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vfs_lookup.c revision 1.41
      1  1.41     soren /*	$NetBSD: vfs_lookup.c,v 1.41 2002/08/02 04:49:35 soren Exp $	*/
      2  1.13       cgd 
      3  1.10       cgd /*
      4  1.12   mycroft  * Copyright (c) 1982, 1986, 1989, 1993
      5  1.12   mycroft  *	The Regents of the University of California.  All rights reserved.
      6  1.10       cgd  * (c) UNIX System Laboratories, Inc.
      7  1.10       cgd  * All or some portions of this file are derived from material licensed
      8  1.10       cgd  * to the University of California by American Telephone and Telegraph
      9  1.10       cgd  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     10  1.10       cgd  * the permission of UNIX System Laboratories, Inc.
     11  1.10       cgd  *
     12  1.10       cgd  * Redistribution and use in source and binary forms, with or without
     13  1.10       cgd  * modification, are permitted provided that the following conditions
     14  1.10       cgd  * are met:
     15  1.10       cgd  * 1. Redistributions of source code must retain the above copyright
     16  1.10       cgd  *    notice, this list of conditions and the following disclaimer.
     17  1.10       cgd  * 2. Redistributions in binary form must reproduce the above copyright
     18  1.10       cgd  *    notice, this list of conditions and the following disclaimer in the
     19  1.10       cgd  *    documentation and/or other materials provided with the distribution.
     20  1.10       cgd  * 3. All advertising materials mentioning features or use of this software
     21  1.10       cgd  *    must display the following acknowledgement:
     22  1.10       cgd  *	This product includes software developed by the University of
     23  1.10       cgd  *	California, Berkeley and its contributors.
     24  1.10       cgd  * 4. Neither the name of the University nor the names of its contributors
     25  1.10       cgd  *    may be used to endorse or promote products derived from this software
     26  1.10       cgd  *    without specific prior written permission.
     27  1.10       cgd  *
     28  1.10       cgd  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     29  1.10       cgd  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     30  1.10       cgd  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     31  1.10       cgd  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     32  1.10       cgd  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     33  1.10       cgd  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     34  1.10       cgd  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     35  1.10       cgd  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     36  1.10       cgd  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     37  1.10       cgd  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     38  1.10       cgd  * SUCH DAMAGE.
     39  1.10       cgd  *
     40  1.26      fvdl  *	@(#)vfs_lookup.c	8.10 (Berkeley) 5/27/95
     41  1.10       cgd  */
     42  1.38     lukem 
     43  1.38     lukem #include <sys/cdefs.h>
     44  1.41     soren __KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.41 2002/08/02 04:49:35 soren Exp $");
     45  1.27   thorpej 
     46  1.27   thorpej #include "opt_ktrace.h"
     47  1.10       cgd 
     48  1.10       cgd #include <sys/param.h>
     49  1.15       cgd #include <sys/systm.h>
     50  1.10       cgd #include <sys/syslimits.h>
     51  1.10       cgd #include <sys/time.h>
     52  1.10       cgd #include <sys/namei.h>
     53  1.10       cgd #include <sys/vnode.h>
     54  1.10       cgd #include <sys/mount.h>
     55  1.10       cgd #include <sys/errno.h>
     56  1.39     lukem #include <sys/filedesc.h>
     57  1.39     lukem #include <sys/hash.h>
     58  1.10       cgd #include <sys/malloc.h>
     59  1.10       cgd #include <sys/proc.h>
     60  1.40  wrstuden #include <sys/syslog.h>
     61  1.12   mycroft 
     62  1.10       cgd #ifdef KTRACE
     63  1.10       cgd #include <sys/ktrace.h>
     64  1.10       cgd #endif
     65  1.16  christos 
     66  1.35   thorpej struct pool pnbuf_pool;		/* pathname buffer pool */
     67  1.37   thorpej struct pool_cache pnbuf_cache;	/* pathname buffer cache */
     68  1.35   thorpej 
     69  1.10       cgd /*
     70  1.10       cgd  * Convert a pathname into a pointer to a locked inode.
     71  1.10       cgd  *
     72  1.10       cgd  * The FOLLOW flag is set when symbolic links are to be followed
     73  1.10       cgd  * when they occur at the end of the name translation process.
     74  1.10       cgd  * Symbolic links are always followed for all other pathname
     75  1.10       cgd  * components other than the last.
     76  1.10       cgd  *
     77  1.10       cgd  * The segflg defines whether the name is to be copied from user
     78  1.10       cgd  * space or kernel space.
     79  1.10       cgd  *
     80  1.10       cgd  * Overall outline of namei:
     81  1.10       cgd  *
     82  1.10       cgd  *	copy in name
     83  1.10       cgd  *	get starting directory
     84  1.10       cgd  *	while (!done && !error) {
     85  1.10       cgd  *		call lookup to search path.
     86  1.10       cgd  *		if symbolic link, massage name in buffer and continue
     87  1.10       cgd  *	}
     88  1.10       cgd  */
     89  1.12   mycroft int
     90  1.12   mycroft namei(ndp)
     91  1.33  augustss 	struct nameidata *ndp;
     92  1.10       cgd {
     93  1.30   thorpej 	struct cwdinfo *cwdi;		/* pointer to cwd state */
     94  1.33  augustss 	char *cp;			/* pointer into pathname argument */
     95  1.33  augustss 	struct vnode *dp;		/* the directory we are searching */
     96  1.10       cgd 	struct iovec aiov;		/* uio for reading symbolic links */
     97  1.10       cgd 	struct uio auio;
     98  1.23   mycroft 	int error, linklen;
     99  1.12   mycroft 	struct componentname *cnp = &ndp->ni_cnd;
    100  1.10       cgd 
    101  1.12   mycroft #ifdef DIAGNOSTIC
    102  1.12   mycroft 	if (!cnp->cn_cred || !cnp->cn_proc)
    103  1.12   mycroft 		panic ("namei: bad cred/proc");
    104  1.12   mycroft 	if (cnp->cn_nameiop & (~OPMASK))
    105  1.12   mycroft 		panic ("namei: nameiop contaminated with flags");
    106  1.12   mycroft 	if (cnp->cn_flags & OPMASK)
    107  1.12   mycroft 		panic ("namei: flags contaminated with nameiops");
    108  1.12   mycroft #endif
    109  1.30   thorpej 	cwdi = cnp->cn_proc->p_cwdi;
    110  1.10       cgd 
    111  1.10       cgd 	/*
    112  1.10       cgd 	 * Get a buffer for the name to be translated, and copy the
    113  1.10       cgd 	 * name into the buffer.
    114  1.10       cgd 	 */
    115  1.12   mycroft 	if ((cnp->cn_flags & HASBUF) == 0)
    116  1.35   thorpej 		cnp->cn_pnbuf = PNBUF_GET();
    117  1.10       cgd 	if (ndp->ni_segflg == UIO_SYSSPACE)
    118  1.12   mycroft 		error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
    119  1.10       cgd 			    MAXPATHLEN, &ndp->ni_pathlen);
    120  1.10       cgd 	else
    121  1.12   mycroft 		error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
    122  1.10       cgd 			    MAXPATHLEN, &ndp->ni_pathlen);
    123  1.21    kleink 
    124  1.21    kleink 	/*
    125  1.21    kleink 	 * POSIX.1 requirement: "" is not a valid file name.
    126  1.21    kleink 	 */
    127  1.21    kleink 	if (!error && ndp->ni_pathlen == 1)
    128  1.21    kleink 		error = ENOENT;
    129  1.21    kleink 
    130  1.10       cgd 	if (error) {
    131  1.35   thorpej 		PNBUF_PUT(cnp->cn_pnbuf);
    132  1.10       cgd 		ndp->ni_vp = NULL;
    133  1.10       cgd 		return (error);
    134  1.10       cgd 	}
    135  1.10       cgd 	ndp->ni_loopcnt = 0;
    136  1.21    kleink 
    137  1.10       cgd #ifdef KTRACE
    138  1.12   mycroft 	if (KTRPOINT(cnp->cn_proc, KTR_NAMEI))
    139  1.34  sommerfe 		ktrnamei(cnp->cn_proc, cnp->cn_pnbuf);
    140  1.10       cgd #endif
    141  1.10       cgd 
    142  1.10       cgd 	/*
    143  1.10       cgd 	 * Get starting point for the translation.
    144  1.10       cgd 	 */
    145  1.30   thorpej 	if ((ndp->ni_rootdir = cwdi->cwdi_rdir) == NULL)
    146  1.11       cgd 		ndp->ni_rootdir = rootvnode;
    147  1.23   mycroft 	/*
    148  1.23   mycroft 	 * Check if starting from root directory or current directory.
    149  1.23   mycroft 	 */
    150  1.23   mycroft 	if (cnp->cn_pnbuf[0] == '/') {
    151  1.23   mycroft 		dp = ndp->ni_rootdir;
    152  1.23   mycroft 		VREF(dp);
    153  1.23   mycroft 	} else {
    154  1.30   thorpej 		dp = cwdi->cwdi_cdir;
    155  1.23   mycroft 		VREF(dp);
    156  1.23   mycroft 	}
    157  1.10       cgd 	for (;;) {
    158  1.12   mycroft 		cnp->cn_nameptr = cnp->cn_pnbuf;
    159  1.10       cgd 		ndp->ni_startdir = dp;
    160  1.16  christos 		if ((error = lookup(ndp)) != 0) {
    161  1.35   thorpej 			PNBUF_PUT(cnp->cn_pnbuf);
    162  1.10       cgd 			return (error);
    163  1.10       cgd 		}
    164  1.10       cgd 		/*
    165  1.10       cgd 		 * Check for symbolic link
    166  1.10       cgd 		 */
    167  1.12   mycroft 		if ((cnp->cn_flags & ISSYMLINK) == 0) {
    168  1.12   mycroft 			if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0)
    169  1.35   thorpej 				PNBUF_PUT(cnp->cn_pnbuf);
    170  1.10       cgd 			else
    171  1.12   mycroft 				cnp->cn_flags |= HASBUF;
    172  1.10       cgd 			return (0);
    173  1.10       cgd 		}
    174  1.29  wrstuden 		if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN))
    175  1.26      fvdl 			VOP_UNLOCK(ndp->ni_dvp, 0);
    176  1.10       cgd 		if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
    177  1.10       cgd 			error = ELOOP;
    178  1.10       cgd 			break;
    179  1.10       cgd 		}
    180  1.25     enami 		if (ndp->ni_vp->v_mount->mnt_flag & MNT_SYMPERM) {
    181  1.25     enami 			error = VOP_ACCESS(ndp->ni_vp, VEXEC, cnp->cn_cred,
    182  1.25     enami 			    cnp->cn_proc);
    183  1.25     enami 			if (error != 0)
    184  1.25     enami 				break;
    185  1.25     enami 		}
    186  1.10       cgd 		if (ndp->ni_pathlen > 1)
    187  1.35   thorpej 			cp = PNBUF_GET();
    188  1.10       cgd 		else
    189  1.12   mycroft 			cp = cnp->cn_pnbuf;
    190  1.10       cgd 		aiov.iov_base = cp;
    191  1.10       cgd 		aiov.iov_len = MAXPATHLEN;
    192  1.10       cgd 		auio.uio_iov = &aiov;
    193  1.10       cgd 		auio.uio_iovcnt = 1;
    194  1.10       cgd 		auio.uio_offset = 0;
    195  1.10       cgd 		auio.uio_rw = UIO_READ;
    196  1.10       cgd 		auio.uio_segflg = UIO_SYSSPACE;
    197  1.10       cgd 		auio.uio_procp = (struct proc *)0;
    198  1.10       cgd 		auio.uio_resid = MAXPATHLEN;
    199  1.16  christos 		error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
    200  1.16  christos 		if (error) {
    201  1.23   mycroft 		badlink:
    202  1.10       cgd 			if (ndp->ni_pathlen > 1)
    203  1.35   thorpej 				PNBUF_PUT(cp);
    204  1.10       cgd 			break;
    205  1.10       cgd 		}
    206  1.10       cgd 		linklen = MAXPATHLEN - auio.uio_resid;
    207  1.23   mycroft 		if (linklen == 0) {
    208  1.23   mycroft 			error = ENOENT;
    209  1.23   mycroft 			goto badlink;
    210  1.23   mycroft 		}
    211  1.10       cgd 		if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
    212  1.10       cgd 			error = ENAMETOOLONG;
    213  1.23   mycroft 			goto badlink;
    214  1.10       cgd 		}
    215  1.10       cgd 		if (ndp->ni_pathlen > 1) {
    216  1.28     perry 			memcpy(cp + linklen, ndp->ni_next, ndp->ni_pathlen);
    217  1.35   thorpej 			PNBUF_PUT(cnp->cn_pnbuf);
    218  1.12   mycroft 			cnp->cn_pnbuf = cp;
    219  1.10       cgd 		} else
    220  1.12   mycroft 			cnp->cn_pnbuf[linklen] = '\0';
    221  1.10       cgd 		ndp->ni_pathlen += linklen;
    222  1.10       cgd 		vput(ndp->ni_vp);
    223  1.10       cgd 		dp = ndp->ni_dvp;
    224  1.23   mycroft 		/*
    225  1.23   mycroft 		 * Check if root directory should replace current directory.
    226  1.23   mycroft 		 */
    227  1.23   mycroft 		if (cnp->cn_pnbuf[0] == '/') {
    228  1.23   mycroft 			vrele(dp);
    229  1.23   mycroft 			dp = ndp->ni_rootdir;
    230  1.23   mycroft 			VREF(dp);
    231  1.23   mycroft 		}
    232  1.10       cgd 	}
    233  1.35   thorpej 	PNBUF_PUT(cnp->cn_pnbuf);
    234  1.10       cgd 	vrele(ndp->ni_dvp);
    235  1.10       cgd 	vput(ndp->ni_vp);
    236  1.10       cgd 	ndp->ni_vp = NULL;
    237  1.10       cgd 	return (error);
    238  1.10       cgd }
    239  1.10       cgd 
    240  1.10       cgd /*
    241  1.39     lukem  * Determine the namei hash (for cn_hash) for name.
    242  1.39     lukem  * If *ep != NULL, hash from name to ep-1.
    243  1.39     lukem  * If *ep == NULL, hash from name until the first NUL or '/', and
    244  1.39     lukem  * return the location of this termination character in *ep.
    245  1.39     lukem  *
    246  1.39     lukem  * This function returns an equivalent hash to the MI hash32_strn().
    247  1.39     lukem  * The latter isn't used because in the *ep == NULL case, determining
    248  1.39     lukem  * the length of the string to the first NUL or `/' and then calling
    249  1.39     lukem  * hash32_strn() involves unnecessary double-handling of the data.
    250  1.39     lukem  */
    251  1.39     lukem uint32_t
    252  1.39     lukem namei_hash(const char *name, const char **ep)
    253  1.39     lukem {
    254  1.39     lukem 	uint32_t	hash;
    255  1.39     lukem 
    256  1.39     lukem 	hash = HASH32_STR_INIT;
    257  1.39     lukem 	if (*ep != NULL) {
    258  1.39     lukem 		for (; name < *ep; name++)
    259  1.39     lukem 			hash = hash * 33 + *(uint8_t *)name;
    260  1.39     lukem 	} else {
    261  1.39     lukem 		for (; *name != '\0' && *name != '/'; name++)
    262  1.39     lukem 			hash = hash * 33 + *(uint8_t *)name;
    263  1.39     lukem 		*ep = name;
    264  1.39     lukem 	}
    265  1.39     lukem 	return (hash + (hash >> 5));
    266  1.39     lukem }
    267  1.39     lukem 
    268  1.39     lukem /*
    269  1.10       cgd  * Search a pathname.
    270  1.10       cgd  * This is a very central and rather complicated routine.
    271  1.10       cgd  *
    272  1.10       cgd  * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
    273  1.10       cgd  * The starting directory is taken from ni_startdir. The pathname is
    274  1.10       cgd  * descended until done, or a symbolic link is encountered. The variable
    275  1.10       cgd  * ni_more is clear if the path is completed; it is set to one if a
    276  1.10       cgd  * symbolic link needing interpretation is encountered.
    277  1.10       cgd  *
    278  1.10       cgd  * The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
    279  1.10       cgd  * whether the name is to be looked up, created, renamed, or deleted.
    280  1.10       cgd  * When CREATE, RENAME, or DELETE is specified, information usable in
    281  1.10       cgd  * creating, renaming, or deleting a directory entry may be calculated.
    282  1.10       cgd  * If flag has LOCKPARENT or'ed into it, the parent directory is returned
    283  1.10       cgd  * locked. If flag has WANTPARENT or'ed into it, the parent directory is
    284  1.10       cgd  * returned unlocked. Otherwise the parent directory is not returned. If
    285  1.10       cgd  * the target of the pathname exists and LOCKLEAF is or'ed into the flag
    286  1.10       cgd  * the target is returned locked, otherwise it is returned unlocked.
    287  1.10       cgd  * When creating or renaming and LOCKPARENT is specified, the target may not
    288  1.10       cgd  * be ".".  When deleting and LOCKPARENT is specified, the target may be ".".
    289  1.10       cgd  *
    290  1.10       cgd  * Overall outline of lookup:
    291  1.10       cgd  *
    292  1.10       cgd  * dirloop:
    293  1.10       cgd  *	identify next component of name at ndp->ni_ptr
    294  1.10       cgd  *	handle degenerate case where name is null string
    295  1.10       cgd  *	if .. and crossing mount points and on mounted filesys, find parent
    296  1.10       cgd  *	call VOP_LOOKUP routine for next component name
    297  1.10       cgd  *	    directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
    298  1.10       cgd  *	    component vnode returned in ni_vp (if it exists), locked.
    299  1.10       cgd  *	if result vnode is mounted on and crossing mount points,
    300  1.10       cgd  *	    find mounted on vnode
    301  1.10       cgd  *	if more components of name, do next level at dirloop
    302  1.10       cgd  *	return the answer in ni_vp, locked if LOCKLEAF set
    303  1.10       cgd  *	    if LOCKPARENT set, return locked parent in ni_dvp
    304  1.10       cgd  *	    if WANTPARENT set, return unlocked parent in ni_dvp
    305  1.10       cgd  */
    306  1.12   mycroft int
    307  1.12   mycroft lookup(ndp)
    308  1.33  augustss 	struct nameidata *ndp;
    309  1.10       cgd {
    310  1.33  augustss 	const char *cp;			/* pointer into pathname argument */
    311  1.33  augustss 	struct vnode *dp = 0;		/* the directory we are searching */
    312  1.10       cgd 	struct vnode *tdp;		/* saved dp */
    313  1.10       cgd 	struct mount *mp;		/* mount table entry */
    314  1.10       cgd 	int docache;			/* == 0 do not cache last component */
    315  1.10       cgd 	int wantparent;			/* 1 => wantparent or lockparent flag */
    316  1.12   mycroft 	int rdonly;			/* lookup read-only flag bit */
    317  1.10       cgd 	int error = 0;
    318  1.23   mycroft 	int slashes;
    319  1.32  wrstuden 	int dpunlocked = 0;		/* dp has already been unlocked */
    320  1.12   mycroft 	struct componentname *cnp = &ndp->ni_cnd;
    321  1.10       cgd 
    322  1.10       cgd 	/*
    323  1.10       cgd 	 * Setup: break out flag bits into variables.
    324  1.10       cgd 	 */
    325  1.12   mycroft 	wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
    326  1.12   mycroft 	docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
    327  1.12   mycroft 	if (cnp->cn_nameiop == DELETE ||
    328  1.12   mycroft 	    (wantparent && cnp->cn_nameiop != CREATE))
    329  1.10       cgd 		docache = 0;
    330  1.12   mycroft 	rdonly = cnp->cn_flags & RDONLY;
    331  1.10       cgd 	ndp->ni_dvp = NULL;
    332  1.12   mycroft 	cnp->cn_flags &= ~ISSYMLINK;
    333  1.10       cgd 	dp = ndp->ni_startdir;
    334  1.10       cgd 	ndp->ni_startdir = NULLVP;
    335  1.26      fvdl 	vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
    336  1.10       cgd 
    337  1.23   mycroft 	/*
    338  1.23   mycroft 	 * If we have a leading string of slashes, remove them, and just make
    339  1.23   mycroft 	 * sure the current node is a directory.
    340  1.23   mycroft 	 */
    341  1.23   mycroft 	cp = cnp->cn_nameptr;
    342  1.23   mycroft 	if (*cp == '/') {
    343  1.23   mycroft 		do {
    344  1.23   mycroft 			cp++;
    345  1.23   mycroft 		} while (*cp == '/');
    346  1.23   mycroft 		ndp->ni_pathlen -= cp - cnp->cn_nameptr;
    347  1.23   mycroft 		cnp->cn_nameptr = cp;
    348  1.23   mycroft 
    349  1.23   mycroft 		if (dp->v_type != VDIR) {
    350  1.23   mycroft 			error = ENOTDIR;
    351  1.23   mycroft 			goto bad;
    352  1.23   mycroft 		}
    353  1.23   mycroft 
    354  1.23   mycroft 		/*
    355  1.23   mycroft 		 * If we've exhausted the path name, then just return the
    356  1.23   mycroft 		 * current node.  If the caller requested the parent node (i.e.
    357  1.23   mycroft 		 * it's a CREATE, DELETE, or RENAME), and we don't have one
    358  1.23   mycroft 		 * (because this is the root directory), then we must fail.
    359  1.23   mycroft 		 */
    360  1.23   mycroft 		if (cnp->cn_nameptr[0] == '\0') {
    361  1.23   mycroft 			if (ndp->ni_dvp == NULL && wantparent) {
    362  1.23   mycroft 				error = EISDIR;
    363  1.23   mycroft 				goto bad;
    364  1.23   mycroft 			}
    365  1.23   mycroft 			ndp->ni_vp = dp;
    366  1.23   mycroft 			cnp->cn_flags |= ISLASTCN;
    367  1.23   mycroft 			goto terminal;
    368  1.23   mycroft 		}
    369  1.23   mycroft 	}
    370  1.23   mycroft 
    371  1.10       cgd dirloop:
    372  1.10       cgd 	/*
    373  1.10       cgd 	 * Search a new directory.
    374  1.10       cgd 	 *
    375  1.12   mycroft 	 * The cn_hash value is for use by vfs_cache.
    376  1.10       cgd 	 * The last component of the filename is left accessible via
    377  1.12   mycroft 	 * cnp->cn_nameptr for callers that need the name. Callers needing
    378  1.10       cgd 	 * the name set the SAVENAME flag. When done, they assume
    379  1.10       cgd 	 * responsibility for freeing the pathname buffer.
    380  1.10       cgd 	 */
    381  1.12   mycroft 	cnp->cn_consume = 0;
    382  1.39     lukem 	cp = NULL;
    383  1.39     lukem 	cnp->cn_hash = namei_hash(cnp->cn_nameptr, &cp);
    384  1.12   mycroft 	cnp->cn_namelen = cp - cnp->cn_nameptr;
    385  1.12   mycroft 	if (cnp->cn_namelen > NAME_MAX) {
    386  1.10       cgd 		error = ENAMETOOLONG;
    387  1.10       cgd 		goto bad;
    388  1.10       cgd 	}
    389  1.10       cgd #ifdef NAMEI_DIAGNOSTIC
    390  1.10       cgd 	{ char c = *cp;
    391  1.41     soren 	*(char *)cp = '\0';
    392  1.19  christos 	printf("{%s}: ", cnp->cn_nameptr);
    393  1.41     soren 	*(char *)cp = c; }
    394  1.10       cgd #endif
    395  1.12   mycroft 	ndp->ni_pathlen -= cnp->cn_namelen;
    396  1.10       cgd 	ndp->ni_next = cp;
    397  1.23   mycroft 	/*
    398  1.23   mycroft 	 * If this component is followed by a slash, then move the pointer to
    399  1.23   mycroft 	 * the next component forward, and remember that this component must be
    400  1.23   mycroft 	 * a directory.
    401  1.23   mycroft 	 */
    402  1.23   mycroft 	if (*cp == '/') {
    403  1.23   mycroft 		do {
    404  1.23   mycroft 			cp++;
    405  1.23   mycroft 		} while (*cp == '/');
    406  1.23   mycroft 		slashes = cp - ndp->ni_next;
    407  1.23   mycroft 		ndp->ni_pathlen -= slashes;
    408  1.23   mycroft 		ndp->ni_next = cp;
    409  1.23   mycroft 		cnp->cn_flags |= REQUIREDIR;
    410  1.23   mycroft 	} else {
    411  1.23   mycroft 		slashes = 0;
    412  1.23   mycroft 		cnp->cn_flags &= ~REQUIREDIR;
    413  1.23   mycroft 	}
    414  1.23   mycroft 	/*
    415  1.23   mycroft 	 * We do special processing on the last component, whether or not it's
    416  1.23   mycroft 	 * a directory.  Cache all intervening lookups, but not the final one.
    417  1.23   mycroft 	 */
    418  1.23   mycroft 	if (*cp == '\0') {
    419  1.23   mycroft 		if (docache)
    420  1.23   mycroft 			cnp->cn_flags |= MAKEENTRY;
    421  1.23   mycroft 		else
    422  1.23   mycroft 			cnp->cn_flags &= ~MAKEENTRY;
    423  1.23   mycroft 		cnp->cn_flags |= ISLASTCN;
    424  1.23   mycroft 	} else {
    425  1.23   mycroft 		cnp->cn_flags |= MAKEENTRY;
    426  1.23   mycroft 		cnp->cn_flags &= ~ISLASTCN;
    427  1.23   mycroft 	}
    428  1.12   mycroft 	if (cnp->cn_namelen == 2 &&
    429  1.12   mycroft 	    cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
    430  1.12   mycroft 		cnp->cn_flags |= ISDOTDOT;
    431  1.12   mycroft 	else
    432  1.12   mycroft 		cnp->cn_flags &= ~ISDOTDOT;
    433  1.10       cgd 
    434  1.10       cgd 	/*
    435  1.10       cgd 	 * Handle "..": two special cases.
    436  1.10       cgd 	 * 1. If at root directory (e.g. after chroot)
    437  1.12   mycroft 	 *    or at absolute root directory
    438  1.10       cgd 	 *    then ignore it so can't get out.
    439  1.40  wrstuden 	 * 1a. If we have somehow gotten out of a jail, warn
    440  1.40  wrstuden 	 *    and also ignore it so we can't get farther out.
    441  1.10       cgd 	 * 2. If this vnode is the root of a mounted
    442  1.10       cgd 	 *    filesystem, then replace it with the
    443  1.10       cgd 	 *    vnode which was mounted on so we take the
    444  1.10       cgd 	 *    .. in the other file system.
    445  1.10       cgd 	 */
    446  1.12   mycroft 	if (cnp->cn_flags & ISDOTDOT) {
    447  1.10       cgd 		for (;;) {
    448  1.12   mycroft 			if (dp == ndp->ni_rootdir || dp == rootvnode) {
    449  1.10       cgd 				ndp->ni_dvp = dp;
    450  1.10       cgd 				ndp->ni_vp = dp;
    451  1.10       cgd 				VREF(dp);
    452  1.10       cgd 				goto nextname;
    453  1.40  wrstuden 			}
    454  1.40  wrstuden 			if (ndp->ni_rootdir != rootvnode) {
    455  1.40  wrstuden 				int retval;
    456  1.40  wrstuden 				VOP_UNLOCK(dp, 0);
    457  1.40  wrstuden 				retval = vn_isunder(dp, ndp->ni_rootdir,
    458  1.40  wrstuden 				    cnp->cn_proc);
    459  1.40  wrstuden 				vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
    460  1.40  wrstuden 				if (!retval) {
    461  1.40  wrstuden 				    /* Oops! We got out of jail! */
    462  1.40  wrstuden 				    log(LOG_WARNING,
    463  1.40  wrstuden 					"chrooted pid %d uid %d (%s) "
    464  1.40  wrstuden 					"detected outside of its chroot\n",
    465  1.40  wrstuden 					cnp->cn_proc->p_pid,
    466  1.40  wrstuden 					cnp->cn_proc->p_ucred->cr_uid,
    467  1.40  wrstuden 					cnp->cn_proc->p_comm);
    468  1.40  wrstuden 				    /* Put us at the jail root. */
    469  1.40  wrstuden 				    vput(dp);
    470  1.40  wrstuden 				    dp = ndp->ni_rootdir;
    471  1.40  wrstuden 				    ndp->ni_dvp = dp;
    472  1.40  wrstuden 				    ndp->ni_vp = dp;
    473  1.40  wrstuden 				    VREF(dp);
    474  1.40  wrstuden 				    VREF(dp);
    475  1.40  wrstuden 				    vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
    476  1.40  wrstuden 				    goto nextname;
    477  1.40  wrstuden 				}
    478  1.10       cgd 			}
    479  1.10       cgd 			if ((dp->v_flag & VROOT) == 0 ||
    480  1.12   mycroft 			    (cnp->cn_flags & NOCROSSMOUNT))
    481  1.10       cgd 				break;
    482  1.10       cgd 			tdp = dp;
    483  1.10       cgd 			dp = dp->v_mount->mnt_vnodecovered;
    484  1.10       cgd 			vput(tdp);
    485  1.10       cgd 			VREF(dp);
    486  1.26      fvdl 			vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
    487  1.10       cgd 		}
    488  1.10       cgd 	}
    489  1.10       cgd 
    490  1.10       cgd 	/*
    491  1.10       cgd 	 * We now have a segment name to search for, and a directory to search.
    492  1.10       cgd 	 */
    493  1.12   mycroft unionlookup:
    494  1.12   mycroft 	ndp->ni_dvp = dp;
    495  1.26      fvdl 	ndp->ni_vp = NULL;
    496  1.31  wrstuden 	cnp->cn_flags &= ~PDIRUNLOCK;
    497  1.16  christos 	if ((error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) != 0) {
    498  1.10       cgd #ifdef DIAGNOSTIC
    499  1.10       cgd 		if (ndp->ni_vp != NULL)
    500  1.10       cgd 			panic("leaf should be empty");
    501  1.10       cgd #endif
    502  1.10       cgd #ifdef NAMEI_DIAGNOSTIC
    503  1.19  christos 		printf("not found\n");
    504  1.10       cgd #endif
    505  1.12   mycroft 		if ((error == ENOENT) &&
    506  1.10       cgd 		    (dp->v_flag & VROOT) &&
    507  1.10       cgd 		    (dp->v_mount->mnt_flag & MNT_UNION)) {
    508  1.10       cgd 			tdp = dp;
    509  1.10       cgd 			dp = dp->v_mount->mnt_vnodecovered;
    510  1.31  wrstuden 			if (cnp->cn_flags & PDIRUNLOCK)
    511  1.31  wrstuden 				vrele(tdp);
    512  1.31  wrstuden 			else
    513  1.31  wrstuden 				vput(tdp);
    514  1.10       cgd 			VREF(dp);
    515  1.26      fvdl 			vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
    516  1.12   mycroft 			goto unionlookup;
    517  1.10       cgd 		}
    518  1.12   mycroft 
    519  1.10       cgd 		if (error != EJUSTRETURN)
    520  1.10       cgd 			goto bad;
    521  1.10       cgd 		/*
    522  1.23   mycroft 		 * If this was not the last component, or there were trailing
    523  1.23   mycroft 		 * slashes, then the name must exist.
    524  1.23   mycroft 		 */
    525  1.23   mycroft 		if (cnp->cn_flags & REQUIREDIR) {
    526  1.23   mycroft 			error = ENOENT;
    527  1.23   mycroft 			goto bad;
    528  1.23   mycroft 		}
    529  1.23   mycroft 		/*
    530  1.10       cgd 		 * If creating and at end of pathname, then can consider
    531  1.10       cgd 		 * allowing file to be created.
    532  1.10       cgd 		 */
    533  1.26      fvdl 		if (rdonly) {
    534  1.10       cgd 			error = EROFS;
    535  1.10       cgd 			goto bad;
    536  1.10       cgd 		}
    537  1.10       cgd 		/*
    538  1.10       cgd 		 * We return with ni_vp NULL to indicate that the entry
    539  1.10       cgd 		 * doesn't currently exist, leaving a pointer to the
    540  1.10       cgd 		 * (possibly locked) directory inode in ndp->ni_dvp.
    541  1.10       cgd 		 */
    542  1.12   mycroft 		if (cnp->cn_flags & SAVESTART) {
    543  1.10       cgd 			ndp->ni_startdir = ndp->ni_dvp;
    544  1.10       cgd 			VREF(ndp->ni_startdir);
    545  1.10       cgd 		}
    546  1.10       cgd 		return (0);
    547  1.10       cgd 	}
    548  1.10       cgd #ifdef NAMEI_DIAGNOSTIC
    549  1.19  christos 	printf("found\n");
    550  1.10       cgd #endif
    551  1.10       cgd 
    552  1.12   mycroft 	/*
    553  1.23   mycroft 	 * Take into account any additional components consumed by the
    554  1.23   mycroft 	 * underlying filesystem.  This will include any trailing slashes after
    555  1.23   mycroft 	 * the last component consumed.
    556  1.12   mycroft 	 */
    557  1.12   mycroft 	if (cnp->cn_consume > 0) {
    558  1.23   mycroft 		ndp->ni_pathlen -= cnp->cn_consume - slashes;
    559  1.23   mycroft 		ndp->ni_next += cnp->cn_consume - slashes;
    560  1.12   mycroft 		cnp->cn_consume = 0;
    561  1.23   mycroft 		if (ndp->ni_next[0] == '\0')
    562  1.23   mycroft 			cnp->cn_flags |= ISLASTCN;
    563  1.12   mycroft 	}
    564  1.12   mycroft 
    565  1.10       cgd 	dp = ndp->ni_vp;
    566  1.10       cgd 	/*
    567  1.10       cgd 	 * Check to see if the vnode has been mounted on;
    568  1.10       cgd 	 * if so find the root of the mounted file system.
    569  1.10       cgd 	 */
    570  1.10       cgd 	while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
    571  1.12   mycroft 	       (cnp->cn_flags & NOCROSSMOUNT) == 0) {
    572  1.26      fvdl 		if (vfs_busy(mp, 0, 0))
    573  1.12   mycroft 			continue;
    574  1.32  wrstuden 		VOP_UNLOCK(dp, 0);
    575  1.26      fvdl 		error = VFS_ROOT(mp, &tdp);
    576  1.26      fvdl 		vfs_unbusy(mp);
    577  1.32  wrstuden 		if (error) {
    578  1.32  wrstuden 			dpunlocked = 1;
    579  1.10       cgd 			goto bad2;
    580  1.32  wrstuden 		}
    581  1.32  wrstuden 		vrele(dp);
    582  1.10       cgd 		ndp->ni_vp = dp = tdp;
    583  1.14   mycroft 	}
    584  1.14   mycroft 
    585  1.14   mycroft 	/*
    586  1.23   mycroft 	 * Check for symbolic link.  Back up over any slashes that we skipped,
    587  1.23   mycroft 	 * as we will need them again.
    588  1.14   mycroft 	 */
    589  1.23   mycroft 	if ((dp->v_type == VLNK) && (cnp->cn_flags & (FOLLOW|REQUIREDIR))) {
    590  1.23   mycroft 		ndp->ni_pathlen += slashes;
    591  1.23   mycroft 		ndp->ni_next -= slashes;
    592  1.14   mycroft 		cnp->cn_flags |= ISSYMLINK;
    593  1.14   mycroft 		return (0);
    594  1.10       cgd 	}
    595  1.10       cgd 
    596  1.23   mycroft 	/*
    597  1.23   mycroft 	 * Check for directory, if the component was followed by a series of
    598  1.23   mycroft 	 * slashes.
    599  1.23   mycroft 	 */
    600  1.23   mycroft 	if ((dp->v_type != VDIR) && (cnp->cn_flags & REQUIREDIR)) {
    601  1.23   mycroft 		error = ENOTDIR;
    602  1.23   mycroft 		goto bad2;
    603  1.23   mycroft 	}
    604  1.23   mycroft 
    605  1.10       cgd nextname:
    606  1.10       cgd 	/*
    607  1.23   mycroft 	 * Not a symbolic link.  If this was not the last component, then
    608  1.23   mycroft 	 * continue at the next component, else return.
    609  1.10       cgd 	 */
    610  1.23   mycroft 	if (!(cnp->cn_flags & ISLASTCN)) {
    611  1.12   mycroft 		cnp->cn_nameptr = ndp->ni_next;
    612  1.10       cgd 		vrele(ndp->ni_dvp);
    613  1.10       cgd 		goto dirloop;
    614  1.10       cgd 	}
    615  1.23   mycroft 
    616  1.23   mycroft terminal:
    617  1.10       cgd 	/*
    618  1.26      fvdl 	 * Disallow directory write attempts on read-only file systems.
    619  1.10       cgd 	 */
    620  1.26      fvdl 	if (rdonly &&
    621  1.26      fvdl 	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
    622  1.10       cgd 		/*
    623  1.10       cgd 		 * Disallow directory write attempts on read-only
    624  1.10       cgd 		 * file systems.
    625  1.10       cgd 		 */
    626  1.26      fvdl 		error = EROFS;
    627  1.26      fvdl 		goto bad2;
    628  1.10       cgd 	}
    629  1.23   mycroft 	if (ndp->ni_dvp != NULL) {
    630  1.23   mycroft 		if (cnp->cn_flags & SAVESTART) {
    631  1.23   mycroft 			ndp->ni_startdir = ndp->ni_dvp;
    632  1.23   mycroft 			VREF(ndp->ni_startdir);
    633  1.23   mycroft 		}
    634  1.23   mycroft 		if (!wantparent)
    635  1.23   mycroft 			vrele(ndp->ni_dvp);
    636  1.10       cgd 	}
    637  1.12   mycroft 	if ((cnp->cn_flags & LOCKLEAF) == 0)
    638  1.26      fvdl 		VOP_UNLOCK(dp, 0);
    639  1.10       cgd 	return (0);
    640  1.10       cgd 
    641  1.10       cgd bad2:
    642  1.31  wrstuden 	if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN) &&
    643  1.31  wrstuden 			((cnp->cn_flags & PDIRUNLOCK) == 0))
    644  1.26      fvdl 		VOP_UNLOCK(ndp->ni_dvp, 0);
    645  1.10       cgd 	vrele(ndp->ni_dvp);
    646  1.10       cgd bad:
    647  1.32  wrstuden 	if (dpunlocked)
    648  1.32  wrstuden 		vrele(dp);
    649  1.32  wrstuden 	else
    650  1.32  wrstuden 		vput(dp);
    651  1.10       cgd 	ndp->ni_vp = NULL;
    652  1.12   mycroft 	return (error);
    653  1.12   mycroft }
    654  1.12   mycroft 
    655  1.12   mycroft /*
    656  1.12   mycroft  * Reacquire a path name component.
    657  1.12   mycroft  */
    658  1.12   mycroft int
    659  1.12   mycroft relookup(dvp, vpp, cnp)
    660  1.12   mycroft 	struct vnode *dvp, **vpp;
    661  1.12   mycroft 	struct componentname *cnp;
    662  1.12   mycroft {
    663  1.26      fvdl 	struct vnode *dp = 0;		/* the directory we are searching */
    664  1.12   mycroft 	int docache;			/* == 0 do not cache last component */
    665  1.12   mycroft 	int wantparent;			/* 1 => wantparent or lockparent flag */
    666  1.12   mycroft 	int rdonly;			/* lookup read-only flag bit */
    667  1.12   mycroft 	int error = 0;
    668  1.12   mycroft #ifdef NAMEI_DIAGNOSTIC
    669  1.12   mycroft 	int newhash;			/* DEBUG: check name hash */
    670  1.41     soren 	const char *cp;			/* DEBUG: check name ptr/len */
    671  1.12   mycroft #endif
    672  1.12   mycroft 
    673  1.12   mycroft 	/*
    674  1.12   mycroft 	 * Setup: break out flag bits into variables.
    675  1.12   mycroft 	 */
    676  1.12   mycroft 	wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
    677  1.12   mycroft 	docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
    678  1.12   mycroft 	if (cnp->cn_nameiop == DELETE ||
    679  1.12   mycroft 	    (wantparent && cnp->cn_nameiop != CREATE))
    680  1.12   mycroft 		docache = 0;
    681  1.12   mycroft 	rdonly = cnp->cn_flags & RDONLY;
    682  1.12   mycroft 	cnp->cn_flags &= ~ISSYMLINK;
    683  1.12   mycroft 	dp = dvp;
    684  1.26      fvdl 	vn_lock(dp, LK_EXCLUSIVE | LK_RETRY);
    685  1.12   mycroft 
    686  1.12   mycroft /* dirloop: */
    687  1.12   mycroft 	/*
    688  1.12   mycroft 	 * Search a new directory.
    689  1.12   mycroft 	 *
    690  1.12   mycroft 	 * The cn_hash value is for use by vfs_cache.
    691  1.12   mycroft 	 * The last component of the filename is left accessible via
    692  1.12   mycroft 	 * cnp->cn_nameptr for callers that need the name. Callers needing
    693  1.12   mycroft 	 * the name set the SAVENAME flag. When done, they assume
    694  1.12   mycroft 	 * responsibility for freeing the pathname buffer.
    695  1.12   mycroft 	 */
    696  1.12   mycroft #ifdef NAMEI_DIAGNOSTIC
    697  1.39     lukem 	cp = NULL;
    698  1.39     lukem 	newhash = namei_hash(cnp->cn_nameptr, &cp);
    699  1.12   mycroft 	if (newhash != cnp->cn_hash)
    700  1.12   mycroft 		panic("relookup: bad hash");
    701  1.12   mycroft 	if (cnp->cn_namelen != cp - cnp->cn_nameptr)
    702  1.12   mycroft 		panic ("relookup: bad len");
    703  1.12   mycroft 	if (*cp != 0)
    704  1.12   mycroft 		panic("relookup: not last component");
    705  1.19  christos 	printf("{%s}: ", cnp->cn_nameptr);
    706  1.12   mycroft #endif
    707  1.12   mycroft 
    708  1.12   mycroft 	/*
    709  1.12   mycroft 	 * Check for degenerate name (e.g. / or "")
    710  1.12   mycroft 	 * which is a way of talking about a directory,
    711  1.12   mycroft 	 * e.g. like "/." or ".".
    712  1.12   mycroft 	 */
    713  1.23   mycroft 	if (cnp->cn_nameptr[0] == '\0')
    714  1.23   mycroft 		panic("relookup: null name");
    715  1.12   mycroft 
    716  1.12   mycroft 	if (cnp->cn_flags & ISDOTDOT)
    717  1.12   mycroft 		panic ("relookup: lookup on dot-dot");
    718  1.12   mycroft 
    719  1.12   mycroft 	/*
    720  1.12   mycroft 	 * We now have a segment name to search for, and a directory to search.
    721  1.12   mycroft 	 */
    722  1.16  christos 	if ((error = VOP_LOOKUP(dp, vpp, cnp)) != 0) {
    723  1.12   mycroft #ifdef DIAGNOSTIC
    724  1.12   mycroft 		if (*vpp != NULL)
    725  1.12   mycroft 			panic("leaf should be empty");
    726  1.12   mycroft #endif
    727  1.12   mycroft 		if (error != EJUSTRETURN)
    728  1.12   mycroft 			goto bad;
    729  1.12   mycroft 		/*
    730  1.12   mycroft 		 * If creating and at end of pathname, then can consider
    731  1.12   mycroft 		 * allowing file to be created.
    732  1.12   mycroft 		 */
    733  1.26      fvdl 		if (rdonly) {
    734  1.12   mycroft 			error = EROFS;
    735  1.12   mycroft 			goto bad;
    736  1.12   mycroft 		}
    737  1.12   mycroft 		/* ASSERT(dvp == ndp->ni_startdir) */
    738  1.12   mycroft 		if (cnp->cn_flags & SAVESTART)
    739  1.12   mycroft 			VREF(dvp);
    740  1.12   mycroft 		/*
    741  1.12   mycroft 		 * We return with ni_vp NULL to indicate that the entry
    742  1.12   mycroft 		 * doesn't currently exist, leaving a pointer to the
    743  1.12   mycroft 		 * (possibly locked) directory inode in ndp->ni_dvp.
    744  1.12   mycroft 		 */
    745  1.12   mycroft 		return (0);
    746  1.12   mycroft 	}
    747  1.12   mycroft 	dp = *vpp;
    748  1.12   mycroft 
    749  1.12   mycroft #ifdef DIAGNOSTIC
    750  1.12   mycroft 	/*
    751  1.12   mycroft 	 * Check for symbolic link
    752  1.12   mycroft 	 */
    753  1.12   mycroft 	if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW))
    754  1.12   mycroft 		panic ("relookup: symlink found.\n");
    755  1.12   mycroft #endif
    756  1.12   mycroft 
    757  1.12   mycroft 	/*
    758  1.12   mycroft 	 * Check for read-only file systems.
    759  1.12   mycroft 	 */
    760  1.26      fvdl 	if (rdonly &&
    761  1.26      fvdl 	    (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
    762  1.26      fvdl 		error = EROFS;
    763  1.26      fvdl 		goto bad2;
    764  1.12   mycroft 	}
    765  1.12   mycroft 	/* ASSERT(dvp == ndp->ni_startdir) */
    766  1.12   mycroft 	if (cnp->cn_flags & SAVESTART)
    767  1.12   mycroft 		VREF(dvp);
    768  1.12   mycroft 	if (!wantparent)
    769  1.12   mycroft 		vrele(dvp);
    770  1.12   mycroft 	if ((cnp->cn_flags & LOCKLEAF) == 0)
    771  1.26      fvdl 		VOP_UNLOCK(dp, 0);
    772  1.12   mycroft 	return (0);
    773  1.12   mycroft 
    774  1.12   mycroft bad2:
    775  1.12   mycroft 	if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN))
    776  1.26      fvdl 		VOP_UNLOCK(dvp, 0);
    777  1.12   mycroft 	vrele(dvp);
    778  1.12   mycroft bad:
    779  1.12   mycroft 	vput(dp);
    780  1.12   mycroft 	*vpp = NULL;
    781  1.10       cgd 	return (error);
    782  1.10       cgd }
    783