The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/msdosfs/msdosfs_lookup.c

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    1 /* $FreeBSD$ */
    2 /*      $NetBSD: msdosfs_lookup.c,v 1.37 1997/11/17 15:36:54 ws Exp $   */
    3 
    4 /*-
    5  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
    6  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
    7  * All rights reserved.
    8  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by TooLs GmbH.
   21  * 4. The name of TooLs GmbH may not be used to endorse or promote products
   22  *    derived from this software without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
   25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   27  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   29  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   30  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   31  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   32  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   33  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   34  */
   35 /*-
   36  * Written by Paul Popelka (paulp@uts.amdahl.com)
   37  *
   38  * You can do anything you want with this software, just don't say you wrote
   39  * it, and don't remove this notice.
   40  *
   41  * This software is provided "as is".
   42  *
   43  * The author supplies this software to be publicly redistributed on the
   44  * understanding that the author is not responsible for the correct
   45  * functioning of this software in any circumstances and is not liable for
   46  * any damages caused by this software.
   47  *
   48  * October 1992
   49  */
   50 
   51 #include <sys/param.h>
   52 #include <sys/systm.h>
   53 #include <sys/namei.h>
   54 #include <sys/bio.h>
   55 #include <sys/buf.h>
   56 #include <sys/vnode.h>
   57 #include <sys/mount.h>
   58 
   59 #include <fs/msdosfs/bpb.h>
   60 #include <fs/msdosfs/msdosfsmount.h>
   61 #include <fs/msdosfs/direntry.h>
   62 #include <fs/msdosfs/denode.h>
   63 #include <fs/msdosfs/fat.h>
   64 
   65 /*
   66  * When we search a directory the blocks containing directory entries are
   67  * read and examined.  The directory entries contain information that would
   68  * normally be in the inode of a unix filesystem.  This means that some of
   69  * a directory's contents may also be in memory resident denodes (sort of
   70  * an inode).  This can cause problems if we are searching while some other
   71  * process is modifying a directory.  To prevent one process from accessing
   72  * incompletely modified directory information we depend upon being the
   73  * sole owner of a directory block.  bread/brelse provide this service.
   74  * This being the case, when a process modifies a directory it must first
   75  * acquire the disk block that contains the directory entry to be modified.
   76  * Then update the disk block and the denode, and then write the disk block
   77  * out to disk.  This way disk blocks containing directory entries and in
   78  * memory denode's will be in synch.
   79  */
   80 int
   81 msdosfs_lookup(ap)
   82         struct vop_cachedlookup_args /* {
   83                 struct vnode *a_dvp;
   84                 struct vnode **a_vpp;
   85                 struct componentname *a_cnp;
   86         } */ *ap;
   87 {
   88         struct vnode *vdp = ap->a_dvp;
   89         struct vnode **vpp = ap->a_vpp;
   90         struct componentname *cnp = ap->a_cnp;
   91         daddr_t bn;
   92         int error;
   93         int lockparent;
   94         int wantparent;
   95         int slotcount;
   96         int slotoffset = 0;
   97         int frcn;
   98         u_long cluster;
   99         int blkoff;
  100         int diroff;
  101         int blsize;
  102         int isadir;             /* ~0 if found direntry is a directory   */
  103         u_long scn;             /* starting cluster number               */
  104         struct vnode *pdp;
  105         struct denode *dp;
  106         struct denode *tdp;
  107         struct msdosfsmount *pmp;
  108         struct buf *bp = 0;
  109         struct direntry *dep = NULL;
  110         u_char dosfilename[12];
  111         int flags = cnp->cn_flags;
  112         int nameiop = cnp->cn_nameiop;
  113         struct thread *td = cnp->cn_thread;
  114         int unlen;
  115 
  116         int wincnt = 1;
  117         int chksum = -1, chksum_ok;
  118         int olddos = 1;
  119         cnp->cn_flags &= ~PDIRUNLOCK;
  120 
  121 #ifdef MSDOSFS_DEBUG
  122         printf("msdosfs_lookup(): looking for %s\n", cnp->cn_nameptr);
  123 #endif
  124         dp = VTODE(vdp);
  125         pmp = dp->de_pmp;
  126         *vpp = NULL;
  127         lockparent = flags & LOCKPARENT;
  128         wantparent = flags & (LOCKPARENT | WANTPARENT);
  129 #ifdef MSDOSFS_DEBUG
  130         printf("msdosfs_lookup(): vdp %p, dp %p, Attr %02x\n",
  131             vdp, dp, dp->de_Attributes);
  132 #endif
  133 
  134         /*
  135          * If they are going after the . or .. entry in the root directory,
  136          * they won't find it.  DOS filesystems don't have them in the root
  137          * directory.  So, we fake it. deget() is in on this scam too.
  138          */
  139         if ((vdp->v_vflag & VV_ROOT) && cnp->cn_nameptr[0] == '.' &&
  140             (cnp->cn_namelen == 1 ||
  141                 (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.'))) {
  142                 isadir = ATTR_DIRECTORY;
  143                 scn = MSDOSFSROOT;
  144 #ifdef MSDOSFS_DEBUG
  145                 printf("msdosfs_lookup(): looking for . or .. in root directory\n");
  146 #endif
  147                 cluster = MSDOSFSROOT;
  148                 blkoff = MSDOSFSROOT_OFS;
  149                 goto foundroot;
  150         }
  151 
  152         switch (unix2dosfn((const u_char *)cnp->cn_nameptr, dosfilename,
  153             cnp->cn_namelen, 0, pmp)) {
  154         case 0:
  155                 return (EINVAL);
  156         case 1:
  157                 break;
  158         case 2:
  159                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  160                     cnp->cn_namelen, pmp) + 1;
  161                 break;
  162         case 3:
  163                 olddos = 0;
  164                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  165                     cnp->cn_namelen, pmp) + 1;
  166                 break;
  167         }
  168         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME) {
  169                 wincnt = 1;
  170                 olddos = 1;
  171         }
  172         unlen = winLenFixup(cnp->cn_nameptr, cnp->cn_namelen);
  173 
  174         /*
  175          * Suppress search for slots unless creating
  176          * file and at end of pathname, in which case
  177          * we watch for a place to put the new file in
  178          * case it doesn't already exist.
  179          */
  180         slotcount = wincnt;
  181         if ((nameiop == CREATE || nameiop == RENAME) &&
  182             (flags & ISLASTCN))
  183                 slotcount = 0;
  184 
  185 #ifdef MSDOSFS_DEBUG
  186         printf("msdosfs_lookup(): dos version of filename %s, length %ld\n",
  187             dosfilename, cnp->cn_namelen);
  188 #endif
  189         /*
  190          * Search the directory pointed at by vdp for the name pointed at
  191          * by cnp->cn_nameptr.
  192          */
  193         tdp = NULL;
  194         mbnambuf_init();
  195         /*
  196          * The outer loop ranges over the clusters that make up the
  197          * directory.  Note that the root directory is different from all
  198          * other directories.  It has a fixed number of blocks that are not
  199          * part of the pool of allocatable clusters.  So, we treat it a
  200          * little differently. The root directory starts at "cluster" 0.
  201          */
  202         diroff = 0;
  203         for (frcn = 0;; frcn++) {
  204                 error = pcbmap(dp, frcn, &bn, &cluster, &blsize);
  205                 if (error) {
  206                         if (error == E2BIG)
  207                                 break;
  208                         return (error);
  209                 }
  210                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  211                 if (error) {
  212                         brelse(bp);
  213                         return (error);
  214                 }
  215                 for (blkoff = 0; blkoff < blsize;
  216                      blkoff += sizeof(struct direntry),
  217                      diroff += sizeof(struct direntry)) {
  218                         dep = (struct direntry *)(bp->b_data + blkoff);
  219                         /*
  220                          * If the slot is empty and we are still looking
  221                          * for an empty then remember this one.  If the
  222                          * slot is not empty then check to see if it
  223                          * matches what we are looking for.  If the slot
  224                          * has never been filled with anything, then the
  225                          * remainder of the directory has never been used,
  226                          * so there is no point in searching it.
  227                          */
  228                         if (dep->deName[0] == SLOT_EMPTY ||
  229                             dep->deName[0] == SLOT_DELETED) {
  230                                 /*
  231                                  * Drop memory of previous long matches
  232                                  */
  233                                 chksum = -1;
  234                                 mbnambuf_init();
  235 
  236                                 if (slotcount < wincnt) {
  237                                         slotcount++;
  238                                         slotoffset = diroff;
  239                                 }
  240                                 if (dep->deName[0] == SLOT_EMPTY) {
  241                                         brelse(bp);
  242                                         goto notfound;
  243                                 }
  244                         } else {
  245                                 /*
  246                                  * If there wasn't enough space for our winentries,
  247                                  * forget about the empty space
  248                                  */
  249                                 if (slotcount < wincnt)
  250                                         slotcount = 0;
  251 
  252                                 /*
  253                                  * Check for Win95 long filename entry
  254                                  */
  255                                 if (dep->deAttributes == ATTR_WIN95) {
  256                                         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
  257                                                 continue;
  258 
  259                                         chksum = win2unixfn((struct winentry *)dep,
  260                                                             chksum,
  261                                                             pmp);
  262                                         continue;
  263                                 }
  264 
  265                                 chksum = winChkName((const u_char *)cnp->cn_nameptr,
  266                                                     unlen,
  267                                                     chksum,
  268                                                     pmp);
  269                                 if (chksum == -2) {
  270                                         chksum = -1;
  271                                         continue;
  272                                 }
  273 
  274                                 /*
  275                                  * Ignore volume labels (anywhere, not just
  276                                  * the root directory).
  277                                  */
  278                                 if (dep->deAttributes & ATTR_VOLUME) {
  279                                         chksum = -1;
  280                                         continue;
  281                                 }
  282 
  283                                 /*
  284                                  * Check for a checksum or name match
  285                                  */
  286                                 chksum_ok = (chksum == winChksum(dep->deName));
  287                                 if (!chksum_ok
  288                                     && (!olddos || bcmp(dosfilename, dep->deName, 11))) {
  289                                         chksum = -1;
  290                                         continue;
  291                                 }
  292 #ifdef MSDOSFS_DEBUG
  293                                 printf("msdosfs_lookup(): match blkoff %d, diroff %d\n",
  294                                     blkoff, diroff);
  295 #endif
  296                                 /*
  297                                  * Remember where this directory
  298                                  * entry came from for whoever did
  299                                  * this lookup.
  300                                  */
  301                                 dp->de_fndoffset = diroff;
  302                                 if (chksum_ok && nameiop == RENAME) {
  303                                         /*
  304                                          * Target had correct long name
  305                                          * directory entries, reuse them
  306                                          * as needed.
  307                                          */
  308                                         dp->de_fndcnt = wincnt - 1;
  309                                 } else {
  310                                         /*
  311                                          * Long name directory entries
  312                                          * not present or corrupt, can only
  313                                          * reuse dos directory entry.
  314                                          */
  315                                         dp->de_fndcnt = 0;
  316                                 }
  317 
  318                                 goto found;
  319                         }
  320                 }       /* for (blkoff = 0; .... */
  321                 /*
  322                  * Release the buffer holding the directory cluster just
  323                  * searched.
  324                  */
  325                 brelse(bp);
  326         }       /* for (frcn = 0; ; frcn++) */
  327 
  328 notfound:
  329         /*
  330          * We hold no disk buffers at this point.
  331          */
  332 
  333         /*
  334          * Fixup the slot description to point to the place where
  335          * we might put the new DOS direntry (putting the Win95
  336          * long name entries before that)
  337          */
  338         if (!slotcount) {
  339                 slotcount = 1;
  340                 slotoffset = diroff;
  341         }
  342         if (wincnt > slotcount)
  343                 slotoffset += sizeof(struct direntry) * (wincnt - slotcount);
  344 
  345         /*
  346          * If we get here we didn't find the entry we were looking for. But
  347          * that's ok if we are creating or renaming and are at the end of
  348          * the pathname and the directory hasn't been removed.
  349          */
  350 #ifdef MSDOSFS_DEBUG
  351         printf("msdosfs_lookup(): op %d, refcnt %ld\n",
  352             nameiop, dp->de_refcnt);
  353         printf("               slotcount %d, slotoffset %d\n",
  354                slotcount, slotoffset);
  355 #endif
  356         if ((nameiop == CREATE || nameiop == RENAME) &&
  357             (flags & ISLASTCN) && dp->de_refcnt != 0) {
  358                 /*
  359                  * Access for write is interpreted as allowing
  360                  * creation of files in the directory.
  361                  */
  362                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  363                 if (error)
  364                         return (error);
  365                 /*
  366                  * Return an indication of where the new directory
  367                  * entry should be put.
  368                  */
  369                 dp->de_fndoffset = slotoffset;
  370                 dp->de_fndcnt = wincnt - 1;
  371 
  372                 /*
  373                  * We return with the directory locked, so that
  374                  * the parameters we set up above will still be
  375                  * valid if we actually decide to do a direnter().
  376                  * We return ni_vp == NULL to indicate that the entry
  377                  * does not currently exist; we leave a pointer to
  378                  * the (locked) directory inode in ndp->ni_dvp.
  379                  * The pathname buffer is saved so that the name
  380                  * can be obtained later.
  381                  *
  382                  * NB - if the directory is unlocked, then this
  383                  * information cannot be used.
  384                  */
  385                 cnp->cn_flags |= SAVENAME;
  386                 if (!lockparent) {
  387                         VOP_UNLOCK(vdp, 0, td);
  388                         cnp->cn_flags |= PDIRUNLOCK;
  389                 }
  390                 return (EJUSTRETURN);
  391         }
  392         /*
  393          * Insert name into cache (as non-existent) if appropriate.
  394          */
  395         if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
  396                 cache_enter(vdp, *vpp, cnp);
  397         return (ENOENT);
  398 
  399 found:
  400         /*
  401          * NOTE:  We still have the buffer with matched directory entry at
  402          * this point.
  403          */
  404         isadir = dep->deAttributes & ATTR_DIRECTORY;
  405         scn = getushort(dep->deStartCluster);
  406         if (FAT32(pmp)) {
  407                 scn |= getushort(dep->deHighClust) << 16;
  408                 if (scn == pmp->pm_rootdirblk) {
  409                         /*
  410                          * There should actually be 0 here.
  411                          * Just ignore the error.
  412                          */
  413                         scn = MSDOSFSROOT;
  414                 }
  415         }
  416 
  417         if (isadir) {
  418                 cluster = scn;
  419                 if (cluster == MSDOSFSROOT)
  420                         blkoff = MSDOSFSROOT_OFS;
  421                 else
  422                         blkoff = 0;
  423         } else if (cluster == MSDOSFSROOT)
  424                 blkoff = diroff;
  425 
  426         /*
  427          * Now release buf to allow deget to read the entry again.
  428          * Reserving it here and giving it to deget could result
  429          * in a deadlock.
  430          */
  431         brelse(bp);
  432         bp = 0;
  433         
  434 foundroot:
  435         /*
  436          * If we entered at foundroot, then we are looking for the . or ..
  437          * entry of the filesystems root directory.  isadir and scn were
  438          * setup before jumping here.  And, bp is already null.
  439          */
  440         if (FAT32(pmp) && scn == MSDOSFSROOT)
  441                 scn = pmp->pm_rootdirblk;
  442 
  443         /*
  444          * If deleting, and at end of pathname, return
  445          * parameters which can be used to remove file.
  446          * If the wantparent flag isn't set, we return only
  447          * the directory (in ndp->ni_dvp), otherwise we go
  448          * on and lock the inode, being careful with ".".
  449          */
  450         if (nameiop == DELETE && (flags & ISLASTCN)) {
  451                 /*
  452                  * Don't allow deleting the root.
  453                  */
  454                 if (blkoff == MSDOSFSROOT_OFS)
  455                         return EROFS;                           /* really? XXX */
  456 
  457                 /*
  458                  * Write access to directory required to delete files.
  459                  */
  460                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  461                 if (error)
  462                         return (error);
  463 
  464                 /*
  465                  * Return pointer to current entry in dp->i_offset.
  466                  * Save directory inode pointer in ndp->ni_dvp for dirremove().
  467                  */
  468                 if (dp->de_StartCluster == scn && isadir) {     /* "." */
  469                         VREF(vdp);
  470                         *vpp = vdp;
  471                         return (0);
  472                 }
  473                 error = deget(pmp, cluster, blkoff, &tdp);
  474                 if (error)
  475                         return (error);
  476                 *vpp = DETOV(tdp);
  477                 if (!lockparent) {
  478                         VOP_UNLOCK(vdp, 0, td);
  479                         cnp->cn_flags |= PDIRUNLOCK;
  480                 }
  481                 return (0);
  482         }
  483 
  484         /*
  485          * If rewriting (RENAME), return the inode and the
  486          * information required to rewrite the present directory
  487          * Must get inode of directory entry to verify it's a
  488          * regular file, or empty directory.
  489          */
  490         if (nameiop == RENAME && wantparent &&
  491             (flags & ISLASTCN)) {
  492                 if (blkoff == MSDOSFSROOT_OFS)
  493                         return EROFS;                           /* really? XXX */
  494 
  495                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  496                 if (error)
  497                         return (error);
  498 
  499                 /*
  500                  * Careful about locking second inode.
  501                  * This can only occur if the target is ".".
  502                  */
  503                 if (dp->de_StartCluster == scn && isadir)
  504                         return (EISDIR);
  505 
  506                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  507                         return (error);
  508                 *vpp = DETOV(tdp);
  509                 cnp->cn_flags |= SAVENAME;
  510                 if (!lockparent) {
  511                         VOP_UNLOCK(vdp, 0, td);
  512                         cnp->cn_flags |= PDIRUNLOCK;
  513                 }
  514                 return (0);
  515         }
  516 
  517         /*
  518          * Step through the translation in the name.  We do not `vput' the
  519          * directory because we may need it again if a symbolic link
  520          * is relative to the current directory.  Instead we save it
  521          * unlocked as "pdp".  We must get the target inode before unlocking
  522          * the directory to insure that the inode will not be removed
  523          * before we get it.  We prevent deadlock by always fetching
  524          * inodes from the root, moving down the directory tree. Thus
  525          * when following backward pointers ".." we must unlock the
  526          * parent directory before getting the requested directory.
  527          * There is a potential race condition here if both the current
  528          * and parent directories are removed before the VFS_VGET for the
  529          * inode associated with ".." returns.  We hope that this occurs
  530          * infrequently since we cannot avoid this race condition without
  531          * implementing a sophisticated deadlock detection algorithm.
  532          * Note also that this simple deadlock detection scheme will not
  533          * work if the filesystem has any hard links other than ".."
  534          * that point backwards in the directory structure.
  535          */
  536         pdp = vdp;
  537         if (flags & ISDOTDOT) {
  538                 VOP_UNLOCK(pdp, 0, td);
  539                 cnp->cn_flags |= PDIRUNLOCK;
  540                 error = deget(pmp, cluster, blkoff,  &tdp);
  541                 if (error) {
  542                         vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, td); 
  543                         cnp->cn_flags &= ~PDIRUNLOCK;
  544                         return (error);
  545                 }
  546                 if (lockparent && (flags & ISLASTCN)) {
  547                         error = vn_lock(pdp, LK_EXCLUSIVE, td);
  548                         if (error) {
  549                                 vput(DETOV(tdp));
  550                                 return (error);
  551                         }
  552                         cnp->cn_flags &= ~PDIRUNLOCK;
  553                 }
  554                 *vpp = DETOV(tdp);
  555         } else if (dp->de_StartCluster == scn && isadir) {
  556                 VREF(vdp);      /* we want ourself, ie "." */
  557                 *vpp = vdp;
  558         } else {
  559                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  560                         return (error);
  561                 if (!lockparent || !(flags & ISLASTCN)) {
  562                         VOP_UNLOCK(pdp, 0, td);
  563                         cnp->cn_flags |= PDIRUNLOCK;
  564                 }
  565                 *vpp = DETOV(tdp);
  566         }
  567 
  568         /*
  569          * Insert name into cache if appropriate.
  570          */
  571         if (cnp->cn_flags & MAKEENTRY)
  572                 cache_enter(vdp, *vpp, cnp);
  573         return (0);
  574 }
  575 
  576 /*
  577  * dep  - directory entry to copy into the directory
  578  * ddep - directory to add to
  579  * depp - return the address of the denode for the created directory entry
  580  *        if depp != 0
  581  * cnp  - componentname needed for Win95 long filenames
  582  */
  583 int
  584 createde(dep, ddep, depp, cnp)
  585         struct denode *dep;
  586         struct denode *ddep;
  587         struct denode **depp;
  588         struct componentname *cnp;
  589 {
  590         int error;
  591         u_long dirclust, diroffset;
  592         struct direntry *ndep;
  593         struct msdosfsmount *pmp = ddep->de_pmp;
  594         struct buf *bp;
  595         daddr_t bn;
  596         int blsize;
  597 
  598 #ifdef MSDOSFS_DEBUG
  599         printf("createde(dep %p, ddep %p, depp %p, cnp %p)\n",
  600             dep, ddep, depp, cnp);
  601 #endif
  602 
  603         /*
  604          * If no space left in the directory then allocate another cluster
  605          * and chain it onto the end of the file.  There is one exception
  606          * to this.  That is, if the root directory has no more space it
  607          * can NOT be expanded.  extendfile() checks for and fails attempts
  608          * to extend the root directory.  We just return an error in that
  609          * case.
  610          */
  611         if (ddep->de_fndoffset >= ddep->de_FileSize) {
  612                 diroffset = ddep->de_fndoffset + sizeof(struct direntry)
  613                     - ddep->de_FileSize;
  614                 dirclust = de_clcount(pmp, diroffset);
  615                 error = extendfile(ddep, dirclust, 0, 0, DE_CLEAR);
  616                 if (error) {
  617                         (void)detrunc(ddep, ddep->de_FileSize, 0, NOCRED, NULL);
  618                         return error;
  619                 }
  620 
  621                 /*
  622                  * Update the size of the directory
  623                  */
  624                 ddep->de_FileSize += de_cn2off(pmp, dirclust);
  625         }
  626 
  627         /*
  628          * We just read in the cluster with space.  Copy the new directory
  629          * entry in.  Then write it to disk. NOTE:  DOS directories
  630          * do not get smaller as clusters are emptied.
  631          */
  632         error = pcbmap(ddep, de_cluster(pmp, ddep->de_fndoffset),
  633                        &bn, &dirclust, &blsize);
  634         if (error)
  635                 return error;
  636         diroffset = ddep->de_fndoffset;
  637         if (dirclust != MSDOSFSROOT)
  638                 diroffset &= pmp->pm_crbomask;
  639         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) != 0) {
  640                 brelse(bp);
  641                 return error;
  642         }
  643         ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  644 
  645         DE_EXTERNALIZE(ndep, dep);
  646 
  647         /*
  648          * Now write the Win95 long name
  649          */
  650         if (ddep->de_fndcnt > 0) {
  651                 u_int8_t chksum = winChksum(ndep->deName);
  652                 const u_char *un = (const u_char *)cnp->cn_nameptr;
  653                 int unlen = cnp->cn_namelen;
  654                 int cnt = 1;
  655 
  656                 while (--ddep->de_fndcnt >= 0) {
  657                         if (!(ddep->de_fndoffset & pmp->pm_crbomask)) {
  658                                 if ((error = bwrite(bp)) != 0)
  659                                         return error;
  660 
  661                                 ddep->de_fndoffset -= sizeof(struct direntry);
  662                                 error = pcbmap(ddep,
  663                                                de_cluster(pmp,
  664                                                           ddep->de_fndoffset),
  665                                                &bn, 0, &blsize);
  666                                 if (error)
  667                                         return error;
  668 
  669                                 error = bread(pmp->pm_devvp, bn, blsize,
  670                                               NOCRED, &bp);
  671                                 if (error) {
  672                                         brelse(bp);
  673                                         return error;
  674                                 }
  675                                 ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  676                         } else {
  677                                 ndep--;
  678                                 ddep->de_fndoffset -= sizeof(struct direntry);
  679                         }
  680                         if (!unix2winfn(un, unlen, (struct winentry *)ndep,
  681                                         cnt++, chksum, pmp))
  682                                 break;
  683                 }
  684         }
  685 
  686         if ((error = bwrite(bp)) != 0)
  687                 return error;
  688 
  689         /*
  690          * If they want us to return with the denode gotten.
  691          */
  692         if (depp) {
  693                 if (dep->de_Attributes & ATTR_DIRECTORY) {
  694                         dirclust = dep->de_StartCluster;
  695                         if (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)
  696                                 dirclust = MSDOSFSROOT;
  697                         if (dirclust == MSDOSFSROOT)
  698                                 diroffset = MSDOSFSROOT_OFS;
  699                         else
  700                                 diroffset = 0;
  701                 }
  702                 return deget(pmp, dirclust, diroffset, depp);
  703         }
  704 
  705         return 0;
  706 }
  707 
  708 /*
  709  * Be sure a directory is empty except for "." and "..". Return 1 if empty,
  710  * return 0 if not empty or error.
  711  */
  712 int
  713 dosdirempty(dep)
  714         struct denode *dep;
  715 {
  716         int blsize;
  717         int error;
  718         u_long cn;
  719         daddr_t bn;
  720         struct buf *bp;
  721         struct msdosfsmount *pmp = dep->de_pmp;
  722         struct direntry *dentp;
  723 
  724         /*
  725          * Since the filesize field in directory entries for a directory is
  726          * zero, we just have to feel our way through the directory until
  727          * we hit end of file.
  728          */
  729         for (cn = 0;; cn++) {
  730                 if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
  731                         if (error == E2BIG)
  732                                 return (1);     /* it's empty */
  733                         return (0);
  734                 }
  735                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  736                 if (error) {
  737                         brelse(bp);
  738                         return (0);
  739                 }
  740                 for (dentp = (struct direntry *)bp->b_data;
  741                      (char *)dentp < bp->b_data + blsize;
  742                      dentp++) {
  743                         if (dentp->deName[0] != SLOT_DELETED &&
  744                             (dentp->deAttributes & ATTR_VOLUME) == 0) {
  745                                 /*
  746                                  * In dos directories an entry whose name
  747                                  * starts with SLOT_EMPTY (0) starts the
  748                                  * beginning of the unused part of the
  749                                  * directory, so we can just return that it
  750                                  * is empty.
  751                                  */
  752                                 if (dentp->deName[0] == SLOT_EMPTY) {
  753                                         brelse(bp);
  754                                         return (1);
  755                                 }
  756                                 /*
  757                                  * Any names other than "." and ".." in a
  758                                  * directory mean it is not empty.
  759                                  */
  760                                 if (bcmp(dentp->deName, ".          ", 11) &&
  761                                     bcmp(dentp->deName, "..         ", 11)) {
  762                                         brelse(bp);
  763 #ifdef MSDOSFS_DEBUG
  764                                         printf("dosdirempty(): entry found %02x, %02x\n",
  765                                             dentp->deName[0], dentp->deName[1]);
  766 #endif
  767                                         return (0);     /* not empty */
  768                                 }
  769                         }
  770                 }
  771                 brelse(bp);
  772         }
  773         /* NOTREACHED */
  774 }
  775 
  776 /*
  777  * Check to see if the directory described by target is in some
  778  * subdirectory of source.  This prevents something like the following from
  779  * succeeding and leaving a bunch or files and directories orphaned. mv
  780  * /a/b/c /a/b/c/d/e/f Where c and f are directories.
  781  *
  782  * source - the inode for /a/b/c
  783  * target - the inode for /a/b/c/d/e/f
  784  *
  785  * Returns 0 if target is NOT a subdirectory of source.
  786  * Otherwise returns a non-zero error number.
  787  * The target inode is always unlocked on return.
  788  */
  789 int
  790 doscheckpath(source, target)
  791         struct denode *source;
  792         struct denode *target;
  793 {
  794         daddr_t scn;
  795         struct msdosfsmount *pmp;
  796         struct direntry *ep;
  797         struct denode *dep;
  798         struct buf *bp = NULL;
  799         int error = 0;
  800 
  801         dep = target;
  802         if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
  803             (source->de_Attributes & ATTR_DIRECTORY) == 0) {
  804                 error = ENOTDIR;
  805                 goto out;
  806         }
  807         if (dep->de_StartCluster == source->de_StartCluster) {
  808                 error = EEXIST;
  809                 goto out;
  810         }
  811         if (dep->de_StartCluster == MSDOSFSROOT)
  812                 goto out;
  813         pmp = dep->de_pmp;
  814 #ifdef  DIAGNOSTIC
  815         if (pmp != source->de_pmp)
  816                 panic("doscheckpath: source and target on different filesystems");
  817 #endif
  818         if (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)
  819                 goto out;
  820 
  821         for (;;) {
  822                 if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
  823                         error = ENOTDIR;
  824                         break;
  825                 }
  826                 scn = dep->de_StartCluster;
  827                 error = bread(pmp->pm_devvp, cntobn(pmp, scn),
  828                               pmp->pm_bpcluster, NOCRED, &bp);
  829                 if (error)
  830                         break;
  831 
  832                 ep = (struct direntry *) bp->b_data + 1;
  833                 if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
  834                     bcmp(ep->deName, "..         ", 11) != 0) {
  835                         error = ENOTDIR;
  836                         break;
  837                 }
  838                 scn = getushort(ep->deStartCluster);
  839                 if (FAT32(pmp))
  840                         scn |= getushort(ep->deHighClust) << 16;
  841 
  842                 if (scn == source->de_StartCluster) {
  843                         error = EINVAL;
  844                         break;
  845                 }
  846                 if (scn == MSDOSFSROOT)
  847                         break;
  848                 if (FAT32(pmp) && scn == pmp->pm_rootdirblk) {
  849                         /*
  850                          * scn should be 0 in this case,
  851                          * but we silently ignore the error.
  852                          */
  853                         break;
  854                 }
  855 
  856                 vput(DETOV(dep));
  857                 brelse(bp);
  858                 bp = NULL;
  859                 /* NOTE: deget() clears dep on error */
  860                 if ((error = deget(pmp, scn, 0, &dep)) != 0)
  861                         break;
  862         }
  863 out:;
  864         if (bp)
  865                 brelse(bp);
  866         if (error == ENOTDIR)
  867                 printf("doscheckpath(): .. not a directory?\n");
  868         if (dep != NULL)
  869                 vput(DETOV(dep));
  870         return (error);
  871 }
  872 
  873 /*
  874  * Read in the disk block containing the directory entry (dirclu, dirofs)
  875  * and return the address of the buf header, and the address of the
  876  * directory entry within the block.
  877  */
  878 int
  879 readep(pmp, dirclust, diroffset, bpp, epp)
  880         struct msdosfsmount *pmp;
  881         u_long dirclust, diroffset;
  882         struct buf **bpp;
  883         struct direntry **epp;
  884 {
  885         int error;
  886         daddr_t bn;
  887         int blsize;
  888 
  889         blsize = pmp->pm_bpcluster;
  890         if (dirclust == MSDOSFSROOT
  891             && de_blk(pmp, diroffset + blsize) > pmp->pm_rootdirsize)
  892                 blsize = de_bn2off(pmp, pmp->pm_rootdirsize) & pmp->pm_crbomask;
  893         bn = detobn(pmp, dirclust, diroffset);
  894         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, bpp)) != 0) {
  895                 brelse(*bpp);
  896                 *bpp = NULL;
  897                 return (error);
  898         }
  899         if (epp)
  900                 *epp = bptoep(pmp, *bpp, diroffset);
  901         return (0);
  902 }
  903 
  904 /*
  905  * Read in the disk block containing the directory entry dep came from and
  906  * return the address of the buf header, and the address of the directory
  907  * entry within the block.
  908  */
  909 int
  910 readde(dep, bpp, epp)
  911         struct denode *dep;
  912         struct buf **bpp;
  913         struct direntry **epp;
  914 {
  915 
  916         return (readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
  917             bpp, epp));
  918 }
  919 
  920 /*
  921  * Remove a directory entry. At this point the file represented by the
  922  * directory entry to be removed is still full length until noone has it
  923  * open.  When the file no longer being used msdosfs_inactive() is called
  924  * and will truncate the file to 0 length.  When the vnode containing the
  925  * denode is needed for some other purpose by VFS it will call
  926  * msdosfs_reclaim() which will remove the denode from the denode cache.
  927  */
  928 int
  929 removede(pdep, dep)
  930         struct denode *pdep;    /* directory where the entry is removed */
  931         struct denode *dep;     /* file to be removed */
  932 {
  933         int error;
  934         struct direntry *ep;
  935         struct buf *bp;
  936         daddr_t bn;
  937         int blsize;
  938         struct msdosfsmount *pmp = pdep->de_pmp;
  939         u_long offset = pdep->de_fndoffset;
  940 
  941 #ifdef MSDOSFS_DEBUG
  942         printf("removede(): filename %s, dep %p, offset %08lx\n",
  943             dep->de_Name, dep, offset);
  944 #endif
  945 
  946         dep->de_refcnt--;
  947         offset += sizeof(struct direntry);
  948         do {
  949                 offset -= sizeof(struct direntry);
  950                 error = pcbmap(pdep, de_cluster(pmp, offset), &bn, 0, &blsize);
  951                 if (error)
  952                         return error;
  953                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  954                 if (error) {
  955                         brelse(bp);
  956                         return error;
  957                 }
  958                 ep = bptoep(pmp, bp, offset);
  959                 /*
  960                  * Check whether, if we came here the second time, i.e.
  961                  * when underflowing into the previous block, the last
  962                  * entry in this block is a longfilename entry, too.
  963                  */
  964                 if (ep->deAttributes != ATTR_WIN95
  965                     && offset != pdep->de_fndoffset) {
  966                         brelse(bp);
  967                         break;
  968                 }
  969                 offset += sizeof(struct direntry);
  970                 while (1) {
  971                         /*
  972                          * We are a bit agressive here in that we delete any Win95
  973                          * entries preceding this entry, not just the ones we "own".
  974                          * Since these presumably aren't valid anyway,
  975                          * there should be no harm.
  976                          */
  977                         offset -= sizeof(struct direntry);
  978                         ep--->deName[0] = SLOT_DELETED;
  979                         if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95)
  980                             || !(offset & pmp->pm_crbomask)
  981                             || ep->deAttributes != ATTR_WIN95)
  982                                 break;
  983                 }
  984                 if ((error = bwrite(bp)) != 0)
  985                         return error;
  986         } while (!(pmp->pm_flags & MSDOSFSMNT_NOWIN95)
  987             && !(offset & pmp->pm_crbomask)
  988             && offset);
  989         return 0;
  990 }
  991 
  992 /*
  993  * Create a unique DOS name in dvp
  994  */
  995 int
  996 uniqdosname(dep, cnp, cp)
  997         struct denode *dep;
  998         struct componentname *cnp;
  999         u_char *cp;
 1000 {
 1001         struct msdosfsmount *pmp = dep->de_pmp;
 1002         struct direntry *dentp;
 1003         int gen;
 1004         int blsize;
 1005         u_long cn;
 1006         daddr_t bn;
 1007         struct buf *bp;
 1008         int error;
 1009         
 1010         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
 1011                 return (unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
 1012                     cnp->cn_namelen, 0, pmp) ? 0 : EINVAL);
 1013 
 1014         for (gen = 1;; gen++) {
 1015                 /*
 1016                  * Generate DOS name with generation number
 1017                  */
 1018                 if (!unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
 1019                     cnp->cn_namelen, gen, pmp))
 1020                         return gen == 1 ? EINVAL : EEXIST;
 1021 
 1022                 /*
 1023                  * Now look for a dir entry with this exact name
 1024                  */
 1025                 for (cn = error = 0; !error; cn++) {
 1026                         if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
 1027                                 if (error == E2BIG)     /* EOF reached and not found */
 1028                                         return 0;
 1029                                 return error;
 1030                         }
 1031                         error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
 1032                         if (error) {
 1033                                 brelse(bp);
 1034                                 return error;
 1035                         }
 1036                         for (dentp = (struct direntry *)bp->b_data;
 1037                              (char *)dentp < bp->b_data + blsize;
 1038                              dentp++) {
 1039                                 if (dentp->deName[0] == SLOT_EMPTY) {
 1040                                         /*
 1041                                          * Last used entry and not found
 1042                                          */
 1043                                         brelse(bp);
 1044                                         return 0;
 1045                                 }
 1046                                 /*
 1047                                  * Ignore volume labels and Win95 entries
 1048                                  */
 1049                                 if (dentp->deAttributes & ATTR_VOLUME)
 1050                                         continue;
 1051                                 if (!bcmp(dentp->deName, cp, 11)) {
 1052                                         error = EEXIST;
 1053                                         break;
 1054                                 }
 1055                         }
 1056                         brelse(bp);
 1057                 }
 1058         }
 1059 }
 1060 
 1061 /*
 1062  * Find any Win'95 long filename entry in directory dep
 1063  */
 1064 int
 1065 findwin95(dep)
 1066         struct denode *dep;
 1067 {
 1068         struct msdosfsmount *pmp = dep->de_pmp;
 1069         struct direntry *dentp;
 1070         int blsize, win95;
 1071         u_long cn;
 1072         daddr_t bn;
 1073         struct buf *bp;
 1074 
 1075         win95 = 1;
 1076         /*
 1077          * Read through the directory looking for Win'95 entries
 1078          * Note: Error currently handled just as EOF                    XXX
 1079          */
 1080         for (cn = 0;; cn++) {
 1081                 if (pcbmap(dep, cn, &bn, 0, &blsize))
 1082                         return (win95);
 1083                 if (bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) {
 1084                         brelse(bp);
 1085                         return (win95);
 1086                 }
 1087                 for (dentp = (struct direntry *)bp->b_data;
 1088                      (char *)dentp < bp->b_data + blsize;
 1089                      dentp++) {
 1090                         if (dentp->deName[0] == SLOT_EMPTY) {
 1091                                 /*
 1092                                  * Last used entry and not found
 1093                                  */
 1094                                 brelse(bp);
 1095                                 return (win95);
 1096                         }
 1097                         if (dentp->deName[0] == SLOT_DELETED) {
 1098                                 /*
 1099                                  * Ignore deleted files
 1100                                  * Note: might be an indication of Win'95 anyway        XXX
 1101                                  */
 1102                                 continue;
 1103                         }
 1104                         if (dentp->deAttributes == ATTR_WIN95) {
 1105                                 brelse(bp);
 1106                                 return 1;
 1107                         }
 1108                         win95 = 0;
 1109                 }
 1110                 brelse(bp);
 1111         }
 1112 }

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