/*      $NetBSD: ufs.c,v 1.20 1998/03/01 07:15:39 ross Exp $    */

/*-
 * Copyright (c) 2002 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by Marshall
 * Kirk McKusick and Network Associates Laboratories, the Security
 * Research Division of Network Associates, Inc. under DARPA/SPAWAR
 * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
 * research program
 *
 * Copyright (c) 1982, 1989, 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. 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.
 */

/*
 *      Stand-alone file reading package.
 */

#include <sys/param.h>
#include <sys/disklabel.h>
#include <sys/time.h>
#include <ufs/ufs/dinode.h>
#include <ufs/ufs/dir.h>
#include <ufs/ffs/fs.h>
#include "stand.h"
#include "string.h"

static int      ufs_open(const char *path, struct open_file *f);
static int      ufs_write(struct open_file *f, const void *buf, size_t size,
                size_t *resid);
static int      ufs_close(struct open_file *f);
static int      ufs_read(struct open_file *f, void *buf, size_t size, size_t *resid);
static off_t    ufs_seek(struct open_file *f, off_t offset, int where);
static int      ufs_stat(struct open_file *f, struct stat *sb);
static int      ufs_readdir(struct open_file *f, struct dirent *d);
static int      ufs_mount(const char *dev, const char *path, void **data);
static int      ufs_unmount(const char *dev, void *data);

struct fs_ops ufs_fsops = {
        .fs_name = "ufs",
        .fs_flags = 0,
        .fo_open = ufs_open,
        .fo_close = ufs_close,
        .fo_read = ufs_read,
        .fo_write = ufs_write,
        .fo_seek = ufs_seek,
        .fo_stat = ufs_stat,
        .fo_readdir = ufs_readdir,
        .fo_mount = ufs_mount,
        .fo_unmount = ufs_unmount
};

/*
 * In-core open file.
 */
struct file {
        off_t           f_seekp;        /* seek pointer */
        struct fs       *f_fs;          /* pointer to super-block */
        union dinode    f_dp;           /* copy of on-disk inode */
        int             f_nindir[UFS_NIADDR];
                                        /* number of blocks mapped by
                                           indirect block at level i */
        char            *f_blk[UFS_NIADDR];     /* buffer for indirect block at
                                           level i */
        size_t          f_blksize[UFS_NIADDR];
                                        /* size of buffer */
        ufs2_daddr_t    f_blkno[UFS_NIADDR];/* disk address of block in buffer */
        ufs2_daddr_t    f_buf_blkno;    /* block number of data block */
        char            *f_buf;         /* buffer for data block */
        size_t          f_buf_size;     /* size of data block */
        int             f_inumber;      /* inumber */
};
#define DIP(fp, field) \
        ((fp)->f_fs->fs_magic == FS_UFS1_MAGIC ? \
        (fp)->f_dp.dp1.field : (fp)->f_dp.dp2.field)

typedef struct ufs_mnt {
        char                    *um_dev;
        int                     um_fd;
        STAILQ_ENTRY(ufs_mnt)   um_link;
} ufs_mnt_t;

typedef STAILQ_HEAD(ufs_mnt_list, ufs_mnt) ufs_mnt_list_t;
static ufs_mnt_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);

static int      read_inode(ino_t, struct open_file *);
static int      block_map(struct open_file *, ufs2_daddr_t, ufs2_daddr_t *);
static int      buf_read_file(struct open_file *, char **, size_t *);
static int      buf_write_file(struct open_file *, const char *, size_t *);
static int      search_directory(char *, struct open_file *, ino_t *);
static int      ufs_use_sa_read(void *, off_t, void **, int);

/* from ffs_subr.c */
int     ffs_sbget(void *devfd, struct fs **fsp, off_t sblock, int flags,
            char *filltype,
            int (*readfunc)(void *devfd, off_t loc, void **bufp, int size));
int     ffs_sbsearch(void *, struct fs **, int, char *,
            int (*)(void *, off_t, void **, int));

/*
 * 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 fs *fs = fp->f_fs;
        char *buf;
        size_t rsize;
        int rc;

        if (fs == NULL)
            panic("fs == NULL");

        /*
         * Read inode and save it.
         */
        buf = malloc(fs->fs_bsize);
        twiddle(1);
        rc = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
                fsbtodb(fs, ino_to_fsba(fs, inumber)), fs->fs_bsize,
                buf, &rsize);
        if (rc)
                goto out;
        if (rsize != fs->fs_bsize) {
                rc = EIO;
                goto out;
        }

        if (fp->f_fs->fs_magic == FS_UFS1_MAGIC)
                fp->f_dp.dp1 = ((struct ufs1_dinode *)buf)
                    [ino_to_fsbo(fs, inumber)];
        else
                fp->f_dp.dp2 = ((struct ufs2_dinode *)buf)
                    [ino_to_fsbo(fs, inumber)];

        /*
         * Clear out the old buffers
         */
        {
                int level;

                for (level = 0; level < UFS_NIADDR; level++)
                        fp->f_blkno[level] = -1;
                fp->f_buf_blkno = -1;
        }
        fp->f_seekp = 0;
        fp->f_inumber = inumber;
out:
        free(buf);
        return (rc);     
}

/*
 * Given an offset in a file, find the disk block number that
 * contains that block.
 */
static int
block_map(struct open_file *f, ufs2_daddr_t file_block,
    ufs2_daddr_t *disk_block_p)
{
        struct file *fp = (struct file *)f->f_fsdata;
        struct fs *fs = fp->f_fs;
        int level;
        int idx;
        ufs2_daddr_t ind_block_num;
        int rc;

        /*
         * Index structure of an inode:
         *
         * di_db[0..UFS_NDADDR-1] hold block numbers for blocks
         *                      0..UFS_NDADDR-1
         *
         * di_ib[0]             index block 0 is the single indirect block
         *                      holds block numbers for blocks
         *                      UFS_NDADDR .. UFS_NDADDR + NINDIR(fs)-1
         *
         * di_ib[1]             index block 1 is the double indirect block
         *                      holds block numbers for INDEX blocks for blocks
         *                      UFS_NDADDR + NINDIR(fs) ..
         *                      UFS_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
         *                      UFS_NDADDR + NINDIR(fs) + NINDIR(fs)**2 ..
         *                      UFS_NDADDR + NINDIR(fs) + NINDIR(fs)**2
         *                              + NINDIR(fs)**3 - 1
         */

        if (file_block < UFS_NDADDR) {
                /* Direct block. */
                *disk_block_p = DIP(fp, di_db[file_block]);
                return (0);
        }

        file_block -= UFS_NDADDR;

        /*
         * nindir[0] = NINDIR
         * nindir[1] = NINDIR**2
         * nindir[2] = NINDIR**3
         *      etc
         */
        for (level = 0; level < UFS_NIADDR; level++) {
                if (file_block < fp->f_nindir[level])
                        break;
                file_block -= fp->f_nindir[level];
        }
        if (level == UFS_NIADDR) {
                /* Block number too high */
                return (EFBIG);
        }

        ind_block_num = DIP(fp, 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(1);
                        rc = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
                                fsbtodb(fp->f_fs, ind_block_num),
                                fs->fs_bsize,
                                fp->f_blk[level],
                                &fp->f_blksize[level]);
                        if (rc)
                                return (rc);
                        if (fp->f_blksize[level] != fs->fs_bsize)
                                return (EIO);
                        fp->f_blkno[level] = ind_block_num;
                }

                if (level > 0) {
                        idx = file_block / fp->f_nindir[level - 1];
                        file_block %= fp->f_nindir[level - 1];
                } else
                        idx = file_block;

                if (fp->f_fs->fs_magic == FS_UFS1_MAGIC)
                        ind_block_num = ((ufs1_daddr_t *)fp->f_blk[level])[idx];
                else
                        ind_block_num = ((ufs2_daddr_t *)fp->f_blk[level])[idx];
        }

        *disk_block_p = ind_block_num;

        return (0);
}

/*
 * Write a portion of a file from an internal buffer.
 */
static int
buf_write_file(struct open_file *f, const char *buf_p, size_t *size_p)
{
        struct file *fp = (struct file *)f->f_fsdata;
        struct fs *fs = fp->f_fs;
        long off;
        ufs_lbn_t file_block;
        ufs2_daddr_t disk_block;
        size_t block_size;
        int rc;

        /*
         * Calculate the starting block address and offset.
         */
        off = blkoff(fs, fp->f_seekp);
        file_block = lblkno(fs, fp->f_seekp);
        block_size = sblksize(fs, DIP(fp, di_size), file_block);

        rc = block_map(f, file_block, &disk_block);
        if (rc)
                return (rc);

        if (disk_block == 0)
                /* Because we can't allocate space on the drive */
                return (EFBIG);

        /*
         * Truncate buffer at end of file, and at the end of
         * this block.
         */
        if (*size_p > DIP(fp, di_size) - fp->f_seekp)
                *size_p = DIP(fp, di_size) - fp->f_seekp;
        if (*size_p > block_size - off) 
                *size_p = block_size - off;

        /*
         * If we don't entirely occlude the block and it's not
         * in memory already, read it in first.
         */
        if (((off > 0) || (*size_p + off < block_size)) &&
            (file_block != fp->f_buf_blkno)) {

                if (fp->f_buf == (char *)0)
                        fp->f_buf = malloc(fs->fs_bsize);

                twiddle(4);
                rc = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
                        fsbtodb(fs, disk_block),
                        block_size, fp->f_buf, &fp->f_buf_size);
                if (rc)
                        return (rc);

                fp->f_buf_blkno = file_block;
        }

        /*
         *      Copy the user data into the cached block.
         */
        bcopy(buf_p, fp->f_buf + off, *size_p);

        /*
         *      Write the block out to storage.
         */

        twiddle(4);
        rc = (f->f_dev->dv_strategy)(f->f_devdata, F_WRITE,
                fsbtodb(fs, disk_block),
                block_size, fp->f_buf, &fp->f_buf_size);
        return (rc);
}

/*
 * 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 fs *fs = fp->f_fs;
        long off;
        ufs_lbn_t file_block;
        ufs2_daddr_t disk_block;
        size_t block_size;
        int rc;

        off = blkoff(fs, fp->f_seekp);
        file_block = lblkno(fs, fp->f_seekp);
        block_size = sblksize(fs, DIP(fp, di_size), file_block);

        if (file_block != fp->f_buf_blkno) {
                if (fp->f_buf == NULL)
                        fp->f_buf = malloc(fs->fs_bsize);

                rc = block_map(f, file_block, &disk_block);
                if (rc)
                        return (rc);

                if (disk_block == 0) {
                        bzero(fp->f_buf, block_size);
                        fp->f_buf_size = block_size;
                } else {
                        twiddle(4);
                        rc = (f->f_dev->dv_strategy)(f->f_devdata, F_READ,
                                fsbtodb(fs, disk_block),
                                block_size, fp->f_buf, &fp->f_buf_size);
                        if (rc)
                                return (rc);
                }

                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 > DIP(fp, di_size) - fp->f_seekp)
                *size_p = DIP(fp, di_size) - fp->f_seekp;

        return (0);
}

/*
 * 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 direct *dp;
        struct direct *edp;
        char *buf;
        size_t buf_size;
        int namlen, length;
        int rc;

        length = strlen(name);

        fp->f_seekp = 0;
        while (fp->f_seekp < DIP(fp, di_size)) {
                rc = buf_read_file(f, &buf, &buf_size);
                if (rc)
                        return (rc);

                dp = (struct direct *)buf;
                edp = (struct direct *)(buf + buf_size);
                while (dp < edp) {
                        if (dp->d_ino == (ino_t)0)
                                goto next;
#if BYTE_ORDER == LITTLE_ENDIAN
                        if (fp->f_fs->fs_maxsymlinklen <= 0)
                                namlen = dp->d_type;
                        else
#endif
                                namlen = dp->d_namlen;
                        if (namlen == length &&
                            !strcmp(name, dp->d_name)) {
                                /* found entry */
                                *inumber_p = dp->d_ino;
                                return (0);
                        }
                next:
                        dp = (struct direct *)((char *)dp + dp->d_reclen);
                }
                fp->f_seekp += buf_size;
        }
        return (ENOENT);
}

/*
 * Open a file.
 */
static int
ufs_open(const char *upath, struct open_file *f)
{
        char *cp, *ncp;
        int c;
        ino_t inumber, parent_inumber;
        struct file *fp;
        struct fs *fs;
        int rc;
        int nlinks = 0;
        char namebuf[MAXPATHLEN+1];
        char *buf = NULL;
        char *path = NULL;
        const char *dev;
        ufs_mnt_t *mnt;

        /* allocate file system specific data structure */
        errno = 0;
        fp = calloc(1, sizeof(struct file));
        if (fp == NULL)
                return (errno);
        f->f_fsdata = (void *)fp;

        dev = devformat((struct devdesc *)f->f_devdata);
        /* Is this device mounted? */
        STAILQ_FOREACH(mnt, &mnt_list, um_link) {
                if (strcmp(dev, mnt->um_dev) == 0)
                        break;
        }

        if (mnt == NULL) {
                /* read super block */
                twiddle(1);
                if ((rc = ffs_sbget(f, &fs, UFS_STDSB, UFS_NOHASHFAIL, "stand",
                    ufs_use_sa_read)) != 0) {
                        goto out;
                }
        } else {
                struct open_file *sbf;
                struct file *sfp;

                /* get superblock from mounted file system */
                sbf = fd2open_file(mnt->um_fd);
                sfp = sbf->f_fsdata;
                fs = sfp->f_fs;
        }
        fp->f_fs = fs;

        /*
         * Calculate indirect block levels.
         */
        {
                ufs2_daddr_t mult;
                int level;

                mult = 1;
                for (level = 0; level < UFS_NIADDR; level++) {
                        mult *= NINDIR(fs);
                        fp->f_nindir[level] = mult;
                }
        }

        inumber = UFS_ROOTINO;
        if ((rc = read_inode(inumber, f)) != 0)
                goto out;

        cp = path = strdup(upath);
        if (path == NULL) {
            rc = ENOMEM;
            goto out;
        }
        while (*cp) {

                /*
                 * Remove extra separators
                 */
                while (*cp == '/')
                        cp++;
                if (*cp == '\0')
                        break;

                /*
                 * Check that current node is a directory.
                 */
                if ((DIP(fp, di_mode) & IFMT) != IFDIR) {
                        rc = ENOTDIR;
                        goto out;
                }

                /*
                 * Get next component of path name.
                 */
                {
                        int len = 0;

                        ncp = cp;
                        while ((c = *cp) != '\0' && c != '/') {
                                if (++len > UFS_MAXNAMLEN) {
                                        rc = 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;
                rc = search_directory(ncp, f, &inumber);
                *cp = c;
                if (rc)
                        goto out;

                /*
                 * Open next component.
                 */
                if ((rc = read_inode(inumber, f)) != 0)
                        goto out;

                /*
                 * Check for symbolic link.
                 */
                if ((DIP(fp, di_mode) & IFMT) == IFLNK) {
                        int link_len = DIP(fp, di_size);
                        int len;

                        len = strlen(cp);

                        if (link_len + len > MAXPATHLEN ||
                            ++nlinks > MAXSYMLINKS) {
                                rc = ENOENT;
                                goto out;
                        }

                        bcopy(cp, &namebuf[link_len], len + 1);

                        if (link_len < fs->fs_maxsymlinklen) {
                                bcopy(DIP(fp, di_shortlink), namebuf,
                                    (unsigned) link_len);
                        } else {
                                /*
                                 * Read file for symbolic link
                                 */
                                size_t buf_size;
                                ufs2_daddr_t disk_block;
                                struct fs *fs = fp->f_fs;

                                if (!buf)
                                        buf = malloc(fs->fs_bsize);
                                rc = block_map(f, (ufs2_daddr_t)0, &disk_block);
                                if (rc)
                                        goto out;
                                
                                twiddle(1);
                                rc = (f->f_dev->dv_strategy)(f->f_devdata,
                                        F_READ, fsbtodb(fs, disk_block),
                                        fs->fs_bsize, buf, &buf_size);
                                if (rc)
                                        goto out;

                                bcopy((char *)buf, namebuf, (unsigned)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)UFS_ROOTINO;

                        if ((rc = read_inode(inumber, f)) != 0)
                                goto out;
                }
        }

        /*
         * Found terminal component.
         */
        rc = 0;
        fp->f_seekp = 0;
out:
        free(buf);
        free(path);
        if (rc) {
                free(fp->f_buf);

                if (mnt == NULL && fp->f_fs != NULL) {
                        free(fp->f_fs->fs_csp);
                        free(fp->f_fs->fs_si);
                        free(fp->f_fs);
                }
                free(fp);
        }
        return (rc);
}

/*
 * A read function for use by standalone-layer routines.
 */
static int
ufs_use_sa_read(void *devfd, off_t loc, void **bufp, int size)
{
        struct open_file *f;
        size_t buf_size;
        int error;

        f = (struct open_file *)devfd;
        if ((*bufp = malloc(size)) == NULL)
                return (ENOSPC);
        error = (f->f_dev->dv_strategy)(f->f_devdata, F_READ, loc / DEV_BSIZE,
            size, *bufp, &buf_size);
        if (error != 0)
                return (error);
        if (buf_size != size)
                return (EIO);
        return (0);
}

static int
ufs_close(struct open_file *f)
{
        ufs_mnt_t *mnt;
        struct file *fp = (struct file *)f->f_fsdata;
        int level;
        char *dev;

        f->f_fsdata = NULL;
        if (fp == NULL)
                return (0);

        for (level = 0; level < UFS_NIADDR; level++) {
                free(fp->f_blk[level]);
        }
        free(fp->f_buf);

        dev = devformat((struct devdesc *)f->f_devdata);
        STAILQ_FOREACH(mnt, &mnt_list, um_link) {
                if (strcmp(dev, mnt->um_dev) == 0)
                        break;
        }

        if (mnt == NULL && fp->f_fs != NULL) {
                free(fp->f_fs->fs_csp);
                free(fp->f_fs->fs_si);
                free(fp->f_fs);
        }

        free(fp);
        return (0);
}

/*
 * Copy a portion of a file into kernel memory.
 * Cross block boundaries when necessary.
 */
static int
ufs_read(struct open_file *f, void *start, size_t size, size_t *resid)
{
        struct file *fp = (struct file *)f->f_fsdata;
        size_t csize;
        char *buf;
        size_t buf_size;
        int rc = 0;
        char *addr = start;

        while (size != 0) {
                if (fp->f_seekp >= DIP(fp, di_size))
                        break;

                rc = buf_read_file(f, &buf, &buf_size);
                if (rc)
                        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 (rc);
}

/*
 * Write to a portion of an already allocated file.
 * Cross block boundaries when necessary. Can not
 * extend the file.
 */
static int
ufs_write(struct open_file *f, const void *start, size_t size, size_t *resid)
{
        struct file *fp = (struct file *)f->f_fsdata;
        size_t csize;
        int rc = 0;
        const char *addr = start;

        csize = size;
        while ((size != 0) && (csize != 0)) {
                if (fp->f_seekp >= DIP(fp, di_size))
                        break;

                if (csize >= 512) csize = 512; /* XXX */

                rc = buf_write_file(f, addr, &csize);
                if (rc)
                        break;

                fp->f_seekp += csize;
                addr += csize;
                size -= csize;
        }
        if (resid)
                *resid = size;
        return (rc);
}

static off_t
ufs_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 = DIP(fp, di_size) - offset;
                break;
        default:
                errno = EINVAL;
                return (-1);
        }
        return (fp->f_seekp);
}

static int
ufs_stat(struct open_file *f, struct stat *sb)
{
        struct file *fp = (struct file *)f->f_fsdata;

        /* only important stuff */
        sb->st_mode = DIP(fp, di_mode);
        sb->st_uid = DIP(fp, di_uid);
        sb->st_gid = DIP(fp, di_gid);
        sb->st_size = DIP(fp, di_size);
        sb->st_mtime = DIP(fp, di_mtime);
        /*
         * The items below are ufs specific!
         * Other fs types will need their own solution
         * if these fields are needed.
         */
        sb->st_ino = fp->f_inumber;
        /*
         * We need something to differentiate devs.
         * fs_id is unique but 64bit, we xor the two
         * halves to squeeze it into 32bits.
         */
        sb->st_dev = (dev_t)(fp->f_fs->fs_id[0] ^ fp->f_fs->fs_id[1]);

        return (0);
}

static int
ufs_readdir(struct open_file *f, struct dirent *d)
{
        struct file *fp = (struct file *)f->f_fsdata;
        struct direct *dp;
        char *buf;
        size_t buf_size;
        int error;

        /*
         * assume that a directory entry will not be split across blocks
         */

        do {
                if (fp->f_seekp >= DIP(fp, di_size))
                        return (ENOENT);
                error = buf_read_file(f, &buf, &buf_size);
                if (error)
                        return (error);
                dp = (struct direct *)buf;
                /*
                 * Check for corrupt directory entry and bail out rather
                 * than spin forever hoping that the user has other options.
                 */
                if (dp->d_reclen == 0)
                        return (0);
                fp->f_seekp += dp->d_reclen;
        } while (dp->d_ino == (ino_t)0);

        d->d_type = dp->d_type;
        strcpy(d->d_name, dp->d_name);
        return (0);
}

static int
ufs_mount(const char *dev, const char *path, void **data)
{
        char *fs;
        ufs_mnt_t *mnt;
        struct open_file *f;

        errno = 0;
        mnt = calloc(1, sizeof(*mnt));
        if (mnt == NULL)
                return (errno);
        mnt->um_fd = -1;
        mnt->um_dev = strdup(dev);
        if (mnt->um_dev == NULL)
                goto done;

        if (asprintf(&fs, "%s%s", dev, path) < 0)
                goto done;

        mnt->um_fd = open(fs, O_RDONLY);
        free(fs);
        if (mnt->um_fd == -1)
                goto done;

        /* Is it ufs file system? */
        f = fd2open_file(mnt->um_fd);
        if (strcmp(f->f_ops->fs_name, "ufs") == 0)
                STAILQ_INSERT_TAIL(&mnt_list, mnt, um_link);
        else
                errno = ENXIO;

done:
        if (errno != 0) {
                free(mnt->um_dev);
                if (mnt->um_fd >= 0)
                        close(mnt->um_fd);
                free(mnt);
        } else {
                *data = mnt;
        }

        return (errno);
}

static int
ufs_unmount(const char *dev __unused, void *data)
{
        ufs_mnt_t *mnt = data;

        STAILQ_REMOVE(&mnt_list, mnt, ufs_mnt, um_link);
        free(mnt->um_dev);
        close(mnt->um_fd);
        free(mnt);
        return (0);
}