/* $OpenBSD: cd9660_lookup.c,v 1.30 2022/01/11 03:13:58 jsg Exp $ */ /* $NetBSD: cd9660_lookup.c,v 1.18 1997/05/08 16:19:59 mycroft Exp $ */ /*- * Copyright (c) 1989, 1993, 1994 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley * by Pace Willisson (pace@blitz.com). The Rock Ridge Extension * Support code is derived from software contributed to Berkeley * by Atsushi Murai (amurai@spec.co.jp). * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: @(#)ufs_lookup.c 7.33 (Berkeley) 5/19/91 * * @(#)cd9660_lookup.c 8.5 (Berkeley) 12/5/94 */ #include <sys/param.h> #include <sys/namei.h> #include <sys/buf.h> #include <sys/vnode.h> #include <sys/lock.h> #include <sys/mount.h> #include <sys/systm.h> #include <sys/malloc.h> #include <isofs/cd9660/iso.h> #include <isofs/cd9660/cd9660_extern.h> #include <isofs/cd9660/cd9660_node.h> #include <isofs/cd9660/iso_rrip.h> struct nchstats iso_nchstats; /* * Convert a component of a pathname into a pointer to a locked inode. * This is a very central and rather complicated routine. * If the file system is not maintained in a strict tree hierarchy, * this can result in a deadlock situation (see comments in code below). * * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on * whether the name is to be looked up, created, renamed, or deleted. * When CREATE, RENAME, or DELETE is specified, information usable in * creating, renaming, or deleting a directory entry may be calculated. * If flag has LOCKPARENT or'ed into it and the target of the pathname * exists, lookup returns both the target and its parent directory locked. * When creating or renaming and LOCKPARENT is specified, the target may * not be ".". When deleting and LOCKPARENT is specified, the target may * be "."., but the caller must check to ensure it does an vrele and iput * instead of two iputs. * * Overall outline of cd9660_lookup: * * check accessibility of directory * look for name in cache, if found, then if at end of path * and deleting or creating, drop it, else return name * search for name in directory, to found or notfound * notfound: * if creating, return locked directory, leaving info on available slots * else return error * found: * if at end of path and deleting, return information to allow delete * if at end of path and rewriting (RENAME and LOCKPARENT), lock target * inode and return info to allow rewrite * if not at end, add name to cache; if at end and neither creating * nor deleting, add name to cache * * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked. */ int cd9660_lookup(void *v) { struct vop_lookup_args *ap = v; struct vnode *vdp; /* vnode for directory being searched */ struct iso_node *dp; /* inode for directory being searched */ struct iso_mnt *imp; /* file system that directory is in */ struct buf *bp; /* a buffer of directory entries */ struct iso_directory_record *ep = NULL; /* the current directory entry */ int entryoffsetinblock; /* offset of ep in bp's buffer */ int saveoffset = -1; /* offset of last directory entry in dir */ int numdirpasses; /* strategy for directory search */ doff_t endsearch; /* offset to end directory search */ struct vnode *pdp; /* saved dp during symlink work */ struct vnode *tdp; /* returned by cd9660_vget_internal */ u_long bmask; /* block offset mask */ int lockparent; /* 1 => lockparent flag is set */ int error; cdino_t ino = 0; int reclen; u_short namelen; char *altname; int res; int assoc, len; char *name; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; struct ucred *cred = cnp->cn_cred; int flags; int nameiop = cnp->cn_nameiop; cnp->cn_flags &= ~PDIRUNLOCK; flags = cnp->cn_flags; bp = NULL; *vpp = NULL; vdp = ap->a_dvp; dp = VTOI(vdp); imp = dp->i_mnt; lockparent = flags & LOCKPARENT; /* * Check accessibility of directory. */ if ((error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) != 0) return (error); if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); /* * We now have a segment name to search for, and a directory to search. * * Before tediously performing a linear scan of the directory, * check the name cache to see if the directory/name pair * we are looking for is known already. */ if ((error = cache_lookup(vdp, vpp, cnp)) >= 0) return (error); len = cnp->cn_namelen; name = cnp->cn_nameptr; /* * A leading `=' means, we are looking for an associated file */ assoc = (imp->iso_ftype != ISO_FTYPE_RRIP && *name == ASSOCCHAR); if (assoc) { len--; name++; } /* * If there is cached information on a previous search of * this directory, pick up where we last left off. * We cache only lookups as these are the most common * and have the greatest payoff. Caching CREATE has little * benefit as it usually must search the entire directory * to determine that the entry does not exist. Caching the * location of the last DELETE or RENAME has not reduced * profiling time and hence has been removed in the interest * of simplicity. */ bmask = imp->im_bmask; if (nameiop != LOOKUP || dp->i_diroff == 0 || dp->i_diroff > dp->i_size) { entryoffsetinblock = 0; dp->i_offset = 0; numdirpasses = 1; } else { dp->i_offset = dp->i_diroff; if ((entryoffsetinblock = dp->i_offset & bmask) && (error = cd9660_bufatoff(dp, (off_t)dp->i_offset, NULL, &bp))) return (error); numdirpasses = 2; iso_nchstats.ncs_2passes++; } endsearch = dp->i_size; searchloop: while (dp->i_offset < endsearch) { /* * If offset is on a block boundary, * read the next directory block. * Release previous if it exists. */ if ((dp->i_offset & bmask) == 0) { if (bp != NULL) brelse(bp); error = cd9660_bufatoff(dp, (off_t)dp->i_offset, NULL, &bp); if (error) return (error); entryoffsetinblock = 0; } /* * Get pointer to next entry. */ ep = (struct iso_directory_record *) ((char *)bp->b_data + entryoffsetinblock); reclen = isonum_711(ep->length); if (reclen == 0) { /* skip to next block, if any */ dp->i_offset = (dp->i_offset & ~bmask) + imp->logical_block_size; continue; } if (reclen < ISO_DIRECTORY_RECORD_SIZE) /* illegal entry, stop */ break; if (entryoffsetinblock + reclen > imp->logical_block_size) /* entries are not allowed to cross boundaries */ break; namelen = isonum_711(ep->name_len); if (reclen < ISO_DIRECTORY_RECORD_SIZE + namelen) /* illegal entry, stop */ break; /* * Check for a name match. */ switch (imp->iso_ftype) { default: if ((!(isonum_711(ep->flags)&4)) == !assoc) { if ((len == 1 && *name == '.') || (flags & ISDOTDOT)) { if (namelen == 1 && ep->name[0] == ((flags & ISDOTDOT) ? 1 : 0)) { /* * Save directory entry's inode number and * release directory buffer. */ dp->i_ino = isodirino(ep, imp); goto found; } if (namelen != 1 || ep->name[0] != 0) goto notfound; } else if (!(res = isofncmp(name, len, ep->name, namelen, imp->joliet_level))) { if (isonum_711(ep->flags)&2) ino = isodirino(ep, imp); else ino = dbtob(bp->b_blkno) + entryoffsetinblock; saveoffset = dp->i_offset; } else if (ino) goto foundino; #ifdef NOSORTBUG /* On some CDs directory entries are not sorted correctly */ else if (res < 0) goto notfound; else if (res > 0 && numdirpasses == 2) numdirpasses++; #endif } break; case ISO_FTYPE_RRIP: if (isonum_711(ep->flags)&2) ino = isodirino(ep, imp); else ino = dbtob(bp->b_blkno) + entryoffsetinblock; dp->i_ino = ino; altname = malloc(NAME_MAX, M_TEMP, M_WAITOK); cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); if (namelen == cnp->cn_namelen && !bcmp(name,altname,namelen)) { free(altname, M_TEMP, 0); goto found; } free(altname, M_TEMP, 0); ino = 0; break; } dp->i_offset += reclen; entryoffsetinblock += reclen; } if (ino) { foundino: dp->i_ino = ino; if (saveoffset != dp->i_offset) { if (lblkno(imp, dp->i_offset) != lblkno(imp, saveoffset)) { if (bp != NULL) brelse(bp); if ((error = cd9660_bufatoff(dp, (off_t)saveoffset, NULL, &bp)) != 0) return (error); } entryoffsetinblock = saveoffset & bmask; ep = (struct iso_directory_record *) ((char *)bp->b_data + entryoffsetinblock); dp->i_offset = saveoffset; } goto found; } notfound: /* * If we started in the middle of the directory and failed * to find our target, we must check the beginning as well. */ if (numdirpasses == 2) { numdirpasses--; dp->i_offset = 0; endsearch = dp->i_diroff; goto searchloop; } if (bp != NULL) brelse(bp); /* * Insert name into cache (as non-existent) if appropriate. */ if (cnp->cn_flags & MAKEENTRY) cache_enter(vdp, *vpp, cnp); if (nameiop == CREATE || nameiop == RENAME) return (EJUSTRETURN); return (ENOENT); found: if (numdirpasses == 2) iso_nchstats.ncs_pass2++; /* * Found component in pathname. * If the final component of path name, save information * in the cache as to where the entry was found. */ if ((flags & ISLASTCN) && nameiop == LOOKUP) dp->i_diroff = dp->i_offset; /* * Step through the translation in the name. We do not `iput' the * directory because we may need it again if a symbolic link * is relative to the current directory. Instead we save it * unlocked as "pdp". We must get the target inode before unlocking * the directory to insure that the inode will not be removed * before we get it. We prevent deadlock by always fetching * inodes from the root, moving down the directory tree. Thus * when following backward pointers ".." we must unlock the * parent directory before getting the requested directory. * There is a potential race condition here if both the current * and parent directories are removed before the `iget' for the * inode associated with ".." returns. We hope that this occurs * infrequently since we cannot avoid this race condition without * implementing a sophisticated deadlock detection algorithm. * Note also that this simple deadlock detection scheme will not * work if the file system has any hard links other than ".." * that point backwards in the directory structure. */ pdp = vdp; /* * If ino is different from dp->i_ino, * it's a relocated directory. */ if (flags & ISDOTDOT) { brelse(bp); VOP_UNLOCK(pdp); /* race to get the inode */ cnp->cn_flags |= PDIRUNLOCK; error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, dp->i_ino != ino, NULL); if (error) { if (vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY) == 0) cnp->cn_flags &= ~PDIRUNLOCK; return (error); } if (lockparent && (flags & ISLASTCN)) { if ((error = vn_lock(pdp, LK_EXCLUSIVE))) { vput(tdp); return (error); } cnp->cn_flags &= ~PDIRUNLOCK; } *vpp = tdp; } else if (dp->i_number == dp->i_ino) { brelse(bp); vref(vdp); /* we want ourself, ie "." */ *vpp = vdp; } else { error = cd9660_vget_internal(vdp->v_mount, dp->i_ino, &tdp, dp->i_ino != ino, ep); brelse(bp); if (error) return (error); if (!lockparent || !(flags & ISLASTCN)) { VOP_UNLOCK(pdp); cnp->cn_flags |= PDIRUNLOCK; } *vpp = tdp; } /* * Insert name into cache if appropriate. */ if (cnp->cn_flags & MAKEENTRY) cache_enter(vdp, *vpp, cnp); return (0); } /* * Return buffer with the contents of block "offset" from the beginning of * directory "ip". If "res" is non-zero, fill it in with a pointer to the * remaining space in the directory. */ int cd9660_bufatoff(struct iso_node *ip, off_t offset, char **res, struct buf **bpp) { struct iso_mnt *imp; struct buf *bp; daddr_t lbn; int bsize, error; struct vnode *vp = ITOV(ip); imp = ip->i_mnt; lbn = lblkno(imp, offset); bsize = blksize(imp, ip, lbn); if ((error = bread(vp, lbn, bsize, &bp)) != 0) { brelse(bp); *bpp = NULL; return (error); } if (res) *res = (char *)bp->b_data + blkoff(imp, offset); *bpp = bp; return (0); }
