util/cbfstool/cbfs_image.c

/*
 * CBFS Image Manipulation
 *
 * Copyright (C) 2013 The Chromium OS Authors. All rights reserved.
 *
 * 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; version 2 of the License.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "common.h"
#include "cbfs_image.h"

/* The file name align is not defined in CBFS spec -- only a preference by
 * (old) cbfstool. */
#define CBFS_FILENAME_ALIGN	(16)

/* To make CBFS more friendly to ROM, fill -1 (0xFF) instead of zero. */
#define CBFS_CONTENT_DEFAULT_VALUE	(-1)

static uint32_t align_up(uint32_t value, uint32_t align) {
	if (value % align)
		value += align - (value % align);
	return value;
}

int cbfs_image_from_file(struct cbfs_image *image, const char *filename) {
	if (buffer_from_file(&image->buffer, filename) != 0)
		return -1;
	DEBUG("read_cbfs_image: %s (%zd bytes)\n", image->buffer.name,
	      image->buffer.size);
	image->header = cbfs_find_header(image->buffer.data,
					 image->buffer.size);
	if (!image->header) {
		ERROR("%s does not have CBFS master header.\n", filename);
		cbfs_image_delete(image);
		return -1;
	}

	return 0;
}

int cbfs_image_write_file(struct cbfs_image *image, const char *filename) {
	assert(image && image->buffer.data);
	return buffer_write_file(&image->buffer, filename);
}

int cbfs_image_delete(struct cbfs_image *image) {
	buffer_delete(&image->buffer);
	image->header = NULL;
	return 0;
}

struct cbfs_header *cbfs_find_header(char *data, size_t size) {
	size_t offset;
	int found = 0;
	uint32_t x86sig;
	struct cbfs_header *header, *result = NULL;

	// Try x86 style (check signature in bottom) header first.
	x86sig = *(uint32_t *)(data + size - sizeof(uint32_t));
	offset = (x86sig + (uint32_t)size);
	DEBUG("x86sig: 0x%x, offset: 0x%zx\n", x86sig, offset);
	if (offset >= size - sizeof(*header) ||
	    ntohl(((struct cbfs_header *)(data + offset))->magic) !=
	    CBFS_HEADER_MAGIC)
		offset = 0;

	for (; offset + sizeof(*header) < size; offset++) {
		header = (struct cbfs_header *)(data + offset);
		if (ntohl(header->magic) !=(CBFS_HEADER_MAGIC))
		    continue;
		if (ntohl(header->version) != CBFS_HEADER_VERSION1 &&
		    ntohl(header->version) != CBFS_HEADER_VERSION2) {
			// Probably not a real CBFS header?
			continue;
		}
		found++;
		result = header;
	}
	if (found > 1) {
		ERROR("multiple (%d) CBFS headers found!\n",
		       found);
		result = NULL;
	}
	return result;
}


struct cbfs_file *cbfs_find_first_entry(struct cbfs_image *image) {
	assert(image && image->header);
	return (struct cbfs_file *)(image->buffer.data +
				   ntohl(image->header->offset));
}

struct cbfs_file *cbfs_find_next_entry(struct cbfs_image *image,
				       struct cbfs_file *entry) {
	uint32_t addr = cbfs_get_entry_addr(image, entry);
	int align = ntohl(image->header->align);
	assert(entry && cbfs_is_valid_entry(entry));
	addr += ntohl(entry->offset) + ntohl(entry->len);
	addr = align_up(addr, align);
	return (struct cbfs_file *)(image->buffer.data + addr);
}

uint32_t cbfs_get_entry_addr(struct cbfs_image *image, struct cbfs_file *entry) {
	assert(image && image->buffer.data && entry);
	return (int32_t)((char *)entry - image->buffer.data);
}

int cbfs_is_valid_entry(struct cbfs_file *entry) {
	return (entry &&memcmp(entry->magic, CBFS_FILE_MAGIC,
			       sizeof(entry->magic)) == 0);
}