[unix-history] / sys / kern / vfs_lookup.c

/*
 * Copyright (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.
 */
/*
 * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
 * 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 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.
 *
 *	from: @(#)vfs_lookup.c	7.32 (Berkeley) 5/21/91
 *	$Id: vfs_lookup.c,v 1.5 1993/11/25 01:33:41 wollman Exp $
 */

#include "param.h"
#include "systm.h"
#include "syslimits.h"
#include "time.h"
#include "namei.h"
#include "vnode.h"
#include "mount.h"
#include "errno.h"
#include "malloc.h"
#include "filedesc.h"
#include "proc.h"

#ifdef KTRACE
#include "ktrace.h"
#endif

u_long nextvnodeid;

/*
 * Convert a pathname into a pointer to a locked inode.
 *
 * The FOLLOW flag is set when symbolic links are to be followed
 * when they occur at the end of the name translation process.
 * Symbolic links are always followed for all other pathname
 * components other than the last.
 *
 * The segflg defines whether the name is to be copied from user
 * space or kernel space.
 *
 * Overall outline of namei:
 *
 *	copy in name
 *	get starting directory
 *	while (!done && !error) {
 *		call lookup to search path.
 *		if symbolic link, massage name in buffer and continue
 *	}
 */
int
namei(ndp, p)
	register struct nameidata *ndp;
	struct proc *p;
{
	register struct filedesc *fdp;	/* pointer to file descriptor state */
	register char *cp;		/* pointer into pathname argument */
	register struct vnode *dp;	/* the directory we are searching */
	struct iovec aiov;		/* uio for reading symbolic links */
	struct uio auio;
	int error, linklen;

	ndp->ni_cred = p->p_ucred;
	fdp = p->p_fd;

	/*
	 * Get a buffer for the name to be translated, and copy the
	 * name into the buffer.
	 */
	if ((ndp->ni_nameiop & HASBUF) == 0)
		MALLOC(ndp->ni_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
	if (ndp->ni_segflg == UIO_SYSSPACE)
		error = copystr(ndp->ni_dirp, ndp->ni_pnbuf,
			    MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
	else
		error = copyinstr(ndp->ni_dirp, ndp->ni_pnbuf,
			    MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
	if (error) {
		free(ndp->ni_pnbuf, M_NAMEI);
		ndp->ni_vp = NULL;
		return (error);
	}
	ndp->ni_loopcnt = 0;
#ifdef KTRACE
	if (KTRPOINT(p, KTR_NAMEI))
		ktrnamei(p->p_tracep, ndp->ni_pnbuf);
#endif

	/*
	 * Get starting point for the translation.
	 */
	if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL)
		ndp->ni_rootdir = rootdir;
	dp = fdp->fd_cdir;
	VREF(dp);
	for (;;) {
		/*
		 * Check if root directory should replace current directory.
		 * Done at start of translation and after symbolic link.
		 */
		ndp->ni_ptr = ndp->ni_pnbuf;
		if (*ndp->ni_ptr == '/') {
			vrele(dp);
			while (*ndp->ni_ptr == '/') {
				ndp->ni_ptr++;
				ndp->ni_pathlen--;
			}
			dp = ndp->ni_rootdir;
			VREF(dp);
		}
		ndp->ni_startdir = dp;
		if (error = lookup(ndp, p)) {
			FREE(ndp->ni_pnbuf, M_NAMEI);
			return (error);
		}
		/*
		 * Check for symbolic link
		 */
		if (ndp->ni_more == 0) {
			if ((ndp->ni_nameiop & (SAVENAME | SAVESTART)) == 0)
				FREE(ndp->ni_pnbuf, M_NAMEI);
			else
				ndp->ni_nameiop |= HASBUF;
			return (0);
		}
		if ((ndp->ni_nameiop & LOCKPARENT) && ndp->ni_pathlen == 1)
			VOP_UNLOCK(ndp->ni_dvp);
		if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
			error = ELOOP;
			break;
		}
		if (ndp->ni_pathlen > 1)
			MALLOC(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
		else
			cp = ndp->ni_pnbuf;
		aiov.iov_base = cp;
		aiov.iov_len = MAXPATHLEN;
		auio.uio_iov = &aiov;
		auio.uio_iovcnt = 1;
		auio.uio_offset = 0;
		auio.uio_rw = UIO_READ;
		auio.uio_segflg = UIO_SYSSPACE;
		auio.uio_procp = (struct proc *)0;
		auio.uio_resid = MAXPATHLEN;
		if (error = VOP_READLINK(ndp->ni_vp, &auio, p->p_ucred)) {
			if (ndp->ni_pathlen > 1)
				free(cp, M_NAMEI);
			break;
		}
		linklen = MAXPATHLEN - auio.uio_resid;
		if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
			if (ndp->ni_pathlen > 1)
				free(cp, M_NAMEI);
			error = ENAMETOOLONG;
			break;
		}
		if (ndp->ni_pathlen > 1) {
			bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
			FREE(ndp->ni_pnbuf, M_NAMEI);
			ndp->ni_pnbuf = cp;
		} else
			ndp->ni_pnbuf[linklen] = '\0';
		ndp->ni_pathlen += linklen;
		vput(ndp->ni_vp);
		dp = ndp->ni_dvp;
	}
	FREE(ndp->ni_pnbuf, M_NAMEI);
	vrele(ndp->ni_dvp);
	vput(ndp->ni_vp);
	ndp->ni_vp = NULL;
	return (error);
}

/*
 * Search a pathname.
 * This is a very central and rather complicated routine.
 *
 * The pathname is pointed to by ni_ptr and is of length ni_pathlen.
 * The starting directory is taken from ni_startdir. The pathname is
 * descended until done, or a symbolic link is encountered. The variable
 * ni_more is clear if the path is completed; it is set to one if a
 * symbolic link needing interpretation is encountered.
 *
 * 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 flag has LOCKPARENT or'ed into it, the parent directory is returned
 * locked. If flag has WANTPARENT or'ed into it, the parent directory is
 * returned unlocked. Otherwise the parent directory is not returned. If
 * the target of the pathname exists and LOCKLEAF is or'ed into the flag
 * the target is returned locked, otherwise it is returned unlocked.
 * When creating or renaming and LOCKPARENT is specified, the target may not
 * be ".".  When deleting and LOCKPARENT is specified, the target may be ".".
 * NOTE: (LOOKUP | LOCKPARENT) currently returns the parent vnode unlocked.
 * 
 * Overall outline of lookup:
 *
 * dirloop:
 *	identify next component of name at ndp->ni_ptr
 *	handle degenerate case where name is null string
 *	if .. and crossing mount points and on mounted filesys, find parent
 *	call VOP_LOOKUP routine for next component name
 *	    directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
 *	    component vnode returned in ni_vp (if it exists), locked.
 *	if result vnode is mounted on and crossing mount points,
 *	    find mounted on vnode
 *	if more components of name, do next level at dirloop
 *	return the answer in ni_vp, locked if LOCKLEAF set
 *	    if LOCKPARENT set, return locked parent in ni_dvp
 *	    if WANTPARENT set, return unlocked parent in ni_dvp
 */
int
lookup(ndp, p)
	register struct nameidata *ndp;
	struct proc *p;
{
	register char *cp;		/* pointer into pathname argument */
	register struct vnode *dp = 0;	/* the directory we are searching */
	struct vnode *tdp;		/* saved dp */
	struct mount *mp;		/* mount table entry */
	int docache;			/* == 0 do not cache last component */
	int flag;			/* LOOKUP, CREATE, RENAME or DELETE */
	int wantparent;			/* 1 => wantparent or lockparent flag */
	int rdonly;			/* mounted read-only flag bit(s) */
	int error = 0;

	/*
	 * Setup: break out flag bits into variables.
	 */
	flag = ndp->ni_nameiop & OPMASK;
	wantparent = ndp->ni_nameiop & (LOCKPARENT|WANTPARENT);
	docache = (ndp->ni_nameiop & NOCACHE) ^ NOCACHE;
	if (flag == DELETE || (wantparent && flag != CREATE))
		docache = 0;
	rdonly = MNT_RDONLY;
	if (ndp->ni_nameiop & REMOTE)
		rdonly |= MNT_EXRDONLY;
	ndp->ni_dvp = NULL;
	ndp->ni_more = 0;
	dp = ndp->ni_startdir;
	ndp->ni_startdir = NULLVP;
	VOP_LOCK(dp);

dirloop:
	/*
	 * Search a new directory.
	 *
	 * The ni_hash value is for use by vfs_cache.
	 * The last component of the filename is left accessible via
	 * ndp->ptr for callers that need the name. Callers needing
	 * the name set the SAVENAME flag. When done, they assume
	 * responsibility for freeing the pathname buffer.
	 */
	ndp->ni_hash = 0;
	for (cp = ndp->ni_ptr; *cp != 0 && *cp != '/'; cp++)
		ndp->ni_hash += (unsigned char)*cp;
	ndp->ni_namelen = cp - ndp->ni_ptr;
	if (ndp->ni_namelen >= NAME_MAX) {
		error = ENAMETOOLONG;
		goto bad;
	}
#ifdef NAMEI_DIAGNOSTIC
	{ char c = *cp;
	*cp = '\0';
	printf("{%s}: ", ndp->ni_ptr);
	*cp = c; }
#endif
	ndp->ni_pathlen -= ndp->ni_namelen;
	ndp->ni_next = cp;
	ndp->ni_makeentry = 1;
	if (*cp == '\0' && docache == 0)
		ndp->ni_makeentry = 0;
	ndp->ni_isdotdot = (ndp->ni_namelen == 2 &&
		ndp->ni_ptr[1] == '.' && ndp->ni_ptr[0] == '.');

	/*
	 * Check for degenerate name (e.g. / or "")
	 * which is a way of talking about a directory,
	 * e.g. like "/." or ".".
	 */
	if (ndp->ni_ptr[0] == '\0') {
		if (flag != LOOKUP || wantparent) {
			error = EISDIR;
			goto bad;
		}
		if (dp->v_type != VDIR) {
			error = ENOTDIR;
			goto bad;
		}
		if (!(ndp->ni_nameiop & LOCKLEAF))
			VOP_UNLOCK(dp);
		ndp->ni_vp = dp;
		if (ndp->ni_nameiop & SAVESTART)
			panic("lookup: SAVESTART");
		return (0);
	}

	/*
	 * Handle "..": two special cases.
	 * 1. If at root directory (e.g. after chroot)
	 *    then ignore it so can't get out.
	 * 2. If this vnode is the root of a mounted
	 *    filesystem, then replace it with the
	 *    vnode which was mounted on so we take the
	 *    .. in the other file system.
	 */
	if (ndp->ni_isdotdot) {
		for (;;) {
/* 17 Aug 92*/		if ((dp == ndp->ni_rootdir) || (dp == rootdir)) {
				ndp->ni_dvp = dp;
				ndp->ni_vp = dp;
				VREF(dp);
				goto nextname;
			}
			if ((dp->v_flag & VROOT) == 0 ||
			    (ndp->ni_nameiop & NOCROSSMOUNT))
				break;
			tdp = dp;
			dp = dp->v_mount->mnt_vnodecovered;
			vput(tdp);
			VREF(dp);
			VOP_LOCK(dp);
		}
	}

	/*
	 * We now have a segment name to search for, and a directory to search.
	 */
	if (error = VOP_LOOKUP(dp, ndp, p)) {
#ifdef DIAGNOSTIC
		if (ndp->ni_vp != NULL)
			panic("leaf should be empty");
#endif
#ifdef NAMEI_DIAGNOSTIC
		printf("not found\n");
#endif
		if (flag == LOOKUP || flag == DELETE ||
		    error != ENOENT || *cp != 0)
			goto bad;
		/*
		 * If creating and at end of pathname, then can consider
		 * allowing file to be created.
		 */
		if (ndp->ni_dvp->v_mount->mnt_flag & rdonly) {
			error = EROFS;
			goto bad;
		}
		/*
		 * We return with ni_vp NULL to indicate that the entry
		 * doesn't currently exist, leaving a pointer to the
		 * (possibly locked) directory inode in ndp->ni_dvp.
		 */
		if (ndp->ni_nameiop & SAVESTART) {
			ndp->ni_startdir = ndp->ni_dvp;
			VREF(ndp->ni_startdir);
		}
		return (0);
	}
#ifdef NAMEI_DIAGNOSTIC
	printf("found\n");
#endif

	dp = ndp->ni_vp;
	/*
	 * Check for symbolic link
	 */
	if ((dp->v_type == VLNK) &&
	    ((ndp->ni_nameiop & FOLLOW) || *ndp->ni_next == '/')) {
		ndp->ni_more = 1;
		return (0);
	}

	/*
	 * Check to see if the vnode has been mounted on;
	 * if so find the root of the mounted file system.
	 */
mntloop:
	while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
	       (ndp->ni_nameiop & NOCROSSMOUNT) == 0) {
		while(mp->mnt_flag & MNT_MLOCK) {
			mp->mnt_flag |= MNT_MWAIT;
			tsleep((caddr_t)mp, PVFS, "lookup", 0);
			goto mntloop;
		}
		if (error = VFS_ROOT(dp->v_mountedhere, &tdp))
			goto bad2;
		vput(dp);
		ndp->ni_vp = dp = tdp;
	}

nextname:
	/*
	 * Not a symbolic link.  If more pathname,
	 * continue at next component, else return.
	 */
	if (*ndp->ni_next == '/') {
		ndp->ni_ptr = ndp->ni_next;
		while (*ndp->ni_ptr == '/') {
			ndp->ni_ptr++;
			ndp->ni_pathlen--;
		}
		vrele(ndp->ni_dvp);
		goto dirloop;
	}
	/*
	 * Check for read-only file systems.
	 */
	if (flag == DELETE || flag == RENAME) {
		/*
		 * Disallow directory write attempts on read-only
		 * file systems.
		 */
		if ((dp->v_mount->mnt_flag & rdonly) ||
		    (wantparent && (ndp->ni_dvp->v_mount->mnt_flag & rdonly))) {
			error = EROFS;
			goto bad2;
		}
	}
	if (ndp->ni_nameiop & SAVESTART) {
		ndp->ni_startdir = ndp->ni_dvp;
		VREF(ndp->ni_startdir);
	}
	if (!wantparent)
		vrele(ndp->ni_dvp);
	if ((ndp->ni_nameiop & LOCKLEAF) == 0)
		VOP_UNLOCK(dp);
	return (0);

bad2:
	if ((ndp->ni_nameiop & LOCKPARENT) && *ndp->ni_next == '\0')
		VOP_UNLOCK(ndp->ni_dvp);
	vrele(ndp->ni_dvp);
bad:
	vput(dp);
	ndp->ni_vp = NULL;
	return (error);
}
Commit	Line	Data
c2714ef5	1	/*
	2	* Copyright (c) UNIX System Laboratories, Inc. All or some portions
	3	* of this file are derived from material licensed to the
	4	* University of California by American Telephone and Telegraph Co.
	5	* or UNIX System Laboratories, Inc. and are reproduced herein with
	6	* the permission of UNIX System Laboratories, Inc.
	7	*/
15637ed4 RG	8	/*
	9	* Copyright (c) 1982, 1986, 1989 Regents of the University of California.
	10	* All rights reserved.
	11	*
	12	* Redistribution and use in source and binary forms, with or without
	13	* modification, are permitted provided that the following conditions
	14	* are met:
	15	* 1. Redistributions of source code must retain the above copyright
	16	* notice, this list of conditions and the following disclaimer.
	17	* 2. Redistributions in binary form must reproduce the above copyright
	18	* notice, this list of conditions and the following disclaimer in the
	19	* documentation and/or other materials provided with the distribution.
	20	* 3. All advertising materials mentioning features or use of this software
	21	* must display the following acknowledgement:
	22	* This product includes software developed by the University of
	23	* California, Berkeley and its contributors.
	24	* 4. Neither the name of the University nor the names of its contributors
	25	* may be used to endorse or promote products derived from this software
	26	* without specific prior written permission.
	27	*
	28	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	29	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	30	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	31	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	32	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	33	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	34	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	35	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	36	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	37	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	38	* SUCH DAMAGE.
	39	*
600f7f07	40	* from: @(#)vfs_lookup.c 7.32 (Berkeley) 5/21/91
c2714ef5	41	* $Id: vfs_lookup.c,v 1.5 1993/11/25 01:33:41 wollman Exp $
15637ed4 RG	42	*/
	43
	44	#include "param.h"
4c45483e	45	#include "systm.h"
15637ed4 RG	46	#include "syslimits.h"
	47	#include "time.h"
	48	#include "namei.h"
	49	#include "vnode.h"
	50	#include "mount.h"
	51	#include "errno.h"
	52	#include "malloc.h"
	53	#include "filedesc.h"
	54	#include "proc.h"
	55
	56	#ifdef KTRACE
	57	#include "ktrace.h"
	58	#endif
	59
bbc3f849 GW	60	u_long nextvnodeid;
bbc3f849 GW	61
15637ed4 RG	62	/*
	63	* Convert a pathname into a pointer to a locked inode.
	64	*
	65	* The FOLLOW flag is set when symbolic links are to be followed
	66	* when they occur at the end of the name translation process.
	67	* Symbolic links are always followed for all other pathname
	68	* components other than the last.
	69	*
	70	* The segflg defines whether the name is to be copied from user
	71	* space or kernel space.
	72	*
	73	* Overall outline of namei:
	74	*
	75	* copy in name
	76	* get starting directory
	77	* while (!done && !error) {
	78	* call lookup to search path.
	79	* if symbolic link, massage name in buffer and continue
	80	* }
	81	*/
4c45483e	82	int
15637ed4 RG	83	namei(ndp, p)
	84	register struct nameidata *ndp;
	85	struct proc *p;
	86	{
	87	register struct filedesc fdp; / pointer to file descriptor state */
	88	register char cp; / pointer into pathname argument */
	89	register struct vnode dp; / the directory we are searching */
	90	struct iovec aiov; /* uio for reading symbolic links */
	91	struct uio auio;
	92	int error, linklen;
	93
	94	ndp->ni_cred = p->p_ucred;
	95	fdp = p->p_fd;
	96
	97	/*
	98	* Get a buffer for the name to be translated, and copy the
	99	* name into the buffer.
	100	*/
	101	if ((ndp->ni_nameiop & HASBUF) == 0)
	102	MALLOC(ndp->ni_pnbuf, caddr_t, MAXPATHLEN, M_NAMEI, M_WAITOK);
	103	if (ndp->ni_segflg == UIO_SYSSPACE)
	104	error = copystr(ndp->ni_dirp, ndp->ni_pnbuf,
4c45483e	105	MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
15637ed4 RG	106	else
15637ed4 RG	107	error = copyinstr(ndp->ni_dirp, ndp->ni_pnbuf,
4c45483e	108	MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
15637ed4 RG	109	if (error) {
	110	free(ndp->ni_pnbuf, M_NAMEI);
	111	ndp->ni_vp = NULL;
	112	return (error);
	113	}
	114	ndp->ni_loopcnt = 0;
	115	#ifdef KTRACE
	116	if (KTRPOINT(p, KTR_NAMEI))
	117	ktrnamei(p->p_tracep, ndp->ni_pnbuf);
	118	#endif
	119
	120	/*
	121	* Get starting point for the translation.
	122	*/
	123	if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL)
	124	ndp->ni_rootdir = rootdir;
	125	dp = fdp->fd_cdir;
	126	VREF(dp);
	127	for (;;) {
	128	/*
	129	* Check if root directory should replace current directory.
	130	* Done at start of translation and after symbolic link.
	131	*/
	132	ndp->ni_ptr = ndp->ni_pnbuf;
	133	if (*ndp->ni_ptr == '/') {
	134	vrele(dp);
	135	while (*ndp->ni_ptr == '/') {
	136	ndp->ni_ptr++;
	137	ndp->ni_pathlen--;
	138	}
	139	dp = ndp->ni_rootdir;
	140	VREF(dp);
	141	}
	142	ndp->ni_startdir = dp;
	143	if (error = lookup(ndp, p)) {
	144	FREE(ndp->ni_pnbuf, M_NAMEI);
	145	return (error);
	146	}
	147	/*
	148	* Check for symbolic link
	149	*/
	150	if (ndp->ni_more == 0) {
	151	if ((ndp->ni_nameiop & (SAVENAME \| SAVESTART)) == 0)
	152	FREE(ndp->ni_pnbuf, M_NAMEI);
	153	else
	154	ndp->ni_nameiop \|= HASBUF;
	155	return (0);
	156	}
	157	if ((ndp->ni_nameiop & LOCKPARENT) && ndp->ni_pathlen == 1)
	158	VOP_UNLOCK(ndp->ni_dvp);
	159	if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
	160	error = ELOOP;
	161	break;
	162	}
	163	if (ndp->ni_pathlen > 1)
	164	MALLOC(cp, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
	165	else
	166	cp = ndp->ni_pnbuf;
	167	aiov.iov_base = cp;
	168	aiov.iov_len = MAXPATHLEN;
	169	auio.uio_iov = &aiov;
	170	auio.uio_iovcnt = 1;
	171	auio.uio_offset = 0;
	172	auio.uio_rw = UIO_READ;
173	auio.uio_segflg = UIO_SYSSPACE;
174	auio.uio_procp = (struct proc *)0;
175	auio.uio_resid = MAXPATHLEN;
176	if (error = VOP_READLINK(ndp->ni_vp, &auio, p->p_ucred)) {
177	if (ndp->ni_pathlen > 1)
178	free(cp, M_NAMEI);
179	break;
180	}
181	linklen = MAXPATHLEN - auio.uio_resid;
182	if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
183	if (ndp->ni_pathlen > 1)
184	free(cp, M_NAMEI);
185	error = ENAMETOOLONG;
186	break;
187	}
188	if (ndp->ni_pathlen > 1) {
189	bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
190	FREE(ndp->ni_pnbuf, M_NAMEI);
191	ndp->ni_pnbuf = cp;
192	} else
193	ndp->ni_pnbuf[linklen] = '\0';
194	ndp->ni_pathlen += linklen;
195	vput(ndp->ni_vp);
196	dp = ndp->ni_dvp;
197	}
198	FREE(ndp->ni_pnbuf, M_NAMEI);
199	vrele(ndp->ni_dvp);
200	vput(ndp->ni_vp);
201	ndp->ni_vp = NULL;
202	return (error);
203	}
204
205	/*
206	* Search a pathname.
207	* This is a very central and rather complicated routine.
208	*
209	* The pathname is pointed to by ni_ptr and is of length ni_pathlen.
210	* The starting directory is taken from ni_startdir. The pathname is
211	* descended until done, or a symbolic link is encountered. The variable
212	* ni_more is clear if the path is completed; it is set to one if a
213	* symbolic link needing interpretation is encountered.
214	*
215	* The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
216	* whether the name is to be looked up, created, renamed, or deleted.
217	* When CREATE, RENAME, or DELETE is specified, information usable in
218	* creating, renaming, or deleting a directory entry may be calculated.
219	* If flag has LOCKPARENT or'ed into it, the parent directory is returned
220	* locked. If flag has WANTPARENT or'ed into it, the parent directory is
221	* returned unlocked. Otherwise the parent directory is not returned. If
222	* the target of the pathname exists and LOCKLEAF is or'ed into the flag
223	* the target is returned locked, otherwise it is returned unlocked.
224	* When creating or renaming and LOCKPARENT is specified, the target may not
225	* be ".". When deleting and LOCKPARENT is specified, the target may be ".".
226	* NOTE: (LOOKUP \| LOCKPARENT) currently returns the parent vnode unlocked.
227	*
228	* Overall outline of lookup:
229	*
230	* dirloop:
231	* identify next component of name at ndp->ni_ptr
232	* handle degenerate case where name is null string
233	* if .. and crossing mount points and on mounted filesys, find parent
234	* call VOP_LOOKUP routine for next component name
235	* directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
236	* component vnode returned in ni_vp (if it exists), locked.
237	* if result vnode is mounted on and crossing mount points,
238	* find mounted on vnode
239	* if more components of name, do next level at dirloop
240	* return the answer in ni_vp, locked if LOCKLEAF set
241	* if LOCKPARENT set, return locked parent in ni_dvp
242	* if WANTPARENT set, return unlocked parent in ni_dvp
243	*/
4c45483e	244	int
15637ed4 RG	245	lookup(ndp, p)
	246	register struct nameidata *ndp;
	247	struct proc *p;
	248	{
	249	register char cp; / pointer into pathname argument */
	250	register struct vnode dp = 0; / the directory we are searching */
	251	struct vnode tdp; / saved dp */
	252	struct mount mp; / mount table entry */
	253	int docache; /* == 0 do not cache last component */
	254	int flag; /* LOOKUP, CREATE, RENAME or DELETE */
	255	int wantparent; /* 1 => wantparent or lockparent flag */
	256	int rdonly; /* mounted read-only flag bit(s) */
	257	int error = 0;
	258
	259	/*
	260	* Setup: break out flag bits into variables.
	261	*/
	262	flag = ndp->ni_nameiop & OPMASK;
	263	wantparent = ndp->ni_nameiop & (LOCKPARENT\|WANTPARENT);
	264	docache = (ndp->ni_nameiop & NOCACHE) ^ NOCACHE;
	265	if (flag == DELETE \|\| (wantparent && flag != CREATE))
	266	docache = 0;
	267	rdonly = MNT_RDONLY;
	268	if (ndp->ni_nameiop & REMOTE)
	269	rdonly \|= MNT_EXRDONLY;
	270	ndp->ni_dvp = NULL;
	271	ndp->ni_more = 0;
	272	dp = ndp->ni_startdir;
	273	ndp->ni_startdir = NULLVP;
	274	VOP_LOCK(dp);
	275
	276	dirloop:
	277	/*
	278	* Search a new directory.
	279	*
	280	* The ni_hash value is for use by vfs_cache.
	281	* The last component of the filename is left accessible via
	282	* ndp->ptr for callers that need the name. Callers needing
	283	* the name set the SAVENAME flag. When done, they assume
	284	* responsibility for freeing the pathname buffer.
	285	*/
	286	ndp->ni_hash = 0;
	287	for (cp = ndp->ni_ptr; cp != 0 && cp != '/'; cp++)
	288	ndp->ni_hash += (unsigned char)*cp;
	289	ndp->ni_namelen = cp - ndp->ni_ptr;
	290	if (ndp->ni_namelen >= NAME_MAX) {
	291	error = ENAMETOOLONG;
	292	goto bad;
	293	}
	294	#ifdef NAMEI_DIAGNOSTIC
	295	{ char c = *cp;
	296	*cp = '\0';
	297	printf("{%s}: ", ndp->ni_ptr);
	298	*cp = c; }
	299	#endif
	300	ndp->ni_pathlen -= ndp->ni_namelen;
	301	ndp->ni_next = cp;
	302	ndp->ni_makeentry = 1;
	303	if (*cp == '\0' && docache == 0)
	304	ndp->ni_makeentry = 0;
	305	ndp->ni_isdotdot = (ndp->ni_namelen == 2 &&
	306	ndp->ni_ptr[1] == '.' && ndp->ni_ptr[0] == '.');
	307
	308	/*
309	* Check for degenerate name (e.g. / or "")
310	* which is a way of talking about a directory,
311	* e.g. like "/." or ".".
312	*/
313	if (ndp->ni_ptr[0] == '\0') {
314	if (flag != LOOKUP \|\| wantparent) {
315	error = EISDIR;
316	goto bad;
317	}
318	if (dp->v_type != VDIR) {
319	error = ENOTDIR;
320	goto bad;
321	}
322	if (!(ndp->ni_nameiop & LOCKLEAF))
323	VOP_UNLOCK(dp);
324	ndp->ni_vp = dp;
325	if (ndp->ni_nameiop & SAVESTART)
326	panic("lookup: SAVESTART");
327	return (0);
328	}
329
330	/*
331	* Handle "..": two special cases.
332	* 1. If at root directory (e.g. after chroot)
333	* then ignore it so can't get out.
334	* 2. If this vnode is the root of a mounted
335	* filesystem, then replace it with the
336	* vnode which was mounted on so we take the
337	* .. in the other file system.
338	*/
339	if (ndp->ni_isdotdot) {
340	for (;;) {
341	/* 17 Aug 92*/ if ((dp == ndp->ni_rootdir) \|\| (dp == rootdir)) {
342	ndp->ni_dvp = dp;
343	ndp->ni_vp = dp;
344	VREF(dp);
345	goto nextname;
346	}
347	if ((dp->v_flag & VROOT) == 0 \|\|
348	(ndp->ni_nameiop & NOCROSSMOUNT))
349	break;
350	tdp = dp;
351	dp = dp->v_mount->mnt_vnodecovered;
352	vput(tdp);
353	VREF(dp);
354	VOP_LOCK(dp);
355	}
356	}
357
358	/*
359	* We now have a segment name to search for, and a directory to search.
360	*/
361	if (error = VOP_LOOKUP(dp, ndp, p)) {
362	#ifdef DIAGNOSTIC
363	if (ndp->ni_vp != NULL)
364	panic("leaf should be empty");
365	#endif
366	#ifdef NAMEI_DIAGNOSTIC
367	printf("not found\n");
368	#endif
369	if (flag == LOOKUP \|\| flag == DELETE \|\|
370	error != ENOENT \|\| *cp != 0)
371	goto bad;
372	/*
373	* If creating and at end of pathname, then can consider
374	* allowing file to be created.
375	*/
376	if (ndp->ni_dvp->v_mount->mnt_flag & rdonly) {
377	error = EROFS;
378	goto bad;
379	}
380	/*
381	* We return with ni_vp NULL to indicate that the entry
382	* doesn't currently exist, leaving a pointer to the
383	* (possibly locked) directory inode in ndp->ni_dvp.
384	*/
385	if (ndp->ni_nameiop & SAVESTART) {
386	ndp->ni_startdir = ndp->ni_dvp;
387	VREF(ndp->ni_startdir);
388	}
389	return (0);
390	}
391	#ifdef NAMEI_DIAGNOSTIC
392	printf("found\n");
393	#endif
394
395	dp = ndp->ni_vp;
396	/*
397	* Check for symbolic link
398	*/
399	if ((dp->v_type == VLNK) &&
400	((ndp->ni_nameiop & FOLLOW) \|\| *ndp->ni_next == '/')) {
401	ndp->ni_more = 1;
402	return (0);
403	}
404
405	/*
406	* Check to see if the vnode has been mounted on;
407	* if so find the root of the mounted file system.
408	*/
409	mntloop:
410	while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
411	(ndp->ni_nameiop & NOCROSSMOUNT) == 0) {
412	while(mp->mnt_flag & MNT_MLOCK) {
413	mp->mnt_flag \|= MNT_MWAIT;
73419b27	414	tsleep((caddr_t)mp, PVFS, "lookup", 0);
15637ed4 RG	415	goto mntloop;
	416	}
	417	if (error = VFS_ROOT(dp->v_mountedhere, &tdp))
	418	goto bad2;
	419	vput(dp);
	420	ndp->ni_vp = dp = tdp;
	421	}
	422
	423	nextname:
	424	/*
	425	* Not a symbolic link. If more pathname,
	426	* continue at next component, else return.
	427	*/
	428	if (*ndp->ni_next == '/') {
	429	ndp->ni_ptr = ndp->ni_next;
	430	while (*ndp->ni_ptr == '/') {
	431	ndp->ni_ptr++;
	432	ndp->ni_pathlen--;
	433	}
	434	vrele(ndp->ni_dvp);
	435	goto dirloop;
	436	}
	437	/*
	438	* Check for read-only file systems.
	439	*/
	440	if (flag == DELETE \|\| flag == RENAME) {
	441	/*
	442	* Disallow directory write attempts on read-only
	443	* file systems.
	444	*/
	445	if ((dp->v_mount->mnt_flag & rdonly) \|\|
	446	(wantparent && (ndp->ni_dvp->v_mount->mnt_flag & rdonly))) {
	447	error = EROFS;
	448	goto bad2;
	449	}
	450	}
	451	if (ndp->ni_nameiop & SAVESTART) {
	452	ndp->ni_startdir = ndp->ni_dvp;
	453	VREF(ndp->ni_startdir);
	454	}
	455	if (!wantparent)
	456	vrele(ndp->ni_dvp);
	457	if ((ndp->ni_nameiop & LOCKLEAF) == 0)
	458	VOP_UNLOCK(dp);
	459	return (0);
	460
	461	bad2:
	462	if ((ndp->ni_nameiop & LOCKPARENT) && *ndp->ni_next == '\0')
	463	VOP_UNLOCK(ndp->ni_dvp);
	464	vrele(ndp->ni_dvp);
	465	bad:
	466	vput(dp);
	467	ndp->ni_vp = NULL;
	468	return (error);
	469	}