The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/ext2fs/ext2_lookup.c

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    1 /*-
    2  *  modified for Lites 1.1
    3  *
    4  *  Aug 1995, Godmar Back (gback@cs.utah.edu)
    5  *  University of Utah, Department of Computer Science
    6  */
    7 /*-
    8  * Copyright (c) 1989, 1993
    9  *      The Regents of the University of California.  All rights reserved.
   10  * (c) UNIX System Laboratories, Inc.
   11  * All or some portions of this file are derived from material licensed
   12  * to the University of California by American Telephone and Telegraph
   13  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   14  * the permission of UNIX System Laboratories, Inc.
   15  *
   16  * Redistribution and use in source and binary forms, with or without
   17  * modification, are permitted provided that the following conditions
   18  * are met:
   19  * 1. Redistributions of source code must retain the above copyright
   20  *    notice, this list of conditions and the following disclaimer.
   21  * 2. Redistributions in binary form must reproduce the above copyright
   22  *    notice, this list of conditions and the following disclaimer in the
   23  *    documentation and/or other materials provided with the distribution.
   24  * 4. Neither the name of the University nor the names of its contributors
   25  *    may be used to endorse or promote products derived from this software
   26  *    without specific prior written permission.
   27  *
   28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   38  * SUCH DAMAGE.
   39  *
   40  *      @(#)ufs_lookup.c        8.6 (Berkeley) 4/1/94
   41  * $FreeBSD: releng/9.2/sys/fs/ext2fs/ext2_lookup.c 252677 2013-07-04 01:40:32Z pfg $
   42  */
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/namei.h>
   47 #include <sys/bio.h>
   48 #include <sys/buf.h>
   49 #include <sys/endian.h>
   50 #include <sys/mount.h>
   51 #include <sys/vnode.h>
   52 #include <sys/malloc.h>
   53 #include <sys/dirent.h>
   54 #include <sys/sysctl.h>
   55 
   56 #include <ufs/ufs/dir.h>
   57 
   58 #include <fs/ext2fs/inode.h>
   59 #include <fs/ext2fs/ext2_mount.h>
   60 #include <fs/ext2fs/ext2fs.h>
   61 #include <fs/ext2fs/ext2_dinode.h>
   62 #include <fs/ext2fs/ext2_dir.h>
   63 #include <fs/ext2fs/ext2_extern.h>
   64 
   65 #ifdef INVARIANTS
   66 static int dirchk = 1;
   67 #else
   68 static int dirchk = 0;
   69 #endif
   70 
   71 static SYSCTL_NODE(_vfs, OID_AUTO, e2fs, CTLFLAG_RD, 0, "EXT2FS filesystem");
   72 SYSCTL_INT(_vfs_e2fs, OID_AUTO, dircheck, CTLFLAG_RW, &dirchk, 0, "");
   73 
   74 /*
   75    DIRBLKSIZE in ffs is DEV_BSIZE (in most cases 512)
   76    while it is the native blocksize in ext2fs - thus, a #define
   77    is no longer appropriate
   78 */
   79 #undef  DIRBLKSIZ
   80 
   81 static u_char ext2_ft_to_dt[] = {
   82         DT_UNKNOWN,             /* EXT2_FT_UNKNOWN */
   83         DT_REG,                 /* EXT2_FT_REG_FILE */
   84         DT_DIR,                 /* EXT2_FT_DIR */
   85         DT_CHR,                 /* EXT2_FT_CHRDEV */
   86         DT_BLK,                 /* EXT2_FT_BLKDEV */
   87         DT_FIFO,                /* EXT2_FT_FIFO */
   88         DT_SOCK,                /* EXT2_FT_SOCK */
   89         DT_LNK,                 /* EXT2_FT_SYMLINK */
   90 };
   91 #define FTTODT(ft) \
   92     ((ft) < nitems(ext2_ft_to_dt) ? ext2_ft_to_dt[(ft)] : DT_UNKNOWN)
   93 
   94 static u_char dt_to_ext2_ft[] = {
   95         EXT2_FT_UNKNOWN,        /* DT_UNKNOWN */
   96         EXT2_FT_FIFO,           /* DT_FIFO */
   97         EXT2_FT_CHRDEV,         /* DT_CHR */
   98         EXT2_FT_UNKNOWN,        /* unused */
   99         EXT2_FT_DIR,            /* DT_DIR */
  100         EXT2_FT_UNKNOWN,        /* unused */
  101         EXT2_FT_BLKDEV,         /* DT_BLK */
  102         EXT2_FT_UNKNOWN,        /* unused */
  103         EXT2_FT_REG_FILE,       /* DT_REG */
  104         EXT2_FT_UNKNOWN,        /* unused */
  105         EXT2_FT_SYMLINK,        /* DT_LNK */
  106         EXT2_FT_UNKNOWN,        /* unused */
  107         EXT2_FT_SOCK,           /* DT_SOCK */
  108         EXT2_FT_UNKNOWN,        /* unused */
  109         EXT2_FT_UNKNOWN,        /* DT_WHT */
  110 };
  111 #define DTTOFT(dt) \
  112     ((dt) < nitems(dt_to_ext2_ft) ? dt_to_ext2_ft[(dt)] : EXT2_FT_UNKNOWN)
  113 
  114 static int      ext2_dirbadentry(struct vnode *dp, struct ext2fs_direct_2 *de,
  115                     int entryoffsetinblock);
  116 static int      ext2_lookup_ino(struct vnode *vdp, struct vnode **vpp,
  117                     struct componentname *cnp, ino_t *dd_ino);
  118 
  119 /*
  120  * Vnode op for reading directories.
  121  *
  122  * This function has to convert directory entries from the on-disk
  123  * format to the format defined by <sys/dirent.h>.  Unfortunately, the
  124  * conversion will blow up some entries by four bytes, so it can't be
  125  * done in place.  Instead, the conversion is done entry by entry and
  126  * the converted entry is sent via uiomove.
  127  *
  128  * XXX allocate a buffer, convert as many entries as possible, then send
  129  * the whole buffer to uiomove
  130  */
  131 int
  132 ext2_readdir(struct vop_readdir_args *ap)
  133 {
  134         struct uio *uio = ap->a_uio;
  135         int count, error;
  136 
  137         struct ext2fs_direct_2 *edp, *dp;
  138         int ncookies;
  139         struct dirent dstdp;
  140         struct uio auio;
  141         struct iovec aiov;
  142         caddr_t dirbuf;
  143         int DIRBLKSIZ = VTOI(ap->a_vp)->i_e2fs->e2fs_bsize;
  144         int readcnt;
  145         off_t startoffset = uio->uio_offset;
  146 
  147         count = uio->uio_resid;
  148         /*
  149          * Avoid complications for partial directory entries by adjusting
  150          * the i/o to end at a block boundary.  Don't give up (like ufs
  151          * does) if the initial adjustment gives a negative count, since
  152          * many callers don't supply a large enough buffer.  The correct
  153          * size is a little larger than DIRBLKSIZ to allow for expansion
  154          * of directory entries, but some callers just use 512.
  155          */
  156         count -= (uio->uio_offset + count) & (DIRBLKSIZ -1);
  157         if (count <= 0)
  158                 count += DIRBLKSIZ;
  159         auio = *uio;
  160         auio.uio_iov = &aiov;
  161         auio.uio_iovcnt = 1;
  162         auio.uio_resid = count;
  163         auio.uio_segflg = UIO_SYSSPACE;
  164         aiov.iov_len = count;
  165         dirbuf = malloc(count, M_TEMP, M_WAITOK);
  166         aiov.iov_base = dirbuf;
  167         error = VOP_READ(ap->a_vp, &auio, 0, ap->a_cred);
  168         if (error == 0) {
  169                 readcnt = count - auio.uio_resid;
  170                 edp = (struct ext2fs_direct_2 *)&dirbuf[readcnt];
  171                 ncookies = 0;
  172                 bzero(&dstdp, offsetof(struct dirent, d_name));
  173                 for (dp = (struct ext2fs_direct_2 *)dirbuf;
  174                     !error && uio->uio_resid > 0 && dp < edp; ) {
  175                         /*-
  176                          * "New" ext2fs directory entries differ in 3 ways
  177                          * from ufs on-disk ones:
  178                          * - the name is not necessarily NUL-terminated.
  179                          * - the file type field always exists and always
  180                          *   follows the name length field.
  181                          * - the file type is encoded in a different way.
  182                          *
  183                          * "Old" ext2fs directory entries need no special
  184                          * conversions, since they are binary compatible
  185                          * with "new" entries having a file type of 0 (i.e.,
  186                          * EXT2_FT_UNKNOWN).  Splitting the old name length
  187                          * field didn't make a mess like it did in ufs,
  188                          * because ext2fs uses a machine-independent disk
  189                          * layout.
  190                          */
  191                         dstdp.d_fileno = dp->e2d_ino;
  192                         dstdp.d_type = FTTODT(dp->e2d_type);
  193                         dstdp.d_namlen = dp->e2d_namlen;
  194                         dstdp.d_reclen = GENERIC_DIRSIZ(&dstdp);
  195                         bcopy(dp->e2d_name, dstdp.d_name, dstdp.d_namlen);
  196                         bzero(dstdp.d_name + dstdp.d_namlen,
  197                             dstdp.d_reclen - offsetof(struct dirent, d_name) -
  198                             dstdp.d_namlen);
  199 
  200                         if (dp->e2d_reclen > 0) {
  201                                 if(dstdp.d_reclen <= uio->uio_resid) {
  202                                         /* advance dp */
  203                                         dp = (struct ext2fs_direct_2 *)
  204                                             ((char *)dp + dp->e2d_reclen);
  205                                         error =
  206                                           uiomove(&dstdp, dstdp.d_reclen, uio);
  207                                         if (!error)
  208                                                 ncookies++;
  209                                 } else
  210                                         break;
  211                         } else {
  212                                 error = EIO;
  213                                 break;
  214                         }
  215                 }
  216                 /* we need to correct uio_offset */
  217                 uio->uio_offset = startoffset + (caddr_t)dp - dirbuf;
  218 
  219                 if (!error && ap->a_ncookies != NULL) {
  220                         u_long *cookiep, *cookies, *ecookies;
  221                         off_t off;
  222 
  223                         if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1)
  224                                 panic("ext2_readdir: unexpected uio from NFS server");
  225                         cookies = malloc(ncookies * sizeof(u_long), M_TEMP,
  226                                M_WAITOK);
  227                         off = startoffset;
  228                         for (dp = (struct ext2fs_direct_2 *)dirbuf,
  229                              cookiep = cookies, ecookies = cookies + ncookies;
  230                              cookiep < ecookies;
  231                              dp = (struct ext2fs_direct_2 *)((caddr_t) dp + dp->e2d_reclen)) {
  232                                 off += dp->e2d_reclen;
  233                                 *cookiep++ = (u_long) off;
  234                         }
  235                         *ap->a_ncookies = ncookies;
  236                         *ap->a_cookies = cookies;
  237                 }
  238         }
  239         free(dirbuf, M_TEMP);
  240         if (ap->a_eofflag)
  241                 *ap->a_eofflag = VTOI(ap->a_vp)->i_size <= uio->uio_offset;
  242         return (error);
  243 }
  244 
  245 /*
  246  * Convert a component of a pathname into a pointer to a locked inode.
  247  * This is a very central and rather complicated routine.
  248  * If the file system is not maintained in a strict tree hierarchy,
  249  * this can result in a deadlock situation (see comments in code below).
  250  *
  251  * The cnp->cn_nameiop argument is LOOKUP, CREATE, RENAME, or DELETE depending
  252  * on whether the name is to be looked up, created, renamed, or deleted.
  253  * When CREATE, RENAME, or DELETE is specified, information usable in
  254  * creating, renaming, or deleting a directory entry may be calculated.
  255  * If flag has LOCKPARENT or'ed into it and the target of the pathname
  256  * exists, lookup returns both the target and its parent directory locked.
  257  * When creating or renaming and LOCKPARENT is specified, the target may
  258  * not be ".".  When deleting and LOCKPARENT is specified, the target may
  259  * be "."., but the caller must check to ensure it does an vrele and vput
  260  * instead of two vputs.
  261  *
  262  * Overall outline of ext2_lookup:
  263  *
  264  *      search for name in directory, to found or notfound
  265  * notfound:
  266  *      if creating, return locked directory, leaving info on available slots
  267  *      else return error
  268  * found:
  269  *      if at end of path and deleting, return information to allow delete
  270  *      if at end of path and rewriting (RENAME and LOCKPARENT), lock target
  271  *        inode and return info to allow rewrite
  272  *      if not at end, add name to cache; if at end and neither creating
  273  *        nor deleting, add name to cache
  274  */
  275 int
  276 ext2_lookup(struct vop_cachedlookup_args *ap)
  277 {
  278 
  279         return (ext2_lookup_ino(ap->a_dvp, ap->a_vpp, ap->a_cnp, NULL));
  280 }
  281 
  282 static int
  283 ext2_lookup_ino(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
  284     ino_t *dd_ino)
  285 {
  286         struct inode *dp;               /* inode for directory being searched */
  287         struct buf *bp;                 /* a buffer of directory entries */
  288         struct ext2fs_direct_2 *ep;     /* the current directory entry */
  289         int entryoffsetinblock;         /* offset of ep in bp's buffer */
  290         enum {NONE, COMPACT, FOUND} slotstatus;
  291         doff_t slotoffset;              /* offset of area with free space */
  292         doff_t i_diroff;                /* cached i_diroff value */
  293         doff_t i_offset;                /* cached i_offset value */
  294         int slotsize;                   /* size of area at slotoffset */
  295         int slotfreespace;              /* amount of space free in slot */
  296         int slotneeded;                 /* size of the entry we're seeking */
  297         int numdirpasses;               /* strategy for directory search */
  298         doff_t endsearch;               /* offset to end directory search */
  299         doff_t prevoff;                 /* prev entry dp->i_offset */
  300         struct vnode *pdp;              /* saved dp during symlink work */
  301         struct vnode *tdp;              /* returned by VFS_VGET */
  302         doff_t enduseful;               /* pointer past last used dir slot */
  303         u_long bmask;                   /* block offset mask */
  304         int namlen, error;
  305         struct ucred *cred = cnp->cn_cred;
  306         int flags = cnp->cn_flags;
  307         int nameiop = cnp->cn_nameiop;
  308         ino_t ino, ino1;
  309         int ltype;
  310 
  311         int     DIRBLKSIZ = VTOI(vdp)->i_e2fs->e2fs_bsize;
  312 
  313         if (vpp != NULL)
  314                 *vpp = NULL;
  315 
  316         dp = VTOI(vdp);
  317         bmask = VFSTOEXT2(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
  318 restart:
  319         bp = NULL;
  320         slotoffset = -1;
  321 
  322         /*
  323          * We now have a segment name to search for, and a directory to search.
  324          */
  325 
  326         /*
  327          * Suppress search for slots unless creating
  328          * file and at end of pathname, in which case
  329          * we watch for a place to put the new file in
  330          * case it doesn't already exist.
  331          */
  332         ino = 0;
  333         i_diroff = dp->i_diroff;
  334         slotstatus = FOUND;
  335         slotfreespace = slotsize = slotneeded = 0;
  336         if ((nameiop == CREATE || nameiop == RENAME) &&
  337             (flags & ISLASTCN)) {
  338                 slotstatus = NONE;
  339                 slotneeded = EXT2_DIR_REC_LEN(cnp->cn_namelen);
  340                 /* was
  341                 slotneeded = (sizeof(struct direct) - MAXNAMLEN +
  342                         cnp->cn_namelen + 3) &~ 3; */
  343         }
  344 
  345         /*
  346          * If there is cached information on a previous search of
  347          * this directory, pick up where we last left off.
  348          * We cache only lookups as these are the most common
  349          * and have the greatest payoff. Caching CREATE has little
  350          * benefit as it usually must search the entire directory
  351          * to determine that the entry does not exist. Caching the
  352          * location of the last DELETE or RENAME has not reduced
  353          * profiling time and hence has been removed in the interest
  354          * of simplicity.
  355          */
  356         if (nameiop != LOOKUP || i_diroff == 0 ||
  357             i_diroff > dp->i_size) {
  358                 entryoffsetinblock = 0;
  359                 i_offset = 0;
  360                 numdirpasses = 1;
  361         } else {
  362                 i_offset = i_diroff;
  363                 if ((entryoffsetinblock = i_offset & bmask) &&
  364                     (error = ext2_blkatoff(vdp, (off_t)i_offset, NULL,
  365                     &bp)))
  366                         return (error);
  367                 numdirpasses = 2;
  368                 nchstats.ncs_2passes++;
  369         }
  370         prevoff = i_offset;
  371         endsearch = roundup2(dp->i_size, DIRBLKSIZ);
  372         enduseful = 0;
  373 
  374 searchloop:
  375         while (i_offset < endsearch) {
  376                 /*
  377                  * If necessary, get the next directory block.
  378                  */
  379                 if ((i_offset & bmask) == 0) {
  380                         if (bp != NULL)
  381                                 brelse(bp);
  382                         if ((error =
  383                             ext2_blkatoff(vdp, (off_t)i_offset, NULL,
  384                             &bp)) != 0)
  385                                 return (error);
  386                         entryoffsetinblock = 0;
  387                 }
  388                 /*
  389                  * If still looking for a slot, and at a DIRBLKSIZE
  390                  * boundary, have to start looking for free space again.
  391                  */
  392                 if (slotstatus == NONE &&
  393                     (entryoffsetinblock & (DIRBLKSIZ - 1)) == 0) {
  394                         slotoffset = -1;
  395                         slotfreespace = 0;
  396                 }
  397                 /*
  398                  * Get pointer to next entry.
  399                  * Full validation checks are slow, so we only check
  400                  * enough to insure forward progress through the
  401                  * directory. Complete checks can be run by setting
  402                  * "vfs.e2fs.dirchk" to be true.
  403                  */
  404                 ep = (struct ext2fs_direct_2 *)
  405                         ((char *)bp->b_data + entryoffsetinblock);
  406                 if (ep->e2d_reclen == 0 ||
  407                     (dirchk && ext2_dirbadentry(vdp, ep, entryoffsetinblock))) {
  408                         int i;
  409                         ext2_dirbad(dp, i_offset, "mangled entry");
  410                         i = DIRBLKSIZ - (entryoffsetinblock & (DIRBLKSIZ - 1));
  411                         i_offset += i;
  412                         entryoffsetinblock += i;
  413                         continue;
  414                 }
  415 
  416                 /*
  417                  * If an appropriate sized slot has not yet been found,
  418                  * check to see if one is available. Also accumulate space
  419                  * in the current block so that we can determine if
  420                  * compaction is viable.
  421                  */
  422                 if (slotstatus != FOUND) {
  423                         int size = ep->e2d_reclen;
  424 
  425                         if (ep->e2d_ino != 0)
  426                                 size -= EXT2_DIR_REC_LEN(ep->e2d_namlen);
  427                         if (size > 0) {
  428                                 if (size >= slotneeded) {
  429                                         slotstatus = FOUND;
  430                                         slotoffset = i_offset;
  431                                         slotsize = ep->e2d_reclen;
  432                                 } else if (slotstatus == NONE) {
  433                                         slotfreespace += size;
  434                                         if (slotoffset == -1)
  435                                                 slotoffset = i_offset;
  436                                         if (slotfreespace >= slotneeded) {
  437                                                 slotstatus = COMPACT;
  438                                                 slotsize = i_offset +
  439                                                       ep->e2d_reclen - slotoffset;
  440                                         }
  441                                 }
  442                         }
  443                 }
  444 
  445                 /*
  446                  * Check for a name match.
  447                  */
  448                 if (ep->e2d_ino) {
  449                         namlen = ep->e2d_namlen;
  450                         if (namlen == cnp->cn_namelen &&
  451                             !bcmp(cnp->cn_nameptr, ep->e2d_name,
  452                                 (unsigned)namlen)) {
  453                                 /*
  454                                  * Save directory entry's inode number and
  455                                  * reclen in ndp->ni_ufs area, and release
  456                                  * directory buffer.
  457                                  */
  458                                 ino = ep->e2d_ino;
  459                                 goto found;
  460                         }
  461                 }
  462                 prevoff = i_offset;
  463                 i_offset += ep->e2d_reclen;
  464                 entryoffsetinblock += ep->e2d_reclen;
  465                 if (ep->e2d_ino)
  466                         enduseful = i_offset;
  467         }
  468 /* notfound: */
  469         /*
  470          * If we started in the middle of the directory and failed
  471          * to find our target, we must check the beginning as well.
  472          */
  473         if (numdirpasses == 2) {
  474                 numdirpasses--;
  475                 i_offset = 0;
  476                 endsearch = i_diroff;
  477                 goto searchloop;
  478         }
  479         if (bp != NULL)
  480                 brelse(bp);
  481         /*
  482          * If creating, and at end of pathname and current
  483          * directory has not been removed, then can consider
  484          * allowing file to be created.
  485          */
  486         if ((nameiop == CREATE || nameiop == RENAME) &&
  487             (flags & ISLASTCN) && dp->i_nlink != 0) {
  488                 /*
  489                  * Access for write is interpreted as allowing
  490                  * creation of files in the directory.
  491                  */
  492                 if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
  493                         return (error);
  494                 /*
  495                  * Return an indication of where the new directory
  496                  * entry should be put.  If we didn't find a slot,
  497                  * then set dp->i_count to 0 indicating
  498                  * that the new slot belongs at the end of the
  499                  * directory. If we found a slot, then the new entry
  500                  * can be put in the range from dp->i_offset to
  501                  * dp->i_offset + dp->i_count.
  502                  */
  503                 if (slotstatus == NONE) {
  504                         dp->i_offset = roundup2(dp->i_size, DIRBLKSIZ);
  505                         dp->i_count = 0;
  506                         enduseful = dp->i_offset;
  507                 } else {
  508                         dp->i_offset = slotoffset;
  509                         dp->i_count = slotsize;
  510                         if (enduseful < slotoffset + slotsize)
  511                                 enduseful = slotoffset + slotsize;
  512                 }
  513                 dp->i_endoff = roundup2(enduseful, DIRBLKSIZ);
  514                 /*
  515                  * We return with the directory locked, so that
  516                  * the parameters we set up above will still be
  517                  * valid if we actually decide to do a direnter().
  518                  * We return ni_vp == NULL to indicate that the entry
  519                  * does not currently exist; we leave a pointer to
  520                  * the (locked) directory inode in ndp->ni_dvp.
  521                  * The pathname buffer is saved so that the name
  522                  * can be obtained later.
  523                  *
  524                  * NB - if the directory is unlocked, then this
  525                  * information cannot be used.
  526                  */
  527                 cnp->cn_flags |= SAVENAME;
  528                 return (EJUSTRETURN);
  529         }
  530         /*
  531          * Insert name into cache (as non-existent) if appropriate.
  532          */
  533         if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
  534                 cache_enter(vdp, NULL, cnp);
  535         return (ENOENT);
  536 
  537 found:
  538         if (dd_ino != NULL)
  539                 *dd_ino = ino;
  540         if (numdirpasses == 2)
  541                 nchstats.ncs_pass2++;
  542         /*
  543          * Check that directory length properly reflects presence
  544          * of this entry.
  545          */
  546         if (entryoffsetinblock + EXT2_DIR_REC_LEN(ep->e2d_namlen)
  547                 > dp->i_size) {
  548                 ext2_dirbad(dp, i_offset, "i_size too small");
  549                 dp->i_size = entryoffsetinblock+EXT2_DIR_REC_LEN(ep->e2d_namlen);
  550                 dp->i_flag |= IN_CHANGE | IN_UPDATE;
  551         }
  552         brelse(bp);
  553 
  554         /*
  555          * Found component in pathname.
  556          * If the final component of path name, save information
  557          * in the cache as to where the entry was found.
  558          */
  559         if ((flags & ISLASTCN) && nameiop == LOOKUP)
  560                 dp->i_diroff = i_offset &~ (DIRBLKSIZ - 1);
  561         /*
  562          * If deleting, and at end of pathname, return
  563          * parameters which can be used to remove file.
  564          */
  565         if (nameiop == DELETE && (flags & ISLASTCN)) {
  566                 if (flags & LOCKPARENT)
  567                         ASSERT_VOP_ELOCKED(vdp, __FUNCTION__);
  568                 /*
  569                  * Write access to directory required to delete files.
  570                  */
  571                 if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
  572                         return (error);
  573                 /*
  574                  * Return pointer to current entry in dp->i_offset,
  575                  * and distance past previous entry (if there
  576                  * is a previous entry in this block) in dp->i_count.
  577                  * Save directory inode pointer in ndp->ni_dvp for dirremove().
  578                  *
  579                  * Technically we shouldn't be setting these in the
  580                  * WANTPARENT case (first lookup in rename()), but any
  581                  * lookups that will result in directory changes will
  582                  * overwrite these.
  583                  */
  584                 dp->i_offset = i_offset;
  585                 if ((dp->i_offset & (DIRBLKSIZ - 1)) == 0)
  586                         dp->i_count = 0;
  587                 else
  588                         dp->i_count = dp->i_offset - prevoff;
  589                 if (dd_ino != NULL)
  590                         return (0);
  591                 if (dp->i_number == ino) {
  592                         VREF(vdp);
  593                         *vpp = vdp;
  594                         return (0);
  595                 }
  596                 if ((error = VFS_VGET(vdp->v_mount, ino, LK_EXCLUSIVE,
  597                     &tdp)) != 0)
  598                         return (error);
  599                 /*
  600                  * If directory is "sticky", then user must own
  601                  * the directory, or the file in it, else she
  602                  * may not delete it (unless she's root). This
  603                  * implements append-only directories.
  604                  */
  605                 if ((dp->i_mode & ISVTX) &&
  606                     cred->cr_uid != 0 &&
  607                     cred->cr_uid != dp->i_uid &&
  608                     VTOI(tdp)->i_uid != cred->cr_uid) {
  609                         vput(tdp);
  610                         return (EPERM);
  611                 }
  612                 *vpp = tdp;
  613                 return (0);
  614         }
  615 
  616         /*
  617          * If rewriting (RENAME), return the inode and the
  618          * information required to rewrite the present directory
  619          * Must get inode of directory entry to verify it's a
  620          * regular file, or empty directory.
  621          */
  622         if (nameiop == RENAME && (flags & ISLASTCN)) {
  623                 if ((error = VOP_ACCESS(vdp, VWRITE, cred, cnp->cn_thread)) != 0)
  624                         return (error);
  625                 /*
  626                  * Careful about locking second inode.
  627                  * This can only occur if the target is ".".
  628                  */
  629                 dp->i_offset = i_offset;
  630                 if (dp->i_number == ino)
  631                         return (EISDIR);
  632                 if (dd_ino != NULL)
  633                         return (0);
  634                 if ((error = VFS_VGET(vdp->v_mount, ino, LK_EXCLUSIVE,
  635                     &tdp)) != 0)
  636                         return (error);
  637                 *vpp = tdp;
  638                 cnp->cn_flags |= SAVENAME;
  639                 return (0);
  640         }
  641         if (dd_ino != NULL)
  642                 return (0);
  643 
  644         /*
  645          * Step through the translation in the name.  We do not `vput' the
  646          * directory because we may need it again if a symbolic link
  647          * is relative to the current directory.  Instead we save it
  648          * unlocked as "pdp".  We must get the target inode before unlocking
  649          * the directory to insure that the inode will not be removed
  650          * before we get it.  We prevent deadlock by always fetching
  651          * inodes from the root, moving down the directory tree. Thus
  652          * when following backward pointers ".." we must unlock the
  653          * parent directory before getting the requested directory.
  654          * There is a potential race condition here if both the current
  655          * and parent directories are removed before the VFS_VGET for the
  656          * inode associated with ".." returns.  We hope that this occurs
  657          * infrequently since we cannot avoid this race condition without
  658          * implementing a sophisticated deadlock detection algorithm.
  659          * Note also that this simple deadlock detection scheme will not
  660          * work if the file system has any hard links other than ".."
  661          * that point backwards in the directory structure.
  662          */
  663         pdp = vdp;
  664         if (flags & ISDOTDOT) {
  665                 error = vn_vget_ino(pdp, ino, cnp->cn_lkflags, &tdp);
  666                 if (pdp->v_iflag & VI_DOOMED) {
  667                         if (error == 0)
  668                                 vput(tdp);
  669                         error = ENOENT;
  670                 }
  671                 if (error)
  672                         return (error);
  673                 /*
  674                  * Recheck that ".." entry in the vdp directory points
  675                  * to the inode we looked up before vdp lock was
  676                  * dropped.
  677                  */
  678                 error = ext2_lookup_ino(pdp, NULL, cnp, &ino1);
  679                 if (error) {
  680                         vput(tdp);
  681                         return (error);
  682                 }
  683                 if (ino1 != ino) {
  684                         vput(tdp);
  685                         goto restart;
  686                 }
  687                 *vpp = tdp;
  688         } else if (dp->i_number == ino) {
  689                 VREF(vdp);      /* we want ourself, ie "." */
  690                 /*
  691                  * When we lookup "." we still can be asked to lock it
  692                  * differently.
  693                  */
  694                 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
  695                 if (ltype != VOP_ISLOCKED(vdp)) {
  696                         if (ltype == LK_EXCLUSIVE)
  697                                 vn_lock(vdp, LK_UPGRADE | LK_RETRY);
  698                         else /* if (ltype == LK_SHARED) */
  699                                 vn_lock(vdp, LK_DOWNGRADE | LK_RETRY);
  700                 }
  701                 *vpp = vdp;
  702         } else {
  703                 if ((error = VFS_VGET(vdp->v_mount, ino, cnp->cn_lkflags,
  704                     &tdp)) != 0)
  705                         return (error);
  706                 *vpp = tdp;
  707         }
  708 
  709         /*
  710          * Insert name into cache if appropriate.
  711          */
  712         if (cnp->cn_flags & MAKEENTRY)
  713                 cache_enter(vdp, *vpp, cnp);
  714         return (0);
  715 }
  716 
  717 void
  718 ext2_dirbad(struct inode *ip, doff_t offset, char *how)
  719 {
  720         struct mount *mp;
  721 
  722         mp = ITOV(ip)->v_mount;
  723         if ((mp->mnt_flag & MNT_RDONLY) == 0)
  724                 panic("ext2_dirbad: %s: bad dir ino %lu at offset %ld: %s\n",
  725                         mp->mnt_stat.f_mntonname, (u_long)ip->i_number,(long)offset, how);
  726         else
  727         (void)printf("%s: bad dir ino %lu at offset %ld: %s\n",
  728             mp->mnt_stat.f_mntonname, (u_long)ip->i_number, (long)offset, how);
  729 
  730 }
  731 
  732 /*
  733  * Do consistency checking on a directory entry:
  734  *      record length must be multiple of 4
  735  *      entry must fit in rest of its DIRBLKSIZ block
  736  *      record must be large enough to contain entry
  737  *      name is not longer than MAXNAMLEN
  738  *      name must be as long as advertised, and null terminated
  739  */
  740 /*
  741  *      changed so that it confirms to ext2_check_dir_entry
  742  */
  743 static int
  744 ext2_dirbadentry(struct vnode *dp, struct ext2fs_direct_2 *de,
  745     int entryoffsetinblock)
  746 {
  747         int     DIRBLKSIZ = VTOI(dp)->i_e2fs->e2fs_bsize;
  748 
  749         char * error_msg = NULL;
  750 
  751         if (de->e2d_reclen < EXT2_DIR_REC_LEN(1))
  752                 error_msg = "rec_len is smaller than minimal";
  753         else if (de->e2d_reclen % 4 != 0)
  754                 error_msg = "rec_len % 4 != 0";
  755         else if (de->e2d_reclen < EXT2_DIR_REC_LEN(de->e2d_namlen))
  756                 error_msg = "reclen is too small for name_len";
  757         else if (entryoffsetinblock + de->e2d_reclen > DIRBLKSIZ)
  758                 error_msg = "directory entry across blocks";
  759         /* else LATER
  760              if (de->inode > dir->i_sb->u.ext2_sb.s_es->s_inodes_count)
  761                 error_msg = "inode out of bounds";
  762         */
  763 
  764         if (error_msg != NULL) {
  765                 printf("bad directory entry: %s\n", error_msg);
  766                 printf("offset=%d, inode=%lu, rec_len=%u, name_len=%u\n",
  767                         entryoffsetinblock, (unsigned long)de->e2d_ino,
  768                         de->e2d_reclen, de->e2d_namlen);
  769         }
  770         return error_msg == NULL ? 0 : 1;
  771 }
  772 
  773 /*
  774  * Write a directory entry after a call to namei, using the parameters
  775  * that it left in nameidata.  The argument ip is the inode which the new
  776  * directory entry will refer to.  Dvp is a pointer to the directory to
  777  * be written, which was left locked by namei. Remaining parameters
  778  * (dp->i_offset, dp->i_count) indicate how the space for the new
  779  * entry is to be obtained.
  780  */
  781 int
  782 ext2_direnter(struct inode *ip, struct vnode *dvp, struct componentname *cnp)
  783 {
  784         struct ext2fs_direct_2 *ep, *nep;
  785         struct inode *dp;
  786         struct buf *bp;
  787         struct ext2fs_direct_2 newdir;
  788         struct iovec aiov;
  789         struct uio auio;
  790         u_int dsize;
  791         int error, loc, newentrysize, spacefree;
  792         char *dirbuf;
  793         int     DIRBLKSIZ = ip->i_e2fs->e2fs_bsize;
  794 
  795 
  796 #ifdef INVARIANTS
  797         if ((cnp->cn_flags & SAVENAME) == 0)
  798                 panic("ext2_direnter: missing name");
  799 #endif
  800         dp = VTOI(dvp);
  801         newdir.e2d_ino = ip->i_number;
  802         newdir.e2d_namlen = cnp->cn_namelen;
  803         if (EXT2_HAS_INCOMPAT_FEATURE(ip->i_e2fs,
  804             EXT2F_INCOMPAT_FTYPE))
  805                 newdir.e2d_type = DTTOFT(IFTODT(ip->i_mode));
  806         else
  807                 newdir.e2d_type = EXT2_FT_UNKNOWN;
  808         bcopy(cnp->cn_nameptr, newdir.e2d_name, (unsigned)cnp->cn_namelen + 1);
  809         newentrysize = EXT2_DIR_REC_LEN(newdir.e2d_namlen);
  810         if (dp->i_count == 0) {
  811                 /*
  812                  * If dp->i_count is 0, then namei could find no
  813                  * space in the directory. Here, dp->i_offset will
  814                  * be on a directory block boundary and we will write the
  815                  * new entry into a fresh block.
  816                  */
  817                 if (dp->i_offset & (DIRBLKSIZ - 1))
  818                         panic("ext2_direnter: newblk");
  819                 auio.uio_offset = dp->i_offset;
  820                 newdir.e2d_reclen = DIRBLKSIZ;
  821                 auio.uio_resid = newentrysize;
  822                 aiov.iov_len = newentrysize;
  823                 aiov.iov_base = (caddr_t)&newdir;
  824                 auio.uio_iov = &aiov;
  825                 auio.uio_iovcnt = 1;
  826                 auio.uio_rw = UIO_WRITE;
  827                 auio.uio_segflg = UIO_SYSSPACE;
  828                 auio.uio_td = (struct thread *)0;
  829                 error = VOP_WRITE(dvp, &auio, IO_SYNC, cnp->cn_cred);
  830                 if (DIRBLKSIZ >
  831                     VFSTOEXT2(dvp->v_mount)->um_mountp->mnt_stat.f_bsize)
  832                         /* XXX should grow with balloc() */
  833                         panic("ext2_direnter: frag size");
  834                 else if (!error) {
  835                         dp->i_size = roundup2(dp->i_size, DIRBLKSIZ);
  836                         dp->i_flag |= IN_CHANGE;
  837                 }
  838                 return (error);
  839         }
  840 
  841         /*
  842          * If dp->i_count is non-zero, then namei found space
  843          * for the new entry in the range dp->i_offset to
  844          * dp->i_offset + dp->i_count in the directory.
  845          * To use this space, we may have to compact the entries located
  846          * there, by copying them together towards the beginning of the
  847          * block, leaving the free space in one usable chunk at the end.
  848          */
  849 
  850         /*
  851          * Increase size of directory if entry eats into new space.
  852          * This should never push the size past a new multiple of
  853          * DIRBLKSIZE.
  854          *
  855          * N.B. - THIS IS AN ARTIFACT OF 4.2 AND SHOULD NEVER HAPPEN.
  856          */
  857         if (dp->i_offset + dp->i_count > dp->i_size)
  858                 dp->i_size = dp->i_offset + dp->i_count;
  859         /*
  860          * Get the block containing the space for the new directory entry.
  861          */
  862         if ((error = ext2_blkatoff(dvp, (off_t)dp->i_offset, &dirbuf,
  863             &bp)) != 0)
  864                 return (error);
  865         /*
  866          * Find space for the new entry. In the simple case, the entry at
  867          * offset base will have the space. If it does not, then namei
  868          * arranged that compacting the region dp->i_offset to
  869          * dp->i_offset + dp->i_count would yield the
  870          * space.
  871          */
  872         ep = (struct ext2fs_direct_2 *)dirbuf;
  873         dsize = EXT2_DIR_REC_LEN(ep->e2d_namlen);
  874         spacefree = ep->e2d_reclen - dsize;
  875         for (loc = ep->e2d_reclen; loc < dp->i_count; ) {
  876                 nep = (struct ext2fs_direct_2 *)(dirbuf + loc);
  877                 if (ep->e2d_ino) {
  878                         /* trim the existing slot */
  879                         ep->e2d_reclen = dsize;
  880                         ep = (struct ext2fs_direct_2 *)((char *)ep + dsize);
  881                 } else {
  882                         /* overwrite; nothing there; header is ours */
  883                         spacefree += dsize;
  884                 }
  885                 dsize = EXT2_DIR_REC_LEN(nep->e2d_namlen);
  886                 spacefree += nep->e2d_reclen - dsize;
  887                 loc += nep->e2d_reclen;
  888                 bcopy((caddr_t)nep, (caddr_t)ep, dsize);
  889         }
  890         /*
  891          * Update the pointer fields in the previous entry (if any),
  892          * copy in the new entry, and write out the block.
  893          */
  894         if (ep->e2d_ino == 0) {
  895                 if (spacefree + dsize < newentrysize)
  896                         panic("ext2_direnter: compact1");
  897                 newdir.e2d_reclen = spacefree + dsize;
  898         } else {
  899                 if (spacefree < newentrysize)
  900                         panic("ext2_direnter: compact2");
  901                 newdir.e2d_reclen = spacefree;
  902                 ep->e2d_reclen = dsize;
  903                 ep = (struct ext2fs_direct_2 *)((char *)ep + dsize);
  904         }
  905         bcopy((caddr_t)&newdir, (caddr_t)ep, (u_int)newentrysize);
  906         if (DOINGASYNC(dvp)) {
  907                 bdwrite(bp);
  908                 error = 0;
  909         } else {
  910                 error = bwrite(bp);
  911         }
  912         dp->i_flag |= IN_CHANGE | IN_UPDATE;
  913         if (!error && dp->i_endoff && dp->i_endoff < dp->i_size)
  914                 error = ext2_truncate(dvp, (off_t)dp->i_endoff, IO_SYNC,
  915                     cnp->cn_cred, cnp->cn_thread);
  916         return (error);
  917 }
  918 
  919 /*
  920  * Remove a directory entry after a call to namei, using
  921  * the parameters which it left in nameidata. The entry
  922  * dp->i_offset contains the offset into the directory of the
  923  * entry to be eliminated.  The dp->i_count field contains the
  924  * size of the previous record in the directory.  If this
  925  * is 0, the first entry is being deleted, so we need only
  926  * zero the inode number to mark the entry as free.  If the
  927  * entry is not the first in the directory, we must reclaim
  928  * the space of the now empty record by adding the record size
  929  * to the size of the previous entry.
  930  */
  931 int
  932 ext2_dirremove(struct vnode *dvp, struct componentname *cnp)
  933 {
  934         struct inode *dp;
  935         struct ext2fs_direct_2 *ep, *rep;
  936         struct buf *bp;
  937         int error;
  938 
  939         dp = VTOI(dvp);
  940         if (dp->i_count == 0) {
  941                 /*
  942                  * First entry in block: set d_ino to zero.
  943                  */
  944                 if ((error =
  945                     ext2_blkatoff(dvp, (off_t)dp->i_offset, (char **)&ep,
  946                     &bp)) != 0)
  947                         return (error);
  948                 ep->e2d_ino = 0;
  949                 error = bwrite(bp);
  950                 dp->i_flag |= IN_CHANGE | IN_UPDATE;
  951                 return (error);
  952         }
  953         /*
  954          * Collapse new free space into previous entry.
  955          */
  956         if ((error = ext2_blkatoff(dvp, (off_t)(dp->i_offset - dp->i_count),
  957             (char **)&ep, &bp)) != 0)
  958                 return (error);
  959 
  960         /* Set 'rep' to the entry being removed. */
  961         if (dp->i_count == 0)
  962                 rep = ep;
  963         else
  964                 rep = (struct ext2fs_direct_2 *)((char *)ep + ep->e2d_reclen);
  965         ep->e2d_reclen += rep->e2d_reclen;
  966         if (DOINGASYNC(dvp) && dp->i_count != 0)
  967                 bdwrite(bp);
  968         else
  969                 error = bwrite(bp);
  970         dp->i_flag |= IN_CHANGE | IN_UPDATE;
  971         return (error);
  972 }
  973 
  974 /*
  975  * Rewrite an existing directory entry to point at the inode
  976  * supplied.  The parameters describing the directory entry are
  977  * set up by a call to namei.
  978  */
  979 int
  980 ext2_dirrewrite(struct inode *dp, struct inode *ip, struct componentname *cnp)
  981 {
  982         struct buf *bp;
  983         struct ext2fs_direct_2 *ep;
  984         struct vnode *vdp = ITOV(dp);
  985         int error;
  986 
  987         if ((error = ext2_blkatoff(vdp, (off_t)dp->i_offset, (char **)&ep,
  988             &bp)) != 0)
  989                 return (error);
  990         ep->e2d_ino = ip->i_number;
  991         if (EXT2_HAS_INCOMPAT_FEATURE(ip->i_e2fs,
  992             EXT2F_INCOMPAT_FTYPE))
  993                 ep->e2d_type = DTTOFT(IFTODT(ip->i_mode));
  994         else
  995                 ep->e2d_type = EXT2_FT_UNKNOWN;
  996         error = bwrite(bp);
  997         dp->i_flag |= IN_CHANGE | IN_UPDATE;
  998         return (error);
  999 }
 1000 
 1001 /*
 1002  * Check if a directory is empty or not.
 1003  * Inode supplied must be locked.
 1004  *
 1005  * Using a struct dirtemplate here is not precisely
 1006  * what we want, but better than using a struct direct.
 1007  *
 1008  * NB: does not handle corrupted directories.
 1009  */
 1010 int
 1011 ext2_dirempty(struct inode *ip, ino_t parentino, struct ucred *cred)
 1012 {
 1013         off_t off;
 1014         struct dirtemplate dbuf;
 1015         struct ext2fs_direct_2 *dp = (struct ext2fs_direct_2 *)&dbuf;
 1016         int error, namlen;
 1017         ssize_t count;
 1018 #define MINDIRSIZ (sizeof(struct dirtemplate) / 2)
 1019 
 1020         for (off = 0; off < ip->i_size; off += dp->e2d_reclen) {
 1021                 error = vn_rdwr(UIO_READ, ITOV(ip), (caddr_t)dp, MINDIRSIZ,
 1022                     off, UIO_SYSSPACE, IO_NODELOCKED | IO_NOMACCHECK, cred,
 1023                     NOCRED, &count, (struct thread *)0);
 1024                 /*
 1025                  * Since we read MINDIRSIZ, residual must
 1026                  * be 0 unless we're at end of file.
 1027                  */
 1028                 if (error || count != 0)
 1029                         return (0);
 1030                 /* avoid infinite loops */
 1031                 if (dp->e2d_reclen == 0)
 1032                         return (0);
 1033                 /* skip empty entries */
 1034                 if (dp->e2d_ino == 0)
 1035                         continue;
 1036                 /* accept only "." and ".." */
 1037                 namlen = dp->e2d_namlen;
 1038                 if (namlen > 2)
 1039                         return (0);
 1040                 if (dp->e2d_name[0] != '.')
 1041                         return (0);
 1042                 /*
 1043                  * At this point namlen must be 1 or 2.
 1044                  * 1 implies ".", 2 implies ".." if second
 1045                  * char is also "."
 1046                  */
 1047                 if (namlen == 1)
 1048                         continue;
 1049                 if (dp->e2d_name[1] == '.' && dp->e2d_ino == parentino)
 1050                         continue;
 1051                 return (0);
 1052         }
 1053         return (1);
 1054 }
 1055 
 1056 /*
 1057  * Check if source directory is in the path of the target directory.
 1058  * Target is supplied locked, source is unlocked.
 1059  * The target is always vput before returning.
 1060  */
 1061 int
 1062 ext2_checkpath(struct inode *source, struct inode *target, struct ucred *cred)
 1063 {
 1064         struct vnode *vp;
 1065         int error, namlen;
 1066         struct dirtemplate dirbuf;
 1067 
 1068         vp = ITOV(target);
 1069         if (target->i_number == source->i_number) {
 1070                 error = EEXIST;
 1071                 goto out;
 1072         }
 1073         if (target->i_number == EXT2_ROOTINO) {
 1074                 error = 0;
 1075                 goto out;
 1076         }
 1077 
 1078         for (;;) {
 1079                 if (vp->v_type != VDIR) {
 1080                         error = ENOTDIR;
 1081                         break;
 1082                 }
 1083                 error = vn_rdwr(UIO_READ, vp, (caddr_t)&dirbuf,
 1084                         sizeof(struct dirtemplate), (off_t)0, UIO_SYSSPACE,
 1085                         IO_NODELOCKED | IO_NOMACCHECK, cred, NOCRED, NULL,
 1086                         NULL);
 1087                 if (error != 0)
 1088                         break;
 1089                 namlen = dirbuf.dotdot_type;    /* like ufs little-endian */
 1090                 if (namlen != 2 ||
 1091                     dirbuf.dotdot_name[0] != '.' ||
 1092                     dirbuf.dotdot_name[1] != '.') {
 1093                         error = ENOTDIR;
 1094                         break;
 1095                 }
 1096                 if (dirbuf.dotdot_ino == source->i_number) {
 1097                         error = EINVAL;
 1098                         break;
 1099                 }
 1100                 if (dirbuf.dotdot_ino == EXT2_ROOTINO)
 1101                         break;
 1102                 vput(vp);
 1103                 if ((error = VFS_VGET(vp->v_mount, dirbuf.dotdot_ino,
 1104                     LK_EXCLUSIVE, &vp)) != 0) {
 1105                         vp = NULL;
 1106                         break;
 1107                 }
 1108         }
 1109 
 1110 out:
 1111         if (error == ENOTDIR)
 1112                 printf("checkpath: .. not a directory\n");
 1113         if (vp != NULL)
 1114                 vput(vp);
 1115         return (error);
 1116 }

Cache object: e891e2c6e25918de753c12f3b967e62f


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