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

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    1 /* $FreeBSD$ */
    2 /*      $NetBSD: msdosfs_lookup.c,v 1.37 1997/11/17 15:36:54 ws Exp $   */
    3 
    4 /*-
    5  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
    6  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
    7  * All rights reserved.
    8  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by TooLs GmbH.
   21  * 4. The name of TooLs GmbH may not be used to endorse or promote products
   22  *    derived from this software without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
   25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   27  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   29  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   30  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   31  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   32  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   33  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   34  */
   35 /*
   36  * Written by Paul Popelka (paulp@uts.amdahl.com)
   37  *
   38  * You can do anything you want with this software, just don't say you wrote
   39  * it, and don't remove this notice.
   40  *
   41  * This software is provided "as is".
   42  *
   43  * The author supplies this software to be publicly redistributed on the
   44  * understanding that the author is not responsible for the correct
   45  * functioning of this software in any circumstances and is not liable for
   46  * any damages caused by this software.
   47  *
   48  * October 1992
   49  */
   50 
   51 #include <sys/param.h>
   52 #include <sys/namei.h>
   53 #include <sys/buf.h>
   54 #include <sys/vnode.h>
   55 #include <sys/mount.h>
   56 #include <sys/systm.h>
   57 
   58 #include <msdosfs/bpb.h>
   59 #include <msdosfs/direntry.h>
   60 #include <msdosfs/denode.h>
   61 #include <msdosfs/msdosfsmount.h>
   62 #include <msdosfs/fat.h>
   63 
   64 /*
   65  * When we search a directory the blocks containing directory entries are
   66  * read and examined.  The directory entries contain information that would
   67  * normally be in the inode of a unix filesystem.  This means that some of
   68  * a directory's contents may also be in memory resident denodes (sort of
   69  * an inode).  This can cause problems if we are searching while some other
   70  * process is modifying a directory.  To prevent one process from accessing
   71  * incompletely modified directory information we depend upon being the
   72  * sole owner of a directory block.  bread/brelse provide this service.
   73  * This being the case, when a process modifies a directory it must first
   74  * acquire the disk block that contains the directory entry to be modified.
   75  * Then update the disk block and the denode, and then write the disk block
   76  * out to disk.  This way disk blocks containing directory entries and in
   77  * memory denode's will be in synch.
   78  */
   79 int
   80 msdosfs_lookup(ap)
   81         struct vop_cachedlookup_args /* {
   82                 struct vnode *a_dvp;
   83                 struct vnode **a_vpp;
   84                 struct componentname *a_cnp;
   85         } */ *ap;
   86 {
   87         struct vnode *vdp = ap->a_dvp;
   88         struct vnode **vpp = ap->a_vpp;
   89         struct componentname *cnp = ap->a_cnp;
   90         daddr_t bn;
   91         int error;
   92         int lockparent;
   93         int wantparent;
   94         int slotcount;
   95         int slotoffset = 0;
   96         int frcn;
   97         u_long cluster;
   98         int blkoff;
   99         int diroff;
  100         int blsize;
  101         int isadir;             /* ~0 if found direntry is a directory   */
  102         u_long scn;             /* starting cluster number               */
  103         struct vnode *pdp;
  104         struct denode *dp;
  105         struct denode *tdp;
  106         struct msdosfsmount *pmp;
  107         struct buf *bp = 0;
  108         struct direntry *dep = NULL;
  109         u_char dosfilename[12];
  110         int flags = cnp->cn_flags;
  111         int nameiop = cnp->cn_nameiop;
  112         struct proc *p = cnp->cn_proc;
  113         int unlen;
  114 
  115         int wincnt = 1;
  116         int chksum = -1;
  117         int olddos = 1;
  118 
  119 #ifdef MSDOSFS_DEBUG
  120         printf("msdosfs_lookup(): looking for %s\n", cnp->cn_nameptr);
  121 #endif
  122         dp = VTODE(vdp);
  123         pmp = dp->de_pmp;
  124         *vpp = NULL;
  125         lockparent = flags & LOCKPARENT;
  126         wantparent = flags & (LOCKPARENT | WANTPARENT);
  127 #ifdef MSDOSFS_DEBUG
  128         printf("msdosfs_lookup(): vdp %p, dp %p, Attr %02x\n",
  129             vdp, dp, dp->de_Attributes);
  130 #endif
  131 
  132         /*
  133          * If they are going after the . or .. entry in the root directory,
  134          * they won't find it.  DOS filesystems don't have them in the root
  135          * directory.  So, we fake it. deget() is in on this scam too.
  136          */
  137         if ((vdp->v_flag & VROOT) && cnp->cn_nameptr[0] == '.' &&
  138             (cnp->cn_namelen == 1 ||
  139                 (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.'))) {
  140                 isadir = ATTR_DIRECTORY;
  141                 scn = MSDOSFSROOT;
  142 #ifdef MSDOSFS_DEBUG
  143                 printf("msdosfs_lookup(): looking for . or .. in root directory\n");
  144 #endif
  145                 cluster = MSDOSFSROOT;
  146                 blkoff = MSDOSFSROOT_OFS;
  147                 goto foundroot;
  148         }
  149 
  150         switch (unix2dosfn((const u_char *)cnp->cn_nameptr, dosfilename,
  151             cnp->cn_namelen, 0,
  152             pmp->pm_flags & MSDOSFSMNT_U2WTABLE, pmp->pm_u2d,
  153             pmp->pm_flags & MSDOSFSMNT_ULTABLE, pmp->pm_lu)) {
  154         case 0:
  155                 return (EINVAL);
  156         case 1:
  157                 break;
  158         case 2:
  159                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  160                     cnp->cn_namelen) + 1;
  161                 break;
  162         case 3:
  163                 olddos = 0;
  164                 wincnt = winSlotCnt((const u_char *)cnp->cn_nameptr,
  165                     cnp->cn_namelen) + 1;
  166                 break;
  167         }
  168         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME) {
  169                 wincnt = 1;
  170                 olddos = 1;
  171         }
  172         unlen = winLenFixup(cnp->cn_nameptr, cnp->cn_namelen);
  173 
  174         /*
  175          * Suppress search for slots unless creating
  176          * file and at end of pathname, in which case
  177          * we watch for a place to put the new file in
  178          * case it doesn't already exist.
  179          */
  180         slotcount = wincnt;
  181         if ((nameiop == CREATE || nameiop == RENAME) &&
  182             (flags & ISLASTCN))
  183                 slotcount = 0;
  184 
  185 #ifdef MSDOSFS_DEBUG
  186         printf("msdosfs_lookup(): dos version of filename %s, length %ld\n",
  187             dosfilename, cnp->cn_namelen);
  188 #endif
  189         /*
  190          * Search the directory pointed at by vdp for the name pointed at
  191          * by cnp->cn_nameptr.
  192          */
  193         tdp = NULL;
  194         /*
  195          * The outer loop ranges over the clusters that make up the
  196          * directory.  Note that the root directory is different from all
  197          * other directories.  It has a fixed number of blocks that are not
  198          * part of the pool of allocatable clusters.  So, we treat it a
  199          * little differently. The root directory starts at "cluster" 0.
  200          */
  201         diroff = 0;
  202         for (frcn = 0;; frcn++) {
  203                 error = pcbmap(dp, frcn, &bn, &cluster, &blsize);
  204                 if (error) {
  205                         if (error == E2BIG)
  206                                 break;
  207                         return (error);
  208                 }
  209                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  210                 if (error) {
  211                         brelse(bp);
  212                         return (error);
  213                 }
  214                 for (blkoff = 0; blkoff < blsize;
  215                      blkoff += sizeof(struct direntry),
  216                      diroff += sizeof(struct direntry)) {
  217                         dep = (struct direntry *)(bp->b_data + blkoff);
  218                         /*
  219                          * If the slot is empty and we are still looking
  220                          * for an empty then remember this one.  If the
  221                          * slot is not empty then check to see if it
  222                          * matches what we are looking for.  If the slot
  223                          * has never been filled with anything, then the
  224                          * remainder of the directory has never been used,
  225                          * so there is no point in searching it.
  226                          */
  227                         if (dep->deName[0] == SLOT_EMPTY ||
  228                             dep->deName[0] == SLOT_DELETED) {
  229                                 /*
  230                                  * Drop memory of previous long matches
  231                                  */
  232                                 chksum = -1;
  233 
  234                                 if (slotcount < wincnt) {
  235                                         slotcount++;
  236                                         slotoffset = diroff;
  237                                 }
  238                                 if (dep->deName[0] == SLOT_EMPTY) {
  239                                         brelse(bp);
  240                                         goto notfound;
  241                                 }
  242                         } else {
  243                                 /*
  244                                  * If there wasn't enough space for our winentries,
  245                                  * forget about the empty space
  246                                  */
  247                                 if (slotcount < wincnt)
  248                                         slotcount = 0;
  249 
  250                                 /*
  251                                  * Check for Win95 long filename entry
  252                                  */
  253                                 if (dep->deAttributes == ATTR_WIN95) {
  254                                         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
  255                                                 continue;
  256 
  257                                         chksum = winChkName((const u_char *)cnp->cn_nameptr,
  258                                                             unlen,
  259                                                             (struct winentry *)dep,
  260                                                             chksum,
  261                                                             pmp->pm_flags & MSDOSFSMNT_U2WTABLE,
  262                                                             pmp->pm_u2w,
  263                                                             pmp->pm_flags & MSDOSFSMNT_ULTABLE,
  264                                                             pmp->pm_ul);
  265                                         continue;
  266                                 }
  267 
  268                                 /*
  269                                  * Ignore volume labels (anywhere, not just
  270                                  * the root directory).
  271                                  */
  272                                 if (dep->deAttributes & ATTR_VOLUME) {
  273                                         chksum = -1;
  274                                         continue;
  275                                 }
  276 
  277                                 /*
  278                                  * Check for a checksum or name match
  279                                  */
  280                                 if (chksum != winChksum(dep->deName)
  281                                     && (!olddos || bcmp(dosfilename, dep->deName, 11))) {
  282                                         chksum = -1;
  283                                         continue;
  284                                 }
  285 #ifdef MSDOSFS_DEBUG
  286                                 printf("msdosfs_lookup(): match blkoff %d, diroff %d\n",
  287                                     blkoff, diroff);
  288 #endif
  289                                 /*
  290                                  * Remember where this directory
  291                                  * entry came from for whoever did
  292                                  * this lookup.
  293                                  */
  294                                 dp->de_fndoffset = diroff;
  295                                 dp->de_fndcnt = wincnt - 1;
  296 
  297                                 goto found;
  298                         }
  299                 }       /* for (blkoff = 0; .... */
  300                 /*
  301                  * Release the buffer holding the directory cluster just
  302                  * searched.
  303                  */
  304                 brelse(bp);
  305         }       /* for (frcn = 0; ; frcn++) */
  306 
  307 notfound:
  308         /*
  309          * We hold no disk buffers at this point.
  310          */
  311 
  312         /*
  313          * Fixup the slot description to point to the place where
  314          * we might put the new DOS direntry (putting the Win95
  315          * long name entries before that)
  316          */
  317         if (!slotcount) {
  318                 slotcount = 1;
  319                 slotoffset = diroff;
  320         }
  321         if (wincnt > slotcount)
  322                 slotoffset += sizeof(struct direntry) * (wincnt - slotcount);
  323 
  324         /*
  325          * If we get here we didn't find the entry we were looking for. But
  326          * that's ok if we are creating or renaming and are at the end of
  327          * the pathname and the directory hasn't been removed.
  328          */
  329 #ifdef MSDOSFS_DEBUG
  330         printf("msdosfs_lookup(): op %d, refcnt %ld\n",
  331             nameiop, dp->de_refcnt);
  332         printf("               slotcount %d, slotoffset %d\n",
  333                slotcount, slotoffset);
  334 #endif
  335         if ((nameiop == CREATE || nameiop == RENAME) &&
  336             (flags & ISLASTCN) && dp->de_refcnt != 0) {
  337                 /*
  338                  * Access for write is interpreted as allowing
  339                  * creation of files in the directory.
  340                  */
  341                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_proc);
  342                 if (error)
  343                         return (error);
  344                 /*
  345                  * Return an indication of where the new directory
  346                  * entry should be put.
  347                  */
  348                 dp->de_fndoffset = slotoffset;
  349                 dp->de_fndcnt = wincnt - 1;
  350 
  351                 /*
  352                  * We return with the directory locked, so that
  353                  * the parameters we set up above will still be
  354                  * valid if we actually decide to do a direnter().
  355                  * We return ni_vp == NULL to indicate that the entry
  356                  * does not currently exist; we leave a pointer to
  357                  * the (locked) directory inode in ndp->ni_dvp.
  358                  * The pathname buffer is saved so that the name
  359                  * can be obtained later.
  360                  *
  361                  * NB - if the directory is unlocked, then this
  362                  * information cannot be used.
  363                  */
  364                 cnp->cn_flags |= SAVENAME;
  365                 if (!lockparent)
  366                         VOP_UNLOCK(vdp, 0, p);
  367                 return (EJUSTRETURN);
  368         }
  369         /*
  370          * Insert name into cache (as non-existent) if appropriate.
  371          */
  372         if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
  373                 cache_enter(vdp, *vpp, cnp);
  374         return (ENOENT);
  375 
  376 found:
  377         /*
  378          * NOTE:  We still have the buffer with matched directory entry at
  379          * this point.
  380          */
  381         isadir = dep->deAttributes & ATTR_DIRECTORY;
  382         scn = getushort(dep->deStartCluster);
  383         if (FAT32(pmp)) {
  384                 scn |= getushort(dep->deHighClust) << 16;
  385                 if (scn == pmp->pm_rootdirblk) {
  386                         /*
  387                          * There should actually be 0 here.
  388                          * Just ignore the error.
  389                          */
  390                         scn = MSDOSFSROOT;
  391                 }
  392         }
  393 
  394         if (isadir) {
  395                 cluster = scn;
  396                 if (cluster == MSDOSFSROOT)
  397                         blkoff = MSDOSFSROOT_OFS;
  398                 else
  399                         blkoff = 0;
  400         } else if (cluster == MSDOSFSROOT)
  401                 blkoff = diroff;
  402 
  403         /*
  404          * Now release buf to allow deget to read the entry again.
  405          * Reserving it here and giving it to deget could result
  406          * in a deadlock.
  407          */
  408         brelse(bp);
  409         bp = 0;
  410         
  411 foundroot:
  412         /*
  413          * If we entered at foundroot, then we are looking for the . or ..
  414          * entry of the filesystems root directory.  isadir and scn were
  415          * setup before jumping here.  And, bp is already null.
  416          */
  417         if (FAT32(pmp) && scn == MSDOSFSROOT)
  418                 scn = pmp->pm_rootdirblk;
  419 
  420         /*
  421          * If deleting, and at end of pathname, return
  422          * parameters which can be used to remove file.
  423          * If the wantparent flag isn't set, we return only
  424          * the directory (in ndp->ni_dvp), otherwise we go
  425          * on and lock the inode, being careful with ".".
  426          */
  427         if (nameiop == DELETE && (flags & ISLASTCN)) {
  428                 /*
  429                  * Don't allow deleting the root.
  430                  */
  431                 if (blkoff == MSDOSFSROOT_OFS)
  432                         return EROFS;                           /* really? XXX */
  433 
  434                 /*
  435                  * Write access to directory required to delete files.
  436                  */
  437                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_proc);
  438                 if (error)
  439                         return (error);
  440 
  441                 /*
  442                  * Return pointer to current entry in dp->i_offset.
  443                  * Save directory inode pointer in ndp->ni_dvp for dirremove().
  444                  */
  445                 if (dp->de_StartCluster == scn && isadir) {     /* "." */
  446                         VREF(vdp);
  447                         *vpp = vdp;
  448                         return (0);
  449                 }
  450                 error = deget(pmp, cluster, blkoff, &tdp);
  451                 if (error)
  452                         return (error);
  453                 *vpp = DETOV(tdp);
  454                 if (!lockparent)
  455                         VOP_UNLOCK(vdp, 0, p);
  456                 return (0);
  457         }
  458 
  459         /*
  460          * If rewriting (RENAME), return the inode and the
  461          * information required to rewrite the present directory
  462          * Must get inode of directory entry to verify it's a
  463          * regular file, or empty directory.
  464          */
  465         if (nameiop == RENAME && wantparent &&
  466             (flags & ISLASTCN)) {
  467                 if (blkoff == MSDOSFSROOT_OFS)
  468                         return EROFS;                           /* really? XXX */
  469 
  470                 error = VOP_ACCESS(vdp, VWRITE, cnp->cn_cred, cnp->cn_proc);
  471                 if (error)
  472                         return (error);
  473 
  474                 /*
  475                  * Careful about locking second inode.
  476                  * This can only occur if the target is ".".
  477                  */
  478                 if (dp->de_StartCluster == scn && isadir)
  479                         return (EISDIR);
  480 
  481                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  482                         return (error);
  483                 *vpp = DETOV(tdp);
  484                 cnp->cn_flags |= SAVENAME;
  485                 if (!lockparent)
  486                         VOP_UNLOCK(vdp, 0, p);
  487                 return (0);
  488         }
  489 
  490         /*
  491          * Step through the translation in the name.  We do not `vput' the
  492          * directory because we may need it again if a symbolic link
  493          * is relative to the current directory.  Instead we save it
  494          * unlocked as "pdp".  We must get the target inode before unlocking
  495          * the directory to insure that the inode will not be removed
  496          * before we get it.  We prevent deadlock by always fetching
  497          * inodes from the root, moving down the directory tree. Thus
  498          * when following backward pointers ".." we must unlock the
  499          * parent directory before getting the requested directory.
  500          * There is a potential race condition here if both the current
  501          * and parent directories are removed before the VFS_VGET for the
  502          * inode associated with ".." returns.  We hope that this occurs
  503          * infrequently since we cannot avoid this race condition without
  504          * implementing a sophisticated deadlock detection algorithm.
  505          * Note also that this simple deadlock detection scheme will not
  506          * work if the file system has any hard links other than ".."
  507          * that point backwards in the directory structure.
  508          */
  509         pdp = vdp;
  510         if (flags & ISDOTDOT) {
  511                 VOP_UNLOCK(pdp, 0, p);
  512                 error = deget(pmp, cluster, blkoff,  &tdp);
  513                 if (error) {
  514                         vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY, p); 
  515                         return (error);
  516                 }
  517                 if (lockparent && (flags & ISLASTCN) &&
  518                     (error = vn_lock(pdp, LK_EXCLUSIVE, p))) {
  519                         vput(DETOV(tdp));
  520                         return (error);
  521                 }
  522                 *vpp = DETOV(tdp);
  523         } else if (dp->de_StartCluster == scn && isadir) {
  524                 VREF(vdp);      /* we want ourself, ie "." */
  525                 *vpp = vdp;
  526         } else {
  527                 if ((error = deget(pmp, cluster, blkoff, &tdp)) != 0)
  528                         return (error);
  529                 if (!lockparent || !(flags & ISLASTCN))
  530                         VOP_UNLOCK(pdp, 0, p);
  531                 *vpp = DETOV(tdp);
  532         }
  533 
  534         /*
  535          * Insert name into cache if appropriate.
  536          */
  537         if (cnp->cn_flags & MAKEENTRY)
  538                 cache_enter(vdp, *vpp, cnp);
  539         return (0);
  540 }
  541 
  542 /*
  543  * dep  - directory entry to copy into the directory
  544  * ddep - directory to add to
  545  * depp - return the address of the denode for the created directory entry
  546  *        if depp != 0
  547  * cnp  - componentname needed for Win95 long filenames
  548  */
  549 int
  550 createde(dep, ddep, depp, cnp)
  551         struct denode *dep;
  552         struct denode *ddep;
  553         struct denode **depp;
  554         struct componentname *cnp;
  555 {
  556         int error;
  557         u_long dirclust, diroffset;
  558         struct direntry *ndep;
  559         struct msdosfsmount *pmp = ddep->de_pmp;
  560         struct buf *bp;
  561         daddr_t bn;
  562         int blsize;
  563 
  564 #ifdef MSDOSFS_DEBUG
  565         printf("createde(dep %p, ddep %p, depp %p, cnp %p)\n",
  566             dep, ddep, depp, cnp);
  567 #endif
  568 
  569         /*
  570          * If no space left in the directory then allocate another cluster
  571          * and chain it onto the end of the file.  There is one exception
  572          * to this.  That is, if the root directory has no more space it
  573          * can NOT be expanded.  extendfile() checks for and fails attempts
  574          * to extend the root directory.  We just return an error in that
  575          * case.
  576          */
  577         if (ddep->de_fndoffset >= ddep->de_FileSize) {
  578                 diroffset = ddep->de_fndoffset + sizeof(struct direntry)
  579                     - ddep->de_FileSize;
  580                 dirclust = de_clcount(pmp, diroffset);
  581                 error = extendfile(ddep, dirclust, 0, 0, DE_CLEAR);
  582                 if (error) {
  583                         (void)detrunc(ddep, ddep->de_FileSize, 0, NOCRED, NULL);
  584                         return error;
  585                 }
  586 
  587                 /*
  588                  * Update the size of the directory
  589                  */
  590                 ddep->de_FileSize += de_cn2off(pmp, dirclust);
  591         }
  592 
  593         /*
  594          * We just read in the cluster with space.  Copy the new directory
  595          * entry in.  Then write it to disk. NOTE:  DOS directories
  596          * do not get smaller as clusters are emptied.
  597          */
  598         error = pcbmap(ddep, de_cluster(pmp, ddep->de_fndoffset),
  599                        &bn, &dirclust, &blsize);
  600         if (error)
  601                 return error;
  602         diroffset = ddep->de_fndoffset;
  603         if (dirclust != MSDOSFSROOT)
  604                 diroffset &= pmp->pm_crbomask;
  605         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) != 0) {
  606                 brelse(bp);
  607                 return error;
  608         }
  609         ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  610 
  611         DE_EXTERNALIZE(ndep, dep);
  612 
  613         /*
  614          * Now write the Win95 long name
  615          */
  616         if (ddep->de_fndcnt > 0) {
  617                 u_int8_t chksum = winChksum(ndep->deName);
  618                 const u_char *un = (const u_char *)cnp->cn_nameptr;
  619                 int unlen = cnp->cn_namelen;
  620                 int cnt = 1;
  621 
  622                 while (--ddep->de_fndcnt >= 0) {
  623                         if (!(ddep->de_fndoffset & pmp->pm_crbomask)) {
  624                                 if ((error = bwrite(bp)) != 0)
  625                                         return error;
  626 
  627                                 ddep->de_fndoffset -= sizeof(struct direntry);
  628                                 error = pcbmap(ddep,
  629                                                de_cluster(pmp,
  630                                                           ddep->de_fndoffset),
  631                                                &bn, 0, &blsize);
  632                                 if (error)
  633                                         return error;
  634 
  635                                 error = bread(pmp->pm_devvp, bn, blsize,
  636                                               NOCRED, &bp);
  637                                 if (error) {
  638                                         brelse(bp);
  639                                         return error;
  640                                 }
  641                                 ndep = bptoep(pmp, bp, ddep->de_fndoffset);
  642                         } else {
  643                                 ndep--;
  644                                 ddep->de_fndoffset -= sizeof(struct direntry);
  645                         }
  646                         if (!unix2winfn(un, unlen, (struct winentry *)ndep,
  647                                         cnt++, chksum,
  648                                         pmp->pm_flags & MSDOSFSMNT_U2WTABLE,
  649                                         pmp->pm_u2w))
  650                                 break;
  651                 }
  652         }
  653 
  654         if ((error = bwrite(bp)) != 0)
  655                 return error;
  656 
  657         /*
  658          * If they want us to return with the denode gotten.
  659          */
  660         if (depp) {
  661                 if (dep->de_Attributes & ATTR_DIRECTORY) {
  662                         dirclust = dep->de_StartCluster;
  663                         if (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)
  664                                 dirclust = MSDOSFSROOT;
  665                         if (dirclust == MSDOSFSROOT)
  666                                 diroffset = MSDOSFSROOT_OFS;
  667                         else
  668                                 diroffset = 0;
  669                 }
  670                 return deget(pmp, dirclust, diroffset, depp);
  671         }
  672 
  673         return 0;
  674 }
  675 
  676 /*
  677  * Be sure a directory is empty except for "." and "..". Return 1 if empty,
  678  * return 0 if not empty or error.
  679  */
  680 int
  681 dosdirempty(dep)
  682         struct denode *dep;
  683 {
  684         int blsize;
  685         int error;
  686         u_long cn;
  687         daddr_t bn;
  688         struct buf *bp;
  689         struct msdosfsmount *pmp = dep->de_pmp;
  690         struct direntry *dentp;
  691 
  692         /*
  693          * Since the filesize field in directory entries for a directory is
  694          * zero, we just have to feel our way through the directory until
  695          * we hit end of file.
  696          */
  697         for (cn = 0;; cn++) {
  698                 if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
  699                         if (error == E2BIG)
  700                                 return (1);     /* it's empty */
  701                         return (0);
  702                 }
  703                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  704                 if (error) {
  705                         brelse(bp);
  706                         return (0);
  707                 }
  708                 for (dentp = (struct direntry *)bp->b_data;
  709                      (char *)dentp < bp->b_data + blsize;
  710                      dentp++) {
  711                         if (dentp->deName[0] != SLOT_DELETED &&
  712                             (dentp->deAttributes & ATTR_VOLUME) == 0) {
  713                                 /*
  714                                  * In dos directories an entry whose name
  715                                  * starts with SLOT_EMPTY (0) starts the
  716                                  * beginning of the unused part of the
  717                                  * directory, so we can just return that it
  718                                  * is empty.
  719                                  */
  720                                 if (dentp->deName[0] == SLOT_EMPTY) {
  721                                         brelse(bp);
  722                                         return (1);
  723                                 }
  724                                 /*
  725                                  * Any names other than "." and ".." in a
  726                                  * directory mean it is not empty.
  727                                  */
  728                                 if (bcmp(dentp->deName, ".          ", 11) &&
  729                                     bcmp(dentp->deName, "..         ", 11)) {
  730                                         brelse(bp);
  731 #ifdef MSDOSFS_DEBUG
  732                                         printf("dosdirempty(): entry found %02x, %02x\n",
  733                                             dentp->deName[0], dentp->deName[1]);
  734 #endif
  735                                         return (0);     /* not empty */
  736                                 }
  737                         }
  738                 }
  739                 brelse(bp);
  740         }
  741         /* NOTREACHED */
  742 }
  743 
  744 /*
  745  * Check to see if the directory described by target is in some
  746  * subdirectory of source.  This prevents something like the following from
  747  * succeeding and leaving a bunch or files and directories orphaned. mv
  748  * /a/b/c /a/b/c/d/e/f Where c and f are directories.
  749  *
  750  * source - the inode for /a/b/c
  751  * target - the inode for /a/b/c/d/e/f
  752  *
  753  * Returns 0 if target is NOT a subdirectory of source.
  754  * Otherwise returns a non-zero error number.
  755  * The target inode is always unlocked on return.
  756  */
  757 int
  758 doscheckpath(source, target)
  759         struct denode *source;
  760         struct denode *target;
  761 {
  762         daddr_t scn;
  763         struct msdosfsmount *pmp;
  764         struct direntry *ep;
  765         struct denode *dep;
  766         struct buf *bp = NULL;
  767         int error = 0;
  768 
  769         dep = target;
  770         if ((target->de_Attributes & ATTR_DIRECTORY) == 0 ||
  771             (source->de_Attributes & ATTR_DIRECTORY) == 0) {
  772                 error = ENOTDIR;
  773                 goto out;
  774         }
  775         if (dep->de_StartCluster == source->de_StartCluster) {
  776                 error = EEXIST;
  777                 goto out;
  778         }
  779         if (dep->de_StartCluster == MSDOSFSROOT)
  780                 goto out;
  781         pmp = dep->de_pmp;
  782 #ifdef  DIAGNOSTIC
  783         if (pmp != source->de_pmp)
  784                 panic("doscheckpath: source and target on different filesystems");
  785 #endif
  786         if (FAT32(pmp) && dep->de_StartCluster == pmp->pm_rootdirblk)
  787                 goto out;
  788 
  789         for (;;) {
  790                 if ((dep->de_Attributes & ATTR_DIRECTORY) == 0) {
  791                         error = ENOTDIR;
  792                         break;
  793                 }
  794                 scn = dep->de_StartCluster;
  795                 error = bread(pmp->pm_devvp, cntobn(pmp, scn),
  796                               pmp->pm_bpcluster, NOCRED, &bp);
  797                 if (error)
  798                         break;
  799 
  800                 ep = (struct direntry *) bp->b_data + 1;
  801                 if ((ep->deAttributes & ATTR_DIRECTORY) == 0 ||
  802                     bcmp(ep->deName, "..         ", 11) != 0) {
  803                         error = ENOTDIR;
  804                         break;
  805                 }
  806                 scn = getushort(ep->deStartCluster);
  807                 if (FAT32(pmp))
  808                         scn |= getushort(ep->deHighClust) << 16;
  809 
  810                 if (scn == source->de_StartCluster) {
  811                         error = EINVAL;
  812                         break;
  813                 }
  814                 if (scn == MSDOSFSROOT)
  815                         break;
  816                 if (FAT32(pmp) && scn == pmp->pm_rootdirblk) {
  817                         /*
  818                          * scn should be 0 in this case,
  819                          * but we silently ignore the error.
  820                          */
  821                         break;
  822                 }
  823 
  824                 vput(DETOV(dep));
  825                 brelse(bp);
  826                 bp = NULL;
  827                 /* NOTE: deget() clears dep on error */
  828                 if ((error = deget(pmp, scn, 0, &dep)) != 0)
  829                         break;
  830         }
  831 out:;
  832         if (bp)
  833                 brelse(bp);
  834         if (error == ENOTDIR)
  835                 printf("doscheckpath(): .. not a directory?\n");
  836         if (dep != NULL)
  837                 vput(DETOV(dep));
  838         return (error);
  839 }
  840 
  841 /*
  842  * Read in the disk block containing the directory entry (dirclu, dirofs)
  843  * and return the address of the buf header, and the address of the
  844  * directory entry within the block.
  845  */
  846 int
  847 readep(pmp, dirclust, diroffset, bpp, epp)
  848         struct msdosfsmount *pmp;
  849         u_long dirclust, diroffset;
  850         struct buf **bpp;
  851         struct direntry **epp;
  852 {
  853         int error;
  854         daddr_t bn;
  855         int blsize;
  856 
  857         blsize = pmp->pm_bpcluster;
  858         if (dirclust == MSDOSFSROOT
  859             && de_blk(pmp, diroffset + blsize) > pmp->pm_rootdirsize)
  860                 blsize = de_bn2off(pmp, pmp->pm_rootdirsize) & pmp->pm_crbomask;
  861         bn = detobn(pmp, dirclust, diroffset);
  862         if ((error = bread(pmp->pm_devvp, bn, blsize, NOCRED, bpp)) != 0) {
  863                 brelse(*bpp);
  864                 *bpp = NULL;
  865                 return (error);
  866         }
  867         if (epp)
  868                 *epp = bptoep(pmp, *bpp, diroffset);
  869         return (0);
  870 }
  871 
  872 /*
  873  * Read in the disk block containing the directory entry dep came from and
  874  * return the address of the buf header, and the address of the directory
  875  * entry within the block.
  876  */
  877 int
  878 readde(dep, bpp, epp)
  879         struct denode *dep;
  880         struct buf **bpp;
  881         struct direntry **epp;
  882 {
  883 
  884         return (readep(dep->de_pmp, dep->de_dirclust, dep->de_diroffset,
  885             bpp, epp));
  886 }
  887 
  888 /*
  889  * Remove a directory entry. At this point the file represented by the
  890  * directory entry to be removed is still full length until noone has it
  891  * open.  When the file no longer being used msdosfs_inactive() is called
  892  * and will truncate the file to 0 length.  When the vnode containing the
  893  * denode is needed for some other purpose by VFS it will call
  894  * msdosfs_reclaim() which will remove the denode from the denode cache.
  895  */
  896 int
  897 removede(pdep, dep)
  898         struct denode *pdep;    /* directory where the entry is removed */
  899         struct denode *dep;     /* file to be removed */
  900 {
  901         int error;
  902         struct direntry *ep;
  903         struct buf *bp;
  904         daddr_t bn;
  905         int blsize;
  906         struct msdosfsmount *pmp = pdep->de_pmp;
  907         u_long offset = pdep->de_fndoffset;
  908 
  909 #ifdef MSDOSFS_DEBUG
  910         printf("removede(): filename %s, dep %p, offset %08lx\n",
  911             dep->de_Name, dep, offset);
  912 #endif
  913 
  914         dep->de_refcnt--;
  915         offset += sizeof(struct direntry);
  916         do {
  917                 offset -= sizeof(struct direntry);
  918                 error = pcbmap(pdep, de_cluster(pmp, offset), &bn, 0, &blsize);
  919                 if (error)
  920                         return error;
  921                 error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
  922                 if (error) {
  923                         brelse(bp);
  924                         return error;
  925                 }
  926                 ep = bptoep(pmp, bp, offset);
  927                 /*
  928                  * Check whether, if we came here the second time, i.e.
  929                  * when underflowing into the previous block, the last
  930                  * entry in this block is a longfilename entry, too.
  931                  */
  932                 if (ep->deAttributes != ATTR_WIN95
  933                     && offset != pdep->de_fndoffset) {
  934                         brelse(bp);
  935                         break;
  936                 }
  937                 offset += sizeof(struct direntry);
  938                 while (1) {
  939                         /*
  940                          * We are a bit agressive here in that we delete any Win95
  941                          * entries preceding this entry, not just the ones we "own".
  942                          * Since these presumably aren't valid anyway,
  943                          * there should be no harm.
  944                          */
  945                         offset -= sizeof(struct direntry);
  946                         ep--->deName[0] = SLOT_DELETED;
  947                         if ((pmp->pm_flags & MSDOSFSMNT_NOWIN95)
  948                             || !(offset & pmp->pm_crbomask)
  949                             || ep->deAttributes != ATTR_WIN95)
  950                                 break;
  951                 }
  952                 if ((error = bwrite(bp)) != 0)
  953                         return error;
  954         } while (!(pmp->pm_flags & MSDOSFSMNT_NOWIN95)
  955             && !(offset & pmp->pm_crbomask)
  956             && offset);
  957         return 0;
  958 }
  959 
  960 /*
  961  * Create a unique DOS name in dvp
  962  */
  963 int
  964 uniqdosname(dep, cnp, cp)
  965         struct denode *dep;
  966         struct componentname *cnp;
  967         u_char *cp;
  968 {
  969         struct msdosfsmount *pmp = dep->de_pmp;
  970         struct direntry *dentp;
  971         int gen;
  972         int blsize;
  973         u_long cn;
  974         daddr_t bn;
  975         struct buf *bp;
  976         int error;
  977         
  978         if (pmp->pm_flags & MSDOSFSMNT_SHORTNAME)
  979                 return (unix2dosfn((const u_char *)cnp->cn_nameptr, cp,
  980                     cnp->cn_namelen, 0,
  981                     pmp->pm_flags & MSDOSFSMNT_U2WTABLE, pmp->pm_u2d,
  982                     pmp->pm_flags & MSDOSFSMNT_ULTABLE, pmp->pm_lu) ?
  983                     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,
  991                     pmp->pm_flags & MSDOSFSMNT_U2WTABLE, pmp->pm_u2d,
  992                     pmp->pm_flags & MSDOSFSMNT_ULTABLE, pmp->pm_lu))
  993                         return gen == 1 ? EINVAL : EEXIST;
  994 
  995                 /*
  996                  * Now look for a dir entry with this exact name
  997                  */
  998                 for (cn = error = 0; !error; cn++) {
  999                         if ((error = pcbmap(dep, cn, &bn, 0, &blsize)) != 0) {
 1000                                 if (error == E2BIG)     /* EOF reached and not found */
 1001                                         return 0;
 1002                                 return error;
 1003                         }
 1004                         error = bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp);
 1005                         if (error) {
 1006                                 brelse(bp);
 1007                                 return error;
 1008                         }
 1009                         for (dentp = (struct direntry *)bp->b_data;
 1010                              (char *)dentp < bp->b_data + blsize;
 1011                              dentp++) {
 1012                                 if (dentp->deName[0] == SLOT_EMPTY) {
 1013                                         /*
 1014                                          * Last used entry and not found
 1015                                          */
 1016                                         brelse(bp);
 1017                                         return 0;
 1018                                 }
 1019                                 /*
 1020                                  * Ignore volume labels and Win95 entries
 1021                                  */
 1022                                 if (dentp->deAttributes & ATTR_VOLUME)
 1023                                         continue;
 1024                                 if (!bcmp(dentp->deName, cp, 11)) {
 1025                                         error = EEXIST;
 1026                                         break;
 1027                                 }
 1028                         }
 1029                         brelse(bp);
 1030                 }
 1031         }
 1032 }
 1033 
 1034 /*
 1035  * Find any Win'95 long filename entry in directory dep
 1036  */
 1037 int
 1038 findwin95(dep)
 1039         struct denode *dep;
 1040 {
 1041         struct msdosfsmount *pmp = dep->de_pmp;
 1042         struct direntry *dentp;
 1043         int blsize, win95;
 1044         u_long cn;
 1045         daddr_t bn;
 1046         struct buf *bp;
 1047 
 1048         win95 = 1;
 1049         /*
 1050          * Read through the directory looking for Win'95 entries
 1051          * Note: Error currently handled just as EOF                    XXX
 1052          */
 1053         for (cn = 0;; cn++) {
 1054                 if (pcbmap(dep, cn, &bn, 0, &blsize))
 1055                         return (win95);
 1056                 if (bread(pmp->pm_devvp, bn, blsize, NOCRED, &bp)) {
 1057                         brelse(bp);
 1058                         return (win95);
 1059                 }
 1060                 for (dentp = (struct direntry *)bp->b_data;
 1061                      (char *)dentp < bp->b_data + blsize;
 1062                      dentp++) {
 1063                         if (dentp->deName[0] == SLOT_EMPTY) {
 1064                                 /*
 1065                                  * Last used entry and not found
 1066                                  */
 1067                                 brelse(bp);
 1068                                 return (win95);
 1069                         }
 1070                         if (dentp->deName[0] == SLOT_DELETED) {
 1071                                 /*
 1072                                  * Ignore deleted files
 1073                                  * Note: might be an indication of Win'95 anyway        XXX
 1074                                  */
 1075                                 continue;
 1076                         }
 1077                         if (dentp->deAttributes == ATTR_WIN95) {
 1078                                 brelse(bp);
 1079                                 return 1;
 1080                         }
 1081                         win95 = 0;
 1082                 }
 1083                 brelse(bp);
 1084         }
 1085 }

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