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/6.1/sys/fs/msdosfs/msdosfs_lookup.c 145174 2005-04-16 23:47:19Z das $ */
    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 slotcount;
   94         int slotoffset = 0;
   95         int frcn;
   96         u_long cluster;
   97         int blkoff;
   98         int diroff;
   99         int blsize;
  100         int isadir;             /* ~0 if found direntry is a directory   */
  101         u_long scn;             /* starting cluster number               */
  102         struct vnode *pdp;
  103         struct denode *dp;
  104         struct denode *tdp;
  105         struct msdosfsmount *pmp;
  106         struct buf *bp = 0;
  107         struct direntry *dep = NULL;
  108         u_char dosfilename[12];
  109         int flags = cnp->cn_flags;
  110         int nameiop = cnp->cn_nameiop;
  111         struct thread *td = cnp->cn_thread;
  112         int unlen;
  113 
  114         int wincnt = 1;
  115         int chksum = -1, chksum_ok;
  116         int olddos = 1;
  117 
  118 #ifdef MSDOSFS_DEBUG
  119         printf("msdosfs_lookup(): looking for %s\n", cnp->cn_nameptr);
  120 #endif
  121         dp = VTODE(vdp);
  122         pmp = dp->de_pmp;
  123         *vpp = NULL;
  124 #ifdef MSDOSFS_DEBUG
  125         printf("msdosfs_lookup(): vdp %p, dp %p, Attr %02x\n",
  126             vdp, dp, dp->de_Attributes);
  127 #endif
  128 
  129         /*
  130          * If they are going after the . or .. entry in the root directory,
  131          * they won't find it.  DOS filesystems don't have them in the root
  132          * directory.  So, we fake it. deget() is in on this scam too.
  133          */
  134         if ((vdp->v_vflag & VV_ROOT) && cnp->cn_nameptr[0] == '.' &&
  135             (cnp->cn_namelen == 1 ||
  136                 (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.'))) {
  137                 isadir = ATTR_DIRECTORY;
  138                 scn = MSDOSFSROOT;
  139 #ifdef MSDOSFS_DEBUG
  140                 printf("msdosfs_lookup(): looking for . or .. in root directory\n");
  141 #endif
  142                 cluster = MSDOSFSROOT;
  143                 blkoff = MSDOSFSROOT_OFS;
  144                 goto foundroot;
  145         }
  146 
  147         switch (unix2dosfn((const u_char *)cnp->cn_nameptr, dosfilename,
  148             cnp->cn_namelen, 0, pmp)) {
  149         case 0:
  150                 return (EINVAL);
  151         case 1:
  152                 break;
  153         case 2:
  154                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  155                     cnp->cn_namelen, pmp) + 1;
  156                 break;
  157         case 3:
  158                 olddos = 0;
  159                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  160                     cnp->cn_namelen, pmp) + 1;
  161                 break;
  162         }
  163         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME) {
  164                 wincnt = 1;
  165                 olddos = 1;
  166         }
  167         unlen = winLenFixup(cnp->cn_nameptr, cnp->cn_namelen);
  168 
  169         /*
  170          * Suppress search for slots unless creating
  171          * file and at end of pathname, in which case
  172          * we watch for a place to put the new file in
  173          * case it doesn't already exist.
  174          */
  175         slotcount = wincnt;
  176         if ((nameiop == CREATE || nameiop == RENAME) &&
  177             (flags & ISLASTCN))
  178                 slotcount = 0;
  179 
  180 #ifdef MSDOSFS_DEBUG
  181         printf("msdosfs_lookup(): dos version of filename %s, length %ld\n",
  182             dosfilename, cnp->cn_namelen);
  183 #endif
  184         /*
  185          * Search the directory pointed at by vdp for the name pointed at
  186          * by cnp->cn_nameptr.
  187          */
  188         tdp = NULL;
  189         mbnambuf_init();
  190         /*
  191          * The outer loop ranges over the clusters that make up the
  192          * directory.  Note that the root directory is different from all
  193          * other directories.  It has a fixed number of blocks that are not
  194          * part of the pool of allocatable clusters.  So, we treat it a
  195          * little differently. The root directory starts at "cluster" 0.
  196          */
  197         diroff = 0;
  198         for (frcn = 0;; frcn++) {
  199                 error = pcbmap(dp, frcn, &bn, &cluster, &blsize);
  200                 if (error) {
  201                         if (error == E2BIG)
  202                                 break;
  203                         return (error);
  204                 }
  205                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  206                 if (error) {
  207                         brelse(bp);
  208                         return (error);
  209                 }
  210                 for (blkoff = 0; blkoff < blsize;
  211                      blkoff += sizeof(struct direntry),
  212                      diroff += sizeof(struct direntry)) {
  213                         dep = (struct direntry *)(bp->b_data + blkoff);
  214                         /*
  215                          * If the slot is empty and we are still looking
  216                          * for an empty then remember this one.  If the
  217                          * slot is not empty then check to see if it
  218                          * matches what we are looking for.  If the slot
  219                          * has never been filled with anything, then the
  220                          * remainder of the directory has never been used,
  221                          * so there is no point in searching it.
  222                          */
  223                         if (dep->deName[0] == SLOT_EMPTY ||
  224                             dep->deName[0] == SLOT_DELETED) {
  225                                 /*
  226                                  * Drop memory of previous long matches
  227                                  */
  228                                 chksum = -1;
  229                                 mbnambuf_init();
  230 
  231                                 if (slotcount < wincnt) {
  232                                         slotcount++;
  233                                         slotoffset = diroff;
  234                                 }
  235                                 if (dep->deName[0] == SLOT_EMPTY) {
  236                                         brelse(bp);
  237                                         goto notfound;
  238                                 }
  239                         } else {
  240                                 /*
  241                                  * If there wasn't enough space for our winentries,
  242                                  * forget about the empty space
  243                                  */
  244                                 if (slotcount < wincnt)
  245                                         slotcount = 0;
  246 
  247                                 /*
  248                                  * Check for Win95 long filename entry
  249                                  */
  250                                 if (dep->deAttributes == ATTR_WIN95) {
  251                                         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
  252                                                 continue;
  253 
  254                                         chksum = win2unixfn((struct winentry *)dep,
  255                                                             chksum,
  256                                                             pmp);
  257                                         continue;
  258                                 }
  259 
  260                                 chksum = winChkName((const u_char *)cnp->cn_nameptr,
  261                                                     unlen,
  262                                                     chksum,
  263                                                     pmp);
  264                                 if (chksum == -2) {
  265                                         chksum = -1;
  266                                         continue;
  267                                 }
  268 
  269                                 /*
  270                                  * Ignore volume labels (anywhere, not just
  271                                  * the root directory).
  272                                  */
  273                                 if (dep->deAttributes & ATTR_VOLUME) {
  274                                         chksum = -1;
  275                                         continue;
  276                                 }
  277 
  278                                 /*
  279                                  * Check for a checksum or name match
  280                                  */
  281                                 chksum_ok = (chksum == winChksum(dep->deName));
  282                                 if (!chksum_ok
  283                                     && (!olddos || bcmp(dosfilename, dep->deName, 11))) {
  284                                         chksum = -1;
  285                                         continue;
  286                                 }
  287 #ifdef MSDOSFS_DEBUG
  288                                 printf("msdosfs_lookup(): match blkoff %d, diroff %d\n",
  289                                     blkoff, diroff);
  290 #endif
  291                                 /*
  292                                  * Remember where this directory
  293                                  * entry came from for whoever did
  294                                  * this lookup.
  295                                  */
  296                                 dp->de_fndoffset = diroff;
  297                                 if (chksum_ok && nameiop == RENAME) {
  298                                         /*
  299                                          * Target had correct long name
  300                                          * directory entries, reuse them
  301                                          * as needed.
  302                                          */
  303                                         dp->de_fndcnt = wincnt - 1;
  304                                 } else {
  305                                         /*
  306                                          * Long name directory entries
  307                                          * not present or corrupt, can only
  308                                          * reuse dos directory entry.
  309                                          */
  310                                         dp->de_fndcnt = 0;
  311                                 }
  312 
  313                                 goto found;
  314                         }
  315                 }       /* for (blkoff = 0; .... */
  316                 /*
  317                  * Release the buffer holding the directory cluster just
  318                  * searched.
  319                  */
  320                 brelse(bp);
  321         }       /* for (frcn = 0; ; frcn++) */
  322 
  323 notfound:
  324         /*
  325          * We hold no disk buffers at this point.
  326          */
  327 
  328         /*
  329          * Fixup the slot description to point to the place where
  330          * we might put the new DOS direntry (putting the Win95
  331          * long name entries before that)
  332          */
  333         if (!slotcount) {
  334                 slotcount = 1;
  335                 slotoffset = diroff;
  336         }
  337         if (wincnt > slotcount)
  338                 slotoffset += sizeof(struct direntry) * (wincnt - slotcount);
  339 
  340         /*
  341          * If we get here we didn't find the entry we were looking for. But
  342          * that's ok if we are creating or renaming and are at the end of
  343          * the pathname and the directory hasn't been removed.
  344          */
  345 #ifdef MSDOSFS_DEBUG
  346         printf("msdosfs_lookup(): op %d, refcnt %ld\n",
  347             nameiop, dp->de_refcnt);
  348         printf("               slotcount %d, slotoffset %d\n",
  349                slotcount, slotoffset);
  350 #endif
  351         if ((nameiop == CREATE || nameiop == RENAME) &&
  352             (flags & ISLASTCN) && dp->de_refcnt != 0) {
  353                 /*
  354                  * Access for write is interpreted as allowing
  355                  * creation of files in the directory.
  356                  */
  357                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  358                 if (error)
  359                         return (error);
  360                 /*
  361                  * Return an indication of where the new directory
  362                  * entry should be put.
  363                  */
  364                 dp->de_fndoffset = slotoffset;
  365                 dp->de_fndcnt = wincnt - 1;
  366 
  367                 /*
  368                  * We return with the directory locked, so that
  369                  * the parameters we set up above will still be
  370                  * valid if we actually decide to do a direnter().
  371                  * We return ni_vp == NULL to indicate that the entry
  372                  * does not currently exist; we leave a pointer to
  373                  * the (locked) directory inode in ndp->ni_dvp.
  374                  * The pathname buffer is saved so that the name
  375                  * can be obtained later.
  376                  *
  377                  * NB - if the directory is unlocked, then this
  378                  * information cannot be used.
  379                  */
  380                 cnp->cn_flags |= SAVENAME;
  381                 return (EJUSTRETURN);
  382         }
  383 #if 0
  384         /*
  385          * Insert name into cache (as non-existent) if appropriate.
  386          *
  387          * XXX Negative caching is broken for msdosfs because the name
  388          * cache doesn't understand peculiarities such as case insensitivity
  389          * and 8.3 filenames.  Hence, it may not invalidate all negative
  390          * entries if a file with this name is later created.
  391          */
  392         if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
  393                 cache_enter(vdp, *vpp, cnp);
  394 #endif
  395         return (ENOENT);
  396 
  397 found:
  398         /*
  399          * NOTE:  We still have the buffer with matched directory entry at
  400          * this point.
  401          */
  402         isadir = dep->deAttributes & ATTR_DIRECTORY;
  403         scn = getushort(dep->deStartCluster);
  404         if (FAT32(pmp)) {
  405                 scn |= getushort(dep->deHighClust) << 16;
  406                 if (scn == pmp->pm_rootdirblk) {
  407                         /*
  408                          * There should actually be 0 here.
  409                          * Just ignore the error.
  410                          */
  411                         scn = MSDOSFSROOT;
  412                 }
  413         }
  414 
  415         if (isadir) {
  416                 cluster = scn;
  417                 if (cluster == MSDOSFSROOT)
  418                         blkoff = MSDOSFSROOT_OFS;
  419                 else
  420                         blkoff = 0;
  421         } else if (cluster == MSDOSFSROOT)
  422                 blkoff = diroff;
  423 
  424         /*
  425          * Now release buf to allow deget to read the entry again.
  426          * Reserving it here and giving it to deget could result
  427          * in a deadlock.
  428          */
  429         brelse(bp);
  430         bp = 0;
  431         
  432 foundroot:
  433         /*
  434          * If we entered at foundroot, then we are looking for the . or ..
  435          * entry of the filesystems root directory.  isadir and scn were
  436          * setup before jumping here.  And, bp is already null.
  437          */
  438         if (FAT32(pmp) && scn == MSDOSFSROOT)
  439                 scn = pmp->pm_rootdirblk;
  440 
  441         /*
  442          * If deleting, and at end of pathname, return
  443          * parameters which can be used to remove file.
  444          */
  445         if (nameiop == DELETE && (flags & ISLASTCN)) {
  446                 /*
  447                  * Don't allow deleting the root.
  448                  */
  449                 if (blkoff == MSDOSFSROOT_OFS)
  450                         return EROFS;                           /* really? XXX */
  451 
  452                 /*
  453                  * Write access to directory required to delete files.
  454                  */
  455                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  456                 if (error)
  457                         return (error);
  458 
  459                 /*
  460                  * Return pointer to current entry in dp->i_offset.
  461                  * Save directory inode pointer in ndp->ni_dvp for dirremove().
  462                  */
  463                 if (dp->de_StartCluster == scn && isadir) {     /* "." */
  464                         VREF(vdp);
  465                         *vpp = vdp;
  466                         return (0);
  467                 }
  468                 error = deget(pmp, cluster, blkoff, &tdp);
  469                 if (error)
  470                         return (error);
  471                 *vpp = DETOV(tdp);
  472                 return (0);
  473         }
  474 
  475         /*
  476          * If rewriting (RENAME), return the inode and the
  477          * information required to rewrite the present directory
  478          * Must get inode of directory entry to verify it's a
  479          * regular file, or empty directory.
  480          */
  481         if (nameiop == RENAME && (flags & ISLASTCN)) {
  482                 if (blkoff == MSDOSFSROOT_OFS)
  483                         return EROFS;                           /* really? XXX */
  484 
  485                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_thread);
  486                 if (error)
  487                         return (error);
  488 
  489                 /*
  490                  * Careful about locking second inode.
  491                  * This can only occur if the target is ".".
  492                  */
  493                 if (dp->de_StartCluster == scn && isadir)
  494                         return (EISDIR);
  495 
  496                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  497                         return (error);
  498                 *vpp = DETOV(tdp);
  499                 cnp->cn_flags |= SAVENAME;
  500                 return (0);
  501         }
  502 
  503         /*
  504          * Step through the translation in the name.  We do not `vput' the
  505          * directory because we may need it again if a symbolic link
  506          * is relative to the current directory.  Instead we save it
  507          * unlocked as "pdp".  We must get the target inode before unlocking
  508          * the directory to insure that the inode will not be removed
  509          * before we get it.  We prevent deadlock by always fetching
  510          * inodes from the root, moving down the directory tree. Thus
  511          * when following backward pointers ".." we must unlock the
  512          * parent directory before getting the requested directory.
  513          * There is a potential race condition here if both the current
  514          * and parent directories are removed before the VFS_VGET for the
  515          * inode associated with ".." returns.  We hope that this occurs
  516          * infrequently since we cannot avoid this race condition without
  517          * implementing a sophisticated deadlock detection algorithm.
  518          * Note also that this simple deadlock detection scheme will not
  519          * work if the filesystem has any hard links other than ".."
  520          * that point backwards in the directory structure.
  521          */
  522         pdp = vdp;
  523         if (flags & ISDOTDOT) {
  524                 VOP_UNLOCK(pdp, 0, td);
  525                 error = deget(pmp, cluster, blkoff,  &tdp);
  526                 vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, td); 
  527                 if (error)
  528                         return (error);
  529                 *vpp = DETOV(tdp);
  530         } else if (dp->de_StartCluster == scn && isadir) {
  531                 VREF(vdp);      /* we want ourself, ie "." */
  532                 *vpp = vdp;
  533         } else {
  534                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  535                         return (error);
  536                 *vpp = DETOV(tdp);
  537         }
  538 
  539         /*
  540          * Insert name into cache if appropriate.
  541          */
  542         if (cnp->cn_flags & MAKEENTRY)
  543                 cache_enter(vdp, *vpp, cnp);
  544         return (0);
  545 }
  546 
  547 /*
  548  * dep  - directory entry to copy into the directory
  549  * ddep - directory to add to
  550  * depp - return the address of the denode for the created directory entry
  551  *        if depp != 0
  552  * cnp  - componentname needed for Win95 long filenames
  553  */
  554 int
  555 createde(dep, ddep, depp, cnp)
  556         struct denode *dep;
  557         struct denode *ddep;
  558         struct denode **depp;
  559         struct componentname *cnp;
  560 {
  561         int error;
  562         u_long dirclust, diroffset;
  563         struct direntry *ndep;
  564         struct msdosfsmount *pmp = ddep->de_pmp;
  565         struct buf *bp;
  566         daddr_t bn;
  567         int blsize;
  568 
  569 #ifdef MSDOSFS_DEBUG
  570         printf("createde(dep %p, ddep %p, depp %p, cnp %p)\n",
  571             dep, ddep, depp, cnp);
  572 #endif
  573 
  574         /*
  575          * If no space left in the directory then allocate another cluster
  576          * and chain it onto the end of the file.  There is one exception
  577          * to this.  That is, if the root directory has no more space it
  578          * can NOT be expanded.  extendfile() checks for and fails attempts
  579          * to extend the root directory.  We just return an error in that
  580          * case.
  581          */
  582         if (ddep->de_fndoffset >= ddep->de_FileSize) {
  583                 diroffset = ddep->de_fndoffset + sizeof(struct direntry)
  584                     - ddep->de_FileSize;
  585                 dirclust = de_clcount(pmp, diroffset);
  586                 error = extendfile(ddep, dirclust, 0, 0, DE_CLEAR);
  587                 if (error) {
  588                         (void)detrunc(ddep, ddep->de_FileSize, 0, NOCRED, NULL);
  589                         return error;
  590                 }
  591 
  592                 /*
  593                  * Update the size of the directory
  594                  */
  595                 ddep->de_FileSize += de_cn2off(pmp, dirclust);
  596         }
  597 
  598         /*
  599          * We just read in the cluster with space.  Copy the new directory
  600          * entry in.  Then write it to disk. NOTE:  DOS directories
  601          * do not get smaller as clusters are emptied.
  602          */
  603         error = pcbmap(ddep, de_cluster(pmp, ddep->de_fndoffset),
  604                        &bn, &dirclust, &blsize);
  605         if (error)
  606                 return error;
  607         diroffset = ddep->de_fndoffset;
  608         if (dirclust != MSDOSFSROOT)
  609                 diroffset &= pmp->pm_crbomask;
  610         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) != 0) {
  611                 brelse(bp);
  612                 return error;
  613         }
  614         ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  615 
  616         DE_EXTERNALIZE(ndep, dep);
  617 
  618         /*
  619          * Now write the Win95 long name
  620          */
  621         if (ddep->de_fndcnt > 0) {
  622                 u_int8_t chksum = winChksum(ndep->deName);
  623                 const u_char *un = (const u_char *)cnp->cn_nameptr;
  624                 int unlen = cnp->cn_namelen;
  625                 int cnt = 1;
  626 
  627                 while (--ddep->de_fndcnt >= 0) {
  628                         if (!(ddep->de_fndoffset & pmp->pm_crbomask)) {
  629                                 if ((error = bwrite(bp)) != 0)
  630                                         return error;
  631 
  632                                 ddep->de_fndoffset -= sizeof(struct direntry);
  633                                 error = pcbmap(ddep,
  634                                                de_cluster(pmp,
  635                                                           ddep->de_fndoffset),
  636                                                &bn, 0, &blsize);
  637                                 if (error)
  638                                         return error;
  639 
  640                                 error = bread(pmp->pm_devvp, bn, blsize,
  641                                               NOCRED, &bp);
  642                                 if (error) {
  643                                         brelse(bp);
  644                                         return error;
  645                                 }
  646                                 ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  647                         } else {
  648                                 ndep--;
  649                                 ddep->de_fndoffset -= sizeof(struct direntry);
  650                         }
  651                         if (!unix2winfn(un, unlen, (struct winentry *)ndep,
  652                                         cnt++, chksum, pmp))
  653                                 break;
  654                 }
  655         }
  656 
  657         if ((error = bwrite(bp)) != 0)
  658                 return error;
  659 
  660         /*
  661          * If they want us to return with the denode gotten.
  662          */
  663         if (depp) {
  664                 if (dep->de_Attributes & ATTR_DIRECTORY) {
  665                         dirclust = dep->de_StartCluster;
  666                         if (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)
  667                                 dirclust = MSDOSFSROOT;
  668                         if (dirclust == MSDOSFSROOT)
  669                                 diroffset = MSDOSFSROOT_OFS;
  670                         else
  671                                 diroffset = 0;
  672                 }
  673                 return deget(pmp, dirclust, diroffset, depp);
  674         }
  675 
  676         return 0;
  677 }
  678 
  679 /*
  680  * Be sure a directory is empty except for "." and "..". Return 1 if empty,
  681  * return 0 if not empty or error.
  682  */
  683 int
  684 dosdirempty(dep)
  685         struct denode *dep;
  686 {
  687         int blsize;
  688         int error;
  689         u_long cn;
  690         daddr_t bn;
  691         struct buf *bp;
  692         struct msdosfsmount *pmp = dep->de_pmp;
  693         struct direntry *dentp;
  694 
  695         /*
  696          * Since the filesize field in directory entries for a directory is
  697          * zero, we just have to feel our way through the directory until
  698          * we hit end of file.
  699          */
  700         for (cn = 0;; cn++) {
  701                 if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
  702                         if (error == E2BIG)
  703                                 return (1);     /* it's empty */
  704                         return (0);
  705                 }
  706                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  707                 if (error) {
  708                         brelse(bp);
  709                         return (0);
  710                 }
  711                 for (dentp = (struct direntry *)bp->b_data;
  712                      (char *)dentp < bp->b_data + blsize;
  713                      dentp++) {
  714                         if (dentp->deName[0] != SLOT_DELETED &&
  715                             (dentp->deAttributes & ATTR_VOLUME) == 0) {
  716                                 /*
  717                                  * In dos directories an entry whose name
  718                                  * starts with SLOT_EMPTY (0) starts the
  719                                  * beginning of the unused part of the
  720                                  * directory, so we can just return that it
  721                                  * is empty.
  722                                  */
  723                                 if (dentp->deName[0] == SLOT_EMPTY) {
  724                                         brelse(bp);
  725                                         return (1);
  726                                 }
  727                                 /*
  728                                  * Any names other than "." and ".." in a
  729                                  * directory mean it is not empty.
  730                                  */
  731                                 if (bcmp(dentp->deName, ".          ", 11) &&
  732                                     bcmp(dentp->deName, "..         ", 11)) {
  733                                         brelse(bp);
  734 #ifdef MSDOSFS_DEBUG
  735                                         printf("dosdirempty(): entry found %02x, %02x\n",
  736                                             dentp->deName[0], dentp->deName[1]);
  737 #endif
  738                                         return (0);     /* not empty */
  739                                 }
  740                         }
  741                 }
  742                 brelse(bp);
  743         }
  744         /* NOTREACHED */
  745 }
  746 
  747 /*
  748  * Check to see if the directory described by target is in some
  749  * subdirectory of source.  This prevents something like the following from
  750  * succeeding and leaving a bunch or files and directories orphaned. mv
  751  * /a/b/c /a/b/c/d/e/f Where c and f are directories.
  752  *
  753  * source - the inode for /a/b/c
  754  * target - the inode for /a/b/c/d/e/f
  755  *
  756  * Returns 0 if target is NOT a subdirectory of source.
  757  * Otherwise returns a non-zero error number.
  758  * The target inode is always unlocked on return.
  759  */
  760 int
  761 doscheckpath(source, target)
  762         struct denode *source;
  763         struct denode *target;
  764 {
  765         daddr_t scn;
  766         struct msdosfsmount *pmp;
  767         struct direntry *ep;
  768         struct denode *dep;
  769         struct buf *bp = NULL;
  770         int error = 0;
  771 
  772         dep = target;
  773         if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
  774             (source->de_Attributes & ATTR_DIRECTORY) == 0) {
  775                 error = ENOTDIR;
  776                 goto out;
  777         }
  778         if (dep->de_StartCluster == source->de_StartCluster) {
  779                 error = EEXIST;
  780                 goto out;
  781         }
  782         if (dep->de_StartCluster == MSDOSFSROOT)
  783                 goto out;
  784         pmp = dep->de_pmp;
  785 #ifdef  DIAGNOSTIC
  786         if (pmp != source->de_pmp)
  787                 panic("doscheckpath: source and target on different filesystems");
  788 #endif
  789         if (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)
  790                 goto out;
  791 
  792         for (;;) {
  793                 if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
  794                         error = ENOTDIR;
  795                         break;
  796                 }
  797                 scn = dep->de_StartCluster;
  798                 error = bread(pmp->pm_devvp, cntobn(pmp, scn),
  799                               pmp->pm_bpcluster, NOCRED, &bp);
  800                 if (error)
  801                         break;
  802 
  803                 ep = (struct direntry *) bp->b_data + 1;
  804                 if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
  805                     bcmp(ep->deName, "..         ", 11) != 0) {
  806                         error = ENOTDIR;
  807                         break;
  808                 }
  809                 scn = getushort(ep->deStartCluster);
  810                 if (FAT32(pmp))
  811                         scn |= getushort(ep->deHighClust) << 16;
  812 
  813                 if (scn == source->de_StartCluster) {
  814                         error = EINVAL;
  815                         break;
  816                 }
  817                 if (scn == MSDOSFSROOT)
  818                         break;
  819                 if (FAT32(pmp) && scn == pmp->pm_rootdirblk) {
  820                         /*
  821                          * scn should be 0 in this case,
  822                          * but we silently ignore the error.
  823                          */
  824                         break;
  825                 }
  826 
  827                 vput(DETOV(dep));
  828                 brelse(bp);
  829                 bp = NULL;
  830                 /* NOTE: deget() clears dep on error */
  831                 if ((error = deget(pmp, scn, 0, &dep)) != 0)
  832                         break;
  833         }
  834 out:;
  835         if (bp)
  836                 brelse(bp);
  837         if (error == ENOTDIR)
  838                 printf("doscheckpath(): .. not a directory?\n");
  839         if (dep != NULL)
  840                 vput(DETOV(dep));
  841         return (error);
  842 }
  843 
  844 /*
  845  * Read in the disk block containing the directory entry (dirclu, dirofs)
  846  * and return the address of the buf header, and the address of the
  847  * directory entry within the block.
  848  */
  849 int
  850 readep(pmp, dirclust, diroffset, bpp, epp)
  851         struct msdosfsmount *pmp;
  852         u_long dirclust, diroffset;
  853         struct buf **bpp;
  854         struct direntry **epp;
  855 {
  856         int error;
  857         daddr_t bn;
  858         int blsize;
  859 
  860         blsize = pmp->pm_bpcluster;
  861         if (dirclust == MSDOSFSROOT
  862             && de_blk(pmp, diroffset + blsize) > pmp->pm_rootdirsize)
  863                 blsize = de_bn2off(pmp, pmp->pm_rootdirsize) & pmp->pm_crbomask;
  864         bn = detobn(pmp, dirclust, diroffset);
  865         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, bpp)) != 0) {
  866                 brelse(*bpp);
  867                 *bpp = NULL;
  868                 return (error);
  869         }
  870         if (epp)
  871                 *epp = bptoep(pmp, *bpp, diroffset);
  872         return (0);
  873 }
  874 
  875 /*
  876  * Read in the disk block containing the directory entry dep came from and
  877  * return the address of the buf header, and the address of the directory
  878  * entry within the block.
  879  */
  880 int
  881 readde(dep, bpp, epp)
  882         struct denode *dep;
  883         struct buf **bpp;
  884         struct direntry **epp;
  885 {
  886 
  887         return (readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
  888             bpp, epp));
  889 }
  890 
  891 /*
  892  * Remove a directory entry. At this point the file represented by the
  893  * directory entry to be removed is still full length until noone has it
  894  * open.  When the file no longer being used msdosfs_inactive() is called
  895  * and will truncate the file to 0 length.  When the vnode containing the
  896  * denode is needed for some other purpose by VFS it will call
  897  * msdosfs_reclaim() which will remove the denode from the denode cache.
  898  */
  899 int
  900 removede(pdep, dep)
  901         struct denode *pdep;    /* directory where the entry is removed */
  902         struct denode *dep;     /* file to be removed */
  903 {
  904         int error;
  905         struct direntry *ep;
  906         struct buf *bp;
  907         daddr_t bn;
  908         int blsize;
  909         struct msdosfsmount *pmp = pdep->de_pmp;
  910         u_long offset = pdep->de_fndoffset;
  911 
  912 #ifdef MSDOSFS_DEBUG
  913         printf("removede(): filename %s, dep %p, offset %08lx\n",
  914             dep->de_Name, dep, offset);
  915 #endif
  916 
  917         dep->de_refcnt--;
  918         offset += sizeof(struct direntry);
  919         do {
  920                 offset -= sizeof(struct direntry);
  921                 error = pcbmap(pdep, de_cluster(pmp, offset), &bn, 0, &blsize);
  922                 if (error)
  923                         return error;
  924                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  925                 if (error) {
  926                         brelse(bp);
  927                         return error;
  928                 }
  929                 ep = bptoep(pmp, bp, offset);
  930                 /*
  931                  * Check whether, if we came here the second time, i.e.
  932                  * when underflowing into the previous block, the last
  933                  * entry in this block is a longfilename entry, too.
  934                  */
  935                 if (ep->deAttributes != ATTR_WIN95
  936                     && offset != pdep->de_fndoffset) {
  937                         brelse(bp);
  938                         break;
  939                 }
  940                 offset += sizeof(struct direntry);
  941                 while (1) {
  942                         /*
  943                          * We are a bit agressive here in that we delete any Win95
  944                          * entries preceding this entry, not just the ones we "own".
  945                          * Since these presumably aren't valid anyway,
  946                          * there should be no harm.
  947                          */
  948                         offset -= sizeof(struct direntry);
  949                         ep--->deName[0] = SLOT_DELETED;
  950                         if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95)
  951                             || !(offset & pmp->pm_crbomask)
  952                             || ep->deAttributes != ATTR_WIN95)
  953                                 break;
  954                 }
  955                 if ((error = bwrite(bp)) != 0)
  956                         return error;
  957         } while (!(pmp->pm_flags & MSDOSFSMNT_NOWIN95)
  958             && !(offset & pmp->pm_crbomask)
  959             && offset);
  960         return 0;
  961 }
  962 
  963 /*
  964  * Create a unique DOS name in dvp
  965  */
  966 int
  967 uniqdosname(dep, cnp, cp)
  968         struct denode *dep;
  969         struct componentname *cnp;
  970         u_char *cp;
  971 {
  972         struct msdosfsmount *pmp = dep->de_pmp;
  973         struct direntry *dentp;
  974         int gen;
  975         int blsize;
  976         u_long cn;
  977         daddr_t bn;
  978         struct buf *bp;
  979         int error;
  980         
  981         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
  982                 return (unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
  983                     cnp->cn_namelen, 0, pmp) ? 0 : EINVAL);
  984 
  985         for (gen = 1;; gen++) {
  986                 /*
  987                  * Generate DOS name with generation number
  988                  */
  989                 if (!unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
  990                     cnp->cn_namelen, gen, pmp))
  991                         return gen == 1 ? EINVAL : EEXIST;
  992 
  993                 /*
  994                  * Now look for a dir entry with this exact name
  995                  */
  996                 for (cn = error = 0; !error; cn++) {
  997                         if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
  998                                 if (error == E2BIG)     /* EOF reached and not found */
  999                                         return 0;
 1000                                 return error;
 1001                         }
 1002                         error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
 1003                         if (error) {
 1004                                 brelse(bp);
 1005                                 return error;
 1006                         }
 1007                         for (dentp = (struct direntry *)bp->b_data;
 1008                              (char *)dentp < bp->b_data + blsize;
 1009                              dentp++) {
 1010                                 if (dentp->deName[0] == SLOT_EMPTY) {
 1011                                         /*
 1012                                          * Last used entry and not found
 1013                                          */
 1014                                         brelse(bp);
 1015                                         return 0;
 1016                                 }
 1017                                 /*
 1018                                  * Ignore volume labels and Win95 entries
 1019                                  */
 1020                                 if (dentp->deAttributes & ATTR_VOLUME)
 1021                                         continue;
 1022                                 if (!bcmp(dentp->deName, cp, 11)) {
 1023                                         error = EEXIST;
 1024                                         break;
 1025                                 }
 1026                         }
 1027                         brelse(bp);
 1028                 }
 1029         }
 1030 }
 1031 
 1032 /*
 1033  * Find any Win'95 long filename entry in directory dep
 1034  */
 1035 int
 1036 findwin95(dep)
 1037         struct denode *dep;
 1038 {
 1039         struct msdosfsmount *pmp = dep->de_pmp;
 1040         struct direntry *dentp;
 1041         int blsize, win95;
 1042         u_long cn;
 1043         daddr_t bn;
 1044         struct buf *bp;
 1045 
 1046         win95 = 1;
 1047         /*
 1048          * Read through the directory looking for Win'95 entries
 1049          * Note: Error currently handled just as EOF                    XXX
 1050          */
 1051         for (cn = 0;; cn++) {
 1052                 if (pcbmap(dep, cn, &bn, 0, &blsize))
 1053                         return (win95);
 1054                 if (bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) {
 1055                         brelse(bp);
 1056                         return (win95);
 1057                 }
 1058                 for (dentp = (struct direntry *)bp->b_data;
 1059                      (char *)dentp < bp->b_data + blsize;
 1060                      dentp++) {
 1061                         if (dentp->deName[0] == SLOT_EMPTY) {
 1062                                 /*
 1063                                  * Last used entry and not found
 1064                                  */
 1065                                 brelse(bp);
 1066                                 return (win95);
 1067                         }
 1068                         if (dentp->deName[0] == SLOT_DELETED) {
 1069                                 /*
 1070                                  * Ignore deleted files
 1071                                  * Note: might be an indication of Win'95 anyway        XXX
 1072                                  */
 1073                                 continue;
 1074                         }
 1075                         if (dentp->deAttributes == ATTR_WIN95) {
 1076                                 brelse(bp);
 1077                                 return 1;
 1078                         }
 1079                         win95 = 0;
 1080                 }
 1081                 brelse(bp);
 1082         }
 1083 }

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