FreeBSD/Linux Kernel Cross Reference
sys/msdosfs/msdosfs_vnops.c

     /*      $OpenBSD: msdosfs_vnops.c,v 1.139 2022/08/23 20:37:16 cheloha Exp $     */
     /*      $NetBSD: msdosfs_vnops.c,v 1.63 1997/10/17 11:24:19 ws Exp $    */
     
     /*-
      * Copyright (C) 2005 Thomas Wang.
      * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
      * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
      * All rights reserved.
      * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
     *
     * 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 TooLs GmbH.
     * 4. The name of TooLs GmbH may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
     */
    /*
     * Written by Paul Popelka (paulp@uts.amdahl.com)
     *
     * You can do anything you want with this software, just don't say you wrote
     * it, and don't remove this notice.
     *
     * This software is provided "as is".
     *
     * The author supplies this software to be publicly redistributed on the
     * understanding that the author is not responsible for the correct
     * functioning of this software in any circumstances and is not liable for
     * any damages caused by this software.
     *
     * October 1992
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/namei.h>
    #include <sys/resourcevar.h>    /* defines plimit structure in proc struct */
    #include <sys/fcntl.h>          /* define FWRITE ... */
    #include <sys/file.h>
    #include <sys/stat.h>
    #include <sys/buf.h>
    #include <sys/proc.h>
    #include <sys/mount.h>
    #include <sys/vnode.h>
    #include <sys/lock.h>
    #include <sys/signalvar.h>
    #include <sys/specdev.h> /* XXX */      /* defines v_rdev */
    #include <sys/malloc.h>
    #include <sys/pool.h>
    #include <sys/dirent.h>         /* defines dirent structure */
    #include <sys/lockf.h>
    #include <sys/unistd.h>
    
    #include <msdosfs/bpb.h>
    #include <msdosfs/direntry.h>
    #include <msdosfs/denode.h>
    #include <msdosfs/msdosfsmount.h>
    #include <msdosfs/fat.h>
    
    static uint32_t fileidhash(uint64_t);
    
    int msdosfs_bmaparray(struct vnode *, uint32_t, daddr_t *, int *);
    int msdosfs_kqfilter(void *);
    int filt_msdosfsread(struct knote *, long);
    int filt_msdosfswrite(struct knote *, long);
    int filt_msdosfsvnode(struct knote *, long);
    void filt_msdosfsdetach(struct knote *);
    
    /*
     * Some general notes:
     *
     * In the ufs filesystem the inodes, superblocks, and indirect blocks are
     * read/written using the vnode for the filesystem. Blocks that represent
     * the contents of a file are read/written using the vnode for the file
     * (including directories when they are read/written as files). This
     * presents problems for the dos filesystem because data that should be in
     * an inode (if dos had them) resides in the directory itself.  Since we
     * must update directory entries without the benefit of having the vnode
     * for the directory we must use the vnode for the filesystem.  This means
     * that when a directory is actually read/written (via read, write, or
     * readdir, or seek) we must use the vnode for the filesystem instead of
    * the vnode for the directory as would happen in ufs. This is to insure we
    * retrieve the correct block from the buffer cache since the hash value is
    * based upon the vnode address and the desired block number.
    */
   
   /*
    * Create a regular file. On entry the directory to contain the file being
    * created is locked.  We must release before we return. We must also free
    * the pathname buffer pointed at by cnp->cn_pnbuf, always on error, or
    * only if the SAVESTART bit in cn_flags is clear on success.
    */
   int
   msdosfs_create(void *v)
   {
           struct vop_create_args *ap = v;
           struct componentname *cnp = ap->a_cnp;
           struct denode ndirent;
           struct denode *dep;
           struct denode *pdep = VTODE(ap->a_dvp);
           int error;
           struct timespec ts;
   
   #ifdef MSDOSFS_DEBUG
           printf("msdosfs_create(cnp %p, vap %p\n", cnp, ap->a_vap);
   #endif
   
           /*
            * If this is the root directory and there is no space left we
            * can't do anything.  This is because the root directory can not
            * change size.
            */
           if (pdep->de_StartCluster == MSDOSFSROOT
               && pdep->de_fndoffset >= pdep->de_FileSize) {
                   error = ENOSPC;
                   goto bad;
           }
   
           /*
            * Create a directory entry for the file, then call createde() to
            * have it installed. NOTE: DOS files are always executable.  We
            * use the absence of the owner write bit to make the file
            * readonly.
            */
   #ifdef DIAGNOSTIC
           if ((cnp->cn_flags & HASBUF) == 0)
                   panic("msdosfs_create: no name");
   #endif
           bzero(&ndirent, sizeof(ndirent));
           if ((error = uniqdosname(pdep, cnp, ndirent.de_Name)) != 0)
                   goto bad;
   
           ndirent.de_Attributes = (ap->a_vap->va_mode & VWRITE) ?
                                   ATTR_ARCHIVE : ATTR_ARCHIVE | ATTR_READONLY;
           ndirent.de_StartCluster = 0;
           ndirent.de_FileSize = 0;
           ndirent.de_dev = pdep->de_dev;
           ndirent.de_devvp = pdep->de_devvp;
           ndirent.de_pmp = pdep->de_pmp;
           ndirent.de_flag = DE_ACCESS | DE_CREATE | DE_UPDATE;
           getnanotime(&ts);
           DETIMES(&ndirent, &ts, &ts, &ts);
           if ((error = createde(&ndirent, pdep, &dep, cnp)) != 0)
                   goto bad;
           if ((cnp->cn_flags & SAVESTART) == 0)
                   pool_put(&namei_pool, cnp->cn_pnbuf);
           VN_KNOTE(ap->a_dvp, NOTE_WRITE);
           *ap->a_vpp = DETOV(dep);
           return (0);
   
   bad:
           pool_put(&namei_pool, cnp->cn_pnbuf);
           return (error);
   }
   
   int
   msdosfs_mknod(void *v)
   {
           struct vop_mknod_args *ap = v;
   
           pool_put(&namei_pool, ap->a_cnp->cn_pnbuf);
           VN_KNOTE(ap->a_dvp, NOTE_WRITE);
           return (EINVAL);
   }
   
   int
   msdosfs_open(void *v)
   {
           return (0);
   }
   
   int
   msdosfs_close(void *v)
   {
           struct vop_close_args *ap = v;
           struct vnode *vp = ap->a_vp;
           struct denode *dep = VTODE(vp);
           struct timespec ts;
   
           if (vp->v_usecount > 1 && !VOP_ISLOCKED(vp)) {
                   getnanotime(&ts);
                   DETIMES(dep, &ts, &ts, &ts);
           }
           return (0);
   }
   
   int
   msdosfs_access(void *v)
   {
           struct vop_access_args *ap = v;
           struct denode *dep = VTODE(ap->a_vp);
           struct msdosfsmount *pmp = dep->de_pmp;
           mode_t dosmode;
   
           dosmode = (S_IRUSR | S_IRGRP | S_IROTH);
           if ((dep->de_Attributes & ATTR_READONLY) == 0)
                   dosmode |= (S_IWUSR | S_IWGRP | S_IWOTH);
           if (dep->de_Attributes & ATTR_DIRECTORY)
                   dosmode |= (S_IXUSR | S_IXGRP | S_IXOTH);
           dosmode &= pmp->pm_mask;
   
           return (vaccess(ap->a_vp->v_type, dosmode, pmp->pm_uid, pmp->pm_gid,
               ap->a_mode, ap->a_cred));
   }
   
   int
   msdosfs_getattr(void *v)
   {
           struct vop_getattr_args *ap = v;
           struct denode *dep = VTODE(ap->a_vp);
           struct msdosfsmount *pmp = dep->de_pmp;
           struct vattr *vap = ap->a_vap;
           struct timespec ts;
           uint32_t fileid;
   
           getnanotime(&ts);
           DETIMES(dep, &ts, &ts, &ts);
           vap->va_fsid = dep->de_dev;
   
           /*
            * The following computation of the fileid must be the same as
            * that used in msdosfs_readdir() to compute d_fileno. If not,
            * pwd doesn't work.
            *
            * We now use the starting cluster number as the fileid/fileno.
            * This works for both files and directories (including the root
            * directory, on FAT32).  Even on FAT32, this will at most be a
            * 28-bit number, as the high 4 bits of FAT32 cluster numbers
            * are reserved.
            *
            * However, we do need to do something for 0-length files, which
            * will not have a starting cluster number.
            *
            * These files cannot be directories, since (except for /, which
            * is special-cased anyway) directories contain entries for . and
            * .., so must have non-zero length.
            *
            * In this case, we just create a non-cryptographic hash of the
            * original fileid calculation, and set the top bit.
            *
            * This algorithm has the benefit that all directories, and all
            * non-zero-length files, will have fileids that are persistent
            * across mounts and reboots, and that cannot collide (as long
            * as the filesystem is not corrupt).  Zero-length files will
            * have fileids that are persistent, but that may collide.  We
            * will just have to live with that.
            */
           fileid = dep->de_StartCluster;
   
           if (dep->de_Attributes & ATTR_DIRECTORY) {
                   /* Special-case root */
                   if (dep->de_StartCluster == MSDOSFSROOT)
                           fileid = FAT32(pmp) ? pmp->pm_rootdirblk : 1;
           } else {
                   if (dep->de_FileSize == 0) {
                           uint32_t dirsperblk;
                           uint64_t fileid64;
   
                           dirsperblk = pmp->pm_BytesPerSec /
                               sizeof(struct direntry);
   
                           fileid64 = (dep->de_dirclust == MSDOSFSROOT) ?
                               roottobn(pmp, 0) : cntobn(pmp, dep->de_dirclust);
                           fileid64 *= dirsperblk;
                           fileid64 += dep->de_diroffset / sizeof(struct direntry);
   
                           fileid = fileidhash(fileid64);
                   }
           }
   
           vap->va_fileid = fileid;
           vap->va_mode = (S_IRUSR|S_IRGRP|S_IROTH);
           if ((dep->de_Attributes & ATTR_READONLY) == 0)
                   vap->va_mode |= (S_IWUSR|S_IWGRP|S_IWOTH);
           if (dep->de_Attributes & ATTR_DIRECTORY) {
                   vap->va_mode |= S_IFDIR;
                   vap->va_mode |= (vap->va_mode & S_IRUSR) ? S_IXUSR : 0;
                   vap->va_mode |= (vap->va_mode & S_IRGRP) ? S_IXGRP : 0;
                   vap->va_mode |= (vap->va_mode & S_IROTH) ? S_IXOTH : 0;
           }
           vap->va_mode &= dep->de_pmp->pm_mask;
           vap->va_nlink = 1;
           vap->va_gid = dep->de_pmp->pm_gid;
           vap->va_uid = dep->de_pmp->pm_uid;
           vap->va_rdev = 0;
           vap->va_size = dep->de_FileSize;
           dos2unixtime(dep->de_MDate, dep->de_MTime, 0, &vap->va_mtime);
           if (dep->de_pmp->pm_flags & MSDOSFSMNT_LONGNAME) {
                   dos2unixtime(dep->de_ADate, 0, 0, &vap->va_atime);
                   dos2unixtime(dep->de_CDate, dep->de_CTime, dep->de_CTimeHundredth, &vap->va_ctime);
           } else {
                   vap->va_atime = vap->va_mtime;
                   vap->va_ctime = vap->va_mtime;
           }
           vap->va_flags = 0;
           if ((dep->de_Attributes & ATTR_ARCHIVE) == 0)
                   vap->va_flags |= SF_ARCHIVED;
           vap->va_gen = 0;
           vap->va_blocksize = dep->de_pmp->pm_bpcluster;
           vap->va_bytes = (dep->de_FileSize + dep->de_pmp->pm_crbomask) &
                                   ~(dep->de_pmp->pm_crbomask);
           vap->va_type = ap->a_vp->v_type;
           return (0);
   }
   
   int
   msdosfs_setattr(void *v)
   {
           struct vop_setattr_args *ap = v;
           struct vnode *vp = ap->a_vp;
           struct denode *dep = VTODE(ap->a_vp);
           struct msdosfsmount *pmp = dep->de_pmp;
           struct vattr *vap = ap->a_vap;
           struct ucred *cred = ap->a_cred;
           int error = 0;
   
   #ifdef MSDOSFS_DEBUG
           printf("msdosfs_setattr(): vp %p, vap %p, cred %p, p %p\n",
               ap->a_vp, vap, cred, ap->a_p);
   #endif
           if ((vap->va_type != VNON) || (vap->va_nlink != VNOVAL) ||
               (vap->va_fsid != VNOVAL) || (vap->va_fileid != VNOVAL) ||
               (vap->va_blocksize != VNOVAL) || (vap->va_rdev != VNOVAL) ||
               (vap->va_bytes != VNOVAL) || (vap->va_gen != VNOVAL)) {
   #ifdef MSDOSFS_DEBUG
                   printf("msdosfs_setattr(): returning EINVAL\n");
                   printf("    va_type %d, va_nlink %x, va_fsid %ld, "
                       "va_fileid %llx\n", vap->va_type, vap->va_nlink,
                       vap->va_fsid, (unsigned long long)vap->va_fileid);
                   printf("    va_blocksize %lx, va_rdev %x, va_bytes %llx, "
                       "va_gen %lx\n", vap->va_blocksize,
                       (unsigned int)vap->va_rdev,
                       (unsigned long long)vap->va_bytes, vap->va_gen);
   #endif
                   return (EINVAL);
           }
           if (vap->va_flags != VNOVAL) {
                   if (vp->v_mount->mnt_flag & MNT_RDONLY)
                           return (EINVAL);
                   if (cred->cr_uid != pmp->pm_uid) {
                           error = suser_ucred(cred);
                           if (error)
                                   return (error);
                   }
                   /*
                    * We are very inconsistent about handling unsupported
                    * attributes.  We ignored the access time and the
                    * read and execute bits.  We were strict for the other
                    * attributes.
                    *
                    * Here we are strict, stricter than ufs in not allowing
                    * users to attempt to set SF_SETTABLE bits or anyone to
                    * set unsupported bits.  However, we ignore attempts to
                    * set ATTR_ARCHIVE for directories `cp -pr' from a more
                    * sensible filesystem attempts it a lot.
                    */
                   if (vap->va_flags & SF_SETTABLE) {
                           error = suser_ucred(cred);
                           if (error)
                                   return (error);
                   }
                   if (vap->va_flags & ~SF_ARCHIVED)
                           return EOPNOTSUPP;
                   if (vap->va_flags & SF_ARCHIVED)
                           dep->de_Attributes &= ~ATTR_ARCHIVE;
                   else if (!(dep->de_Attributes & ATTR_DIRECTORY))
                           dep->de_Attributes |= ATTR_ARCHIVE;
                   dep->de_flag |= DE_MODIFIED;
           }
   
           if (vap->va_uid != (uid_t)VNOVAL || vap->va_gid != (gid_t)VNOVAL) {
                   uid_t uid;
                   gid_t gid;
   
                   if (vp->v_mount->mnt_flag & MNT_RDONLY)
                           return (EINVAL);
                   uid = vap->va_uid;
                   if (uid == (uid_t)VNOVAL)
                           uid = pmp->pm_uid;
                   gid = vap->va_gid;
                   if (gid == (gid_t)VNOVAL)
                           gid = pmp->pm_gid;
                   if (cred->cr_uid != pmp->pm_uid || uid != pmp->pm_uid ||
                       (gid != pmp->pm_gid && !groupmember(gid, cred))) {
                           error = suser_ucred(cred);
                           if (error)
                                   return (error);
                   }
                   if (uid != pmp->pm_uid || gid != pmp->pm_gid)
                           return EINVAL;
           }
   
           if (vap->va_size != VNOVAL) {
                   switch (vp->v_type) {
                   case VDIR:
                           return (EISDIR);
                   case VREG:
                           /*
                            * Truncation is only supported for regular files,
                            * Disallow it if the filesystem is read-only.
                            */
                           if (vp->v_mount->mnt_flag & MNT_RDONLY)
                                   return (EINVAL);
                           break;
                   default:
                           /*
                            * According to POSIX, the result is unspecified
                            * for file types other than regular files,
                            * directories and shared memory objects.  We
                            * don't support any file types except regular
                            * files and directories in this file system, so
                            * this (default) case is unreachable and can do
                            * anything.  Keep falling through to detrunc()
                            * for now.
                            */
                           break;
                   }
                   error = detrunc(dep, vap->va_size, 0, cred, ap->a_p);
                   if (error)
                           return error;
           }
           if ((vap->va_vaflags & VA_UTIMES_CHANGE) ||
               vap->va_atime.tv_nsec != VNOVAL ||
               vap->va_mtime.tv_nsec != VNOVAL) {
                   if (vp->v_mount->mnt_flag & MNT_RDONLY)
                           return (EINVAL);
                   if (cred->cr_uid != pmp->pm_uid &&
                       (error = suser_ucred(cred)) &&
                       ((vap->va_vaflags & VA_UTIMES_NULL) == 0 ||
                       (error = VOP_ACCESS(ap->a_vp, VWRITE, cred, ap->a_p))))
                           return (error);
                   if (vp->v_type != VDIR) {
                           if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95) == 0 &&
                               vap->va_atime.tv_nsec != VNOVAL) {
                                   dep->de_flag &= ~DE_ACCESS;
                                   unix2dostime(&vap->va_atime, &dep->de_ADate,
                                       NULL, NULL);
                           }
                           if (vap->va_mtime.tv_nsec != VNOVAL) {
                                   dep->de_flag &= ~DE_UPDATE;
                                   unix2dostime(&vap->va_mtime, &dep->de_MDate,
                                       &dep->de_MTime, NULL);
                           }
                           dep->de_Attributes |= ATTR_ARCHIVE;
                           dep->de_flag |= DE_MODIFIED;
                   }
           }
           /*
            * DOS files only have the ability to have their writability
            * attribute set, so we use the owner write bit to set the readonly
            * attribute.
            */
           if (vap->va_mode != (mode_t)VNOVAL) {
                   if (vp->v_mount->mnt_flag & MNT_RDONLY)
                           return (EINVAL);
                   if (cred->cr_uid != pmp->pm_uid) {
                           error = suser_ucred(cred);
                           if (error)
                                   return (error);
                   }
                   if (vp->v_type != VDIR) {
                           /* We ignore the read and execute bits. */
                           if (vap->va_mode & VWRITE)
                                   dep->de_Attributes &= ~ATTR_READONLY;
                           else
                                   dep->de_Attributes |= ATTR_READONLY;
                           dep->de_Attributes |= ATTR_ARCHIVE;
                           dep->de_flag |= DE_MODIFIED;
                   }
           }
           VN_KNOTE(ap->a_vp, NOTE_ATTRIB);
           return (deupdat(dep, 1));
   }
   
   int
   msdosfs_read(void *v)
   {
           struct vop_read_args *ap = v;
           struct vnode *vp = ap->a_vp;
           struct denode *dep = VTODE(vp);
           struct msdosfsmount *pmp = dep->de_pmp;
           struct uio *uio = ap->a_uio;
           int isadir, error = 0;
           uint32_t n, diff, size, on;
           struct buf *bp;
           uint32_t cn;
           daddr_t bn;
   
           /*
            * If they didn't ask for any data, then we are done.
            */
           if (uio->uio_resid == 0)
                   return (0);
           if (uio->uio_offset < 0)
                   return (EINVAL);
   
           isadir = dep->de_Attributes & ATTR_DIRECTORY;
           do {
                   if (uio->uio_offset >= dep->de_FileSize)
                           return (0);
   
                   cn = de_cluster(pmp, uio->uio_offset);
                   size = pmp->pm_bpcluster;
                   on = uio->uio_offset & pmp->pm_crbomask;
                   n = ulmin(pmp->pm_bpcluster - on, uio->uio_resid);
   
                   /*
                    * de_FileSize is uint32_t, and we know that uio_offset <
                    * de_FileSize, so uio->uio_offset < 2^32.  Therefore
                    * the cast to uint32_t on the next line is safe.
                    */
                   diff = dep->de_FileSize - (uint32_t)uio->uio_offset;
                   if (diff < n)
                           n = diff;
   
                   /*
                    * If we are operating on a directory file then be sure to
                    * do i/o with the vnode for the filesystem instead of the
                    * vnode for the directory.
                    */
                   if (isadir) {
                           /* convert cluster # to block # */
                           error = pcbmap(dep, cn, &bn, 0, &size);
                           if (error)
                                   return (error);
                           error = bread(pmp->pm_devvp, bn, size, &bp);
                   } else {
                           if (de_cn2off(pmp, cn + 1) >= dep->de_FileSize)
                                   error = bread(vp, cn, size, &bp);
                           else
                                   error = bread_cluster(vp, cn, size, &bp);
                   }
                   n = min(n, pmp->pm_bpcluster - bp->b_resid);
                   if (error) {
                           brelse(bp);
                           return (error);
                   }
                   error = uiomove(bp->b_data + on, n, uio);
                   brelse(bp);
           } while (error == 0 && uio->uio_resid > 0 && n != 0);
           if (!isadir && !(vp->v_mount->mnt_flag & MNT_NOATIME))
                   dep->de_flag |= DE_ACCESS;
           return (error);
   }
   
   /*
    * Write data to a file or directory.
    */
   int
   msdosfs_write(void *v)
   {
           struct vop_write_args *ap = v;
           uint32_t n, croffset;
           size_t resid;
           ssize_t overrun;
           int extended = 0;
           uint32_t osize;
           int error = 0;
           uint32_t count, lastcn, cn;
           struct buf *bp;
           int ioflag = ap->a_ioflag;
           struct uio *uio = ap->a_uio;
           struct vnode *vp = ap->a_vp;
           struct vnode *thisvp;
           struct denode *dep = VTODE(vp);
           struct msdosfsmount *pmp = dep->de_pmp;
           struct ucred *cred = ap->a_cred;
   
   #ifdef MSDOSFS_DEBUG
           printf("msdosfs_write(vp %p, uio %p, ioflag %08x, cred %p\n",
               vp, uio, ioflag, cred);
           printf("msdosfs_write(): diroff %d, dirclust %d, startcluster %d\n",
               dep->de_diroffset, dep->de_dirclust, dep->de_StartCluster);
   #endif
   
           switch (vp->v_type) {
           case VREG:
                   if (ioflag & IO_APPEND)
                           uio->uio_offset = dep->de_FileSize;
                   thisvp = vp;
                   break;
           case VDIR:
                   return EISDIR;
           default:
                   panic("msdosfs_write(): bad file type");
           }
   
           if (uio->uio_offset < 0)
                   return (EINVAL);
   
           if (uio->uio_resid == 0)
                   return (0);
   
           /* Don't bother to try to write files larger than the f/s limit */
           if (uio->uio_offset > MSDOSFS_FILESIZE_MAX ||
               uio->uio_resid > (MSDOSFS_FILESIZE_MAX - uio->uio_offset))
                   return (EFBIG);
   
           /* do the filesize rlimit check */
           if ((error = vn_fsizechk(vp, uio, ioflag, &overrun)))
                   return (error);
   
           /*
            * If the offset we are starting the write at is beyond the end of
            * the file, then they've done a seek.  Unix filesystems allow
            * files with holes in them, DOS doesn't so we must fill the hole
            * with zeroed blocks.
            */
           if (uio->uio_offset > dep->de_FileSize) {
                   if ((error = deextend(dep, uio->uio_offset, cred)) != 0)
                           goto out;
           }
   
           /*
            * Remember some values in case the write fails.
            */
           resid = uio->uio_resid;
           osize = dep->de_FileSize;
   
           /*
            * If we write beyond the end of the file, extend it to its ultimate
            * size ahead of the time to hopefully get a contiguous area.
            */
           if (uio->uio_offset + resid > osize) {
                   extended = 1;
                   count = de_clcount(pmp, uio->uio_offset + resid) -
                           de_clcount(pmp, osize);
                   if ((error = extendfile(dep, count, NULL, NULL, 0)) &&
                       (error != ENOSPC || (ioflag & IO_UNIT)))
                           goto errexit;
                   lastcn = dep->de_fc[FC_LASTFC].fc_frcn;
           } else
                   lastcn = de_clcount(pmp, osize) - 1;
   
           do {
                   croffset = uio->uio_offset & pmp->pm_crbomask;
                   cn = de_cluster(pmp, uio->uio_offset);
   
                   if (cn > lastcn) {
                           error = ENOSPC;
                           break;
                   }
   
                   if (croffset == 0 &&
                       (de_cluster(pmp, uio->uio_offset + uio->uio_resid) > cn ||
                        (uio->uio_offset + uio->uio_resid) >= dep->de_FileSize)) {
                           /*
                            * If either the whole cluster gets written,
                            * or we write the cluster from its start beyond EOF,
                            * then no need to read data from disk.
                            */
                           bp = getblk(thisvp, cn, pmp->pm_bpcluster, 0, INFSLP);
                           clrbuf(bp);
                           /*
                            * Do the bmap now, since pcbmap needs buffers
                            * for the fat table. (see msdosfs_strategy)
                            */
                           if (bp->b_blkno == bp->b_lblkno) {
                                   error = pcbmap(dep, bp->b_lblkno, &bp->b_blkno, 0, 0);
                                   if (error)
                                           bp->b_blkno = -1;
                           }
                           if (bp->b_blkno == -1) {
                                   brelse(bp);
                                   if (!error)
                                           error = EIO;            /* XXX */
                                   break;
                           }
                   } else {
                           /*
                            * The block we need to write into exists, so
                            * read it in.
                            */
                           error = bread(thisvp, cn, pmp->pm_bpcluster, &bp);
                           if (error) {
                                   brelse(bp);
                                   break;
                           }
                   }
   
                   n = ulmin(uio->uio_resid, pmp->pm_bpcluster - croffset);
                   if (uio->uio_offset + n > dep->de_FileSize) {
                           dep->de_FileSize = uio->uio_offset + n;
                           uvm_vnp_setsize(vp, dep->de_FileSize);
                   }
                   uvm_vnp_uncache(vp);
                   /*
                    * Should these vnode_pager_* functions be done on dir
                    * files?
                    */
   
                   /*
                    * Copy the data from user space into the buf header.
                    */
                   error = uiomove(bp->b_data + croffset, n, uio);
   
                   /*
                    * If they want this synchronous then write it and wait for
                    * it.  Otherwise, if on a cluster boundary write it
                    * asynchronously so we can move on to the next block
                    * without delay.  Otherwise do a delayed write because we
                    * may want to write somemore into the block later.
                    */
   #if 0
                   if (ioflag & IO_NOCACHE)
                           bp->b_flags |= B_NOCACHE;
   #endif
                   if (ioflag & IO_SYNC)
                           (void) bwrite(bp);
                   else if (n + croffset == pmp->pm_bpcluster)
                           bawrite(bp);
                   else
                           bdwrite(bp);
                   dep->de_flag |= DE_UPDATE;
           } while (error == 0 && uio->uio_resid > 0);
   
           if (resid > uio->uio_resid)
                    VN_KNOTE(ap->a_vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0));
   
           if (dep->de_FileSize < osize)
                   VN_KNOTE(ap->a_vp, NOTE_TRUNCATE);
   
           /*
            * If the write failed and they want us to, truncate the file back
            * to the size it was before the write was attempted.
            */
   errexit:
           if (error) {
                   if (ioflag & IO_UNIT) {
                           detrunc(dep, osize, ioflag & IO_SYNC, NOCRED, curproc);
                           uio->uio_offset -= resid - uio->uio_resid;
                           uio->uio_resid = resid;
                   } else {
                           detrunc(dep, dep->de_FileSize, ioflag & IO_SYNC, NOCRED, curproc);
                           if (uio->uio_resid != resid)
                                   error = 0;
                   }
           } else if (ioflag & IO_SYNC)
                   error = deupdat(dep, 1);
   
   out:
           /* correct the result for writes clamped by vn_fsizechk() */
           uio->uio_resid += overrun;
           return (error);
   }
   
   int
   msdosfs_ioctl(void *v)
   {
           return (ENOTTY);
   }
   
   /*
    * Flush the blocks of a file to disk.
    *
    * This function is worthless for vnodes that represent directories. Maybe we
    * could just do a sync if they try an fsync on a directory file.
    */
   int
   msdosfs_fsync(void *v)
   {
           struct vop_fsync_args *ap = v;
           struct vnode *vp = ap->a_vp;
   
           vflushbuf(vp, ap->a_waitfor == MNT_WAIT);
           return (deupdat(VTODE(vp), ap->a_waitfor == MNT_WAIT));
   }
   
   /*
    * Flush the blocks of a file to disk.
    *
    * This function is worthless for vnodes that represent directories. Maybe we
    * could just do a sync if they try an fsync on a directory file.
    */
   int
   msdosfs_remove(void *v)
   {
           struct vop_remove_args *ap = v;
           struct denode *dep = VTODE(ap->a_vp);
           struct denode *ddep = VTODE(ap->a_dvp);
           int error;
   
           if (ap->a_vp->v_type == VDIR)
                   error = EPERM;
           else
                   error = removede(ddep, dep);
   
           VN_KNOTE(ap->a_vp, NOTE_DELETE);
           VN_KNOTE(ap->a_dvp, NOTE_WRITE);
   
   #ifdef MSDOSFS_DEBUG
           printf("msdosfs_remove(), dep %p, v_usecount %d\n", dep,
               ap->a_vp->v_usecount);
   #endif
           if (ddep == dep)
                   vrele(ap->a_vp);
           else
                   vput(ap->a_vp); /* causes msdosfs_inactive() to be called
                                    * via vrele() */
           vput(ap->a_dvp);
           return (error);
   }
   
   /*
    * DOS filesystems don't know what links are. But since we already called
    * msdosfs_lookup() with create and lockparent, the parent is locked so we
    * have to free it before we return the error.
    */
   int
   msdosfs_link(void *v)
   {
           struct vop_link_args *ap = v;
   
           VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
           vput(ap->a_dvp);
           return (EOPNOTSUPP);
   }
   
   /*
    * Renames on files require moving the denode to a new hash queue since the
    * denode's location is used to compute which hash queue to put the file
    * in. Unless it is a rename in place.  For example "mv a b".
    *
    * What follows is the basic algorithm:
    *
    * if (file move) {
    *      if (dest file exists) {
    *              remove dest file
    *      }
    *      if (dest and src in same directory) {
    *              rewrite name in existing directory slot
    *      } else {
    *              write new entry in dest directory
    *              update offset and dirclust in denode
    *              move denode to new hash chain
    *              clear old directory entry
    *      }
    * } else {
    *      directory move
    *      if (dest directory exists) {
    *              if (dest is not empty) {
    *                      return ENOTEMPTY
    *              }
    *              remove dest directory
    *      }
    *      if (dest and src in same directory) {
    *              rewrite name in existing entry
    *      } else {
    *              be sure dest is not a child of src directory
    *              write entry in dest directory
    *              update "." and ".." in moved directory
    *              update offset and dirclust in denode
    *              move denode to new hash chain
    *              clear old directory entry for moved directory
    *      }
    * }
    *
    * On entry:
    *      source's parent directory is unlocked
    *      source file or directory is unlocked
    *      destination's parent directory is locked
    *      destination file or directory is locked if it exists
    *
    * On exit:
    *      all denodes should be released
    *
    * Notes:
    * I'm not sure how the memory containing the pathnames pointed at by the
    * componentname structures is freed, there may be some memory bleeding
    * for each rename done.
    */
   int
   msdosfs_rename(void *v)
   {
           struct vop_rename_args *ap = v;
           struct vnode *tvp = ap->a_tvp;
           struct vnode *tdvp = ap->a_tdvp;
           struct vnode *fvp = ap->a_fvp;
           struct vnode *fdvp = ap->a_fdvp;
           struct componentname *tcnp = ap->a_tcnp;
           struct componentname *fcnp = ap->a_fcnp;
           struct denode *ip, *xp, *dp, *zp;
           u_char toname[11], oldname[11];
           uint32_t from_diroffset, to_diroffset;
           u_char to_count;
           int doingdirectory = 0, newparent = 0;
           int error;
           uint32_t cn, pcl;
           daddr_t bn;
           struct msdosfsmount *pmp;
           struct direntry *dotdotp;
           struct buf *bp;
   
           pmp = VFSTOMSDOSFS(fdvp->v_mount);
   
   #ifdef DIAGNOSTIC
           if ((tcnp->cn_flags & HASBUF) == 0 ||
               (fcnp->cn_flags & HASBUF) == 0)
                   panic("msdosfs_rename: no name");
   #endif
           /*
            * Check for cross-device rename.
            */
           if ((fvp->v_mount != tdvp->v_mount) ||
               (tvp && (fvp->v_mount != tvp->v_mount))) {
                   error = EXDEV;
   abortit:
                   VOP_ABORTOP(tdvp, tcnp);
                   if (tdvp == tvp)
                           vrele(tdvp);
                   else
                           vput(tdvp);
                   if (tvp)
                           vput(tvp);
                   VOP_ABORTOP(fdvp, fcnp);
                   vrele(fdvp);
                   vrele(fvp);
                   return (error);
           }
   
           /*
            * If source and dest are the same, do nothing.
            */
           if (tvp == fvp) {
                   error = 0;
                   goto abortit;
           }
   
           /* */
           if ((error = vn_lock(fvp, LK_EXCLUSIVE | LK_RETRY)) != 0)
                   goto abortit;
           dp = VTODE(fdvp);
           ip = VTODE(fvp);
   
           /*
            * Be sure we are not renaming ".", "..", or an alias of ".". This
            * leads to a crippled directory tree.  It's pretty tough to do a
            * "ls" or "pwd" with the "." directory entry missing, and "cd .."
            * doesn't work if the ".." entry is missing.
            */
           if (ip->de_Attributes & ATTR_DIRECTORY) {
                   /*
                    * Avoid ".", "..", and aliases of "." for obvious reasons.
                    */
                   if ((fcnp->cn_namelen == 1 && fcnp->cn_nameptr[0] == '.') ||
                       dp == ip ||
                       (fcnp->cn_flags & ISDOTDOT) ||
                       (tcnp->cn_flags & ISDOTDOT) ||
                       (ip->de_flag & DE_RENAME)) {
                           VOP_UNLOCK(fvp);
                           error = EINVAL;
                           goto abortit;
                   }
                   ip->de_flag |= DE_RENAME;
                   doingdirectory++;
           }
           VN_KNOTE(fdvp, NOTE_WRITE);     /* XXX right place? */
   
           /*
            * When the target exists, both the directory
            * and target vnodes are returned locked.
            */
           dp = VTODE(tdvp);
           xp = tvp ? VTODE(tvp) : NULL;
           /*
            * Remember direntry place to use for destination
            */
           to_diroffset = dp->de_fndoffset;
           to_count = dp->de_fndcnt;
   
           /*
            * If ".." must be changed (ie the directory gets a new
            * parent) then the source directory must not be in the
            * directory hierarchy above the target, as this would
            * orphan everything below the source directory. Also
            * the user must have write permission in the source so
            * as to be able to change "..". We must repeat the call
            * to namei, as the parent directory is unlocked by the
            * call to doscheckpath().
            */
           error = VOP_ACCESS(fvp, VWRITE, tcnp->cn_cred, tcnp->cn_proc);
          VOP_UNLOCK(fvp);
          if (VTODE(fdvp)->de_StartCluster != VTODE(tdvp)->de_StartCluster)
                  newparent = 1;
          vrele(fdvp);
          if (doingdirectory && newparent) {
                  if (error)      /* write access check above */
                          goto bad1;
                  if (xp != NULL)
                          vput(tvp);
                  /*
                   * doscheckpath() vput()'s dp,
                   * so we have to do a relookup afterwards
                   */
                  if ((error = doscheckpath(ip, dp)) != 0)
                          goto out;
                  if ((tcnp->cn_flags & SAVESTART) == 0)
                          panic("msdosfs_rename: lost to startdir");
                  if ((error = vfs_relookup(tdvp, &tvp, tcnp)) != 0)
                          goto out;
                  dp = VTODE(tdvp);
                  xp = tvp ? VTODE(tvp) : NULL;
          }
  
          VN_KNOTE(tdvp, NOTE_WRITE);
  
          if (xp != NULL) {
                  /*
                   * Target must be empty if a directory and have no links
                   * to it. Also, ensure source and target are compatible
                   * (both directories, or both not directories).
                   */
                  if (xp->de_Attributes & ATTR_DIRECTORY) {
                          if (!dosdirempty(xp)) {
                                  error = ENOTEMPTY;
                                  goto bad1;
                          }
                          if (!doingdirectory) {
                                  error = ENOTDIR;
                                  goto bad1;
                          }
                          cache_purge(tdvp);
                  } else if (doingdirectory) {
                          error = EISDIR;
                          goto bad1;
                  }
                  if ((error = removede(dp, xp)) != 0)
                          goto bad1;
                  VN_KNOTE(tvp, NOTE_DELETE);
                  vput(tvp);
                  xp = NULL;
          }
  
          /*
           * Convert the filename in tcnp into a dos filename. We copy this
           * into the denode and directory entry for the destination
           * file/directory.
           */
          if ((error = uniqdosname(VTODE(tdvp), tcnp, toname)) != 0)
                  goto bad1;
  
          /*
           * Since from wasn't locked at various places above,
           * have to do a relookup here.
           */
          fcnp->cn_flags &= ~MODMASK;
          fcnp->cn_flags |= LOCKPARENT | LOCKLEAF;
          if ((fcnp->cn_flags & SAVESTART) == 0)
                  panic("msdosfs_rename: lost from startdir");
          if (!newparent)
                  VOP_UNLOCK(tdvp);
          (void) vfs_relookup(fdvp, &fvp, fcnp);
          if (fvp == NULL) {
                  /*
                   * From name has disappeared.
                   */
                  if (doingdirectory)
                          panic("rename: lost dir entry");
                  vrele(ap->a_fvp);
                  if (newparent)
                          VOP_UNLOCK(tdvp);
                  vrele(tdvp);
                  return 0;
          }
          xp = VTODE(fvp);
          zp = VTODE(fdvp);
          from_diroffset = zp->de_fndoffset;
  
          /*
           * Ensure that the directory entry still exists and has not
           * changed till now. If the source is a file the entry may
           * have been unlinked or renamed. In either case there is
           * no further work to be done. If the source is a directory
           * then it cannot have been rmdir'ed or renamed; this is
           * prohibited by the DE_RENAME flag.
           */
          if (xp != ip) {
                  if (doingdirectory)
                          panic("rename: lost dir entry");
                  vrele(ap->a_fvp);
                  if (newparent)
                          VOP_UNLOCK(fdvp);
                  xp = NULL;
          } else {
                  vrele(fvp);
                  xp = NULL;
  
                  /*
                   * First write a new entry in the destination
                   * directory and mark the entry in the source directory
                   * as deleted.  Then move the denode to the correct hash
                   * chain for its new location in the filesystem.  And, if
                   * we moved a directory, then update its .. entry to point
                   * to the new parent directory.
                   */
                  bcopy(ip->de_Name, oldname, 11);
                  bcopy(toname, ip->de_Name, 11); /* update denode */
                  dp->de_fndoffset = to_diroffset;
                  dp->de_fndcnt = to_count;
                  error = createde(ip, dp, NULL, tcnp);
                  if (error) {
                          bcopy(oldname, ip->de_Name, 11);
                          if (newparent)
                                  VOP_UNLOCK(fdvp);
                          goto bad;
                  }
                  ip->de_refcnt++;
                  zp->de_fndoffset = from_diroffset;
                  if ((error = removede(zp, ip)) != 0) {
                          /* XXX should really panic here, fs is corrupt */
                          if (newparent)
                                  VOP_UNLOCK(fdvp);
                          goto bad;
                  }
  
                  cache_purge(fvp);
  
                  if (!doingdirectory) {
                          error = pcbmap(dp, de_cluster(pmp, to_diroffset), 0,
                                         &ip->de_dirclust, 0);
                          if (error) {
                                  /* XXX should really panic here, fs is corrupt */
                                  if (newparent)
                                          VOP_UNLOCK(fdvp);
                                  goto bad;
                          }
                          ip->de_diroffset = to_diroffset;
                          if (ip->de_dirclust != MSDOSFSROOT)
                                  ip->de_diroffset &= pmp->pm_crbomask;
                  }
                  reinsert(ip);
                  if (newparent)
                          VOP_UNLOCK(fdvp);
          }
  
          /*
           * If we moved a directory to a new parent directory, then we must
           * fixup the ".." entry in the moved directory.
           */
          if (doingdirectory && newparent) {
                  cn = ip->de_StartCluster;
                  if (cn == MSDOSFSROOT) {
                          /* this should never happen */
                          panic("msdosfs_rename: updating .. in root directory?");
                  } else
                          bn = cntobn(pmp, cn);
                  error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, &bp);
                  if (error) {
                          /* XXX should really panic here, fs is corrupt */
                          brelse(bp);
                          goto bad;
                  }
                  dotdotp = (struct direntry *)bp->b_data;
                  putushort(dotdotp[0].deStartCluster, cn);
                  pcl = dp->de_StartCluster;
                  if (FAT32(pmp) && pcl == pmp->pm_rootdirblk)
                          pcl = 0;
                  putushort(dotdotp[1].deStartCluster, pcl);
                  if (FAT32(pmp)) {
                          putushort(dotdotp[0].deHighClust, cn >> 16);
                          putushort(dotdotp[1].deHighClust, pcl >> 16);
                  }
                  if ((error = bwrite(bp)) != 0) {
                          /* XXX should really panic here, fs is corrupt */
                          goto bad;
                  }
          }
  
          VN_KNOTE(fvp, NOTE_RENAME);
  
  bad:
          VOP_UNLOCK(fvp);
          vrele(fdvp);
  bad1:
          if (xp)
                  vput(tvp);
          vput(tdvp);
  out:
          ip->de_flag &= ~DE_RENAME;
          vrele(fvp);
          return (error);
  
  }
  
  struct {
          struct direntry dot;
          struct direntry dotdot;
  } dosdirtemplate = {
          {       ".       ", "   ",                      /* the . entry */
                  ATTR_DIRECTORY,                         /* file attribute */
                  CASE_LOWER_BASE | CASE_LOWER_EXT,       /* lower case */
                  0,                                      /* create time 100ths */
                  { 0, 0 }, { 0, 0 },                     /* create time & date */
                  { 0, 0 },                               /* access date */
                  { 0, 0 },                               /* high bits of start cluster */
                  { 210, 4 }, { 210, 4 },                 /* modify time & date */
                  { 0, 0 },                               /* startcluster */
                  { 0, 0, 0, 0 }                          /* filesize */
          },
          {       "..      ", "   ",                      /* the .. entry */
                  ATTR_DIRECTORY,                         /* file attribute */
                  CASE_LOWER_BASE | CASE_LOWER_EXT,       /* lower case */
                  0,                                      /* create time 100ths */
                  { 0, 0 }, { 0, 0 },                     /* create time & date */
                  { 0, 0 },                               /* access date */
                  { 0, 0 },                               /* high bits of start cluster */
                  { 210, 4 }, { 210, 4 },                 /* modify time & date */
                  { 0, 0 },                               /* startcluster */
                  { 0, 0, 0, 0 }                          /* filesize */
          }
  };
  
  int
  msdosfs_mkdir(void *v)
  {
          struct vop_mkdir_args *ap = v;
          struct componentname *cnp = ap->a_cnp;
          struct denode ndirent;
          struct denode *dep;
          struct denode *pdep = VTODE(ap->a_dvp);
          int error;
          daddr_t bn;
          uint32_t newcluster, pcl;
          struct direntry *denp;
          struct msdosfsmount *pmp = pdep->de_pmp;
          struct buf *bp;
          struct timespec ts;
  
          /*
           * If this is the root directory and there is no space left we
           * can't do anything.  This is because the root directory can not
           * change size.
           */
          if (pdep->de_StartCluster == MSDOSFSROOT
              && pdep->de_fndoffset >= pdep->de_FileSize) {
                  error = ENOSPC;
                  goto bad2;
          }
  
          /*
           * Allocate a cluster to hold the about to be created directory.
           */
          error = clusteralloc(pmp, 0, 1, &newcluster, NULL);
          if (error)
                  goto bad2;
  
          bzero(&ndirent, sizeof(ndirent));
          ndirent.de_pmp = pmp;
          ndirent.de_flag = DE_ACCESS | DE_CREATE | DE_UPDATE;
          getnanotime(&ts);
          DETIMES(&ndirent, &ts, &ts, &ts);
  
          /*
           * Now fill the cluster with the "." and ".." entries. And write
           * the cluster to disk.  This way it is there for the parent
           * directory to be pointing at if there were a crash.
           */
          bn = cntobn(pmp, newcluster);
          /* always succeeds */
          bp = getblk(pmp->pm_devvp, bn, pmp->pm_bpcluster, 0, INFSLP);
          bzero(bp->b_data, pmp->pm_bpcluster);
          bcopy(&dosdirtemplate, bp->b_data, sizeof dosdirtemplate);
          denp = (struct direntry *)bp->b_data;
          putushort(denp[0].deStartCluster, newcluster);
          putushort(denp[0].deCDate, ndirent.de_CDate);
          putushort(denp[0].deCTime, ndirent.de_CTime);
          denp[0].deCTimeHundredth = ndirent.de_CTimeHundredth;
          putushort(denp[0].deADate, ndirent.de_ADate);
          putushort(denp[0].deMDate, ndirent.de_MDate);
          putushort(denp[0].deMTime, ndirent.de_MTime);
          pcl = pdep->de_StartCluster;
          if (FAT32(pmp) && pcl == pmp->pm_rootdirblk)
                  pcl = 0;
          putushort(denp[1].deStartCluster, pcl);
          putushort(denp[1].deCDate, ndirent.de_CDate);
          putushort(denp[1].deCTime, ndirent.de_CTime);
          denp[1].deCTimeHundredth = ndirent.de_CTimeHundredth;
          putushort(denp[1].deADate, ndirent.de_ADate);
          putushort(denp[1].deMDate, ndirent.de_MDate);
          putushort(denp[1].deMTime, ndirent.de_MTime);
          if (FAT32(pmp)) {
                  putushort(denp[0].deHighClust, newcluster >> 16);
                  putushort(denp[1].deHighClust, pdep->de_StartCluster >> 16);
          }
  
          if ((error = bwrite(bp)) != 0)
                  goto bad;
  
          /*
           * Now build up a directory entry pointing to the newly allocated
           * cluster.  This will be written to an empty slot in the parent
           * directory.
           */
  #ifdef DIAGNOSTIC
          if ((cnp->cn_flags & HASBUF) == 0)
                  panic("msdosfs_mkdir: no name");
  #endif
          if ((error = uniqdosname(pdep, cnp, ndirent.de_Name)) != 0)
                  goto bad;
  
          ndirent.de_Attributes = ATTR_DIRECTORY;
          ndirent.de_StartCluster = newcluster;
          ndirent.de_FileSize = 0;
          ndirent.de_dev = pdep->de_dev;
          ndirent.de_devvp = pdep->de_devvp;
          if ((error = createde(&ndirent, pdep, &dep, cnp)) != 0)
                  goto bad;
          if ((cnp->cn_flags & SAVESTART) == 0)
                  pool_put(&namei_pool, cnp->cn_pnbuf);
          VN_KNOTE(ap->a_dvp, NOTE_WRITE | NOTE_LINK);
          vput(ap->a_dvp);
          *ap->a_vpp = DETOV(dep);
          return (0);
  
  bad:
          clusterfree(pmp, newcluster, NULL);
  bad2:
          pool_put(&namei_pool, cnp->cn_pnbuf);
          vput(ap->a_dvp);
          return (error);
  }
  
  int
  msdosfs_rmdir(void *v)
  {
          struct vop_rmdir_args *ap = v;
          struct vnode *vp = ap->a_vp;
          struct vnode *dvp = ap->a_dvp;
          struct componentname *cnp = ap->a_cnp;
          struct denode *ip, *dp;
          int error;
  
          ip = VTODE(vp);
          dp = VTODE(dvp);
          /*
           * Verify the directory is empty (and valid).
           * (Rmdir ".." won't be valid since
           *  ".." will contain a reference to
           *  the current directory and thus be
           *  non-empty.)
           */
          error = 0;
          if (!dosdirempty(ip) || ip->de_flag & DE_RENAME) {
                  error = ENOTEMPTY;
                  goto out;
          }
  
          VN_KNOTE(dvp, NOTE_WRITE | NOTE_LINK);
  
          /*
           * Delete the entry from the directory.  For dos filesystems this
           * gets rid of the directory entry on disk, the in memory copy
           * still exists but the de_refcnt is <= 0.  This prevents it from
           * being found by deget().  When the vput() on dep is done we give
           * up access and eventually msdosfs_reclaim() will be called which
           * will remove it from the denode cache.
           */
          if ((error = removede(dp, ip)) != 0)
                  goto out;
          /*
           * This is where we decrement the link count in the parent
           * directory.  Since dos filesystems don't do this we just purge
           * the name cache and let go of the parent directory denode.
           */
          cache_purge(dvp);
          vput(dvp);
          dvp = NULL;
          /*
           * Truncate the directory that is being deleted.
           */
          error = detrunc(ip, (uint32_t)0, IO_SYNC, cnp->cn_cred, cnp->cn_proc);
          cache_purge(vp);
  out:
          if (dvp)
                  vput(dvp);
          VN_KNOTE(vp, NOTE_DELETE);
          vput(vp);
          return (error);
  }
  
  /*
   * DOS filesystems don't know what symlinks are.
   */
  int
  msdosfs_symlink(void *v)
  {
          struct vop_symlink_args *ap = v;
  
          VOP_ABORTOP(ap->a_dvp, ap->a_cnp);
          vput(ap->a_dvp);
          return (EOPNOTSUPP);
  }
  
  int
  msdosfs_readdir(void *v)
  {
          struct vop_readdir_args *ap = v;
          int error = 0;
          int diff;
          long n;
          int blsize;
          long on;
          long lost;
          long count;
          uint32_t dirsperblk;
          uint32_t cn, lbn;
          uint32_t fileno;
          long bias = 0;
          daddr_t bn;
          struct buf *bp;
          struct denode *dep = VTODE(ap->a_vp);
          struct msdosfsmount *pmp = dep->de_pmp;
          struct direntry *dentp;
          struct dirent dirbuf;
          struct uio *uio = ap->a_uio;
          off_t offset, wlast = -1;
          int chksum = -1;
  
  #ifdef MSDOSFS_DEBUG
          printf("msdosfs_readdir(): vp %p, uio %p, cred %p, eofflagp %p\n",
              ap->a_vp, uio, ap->a_cred, ap->a_eofflag);
  #endif
  
          /*
           * msdosfs_readdir() won't operate properly on regular files since
           * it does i/o only with the filesystem vnode, and hence can
           * retrieve the wrong block from the buffer cache for a plain file.
           * So, fail attempts to readdir() on a plain file.
           */
          if ((dep->de_Attributes & ATTR_DIRECTORY) == 0)
                  return (ENOTDIR);
  
          /*
           * To be safe, initialize dirbuf
           */
          bzero(&dirbuf, sizeof(dirbuf));
  
          /*
           * If the user buffer is smaller than the size of one dos directory
           * entry or the file offset is not a multiple of the size of a
           * directory entry, then we fail the read.
           */
          count = uio->uio_resid & ~(sizeof(struct direntry) - 1);
          offset = uio->uio_offset;
          if (count < sizeof(struct direntry) ||
              (offset & (sizeof(struct direntry) - 1)))
                  return (EINVAL);
          lost = uio->uio_resid - count;
          uio->uio_resid = count;
  
          dirsperblk = pmp->pm_BytesPerSec / sizeof(struct direntry);
  
          /*
           * If they are reading from the root directory then, we simulate
           * the . and .. entries since these don't exist in the root
           * directory.  We also set the offset bias to make up for having to
           * simulate these entries. By this I mean that at file offset 64 we
           * read the first entry in the root directory that lives on disk.
           */
          if (dep->de_StartCluster == MSDOSFSROOT
              || (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)) {
  #if 0
                  printf("msdosfs_readdir(): going after . or .. in root dir, offset %d\n",
                      offset);
  #endif
                  bias = 2 * sizeof(struct direntry);
                  if (offset < bias) {
                          for (n = (int)offset / sizeof(struct direntry);
                               n < 2; n++) {
                                  if (FAT32(pmp))
                                          dirbuf.d_fileno = pmp->pm_rootdirblk;
                                  else
                                          dirbuf.d_fileno = 1;
                                  dirbuf.d_type = DT_DIR;
                                  switch (n) {
                                  case 0:
                                          dirbuf.d_namlen = 1;
                                          strlcpy(dirbuf.d_name, ".",
                                              sizeof dirbuf.d_name);
                                          break;
                                  case 1:
                                          dirbuf.d_namlen = 2;
                                          strlcpy(dirbuf.d_name, "..",
                                              sizeof dirbuf.d_name);
                                          break;
                                  }
                                  dirbuf.d_reclen = DIRENT_SIZE(&dirbuf);
                                  dirbuf.d_off = offset +
                                      sizeof(struct direntry);
                                  if (uio->uio_resid < dirbuf.d_reclen)
                                          goto out;
                                  error = uiomove(&dirbuf, dirbuf.d_reclen, uio);
                                  if (error)
                                          goto out;
                                  offset = dirbuf.d_off;
                          }
                  }
          }
  
          while (uio->uio_resid > 0) {
                  lbn = de_cluster(pmp, offset - bias);
                  on = (offset - bias) & pmp->pm_crbomask;
                  n = min(pmp->pm_bpcluster - on, uio->uio_resid);
                  diff = dep->de_FileSize - (offset - bias);
                  if (diff <= 0)
                          break;
                  n = min(n, diff);
                  if ((error = pcbmap(dep, lbn, &bn, &cn, &blsize)) != 0)
                          break;
                  error = bread(pmp->pm_devvp, bn, blsize, &bp);
                  if (error) {
                          brelse(bp);
                          return (error);
                  }
                  n = min(n, blsize - bp->b_resid);
  
                  /*
                   * Convert from dos directory entries to fs-independent
                   * directory entries.
                   */
                  for (dentp = (struct direntry *)(bp->b_data + on);
                       (char *)dentp < bp->b_data + on + n;
                       dentp++, offset += sizeof(struct direntry)) {
  #if 0
                          printf("rd: dentp %08x prev %08x crnt %08x deName %02x attr %02x\n",
                              dentp, prev, crnt, dentp->deName[0], dentp->deAttributes);
  #endif
                          /*
                           * If this is an unused entry, we can stop.
                           */
                          if (dentp->deName[0] == SLOT_EMPTY) {
                                  brelse(bp);
                                  goto out;
                          }
                          /*
                           * Skip deleted entries.
                           */
                          if (dentp->deName[0] == SLOT_DELETED) {
                                  chksum = -1;
                                  wlast = -1;
                                  continue;
                          }
  
                          /*
                           * Handle Win95 long directory entries
                           */
                          if (dentp->deAttributes == ATTR_WIN95) {
                                  struct winentry *wep;
                                  if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
                                          continue;
                                  wep = (struct winentry *)dentp;
                                  chksum = win2unixfn(wep, &dirbuf, chksum);
                                  if (wep->weCnt & WIN_LAST)
                                          wlast = offset;
                                  continue;
                          }
  
                          /*
                           * Skip volume labels
                           */
                          if (dentp->deAttributes & ATTR_VOLUME) {
                                  chksum = -1;
                                  wlast = -1;
                                  continue;
                          }
  
                          /*
                           * This computation of d_fileno must match
                           * the computation of va_fileid in
                           * msdosfs_getattr.
                           */
                          fileno = getushort(dentp->deStartCluster);
                          if (FAT32(pmp))
                              fileno |= getushort(dentp->deHighClust) << 16;
  
                          if (dentp->deAttributes & ATTR_DIRECTORY) {
                                  /* Special-case root */
                                  if (fileno == MSDOSFSROOT)  {
                                          fileno = FAT32(pmp) ?
                                              pmp->pm_rootdirblk : 1;
                                  }
  
                                  dirbuf.d_fileno = fileno;
                                  dirbuf.d_type = DT_DIR;
                          } else {
                                  if (getulong(dentp->deFileSize) == 0) {
                                          uint64_t fileno64;
  
                                          fileno64 = (cn == MSDOSFSROOT) ?
                                              roottobn(pmp, 0) : cntobn(pmp, cn);
  
                                          fileno64 *= dirsperblk;
                                          fileno64 += dentp -
                                              (struct direntry *)bp->b_data;
  
                                          fileno = fileidhash(fileno64);
                                  }
  
                                  dirbuf.d_fileno = fileno;
                                  dirbuf.d_type = DT_REG;
                          }
  
                          if (chksum != winChksum(dentp->deName))
                                  dirbuf.d_namlen = dos2unixfn(dentp->deName,
                                      (u_char *)dirbuf.d_name,
                                      pmp->pm_flags & MSDOSFSMNT_SHORTNAME);
                          else
                                  dirbuf.d_name[dirbuf.d_namlen] = 0;
                          chksum = -1;
                          dirbuf.d_reclen = DIRENT_SIZE(&dirbuf);
                          dirbuf.d_off = offset + sizeof(struct direntry);
                          if (uio->uio_resid < dirbuf.d_reclen) {
                                  brelse(bp);
                                  /* Remember long-name offset. */
                                  if (wlast != -1)
                                          offset = wlast;
                                  goto out;
                          }
                          wlast = -1;
                          error = uiomove(&dirbuf, dirbuf.d_reclen, uio);
                          if (error) {
                                  brelse(bp);
                                  goto out;
                          }
                  }
                  brelse(bp);
          }
  
  out:
          uio->uio_offset = offset;
          uio->uio_resid += lost;
          if (dep->de_FileSize - (offset - bias) <= 0)
                  *ap->a_eofflag = 1;
          else
                  *ap->a_eofflag = 0;
          return (error);
  }
  
  /*
   * DOS filesystems don't know what symlinks are.
   */
  int
  msdosfs_readlink(void *v)
  {
  #if 0
          struct vop_readlink_args /* {
                  struct vnode *a_vp;
                  struct uio *a_uio;
                  struct ucred *a_cred;
          } */ *ap;
  #endif
  
          return (EINVAL);
  }
  
  int
  msdosfs_lock(void *v)
  {
          struct vop_lock_args *ap = v;
          struct vnode *vp = ap->a_vp;
  
          return rrw_enter(&VTODE(vp)->de_lock, ap->a_flags & LK_RWFLAGS);
  }
  
  int
  msdosfs_unlock(void *v)
  {
          struct vop_unlock_args *ap = v;
          struct vnode *vp = ap->a_vp;
  
          rrw_exit(&VTODE(vp)->de_lock);
          return 0;
  }
  
  int
  msdosfs_islocked(void *v)
  {
          struct vop_islocked_args *ap = v;
  
          return rrw_status(&VTODE(ap->a_vp)->de_lock);
  }
  
  /*
   * vp  - address of vnode file the file
   * bn  - which cluster we are interested in mapping to a filesystem block number
   * vpp - returns the vnode for the block special file holding the filesystem
   *       containing the file of interest
   * bnp - address of where to return the filesystem relative block number
   */
  int
  msdosfs_bmap(void *v)
  {
          struct vop_bmap_args *ap = v;
          struct denode *dep = VTODE(ap->a_vp);
          uint32_t cn;
  
          if (ap->a_vpp != NULL)
                  *ap->a_vpp = dep->de_devvp;
          if (ap->a_bnp == NULL)
                  return (0);
  
          cn = ap->a_bn;
          if (cn != ap->a_bn)
                  return (EFBIG);
  
          return (msdosfs_bmaparray(ap->a_vp, cn, ap->a_bnp, ap->a_runp));
  }
  
  int
  msdosfs_bmaparray(struct vnode *vp, uint32_t cn, daddr_t *bnp, int *runp)
  {
          struct denode *dep = VTODE(vp);
          struct msdosfsmount *pmp = dep->de_pmp;
          struct mount *mp;
          int error, maxrun = 0, run;
          daddr_t runbn;
  
          mp = vp->v_mount;
  
          if (runp) {
                  /*
                   * XXX
                   * If MAXBSIZE is the largest transfer the disks can handle,
                   * we probably want maxrun to be 1 block less so that we
                   * don't create a block larger than the device can handle.
                   */
                  *runp = 0;
                  maxrun = min(MAXBSIZE / mp->mnt_stat.f_iosize - 1,
                      pmp->pm_maxcluster - cn);
          }
  
          if ((error = pcbmap(dep, cn, bnp, 0, 0)) != 0)
                  return (error);
  
          for (run = 1; run <= maxrun; run++) {
                  error = pcbmap(dep, cn + run, &runbn, 0, 0);
                  if (error != 0 || (runbn != *bnp + de_cn2bn(pmp, run)))
                          break;
          }
  
          if (runp)
                  *runp = run - 1;
  
          return (0);
  }
  
  int
  msdosfs_strategy(void *v)
  {
          struct vop_strategy_args *ap = v;
          struct buf *bp = ap->a_bp;
          struct denode *dep = VTODE(bp->b_vp);
          struct vnode *vp;
          int error = 0;
          int s;
  
          if (bp->b_vp->v_type == VBLK || bp->b_vp->v_type == VCHR)
                  panic("msdosfs_strategy: spec");
          /*
           * If we don't already know the filesystem relative block number
           * then get it using pcbmap().  If pcbmap() returns the block
           * number as -1 then we've got a hole in the file.  DOS filesystems
           * don't allow files with holes, so we shouldn't ever see this.
           */
          if (bp->b_blkno == bp->b_lblkno) {
                  error = pcbmap(dep, bp->b_lblkno, &bp->b_blkno, 0, 0);
                  if (error)
                          bp->b_blkno = -1;
                  if (bp->b_blkno == -1)
                          clrbuf(bp);
          }
          if (bp->b_blkno == -1) {
                  s = splbio();
                  biodone(bp);
                  splx(s);
                  return (error);
          }
  
          /*
           * Read/write the block from/to the disk that contains the desired
           * file block.
           */
  
          vp = dep->de_devvp;
          bp->b_dev = vp->v_rdev;
          VOP_STRATEGY(vp, bp);
          return (0);
  }
  
  int
  msdosfs_print(void *v)
  {
          struct vop_print_args *ap = v;
          struct denode *dep = VTODE(ap->a_vp);
  
          printf(
              "tag VT_MSDOSFS, startcluster %u, dircluster %u, diroffset %u ",
              dep->de_StartCluster, dep->de_dirclust, dep->de_diroffset);
          printf(" dev %d, %d, %s\n",
              major(dep->de_dev), minor(dep->de_dev),
              VOP_ISLOCKED(ap->a_vp) ? "(LOCKED)" : "");
  #ifdef DIAGNOSTIC
          printf("\n");
  #endif
  
          return (0);
  }
  
  int
  msdosfs_advlock(void *v)
  {
          struct vop_advlock_args *ap = v;
          struct denode *dep = VTODE(ap->a_vp);
  
          return (lf_advlock(&dep->de_lockf, dep->de_FileSize, ap->a_id, ap->a_op,
              ap->a_fl, ap->a_flags));
  }
  
  int
  msdosfs_pathconf(void *v)
  {
          struct vop_pathconf_args *ap = v;
          struct msdosfsmount *pmp = VTODE(ap->a_vp)->de_pmp;
          int error = 0;
  
          switch (ap->a_name) {
          case _PC_LINK_MAX:
                  *ap->a_retval = 1;
                  break;
          case _PC_NAME_MAX:
                  *ap->a_retval = pmp->pm_flags & MSDOSFSMNT_LONGNAME ? WIN_MAXLEN : 12;
                  break;
          case _PC_CHOWN_RESTRICTED:
                  *ap->a_retval = 1;
                  break;
          case _PC_NO_TRUNC:
                  *ap->a_retval = 0;
                  break;
          case _PC_TIMESTAMP_RESOLUTION:
                  *ap->a_retval = 2000000000;     /* 2 billion nanoseconds */
                  break;
          default:
                  error = EINVAL;
                  break;
          }
  
          return (error);
  }
  
  /*
   * Thomas Wang's hash function, severely hacked to always set the high
   * bit on the number it returns (so no longer a proper hash function).
   */
  static uint32_t
  fileidhash(uint64_t fileid)
  {
          uint64_t c1 = 0x6e5ea73858134343LL;
          uint64_t c2 = 0xb34e8f99a2ec9ef5LL;
  
          /*
           * We now have the original fileid value, as 64-bit value.
           * We need to reduce it to 32-bits, with the top bit set.
           */
          fileid ^= ((c1 ^ fileid) >> 32);
          fileid *= c1;
          fileid ^= ((c2 ^ fileid) >> 31);
          fileid *= c2;
          fileid ^= ((c1 ^ fileid) >> 32);
  
          return (uint32_t)(fileid | 0x80000000);
  }
  
  /* Global vfs data structures for msdosfs */
  const struct vops msdosfs_vops = {
          .vop_lookup     = msdosfs_lookup,
          .vop_create     = msdosfs_create,
          .vop_mknod      = msdosfs_mknod,
          .vop_open       = msdosfs_open,
          .vop_close      = msdosfs_close,
          .vop_access     = msdosfs_access,
          .vop_getattr    = msdosfs_getattr,
          .vop_setattr    = msdosfs_setattr,
          .vop_read       = msdosfs_read,
          .vop_write      = msdosfs_write,
          .vop_ioctl      = msdosfs_ioctl,
          .vop_kqfilter   = msdosfs_kqfilter,
          .vop_fsync      = msdosfs_fsync,
          .vop_remove     = msdosfs_remove,
          .vop_link       = msdosfs_link,
          .vop_rename     = msdosfs_rename,
          .vop_mkdir      = msdosfs_mkdir,
          .vop_rmdir      = msdosfs_rmdir,
          .vop_symlink    = msdosfs_symlink,
          .vop_readdir    = msdosfs_readdir,
          .vop_readlink   = msdosfs_readlink,
          .vop_abortop    = vop_generic_abortop,
          .vop_inactive   = msdosfs_inactive,
          .vop_reclaim    = msdosfs_reclaim,
          .vop_lock       = msdosfs_lock,
          .vop_unlock     = msdosfs_unlock,
          .vop_bmap       = msdosfs_bmap,
          .vop_strategy   = msdosfs_strategy,
          .vop_print      = msdosfs_print,
          .vop_islocked   = msdosfs_islocked,
          .vop_pathconf   = msdosfs_pathconf,
          .vop_advlock    = msdosfs_advlock,
          .vop_bwrite     = vop_generic_bwrite,
          .vop_revoke     = vop_generic_revoke,
  };
  
  const struct filterops msdosfsread_filtops = {
          .f_flags        = FILTEROP_ISFD,
          .f_attach       = NULL,
          .f_detach       = filt_msdosfsdetach,
          .f_event        = filt_msdosfsread,
  };
  
  const struct filterops msdosfswrite_filtops = {
          .f_flags        = FILTEROP_ISFD,
          .f_attach       = NULL,
          .f_detach       = filt_msdosfsdetach,
          .f_event        = filt_msdosfswrite,
  };
  
  const struct filterops msdosfsvnode_filtops = {
          .f_flags        = FILTEROP_ISFD,
          .f_attach       = NULL,
          .f_detach       = filt_msdosfsdetach,
          .f_event        = filt_msdosfsvnode,
  };
  
  int
  msdosfs_kqfilter(void *v)
  {
          struct vop_kqfilter_args *ap = v;
          struct vnode *vp = ap->a_vp;
          struct knote *kn = ap->a_kn;
  
          switch (kn->kn_filter) {
          case EVFILT_READ:
                  kn->kn_fop = &msdosfsread_filtops;
                  break;
          case EVFILT_WRITE:
                  kn->kn_fop = &msdosfswrite_filtops;
                  break;
          case EVFILT_VNODE:
                  kn->kn_fop = &msdosfsvnode_filtops;
                  break;
          default:
                  return (EINVAL);
          }
  
          kn->kn_hook = (caddr_t)vp;
  
          klist_insert_locked(&vp->v_selectinfo.si_note, kn);
  
          return (0);
  }
  
  void
  filt_msdosfsdetach(struct knote *kn)
  {
          struct vnode *vp = (struct vnode *)kn->kn_hook;
  
          klist_remove_locked(&vp->v_selectinfo.si_note, kn);
  }
  
  int
  filt_msdosfsread(struct knote *kn, long hint)
  {
          struct vnode *vp = (struct vnode *)kn->kn_hook;
          struct denode *dep = VTODE(vp);
  
          /*
           * filesystem is gone, so set the EOF flag and schedule
           * the knote for deletion.
           */
          if (hint == NOTE_REVOKE) {
                  kn->kn_flags |= (EV_EOF | EV_ONESHOT);
                  return (1);
          }
  
          kn->kn_data = dep->de_FileSize - foffset(kn->kn_fp);
          if (kn->kn_data == 0 && kn->kn_sfflags & NOTE_EOF) {
                  kn->kn_fflags |= NOTE_EOF;
                  return (1);
          }
  
          if (kn->kn_flags & (__EV_POLL | __EV_SELECT))
                  return (1);
  
          return (kn->kn_data != 0);
  }
  
  int
  filt_msdosfswrite(struct knote *kn, long hint)
  {
          /*
           * filesystem is gone, so set the EOF flag and schedule
           * the knote for deletion.
           */
          if (hint == NOTE_REVOKE) {
                  kn->kn_flags |= (EV_EOF | EV_ONESHOT);
                  return (1);
          }
  
          kn->kn_data = 0;
          return (1);
  }
  
  int
  filt_msdosfsvnode(struct knote *kn, long hint)
  {
          if (kn->kn_sfflags & hint)
                  kn->kn_fflags |= hint;
          if (hint == NOTE_REVOKE) {
                  kn->kn_flags |= EV_EOF;
                  return (1);
          }
          return (kn->kn_fflags != 0);
  }

Cache object: 67e11a8d2764266c7cfe392459c875c6