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

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1992, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * This code is derived from software donated to Berkeley by
    8  * Jan-Simon Pendry.
    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. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)fdesc_vnops.c       8.9 (Berkeley) 1/21/94
   35  *
   36  * $FreeBSD$
   37  */
   38 
   39 /*
   40  * /dev/fd Filesystem
   41  */
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/capsicum.h>
   46 #include <sys/conf.h>
   47 #include <sys/dirent.h>
   48 #include <sys/filedesc.h>
   49 #include <sys/kernel.h> /* boottime */
   50 #include <sys/lock.h>
   51 #include <sys/mutex.h>
   52 #include <sys/malloc.h>
   53 #include <sys/file.h>   /* Must come after sys/malloc.h */
   54 #include <sys/mount.h>
   55 #include <sys/namei.h>
   56 #include <sys/proc.h>
   57 #include <sys/stat.h>
   58 #include <sys/syscallsubr.h>
   59 #include <sys/unistd.h>
   60 #include <sys/vnode.h>
   61 
   62 #include <fs/fdescfs/fdesc.h>
   63 
   64 #define NFDCACHE 4
   65 #define FD_NHASH(ix) \
   66         (&fdhashtbl[(ix) & fdhash])
   67 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl;
   68 static u_long fdhash;
   69 
   70 struct mtx fdesc_hashmtx;
   71 
   72 static vop_getattr_t    fdesc_getattr;
   73 static vop_lookup_t     fdesc_lookup;
   74 static vop_open_t       fdesc_open;
   75 static vop_pathconf_t   fdesc_pathconf;
   76 static vop_readdir_t    fdesc_readdir;
   77 static vop_readlink_t   fdesc_readlink;
   78 static vop_reclaim_t    fdesc_reclaim;
   79 static vop_setattr_t    fdesc_setattr;
   80 
   81 static struct vop_vector fdesc_vnodeops = {
   82         .vop_default =          &default_vnodeops,
   83 
   84         .vop_access =           VOP_NULL,
   85         .vop_getattr =          fdesc_getattr,
   86         .vop_lookup =           fdesc_lookup,
   87         .vop_open =             fdesc_open,
   88         .vop_pathconf =         fdesc_pathconf,
   89         .vop_readdir =          fdesc_readdir,
   90         .vop_readlink =         fdesc_readlink,
   91         .vop_reclaim =          fdesc_reclaim,
   92         .vop_setattr =          fdesc_setattr,
   93 };
   94 VFS_VOP_VECTOR_REGISTER(fdesc_vnodeops);
   95 
   96 static void fdesc_remove_entry(struct fdescnode *);
   97 
   98 /*
   99  * Initialise cache headers
  100  */
  101 int
  102 fdesc_init(struct vfsconf *vfsp)
  103 {
  104 
  105         mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF);
  106         fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash);
  107         return (0);
  108 }
  109 
  110 /*
  111  * Uninit ready for unload.
  112  */
  113 int
  114 fdesc_uninit(struct vfsconf *vfsp)
  115 {
  116 
  117         hashdestroy(fdhashtbl, M_CACHE, fdhash);
  118         mtx_destroy(&fdesc_hashmtx);
  119         return (0);
  120 }
  121 
  122 /*
  123  * Remove an entry from the hash if it exists.
  124  */
  125 static void
  126 fdesc_remove_entry(struct fdescnode *fd)
  127 {
  128         struct fdhashhead *fc;
  129         struct fdescnode *fd2;
  130 
  131         fc = FD_NHASH(fd->fd_ix);
  132         mtx_lock(&fdesc_hashmtx);
  133         LIST_FOREACH(fd2, fc, fd_hash) {
  134                 if (fd == fd2) {
  135                         LIST_REMOVE(fd, fd_hash);
  136                         break;
  137                 }
  138         }
  139         mtx_unlock(&fdesc_hashmtx);
  140 }
  141 
  142 int
  143 fdesc_allocvp(fdntype ftype, unsigned fd_fd, int ix, struct mount *mp,
  144     struct vnode **vpp)
  145 {
  146         struct fdescmount *fmp;
  147         struct fdhashhead *fc;
  148         struct fdescnode *fd, *fd2;
  149         struct vnode *vp, *vp2;
  150         int error;
  151 
  152         fc = FD_NHASH(ix);
  153 loop:
  154         mtx_lock(&fdesc_hashmtx);
  155         /*
  156          * If a forced unmount is progressing, we need to drop it. The flags are
  157          * protected by the hashmtx.
  158          */
  159         fmp = mp->mnt_data;
  160         if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
  161                 mtx_unlock(&fdesc_hashmtx);
  162                 return (-1);
  163         }
  164 
  165         LIST_FOREACH(fd, fc, fd_hash) {
  166                 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
  167                         /* Get reference to vnode in case it's being free'd */
  168                         vp = fd->fd_vnode;
  169                         VI_LOCK(vp);
  170                         mtx_unlock(&fdesc_hashmtx);
  171                         if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK))
  172                                 goto loop;
  173                         *vpp = vp;
  174                         return (0);
  175                 }
  176         }
  177         mtx_unlock(&fdesc_hashmtx);
  178 
  179         fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK);
  180 
  181         error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp);
  182         if (error) {
  183                 free(fd, M_TEMP);
  184                 return (error);
  185         }
  186         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  187         vp->v_data = fd;
  188         fd->fd_vnode = vp;
  189         fd->fd_type = ftype;
  190         fd->fd_fd = fd_fd;
  191         fd->fd_ix = ix;
  192         if (ftype == Fdesc && fmp->flags & FMNT_LINRDLNKF)
  193                 vp->v_vflag |= VV_READLINK;
  194         error = insmntque1(vp, mp);
  195         if (error != 0) {
  196                 vgone(vp);
  197                 vput(vp);
  198                 *vpp = NULLVP;
  199                 return (error);
  200         }
  201 
  202         /* Make sure that someone didn't beat us when inserting the vnode. */
  203         mtx_lock(&fdesc_hashmtx);
  204         /*
  205          * If a forced unmount is progressing, we need to drop it. The flags are
  206          * protected by the hashmtx.
  207          */
  208         fmp = mp->mnt_data;
  209         if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
  210                 mtx_unlock(&fdesc_hashmtx);
  211                 vgone(vp);
  212                 vput(vp);
  213                 *vpp = NULLVP;
  214                 return (-1);
  215         }
  216 
  217         LIST_FOREACH(fd2, fc, fd_hash) {
  218                 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) {
  219                         /* Get reference to vnode in case it's being free'd */
  220                         vp2 = fd2->fd_vnode;
  221                         VI_LOCK(vp2);
  222                         mtx_unlock(&fdesc_hashmtx);
  223                         error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK);
  224                         /* Someone beat us, dec use count and wait for reclaim */
  225                         vgone(vp);
  226                         vput(vp);
  227                         /* If we didn't get it, return no vnode. */
  228                         if (error)
  229                                 vp2 = NULLVP;
  230                         *vpp = vp2;
  231                         return (error);
  232                 }
  233         }
  234 
  235         /* If we came here, we can insert it safely. */
  236         LIST_INSERT_HEAD(fc, fd, fd_hash);
  237         mtx_unlock(&fdesc_hashmtx);
  238         vn_set_state(vp, VSTATE_CONSTRUCTED);
  239         *vpp = vp;
  240         return (0);
  241 }
  242 
  243 struct fdesc_get_ino_args {
  244         fdntype ftype;
  245         unsigned fd_fd;
  246         int ix;
  247         struct file *fp;
  248         struct thread *td;
  249 };
  250 
  251 static int
  252 fdesc_get_ino_alloc(struct mount *mp, void *arg, int lkflags,
  253     struct vnode **rvp)
  254 {
  255         struct fdesc_get_ino_args *a;
  256         struct fdescmount *fdm;
  257         struct vnode *vp;
  258         int error;
  259 
  260         a = arg;
  261         fdm = VFSTOFDESC(mp);
  262         if ((fdm->flags & FMNT_NODUP) != 0 && a->fp->f_type == DTYPE_VNODE) {
  263                 vp = a->fp->f_vnode;
  264                 vget(vp, lkflags | LK_RETRY);
  265                 *rvp = vp;
  266                 error = 0;
  267         } else {
  268                 error = fdesc_allocvp(a->ftype, a->fd_fd, a->ix, mp, rvp);
  269         }
  270         fdrop(a->fp, a->td);
  271         return (error);
  272 }
  273 
  274 /*
  275  * vp is the current namei directory
  276  * ndp is the name to locate in that directory...
  277  */
  278 static int
  279 fdesc_lookup(struct vop_lookup_args *ap)
  280 {
  281         struct vnode **vpp = ap->a_vpp;
  282         struct vnode *dvp = ap->a_dvp;
  283         struct componentname *cnp = ap->a_cnp;
  284         char *pname = cnp->cn_nameptr;
  285         struct thread *td = curthread;
  286         struct file *fp;
  287         struct fdesc_get_ino_args arg;
  288         int nlen = cnp->cn_namelen;
  289         u_int fd, fd1;
  290         int error;
  291         struct vnode *fvp;
  292 
  293         if ((cnp->cn_flags & ISLASTCN) &&
  294             (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
  295                 error = EROFS;
  296                 goto bad;
  297         }
  298 
  299         if (cnp->cn_namelen == 1 && *pname == '.') {
  300                 *vpp = dvp;
  301                 VREF(dvp);
  302                 return (0);
  303         }
  304 
  305         if (VTOFDESC(dvp)->fd_type != Froot) {
  306                 error = ENOTDIR;
  307                 goto bad;
  308         }
  309 
  310         fd = 0;
  311         /* the only time a leading 0 is acceptable is if it's "" */
  312         if (*pname == '' && nlen != 1) {
  313                 error = ENOENT;
  314                 goto bad;
  315         }
  316         while (nlen--) {
  317                 if (*pname < '' || *pname > '9') {
  318                         error = ENOENT;
  319                         goto bad;
  320                 }
  321                 fd1 = 10 * fd + *pname++ - '';
  322                 if (fd1 < fd) {
  323                         error = ENOENT;
  324                         goto bad;
  325                 }
  326                 fd = fd1;
  327         }
  328 
  329         /*
  330          * No rights to check since 'fp' isn't actually used.
  331          */
  332         if ((error = fget(td, fd, &cap_no_rights, &fp)) != 0)
  333                 goto bad;
  334 
  335         /* Check if we're looking up ourselves. */
  336         if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) {
  337                 /*
  338                  * In case we're holding the last reference to the file, the dvp
  339                  * will be re-acquired.
  340                  */
  341                 vhold(dvp);
  342                 VOP_UNLOCK(dvp);
  343                 fdrop(fp, td);
  344 
  345                 /* Re-aquire the lock afterwards. */
  346                 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
  347                 vdrop(dvp);
  348                 fvp = dvp;
  349                 if (VN_IS_DOOMED(dvp))
  350                         error = ENOENT;
  351         } else {
  352                 /*
  353                  * Unlock our root node (dvp) when doing this, since we might
  354                  * deadlock since the vnode might be locked by another thread
  355                  * and the root vnode lock will be obtained afterwards (in case
  356                  * we're looking up the fd of the root vnode), which will be the
  357                  * opposite lock order. Vhold the root vnode first so we don't
  358                  * lose it.
  359                  */
  360                 arg.ftype = Fdesc;
  361                 arg.fd_fd = fd;
  362                 arg.ix = FD_DESC + fd;
  363                 arg.fp = fp;
  364                 arg.td = td;
  365                 error = vn_vget_ino_gen(dvp, fdesc_get_ino_alloc, &arg,
  366                     LK_EXCLUSIVE, &fvp);
  367         }
  368 
  369         if (error)
  370                 goto bad;
  371         *vpp = fvp;
  372         return (0);
  373 
  374 bad:
  375         *vpp = NULL;
  376         return (error);
  377 }
  378 
  379 static int
  380 fdesc_open(struct vop_open_args *ap)
  381 {
  382         struct vnode *vp = ap->a_vp;
  383 
  384         if (VTOFDESC(vp)->fd_type == Froot)
  385                 return (0);
  386 
  387         /*
  388          * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file
  389          * descriptor being sought for duplication. The error return ensures
  390          * that the vnode for this device will be released by vn_open. Open
  391          * will detect this special error and take the actions in dupfdopen.
  392          * Other callers of vn_open or VOP_OPEN will simply report the
  393          * error.
  394          */
  395         ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd;       /* XXX */
  396         return (ENODEV);
  397 }
  398 
  399 static int
  400 fdesc_pathconf(struct vop_pathconf_args *ap)
  401 {
  402         struct vnode *vp = ap->a_vp;
  403         int error;
  404 
  405         switch (ap->a_name) {
  406         case _PC_NAME_MAX:
  407                 *ap->a_retval = NAME_MAX;
  408                 return (0);
  409         case _PC_LINK_MAX:
  410                 if (VTOFDESC(vp)->fd_type == Froot)
  411                         *ap->a_retval = 2;
  412                 else
  413                         *ap->a_retval = 1;
  414                 return (0);
  415         default:
  416                 if (VTOFDESC(vp)->fd_type == Froot)
  417                         return (vop_stdpathconf(ap));
  418                 vref(vp);
  419                 VOP_UNLOCK(vp);
  420                 error = kern_fpathconf(curthread, VTOFDESC(vp)->fd_fd,
  421                     ap->a_name, ap->a_retval);
  422                 vn_lock(vp, LK_SHARED | LK_RETRY);
  423                 vunref(vp);
  424                 return (error);
  425         }
  426 }
  427 
  428 static int
  429 fdesc_getattr(struct vop_getattr_args *ap)
  430 {
  431         struct vnode *vp = ap->a_vp;
  432         struct vattr *vap = ap->a_vap;
  433         struct timeval boottime;
  434 
  435         getboottime(&boottime);
  436         vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
  437         vap->va_fileid = VTOFDESC(vp)->fd_ix;
  438         vap->va_uid = 0;
  439         vap->va_gid = 0;
  440         vap->va_blocksize = DEV_BSIZE;
  441         vap->va_atime.tv_sec = boottime.tv_sec;
  442         vap->va_atime.tv_nsec = 0;
  443         vap->va_mtime = vap->va_atime;
  444         vap->va_ctime = vap->va_mtime;
  445         vap->va_gen = 0;
  446         vap->va_flags = 0;
  447         vap->va_bytes = 0;
  448         vap->va_filerev = 0;
  449 
  450         switch (VTOFDESC(vp)->fd_type) {
  451         case Froot:
  452                 vap->va_type = VDIR;
  453                 vap->va_nlink = 2;
  454                 vap->va_size = DEV_BSIZE;
  455                 vap->va_rdev = NODEV;
  456                 break;
  457 
  458         case Fdesc:
  459                 vap->va_type = (vp->v_vflag & VV_READLINK) == 0 ? VCHR : VLNK;
  460                 vap->va_nlink = 1;
  461                 vap->va_size = 0;
  462                 vap->va_rdev = makedev(0, vap->va_fileid);
  463                 break;
  464 
  465         default:
  466                 panic("fdesc_getattr");
  467                 break;
  468         }
  469 
  470         vp->v_type = vap->va_type;
  471         return (0);
  472 }
  473 
  474 static int
  475 fdesc_setattr(struct vop_setattr_args *ap)
  476 {
  477         struct vattr *vap = ap->a_vap;
  478         struct vnode *vp;
  479         struct mount *mp;
  480         struct file *fp;
  481         struct thread *td = curthread;
  482         cap_rights_t rights;
  483         unsigned fd;
  484         int error;
  485 
  486         /*
  487          * Can't mess with the root vnode
  488          */
  489         if (VTOFDESC(ap->a_vp)->fd_type == Froot)
  490                 return (EACCES);
  491 
  492         fd = VTOFDESC(ap->a_vp)->fd_fd;
  493 
  494         /*
  495          * Allow setattr where there is an underlying vnode.
  496          * For O_PATH descriptors, disallow truncate.
  497          */
  498         if (vap->va_size != VNOVAL) {
  499                 error = getvnode(td, fd,
  500                     cap_rights_init_one(&rights, CAP_EXTATTR_SET), &fp);
  501         } else {
  502                 error = getvnode_path(td, fd,
  503                     cap_rights_init_one(&rights, CAP_EXTATTR_SET), &fp);
  504         }
  505         if (error) {
  506                 /*
  507                  * getvnode() returns EINVAL if the file descriptor is not
  508                  * backed by a vnode.  Silently drop all changes except
  509                  * chflags(2) in this case.
  510                  */
  511                 if (error == EINVAL) {
  512                         if (vap->va_flags != VNOVAL)
  513                                 error = EOPNOTSUPP;
  514                         else
  515                                 error = 0;
  516                 }
  517                 return (error);
  518         }
  519         vp = fp->f_vnode;
  520         if ((error = vn_start_write(vp, &mp, V_WAIT | V_PCATCH)) == 0) {
  521                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  522                 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred);
  523                 VOP_UNLOCK(vp);
  524                 vn_finished_write(mp);
  525         }
  526         fdrop(fp, td);
  527         return (error);
  528 }
  529 
  530 #define UIO_MX _GENERIC_DIRLEN(10) /* number of symbols in INT_MAX printout */
  531 
  532 static int
  533 fdesc_readdir(struct vop_readdir_args *ap)
  534 {
  535         struct fdescmount *fmp;
  536         struct uio *uio = ap->a_uio;
  537         struct filedesc *fdp;
  538         struct dirent d;
  539         struct dirent *dp = &d;
  540         int error, i, off, fcnt;
  541 
  542         if (VTOFDESC(ap->a_vp)->fd_type != Froot)
  543                 panic("fdesc_readdir: not dir");
  544 
  545         fmp = VFSTOFDESC(ap->a_vp->v_mount);
  546         if (ap->a_ncookies != NULL)
  547                 *ap->a_ncookies = 0;
  548 
  549         off = (int)uio->uio_offset;
  550         if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 ||
  551             uio->uio_resid < UIO_MX)
  552                 return (EINVAL);
  553         i = (u_int)off / UIO_MX;
  554         fdp = uio->uio_td->td_proc->p_fd;
  555         error = 0;
  556 
  557         fcnt = i - 2;           /* The first two nodes are `.' and `..' */
  558 
  559         FILEDESC_SLOCK(fdp);
  560         while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) {
  561                 bzero((caddr_t)dp, UIO_MX);
  562                 switch (i) {
  563                 case 0: /* `.' */
  564                 case 1: /* `..' */
  565                         dp->d_fileno = i + FD_ROOT;
  566                         dp->d_namlen = i + 1;
  567                         dp->d_reclen = UIO_MX;
  568                         bcopy("..", dp->d_name, dp->d_namlen);
  569                         dp->d_type = DT_DIR;
  570                         dirent_terminate(dp);
  571                         break;
  572                 default:
  573                         if (fdp->fd_ofiles[fcnt].fde_file == NULL)
  574                                 break;
  575                         dp->d_namlen = sprintf(dp->d_name, "%d", fcnt);
  576                         dp->d_reclen = UIO_MX;
  577                         dp->d_type = (fmp->flags & FMNT_LINRDLNKF) == 0 ?
  578                             DT_CHR : DT_LNK;
  579                         dp->d_fileno = i + FD_DESC;
  580                         dirent_terminate(dp);
  581                         break;
  582                 }
  583                 /* NOTE: d_off is the offset of the *next* entry. */
  584                 dp->d_off = UIO_MX * (i + 1);
  585                 if (dp->d_namlen != 0) {
  586                         /*
  587                          * And ship to userland
  588                          */
  589                         FILEDESC_SUNLOCK(fdp);
  590                         error = uiomove(dp, UIO_MX, uio);
  591                         if (error)
  592                                 goto done;
  593                         FILEDESC_SLOCK(fdp);
  594                 }
  595                 i++;
  596                 fcnt++;
  597         }
  598         FILEDESC_SUNLOCK(fdp);
  599 
  600 done:
  601         uio->uio_offset = i * UIO_MX;
  602         return (error);
  603 }
  604 
  605 static int
  606 fdesc_reclaim(struct vop_reclaim_args *ap)
  607 {
  608         struct vnode *vp;
  609         struct fdescnode *fd;
  610 
  611         vp = ap->a_vp;
  612         fd = VTOFDESC(vp);
  613         fdesc_remove_entry(fd);
  614         free(vp->v_data, M_TEMP);
  615         vp->v_data = NULL;
  616         return (0);
  617 }
  618 
  619 static int
  620 fdesc_readlink(struct vop_readlink_args *va)
  621 {
  622         struct vnode *vp, *vn;
  623         struct thread *td;
  624         struct uio *uio;
  625         struct file *fp;
  626         char *freepath, *fullpath;
  627         size_t pathlen;
  628         int lockflags, fd_fd;
  629         int error;
  630 
  631         freepath = NULL;
  632         vn = va->a_vp;
  633         if (VTOFDESC(vn)->fd_type != Fdesc)
  634                 panic("fdesc_readlink: not fdescfs link");
  635         fd_fd = ((struct fdescnode *)vn->v_data)->fd_fd;
  636         lockflags = VOP_ISLOCKED(vn);
  637         VOP_UNLOCK(vn);
  638 
  639         td = curthread;
  640         error = fget_cap(td, fd_fd, &cap_no_rights, &fp, NULL);
  641         if (error != 0)
  642                 goto out;
  643 
  644         switch (fp->f_type) {
  645         case DTYPE_VNODE:
  646                 vp = fp->f_vnode;
  647                 error = vn_fullpath(vp, &fullpath, &freepath);
  648                 break;
  649         default:
  650                 fullpath = "anon_inode:[unknown]";
  651                 break;
  652         }
  653         if (error == 0) {
  654                 uio = va->a_uio;
  655                 pathlen = strlen(fullpath);
  656                 error = uiomove(fullpath, pathlen, uio);
  657         }
  658         if (freepath != NULL)
  659                 free(freepath, M_TEMP);
  660         fdrop(fp, td);
  661 
  662 out:
  663         vn_lock(vn, lockflags | LK_RETRY);
  664         return (error);
  665 }

Cache object: 068dbeebd75731827bb1bdcb76863734


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