Add ext2fs support to the loader.

1 files changed, 903 insertions, 0 deletions

diff --git a/lib/libstand/ext2fs.c b/lib/libstand/ext2fs.c
new file mode 100644
index 0000000..1303255
--- /dev/null
+++ b/lib/libstand/ext2fs.c
@@ -0,0 +1,903 @@
+/*-
+ * Copyright (c) 1999,2000 Jonathan Lemon <jlemon@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	$FreeBSD$
+ */
+/*-
+ * Copyright (c) 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * The Mach Operating System project at Carnegie-Mellon University.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *  
+ *
+ * Copyright (c) 1990, 1991 Carnegie Mellon University
+ * All Rights Reserved.
+ *
+ * Author: David Golub
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+
+#include <sys/param.h>
+#include <sys/time.h>
+#include "stand.h"
+#include "string.h"
+
+static int	ext2fs_open(const char *path, struct open_file *f);
+static int	ext2fs_close(struct open_file *f);
+static int	ext2fs_read(struct open_file *f, void *buf,
+			 size_t size, size_t *resid);
+static off_t	ext2fs_seek(struct open_file *f, off_t offset, int where);
+static int	ext2fs_stat(struct open_file *f, struct stat *sb);
+static int	ext2fs_readdir(struct open_file *f, struct dirent *d);
+
+static int dtmap[] = { DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR,
+			 DT_BLK, DT_FIFO, DT_SOCK, DT_LNK };
+#define EXTFTODT(x)	(x) > sizeof(dtmap) / sizeof(dtmap[0]) ? \
+			DT_UNKNOWN : dtmap[x]
+
+struct fs_ops ext2fs_fsops = {
+	"ext2fs",
+	ext2fs_open,
+	ext2fs_close,
+	ext2fs_read,
+	null_write,
+	ext2fs_seek,
+	ext2fs_stat,
+	ext2fs_readdir
+};
+
+#define	EXT2_SBSIZE	1024
+#define	EXT2_SBLOCK	(1024 / DEV_BSIZE)	/* block offset of superblock */
+#define EXT2_MAGIC	0xef53
+#define EXT2_ROOTINO	2
+
+#define EXT2_REV0		0	/* original revision of ext2 */
+#define EXT2_R0_ISIZE		128	/* inode size */
+#define EXT2_R0_FIRSTINO	11	/* first inode */
+
+#define EXT2_MINBSHIFT		10	/* mininum block shift */
+#define EXT2_MINFSHIFT		10	/* mininum frag shift */
+
+#define NDADDR		12		/* # of direct blocks */
+#define NIADDR		3		/* # of indirect blocks */
+
+/*
+ * file system block to disk address
+ */
+#define fsb_to_db(fs, blk)	((blk) << (fs)->fs_fsbtodb)
+
+/*
+ * inode to block group offset
+ * inode to block group
+ * inode to disk address
+ * inode to block offset
+ */
+#define ino_to_bgo(fs, ino)	(((ino) - 1) % (fs)->fs_ipg)
+#define ino_to_bg(fs, ino)	(((ino) - 1) / (fs)->fs_ipg)
+#define ino_to_db(fs, bg, ino) \
+	fsb_to_db(fs, ((bg)[ino_to_bg(fs, ino)].bg_inotbl + \
+	    ino_to_bgo(fs, ino) / (fs)->fs_ipb))
+#define ino_to_bo(fs, ino)	(ino_to_bgo(fs, ino) % (fs)->fs_ipb)
+
+#define nindir(fs) \
+	((fs)->fs_bsize / sizeof(u_int32_t))
+#define lblkno(fs, loc)				/* loc / bsize */ \
+	((loc) >> (fs)->fs_bshift)
+#define smalllblktosize(fs, blk)		/* blk * bsize */ \
+	((blk) << (fs)->fs_bshift)
+#define blkoff(fs, loc)				/* loc % bsize */ \
+	((loc) & (fs)->fs_bmask)
+#define fragroundup(fs, size)			/* roundup(size, fsize) */ \
+	(((size) + (fs)->fs_fmask) & ~(fs)->fs_fmask)
+#define dblksize(fs, dip, lbn) \
+	(((lbn) >= NDADDR || (dip)->di_size >= smalllblktosize(fs, (lbn) + 1)) \
+	    ? (fs)->fs_bsize \
+	    : (fragroundup(fs, blkoff(fs, (dip)->di_size))))
+
+/*
+ * superblock describing ext2fs
+ */
+struct ext2fs_disk {
+	u_int32_t	fd_inodes;	/* # of inodes */
+	u_int32_t	fd_blocks;	/* # of blocks */
+	u_int32_t	fd_resblk;	/* # of reserved blocks */
+	u_int32_t	fd_freeblk;	/* # of free blocks */
+	u_int32_t	fd_freeino;	/* # of free inodes */
+	u_int32_t	fd_firstblk;	/* first data block */
+	u_int32_t	fd_bsize;	/* block size */
+	u_int32_t	fd_fsize;	/* frag size */
+	u_int32_t	fd_bpg;		/* blocks per group */
+	u_int32_t	fd_fpg;		/* frags per group */
+	u_int32_t	fd_ipg;		/* inodes per group */
+	u_int32_t	fd_mtime;	/* mount time */
+	u_int32_t	fd_wtime;	/* write time */
+	u_int16_t	fd_mount;	/* # of mounts */
+	int16_t		fd_maxmount;	/* max # of mounts */
+	u_int16_t	fd_magic;	/* magic number */
+	u_int16_t	fd_state;	/* state */
+	u_int16_t	fd_eflag;	/* error flags */
+	u_int16_t	fd_mnrrev;	/* minor revision */
+	u_int32_t	fd_lastchk;	/* last check */
+	u_int32_t	fd_chkintvl;	/* maximum check interval */
+	u_int32_t	fd_os;		/* os */
+	u_int32_t	fd_revision;	/* revision */
+	u_int16_t	fd_uid;		/* uid for reserved blocks */
+	u_int16_t	fd_gid;		/* gid for reserved blocks */
+
+	u_int32_t	fd_firstino;	/* first non-reserved inode */
+	u_int16_t	fd_isize;	/* inode size */
+	u_int16_t	fd_nblkgrp;	/* block group # of superblock */
+	u_int32_t	fd_fcompat;	/* compatible features */
+	u_int32_t	fd_fincompat;	/* incompatible features */
+	u_int32_t	fd_frocompat;	/* read-only compatabilties */
+	u_int8_t	fd_uuid[16];	/* volume uuid */
+	char 		fd_volname[16];	/* volume name */
+	char 		fd_fsmnt[64];	/* name last mounted on */
+	u_int32_t	fd_bitmap;	/* compression bitmap */
+
+	u_int8_t	fd_nblkpa;	/* # of blocks to preallocate */	
+	u_int8_t	fd_ndblkpa;	/* # of dir blocks to preallocate */
+};
+
+struct ext2fs_core {
+	int		fc_bsize;	/* block size */
+	int		fc_bshift;	/* block shift amount */
+	int		fc_bmask;	/* block mask */
+	int		fc_fsize;	/* frag size */
+	int		fc_fshift;	/* frag shift amount */
+	int		fc_fmask;	/* frag mask */
+	int		fc_isize;	/* inode size */
+	int		fc_imask;	/* inode mask */
+	int		fc_firstino;	/* first non-reserved inode */
+	int		fc_ipb;		/* inodes per block */
+	int		fc_fsbtodb;	/* fsb to ds shift */
+};
+
+struct ext2fs {
+	struct		ext2fs_disk fs_fd;
+	char		fs_pad[EXT2_SBSIZE - sizeof(struct ext2fs_disk)];
+	struct		ext2fs_core fs_fc;
+
+#define fs_magic	fs_fd.fd_magic
+#define fs_revision	fs_fd.fd_revision
+#define fs_blocks	fs_fd.fd_blocks
+#define fs_firstblk	fs_fd.fd_firstblk
+#define fs_bpg		fs_fd.fd_bpg
+#define fs_ipg		fs_fd.fd_ipg
+	    
+#define fs_bsize	fs_fc.fc_bsize
+#define fs_bshift	fs_fc.fc_bshift
+#define fs_bmask	fs_fc.fc_bmask
+#define fs_fsize	fs_fc.fc_fsize
+#define fs_fshift	fs_fc.fc_fshift
+#define fs_fmask	fs_fc.fc_fmask
+#define fs_isize	fs_fc.fc_isize
+#define fs_imask	fs_fc.fc_imask
+#define fs_firstino	fs_fc.fc_firstino
+#define fs_ipb		fs_fc.fc_ipb
+#define fs_fsbtodb	fs_fc.fc_fsbtodb
+};
+
+struct ext2blkgrp {
+	u_int32_t	bg_blkmap;	/* block bitmap */
+	u_int32_t	bg_inomap;	/* inode bitmap */
+	u_int32_t	bg_inotbl;	/* inode table */
+	u_int16_t	bg_nfblk;	/* # of free blocks */
+	u_int16_t	bg_nfino;	/* # of free inodes */
+	u_int16_t	bg_ndirs;	/* # of dirs */
+	char		bg_pad[14];
+};
+
+struct ext2dinode {
+	u_int16_t	di_mode;	/* mode */
+	u_int16_t	di_uid;		/* uid */
+	u_int32_t	di_size;	/* byte size */
+	u_int32_t	di_atime;	/* access time */
+	u_int32_t	di_ctime;	/* creation time */
+	u_int32_t	di_mtime;	/* modification time */
+	u_int32_t	di_dtime;	/* deletion time */
+	u_int16_t	di_gid;		/* gid */
+	u_int16_t	di_nlink;	/* link count */
+	u_int32_t	di_nblk;	/* block count */
+	u_int32_t	di_flags;	/* file flags */
+
+	u_int32_t	di_osdep1;	/* os dependent stuff */
+
+	u_int32_t	di_db[NDADDR];	/* direct blocks */
+	u_int32_t	di_ib[NIADDR];	/* indirect blocks */
+	u_int32_t	di_version;	/* version */
+	u_int32_t	di_facl;	/* file acl */
+	u_int32_t	di_dacl;	/* dir acl */
+	u_int32_t	di_faddr;	/* fragment addr */
+
+	u_int8_t	di_frag;	/* fragment number */
+	u_int8_t	di_fsize;	/* fragment size */
+
+	char		di_pad[10];
+
+#define di_shortlink	di_db
+};
+
+#define EXT2_MAXNAMLEN       255
+
+struct ext2dirent {
+	u_int32_t	d_ino;		/* inode */
+	u_int16_t	d_reclen;	/* directory entry length */
+	u_int8_t	d_namlen;	/* name length */
+	u_int8_t	d_type;		/* file type */
+	char		d_name[EXT2_MAXNAMLEN];
+};
+
+struct file {
+	off_t		f_seekp;		/* seek pointer */
+	struct 		ext2fs *f_fs;		/* pointer to super-block */
+	struct 		ext2blkgrp *f_bg;	/* pointer to blkgrp map */
+	struct 		ext2dinode f_di;	/* copy of on-disk inode */
+	int		f_nindir[NIADDR];	/* number of blocks mapped by
+						   indirect block at level i */
+	char		*f_blk[NIADDR];		/* buffer for indirect block
+						   at level i */
+	size_t		f_blksize[NIADDR];	/* size of buffer */
+	daddr_t		f_blkno[NIADDR];	/* disk address of block in
+						   buffer */
+	char		*f_buf;			/* buffer for data block */
+	size_t		f_buf_size;		/* size of data block */
+	daddr_t		f_buf_blkno;		/* block number of data block */
+};
+
+/* forward decls */
+static int 	read_inode(ino_t inumber, struct open_file *f);
+static int	block_map(struct open_file *f, daddr_t file_block,
+		    daddr_t *disk_block_p);
+static int	buf_read_file(struct open_file *f, char **buf_p,
+		    size_t *size_p);
+static int	search_directory(char *name, struct open_file *f,
+		    ino_t *inumber_p);
+
+/*
+ * Open a file.
+ */
+static int
+ext2fs_open(const char *upath, struct open_file *f)
+{
+	struct file *fp;
+	struct ext2fs *fs;
+	size_t buf_size;
+	ino_t inumber, parent_inumber;
+	int i, len, groups, bg_per_blk, blkgrps, mult;
+	int nlinks = 0;
+	int error = 0;
+	char *cp, *ncp, *path = NULL, *buf = NULL;
+	char namebuf[MAXPATHLEN+1];
+	char c;
+
+	/* allocate file system specific data structure */
+	fp = malloc(sizeof(struct file));
+	if (fp == NULL)
+		return (ENOMEM);
+	bzero(fp, sizeof(struct file));
+	f->f_fsdata = (void *)fp;
+
+	/* allocate space and read super block */
+	fs = (struct ext2fs *)malloc(sizeof(*fs));
+	fp->f_fs = fs;
+	twiddle();
+	error = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
+	    EXT2_SBLOCK, EXT2_SBSIZE, (char *)fs, &buf_size);
+	if (error)
+		goto out;
+
+	if (buf_size != EXT2_SBSIZE || fs->fs_magic != EXT2_MAGIC) {
+		error = EINVAL;
+		goto out;
+	}
+
+	/*
+	 * compute in-core values for the superblock
+	 */
+	fs->fs_bshift = EXT2_MINBSHIFT + fs->fs_fd.fd_bsize;
+	fs->fs_bsize = 1 << fs->fs_bshift;
+	fs->fs_bmask = fs->fs_bsize - 1;
+
+	fs->fs_fshift = EXT2_MINFSHIFT + fs->fs_fd.fd_fsize;
+	fs->fs_fsize = 1 << fs->fs_fshift;
+	fs->fs_fmask = fs->fs_fsize - 1;
+
+	if (fs->fs_revision == EXT2_REV0) {
+		fs->fs_isize = EXT2_R0_ISIZE;
+		fs->fs_firstino = EXT2_R0_FIRSTINO;
+	} else {
+		fs->fs_isize = fs->fs_fd.fd_isize;
+		fs->fs_firstino = fs->fs_fd.fd_firstino;
+	}
+	fs->fs_imask = fs->fs_isize - 1;
+	fs->fs_ipb = fs->fs_bsize / fs->fs_isize;
+	fs->fs_fsbtodb = (fs->fs_bsize / DEV_BSIZE) - 1;
+
+	/*
+	 * we have to load in the "group descriptors" here
+	 */
+	groups = howmany(fs->fs_blocks - fs->fs_firstblk, fs->fs_bpg);
+	bg_per_blk = fs->fs_bsize / sizeof(struct ext2blkgrp);
+	blkgrps = howmany(groups, bg_per_blk);
+	len = blkgrps * fs->fs_bsize;
+
+	fp->f_bg = malloc(len);
+	twiddle();
+	error = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
+	    EXT2_SBLOCK + EXT2_SBSIZE / DEV_BSIZE, len,
+	    (char *)fp->f_bg, &buf_size);
+	if (error)
+		goto out;
+
+	/*
+	 * XXX
+	 * validation of values?  (blocksize, descriptors, etc?)
+	 */
+
+	/*
+	 * Calculate indirect block levels.
+	 */
+	mult = 1;
+	for (i = 0; i < NIADDR; i++) {
+		mult *= nindir(fs);
+		fp->f_nindir[i] = mult;
+	}
+
+	inumber = EXT2_ROOTINO;
+	if ((error = read_inode(inumber, f)) != 0)
+		goto out;
+
+	path = strdup(upath);
+	if (path == NULL) {
+		error = ENOMEM;
+		goto out;
+	}
+	cp = path;
+	while (*cp) {
+		/*
+		 * Remove extra separators
+		 */
+		while (*cp == '/')
+			cp++;
+		if (*cp == '\0')
+			break;
+
+		/*
+		 * Check that current node is a directory.
+		 */
+		if (! S_ISDIR(fp->f_di.di_mode)) {
+			error = ENOTDIR;
+			goto out;
+		}
+
+		/*
+		 * Get next component of path name.
+		 */
+		len = 0;
+
+		ncp = cp;
+		while ((c = *cp) != '\0' && c != '/') {
+			if (++len > EXT2_MAXNAMLEN) {
+				error = ENOENT;
+				goto out;
+			}
+			cp++;
+		}
+		*cp = '\0';
+
+		/*
+		 * Look up component in current directory.
+		 * Save directory inumber in case we find a
+		 * symbolic link.
+		 */
+		parent_inumber = inumber;
+		error = search_directory(ncp, f, &inumber);
+		*cp = c;
+		if (error)
+			goto out;
+
+		/*
+		 * Open next component.
+		 */
+		if ((error = read_inode(inumber, f)) != 0)
+			goto out;
+
+		/*
+		 * Check for symbolic link.
+		 */
+		if (S_ISLNK(fp->f_di.di_mode)) {
+			int link_len = fp->f_di.di_size;
+			int len;
+
+			len = strlen(cp);
+			if (link_len + len > MAXPATHLEN ||
+			    ++nlinks > MAXSYMLINKS) {
+				error = ENOENT;
+				goto out;
+			}
+
+			bcopy(cp, &namebuf[link_len], len + 1);
+			if (fp->f_di.di_nblk == 0) {
+				bcopy(fp->f_di.di_shortlink,
+				    namebuf, link_len);
+			} else {
+				/*
+				 * Read file for symbolic link
+				 */
+				struct ext2fs *fs = fp->f_fs;
+				daddr_t	disk_block;
+				size_t buf_size;
+
+				if (! buf)
+					buf = malloc(fs->fs_bsize);
+				error = block_map(f, (daddr_t)0, &disk_block);
+				if (error)
+					goto out;
+				
+				twiddle();
+				error = (f->f_dev->dv_strategy)(f->f_devdata,
+				    F_READ, fsb_to_db(fs, disk_block),
+				    fs->fs_bsize, buf, &buf_size);
+				if (error)
+					goto out;
+
+				bcopy((char *)buf, namebuf, link_len);
+			}
+
+			/*
+			 * If relative pathname, restart at parent directory.
+			 * If absolute pathname, restart at root.
+			 */
+			cp = namebuf;
+			if (*cp != '/')
+				inumber = parent_inumber;
+			else
+				inumber = (ino_t)EXT2_ROOTINO;
+
+			if ((error = read_inode(inumber, f)) != 0)
+				goto out;
+		}
+	}
+
+	/*
+	 * Found terminal component.
+	 */
+	error = 0;
+out:
+	if (buf)
+		free(buf);
+	if (path)
+		free(path);
+	if (error) {
+		if (fp->f_buf)
+			free(fp->f_buf);
+		free(fp->f_fs);
+		free(fp);
+	}
+	return (error);
+}
+
+/*
+ * Read a new inode into a file structure.
+ */
+static int
+read_inode(ino_t inumber, struct open_file *f)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	struct ext2fs *fs = fp->f_fs;
+	struct ext2dinode *dp;
+	char *buf;
+	size_t rsize;
+	int level, error = 0;
+
+	/*
+	 * Read inode and save it.
+	 */
+	buf = malloc(fs->fs_bsize);
+	twiddle();
+	error = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
+	    ino_to_db(fs, fp->f_bg, inumber), fs->fs_bsize, buf, &rsize);
+	if (error)
+		goto out;
+	if (rsize != fs->fs_bsize) {
+		error = EIO;
+		goto out;
+	}
+
+	dp = (struct ext2dinode *)buf;
+	fp->f_di = dp[ino_to_bo(fs, inumber)];
+
+	/* clear out old buffers */
+	for (level = 0; level < NIADDR; level++)
+		fp->f_blkno[level] = -1;
+	fp->f_buf_blkno = -1;
+
+out:
+	free(buf);
+	return (error);	 
+}
+
+/*
+ * Given an offset in a file, find the disk block number that
+ * contains that block.
+ */
+static int
+block_map(struct open_file *f, daddr_t file_block, daddr_t *disk_block_p)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	struct ext2fs *fs = fp->f_fs;
+	daddr_t ind_block_num;
+	daddr_t *ind_p;
+	int idx, level;
+	int error;
+
+	/*
+	 * Index structure of an inode:
+	 *
+	 * di_db[0..NDADDR-1]	hold block numbers for blocks
+	 *			0..NDADDR-1
+	 *
+	 * di_ib[0]		index block 0 is the single indirect block
+	 *			holds block numbers for blocks
+	 *			NDADDR .. NDADDR + NINDIR(fs)-1
+	 *
+	 * di_ib[1]		index block 1 is the double indirect block
+	 *			holds block numbers for INDEX blocks for blocks
+	 *			NDADDR + NINDIR(fs) ..
+	 *			NDADDR + NINDIR(fs) + NINDIR(fs)**2 - 1
+	 *
+	 * di_ib[2]		index block 2 is the triple indirect block
+	 *			holds block numbers for double-indirect
+	 *			blocks for blocks
+	 *			NDADDR + NINDIR(fs) + NINDIR(fs)**2 ..
+	 *			NDADDR + NINDIR(fs) + NINDIR(fs)**2
+	 *				+ NINDIR(fs)**3 - 1
+	 */
+
+	if (file_block < NDADDR) {
+		/* Direct block. */
+		*disk_block_p = fp->f_di.di_db[file_block];
+		return (0);
+	}
+
+	file_block -= NDADDR;
+
+	/*
+	 * nindir[0] = NINDIR
+	 * nindir[1] = NINDIR**2
+	 * nindir[2] = NINDIR**3
+	 *	etc
+	 */
+	for (level = 0; level < NIADDR; level++) {
+		if (file_block < fp->f_nindir[level])
+			break;
+		file_block -= fp->f_nindir[level];
+	}
+	if (level == NIADDR) {
+		/* Block number too high */
+		return (EFBIG);
+	}
+
+	ind_block_num = fp->f_di.di_ib[level];
+
+	for (; level >= 0; level--) {
+		if (ind_block_num == 0) {
+			*disk_block_p = 0;	/* missing */
+			return (0);
+		}
+
+		if (fp->f_blkno[level] != ind_block_num) {
+			if (fp->f_blk[level] == (char *)0)
+				fp->f_blk[level] =
+					malloc(fs->fs_bsize);
+			twiddle();
+			error = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
+			    fsb_to_db(fp->f_fs, ind_block_num), fs->fs_bsize,
+			    fp->f_blk[level], &fp->f_blksize[level]);
+			if (error)
+				return (error);
+			if (fp->f_blksize[level] != fs->fs_bsize)
+				return (EIO);
+			fp->f_blkno[level] = ind_block_num;
+		}
+
+		ind_p = (daddr_t *)fp->f_blk[level];
+
+		if (level > 0) {
+			idx = file_block / fp->f_nindir[level - 1];
+			file_block %= fp->f_nindir[level - 1];
+		} else {
+			idx = file_block;
+		}
+		ind_block_num = ind_p[idx];
+	}
+
+	*disk_block_p = ind_block_num;
+
+	return (0);
+}
+
+/*
+ * Read a portion of a file into an internal buffer.  Return
+ * the location in the buffer and the amount in the buffer.
+ */
+static int
+buf_read_file(struct open_file *f, char **buf_p, size_t *size_p)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	struct ext2fs *fs = fp->f_fs;
+	long off;
+	daddr_t file_block;
+	daddr_t	disk_block;
+	size_t block_size;
+	int error = 0;
+
+	off = blkoff(fs, fp->f_seekp);
+	file_block = lblkno(fs, fp->f_seekp);
+	block_size = dblksize(fs, &fp->f_di, file_block);
+
+	if (file_block != fp->f_buf_blkno) {
+		error = block_map(f, file_block, &disk_block);
+		if (error)
+			goto done;
+
+		if (fp->f_buf == (char *)0)
+			fp->f_buf = malloc(fs->fs_bsize);
+
+		if (disk_block == 0) {
+			bzero(fp->f_buf, block_size);
+			fp->f_buf_size = block_size;
+		} else {
+			twiddle();
+			error = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
+			    fsb_to_db(fs, disk_block), block_size,
+			    fp->f_buf, &fp->f_buf_size);
+			if (error)
+				goto done;
+		}
+		fp->f_buf_blkno = file_block;
+	}
+
+	/*
+	 * Return address of byte in buffer corresponding to
+	 * offset, and size of remainder of buffer after that
+	 * byte.
+	 */
+	*buf_p = fp->f_buf + off;
+	*size_p = block_size - off;
+
+	/*
+	 * But truncate buffer at end of file.
+	 */
+	if (*size_p > fp->f_di.di_size - fp->f_seekp)
+		*size_p = fp->f_di.di_size - fp->f_seekp;
+done:
+	return (error);
+}
+
+/*
+ * Search a directory for a name and return its
+ * i_number.
+ */
+static int
+search_directory(char *name, struct open_file *f, ino_t *inumber_p)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	struct ext2dirent *dp, *edp;
+	char *buf;
+	size_t buf_size;
+	int namlen, length;
+	int error;
+
+	length = strlen(name);
+	fp->f_seekp = 0;
+	while (fp->f_seekp < fp->f_di.di_size) {
+		error = buf_read_file(f, &buf, &buf_size);
+		if (error)
+			return (error);
+		dp = (struct ext2dirent *)buf;
+		edp = (struct ext2dirent *)(buf + buf_size);
+		while (dp < edp) {
+			if (dp->d_ino == (ino_t)0)
+				goto next;
+			namlen = dp->d_namlen;
+			if (namlen == length &&
+			    strncmp(name, dp->d_name, length) == 0) {
+				/* found entry */
+				*inumber_p = dp->d_ino;
+				return (0);
+			}
+		next:
+			dp = (struct ext2dirent *)((char *)dp + dp->d_reclen);
+		}
+		fp->f_seekp += buf_size;
+	}
+	return (ENOENT);
+}
+
+static int
+ext2fs_close(struct open_file *f)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	int level;
+
+	f->f_fsdata = (void *)0;
+	if (fp == (struct file *)0)
+		return (0);
+
+	for (level = 0; level < NIADDR; level++) {
+		if (fp->f_blk[level])
+			free(fp->f_blk[level]);
+	}
+	if (fp->f_buf)
+		free(fp->f_buf);
+	if (fp->f_bg)
+		free(fp->f_bg);
+	free(fp->f_fs);
+	free(fp);
+	return (0);
+}
+
+static int
+ext2fs_read(struct open_file *f, void *addr, size_t size, size_t *resid)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	size_t csize, buf_size;
+	char *buf;
+	int error = 0;
+
+	while (size != 0) {
+		if (fp->f_seekp >= fp->f_di.di_size)
+			break;
+
+		error = buf_read_file(f, &buf, &buf_size);
+		if (error)
+			break;
+
+		csize = size;
+		if (csize > buf_size)
+			csize = buf_size;
+
+		bcopy(buf, addr, csize);
+
+		fp->f_seekp += csize;
+		addr += csize;
+		size -= csize;
+	}
+	if (resid)
+		*resid = size;
+	return (error);
+}
+
+static off_t
+ext2fs_seek(struct open_file *f, off_t offset, int where)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+
+	switch (where) {
+	case SEEK_SET:
+		fp->f_seekp = offset;
+		break;
+	case SEEK_CUR:
+		fp->f_seekp += offset;
+		break;
+	case SEEK_END:
+		fp->f_seekp = fp->f_di.di_size - offset;
+		break;
+	default:
+		return (-1);
+	}
+	return (fp->f_seekp);
+}
+
+static int
+ext2fs_stat(struct open_file *f, struct stat *sb)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+
+	/* only important stuff */
+	sb->st_mode = fp->f_di.di_mode;
+	sb->st_uid = fp->f_di.di_uid;
+	sb->st_gid = fp->f_di.di_gid;
+	sb->st_size = fp->f_di.di_size;
+	return (0);
+}
+
+static int
+ext2fs_readdir(struct open_file *f, struct dirent *d)
+{
+	struct file *fp = (struct file *)f->f_fsdata;
+	struct ext2dirent *ed;
+	char *buf;
+	size_t buf_size;
+	int error;
+
+	/*
+	 * assume that a directory entry will not be split across blocks
+	 */
+again:
+	if (fp->f_seekp >= fp->f_di.di_size)
+		return (ENOENT);
+	error = buf_read_file(f, &buf, &buf_size);
+	if (error)
+		return (error);
+	ed = (struct ext2dirent *)buf;
+	fp->f_seekp += ed->d_reclen;
+	if (ed->d_ino == (ino_t)0)
+		goto again;
+	d->d_type = EXTFTODT(ed->d_type);
+	strncpy(d->d_name, ed->d_name, ed->d_namlen);
+	d->d_name[ed->d_namlen] = '\0';
+	return (0);
+}