/* * Copyright (c) 1999-2012 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * Copyright (c) 1989, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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. * * @(#)hfs_lookup.c 1.0 * derived from @(#)ufs_lookup.c 8.15 (Berkeley) 6/16/95 * * (c) 1998-1999 Apple Computer, Inc. All Rights Reserved * (c) 1990, 1992 NeXT Computer, Inc. All Rights Reserved * * * hfs_lookup.c -- code to handle directory traversal on HFS/HFS+ volume */ #include <sys/param.h> #include <sys/file.h> #include <sys/mount.h> #include <sys/vnode.h> #include <sys/malloc.h> #include <sys/kdebug.h> #include <sys/kauth.h> #include <sys/namei.h> #include <sys/user.h> #include "hfs.h" #include "hfs_catalog.h" #include "hfs_cnode.h" /* * FROM FREEBSD 3.1 * Convert a component of a pathname into a pointer to a locked cnode. * 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 cnp->cn_nameiop 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. * Notice that these are the only operations that can affect the directory of the target. * * LOCKPARENT and WANTPARENT actually refer to the parent of the last item, * so if ISLASTCN is not set, they should be ignored. Also they are mutually exclusive, or * WANTPARENT really implies DONTLOCKPARENT. Either of them set means that the calling * routine wants to access the parent of the target, locked or unlocked. * * Keeping the parent locked as long as possible protects from other processes * looking up the same item, so it has to be locked until the cnode is totally finished * * hfs_cache_lookup() performs the following for us: * check that it is a directory * check accessibility of directory * check for modification attempts on read-only mounts * if name found in cache * if at end of path and deleting or creating * drop it * else * return name. * return hfs_lookup() * * Overall outline of hfs_lookup: * * handle simple cases of . and .. * 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 * cnode 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 */ /* * Lookup *cnp in directory *dvp, return it in *vpp. * **vpp is held on exit. * We create a cnode for the file, but we do NOT open the file here. #% lookup dvp L ? ? #% lookup vpp - L - IN struct vnode *dvp - Parent node of file; INOUT struct vnode **vpp - node of target file, its a new node if the target vnode did not exist; IN struct componentname *cnp - Name of file; * When should we lock parent_hp in here ?? */ static int hfs_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, int *cnode_locked) { struct cnode *dcp; /* cnode for directory being searched */ struct vnode *tvp; /* target vnode */ struct hfsmount *hfsmp; int flags; int nameiop; int retval = 0; int isDot; struct cat_desc desc; struct cat_desc cndesc; struct cat_attr attr; struct cat_fork fork; int lockflags; int newvnode_flags; retry: newvnode_flags = 0; dcp = NULL; hfsmp = VTOHFS(dvp); *vpp = NULL; *cnode_locked = 0; isDot = FALSE; tvp = NULL; nameiop = cnp->cn_nameiop; flags = cnp->cn_flags; bzero(&desc, sizeof(desc)); /* * First check to see if it is a . or .., else look it up. */ if (flags & ISDOTDOT) { /* Wanting the parent */ cnp->cn_flags &= ~MAKEENTRY; goto found; /* .. is always defined */ } else if ((cnp->cn_nameptr[0] == '.') && (cnp->cn_namelen == 1)) { isDot = TRUE; cnp->cn_flags &= ~MAKEENTRY; goto found; /* We always know who we are */ } else { if (hfs_lock(VTOC(dvp), HFS_EXCLUSIVE_LOCK) != 0) { retval = ENOENT; /* The parent no longer exists ? */ goto exit; } dcp = VTOC(dvp); if (dcp->c_flag & C_DIR_MODIFICATION) { // XXXdbg - if we could msleep on a lck_rw_t then we would do that // but since we can't we have to unlock, delay for a bit // and then retry... // msleep((caddr_t)&dcp->c_flag, &dcp->c_rwlock, PINOD, "hfs_vnop_lookup", 0); hfs_unlock(dcp); tsleep((caddr_t)dvp, PRIBIO, "hfs_lookup", 1); goto retry; } /* No need to go to catalog if there are no children */ if (dcp->c_entries == 0) { goto notfound; } bzero(&cndesc, sizeof(cndesc)); cndesc.cd_nameptr = (const u_int8_t *)cnp->cn_nameptr; cndesc.cd_namelen = cnp->cn_namelen; cndesc.cd_parentcnid = dcp->c_fileid; cndesc.cd_hint = dcp->c_childhint; lockflags = hfs_systemfile_lock(hfsmp, SFL_CATALOG, HFS_SHARED_LOCK); retval = cat_lookup(hfsmp, &cndesc, 0, &desc, &attr, &fork, NULL); hfs_systemfile_unlock(hfsmp, lockflags); if (retval == 0) { dcp->c_childhint = desc.cd_hint; /* * Note: We must drop the parent lock here before calling * hfs_getnewvnode (which takes the child lock). */ hfs_unlock(dcp); dcp = NULL; /* Verify that the item just looked up isn't one of the hidden directories. */ if (desc.cd_cnid == hfsmp->hfs_private_desc[FILE_HARDLINKS].cd_cnid || desc.cd_cnid == hfsmp->hfs_private_desc[DIR_HARDLINKS].cd_cnid) { retval = ENOENT; goto exit; } goto found; } notfound: /* * ENAMETOOLONG supersedes other errors * * For a CREATE or RENAME operation on the last component * the ENAMETOOLONG will be handled in the next VNOP. */ if ((retval != ENAMETOOLONG) && (cnp->cn_namelen > kHFSPlusMaxFileNameChars) && (((flags & ISLASTCN) == 0) || ((nameiop != CREATE) && (nameiop != RENAME)))) { retval = ENAMETOOLONG; } else if (retval == 0) { retval = ENOENT; } if (retval != ENOENT) goto exit; /* * This is a non-existing entry * * If creating, and at end of pathname and current * directory has not been removed, then can consider * allowing file to be created. */ if ((nameiop == CREATE || nameiop == RENAME || (nameiop == DELETE && (cnp->cn_flags & DOWHITEOUT) && (cnp->cn_flags & ISWHITEOUT))) && (flags & ISLASTCN) && !(ISSET(dcp->c_flag, C_DELETED | C_NOEXISTS))) { retval = EJUSTRETURN; goto exit; } /* * Insert name into the name cache (as non-existent). */ if ((hfsmp->hfs_flags & HFS_STANDARD) == 0 && (cnp->cn_flags & MAKEENTRY) && (nameiop != CREATE)) { cache_enter(dvp, NULL, cnp); dcp->c_flag |= C_NEG_ENTRIES; } goto exit; } found: if (flags & ISLASTCN) { switch(nameiop) { case DELETE: cnp->cn_flags &= ~MAKEENTRY; break; case RENAME: cnp->cn_flags &= ~MAKEENTRY; if (isDot) { retval = EISDIR; goto exit; } break; } } if (isDot) { if ((retval = vnode_get(dvp))) goto exit; *vpp = dvp; } else if (flags & ISDOTDOT) { /* * Directory hard links can have multiple parents so * find the appropriate parent for the current thread. */ if ((retval = hfs_vget(hfsmp, hfs_currentparent(VTOC(dvp)), &tvp, 0, 0))) { goto exit; } *cnode_locked = 1; *vpp = tvp; } else { int type = (attr.ca_mode & S_IFMT); if (!(flags & ISLASTCN) && (type != S_IFDIR) && (type != S_IFLNK)) { retval = ENOTDIR; goto exit; } /* Don't cache directory hardlink names. */ if (attr.ca_recflags & kHFSHasLinkChainMask) { cnp->cn_flags &= ~MAKEENTRY; } /* Names with composed chars are not cached. */ if (cnp->cn_namelen != desc.cd_namelen) cnp->cn_flags &= ~MAKEENTRY; retval = hfs_getnewvnode(hfsmp, dvp, cnp, &desc, 0, &attr, &fork, &tvp, &newvnode_flags); if (retval) { /* * If this was a create/rename operation lookup, then by this point * we expected to see the item returned from hfs_getnewvnode above. * In the create case, it would probably eventually bubble out an EEXIST * because the item existed when we were trying to create it. In the * rename case, it would let us know that we need to go ahead and * delete it as part of the rename. However, if we hit the condition below * then it means that we found the element during cat_lookup above, but * it is now no longer there. We simply behave as though we never found * the element at all and return EJUSTRETURN. */ if ((retval == ENOENT) && ((cnp->cn_nameiop == CREATE) || (cnp->cn_nameiop == RENAME)) && (flags & ISLASTCN)) { retval = EJUSTRETURN; } /* * If this was a straight lookup operation, we may need to redrive the entire * lookup starting from cat_lookup if the element was deleted as the result of * a rename operation. Since rename is supposed to guarantee atomicity, then * lookups cannot fail because the underlying element is deleted as a result of * the rename call -- either they returned the looked up element prior to rename * or return the newer element. If we are in this region, then all we can do is add * workarounds to guarantee the latter case. The element has already been deleted, so * we just re-try the lookup to ensure the caller gets the most recent element. */ if ((retval == ENOENT) && (cnp->cn_nameiop == LOOKUP) && (newvnode_flags & (GNV_CHASH_RENAMED | GNV_CAT_DELETED))) { if (dcp) { hfs_unlock (dcp); } /* get rid of any name buffers that may have lingered from the cat_lookup call */ cat_releasedesc (&desc); goto retry; } /* Also, re-drive the lookup if the item we looked up was a hardlink, and the number * or name of hardlinks has changed in the interim between the cat_lookup above, and * our call to hfs_getnewvnode. hfs_getnewvnode will validate the cattr we passed it * against what is actually in the catalog after the cnode is created. If there were * any issues, it will bubble out ERECYCLE, which we need to swallow and use as the * key to redrive as well. We need to special case this below because in this case, * it needs to occur regardless of the type of lookup we're doing here. */ if ((retval == ERECYCLE) && (newvnode_flags & GNV_CAT_ATTRCHANGED)) { if (dcp) { hfs_unlock (dcp); } /* get rid of any name buffers that may have lingered from the cat_lookup call */ cat_releasedesc (&desc); retval = 0; goto retry; } /* skip to the error-handling code if we can't retry */ goto exit; } /* * Save the origin info for file and directory hardlinks. Directory hardlinks * need the origin for '..' lookups, and file hardlinks need it to ensure that * competing lookups do not cause us to vend different hardlinks than the ones requested. * We want to restrict saving the cache entries to LOOKUP namei operations, since * we're really doing this to protect getattr. */ if ((nameiop == LOOKUP) && (VTOC(tvp)->c_flag & C_HARDLINK)) { hfs_savelinkorigin(VTOC(tvp), VTOC(dvp)->c_fileid); } *cnode_locked = 1; *vpp = tvp; } exit: if (dcp) { hfs_unlock(dcp); } cat_releasedesc(&desc); return (retval); } /* * Name caching works as follows: * * Names found by directory scans are retained in a cache * for future reference. It is managed LRU, so frequently * used names will hang around. Cache is indexed by hash value * obtained from (vp, name) where vp refers to the directory * containing name. * * If it is a "negative" entry, (i.e. for a name that is known NOT to * exist) the vnode pointer will be NULL. * * Upon reaching the last segment of a path, if the reference * is for DELETE, or NOCACHE is set (rewrite), and the * name is located in the cache, it will be dropped. * */ #define S_IXALL 0000111 int hfs_vnop_lookup(struct vnop_lookup_args *ap) { struct vnode *dvp = ap->a_dvp; struct vnode *vp; struct cnode *cp; struct cnode *dcp; struct hfsmount *hfsmp; int error; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; int flags = cnp->cn_flags; int cnode_locked; *vpp = NULL; dcp = VTOC(dvp); hfsmp = VTOHFS(dvp); /* * Lookup an entry in the cache * * If the lookup succeeds, the vnode is returned in *vpp, * and a status of -1 is returned. * * If the lookup determines that the name does not exist * (negative cacheing), a status of ENOENT is returned. * * If the lookup fails, a status of zero is returned. */ error = cache_lookup(dvp, vpp, cnp); if (error != -1) { if ((error == ENOENT) && (cnp->cn_nameiop != CREATE)) goto exit; /* found a negative cache entry */ goto lookup; /* did not find it in the cache */ } /* * We have a name that matched * cache_lookup returns the vp with an iocount reference already taken */ error = 0; vp = *vpp; cp = VTOC(vp); /* We aren't allowed to vend out vp's via lookup to the hidden directory */ if (cp->c_cnid == hfsmp->hfs_private_desc[FILE_HARDLINKS].cd_cnid || cp->c_cnid == hfsmp->hfs_private_desc[DIR_HARDLINKS].cd_cnid) { /* Drop the iocount from cache_lookup */ vnode_put (vp); error = ENOENT; goto exit; } /* * If this is a hard-link vnode then we need to update * the name (of the link), the parent ID, the cnid, the * text encoding and the catalog hint. This enables * getattrlist calls to return the correct link info. */ if ((flags & ISLASTCN) && (cp->c_flag & C_HARDLINK)) { int stale_link = 0; hfs_lock(cp, HFS_FORCE_LOCK); if ((cp->c_parentcnid != dcp->c_cnid) || (bcmp(cnp->cn_nameptr, cp->c_desc.cd_nameptr, cp->c_desc.cd_namelen) != 0)) { struct cat_desc desc; struct cat_attr lookup_attr; int lockflags; /* * Get an updated descriptor */ desc.cd_nameptr = (const u_int8_t *)cnp->cn_nameptr; desc.cd_namelen = cnp->cn_namelen; desc.cd_parentcnid = dcp->c_fileid; desc.cd_hint = dcp->c_childhint; desc.cd_encoding = 0; desc.cd_cnid = 0; desc.cd_flags = S_ISDIR(cp->c_mode) ? CD_ISDIR : 0; /* * Because lookups call replace_desc to put a new descriptor in * the cnode we are modifying it is possible that this cnode's * descriptor is out of date for the parent ID / name that * we are trying to look up. (It may point to a different hardlink). * * We need to be cautious that when re-supplying the * descriptor below that the results of the catalog lookup * still point to the same raw inode for the hardlink. This would * not be the case if we found something in the cache above but * the vnode it returned no longer has a valid hardlink for the * parent ID/filename combo we are requesting. (This is because * hfs_unlink does not directly trigger namecache removal). * * As a result, before vending out the vnode (and replacing * its descriptor) verify that the fileID is the same by comparing * the in-cnode attributes vs. the one returned from the lookup call * below. If they do not match, treat this lookup as if we never hit * in the cache at all. */ lockflags = hfs_systemfile_lock(VTOHFS(dvp), SFL_CATALOG, HFS_SHARED_LOCK); error = cat_lookup(VTOHFS(vp), &desc, 0, &desc, &lookup_attr, NULL, NULL); hfs_systemfile_unlock(VTOHFS(dvp), lockflags); /* * Note that cat_lookup may fail to find something with the name provided in the * stack-based descriptor above. In that case, an ENOENT is a legitimate errno * to be placed in error, which will get returned in the fastpath below. */ if (error == 0) { if (lookup_attr.ca_fileid == cp->c_attr.ca_fileid) { /* It still points to the right raw inode. Replacing the descriptor is fine */ replace_desc (cp, &desc); /* * Save the origin info for file and directory hardlinks. Directory hardlinks * need the origin for '..' lookups, and file hardlinks need it to ensure that * competing lookups do not cause us to vend different hardlinks than the ones requested. * We want to restrict saving the cache entries to LOOKUP namei operations, since * we're really doing this to protect getattr. */ if (cnp->cn_nameiop == LOOKUP) { hfs_savelinkorigin(cp, dcp->c_fileid); } } else { /* If the fileID does not match then do NOT replace the descriptor! */ stale_link = 1; } } } hfs_unlock (cp); if (stale_link) { /* * If we had a stale_link, then we need to pretend as though * we never found this vnode and force a lookup through the * traditional path. Drop the iocount acquired through * cache_lookup above and force a cat lookup / getnewvnode */ vnode_put(vp); goto lookup; } if (error) { /* * If the cat_lookup failed then the caller will not expect * a vnode with an iocount on it. */ vnode_put(vp); } } goto exit; lookup: /* * The vnode was not in the name cache or it was stale. * * So we need to do a real lookup. */ cnode_locked = 0; error = hfs_lookup(dvp, vpp, cnp, &cnode_locked); if (cnode_locked) hfs_unlock(VTOC(*vpp)); exit: { uthread_t ut = (struct uthread *)get_bsdthread_info(current_thread()); /* * check to see if we issued any I/O while completing this lookup and * this thread/task is throttleable... if so, throttle now * * this allows us to throttle in between multiple meta data reads that * might result due to looking up a long pathname (since we'll have to * re-enter hfs_vnop_lookup for each component of the pathnam not in * the VFS cache), instead of waiting until the entire path lookup has * completed and throttling at the systemcall return */ if (__improbable(ut->uu_lowpri_window)) { throttle_lowpri_io(TRUE); } } return (error); }