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

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    1 /* $FreeBSD: releng/9.0/sys/fs/msdosfs/msdosfs_lookup.c 220014 2011-03-25 22:31:28Z kib $ */
    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/buf.h>
   54 #include <sys/mount.h>
   55 #include <sys/namei.h>
   56 #include <sys/vnode.h>
   57 
   58 #include <fs/msdosfs/bpb.h>
   59 #include <fs/msdosfs/direntry.h>
   60 #include <fs/msdosfs/denode.h>
   61 #include <fs/msdosfs/fat.h>
   62 #include <fs/msdosfs/msdosfsmount.h>
   63 
   64 static int msdosfs_lookup_(struct vnode *vdp, struct vnode **vpp,
   65     struct componentname *cnp, u_int64_t *inum);
   66 static int msdosfs_deget_dotdot(struct vnode *vp, u_long cluster, int blkoff,
   67     struct vnode **rvp);
   68 
   69 int
   70 msdosfs_lookup(struct vop_cachedlookup_args *ap)
   71 {
   72 
   73         return (msdosfs_lookup_(ap->a_dvp, ap->a_vpp, ap->a_cnp, NULL));
   74 }
   75 
   76 /*
   77  * When we search a directory the blocks containing directory entries are
   78  * read and examined.  The directory entries contain information that would
   79  * normally be in the inode of a unix filesystem.  This means that some of
   80  * a directory's contents may also be in memory resident denodes (sort of
   81  * an inode).  This can cause problems if we are searching while some other
   82  * process is modifying a directory.  To prevent one process from accessing
   83  * incompletely modified directory information we depend upon being the
   84  * sole owner of a directory block.  bread/brelse provide this service.
   85  * This being the case, when a process modifies a directory it must first
   86  * acquire the disk block that contains the directory entry to be modified.
   87  * Then update the disk block and the denode, and then write the disk block
   88  * out to disk.  This way disk blocks containing directory entries and in
   89  * memory denode's will be in synch.
   90  */
   91 static int
   92 msdosfs_lookup_(struct vnode *vdp, struct vnode **vpp,
   93     struct componentname *cnp, u_int64_t *dd_inum)
   94 {
   95         struct mbnambuf nb;
   96         daddr_t bn;
   97         int error;
   98         int slotcount;
   99         int slotoffset = 0;
  100         int frcn;
  101         u_long cluster;
  102         int blkoff;
  103         int diroff;
  104         int blsize;
  105         int isadir;             /* ~0 if found direntry is a directory   */
  106         u_long scn;             /* starting cluster number               */
  107         struct vnode *pdp;
  108         struct denode *dp;
  109         struct denode *tdp;
  110         struct msdosfsmount *pmp;
  111         struct buf *bp = 0;
  112         struct direntry *dep = NULL;
  113         u_char dosfilename[12];
  114         int flags = cnp->cn_flags;
  115         int nameiop = cnp->cn_nameiop;
  116         int unlen;
  117         u_int64_t inode1;
  118 
  119         int wincnt = 1;
  120         int chksum = -1, chksum_ok;
  121         int olddos = 1;
  122 
  123 #ifdef MSDOSFS_DEBUG
  124         printf("msdosfs_lookup(): looking for %s\n", cnp->cn_nameptr);
  125 #endif
  126         dp = VTODE(vdp);
  127         pmp = dp->de_pmp;
  128 #ifdef MSDOSFS_DEBUG
  129         printf("msdosfs_lookup(): vdp %p, dp %p, Attr %02x\n",
  130             vdp, dp, dp->de_Attributes);
  131 #endif
  132 
  133  restart:
  134         if (vpp != NULL)
  135                 *vpp = NULL;
  136         /*
  137          * If they are going after the . or .. entry in the root directory,
  138          * they won't find it.  DOS filesystems don't have them in the root
  139          * directory.  So, we fake it. deget() is in on this scam too.
  140          */
  141         if ((vdp->v_vflag & VV_ROOT) && cnp->cn_nameptr[0] == '.' &&
  142             (cnp->cn_namelen == 1 ||
  143                 (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.'))) {
  144                 isadir = ATTR_DIRECTORY;
  145                 scn = MSDOSFSROOT;
  146 #ifdef MSDOSFS_DEBUG
  147                 printf("msdosfs_lookup(): looking for . or .. in root directory\n");
  148 #endif
  149                 cluster = MSDOSFSROOT;
  150                 blkoff = MSDOSFSROOT_OFS;
  151                 goto foundroot;
  152         }
  153 
  154         switch (unix2dosfn((const u_char *)cnp->cn_nameptr, dosfilename,
  155             cnp->cn_namelen, 0, pmp)) {
  156         case 0:
  157                 return (EINVAL);
  158         case 1:
  159                 break;
  160         case 2:
  161                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  162                     cnp->cn_namelen, pmp) + 1;
  163                 break;
  164         case 3:
  165                 olddos = 0;
  166                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  167                     cnp->cn_namelen, pmp) + 1;
  168                 break;
  169         }
  170         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME) {
  171                 wincnt = 1;
  172                 olddos = 1;
  173         }
  174         unlen = winLenFixup(cnp->cn_nameptr, cnp->cn_namelen);
  175 
  176         /*
  177          * Suppress search for slots unless creating
  178          * file and at end of pathname, in which case
  179          * we watch for a place to put the new file in
  180          * case it doesn't already exist.
  181          */
  182         slotcount = wincnt;
  183         if ((nameiop == CREATE || nameiop == RENAME) &&
  184             (flags & ISLASTCN))
  185                 slotcount = 0;
  186 
  187 #ifdef MSDOSFS_DEBUG
  188         printf("msdosfs_lookup(): dos version of filename %s, length %ld\n",
  189             dosfilename, cnp->cn_namelen);
  190 #endif
  191         /*
  192          * Search the directory pointed at by vdp for the name pointed at
  193          * by cnp->cn_nameptr.
  194          */
  195         tdp = NULL;
  196         mbnambuf_init(&nb);
  197         /*
  198          * The outer loop ranges over the clusters that make up the
  199          * directory.  Note that the root directory is different from all
  200          * other directories.  It has a fixed number of blocks that are not
  201          * part of the pool of allocatable clusters.  So, we treat it a
  202          * little differently. The root directory starts at "cluster" 0.
  203          */
  204         diroff = 0;
  205         for (frcn = 0;; frcn++) {
  206                 error = pcbmap(dp, frcn, &bn, &cluster, &blsize);
  207                 if (error) {
  208                         if (error == E2BIG)
  209                                 break;
  210                         return (error);
  211                 }
  212                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  213                 if (error) {
  214                         brelse(bp);
  215                         return (error);
  216                 }
  217                 for (blkoff = 0; blkoff < blsize;
  218                      blkoff += sizeof(struct direntry),
  219                      diroff += sizeof(struct direntry)) {
  220                         dep = (struct direntry *)(bp->b_data + blkoff);
  221                         /*
  222                          * If the slot is empty and we are still looking
  223                          * for an empty then remember this one.  If the
  224                          * slot is not empty then check to see if it
  225                          * matches what we are looking for.  If the slot
  226                          * has never been filled with anything, then the
  227                          * remainder of the directory has never been used,
  228                          * so there is no point in searching it.
  229                          */
  230                         if (dep->deName[0] == SLOT_EMPTY ||
  231                             dep->deName[0] == SLOT_DELETED) {
  232                                 /*
  233                                  * Drop memory of previous long matches
  234                                  */
  235                                 chksum = -1;
  236                                 mbnambuf_init(&nb);
  237 
  238                                 if (slotcount < wincnt) {
  239                                         slotcount++;
  240                                         slotoffset = diroff;
  241                                 }
  242                                 if (dep->deName[0] == SLOT_EMPTY) {
  243                                         brelse(bp);
  244                                         goto notfound;
  245                                 }
  246                         } else {
  247                                 /*
  248                                  * If there wasn't enough space for our winentries,
  249                                  * forget about the empty space
  250                                  */
  251                                 if (slotcount < wincnt)
  252                                         slotcount = 0;
  253 
  254                                 /*
  255                                  * Check for Win95 long filename entry
  256                                  */
  257                                 if (dep->deAttributes == ATTR_WIN95) {
  258                                         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
  259                                                 continue;
  260 
  261                                         chksum = win2unixfn(&nb,
  262                                             (struct winentry *)dep, chksum,
  263                                             pmp);
  264                                         continue;
  265                                 }
  266 
  267                                 chksum = winChkName(&nb,
  268                                     (const u_char *)cnp->cn_nameptr, unlen,
  269                                     chksum, pmp);
  270                                 if (chksum == -2) {
  271                                         chksum = -1;
  272                                         continue;
  273                                 }
  274 
  275                                 /*
  276                                  * Ignore volume labels (anywhere, not just
  277                                  * the root directory).
  278                                  */
  279                                 if (dep->deAttributes & ATTR_VOLUME) {
  280                                         chksum = -1;
  281                                         continue;
  282                                 }
  283 
  284                                 /*
  285                                  * Check for a checksum or name match
  286                                  */
  287                                 chksum_ok = (chksum == winChksum(dep->deName));
  288                                 if (!chksum_ok
  289                                     && (!olddos || bcmp(dosfilename, dep->deName, 11))) {
  290                                         chksum = -1;
  291                                         continue;
  292                                 }
  293 #ifdef MSDOSFS_DEBUG
  294                                 printf("msdosfs_lookup(): match blkoff %d, diroff %d\n",
  295                                     blkoff, diroff);
  296 #endif
  297                                 /*
  298                                  * Remember where this directory
  299                                  * entry came from for whoever did
  300                                  * this lookup.
  301                                  */
  302                                 dp->de_fndoffset = diroff;
  303                                 if (chksum_ok && nameiop == RENAME) {
  304                                         /*
  305                                          * Target had correct long name
  306                                          * directory entries, reuse them
  307                                          * as needed.
  308                                          */
  309                                         dp->de_fndcnt = wincnt - 1;
  310                                 } else {
  311                                         /*
  312                                          * Long name directory entries
  313                                          * not present or corrupt, can only
  314                                          * reuse dos directory entry.
  315                                          */
  316                                         dp->de_fndcnt = 0;
  317                                 }
  318 
  319                                 goto found;
  320                         }
  321                 }       /* for (blkoff = 0; .... */
  322                 /*
  323                  * Release the buffer holding the directory cluster just
  324                  * searched.
  325                  */
  326                 brelse(bp);
  327         }       /* for (frcn = 0; ; frcn++) */
  328 
  329 notfound:
  330         /*
  331          * We hold no disk buffers at this point.
  332          */
  333 
  334         /*
  335          * Fixup the slot description to point to the place where
  336          * we might put the new DOS direntry (putting the Win95
  337          * long name entries before that)
  338          */
  339         if (!slotcount) {
  340                 slotcount = 1;
  341                 slotoffset = diroff;
  342         }
  343         if (wincnt > slotcount)
  344                 slotoffset += sizeof(struct direntry) * (wincnt - slotcount);
  345 
  346         /*
  347          * If we get here we didn't find the entry we were looking for. But
  348          * that's ok if we are creating or renaming and are at the end of
  349          * the pathname and the directory hasn't been removed.
  350          */
  351 #ifdef MSDOSFS_DEBUG
  352         printf("msdosfs_lookup(): op %d, refcnt %ld\n",
  353             nameiop, dp->de_refcnt);
  354         printf("               slotcount %d, slotoffset %d\n",
  355                slotcount, slotoffset);
  356 #endif
  357         if ((nameiop == CREATE || nameiop == RENAME) &&
  358             (flags & ISLASTCN) && dp->de_refcnt != 0) {
  359                 /*
  360                  * Access for write is interpreted as allowing
  361                  * creation of files in the directory.
  362                  */
  363                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  364                 if (error)
  365                         return (error);
  366                 /*
  367                  * Return an indication of where the new directory
  368                  * entry should be put.
  369                  */
  370                 dp->de_fndoffset = slotoffset;
  371                 dp->de_fndcnt = wincnt - 1;
  372 
  373                 /*
  374                  * We return with the directory locked, so that
  375                  * the parameters we set up above will still be
  376                  * valid if we actually decide to do a direnter().
  377                  * We return ni_vp == NULL to indicate that the entry
  378                  * does not currently exist; we leave a pointer to
  379                  * the (locked) directory inode in ndp->ni_dvp.
  380                  * The pathname buffer is saved so that the name
  381                  * can be obtained later.
  382                  *
  383                  * NB - if the directory is unlocked, then this
  384                  * information cannot be used.
  385                  */
  386                 cnp->cn_flags |= SAVENAME;
  387                 return (EJUSTRETURN);
  388         }
  389 #if 0
  390         /*
  391          * Insert name into cache (as non-existent) if appropriate.
  392          *
  393          * XXX Negative caching is broken for msdosfs because the name
  394          * cache doesn't understand peculiarities such as case insensitivity
  395          * and 8.3 filenames.  Hence, it may not invalidate all negative
  396          * entries if a file with this name is later created.
  397          */
  398         if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
  399                 cache_enter(vdp, *vpp, cnp);
  400 #endif
  401         return (ENOENT);
  402 
  403 found:
  404         /*
  405          * NOTE:  We still have the buffer with matched directory entry at
  406          * this point.
  407          */
  408         isadir = dep->deAttributes & ATTR_DIRECTORY;
  409         scn = getushort(dep->deStartCluster);
  410         if (FAT32(pmp)) {
  411                 scn |= getushort(dep->deHighClust) << 16;
  412                 if (scn == pmp->pm_rootdirblk) {
  413                         /*
  414                          * There should actually be 0 here.
  415                          * Just ignore the error.
  416                          */
  417                         scn = MSDOSFSROOT;
  418                 }
  419         }
  420 
  421         if (isadir) {
  422                 cluster = scn;
  423                 if (cluster == MSDOSFSROOT)
  424                         blkoff = MSDOSFSROOT_OFS;
  425                 else
  426                         blkoff = 0;
  427         } else if (cluster == MSDOSFSROOT)
  428                 blkoff = diroff;
  429 
  430         /*
  431          * Now release buf to allow deget to read the entry again.
  432          * Reserving it here and giving it to deget could result
  433          * in a deadlock.
  434          */
  435         brelse(bp);
  436         bp = 0;
  437         
  438 foundroot:
  439         /*
  440          * If we entered at foundroot, then we are looking for the . or ..
  441          * entry of the filesystems root directory.  isadir and scn were
  442          * setup before jumping here.  And, bp is already null.
  443          */
  444         if (FAT32(pmp) && scn == MSDOSFSROOT)
  445                 scn = pmp->pm_rootdirblk;
  446 
  447         if (dd_inum != NULL) {
  448                 *dd_inum = (uint64_t)pmp->pm_bpcluster * scn + blkoff;
  449                 return (0);
  450         }
  451 
  452         /*
  453          * If deleting, and at end of pathname, return
  454          * parameters which can be used to remove file.
  455          */
  456         if (nameiop == DELETE && (flags & ISLASTCN)) {
  457                 /*
  458                  * Don't allow deleting the root.
  459                  */
  460                 if (blkoff == MSDOSFSROOT_OFS)
  461                         return (EBUSY);
  462 
  463                 /*
  464                  * Write access to directory required to delete files.
  465                  */
  466                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  467                 if (error)
  468                         return (error);
  469 
  470                 /*
  471                  * Return pointer to current entry in dp->i_offset.
  472                  * Save directory inode pointer in ndp->ni_dvp for dirremove().
  473                  */
  474                 if (dp->de_StartCluster == scn && isadir) {     /* "." */
  475                         VREF(vdp);
  476                         *vpp = vdp;
  477                         return (0);
  478                 }
  479                 error = deget(pmp, cluster, blkoff, &tdp);
  480                 if (error)
  481                         return (error);
  482                 *vpp = DETOV(tdp);
  483                 return (0);
  484         }
  485 
  486         /*
  487          * If rewriting (RENAME), return the inode and the
  488          * information required to rewrite the present directory
  489          * Must get inode of directory entry to verify it's a
  490          * regular file, or empty directory.
  491          */
  492         if (nameiop == RENAME && (flags & ISLASTCN)) {
  493                 if (blkoff == MSDOSFSROOT_OFS)
  494                         return (EBUSY);
  495 
  496                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  497                 if (error)
  498                         return (error);
  499 
  500                 /*
  501                  * Careful about locking second inode.
  502                  * This can only occur if the target is ".".
  503                  */
  504                 if (dp->de_StartCluster == scn && isadir)
  505                         return (EISDIR);
  506 
  507                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  508                         return (error);
  509                 *vpp = DETOV(tdp);
  510                 cnp->cn_flags |= SAVENAME;
  511                 return (0);
  512         }
  513 
  514         /*
  515          * Step through the translation in the name.  We do not `vput' the
  516          * directory because we may need it again if a symbolic link
  517          * is relative to the current directory.  Instead we save it
  518          * unlocked as "pdp".  We must get the target inode before unlocking
  519          * the directory to insure that the inode will not be removed
  520          * before we get it.  We prevent deadlock by always fetching
  521          * inodes from the root, moving down the directory tree. Thus
  522          * when following backward pointers ".." we must unlock the
  523          * parent directory before getting the requested directory.
  524          */
  525         pdp = vdp;
  526         if (flags & ISDOTDOT) {
  527                 error = msdosfs_deget_dotdot(pdp, cluster, blkoff, vpp);
  528                 if (error) {
  529                         *vpp = NULL;
  530                         return (error);
  531                 }
  532                 /*
  533                  * Recheck that ".." still points to the inode we
  534                  * looked up before pdp lock was dropped.
  535                  */
  536                 error = msdosfs_lookup_(pdp, NULL, cnp, &inode1);
  537                 if (error) {
  538                         vput(*vpp);
  539                         *vpp = NULL;
  540                         return (error);
  541                 }
  542                 if (VTODE(*vpp)->de_inode != inode1) {
  543                         vput(*vpp);
  544                         goto restart;
  545                 }
  546         } else if (dp->de_StartCluster == scn && isadir) {
  547                 VREF(vdp);      /* we want ourself, ie "." */
  548                 *vpp = vdp;
  549         } else {
  550                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  551                         return (error);
  552                 *vpp = DETOV(tdp);
  553         }
  554 
  555         /*
  556          * Insert name into cache if appropriate.
  557          */
  558         if (cnp->cn_flags & MAKEENTRY)
  559                 cache_enter(vdp, *vpp, cnp);
  560         return (0);
  561 }
  562 
  563 static int
  564 msdosfs_deget_dotdot(struct vnode *vp, u_long cluster, int blkoff,
  565     struct vnode **rvp)
  566 {
  567         struct mount *mp;
  568         struct msdosfsmount *pmp;
  569         struct denode *rdp;
  570         int ltype, error;
  571 
  572         mp = vp->v_mount;
  573         pmp = VFSTOMSDOSFS(mp);
  574         ltype = VOP_ISLOCKED(vp);
  575         KASSERT(ltype == LK_EXCLUSIVE || ltype == LK_SHARED,
  576             ("msdosfs_deget_dotdot: vp not locked"));
  577 
  578         error = vfs_busy(mp, MBF_NOWAIT);
  579         if (error != 0) {
  580                 vfs_ref(mp);
  581                 VOP_UNLOCK(vp, 0);
  582                 error = vfs_busy(mp, 0);
  583                 vn_lock(vp, ltype | LK_RETRY);
  584                 vfs_rel(mp);
  585                 if (error != 0)
  586                         return (ENOENT);
  587                 if (vp->v_iflag & VI_DOOMED) {
  588                         vfs_unbusy(mp);
  589                         return (ENOENT);
  590                 }
  591         }
  592         VOP_UNLOCK(vp, 0);
  593         error = deget(pmp, cluster, blkoff,  &rdp);
  594         vfs_unbusy(mp);
  595         if (error == 0)
  596                 *rvp = DETOV(rdp);
  597         if (*rvp != vp)
  598                 vn_lock(vp, ltype | LK_RETRY);
  599         if (vp->v_iflag & VI_DOOMED) {
  600                 if (error == 0) {
  601                         if (*rvp == vp)
  602                                 vunref(*rvp);
  603                         else
  604                                 vput(*rvp);
  605                 }
  606                 error = ENOENT;
  607         }
  608         return (error);
  609 }
  610 
  611 /*
  612  * dep  - directory entry to copy into the directory
  613  * ddep - directory to add to
  614  * depp - return the address of the denode for the created directory entry
  615  *        if depp != 0
  616  * cnp  - componentname needed for Win95 long filenames
  617  */
  618 int
  619 createde(dep, ddep, depp, cnp)
  620         struct denode *dep;
  621         struct denode *ddep;
  622         struct denode **depp;
  623         struct componentname *cnp;
  624 {
  625         int error;
  626         u_long dirclust, diroffset;
  627         struct direntry *ndep;
  628         struct msdosfsmount *pmp = ddep->de_pmp;
  629         struct buf *bp;
  630         daddr_t bn;
  631         int blsize;
  632 
  633 #ifdef MSDOSFS_DEBUG
  634         printf("createde(dep %p, ddep %p, depp %p, cnp %p)\n",
  635             dep, ddep, depp, cnp);
  636 #endif
  637 
  638         /*
  639          * If no space left in the directory then allocate another cluster
  640          * and chain it onto the end of the file.  There is one exception
  641          * to this.  That is, if the root directory has no more space it
  642          * can NOT be expanded.  extendfile() checks for and fails attempts
  643          * to extend the root directory.  We just return an error in that
  644          * case.
  645          */
  646         if (ddep->de_fndoffset >= ddep->de_FileSize) {
  647                 diroffset = ddep->de_fndoffset + sizeof(struct direntry)
  648                     - ddep->de_FileSize;
  649                 dirclust = de_clcount(pmp, diroffset);
  650                 error = extendfile(ddep, dirclust, 0, 0, DE_CLEAR);
  651                 if (error) {
  652                         (void)detrunc(ddep, ddep->de_FileSize, 0, NOCRED, NULL);
  653                         return error;
  654                 }
  655 
  656                 /*
  657                  * Update the size of the directory
  658                  */
  659                 ddep->de_FileSize += de_cn2off(pmp, dirclust);
  660         }
  661 
  662         /*
  663          * We just read in the cluster with space.  Copy the new directory
  664          * entry in.  Then write it to disk. NOTE:  DOS directories
  665          * do not get smaller as clusters are emptied.
  666          */
  667         error = pcbmap(ddep, de_cluster(pmp, ddep->de_fndoffset),
  668                        &bn, &dirclust, &blsize);
  669         if (error)
  670                 return error;
  671         diroffset = ddep->de_fndoffset;
  672         if (dirclust != MSDOSFSROOT)
  673                 diroffset &= pmp->pm_crbomask;
  674         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) != 0) {
  675                 brelse(bp);
  676                 return error;
  677         }
  678         ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  679 
  680         DE_EXTERNALIZE(ndep, dep);
  681 
  682         /*
  683          * Now write the Win95 long name
  684          */
  685         if (ddep->de_fndcnt > 0) {
  686                 u_int8_t chksum = winChksum(ndep->deName);
  687                 const u_char *un = (const u_char *)cnp->cn_nameptr;
  688                 int unlen = cnp->cn_namelen;
  689                 int cnt = 1;
  690 
  691                 while (--ddep->de_fndcnt >= 0) {
  692                         if (!(ddep->de_fndoffset & pmp->pm_crbomask)) {
  693                                 if (DETOV(ddep)->v_mount->mnt_flag & MNT_ASYNC)
  694                                         bdwrite(bp);
  695                                 else if ((error = bwrite(bp)) != 0)
  696                                         return error;
  697 
  698                                 ddep->de_fndoffset -= sizeof(struct direntry);
  699                                 error = pcbmap(ddep,
  700                                                de_cluster(pmp,
  701                                                           ddep->de_fndoffset),
  702                                                &bn, 0, &blsize);
  703                                 if (error)
  704                                         return error;
  705 
  706                                 error = bread(pmp->pm_devvp, bn, blsize,
  707                                               NOCRED, &bp);
  708                                 if (error) {
  709                                         brelse(bp);
  710                                         return error;
  711                                 }
  712                                 ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  713                         } else {
  714                                 ndep--;
  715                                 ddep->de_fndoffset -= sizeof(struct direntry);
  716                         }
  717                         if (!unix2winfn(un, unlen, (struct winentry *)ndep,
  718                                         cnt++, chksum, pmp))
  719                                 break;
  720                 }
  721         }
  722 
  723         if (DETOV(ddep)->v_mount->mnt_flag & MNT_ASYNC)
  724                 bdwrite(bp);
  725         else if ((error = bwrite(bp)) != 0)
  726                 return error;
  727 
  728         /*
  729          * If they want us to return with the denode gotten.
  730          */
  731         if (depp) {
  732                 if (dep->de_Attributes & ATTR_DIRECTORY) {
  733                         dirclust = dep->de_StartCluster;
  734                         if (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)
  735                                 dirclust = MSDOSFSROOT;
  736                         if (dirclust == MSDOSFSROOT)
  737                                 diroffset = MSDOSFSROOT_OFS;
  738                         else
  739                                 diroffset = 0;
  740                 }
  741                 return deget(pmp, dirclust, diroffset, depp);
  742         }
  743 
  744         return 0;
  745 }
  746 
  747 /*
  748  * Be sure a directory is empty except for "." and "..". Return 1 if empty,
  749  * return 0 if not empty or error.
  750  */
  751 int
  752 dosdirempty(dep)
  753         struct denode *dep;
  754 {
  755         int blsize;
  756         int error;
  757         u_long cn;
  758         daddr_t bn;
  759         struct buf *bp;
  760         struct msdosfsmount *pmp = dep->de_pmp;
  761         struct direntry *dentp;
  762 
  763         /*
  764          * Since the filesize field in directory entries for a directory is
  765          * zero, we just have to feel our way through the directory until
  766          * we hit end of file.
  767          */
  768         for (cn = 0;; cn++) {
  769                 if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
  770                         if (error == E2BIG)
  771                                 return (1);     /* it's empty */
  772                         return (0);
  773                 }
  774                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  775                 if (error) {
  776                         brelse(bp);
  777                         return (0);
  778                 }
  779                 for (dentp = (struct direntry *)bp->b_data;
  780                      (char *)dentp < bp->b_data + blsize;
  781                      dentp++) {
  782                         if (dentp->deName[0] != SLOT_DELETED &&
  783                             (dentp->deAttributes & ATTR_VOLUME) == 0) {
  784                                 /*
  785                                  * In dos directories an entry whose name
  786                                  * starts with SLOT_EMPTY (0) starts the
  787                                  * beginning of the unused part of the
  788                                  * directory, so we can just return that it
  789                                  * is empty.
  790                                  */
  791                                 if (dentp->deName[0] == SLOT_EMPTY) {
  792                                         brelse(bp);
  793                                         return (1);
  794                                 }
  795                                 /*
  796                                  * Any names other than "." and ".." in a
  797                                  * directory mean it is not empty.
  798                                  */
  799                                 if (bcmp(dentp->deName, ".          ", 11) &&
  800                                     bcmp(dentp->deName, "..         ", 11)) {
  801                                         brelse(bp);
  802 #ifdef MSDOSFS_DEBUG
  803                                         printf("dosdirempty(): entry found %02x, %02x\n",
  804                                             dentp->deName[0], dentp->deName[1]);
  805 #endif
  806                                         return (0);     /* not empty */
  807                                 }
  808                         }
  809                 }
  810                 brelse(bp);
  811         }
  812         /* NOTREACHED */
  813 }
  814 
  815 /*
  816  * Check to see if the directory described by target is in some
  817  * subdirectory of source.  This prevents something like the following from
  818  * succeeding and leaving a bunch or files and directories orphaned. mv
  819  * /a/b/c /a/b/c/d/e/f Where c and f are directories.
  820  *
  821  * source - the inode for /a/b/c
  822  * target - the inode for /a/b/c/d/e/f
  823  *
  824  * Returns 0 if target is NOT a subdirectory of source.
  825  * Otherwise returns a non-zero error number.
  826  * The target inode is always unlocked on return.
  827  */
  828 int
  829 doscheckpath(source, target)
  830         struct denode *source;
  831         struct denode *target;
  832 {
  833         daddr_t scn;
  834         struct msdosfsmount *pmp;
  835         struct direntry *ep;
  836         struct denode *dep;
  837         struct buf *bp = NULL;
  838         int error = 0;
  839 
  840         dep = target;
  841         if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
  842             (source->de_Attributes & ATTR_DIRECTORY) == 0) {
  843                 error = ENOTDIR;
  844                 goto out;
  845         }
  846         if (dep->de_StartCluster == source->de_StartCluster) {
  847                 error = EEXIST;
  848                 goto out;
  849         }
  850         if (dep->de_StartCluster == MSDOSFSROOT)
  851                 goto out;
  852         pmp = dep->de_pmp;
  853 #ifdef  DIAGNOSTIC
  854         if (pmp != source->de_pmp)
  855                 panic("doscheckpath: source and target on different filesystems");
  856 #endif
  857         if (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)
  858                 goto out;
  859 
  860         for (;;) {
  861                 if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
  862                         error = ENOTDIR;
  863                         break;
  864                 }
  865                 scn = dep->de_StartCluster;
  866                 error = bread(pmp->pm_devvp, cntobn(pmp, scn),
  867                               pmp->pm_bpcluster, NOCRED, &bp);
  868                 if (error)
  869                         break;
  870 
  871                 ep = (struct direntry *) bp->b_data + 1;
  872                 if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
  873                     bcmp(ep->deName, "..         ", 11) != 0) {
  874                         error = ENOTDIR;
  875                         break;
  876                 }
  877                 scn = getushort(ep->deStartCluster);
  878                 if (FAT32(pmp))
  879                         scn |= getushort(ep->deHighClust) << 16;
  880 
  881                 if (scn == source->de_StartCluster) {
  882                         error = EINVAL;
  883                         break;
  884                 }
  885                 if (scn == MSDOSFSROOT)
  886                         break;
  887                 if (FAT32(pmp) && scn == pmp->pm_rootdirblk) {
  888                         /*
  889                          * scn should be 0 in this case,
  890                          * but we silently ignore the error.
  891                          */
  892                         break;
  893                 }
  894 
  895                 vput(DETOV(dep));
  896                 brelse(bp);
  897                 bp = NULL;
  898                 /* NOTE: deget() clears dep on error */
  899                 if ((error = deget(pmp, scn, 0, &dep)) != 0)
  900                         break;
  901         }
  902 out:;
  903         if (bp)
  904                 brelse(bp);
  905         if (error == ENOTDIR)
  906                 printf("doscheckpath(): .. not a directory?\n");
  907         if (dep != NULL)
  908                 vput(DETOV(dep));
  909         return (error);
  910 }
  911 
  912 /*
  913  * Read in the disk block containing the directory entry (dirclu, dirofs)
  914  * and return the address of the buf header, and the address of the
  915  * directory entry within the block.
  916  */
  917 int
  918 readep(pmp, dirclust, diroffset, bpp, epp)
  919         struct msdosfsmount *pmp;
  920         u_long dirclust, diroffset;
  921         struct buf **bpp;
  922         struct direntry **epp;
  923 {
  924         int error;
  925         daddr_t bn;
  926         int blsize;
  927 
  928         blsize = pmp->pm_bpcluster;
  929         if (dirclust == MSDOSFSROOT
  930             && de_blk(pmp, diroffset + blsize) > pmp->pm_rootdirsize)
  931                 blsize = de_bn2off(pmp, pmp->pm_rootdirsize) & pmp->pm_crbomask;
  932         bn = detobn(pmp, dirclust, diroffset);
  933         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, bpp)) != 0) {
  934                 brelse(*bpp);
  935                 *bpp = NULL;
  936                 return (error);
  937         }
  938         if (epp)
  939                 *epp = bptoep(pmp, *bpp, diroffset);
  940         return (0);
  941 }
  942 
  943 /*
  944  * Read in the disk block containing the directory entry dep came from and
  945  * return the address of the buf header, and the address of the directory
  946  * entry within the block.
  947  */
  948 int
  949 readde(dep, bpp, epp)
  950         struct denode *dep;
  951         struct buf **bpp;
  952         struct direntry **epp;
  953 {
  954 
  955         return (readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
  956             bpp, epp));
  957 }
  958 
  959 /*
  960  * Remove a directory entry. At this point the file represented by the
  961  * directory entry to be removed is still full length until noone has it
  962  * open.  When the file no longer being used msdosfs_inactive() is called
  963  * and will truncate the file to 0 length.  When the vnode containing the
  964  * denode is needed for some other purpose by VFS it will call
  965  * msdosfs_reclaim() which will remove the denode from the denode cache.
  966  */
  967 int
  968 removede(pdep, dep)
  969         struct denode *pdep;    /* directory where the entry is removed */
  970         struct denode *dep;     /* file to be removed */
  971 {
  972         int error;
  973         struct direntry *ep;
  974         struct buf *bp;
  975         daddr_t bn;
  976         int blsize;
  977         struct msdosfsmount *pmp = pdep->de_pmp;
  978         u_long offset = pdep->de_fndoffset;
  979 
  980 #ifdef MSDOSFS_DEBUG
  981         printf("removede(): filename %s, dep %p, offset %08lx\n",
  982             dep->de_Name, dep, offset);
  983 #endif
  984 
  985         dep->de_refcnt--;
  986         offset += sizeof(struct direntry);
  987         do {
  988                 offset -= sizeof(struct direntry);
  989                 error = pcbmap(pdep, de_cluster(pmp, offset), &bn, 0, &blsize);
  990                 if (error)
  991                         return error;
  992                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  993                 if (error) {
  994                         brelse(bp);
  995                         return error;
  996                 }
  997                 ep = bptoep(pmp, bp, offset);
  998                 /*
  999                  * Check whether, if we came here the second time, i.e.
 1000                  * when underflowing into the previous block, the last
 1001                  * entry in this block is a longfilename entry, too.
 1002                  */
 1003                 if (ep->deAttributes != ATTR_WIN95
 1004                     && offset != pdep->de_fndoffset) {
 1005                         brelse(bp);
 1006                         break;
 1007                 }
 1008                 offset += sizeof(struct direntry);
 1009                 while (1) {
 1010                         /*
 1011                          * We are a bit agressive here in that we delete any Win95
 1012                          * entries preceding this entry, not just the ones we "own".
 1013                          * Since these presumably aren't valid anyway,
 1014                          * there should be no harm.
 1015                          */
 1016                         offset -= sizeof(struct direntry);
 1017                         ep--->deName[0] = SLOT_DELETED;
 1018                         if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95)
 1019                             || !(offset & pmp->pm_crbomask)
 1020                             || ep->deAttributes != ATTR_WIN95)
 1021                                 break;
 1022                 }
 1023                 if (DETOV(pdep)->v_mount->mnt_flag & MNT_ASYNC)
 1024                         bdwrite(bp);
 1025                 else if ((error = bwrite(bp)) != 0)
 1026                         return error;
 1027         } while (!(pmp->pm_flags & MSDOSFSMNT_NOWIN95)
 1028             && !(offset & pmp->pm_crbomask)
 1029             && offset);
 1030         return 0;
 1031 }
 1032 
 1033 /*
 1034  * Create a unique DOS name in dvp
 1035  */
 1036 int
 1037 uniqdosname(dep, cnp, cp)
 1038         struct denode *dep;
 1039         struct componentname *cnp;
 1040         u_char *cp;
 1041 {
 1042         struct msdosfsmount *pmp = dep->de_pmp;
 1043         struct direntry *dentp;
 1044         int gen;
 1045         int blsize;
 1046         u_long cn;
 1047         daddr_t bn;
 1048         struct buf *bp;
 1049         int error;
 1050         
 1051         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
 1052                 return (unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
 1053                     cnp->cn_namelen, 0, pmp) ? 0 : EINVAL);
 1054 
 1055         for (gen = 1;; gen++) {
 1056                 /*
 1057                  * Generate DOS name with generation number
 1058                  */
 1059                 if (!unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
 1060                     cnp->cn_namelen, gen, pmp))
 1061                         return gen == 1 ? EINVAL : EEXIST;
 1062 
 1063                 /*
 1064                  * Now look for a dir entry with this exact name
 1065                  */
 1066                 for (cn = error = 0; !error; cn++) {
 1067                         if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
 1068                                 if (error == E2BIG)     /* EOF reached and not found */
 1069                                         return 0;
 1070                                 return error;
 1071                         }
 1072                         error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
 1073                         if (error) {
 1074                                 brelse(bp);
 1075                                 return error;
 1076                         }
 1077                         for (dentp = (struct direntry *)bp->b_data;
 1078                              (char *)dentp < bp->b_data + blsize;
 1079                              dentp++) {
 1080                                 if (dentp->deName[0] == SLOT_EMPTY) {
 1081                                         /*
 1082                                          * Last used entry and not found
 1083                                          */
 1084                                         brelse(bp);
 1085                                         return 0;
 1086                                 }
 1087                                 /*
 1088                                  * Ignore volume labels and Win95 entries
 1089                                  */
 1090                                 if (dentp->deAttributes & ATTR_VOLUME)
 1091                                         continue;
 1092                                 if (!bcmp(dentp->deName, cp, 11)) {
 1093                                         error = EEXIST;
 1094                                         break;
 1095                                 }
 1096                         }
 1097                         brelse(bp);
 1098                 }
 1099         }
 1100 }
 1101 
 1102 /*
 1103  * Find any Win'95 long filename entry in directory dep
 1104  */
 1105 int
 1106 findwin95(dep)
 1107         struct denode *dep;
 1108 {
 1109         struct msdosfsmount *pmp = dep->de_pmp;
 1110         struct direntry *dentp;
 1111         int blsize, win95;
 1112         u_long cn;
 1113         daddr_t bn;
 1114         struct buf *bp;
 1115 
 1116         win95 = 1;
 1117         /*
 1118          * Read through the directory looking for Win'95 entries
 1119          * Note: Error currently handled just as EOF                    XXX
 1120          */
 1121         for (cn = 0;; cn++) {
 1122                 if (pcbmap(dep, cn, &bn, 0, &blsize))
 1123                         return (win95);
 1124                 if (bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) {
 1125                         brelse(bp);
 1126                         return (win95);
 1127                 }
 1128                 for (dentp = (struct direntry *)bp->b_data;
 1129                      (char *)dentp < bp->b_data + blsize;
 1130                      dentp++) {
 1131                         if (dentp->deName[0] == SLOT_EMPTY) {
 1132                                 /*
 1133                                  * Last used entry and not found
 1134                                  */
 1135                                 brelse(bp);
 1136                                 return (win95);
 1137                         }
 1138                         if (dentp->deName[0] == SLOT_DELETED) {
 1139                                 /*
 1140                                  * Ignore deleted files
 1141                                  * Note: might be an indication of Win'95 anyway        XXX
 1142                                  */
 1143                                 continue;
 1144                         }
 1145                         if (dentp->deAttributes == ATTR_WIN95) {
 1146                                 brelse(bp);
 1147                                 return 1;
 1148                         }
 1149                         win95 = 0;
 1150                 }
 1151                 brelse(bp);
 1152         }
 1153 }

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