)
		return -1;

	if (context->verbose)
		printf("Reading GPT header\n");

	rc = gpt_header_read(context, &header);
	if (rc < 0) {
		fprintf(stderr, "Reading GPT header failed\n");
		goto error;
	}

	if (context->verbose)
		printf("Verifying GPT header\n");

	rc = gpt_header_verify(&header);
	if (rc < 0) {
		fprintf(stderr, "Verifying GPT header failed\n");
		goto error;
	}

	address = le32toh(header.partitions_lba);
	length = le32toh(header.partitions_size);
	count = le32toh(header.partitions_count);

	buffer = calloc(1, GPT_BLOCK_SIZE);

	for (i = 0; i < count; i++) {
		index = i % (GPT_BLOCK_SIZE / length);

		if (index == 0) {
			rc = download_ready_read(context, address, GPT_BLOCK_SIZE);
			if (rc < 0)
				goto error;

			rc = download_read(context, buffer, GPT_BLOCK_SIZE);
			if (rc < 0)
				goto error;

			address++;
		}

		partition = ((struct gpt_partition *) buffer) + index;

		gpt_partition_name(partition, (char *) &name);

		if (name[0] != '\0') {
			if (context->verbose)
				printf("Found GPT partition: %s\n", name);

			if (strcmp(name, context->partition) == 0) {
				if (context->verbose)
					printf("Matched GPT partition: %s\n", name);

				context->address = (uint32_t) le64toh(partition->first_lba);
				context->length = (uint32_t) (le64toh(partition->last_lba) - le64toh(partition->first_lba) + 1) * GPT_BLOCK_SIZE;

				rc = 0;
				goto complete;
			}

		}
	}

	fprintf(stderr, "Matching GPT partition: %s failed\n", context->partition);

error:
	rc = -1;

complete:
	if (buffer != NULL)
		free(buffer);

	return rc;
}

int gpt_partitions_print(struct context *context)
{
	struct gpt_header header;
	struct gpt_partition *partition;
	void *buffer = NULL;
	char name[GPT_PARTITION_NAME_COUNT + 1];
	off_t address;
	size_t length;
	size_t count;
	size_t index;
	size_t i;
	int rc;

	if (context == NULL)
		return -1;

	if (context->verbose)
		printf("Reading GPT header\n");

	rc = gpt_header_read(context, &header);
	if (rc < 0) {
		fprintf(stderr, "Reading GPT header failed\n");
		goto error;
	}

	if (context->verbose)
		printf("Verifying GPT header\n");

	rc = gpt_header_verify(&header);
	if (rc < 0) {
		fprintf(stderr, "Verifying GPT header failed\n");
		goto error;
	}

	address = le32toh(header.partitions_lba);
	length = le32toh(header.partitions_size);
	count = le32toh(header.partitions_count);

	buffer = calloc(1, GPT_BLOCK_SIZE);

	for (i = 0; i < count; i++) {
		index = i % (GPT_BLOCK_SIZE / length);

		if (index == 0) {
			rc = download_ready_read(context, address, GPT_BLOCK_SIZE);
			if (rc < 0)
				goto error;

			rc = download_read(context, buffer, GPT_BLOCK_SIZE);
			if (rc < 0)
				goto error;

			address++;
		}

		partition = ((struct gpt_partition *) buffer) + index;

		gpt_partition_name(partition, (char *) &name);

		if (name[0] != '\0')
			printf("Partition name: %s, size: %d bytes\n", name, (int) (le64toh(partition->last_lba) - le64toh(partition->first_lba) + 1) * GPT_BLOCK_SIZE);
	}

	rc = 0;
	goto complete;

error:
	rc = -1;

complete:
	if (buffer != NULL)
		free(buffer);

	return rc;
}