fs/ext2/ext2fs.c

/*
 * (C) Copyright 2004
 *  esd gmbh <www.esd-electronics.com>
 *  Reinhard Arlt <reinhard.arlt@esd-electronics.com>
 *
 *  based on code from grub2 fs/ext2.c and fs/fshelp.c by
 *
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2003, 2004  Free Software Foundation, Inc.
 *
 *  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 2 of the License, or
 *  (at your option) any later version.
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <common.h>
#include <ext2fs.h>
#include <malloc.h>
#include <asm/byteorder.h>

extern int ext2fs_devread (int sector, int byte_offset, int byte_len,
			   char *buf);

/* Magic value used to identify an ext2 filesystem.  */
#define	EXT2_MAGIC		0xEF53
/* Amount of indirect blocks in an inode.  */
#define INDIRECT_BLOCKS		12
/* Maximum lenght of a pathname.  */
#define EXT2_PATH_MAX		4096
/* Maximum nesting of symlinks, used to prevent a loop.  */
#define	EXT2_MAX_SYMLINKCNT	8

/* Filetype used in directory entry.  */
#define	FILETYPE_UNKNOWN	0
#define	FILETYPE_REG		1
#define	FILETYPE_DIRECTORY	2
#define	FILETYPE_SYMLINK	7

/* Filetype information as used in inodes.  */
#define FILETYPE_INO_MASK	0170000
#define FILETYPE_INO_REG	0100000
#define FILETYPE_INO_DIRECTORY	0040000
#define FILETYPE_INO_SYMLINK	0120000

/* Bits used as offset in sector */
#define DISK_SECTOR_BITS        9

/* Log2 size of ext2 block in 512 blocks.  */
#define LOG2_EXT2_BLOCK_SIZE(data) (__le32_to_cpu (data->sblock.log2_block_size) + 1)

/* Log2 size of ext2 block in bytes.  */
#define LOG2_BLOCK_SIZE(data)	   (__le32_to_cpu (data->sblock.log2_block_size) + 10)

/* The size of an ext2 block in bytes.  */
#define EXT2_BLOCK_SIZE(data)	   (1 << LOG2_BLOCK_SIZE(data))

/* The ext2 superblock.  */
struct ext2_sblock {
	uint32_t total_inodes;
	uint32_t total_blocks;
	uint32_t reserved_blocks;
	uint32_t free_blocks;
	uint32_t free_inodes;
	uint32_t first_data_block;
	uint32_t log2_block_size;
	uint32_t log2_fragment_size;
	uint32_t blocks_per_group;
	uint32_t fragments_per_group;
	uint32_t inodes_per_group;
	uint32_t mtime;
	uint32_t utime;
	uint16_t mnt_count;
	uint16_t max_mnt_count;
	uint16_t magic;
	uint16_t fs_state;
	uint16_t error_handling;
	uint16_t minor_revision_level;
	uint32_t lastcheck;
	uint32_t checkinterval;
	uint32_t creator_os;
	uint32_t revision_level;
	uint16_t uid_reserved;
	uint16_t gid_reserved;
	uint32_t first_inode;
	uint16_t inode_size;
	uint16_t block_group_number;
	uint32_t feature_compatibility;
	uint32_t feature_incompat;
	uint32_t feature_ro_compat;
	uint32_t unique_id[4];
	char volume_name[16];
	char last_mounted_on[64];
	uint32_t compression_info;
};

/* The ext2 blockgroup.  */
struct ext2_block_group {
	uint32_t block_id;
	uint32_t inode_id;
	uint32_t inode_table_id;
	uint16_t free_blocks;
	uint16_t free_inodes;
	uint16_t used_dir_cnt;
	uint32_t reserved[3];
};

/* The ext2 inode.  */
struct ext2_inode {
	uint16_t mode;
	uint16_t uid;
	uint32_t size;
	uint32_t atime;
	uint32_t ctime;
	uint32_t mtime;
	uint32_t dtime;
	uint16_t gid;
	uint16_t nlinks;
	uint32_t blockcnt;	/* Blocks of 512 bytes!! */
	uint32_t flags;
	uint32_t osd1;
	union {
		struct datablocks {
			uint32_t dir_blocks[INDIRECT_BLOCKS];
			uint32_t indir_block;
			uint32_t double_indir_block;
			uint32_t tripple_indir_block;
		} blocks;
		char symlink[60];
	} b;
	uint32_t version;
	uint32_t acl;
	uint32_t dir_acl;
	uint32_t fragment_addr;
	uint32_t osd2[3];
};

/* The header of an ext2 directory entry.  */
struct ext2_dirent {
	uint32_t inode;
	uint16_t direntlen;
	uint8_t namelen;
	uint8_t filetype;
};

struct ext2fs_node {
	struct ext2_data *data;
	struct ext2_inode inode;
	int ino;
	int inode_read;
};

/* Information about a "mounted" ext2 filesystem.  */
struct ext2_data {
	struct ext2_sblock sblock;
	struct ext2_inode *inode;
	struct ext2fs_node diropen;
};


typedef struct ext2fs_node *ext2fs_node_t;

struct ext2_data *ext2fs_root = NULL;
ext2fs_node_t ext2fs_file = NULL;
int symlinknest = 0;
uint32_t *indir1_block = NULL;
int indir1_size = 0;
int indir1_blkno = -1;
uint32_t *indir2_block = NULL;
int indir2_size = 0;
int indir2_blkno = -1;
static unsigned int inode_size;


static int ext2fs_blockgroup
	(struct ext2_data *data, int group, struct ext2_block_group *blkgrp) {
	unsigned int blkno;
	unsigned int blkoff;
	unsigned int desc_per_blk;

	desc_per_blk = EXT2_BLOCK_SIZE(data) / sizeof(struct ext2_block_group);

	blkno = __le32_to_cpu(data->sblock.first_data_block) + 1 +
	group / desc_per_blk;
	blkoff = (group % desc_per_blk) * sizeof(struct ext2_block_group);
#ifdef DEBUG
	printf ("ext2fs read %d group descriptor (blkno %d blkoff %d)\n",
		group, blkno, blkoff);
#endif
	return (ext2fs_devread (blkno << LOG2_EXT2_BLOCK_SIZE(data),
		blkoff, sizeof(struct ext2_block_group), (char *)blkgrp));

}


static int ext2fs_read_inode
	(struct ext2_data *data, int ino, struct ext2_inode *inode) {
	struct ext2_block_group blkgrp;
	struct ext2_sblock *sblock = &data->sblock;
	int inodes_per_block;
	int status;

	unsigned int blkno;
	unsigned int blkoff;

#ifdef DEBUG
	printf ("ext2fs read inode %d, inode_size %d\n", ino, inode_size);
#endif
	/* It is easier to calculate if the first inode is 0.  */
	ino--;
	status = ext2fs_blockgroup (data, ino / __le32_to_cpu
				    (sblock->inodes_per_group), &blkgrp);
	if (status == 0) {
		return (0);
	}

	inodes_per_block = EXT2_BLOCK_SIZE(data) / inode_size;

	blkno = __le32_to_cpu (blkgrp.inode_table_id) +
		(ino % __le32_to_cpu (sblock->inodes_per_group))
		/ inodes_per_block;
	blkoff = (ino % inodes_per_block) * inode_size;
#ifdef DEBUG
	printf ("ext2fs read inode blkno %d blkoff %d\n", blkno, blkoff);
#endif
	/* Read the inode.  */
	status = ext2fs_devread (blkno << LOG2_EXT2_BLOCK_SIZE (data), blkoff,
				 sizeof (struct ext2_inode), (char *) inode);
	if (status == 0) {
		return (0);
	}

	return (1);
}


void ext2fs_free_node (ext2fs_node_t node, ext2fs_node_t currroot) {
	if ((node != &ext2fs_root->diropen) && (node != currroot)) {
		free (node);
	}
}


static int ext2fs_read_block (ext2fs_node_t node, int fileblock) {
	struct ext2_data *data = node->data;
	struct ext2_inode *inode = &node->inode;
	int blknr;
	int blksz = EXT2_BLOCK_SIZE (data);
	int log2_blksz = LOG2_EXT2_BLOCK_SIZE (data);
	int status;

	/* Direct blocks.  */
	if (fileblock < INDIRECT_BLOCKS) {
		blknr = __le32_to_cpu (inode->b.blocks.dir_blocks[fileblock]);
	}
	/* Indirect.  */
	else if (fileblock < (INDIRECT_BLOCKS + (blksz / 4))) {
		if (indir1_block == NULL) {
			indir1_block = (uint32_t *) memalign(ARCH_DMA_MINALIGN,
							     blksz);
			if (indir1_block == NULL) {
				printf ("** ext2fs read block (indir 1) malloc failed. **\n");
				return (-1);
			}
			indir1_size = blksz;
			indir1_blkno = -1;
		}
		if (blksz != indir1_size) {
			free (indir1_block);
			indir1_block = NULL;
			indir1_size = 0;
			indir1_blkno = -1;
			indir1_block = (uint32_t *) memalign(ARCH_DMA_MINALIGN,
							     blksz);
			if (indir1_block == NULL) {
				printf ("** ext2fs read block (indir 1) malloc failed. **\n");
				return (-1);
			}
			indir1_size = blksz;
		}
		if ((__le32_to_cpu (inode->b.blocks.indir_block) <<
		     log2_blksz) != indir1_blkno) {
			status = ext2fs_devread (__le32_to_cpu(inode->b.blocks.indir_block) << log2_blksz,
						 0, blksz,
						 (char *) indir1_block);
			if (status == 0) {
				printf ("** ext2fs read block (indir 1) failed. **\n");
				return (0);
			}
			indir1_blkno =
				__le32_to_cpu (inode->b.blocks.
					       indir_block) << log2_blksz;
		}
		blknr = __le32_to_cpu (indir1_block
				       [fileblock - INDIRECT_BLOCKS]);
	}
	/* Double indirect.  */
	else if (fileblock <
		 (INDIRECT_BLOCKS + (blksz / 4 * (blksz / 4 + 1)))) {
		unsigned int perblock = blksz / 4;
		unsigned int rblock = fileblock - (INDIRECT_BLOCKS
						   + blksz / 4);

		if (indir1_block == NULL) {
			indir1_block = (uint32_t *) memalign(ARCH_DMA_MINALIGN,
							     blksz);
			if (indir1_block == NULL) {
				printf ("** ext2fs read block (indir 2 1) malloc failed. **\n");
				return (-1);
			}
			indir1_size = blksz;
			indir1_blkno = -1;
		}
		if (blksz != indir1_size) {
			free (indir1_block);
			indir1_block = NULL;
			indir1_size = 0;
			indir1_blkno = -1;
			indir1_block = (uint32_t *) memalign(ARCH_DMA_MINALIGN,
							     blksz);
			if (indir1_block == NULL) {
				printf ("** ext2fs read block (indir 2 1) malloc failed. **\n");
				return (-1);
			}
			indir1_size = blksz;
		}
		if ((__le32_to_cpu (inode->b.blocks.double_indir_block) <<
		     log2_blksz) != indir1_blkno) {
			status = ext2fs_devread (__le32_to_cpu(inode->b.blocks.double_indir_block) << log2_blksz,
						0, blksz,
						(char *) indir1_block);
			if (status == 0) {
				printf ("** ext2fs read block (indir 2 1) failed. **\n");
				return (-1);
			}
			indir1_blkno =
				__le32_to_cpu (inode->b.blocks.double_indir_block) << log2_blksz;
		}

		if (indir2_block == NULL) {
			indir2_block = (uint32_t *) memalign(ARCH_DMA_MINALIGN,
							     blksz);
			if (indir2_block == NULL) {
				printf ("** ext2fs read block (indir 2 2) malloc failed. **\n");
				return (-1);
			}
			indir2_size = blksz;
			indir2_blkno = -1;
		}
		if (blksz != indir2_size) {
			free (indir2_block);
			indir2_block = NULL;
			indir2_size = 0;
			indir2_blkno = -1;
			indir2_block = (uint32_t *) memalign(ARCH_DMA_MINALIGN,
							     blksz);
			if (indir2_block == NULL) {
				printf ("** ext2fs read block (indir 2 2) malloc failed. **\n");
				return (-1);
			}
			indir2_size = blksz;
		}
		if ((__le32_to_cpu (indir1_block[rblock / perblock]) <<
		     log2_blksz) != indir2_blkno) {
			status = ext2fs_devread (__le32_to_cpu(indir1_block[rblock / perblock]) << log2_blksz,
						 0, blksz,
						 (char *) indir2_block);
			if (status == 0) {
				printf ("** ext2fs read block (indir 2 2) failed. **\n");
				return (-1);
			}
			indir2_blkno =
				__le32_to_cpu (indir1_block[rblock / perblock]) << log2_blksz;
		}
		blknr = __le32_to_cpu (indir2_block[rblock % perblock]);
	}
	/* Tripple indirect.  */
	else {
		printf ("** ext2fs doesn't support tripple indirect blocks. **\n");
		return (-1);
	}
#ifdef DEBUG
	printf ("ext2fs_read_block %08x\n", blknr);
#endif
	return (blknr);
}


int ext2fs_read_file
	(ext2fs_node_t node, int pos, unsigned int len, char *buf) {
	int i;
	int blockcnt;
	int log2blocksize = LOG2_EXT2_BLOCK_SIZE (node->data);
	int blocksize = 1 << (log2blocksize + DISK_SECTOR_BITS);
	unsigned int filesize = __le32_to_cpu(node->inode.size);

	/* Adjust len so it we can't read past the end of the file.  */
	if (len > filesize) {
		len = filesize;
	}
	blockcnt = ((len + pos) + blocksize - 1) / blocksize;

	for (i = pos / blocksize; i < blockcnt; i++) {
		int blknr;
		int blockoff = pos % blocksize;
		int blockend = blocksize;

		int skipfirst = 0;

		blknr = ext2fs_read_block (node, i);
		if (blknr < 0) {
			return (-1);
		}

		/* Last block.  */
		if (i == blockcnt - 1) {
			blockend = (len + pos) % blocksize;

			/* The last portion is exactly blocksize.  */
			if (!blockend) {
				blockend = blocksize;
			}
		}

		/* First block.  */
		if (i == pos / blocksize) {
			skipfirst = blockoff;
			blockend -= skipfirst;
		}

		/* grab middle blocks in one go */
		if (i != pos / blocksize && i != blockcnt - 1 && blockcnt > 3) {
			int oldblk = blknr;
			int blocknxt;
			while (i < blockcnt - 1) {
				blocknxt = ext2fs_read_block(node, i + 1);
				if (blocknxt == (oldblk + 1)) {
					oldblk = blocknxt;
					i++;
				} else {
					blocknxt = ext2fs_read_block(node, i);
					break;
				}
			}

			if (oldblk == blknr)
				blockend = blocksize;
			else
				blockend = (1 + blocknxt - blknr) * blocksize;
		}

		blknr = blknr << log2blocksize;

		/* If the block number is 0 this block is not stored on disk but
		   is zero filled instead.  */
		if (blknr) {
			int status;

			status = ext2fs_devread (blknr, skipfirst, blockend, buf);
			if (status == 0) {
				return (-1);
			}
		} else {
			memset (buf, 0, blocksize - skipfirst);
		}
		buf += blockend - skipfirst;
	}
	return (len);
}


static int ext2fs_iterate_dir (ext2fs_node_t dir, char *name, ext2fs_node_t * fnode, int *ftype)
{
	unsigned int fpos = 0;
	int status;
	struct ext2fs_node *diro = (struct ext2fs_node *) dir;

#ifdef DEBUG
	if (name != NULL)
		printf ("Iterate dir %s\n", name);
#endif /* of DEBUG */
	if (!diro->inode_read) {
		status = ext2fs_read_inode (diro->data, diro->ino,
					    &diro->inode);
		if (status == 0) {
			return (0);
		}
	}
	/* Search the file.  */
	while (fpos < __le32_to_cpu (diro->inode.size)) {
		struct ext2_dirent dirent;

		status = ext2fs_read_file (diro, fpos,
					   sizeof (struct ext2_dirent),
					   (char *) &dirent);
		if (status < 1) {
			return (0);
		}
		if (dirent.namelen != 0) {
			char filename[dirent.namelen + 1];
			ext2fs_node_t fdiro;
			int type = FILETYPE_UNKNOWN;

			status = ext2fs_read_file (diro,
						   fpos + sizeof (struct ext2_dirent),
						   dirent.namelen, filename);
			if (status < 1) {
				return (0);
			}
			fdiro = malloc (sizeof (struct ext2fs_node));
			if (!fdiro) {
				return (0);
			}

			fdiro->data = diro->data;
			fdiro->ino = __le32_to_cpu (dirent.inode);

			filename[dirent.namelen] = '\0';

			if (dirent.filetype != FILETYPE_UNKNOWN) {
				fdiro->inode_read = 0;

				if (dirent.filetype == FILETYPE_DIRECTORY) {
					type = FILETYPE_DIRECTORY;
				} else if (dirent.filetype ==
					   FILETYPE_SYMLINK) {
					type = FILETYPE_SYMLINK;
				} else if (dirent.filetype == FILETYPE_REG) {
					type = FILETYPE_REG;
				}
			} else {
				/* The filetype can not be read from the dirent, get it from inode */

				status = ext2fs_read_inode (diro->data,
							    __le32_to_cpu(dirent.inode),
							    &fdiro->inode);
				if (status == 0) {
					free (fdiro);
					return (0);
				}
				fdiro->inode_read = 1;

				if ((__le16_to_cpu (fdiro->inode.mode) &
				     FILETYPE_INO_MASK) ==
				    FILETYPE_INO_DIRECTORY) {
					type = FILETYPE_DIRECTORY;
				} else if ((__le16_to_cpu (fdiro->inode.mode)
					    & FILETYPE_INO_MASK) ==
					   FILETYPE_INO_SYMLINK) {
					type = FILETYPE_SYMLINK;
				} else if ((__le16_to_cpu (fdiro->inode.mode)
					    & FILETYPE_INO_MASK) ==
					   FILETYPE_INO_REG) {
					type = FILETYPE_REG;
				}
			}
#ifdef DEBUG
			printf ("iterate >%s<\n", filename);
#endif /* of DEBUG */
			if ((name != NULL) && (fnode != NULL)
			    && (ftype != NULL)) {
				if (strcmp (filename, name) == 0) {
					*ftype = type;
					*fnode = fdiro;
					return (1);
				}
			} else {
				if (fdiro->inode_read == 0) {
					status = ext2fs_read_inode (diro->data,
							    __le32_to_cpu (dirent.inode),
							    &fdiro->inode);
					if (status == 0) {
						free (fdiro);
						return (0);
					}
					fdiro->inode_read = 1;
				}
				switch (type) {
				case FILETYPE_DIRECTORY:
					printf ("<DIR> ");
					break;
				case FILETYPE_SYMLINK:
					printf ("<SYM> ");
					break;
				case FILETYPE_REG:
					printf ("      ");
					break;
				default:
					printf ("< ? > ");
					break;
				}
				printf ("%10d %s\n",
					__le32_to_cpu (fdiro->inode.size),
					filename);
			}
			free (fdiro);
		}
		fpos += __le16_to_cpu (dirent.direntlen);
	}
	return (0);
}


static char *ext2fs_read_symlink (ext2fs_node_t node) {
	char *symlink;
	struct ext2fs_node *diro = node;
	int status;

	if (!diro->inode_read) {
		status = ext2fs_read_inode (diro->data, diro->ino,
					    &diro->inode);
		if (status == 0) {
			return (0);
		}
	}
	symlink = malloc (__le32_to_cpu (diro->inode.size) + 1);
	if (!symlink) {
		return (0);
	}
	/* If the filesize of the symlink is bigger than
	   60 the symlink is stored in a separate block,
	   otherwise it is stored in the inode.  */
	if (__le32_to_cpu (diro->inode.size) <= 60) {
		strncpy (symlink, diro->inode.b.symlink,
			 __le32_to_cpu (diro->inode.size));
	} else {
		status = ext2fs_read_file (diro, 0,
					   __le32_to_cpu (diro->inode.size),
					   symlink);
		if (status == 0) {
			free (symlink);
			return (0);
		}
	}
	symlink[__le32_to_cpu (diro->inode.size)] = '\0';
	return (symlink);
}


int ext2fs_find_file1
	(const char *currpath,
	 ext2fs_node_t currroot, ext2fs_node_t * currfound, int *foundtype) {
	char fpath[strlen (currpath) + 1];
	char *name = fpath;
	char *next;
	int status;
	int type = FILETYPE_DIRECTORY;
	ext2fs_node_t currnode = currroot;
	ext2fs_node_t oldnode = currroot;

	strncpy (fpath, currpath, strlen (currpath) + 1);

	/* Remove all leading slashes.  */
	while (*name == '/') {
		name++;
	}
	if (!*name) {
		*currfound = currnode;
		return (1);
	}

	for (;;) {
		int found;

		/* Extract the actual part from the pathname.  */
		next = strchr (name, '/');
		if (next) {
			/* Remove all leading slashes.  */
			while (*next == '/') {
				*(next++) = '\0';
			}
		}

		/* At this point it is expected that the current node is a directory, check if this is true.  */
		if (type != FILETYPE_DIRECTORY) {
			ext2fs_free_node (currnode, currroot);
			return (0);
		}

		oldnode = currnode;

		/* Iterate over the directory.  */
		found = ext2fs_iterate_dir (currnode, name, &currnode, &type);
		if (found == 0) {
			return (0);
		}
		if (found == -1) {
			break;
		}

		/* Read in the symlink and follow it.  */
		if (type == FILETYPE_SYMLINK) {
			char *symlink;

			/* Test if the symlink does not loop.  */
			if (++symlinknest == 8) {
				ext2fs_free_node (currnode, currroot);
				ext2fs_free_node (oldnode, currroot);
				return (0);
			}

			symlink = ext2fs_read_symlink (currnode);
			ext2fs_free_node (currnode, currroot);

			if (!symlink) {
				ext2fs_free_node (oldnode, currroot);
				return (0);
			}
#ifdef DEBUG
			printf ("Got symlink >%s<\n", symlink);
#endif /* of DEBUG */
			/* The symlink is an absolute path, go back to the root inode.  */
			if (symlink[0] == '/') {
				ext2fs_free_node (oldnode, currroot);
				oldnode = &ext2fs_root->diropen;
			}

			/* Lookup the node the symlink points to.  */
			status = ext2fs_find_file1 (symlink, oldnode,
						    &currnode, &type);

			free (symlink);

			if (status == 0) {
				ext2fs_free_node (oldnode, currroot);
				return (0);
			}
		}

		ext2fs_free_node (oldnode, currroot);

		/* Found the node!  */
		if (!next || *next == '\0') {
			*currfound = currnode;
			*foundtype = type;
			return (1);
		}
		name = next;
	}
	return (-1);
}


int ext2fs_find_file
	(const char *path,
	 ext2fs_node_t rootnode, ext2fs_node_t * foundnode, int expecttype) {
	int status;
	int foundtype = FILETYPE_DIRECTORY;


	symlinknest = 0;
	if (!path) {
		return (0);
	}

	status = ext2fs_find_file1 (path, rootnode, foundnode, &foundtype);
	if (status == 0) {
		return (0);
	}
	/* Check if the node that was found was of the expected type.  */
	if ((expecttype == FILETYPE_REG) && (foundtype != expecttype)) {
		return (0);
	} else if ((expecttype == FILETYPE_DIRECTORY)
		   && (foundtype != expecttype)) {
		return (0);
	}
	return (1);
}


int ext2fs_ls (const char *dirname) {
	ext2fs_node_t dirnode;
	int status;

	if (ext2fs_root == NULL) {
		return (0);
	}

	status = ext2fs_find_file (dirname, &ext2fs_root->diropen, &dirnode,
				   FILETYPE_DIRECTORY);
	if (status != 1) {
		printf ("** Can not find directory. **\n");
		return (1);
	}
	ext2fs_iterate_dir (dirnode, NULL, NULL, NULL);
	ext2fs_free_node (dirnode, &ext2fs_root->diropen);
	return (0);
}


int ext2fs_open (const char *filename) {
	ext2fs_node_t fdiro = NULL;
	int status;
	int len;

	if (ext2fs_root == NULL) {
		return (-1);
	}
	ext2fs_file = NULL;
	status = ext2fs_find_file (filename, &ext2fs_root->diropen, &fdiro,
				   FILETYPE_REG);
	if (status == 0) {
		goto fail;
	}
	if (!fdiro->inode_read) {
		status = ext2fs_read_inode (fdiro->data, fdiro->ino,
					    &fdiro->inode);
		if (status == 0) {
			goto fail;
		}
	}
	len = __le32_to_cpu (fdiro->inode.size);
	ext2fs_file = fdiro;
	return (len);

fail:
	ext2fs_free_node (fdiro, &ext2fs_root->diropen);
	return (-1);
}


int ext2fs_close (void
	) {
	if ((ext2fs_file != NULL) && (ext2fs_root != NULL)) {
		ext2fs_free_node (ext2fs_file, &ext2fs_root->diropen);
		ext2fs_file = NULL;
	}
	if (ext2fs_root != NULL) {
		free (ext2fs_root);
		ext2fs_root = NULL;
	}
	if (indir1_block != NULL) {
		free (indir1_block);
		indir1_block = NULL;
		indir1_size = 0;
		indir1_blkno = -1;
	}
	if (indir2_block != NULL) {
		free (indir2_block);
		indir2_block = NULL;
		indir2_size = 0;
		indir2_blkno = -1;
	}
	return (0);
}


int ext2fs_read (char *buf, unsigned len) {
	int status;

	if (ext2fs_root == NULL) {
		return (0);
	}

	if (ext2fs_file == NULL) {
		return (0);
	}

	status = ext2fs_read_file (ext2fs_file, 0, len, buf);
	return (status);
}


int ext2fs_mount (unsigned part_length) {
	struct ext2_data *data;
	int status;

	data = malloc (sizeof (struct ext2_data));
	if (!data) {
		return (0);
	}
	/* Read the superblock.  */
	status = ext2fs_devread (1 * 2, 0, sizeof (struct ext2_sblock),
				 (char *) &data->sblock);
	if (status == 0) {
		goto fail;
	}
	/* Make sure this is an ext2 filesystem.  */
	if (__le16_to_cpu (data->sblock.magic) != EXT2_MAGIC) {
		goto fail;
	}
	if (__le32_to_cpu(data->sblock.revision_level == 0)) {
		inode_size = 128;
	} else {
		inode_size = __le16_to_cpu(data->sblock.inode_size);
	}
#ifdef DEBUG
	printf("EXT2 rev %d, inode_size %d\n",
			__le32_to_cpu(data->sblock.revision_level), inode_size);
#endif
	data->diropen.data = data;
	data->diropen.ino = 2;
	data->diropen.inode_read = 1;
	data->inode = &data->diropen.inode;

	status = ext2fs_read_inode (data, 2, data->inode);
	if (status == 0) {
		goto fail;
	}

	ext2fs_root = data;

	return (1);

fail:
	printf ("Failed to mount ext2 filesystem...\n");
	free (data);
	ext2fs_root = NULL;
	return (0);
}