adlookup.c revision 1.9
1 /* $NetBSD: adlookup.c,v 1.9 2006/12/09 16:11:50 chs Exp $ */ 2 3 /* 4 * Copyright (c) 1994 Christian E. Hopps 5 * Copyright (c) 1996 Matthias Scheler 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Christian E. Hopps. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __KERNEL_RCSID(0, "$NetBSD: adlookup.c,v 1.9 2006/12/09 16:11:50 chs Exp $"); 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/vnode.h> 40 #include <sys/namei.h> 41 #include <sys/mount.h> 42 #include <sys/time.h> 43 #include <sys/queue.h> 44 #include <fs/adosfs/adosfs.h> 45 46 #ifdef ADOSFS_EXACTMATCH 47 #define strmatch(s1, l1, s2, l2, i) \ 48 ((l1) == (l2) && memcmp((s1), (s2), (l1)) == 0) 49 #else 50 #define strmatch(s1, l1, s2, l2, i) \ 51 ((l1) == (l2) && adoscaseequ((s1), (s2), (l1), (i))) 52 #endif 53 54 /* 55 * adosfs lookup. enters with: 56 * pvp (parent vnode) referenced and locked. 57 * exit with: 58 * target vp referenced and locked. 59 * parent pvp locked. 60 * special cases: 61 * pvp == vp, just ref pvp, pvp already holds a ref and lock from 62 * caller, this will not occur with RENAME or CREATE. 63 */ 64 int 65 adosfs_lookup(v) 66 void *v; 67 { 68 struct vop_lookup_args /* { 69 struct vnode *a_dvp; 70 struct vnode **a_vpp; 71 struct componentname *a_cnp; 72 } */ *sp = v; 73 int nameiop, last, flags, error, nocache, i; 74 struct componentname *cnp; 75 struct vnode **vpp; /* place to store result */ 76 struct anode *ap; /* anode to find */ 77 struct vnode *vdp; /* vnode of search dir */ 78 struct anode *adp; /* anode of search dir */ 79 kauth_cred_t ucp; /* lookup credentials */ 80 u_long bn, plen, hval; 81 const u_char *pelt; 82 83 #ifdef ADOSFS_DIAGNOSTIC 84 advopprint(sp); 85 #endif 86 cnp = sp->a_cnp; 87 vdp = sp->a_dvp; 88 adp = VTOA(vdp); 89 vpp = sp->a_vpp; 90 *vpp = NULL; 91 ucp = cnp->cn_cred; 92 nameiop = cnp->cn_nameiop; 93 flags = cnp->cn_flags; 94 last = flags & ISLASTCN; 95 pelt = (const u_char *)cnp->cn_nameptr; 96 plen = cnp->cn_namelen; 97 nocache = 0; 98 99 /* 100 * Check accessiblity of directory. 101 */ 102 if ((error = VOP_ACCESS(vdp, VEXEC, ucp, cnp->cn_lwp)) != 0) 103 return (error); 104 105 if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) && 106 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 107 return (EROFS); 108 109 /* 110 * Before tediously performing a linear scan of the directory, 111 * check the name cache to see if the directory/name pair 112 * we are looking for is known already. 113 */ 114 if ((error = cache_lookup(vdp, vpp, cnp)) >= 0) 115 return (error); 116 117 /* 118 * fake a '.' 119 */ 120 if (plen == 1 && pelt[0] == '.') { 121 /* see special cases in prologue. */ 122 *vpp = vdp; 123 goto found; 124 } 125 /* 126 * fake a ".." 127 */ 128 if (flags & ISDOTDOT) { 129 if (vdp->v_type == VDIR && (vdp->v_flag & VROOT)) 130 panic("adosfs .. attempted through root"); 131 /* 132 * cannot get `..' while `vdp' is locked 133 * e.g. procA holds lock on `..' and waits for `vdp' 134 * we wait for `..' and hold lock on `vdp'. deadlock. 135 * because `vdp' may have been achieved through symlink 136 * fancy detection code that decreases the race 137 * window size is not reasonably possible. 138 * 139 * basically unlock the parent, try and lock the child (..) 140 * if that fails relock the parent (ignoring error) and 141 * fail. Otherwise we have the child (..), attempt to 142 * relock the parent. If that fails unlock the child (..) 143 * and fail. Otherwise we have succeded. 144 * 145 */ 146 VOP_UNLOCK(vdp, 0); /* race */ 147 error = VFS_VGET(vdp->v_mount, (ino_t)adp->pblock, vpp); 148 vn_lock(vdp, LK_EXCLUSIVE | LK_RETRY); 149 if (error) { 150 *vpp = NULL; 151 return (error); 152 } 153 goto found_lockdone; 154 } 155 156 /* 157 * hash the name and grab the first block in chain 158 * then walk the chain. if chain has not been fully 159 * walked before, track the count in `tabi' 160 */ 161 hval = adoshash(pelt, plen, adp->ntabent, IS_INTER(adp->amp)); 162 bn = adp->tab[hval]; 163 i = min(adp->tabi[hval], 0); 164 while (bn != 0) { 165 if ((error = VFS_VGET(vdp->v_mount, (ino_t)bn, vpp 166 )) != 0) { 167 #ifdef ADOSFS_DIAGNOSTIC 168 printf("[aget] %d)", error); 169 #endif 170 return(error); 171 } 172 ap = VTOA(*vpp); 173 if (i <= 0) { 174 if (--i < adp->tabi[hval]) 175 adp->tabi[hval] = i; 176 /* 177 * last header in chain lock count down by 178 * negating it to positive 179 */ 180 if (ap->hashf == 0) { 181 #ifdef DEBUG 182 if (i != adp->tabi[hval]) 183 panic("adlookup: wrong chain count"); 184 #endif 185 adp->tabi[hval] = -adp->tabi[hval]; 186 } 187 } 188 if (strmatch(pelt, plen, ap->name, strlen(ap->name), 189 IS_INTER(adp->amp))) 190 goto found; 191 bn = ap->hashf; 192 vput(*vpp); 193 } 194 *vpp = NULL; 195 /* 196 * not found 197 */ 198 if ((nameiop == CREATE || nameiop == RENAME) && last) { 199 200 if (vdp->v_mount->mnt_flag & MNT_RDONLY) 201 return (EROFS); 202 203 if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_lwp)) != 0) { 204 #ifdef ADOSFS_DIAGNOSTIC 205 printf("[VOP_ACCESS] %d)", error); 206 #endif 207 return (error); 208 } 209 cnp->cn_nameiop |= SAVENAME; 210 #ifdef ADOSFS_DIAGNOSTIC 211 printf("EJUSTRETURN)"); 212 #endif 213 return(EJUSTRETURN); 214 } 215 if ((cnp->cn_flags & MAKEENTRY) && nameiop != CREATE) 216 cache_enter(vdp, NULL, cnp); 217 #ifdef ADOSFS_DIAGNOSTIC 218 printf("ENOENT)"); 219 #endif 220 return(ENOENT); 221 222 found: 223 if (nameiop == DELETE && last) { 224 if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_lwp)) != 0) { 225 if (vdp != *vpp) 226 vput(*vpp); 227 *vpp = NULL; 228 return (error); 229 } 230 nocache = 1; 231 } 232 if (nameiop == RENAME && last) { 233 if (vdp == *vpp) 234 return(EISDIR); 235 if ((error = VOP_ACCESS(vdp, VWRITE, ucp, cnp->cn_lwp)) != 0) { 236 vput(*vpp); 237 *vpp = NULL; 238 return (error); 239 } 240 cnp->cn_flags |= SAVENAME; 241 nocache = 1; 242 } 243 if (vdp == *vpp) 244 VREF(vdp); 245 found_lockdone: 246 if ((cnp->cn_flags & MAKEENTRY) && nocache == 0) 247 cache_enter(vdp, *vpp, cnp); 248 249 #ifdef ADOSFS_DIAGNOSTIC 250 printf("0)\n"); 251 #endif 252 return(0); 253 } 254
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