/* $NetBSD: cd9660_lookup.c,v 1.33 2024/09/08 09:36:51 rillig 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) 5/27/95 */ #include <sys/cdefs.h> __KERNEL_RCSID(0, "$NetBSD: cd9660_lookup.c,v 1.33 2024/09/08 09:36:51 rillig Exp $"); #include <sys/param.h> #include <sys/namei.h> #include <sys/buf.h> #include <sys/file.h> #include <sys/vnode.h> #include <sys/mount.h> #include <sys/systm.h> #include <sys/kauth.h> #include <fs/cd9660/iso.h> #include <fs/cd9660/cd9660_extern.h> #include <fs/cd9660/cd9660_node.h> #include <fs/cd9660/iso_rrip.h> #include <fs/cd9660/cd9660_rrip.h> #include <fs/cd9660/cd9660_mount.h> /* * 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 the target of the pathname exists, lookup returns both the target * and its parent directory locked. * When creating or renaming, the target may * not be ".". * When deleting , the target may be "."., but the caller must check * to ensure it does a vrele and vput instead of two vputs. * * Overall outline of ufs_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), 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 */ int cd9660_lookup(void *v) { struct vop_lookup_v2_args /* { struct vnode *a_dvp; struct vnode **a_vpp; struct componentname *a_cnp; } */ *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 *tdp; /* returned by vcache_get */ u_long bmask; /* block offset mask */ int error; ino_t ino = 0; int reclen; u_short namelen; char altname[ISO_MAXNAMLEN]; int res; int assoc, len; const char *name; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; kauth_cred_t cred = cnp->cn_cred; int flags; int nameiop = cnp->cn_nameiop; flags = cnp->cn_flags; bp = NULL; *vpp = NULL; vdp = ap->a_dvp; dp = VTOI(vdp); imp = dp->i_mnt; /* * Check accessibility of directory. */ if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 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 (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) { return *vpp == NULLVP ? ENOENT : 0; } /* May need to restart the lookup with an exclusive lock. */ if (VOP_ISLOCKED(vdp) != LK_EXCLUSIVE) return ENOLCK; 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_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp))) return (error); numdirpasses = 2; namecache_count_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, 0); error = cd9660_blkatoff(vdp, (off_t)dp->i_offset, NULL, &bp); if (error) return (error); entryoffsetinblock = 0; } /* * Get pointer to next entry. */ KASSERT(bp != NULL); 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->im_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; cd9660_rrip_getname(ep,altname,&namelen,&dp->i_ino,imp); if (namelen == cnp->cn_namelen) { if (imp->im_flags & ISOFSMNT_RRCASEINS) { if (strncasecmp(name, altname, namelen) == 0) goto found; } else { if (memcmp(name, altname, namelen) == 0) goto found; } } ino = 0; break; } dp->i_offset += reclen; entryoffsetinblock += reclen; } if (ino) { foundino: dp->i_ino = ino; if (saveoffset != dp->i_offset) { if (cd9660_lblkno(imp, dp->i_offset) != cd9660_lblkno(imp, saveoffset)) { if (bp != NULL) brelse(bp, 0); if ((error = cd9660_blkatoff(vdp, (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, 0); /* * Insert name into cache (as non-existent) if appropriate. */ cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags); return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT; found: if (numdirpasses == 2) namecache_count_pass2(); brelse(bp, 0); /* * 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; if (dp->i_number == dp->i_ino) { vref(vdp); /* we want ourself, ie "." */ *vpp = vdp; } else { error = vcache_get(vdp->v_mount, &dp->i_ino, sizeof(dp->i_ino), &tdp); if (error) return (error); *vpp = tdp; } /* * Insert name into cache if appropriate. */ cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags); 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_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp) { struct iso_node *ip; struct iso_mnt *imp; struct vnode *devvp; struct buf *bp; daddr_t lbn; int bsize, error; ip = VTOI(vp); imp = ip->i_mnt; lbn = cd9660_lblkno(imp, offset); bsize = cd9660_blksize(imp, ip, lbn); if ((error = VOP_BMAP(vp, lbn, &devvp, &lbn, NULL)) != 0) { *bpp = NULL; return error; } if ((error = bread(devvp, lbn, bsize, 0, &bp)) != 0) { *bpp = NULL; return (error); } if (res) *res = (char *)bp->b_data + cd9660_blkoff(imp, offset); *bpp = bp; return (0); }
