/* $NetBSD: adlookup.c,v 1.9 2006/12/09 16:11:50 chs Exp $ */ /* * Copyright (c) 1994 Christian E. Hopps * Copyright (c) 1996 Matthias Scheler * All rights reserved. * * 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 Christian E. Hopps. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ #include __KERNEL_RCSID(0, "$NetBSD: adlookup.c,v 1.9 2006/12/09 16:11:50 chs Exp $"); #include #include #include #include #include #include #include #include #ifdef ADOSFS_EXACTMATCH #define strmatch(s1, l1, s2, l2, i) \ ((l1) == (l2) && memcmp((s1), (s2), (l1)) == 0) #else #define strmatch(s1, l1, s2, l2, i) \ ((l1) == (l2) && adoscaseequ((s1), (s2), (l1), (i))) #endif /* * adosfs lookup. enters with: * pvp (parent vnode) referenced and locked. * exit with: * target vp referenced and locked. * parent pvp locked. * special cases: * pvp == vp, just ref pvp, pvp already holds a ref and lock from * caller, this will not occur with RENAME or CREATE. */ int adosfs_lookup(v) void *v; { struct vop_lookup_args /* { struct vnode *a_dvp; struct vnode **a_vpp; struct componentname *a_cnp; } */ *sp = v; int nameiop, last, flags, error, nocache, i; struct componentname *cnp; struct vnode **vpp; /* place to store result */ struct anode *ap; /* anode to find */ struct vnode *vdp; /* vnode of search dir */ struct anode *adp; /* anode of search dir */ kauth_cred_t ucp; /* lookup credentials */ u_long bn, plen, hval; const u_char *pelt; #ifdef ADOSFS_DIAGNOSTIC advopprint(sp); #endif cnp = sp->a_cnp; vdp = sp->a_dvp; adp = VTOA(vdp); vpp = sp->a_vpp; *vpp = NULL; ucp = cnp->cn_cred; nameiop = cnp->cn_nameiop; flags = cnp->cn_flags; last = flags & ISLASTCN; pelt = (const u_char *)cnp->cn_nameptr; plen = cnp->cn_namelen; nocache = 0; /* * Check accessiblity of directory. */ if ((error = VOP_ACCESS(vdp, VEXEC, ucp, cnp->cn_lwp)) != 0) return (error); if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); /* * 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); /* * fake a '.' */ if (plen == 1 && pelt[0] == '.') { /* see special cases in prologue. */ *vpp = vdp; goto found; } /* * fake a ".." */ if (flags & ISDOTDOT) { if (vdp->v_type == VDIR && (vdp->v_flag & VROOT)) panic("adosfs .. attempted through root"); /* * cannot get `..' while `vdp' is locked * e.g. procA holds lock on `..' and waits for `vdp' * we wait for `..' and hold lock on `vdp'. deadlock. * because `vdp' may have been achieved through symlink * fancy detection code that decreases the race * window size is not reasonably possible. * * basically unlock the parent, try and lock the child (..) * if that fails relock the parent (ignoring error) and * fail. Otherwise we have the child (..), attempt to * relock the parent. If that fails unlock the child (..) * and fail. Otherwise we have succeded. * */ VOP_UNLOCK(vdp, 0); /* race */ error = VFS_VGET(vdp->v_mount, (ino_t)adp->pblock, vpp); vn_lock(vdp, LK_EXCLUSIVE | LK_RETRY); if (error) { *vpp = NULL; return (error); } goto found_lockdone; } /* * hash the name and grab the first block in chain * then walk the chain. if chain has not been fully * walked before, track the count in `tabi' */ hval = adoshash(pelt, plen, adp->ntabent, IS_INTER(adp->amp)); bn = adp->tab[hval]; i = min(adp->tabi[hval], 0); while (bn != 0) { if ((error = VFS_VGET(vdp->v_mount, (ino_t)bn, vpp )) != 0) { #ifdef ADOSFS_DIAGNOSTIC printf("[aget] %d)", error); #endif return(error); } ap = VTOA(*vpp); if (i <= 0) { if (--i < adp->tabi[hval]) adp->tabi[hval] = i; /* * last header in chain lock count down by * negating it to positive */ if (ap->hashf == 0) { #ifdef DEBUG if (i != adp->tabi[hval]) panic("adlookup: wrong chain count"); #endif adp->tabi[hval] = -adp->tabi[hval]; } } if (strmatch(pelt, plen, ap->name, strlen(ap->name), IS_INTER(adp->amp))) goto found; bn = ap->hashf; vput(*vpp); } *vpp = NULL; /* * not found */ if ((nameiop == CREATE || nameiop == RENAME) && last) { if (vdp->v_mount->mnt_flag & MNT_RDONLY) return (EROFS); if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_lwp)) != 0) { #ifdef ADOSFS_DIAGNOSTIC printf("[VOP_ACCESS] %d)", error); #endif return (error); } cnp->cn_nameiop |= SAVENAME; #ifdef ADOSFS_DIAGNOSTIC printf("EJUSTRETURN)"); #endif return(EJUSTRETURN); } if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE) cache_enter(vdp, NULL, cnp); #ifdef ADOSFS_DIAGNOSTIC printf("ENOENT)"); #endif return(ENOENT); found: if (nameiop == DELETE && last) { if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_lwp)) != 0) { if (vdp != *vpp) vput(*vpp); *vpp = NULL; return (error); } nocache = 1; } if (nameiop == RENAME && last) { if (vdp == *vpp) return(EISDIR); if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_lwp)) != 0) { vput(*vpp); *vpp = NULL; return (error); } cnp->cn_flags |= SAVENAME; nocache = 1; } if (vdp == *vpp) VREF(vdp); found_lockdone: if ((cnp->cn_flags & MAKEENTRY) && nocache == 0) cache_enter(vdp, *vpp, cnp); #ifdef ADOSFS_DIAGNOSTIC printf("0)\n"); #endif return(0); }