fs_ext2.c

Hermit-at-1.1.3,一款bootloader

#include <target/io.h>
#include <target/herrno.h>
#include <target/htypes.h>
#include <target/memcmp.h>

#include "ide_core.h"
#include "fs_ext2.h"

#define CORE_NAME "ext2"

#undef DEBUG
#if defined(DEBUG)
#define DEBUG_FUNC()        hprintf("*" CORE_NAME ": %s()\n", __FUNCTION__)
#define DEBUG_INFO(args...) hprintf("*" CORE_NAME ": " args)
#define DEBUG_ERR(args...)  hprintf("*" CORE_NAME ": " args)
#define DEBUG_RAW(args...)  hprintf(args)
#else
#define DEBUG_FUNC()
#define DEBUG_INFO(args...)
#define DEBUG_ERR(args...)
#define DEBUG_RAW(args...)
#endif
#define PRINT_INFO(args...) hprintf(CORE_NAME ": " args)
#define PRINT_ERR(args...)  hprintf(CORE_NAME ": " args)
#define PRINT_RAW(args...)  hprintf(args)

/****************************************************************************
 * 
 ****************************************************************************/
int
ext2_find_image(ide_info_t *info, file_t *file, ext2_super_block_t *sb)
{
	ext2_group_desc_t *ext2gd;
	ext2_inode_t *ext2inode;
	ext2_dir_entry_t *ext2de;

	u32 sectors_per_block;
	u32 blocks_per_group, inodes_per_group, group_desc_sector;
	u32 first_inode_table, inode_table_sector;
	u32 dir_entry_table_sector;
	u32 group, inode;
	u8 buf[SECTOR_SIZE * 8];
	int  ext = 0;
	int ret;
	int i, j;

	DEBUG_FUNC();

	if (sb->s_inode_size != INODE_SIZE) {
		PRINT_ERR("Bad inode size.\n");
		return -H_EIO;
	}
	if (sb->s_log_block_size > 2) {
		PRINT_ERR("Bad block size.\n");
		return -H_EIO;
	}

	sectors_per_block = 2;
	for (i=0; i<sb->s_log_block_size; i++)
		sectors_per_block *= 2;
	blocks_per_group = sb->s_blocks_per_group;
	inodes_per_group = sb->s_inodes_per_group;
	group_desc_sector = (file->partition_start +
			     sectors_per_block * (1 + sb->s_first_data_block));

	ret = info->read_sectors(info, group_desc_sector, buf, 1);
	if (ret < 0) {
		PRINT_ERR("Group desc read error.\n");
		return -H_EIO;
	}
	ext2gd = (ext2_group_desc_t *)buf;
	first_inode_table = ext2gd->bg_inode_table;
	inode_table_sector = (file->partition_start +
			      sectors_per_block * first_inode_table);

	ret = info->read_sectors (info, inode_table_sector, buf, 1);
	if (ret < 0) {
		PRINT_ERR("Inode table read error.\n");
		return -H_EIO;
	}
	for (j = 0; j < SECTOR_SIZE; j += INODE_SIZE) {
		ext2inode = (ext2_inode_t *)(buf + j);
		if ((ext2inode->i_mode & 0xf000) == 0x4000) {
			break;
		}
	}
	if (j >= SECTOR_SIZE) {
		PRINT_ERR("Can't find root.\n");
		return -H_EIO;
	}

	dir_entry_table_sector = (file->partition_start +
				  sectors_per_block * ext2inode->i_block[0]);
	ret = info->read_sectors(info, dir_entry_table_sector, buf,
				 sectors_per_block);
	if (ret < 0) {
		PRINT_ERR("Root directory entry read error.\n");
		return -H_EIO;
	}

	ext2de = (ext2_dir_entry_t *)buf;
	for (;
	     ((addr_t)ext2de - (addr_t)buf) <= 
	       (SECTOR_SIZE * sectors_per_block - 12);
	     (ext2de = (ext2_dir_entry_t *)(((addr_t)ext2de) +
					    ext2de->rec_len))) {
		if (!ext2de->rec_len)
			break;

		if (ext2de->name_len == 4)
			if (!memcmp (ext2de->name, "boot", 4))
				break;
	}
	if ((addr_t)ext2de - (addr_t)buf >
	    SECTOR_SIZE * sectors_per_block - 12 ||
	    !ext2de->rec_len) {
		PRINT_ERR("Can't find /boot\n");
		return -H_EIO;
	}

	group = (ext2de->inode - 1) / inodes_per_group;
	inode = (ext2de->inode - 1) % inodes_per_group;
	inode_table_sector = (file->partition_start + sectors_per_block *
			      (blocks_per_group * group + first_inode_table) +
			      inode / (SECTOR_SIZE / INODE_SIZE));
	ret = info->read_sectors (info, inode_table_sector, buf, 1);
	if (ret < 0) {
		PRINT_ERR("Inode table read error.\n");
		return -H_EIO;
	}
	ext2inode = (ext2_inode_t *)
		(buf + INODE_SIZE * (inode % (SECTOR_SIZE / INODE_SIZE)));
	if ((ext2inode->i_mode & 0xf000) != 0x4000) {
		PRINT_ERR("/boot is not directory.\n");
		return -H_EIO;
	}

	dir_entry_table_sector = (file->partition_start +
				  sectors_per_block * ext2inode->i_block[0]);
	ret = info->read_sectors(info, dir_entry_table_sector, buf,
				 sectors_per_block);
	if (ret < 0) {
		PRINT_ERR("/boot directory entry read error.\n");
		return -H_EIO;
	}

	for (ext2de = (ext2_dir_entry_t *)buf;
	     ((addr_t)ext2de - (addr_t)buf) <=
	       (SECTOR_SIZE * sectors_per_block - 16);
	     ext2de = (ext2_dir_entry_t *)(((addr_t)ext2de) +
					   ext2de->rec_len)) {
		if (!ext2de->rec_len)
			break;

		ext = 0;
		if (ext2de->name_len >= 5) {
			if (!memcmp(ext2de->name, "Image", 5) ||
			    !memcmp(ext2de->name, "linux", 5)) {
				if (ext2de->name_len == 5)
					break;

				if (ext2de->name_len >= 9) {
					if (!memcmp(ext2de->name + 5,
						    ".bin", 4)) {
						ext = 4;
						if (ext2de->name_len == 9)
							break;
					}
				}
				if (ext2de->name_len == 5 + ext + 3) {
					if (!memcmp(ext2de->name + 5 + ext,
						    ".gz", 3)) {
						file->compressed = 1;
						break;
					}
				}
			}
		}
	}
	
	if ((((addr_t)ext2de - (addr_t)buf) >
	    (SECTOR_SIZE * sectors_per_block - 16)) || 
	    !ext2de->rec_len) {
		PRINT_ERR("Can't find /boot/Image(or linux)(.bin)(.gz)\n");
		return -H_EIO;
	}

	memcpy (file->name, ext2de->name, ext2de->name_len);
	file->name[ext2de->name_len] = '\0';
	group = (ext2de->inode - 1) / inodes_per_group;
	inode = (ext2de->inode - 1) % inodes_per_group;
	inode_table_sector = (file->partition_start +
			      sectors_per_block *
			      (blocks_per_group * group + first_inode_table) +
			      inode / (SECTOR_SIZE / INODE_SIZE));
	ret = info->read_sectors (info, inode_table_sector, buf, 1);
	if (ret < 0) {
		PRINT_ERR("Inode table read error.\n");
		return -H_EIO;
	}

	ext2inode = (ext2_inode_t *)(buf + INODE_SIZE * 
				     (inode % (SECTOR_SIZE / INODE_SIZE)));
	if ((ext2inode->i_mode & 0xf000) != 0x8000) {
		PRINT_ERR("%s is not file.\n", file->name);
		return -H_EIO;
	}

	file->size = ext2inode->i_size;
	if (file->size <= 0) {
		PRINT_ERR("%s size is zero.\n", file->name);
		return -H_EIO;
	}

	for (j = 0; j < 15; j++)
		file->blocks[j] = ext2inode->i_block[j];

	return 0;
}